Associate Professor Mahmud Rahman

This study evaluates the potential exposure to arsenic (As) and other elements in rice from two severely arsenic (As)-impacted districts (Comilla and Chandpur) of Bangladesh. Rice samples were collected from 99 households and analyzed for this purpose. The mean concentrations of As, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn in rice were 187 µg/kg, 40 µg/kg, 16 µg/kg, 819 µg/kg, 1.8 mg/kg, 7.3 mg/kg, 549 µg/kg, 61 µg/kg, and 8.9 mg/kg, respectively. Food and drinking water contribute 20.2, 0.27, 0.24, 6.9, 20, 100, 5.3, 1.6 and 100 µg of As, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn per kg bw daily, respectively. Drinking water contributes 92% of the total dietary intake of As to adults whereas food contributes 90-100% for other elements. The estimated health risk index (HRI) for As, Cd, Cr, Cu, Pb, Mn, Ni, and Zn are 67.4, 0.27, 2.3, 0.54, 0.41, 0.73, 0.27, and 0.33, respectively. The results show that As and Cr in food and drinking water pose significant health risks to the study population as the values of HRIs were greater than 1.

Owing to the similar chemistry of phosphorus (P) and arsenic (As), sodium bicarbonate (0.5 N NaHCO3) is commonly used to extract plant accessible As in soil. This extractant has neither been tested widely in relation to plant As, nor is this extractant compatible with inductively coupled plasma mass spectrometry (ICP-MS) due to the high concentration of dissolved solid. Subsequently, it is of utmost important to design a suitable chemical extraction method in order to estimate plant available As compatibility with ICP-MS. For this purpose, paired soil and plant samples were collected from paddy fields located in Nadia, West Bengal, India. Soil was extracted with 0.5 M NaHCO3, 0.1 N and 0.5 N phosphoric acid (H3PO4), 0.1 N and 0.5 N sulfuric acid (H2SO4), 0.1 N, 0.5 N, 1.0 N, 1.5 N HNO3 and 0.01 M calcium chloride (CaCl2) solution. Arsenic extracted with NaHCO3, H3PO4 and H2SO4 was determined in hydride generation-atomic absorption spectrophotometer (HG-AAS), while ICP-MS served to determine As extracted from soil with HNO3. Olsen-extractable As in soils ranged from 0.48 to 3.57 mg kg-1 with a mean value of 1.45 mg kg-1. The extractable As content in soil varied from 0.01 to 10.1 mg kg-1 across the extractants. In the case of grain As, 0.1 N H3PO4, 0.5 N NaHCO3 and 1.5 N HNO3 extractable As had distinctly higher correlation coefficients (r = 0.49**, r = 0.47**, r = 0.45**) when compared to other extractants. More or less similar relationships of extractable As were obtained with straw As content like that of rice grain. In view of rapidity of the soil test method for As, 1.5 N HNO3 can be recommended for assessing available As in soil.

Water-soluble dyes are a common problem in wastewater treatment, requiring highly efficient methods for removal. In this study, novel sustainable adsorbents made from graphene-oxide (GO) and other materials, such as eggshell-derived calcium oxide nanoparticles (CaONPs-ES), fish bone calcium oxide nanoparticles (CaONPs-FB), and durian shell activated carbon (DSAC) were synthesized, characterized, and demonstrated for soluble dye removal from wastewater. Fermented maize grain extract (MES) was used as a green cross-linker in the synthesis process. The resulting nanocomposites, GO@CaONPs-ES/DSAC and GO@CaONPs-FB/DSAC, showed promising adsorption capabilities for methylene blue (MB) dye removal from aqueous environments. The prepared nanocomposites (GO@CaONPs-ES/DSAC and GO@CaONPs-FB/DSAC) were characterize using state-of-art instrumental techniques. The BET measurement revealed that the nanocomposites surface areas were enhanced due to the cross-linking phenomenon, improving their adsorption capability towards MB dye treatment. The adsorption data of GO@CaONPs-FB/DSAC and GO@CaONPs-ES/DSAC was well fitted to the Harkins-Jura and Freundlich models, respectively. The maximum sorption capacities of GO@CaONPs-ES/DSAC and GO@CaONPs-FB/DSAC were 1274.5 and 689.7 mg/g, respectively. The MB dye removal mechanism was driven by p-p interaction, hydrogen bonding, electrostatic attraction and physical interactions and the adsorption process of the nanocomposites followed pseudo-second-order kinetics. The adsorptive performance of the nanocomposites was stable, showing ~96.45 % and ~85.18 % after 10 successive cycles for GO@CaONPs-ES/DSAC and GO@CaONPs-FB/DSAC respectively. Cost evaluation revealed that bulk synthesis of GO@CaONPs-ES/DSAC and GO@CaONPs-FB/DSAC nanocomposites is cost-effective for treating large quantities of MB contaminated water and other potential dyes as well. Finally, the independent and synergetic contributions between pH, adsorbent dosage and temperature on MB removal by GO@CaONPs-ES/DSAC and GO@CaONPs-FB/DSAC were studied and optimized by central composite design (CCD) an aspect of the response surface methodology (RSM). Finally, this study suggests that the novel green cross-linking approach has a significant impact in enhancing the adsorptive performances of the developed nanocomposites to effectively capture MB from aqueous environment.

To mobilize inorganic soil phosphorus (P), soils from humid tropical agro-ecosystems were treated with P solubilizing microbes (PSMs) and graded doses of rice straw (RS) under varying hydrothermal scenarios (temperature and soil moisture suctions), likely, S1 (25 °C and 0.033 MPa), S2 (35 °C and 0.033 MPa), S3 (25 °C and 0.1 MPa), and S4 (35 °C and 0.1 MPa). Six treatments were obtained, T0 (no PSMs and no RS), T1 (RS at 3570 mg kg-1 or 8 Mg RS ha-1 + PSMs), T2 (RS at 4465 mg kg-1 or 10 Mg RS ha-1 + PSMs), T3 (RS at 5355 mg kg-1 or 12 Mg RS ha-1 + PSMs), T4 (RS at 6250 mg kg-1 or 14 Mg RS ha-1 + PSMs), and T5 (RS at 0 mg kg-1 + PSMs). Temperature sensitivity of organic P mineralization was the highest for T5, whereas, inorganic P solubilization was the highest for T4 at 0.033 MPa and for T5 at 0.1 MPa. Inorganic P solubilization rate under S1, S2 and S4 were ~167%, 288% and 54% greater than S3, respectively. Under S2, T4 could solubilize ~11, 21 and 9.2 ppm of NH4F-P, NaOH-P and H2SO4-P, respectively. At 0.033 MPa suctions, T3 significantly reduced hysteresis by ~10% at 25 0C and 12% at 35 0C, respectively, over control. Path analysis indicated silicon concentrations and changes in soil pH were the most significant factors to influence soil environment to mobilize soil P. Reduction in hysteresis effect was mostly achieved by altering microbial factors. T3 could solubilize ~2.96% and 3.26% of inorganic P under S1 and S2 enhancing P availability by 3.35, and 4 times over control, respectively. Overall, annual RS (12 Mg ha-1)+PSMs application under varying moisture availability could sustain P availability in humid tropical Inceptisols of India.

A secure aquatic environment is essential for both aquatic and terrestrial life. However, rising populations and the industrial revolution have had a significant impact on the quality of the water environment. Despite the implementation of strong and adapted environmental policies for water treatment worldwide, the issue of organic dyes in wastewater remains challenging. Thus, this study aimed to develop an efficient, cost-effective, and sustainable material to treat methylene blue (MB) in an aqueous environment. In this research, maize extract solution (MES) was utilized as a green cross-linker to induce precipitation, conjugation, and enhance the adsorption performance of graphene oxide (GO) cross-linked with durian shell activated carbon (DSAC), resulting in the formation of a GO@DSAC composite. The composite was investigated for its adsorptive performance toward MB in aqueous media. The physicochemical characterization demonstrated that the cross-linking method significantly influenced the porous structure and surface chemistry of GO@DSAC. BET analysis revealed that the GO@DSAC exhibited dominant mesopores with a surface area of 803.67 m2/g. EDX and XPS measurements confirmed the successful cross-linking of GO with DSAC. The adsorption experiments were well described by the Harkin-Jura model and they followed pseudo-second order kinetics. The maximum adsorption capacity reached 666.67 mg/g at 318 K. Thermodynamic evaluation indicated a spontaneous, feasible, and endothermic in nature. Regenerability and reusability investigations demonstrated that the GO@DSAC composite could be reused for up to 10 desorption-adsorption cycles with a removal efficiency of 81.78%. The selective adsorptive performance of GO@DSAC was examined in a binary system containing Rhodamine B (RhB) and methylene orange (MO). The results showed a separation efficiency (a) of 98.89% for MB/MO and 93.66% for MB/RhB mixtures, underscoring outstanding separation capabilities of the GO@DSAC composite. Overall, the GO@DSAC composite displayed promising potential for the effective removal of cationic dyes from wastewater.

Evaluating the toxicity of Palm Oil Mill Effluent (POME) is critical as part of the effort to develop waste management regulations for the palm oil industry. In this study, we investigated the acute toxicity of POME on growth performance, behavioral response, and histopathology of gill and liver tissues of zebrafish (Danio rerio). In total, 550 adult male zebrafish were used for the toxicity experiment including range finding test, acute toxicity test, growth performance and behaviour test. Static non-renewal acute toxicity bioassays were conducted by exposing fish to POME (1.584¿9.968 mL/L) for 96 h. Growth performance, behavior response, and histopathological lesions in untreated and POME treated (96-h LC50: 5.156 mL/L) fish were measured at 24, 48, 72 and 96 h. Time-dependent significant decline in body length and body weight of POME-exposed zebrafish was observed. Furthermore, several behavioral changes were recorded, including hyperactivity, loss of balance, excessive mucus secretion, and depigmentation. Decreasing operculum movement and oxygen consumption rate as well as alterations in gill tissues (i.e. hyperplasia, hypertrophy, hemorrhage, and necrosis) of POME-exposed zebrafish were observed, suggesting a dysfunction in respiratory performance. On the other hand, liver tissue alterations (congestion, hemorrhage, hyperplasia, shrinkage of hepatocytes, hydrophilic degeneration, and necrosis) indicated a disruption in detoxification performance. We conclude that exposure to POME at acute concentration caused histopathological lesions both in gill and liver tissue along with changes in fish behaviors which disrupted respiratory and detoxification performance, resulting in mortality and reduced growth of zebrafish. These findings might provide valuable information for guiding POME management and regulation.

Rice is a major dietary source of essential trace elements required for the human body but also can be an exposure pathway to different potentially toxic trace elements. This study determined various essential and toxic trace elements in rice from Bangladeshi markets and their possible health risks. Concentrations of essential and toxic trace elements in rice varied significantly from location to location. Mean concentrations (mg kg-1 as dry weight) of essential trace elements were found in the following order - Zn>Mn>Cu>Fe>Mo>Se>Co - and were within their maximum allowable limits. The average concentrations (mg kg-1) of toxic trace elements were as follows: As: 0.17, Cr: 0.18, Ni: 0.55 and Pb: 0.18, while 7% and 40% of the rice samples surpassed, respectively, the EU recommended limits of As and Pb. This study revealed that rice could be a primary exposure pathway of toxic elements, leading to either noncarcinogenic or carcinogenic health problems for daily rice consumers. The non-carcinogenic health risk was mainly associated with As which contributed 77% to the hazard index. The carcinogenic risk measured as incremental lifetime cancer risk (ILCR) was high (>10-4) with As, Cr and Ni, while Pb showed a moderate (<10-4) carcinogenic risk to adults. Rice can substantially be contaminated by trace elements other than As with potential human health risks. Consequently, regular monitoring of the marketed rice grain is demanded, backed up by viable mitigation strategies for reducing toxic elements uptake by rice grains.

In this study, zinc terephthalate-metal-organic framework decorated on the surface of poultry manure-derived biochar (ZT-MOF@Ag@C) was successfully fabricated and employed as nano-adsorbent material for Congo Red (CR)-treated aqueous solution. The physical characteristics of the developed ZT-MOF@Ag@C adsorbent were analyzed by the Brunauer¿Emmett¿Teller (BET) theory, Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) Scanning Electron Microscopy equipped with Energy-Dispersive X-Ray Spectroscopy (SEM/EDS), and X-Ray Photoelectron Spectrometer (XPS). The characterization analysis revealed that biochar modification with ZT-MOF and AgNPs greatly enhanced the surface area. The mesopores ZT-MOF@Ag@C BET surface area of 1028 m2/g showed a maximum adsorption capacity of 416.6 mg/g. The Langmuir isotherm and pseudo-second order kinetic models best described the adsorption process of CR onto ZT-MOF@Ag@C. The thermodynamic studies revealed that the adsorption of CR on the ZT-MOF@Ag@C was spontaneous and exothermic. The as-fabricated ZT-MOF@Ag@C was observed to be stable after sixth adsorption-desorption cycles. ZT-MOF@Ag@C composite exhibited excellent potential for the treatment of CR dye from the aqueous solution. The point of zero charge, BET, XRD, XPS, SEM, and FTIR analyses confirmed that the adsorption of CR onto ZT-MOF@Ag@C nanocomposite is majorly dominated by the following mechanisms: p-p interaction, pore adsorption, electrostatic interaction, and hydrogen bonding. The biochar-derived adsorbent's performance was significantly improved through modification, thereby suggesting an effective strategy for boosting the sorbent activity.

Halophytes residing in metal-contaminated saltmarsh habitats may employ strategies to enhance fitness of the next generation. We aimed to test the hypothesis that Juncus acutus individuals inhabiting metal-contaminated locations would experience elevated tolerance of offspring to metals compared to plants residing in locations with no metal contamination history. J. acutus seeds (F1 generation) were collected from F0 parent plants residing at eight locations of a contemporary sediment metal gradient (contaminated to uncontaminated) across the coast of NSW, Australia (Hunter river, Lake Macquarie and Georges River). Seeds were exposed in the laboratory to incremental Zn (0.0¿1.6 mM) and Pb (0.0¿0.50 mM) for nine (9) days, and % germination, germination rate, root elongation and vigour index were assessed for the determination of tolerance. Greater root accumulation (BCF = 1.01) of Zn and subsequent translocation to aerial parts (culm BCF = 0.58 and capsule BCF = 0.85) were exhibited in parents plants, whereas Pb was excluded from roots (BCF = 0.60) and very little translocation to aerial portions of the plant was observed (culm BCF = 0.02 and capsule BCF = 0.05). F1 offspring exhibited tolerance to Zn with EC50 (% germination) significantly correlated with their parents' culm (R2 = 0.93, p = 0.00) and capsule (R2 = 0.57; p = 0.03) Zn. No correlations were observed between offspring Pb tolerance and Pb in parents¿ plant tissues. Enhanced tolerance to the essential metal Zn may be because Zn is very mobile in the parent plant and seeds experience greater Zn load as a significant portion of sediment Zn reaches capsules (85%). Thus, Zn tolerance in J. acutus seeds is likely attributable to acclimation via maternal transfer of Zn; however, further manipulative experiments are required to disentangle potential acclimation, adaptation or epigenetic effects in explaining the tolerance observed.

Rice arsenic (As) contamination and its consumption poses a significant health threat to humans. The present study focuses on the contribution of arsenic, micronutrients, and associated benefit-risk assessment through cooked rice from rural (exposed and control) and urban (apparently control) populations. The mean decreased percentages of As from uncooked to cooked rice for exposed (Gaighata), apparently control (Kolkata), and control (Pingla) areas are 73.8, 78.5, and 61.3%, respectively. The margin of exposure through cooked rice (MoEcooked rice) < 1 signifies the existence of health risk for all the studied exposed and control age groups. The respective contributions of iAs (inorganic arsenic) in uncooked and cooked rice are nearly 96.6, 94.7, and 100% and 92.2, 90.2, and 94.2% from exposed, apparently control, and control areas. LCR analysis for the exposed, apparently control, and control populations (adult male: 2.1 × 10¿3, 2.8 × 10¿4, 4.7 × 10¿4; adult female: 1.9 × 10¿3, 2.1 × 10¿4, 4.4 × 10¿4; and children: 5.8 × 10¿4, 4.9 × 10¿5, 1.1 × 10¿4) through cooked rice is higher than the recommended value, i.e., 1 × 10¿6, respectively, whereas HQ > 1 has been observed for all age groups from the exposed area and adult male group from the control area. Adults and children from rural area showed that ingestion rate (IR) and concentration are the respective influencing factors towards cooked rice As, whereas IR is solely responsible for all age groups from urban area. A vital suggestion is to reduce the IR of cooked rice for control population to avoid the As-induced health risks. The average intake (µg/day) of micronutrients is in the order of Zn > Se for all the studied populations and Se intake is lower for the exposed population (53.9) compared to the apparently control (140) and control (208) populations. Benefit-risk assessment supported that the Se-rich values in cooked rice are effective in avoiding the toxic effect and potential risk from the associated metal (As). Graphical Abstract: [Figure not available: see fulltext.]

Phycoremediation has emerged as a proven economical technique for removing heavy metals, including lead (Pb). However, the phycoremediation capacity of Pb by Spirulina platensis under different environmental condition (including salinity) has not yet been investigated. Hence, this study aims to examine the phycoremediation capacity of Pb by S. platensis at different levels of salinity. S. platensis was exposed to Pb (4 mg/L) at different levels of salinity (up to 30 ppt) for 12 days. The results indicated that salinity fluctuation was able to reduce phycoremediation capacity of Pb. The highest removal efficiency of Pb was observed in optimum salinity and decreased significantly both in lower and higher salinity treatments. Physiological disturbances in S. platensis were indicated by changes in functional groups and morphology. The morphology of Spirulina platensis both in lower and higher salinity treatments appeared to have changed its shape, resembling a disjointed thread with fading color.

Water pollution due to elevated arsenic (As) levels is a very serious health issue worldwide. Employing adsorbent substances to remove As from an aqueous environment presents a viable solution to this pressing concern. The As adsorption behavior onto modified clay (kaolinite, bentonite) and red mud in aqueous media was investigated in this study. Specific surface area (SSA), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies confirmed successful modification of kaolinite, bentonite, and red mud through Fe-impregnate and dimethyl sulfoxide (DMSO)-intercalation. The incorporation of iron and DMSO improved the ability to remove As. The kinetic study showed that the adsorption equilibrium for both clay minerals and red mud products was reached within approximately 120 min, and the data fitted well to the simple Elovich, power function, and pseudo-second-order equation. Of all the products, Fe-Bentonite exhibited the highest As adsorption capacity, with a value of 581.2 µg g-1 (initial As concentration = 50 µg mL-1). Revealed in this study is that Fe-Bentonite, DMSO-Bentonite, and Fe-Red mud were the best-screened products for removing As from the aqueous system.

Rice-derived food products could be a major dietary source of both essential and non-essential elements to people; hence it is crucial to assess their concentrations to ensure the safe consumption of these products. In this study, six different types of rice-based products collected from Australian markets were analysed for essential and non-essential elements to evaluate the exposure and health risk. The estimated intake (EI) of essential elements from baby rice substantially contributed to the recommended dietary allowance of Fe (27%) and Mn (43%) for infants compared to different rice-based products for children and adults. The EI values of Cd, Cr, Ni and Pb were 0.15 ¿ 1.17, 5.68 ¿ 16.24, 7.47 ¿ 16.24 and 0.40 ¿ 1.21 µg, respectively, from an average recommended serving of different rice-based products. Compared to the tolerable daily intake (TDI) and tolerable weekly intake (TWI) provided by the European Food Safety Authority (EFSA), both average daily intake (ADI) and average weekly intake (AWI) values of the respective non-essential elements were much lower. Thus, this study results indicated that the rice-based products pose no potential health risk to consumers although regular monitoring is necessary to reduce health risks especially for infants and children.

Untreated biomedical wastes discharged into water bodies, primarily by hospitals and health care facilities; release a wide range of contaminants that poses danger to human health and environmental sustainability. Therefore, developing sustainable and dependable treatment methods for biomedical waste is a top priority. Nano-sized graphene is known to have excellent unique properties including high current density, optical, mechanical, thermal conductivity, high chemical stability, high surface area and chemical stability. Graphene-based nanomaterials and derivatives as a result of their excellent properties have received increased attention in wastewater treatment in recent years. Despite significant progress in the production of graphene at laboratory scale, there is a need to focus on green large-scale graphene synthesis to pave the way for adopting graphene-based technology on an industrial scale. In wastewater treatment, advanced development of pure graphene on various significant functionalization exhibits excellent adsorption efficiency when functionalized when compared to other alternatives. Top-down as well as bottom-up approaches such as chemical vapour deposition, and chemical exfoliation among other approaches can be used for graphene synthesis and functionalization. As a result, the benefits of graphene oxide-based nanomaterials have been unraveled in the treatment of biomedical wastewater. Adsorption and photocatalysis techniques have sparked widespread interest because they allow for the environmentally friendly treatment of biomedical wastewater, and significant progress has been made in recent years. This study examined the graphene synthesis method and the use of graphene oxide-based nanomaterials as adsorbents and photocatalysts in the treatment of biomedical waste. Furthermore, the recyclability, thermal stability, and future perspectives on the directions and difficulties in graphene-based material synthesis are summarized.

A greenhouse pot experiment was conducted with seven different levels of sludge (0, 5, 10, 20, 40, 80, 160 g kg-1) to assess the potential impact of sludge application on soybean¿(Glycine max (L.) Merr.) productivity, metal accumulation and translocation, and physico-chemical changes in acid and alkaline soils. The outcomes revealed that the application of sludge @ 5.0 to 160 g kg-1 resulted in a significant (p < 0.05) increase in seed and straw yield in both acid and alkaline soils compared to control. All the assessed heavy metals in soybean were within permissible ranges and did not exceed the phytotoxic limit, except for Fe, Zn, and Cu in the roots from the application of sewage sludge. The values of bioaccumulation factor (BFroot/soil) and translocation factor i.e., TFstraw/root and TFseed/straw were < 1.0 for Ni, Pb and Cr. Overall, for all the sludge application doses the soil pH was observed to increase in the acid soil and decline in alkaline soil when compared to the control. All the investigated heavy metals (Fe, Mn, Zn, Cu, Ni, Cd, Pb, and Cr) in the different plant tissues (root, straw and seed) of soybean were correlated with the soil variables. The study finds that sludge can be a potential organic fertilizer and function as an eco-friendly technique for the recycling of nutrients in the soil while keeping a check on the heavy metals¿ availability to plants.

In this review article, a comprehensive meta-analysis based on available literature information has been undertaken to make a relative comparison of total arsenic in rice grain. This involves analyzing the findings of various peer-reviewed studies that examined arsenic-contaminated Asian regions. Also, this article highlights the regional-level human health risks caused by the consumption of arsenic-contaminated rice in the three regions of Asia. Deriving such information at the continental level is of major importance in view of the need for proper monitoring and alleviating serious and continually emerging human health issues in arsenic-contaminated areas. One aim of this paper is to highlight the potential of a viable modeling approach for appraising the danger posed by arsenic in soil-plant-human system. There is an urgent need to fix the safe limit of bioavailable arsenic in soil because total arsenic in soil is not a good index of the arsenic hazard. Our hypothesis is finding out whether the modeling approach can be used in establishing a safe limit of bioavailable arsenic in soils with reference to human health. To achieve the above-mentioned objectives, we have selected reported rice grain arsenic content data from Asian countries following the PRISMA guidelines. Carcinogenic and non-carcinogenic risk was calculated following the US EPA¿s guidelines. It emerged that adults in Asian countries are prone to a high risk of cancer due to their consumption of arsenic-contaminated rice. South Asia (SA), South East Asia (SEA), and East Asia (EA) exceeded the US EPA-prescribed safe limit for cancer risk with ~ 100 times higher probability of cancer due to rice consumption. The hazard quotient for the ingestion of arsenic containing rice was 4.526 ± 5.118 for SA, 2.599 ± 0.801 for SEA, and 2.954 ± 2.088 for EA. These figures are all above the permissible limit of HQ of 1. The solubility free ion activity model can predict arsenic transfer from soil to rice grain based on easily measurable soil properties and be used to fix the safe limit of bioavailable arsenic in paddy soils. The methods and findings of this review are expected to be useful for regional-level policymaking and mobilizing resources to alleviate public health issues caused by arsenic.

Groundwater quality assessment is crucial for determining the suitability of water resources required for human consumption and agriculture. To investigate the quality of groundwater in Tundla block, Uttar Pradesh, India, 50 samples were harvested from boreholes and hydrochemistry analysis was carried out. Entropy water quality index (EWQI) and irrigation water quality index (IWQI) were computed employing different suitability parameters to assess its suitability for drinking and irrigation purposes. Geochemical modelling using PHREEQC served to simulate the solubility equilibria of mineral combinations by determining the saturation index (SI). Based on EWQI values the groundwater samples fall under two classes, these being medium (70%) and poor (30%) quality. The USSL plot indicated high salinization of the groundwater sample. Piper plot reveals the presence of two hydrogeochemical facies, viz. mixed type (72% samples) and Cl--Na+ type (28% samples). Geochemical modelling based on thermodynamic laws confirms the presence of high-solubility evaporitic minerals such as anhydrite, fluorite, and gypsum, and more stable precipitated mineral types like calcite, aragonite, and dolomite. A fraction of samples showed over-saturation of some minerals, namely dolomite (38%), calcite (32%), and aragonite (20%). Around 28% of the samples exhibited a large amount of F- in groundwater at concentrations higher than BIS-prescribed safe limits (>1.5 mg L-1). Conducting health risk assessment shows that children and infants in the region are at a non-cancer risk (HQ > 1) due to sustained F- intake through drinking water. The spatial distribution of EWQI revealed medium-quality groundwater for drinking purposes in the south-central sub-area of Tundla. With reference to irrigation, groundwater sources are of better quality in the south sub-area.

Trace elements (TEs) contamination of agricultural soils requires suitable criteria for regulating their toxicity limits in soil and food crops, which depends on their potential ecological risk spanning regional to global scales. However, no comprehensive study is available that links TE concentrations in paddy soil with ecological and human health risks in less developed regions like Pakistan. Here we evaluated the data set to establish standard guidelines for defining the hazard levels of various potentially toxic TEs (such as As, Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb, Se, Zn) in agricultural paddy soils of Punjab, Pakistan. In total, 100 topsoils (at 0¿15 cm depth) and 204 rice plant (shoot and grain) samples were collected from five ecological zones of Punjab (Gujranwala, Hafizabad, Vehari, Mailsi, and Burewala), representing the major rice growing regions in Pakistan. The degree of contamination (Cd) and potential ecological risk index (PERI) established from ecological risk models were substantially higher in 100% and 97% of samples, respectively. The positive matrix factorization (PMF) model revealed that the elevated TEs concentration, notably Cd, As, Cr, Ni, and Pb, in the agricultural paddy soil was attributed to the anthropogenic activities and groundwater irrigation. Moreover, the concentration of these TEs in rice grains was higher than the FAO/WHO's safe limits. This study provided a baseline, albeit critical knowledge, on the impact of TE-allied ecological and human health risks in the paddy soil-rice system in Pakistan; and it opens new avenues for setting TEs guidelines in agro-ecological zones globally, especially in underdeveloped regions.

In this study, we first report a systematic checklist of commercial marine fish species from Weh Island, Indonesia, including notes on their distribution pattern, conservation status, and commercial value. Fish sampling was conducted at three major fish markets in Weh Island, and these specifically were Cangkoan Fish Market, Kuta Timu Fish Market, and Balohan Fish Market. A total of 50 fish species belonging to 8 orders and 24 families were documented. Carangidae (12%, 6 species) was the predominant family, followed by the Scaridae (10%, 5 species) and other families (78%, 22 families, 39 species). Based on the IUCN red list, commercial marine fi sh species in Weh Island were dominated by the "Least Concern" category (78%, 39 species), followed by the "Not Evaluated" (14%, 7 species), the "Near Threatened" (4%, 2 species), and the "Data Deficient" (4%, 2 species). The market price of the fish ranged from 0.34 USD/kg to 6.19 USD/kg, with three fish families included in the high commercial value, namely the Clupeidae, Carcharhinidae, and Serranidae.

Dietary selenium (Se) deficiency is a well-known global problem originating from food crops grown in Se-deficient soil. Agronomic Se biofortification is one of the suitable options to minimize Se deficiency. Sulfur (S) is chemically similar to Se, and the role of S on the uptake and transformation of Se in grain has not been resolved. Considering this, our study examines the influence of S on the speciation and accumulation of Se in two chickpea cultivars (Amber and PBA sheamer) grown in Se-deficient soil under glasshouse conditions. Two doses of S (0 and 14 mg kg-1) as sulfate and three doses of Se (0, 1, and 2 mg kg-1) as selenate (SeVI) were used in a randomized factorial design. The addition of SeVI increased the Se content in grain in both cultivars compared to the control treatment. Speciation of Se analysis in grain showed that most (85%) of the Se accumulated in chickpea grain in the organic forms of Se as SeCys and MeSeCys. At 2 mg/kg Se addition, the biomass and grain yield was significantly reduced (P < 0.01), while S addition tended to increase the yield. Inorganic Se was below 15%, primarily as SeVI. PBA Sheamer, a desi type and widely grown chickpea cultivar, showed the most significant proportion of organic Se species, SeCys (57%) and SeMeCys (40%). Application of S contemporarily with Se showed increased SeMeCys production in the grain of PBA Sheamer cultivar. These findings indicated that the accumulation and speciation of Se in chickpea grain was dependent on both Se and S fertilization.

Chromium (Cr) pollution is a significant environmental concern with remediation challenge. Hexavalent chromium (Cr(VI)) is more toxic than trivalent chromium (Cr(III)) due to its mutagenicity and oncogenicity. In this investigation, a multi-functional material, copper nanoclusters (CuNCs)-halloysite nanotubes (HNT) composite (CuNCs@HNT), has been synthesised in an eco-friendly manner and utilised for Cr(VI) remediation. Advanced analytical tools confirmed the seeding of ultra-fine CuNCs onto HNT surfaces. The maximum adsorption capacity of CuNCs@HNT is 79.14 ± 6.99 mg/g at pH 5 ± 0.1 with an increment at lower pHs. This performance was comparable for real surface stream water as well as other reported materials. The pseudo-second-order kinetic-, intra-particle diffusion- and Freundlich isotherm models well fit the experimental data implying that the chemisorption, multiphase diffusion and multi-molecular layer distribution occurred during adsorption. The Fourier-transform infrared and the x-ray photoelectron spectra also ensured the transformation of Cr(VI) to Cr(III) indicating the material's suitability for concurrent adsorption and reduction of Cr(VI). While coexisting cations and anions did not overwhelm this adsorption, CuNCs@HNT was regenerated and reused five successive times in adsorption-desorption cycles without significant loss of adsorption capacity and material's integrity. Therefore, this multi-functional, biocompatible, low-cost and stable CuNCs@HNT composite may have practical application for similar toxic metals remediation.

Cadmium (Cd) is a widespread environmental contaminant, and its increasing concentrations in rice poses significant risks to human health. Globally, rice is a staple food for millions of people, and consequently, effective strategies to reduce Cd accumulation in rice are needed. This study investigates the effect of soil pH (Soil 1: 4.6; Soil 2: 6.6) and iron (Fe) application (at 0, 1.0 and 2.0 g/kg) on Fe plaque formation, Cd sequestration in Fe plaques and Cd bioaccumulation in different parts of the rice plant for three different Cd-graded paddy soils (0, 1.0 and 3.0 mg/kg, respectively) using two Australian rice cultivars under glasshouse conditions. Results show that grain and straw yield declined as Cd toxicity increased, and the toxic effects of Cd were lower in the Quest cultivar than in the Langi cultivar. With applications of Cd at 1.0 mg/kg and 3.0 mg/kg, Cd concentrations in rice grown in Soil 1 were 1.09 mg/kg and 1.37 mg/kg, respectively, while those in rice grown in Soil 2 were 0.38 mg/kg and 0.52 mg/kg, respectively. Soil pH significantly affected the bioaccumulation of Cd in different parts of the rice plant. At both levels of Cd application, Cd concentration was highest in the root, followed by the stem, leaf, husk and grain. Cd was more concentrated in Fe plaques formed by the application of Fe than in rice plant tissues. The Quest cultivar had a higher ability to produce Fe plaques and a 1.3- and 1.4-times higher Cd concentration compared with the Langi cultivar in Soils 1 and 2, respectively.

To date, several harmful effects of Palm Oil Mill Effluent (POME) have been reported on aquatic organisms, including fish. However, the turbidity effects of POME on the feeding ability of fish are still unexplored. We first assessed the turbidity effects of POME on the feeding ability of male siamese fighting fish (Betta splendens). Siamese fighting fish were exposed to < 1 NTU (control) and five concentrations of POME turbidity levels, namely 20 NTU (Treatment A), 40 NTU (Treatment B), 60 NTU (Treatment C), 80 NTU (Treatment D), and 100 NTU (Treatment E). Each of the control and treatment groups was maintained in five replicates. Preference tests were carried out in a 10-L aquarium (35 ×21×25 cm3). The feeding rate, time to capture first prey, aggressive behaviour, foraging area, and retinal light adaptation rate and retina histopathology were analyzed. The exposure time for the determination of feeding rate, foraging area, and retinal light adaptation rate and retina histopathology was set for 15 min, while for aggressive behaviour test, the exposure duration was 5 min. Results showed that the feeding rate, aggressive behaviour and foraging area significantly decreased with increasing turbidity levels of POME. In contrast, the time to capture first prey significantly increased. No significant changes in retinal light adaptation rate was recorded between treatments. Furthermore, results showed several retinal degenerations, including reduced granular spherical cells (GL) and detachment of bipolar cells from photoreceptor cells (DBPC) in siamese fighting fish exposed to high-level turbidity of POME. This study provides valuable information to support POME remediation management, especially turbidity parameters.

Lead (Pb) pollution in the environment predominantly occurs through anthropogenic activities, which pose significant threats to human health and that of biota. In this study, Pb and other elements were investigated in different soils (n = 52), crops (n = 24) and water (n = 13) around a lead-acid battery (LAB) recycling workshop in southwestern Bangladesh. Most of the elements¿ concentrations (except Se and Ag) in soil were lower than the background concentrations. However, excessive concentrations of Pb were found in both surface (966 ± 2414 mg kg-1 at 0¿15 cm) and subsurface (230 ± 490 mg kg-1 at 15¿30 cm) soil. Although no definitive pattern or direction in elemental concentration in soil was observed, relatively higher concentrations of most elements were detected at the southeast part of the factory. The LAB factory, brick kiln, agricultural and geogenic activities might be the sources of these elements in soil. Extremely high amounts of Cr, As, Cd, and Pb were found in the food crops around the area. In particular, the Pb concentrations were 114 ± 155 and 665 ± 588 mg kg -1 dry weight in rice grain and straw, respectively, which reflected the emissions of Pb from the LAB recycling workshop. Moreover, 40% and 100% of the groundwater samples exceeded, respectively, the WHO provisional guideline values for As (0.01 mg L-1) and Pb (0.05 mg L-1). Consequently, a high level of Pb contamination in the soil was observed while assessing different soil pollution indices. Human health risk assessment indicated severe carcinogenic (from Pb, As, and Cr intake) and non-carcinogenic (from Pb, As, Co, Cr, Ni and Sb intake) health risks are associated with rice and groundwater consumption. It is concluded that all LAB recycling workshops should be better managed to prevent Pb pollution from seeping into the environment.

Groundwater contaminated by arsenic (As) is a serious concern because it poses a significant threat to millions of people reliant on both drinking and irrigation of farms. Hence, the low-cost and efficient treatment of these waters is of utmost importance. This study presents the ecofriendly synthesis of magnetite nanoparticles (Fe3O4 NPs)-immobilized halloysite nanotube (HNT) composite (Fe3O4@HNT) for remediating arsenate [As(V)] from water. High-resolution transmission electron microscopy confirmed that ultrasmall Fe3O4 NPs (4.52 ± 1.63 nm) were immobilized on the interior surface of HNT. Fe3O4@HNT possesses a larger surface area (82 ± 0.23 m2/g) and a higher thermal stability (7.1% weight loss at 950 °C) than a pristine HNT (47.23 ± 0.14 m2/g and 12.6%, respectively). Adsorption kinetics were best fitted with pseudo-second-order and intraparticle diffusion, while the isotherms results were best supported with the Freundlich model (R2 = 0.99 in each case). Therefore, it could be surmised that multiphase rate-controlling chemisorption occurred during adsorption. The thermodynamics data revealed the endothermic nature of As(V) adsorption by Fe3O4@HNT. Fourier transform infrared and X-ray photelectron spectroscopy analyses confirmed chemical bonding between As and Fe. In addition, Fe3O4@HNT was easily separable by an external magnet (the saturation magnetization value was 20 emu/g), which is an additional benefit of the material to be used on an industrial scale. The material was also reusable after regeneration for five rounds of consecutive sorption-desorption with excellent efficiency and no substantial loss of structural integrity. Furthermore, Fe3O4@HNT removed more than 99% As(V) from the groundwater, signifying its viability in real-case implementation. Cost-benefit analysis ensured that Fe3O4@HNT was cost-effective, while its biocompatibility test confirmed no detrimental impact on soil bacterial growth once the spent material had been disposed. Consequently, cheap, easily separable, reusable, and biocompatible Fe3O4@HNT may be a prospective composite for the sustainable eradication of As and other metallic toxicants from wastewater.

Farmers use wastewater for irrigation in many developing countries, for example Bangladesh, India, China, Sri Lanka and Vietnam because they have limited access to clean water. This study explored cadmium (Cd) bioaccumulation in two spring wheat cultivars (cv. Mustang and Lancer), which were grown in different concentrations of Cd (0,1, 2, 4, and 8¿mg kg-1) in agricultural soils. The half maximum inhibitory concentration (IC50) values were 4.21 ± 0.29 and 4.02 ± 0.95, respectively, whereas the maximum health risk index (HRI) was 3.85 ± 0.049 and 5.33 ± 0.271, respectively, for Mustang and Lancer. In other words, the malondialdehyde content increased significantly in Mustang (around five-fold) and Lancer (around four-fold) compared with the control treatment. Results revealed that Cd content was well above the acceptable limit (HRI >1) in the two cultivars when exposed to different levels of Cd stress. The tolerant cultivar (Mustang) has potential to chelate Cd in the nonedible parts of plants in variable fractions and can be used efficiently to improve growth and macro- and micro-nutrients content while reducing Cd concentration in plants in Cd-contaminated soil. It can also diminish the HRI, which may help to protect humans from Cd risks. The two cultivars¿ nutrient availability and sorption capacity significantly shape their survival and adaptability under Cd stress. Based on what is documented in the current study, we can conclude that Mustang is more tolerant and poses fewer health hazards to people than Lancer because of its capacity to maintain grain macro- and micro-nutrients under Cd stress.

Having up-to-date knowledge on the mineralization of organic materials and release of nutrients is of paramount significance to ensure crops¿ nutrient demands, increase nutrient use efficiency and ensure the right fertilizer application at the right time. This study seeks to evaluate the mineralization patterns of various manures viz. cowdung (CD), cowdung slurry (CDSL), tricho-compost (TC), vermicompost (VC), poultry manure (PM), poultry manure slurry (PMSL), and mungbean residues (MR). The objective being to establish their efficiency in releasing nutrients under aerobic (field capacity) and anaerobic (waterlogging) conditions. The incubation experiment was designed using a Completely Randomized Design (CRD) that took into account three variables: Manures, soil moisture, and incubation period. The mineralization of carbon (C) and nitrogen (N) ranged from 11.2 to 100.1% higher under aerobic conditions rather than anaerobic ones. The first-order kinetic model was used to mineralize both elements. C mineralization was 45.8 to 498.1% higher in an amount from MR under both moisture conditions. For N release, MR and PM exerted maximum amounts in anaerobic and aerobic scenarios, respectively. However, the rate of C and N mineralization was faster in TC compared to other manures in both moisture conditions. Although TC was 1.4 to 37.7% more efficient in terms of rapidity of mineralization, MR and PM performed better concerning the quantity of nutrient release and soil fertility improvement. PM had 22¿24% higher N mineralization potential than PMSL while CDSL had 46¿56% higher N mineralization potential than CD. C and N mineralization in soil was greater under aerobic conditions compared to what occurred in the anaerobic context. Depending on mineralization potential, the proper type and amount of manure should be added to soil to increase crops¿ nutrient use efficiency, which in turn should lead to better crop production.

This study investigated the impact of soil type and rice cultivars on variations in the iron plaque formation and cadmium (Cd) accumulation by different portions of rice seedlings under the influence of Fe amendment. The experiments were performed in pots under glasshouse conditions using two typical paddy soils. Rice seedlings were exposed to three concentrations of Cd (0, 1 and 3 mg kg-1 soil) and Fe (0, 1.0 and 2.0 g kg-1 soil). The results revealed that shoot biomass decreased by 12.2¿23.2% in Quest and 12.8¿30.8% in Langi in the Cd1.0 and Cd3.0 treatments, while shoot biomass increased by 11.2¿19.5% in Quest and 26¿43.3% in Langi in Fe1.0 and Fe2.0 as compared to the Fe control. The Cd concentration in the roots and shoots of rice seedlings were in the order of Langi cultivar > Quest cultivar, but the Fe concentration in rice tissues showed the reverse order. Fe plaque formations were promoted by Fe application, which was 7.8 and 10.4 times higher at 1 and 2 g kg-1 Fe applications compared to the control Fe treatment. The Quest cultivar exhibited 13% higher iron plaque formation capacity compared to the Langi cultivar in both soil types. These results indicate that enhanced iron plaque formation on the root surface was crucial to reduce the Cd concentration in rice plants, which could be an effective strategy to regulate grain Cd accumulation in rice plants.

Arsenic (As) is one of the major pollutants of groundwater in many developing countries including Bangladesh, and it poses a significant health risk to humans. This study aims to assess the potential health threat to school children through As-contaminated drinking water. For this analysis, 180 samples of water from tubewells located in high school premises in southwestern Bangladesh were analyzed for As and other elements such as iron (Fe), manganese (Mn), calcium (Ca), and magnesium (Mg). Also examined were the physicochemical parameters including, pH, electrical conductivity (EC), total dissolved solids (TDS), turbidity, chloride, and hardness. The results revealed that groundwater is slightly alkaline and very hard. The mean As concentration in drinking water was 71.06 ± 66.47 µg L-1 (range: 1¿250 µg L-1), which was 7-fold higher than the World Health Organization (WHO) provisional guideline value (10 µg L-1). Human health risk assessment was evaluated using hazard quotient (HQ) for As, Fe and Mn, and the cancer risk (CR) assessment for As only. The values of As for HQ and CR (HQ and CR were up to 9.04 and 4.1 × 10-3 for boys and 9.82 and 4.4 × 10-3 for girls, respectively), revealed that children are susceptible to higher risks. The risk was slightly higher in girls than boys were. No health risk was observed in the children when they consumed drinking water containing Mn and Fe. The school-going children are at the greatest threat from As-containing drinking water on school premises, and this situation requires urgent attention to ensure safe potable water in As-endemic areas. Graphical abstract: [Figure not available: see fulltext.].

Supported metal nanoclusters (NCs) are an ideal catalytic system from their ultra-small size (<3 nm), reactivity and confinement on support materials. Whether synthesis of such composite is feasible using copper (Cu) as catalyst on nontoxic and inexpensive support material but without using any toxic reducing agent is yet to be explored. Here, synthesis of CuNCs using only biocompatible glutathione and localised them on halloysite nanotubes (HNTs) would be a sustainable catalyst composite. Following hydrothermal reaction, composites CuNCs@HNT and CuNCs@HNT-PS were synthesised by one-step and post-synthesis methods, respectively. State-of-the-art tools, including high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy revealed NCs formation, chemical states, and confinement and stability as composite, while catalysis reaction was monitored by spectrophotometer. Both composites exhibited faster catalytic performance than did bare NCs for the degradation of contrasting model azo dyes, methylene blue (MB) and methyl orange (MO). CuNCs, CuNCs@HNT and CuNCs@HNT-PS required only 93 ± 1.0, 17.5 ± 2.5 and 27 ± 2.5 s, respectively for 100% degradation of MB whereas >90% degradation of MO occurred by 120 ± 5.21, 75 ± 3.15 and 90 ± 3.61 min, respectively. Composites showed excellent catalytic reusability and environmental nontoxicity. Therefore, as effective and safe catalysts, they can shed light on exploring further usage in the environment and industrial set-ups.

Rice consumption is a major dietary source of Cd and poses a potential threat to human health. The aims of this study were to examine the influence of Fe and Cd application on yield and yield components, dynamics of Cd in pore water, translocation factors, daily dietary intake, and estimation of human health risks. A pot experiment was performed under glasshouse conditions where rice cultivars (Langi and Quest) were cultivated in two dissimilar soils under different levels of Cd (0, 1.0, and 3.0¿mg¿kg-1) and Fe (0, 1.0, and 2.0¿g¿kg-1). The results showed that variation in two rice cultivars in terms of yield and yield-related components was dose dependent. Cadmium concentration in soil pore water was decreased over time and increased with increasing Cd levels but decreased with Fe application. Translocation factors (TFs) from root to straw (TFroot-straw) or straw to husk (TFstraw-husk) were higher than root to grain (TFroot-grain) or straw to grain (TFstraw-grain). The Quest cultivar had 20% lower Cd than the Langi cultivar. Application of Fe at the rate of 1 and 2¿g¿kg-1 soil reduced Cd by 23 and 46%, respectively. Average daily intake (ADI) of Cd exceeded the permissible limit (5.8 × 10-3¿mg -1¿kg-1¿bw per week) when rice plant subjected 1 and 3¿mg¿kg-1 Cd stress with or without Fe application. Results also indicated that ADI value was lower in the Quest cultivar as compared to the Langi cultivar. Estimation of human health risk revealed that the non-carcinogenic risks (HQ > 1) and carcinogenic risks (CR > 1.0 × 10-4) increased with increasing Cd levels in the soil. The application of Fe decreased the human health risks from rice consumption which is more pronounced in Fe 2.0 than in Fe1.0 treatments. The rice cultivar grown in soil-1 (pH 4.6) showed the highest health risks as compared to soil-2 (pH 6.6) and the Quest cultivar had lower health risks than the Langi cultivar.

The current study represents the first attempt to analyse quantitatively, within a phylogenetic framework, uptake and partitioning patterns of copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb) in extant saltmarsh taxa globally, and to assess associations of these patterns with various plant traits indicative of their halophytic adaptations. Despite saltmarsh being diverse taxonomically, most saltmarsh taxa accumulate metals to roots at, or above, unity (> 1). Further, there is significant translocation from roots to shoot for Cu, Zn and Cd (= 1), however, Pb is less mobile (TF = 0.65). Patterns of accumulation were similar among families, except greater Cd accumulation to roots in members of Juncaceae. Patterns of uptake to roots and translocation to leaves were broadly similar among plant type, plant form, habitat and photosynthetic mode. Zinc is lower in the leaves of salt-secreting species for some closely related taxa, suggesting some species co-excrete sodium (Na+) and Zn2+ through glands in leaf tissue. Salinity tolerance has no relationship to metal uptake and translocation. Translocation of Zn is greater at lower Zn sediment exposures, reflecting its active uptake and essentiality, but such bias does not affect outcomes of analyses when included as a covariate.

Estrogenic compounds enter waterways via effluents from wastewater treatment works (WWTW), thereby indicating a potential risk to organisms inhabiting adjacent receiving waters. However, little is known about the loads or concentrations of estrogenic compounds that enter Australian WWTWs, the efficiency of removing estrogenic compounds throughout the various stages of tertiary WWTW processes (which are common in Australia), nor the concentrations released into estuarine or marine receiving waters, and the associated risk for aquatic taxa residing in these environments. Therefore, seven estrogenic compounds, comprising the natural estrogens estrone (E1), 17ß-estradiol (E2) and estriol (E3), the synthetic estrogen (EE2), and the industrial chemicals bisphenol A (BPA), 4-t-octyl phenol (4-t-OP) and 4-nonyl phenol (4-NP), in wastewater samples were quantified via liquid chromatographic-mass spectrometry (LC-MS) after solid-phase extraction at different stages of wastewater treatment and associated receiving waters. The concentrations of the target compounds in wastewater ranged from < LOQ (limit of quantification) to 158 ng/L for Tanilba Bay WWTW and < LOQ to 162 ng/L for Belmont WWTW. Most target compounds significantly declined after the secondary treatment phase. Appreciable removal efficiency throughout the treatment process was observed with removal from 39.21 to 99.98% of influent values at both WWTWs. The reduction of the natural estrogens (E1, E2 and E3) and 4-t-OP were significantly greater than EE2, BPA, and 4-NP in both WWTWs. Risk quotients (RQs) were calculated to assess potential ecological risks from individual estrogenic compounds. In predicted diluted effluents, no targeted compounds showed any ecological risk (RQ =1.65 × 10-2) at both WWTWs. Similarly, all RQs for shore samples at both WWTWs were below 1. Finally, the hazard index (HI), which represents combined estrogenic contaminants¿ ecological risk, indicated no mentionable risk for predicted diluted effluents (HI = 0.0097 to 0.0218) as well as shoreline samples (HI = 0.393 to 0.522) in the receiving estuarine or marine waters.

Open field burning of crop residue causes severe air pollution and greenhouse gas emission contributing to global warming. In order to seek an alternative, the current study was initiated to explore the prospective of lignocellulolytic microbes to expedite in situ decomposition of crop residues. Field trials on farmers¿ field were conducted in the state of Haryana and Maharashtra, to target the burning of rice and wheat residue and sugarcane trash, respectively. A comparative study among crop residue removal (CRR), crop residue burning (CRB) and in situ decomposition of crop residues (IND) revealed that IND of rice and wheat residues took 30¿days whereas IND of sugarcane trash took 45¿days. The decomposition status was assessed by determining the initial and final lignin to cellulose ratio which increased significantly from 0.23 to 0.25, 0.21 to 0.23 and 0.24 to 0.27 for rice, wheat residues and sugarcane trash, respectively. No yield loss was noticed in IND for both rice-wheat system and sugarcane-based system; rather IND showed relatively better crop yield as well as soil health parameters than CRB and CRR. Furthermore, the environmental impact assessment of residue burning indicated a substantial loss of nutrients (28¿31, 23¿25 and 51¿77¿kg¿ha-1 of N+P2O5+K2O for rice, wheat and sugarcane residue) as well as the emission of pollutants to the atmosphere. However, more field trials, as well as refinement of the technology, are warranted to validate and establish the positive potential of in situ decomposition of crop residue to make it a successful solution against the crop residue burning.

This study examined the impact of iron (Fe) plaque deposition and varietal variation on cadmium (Cd) accumulation in the rice plants (Oryza sativa L.) in a hydroponic experiment under controlled conditions. Fe was applied at the rate of 0, 50 and 100 mg L-1 to the nutrient solution to generate varying amounts of Fe plaque deposition around the root of the rice seedlings. The seedlings were then treated with Cd at the rate of 0, 0.5 and 1.0 mg L-1 in the nutrient solution. Reddish-brown colored Fe plaque is induced gradually on the roots of rice seedlings after Fe supplementation in the nutrient solution. Results showed that the biomass production differed markedly among the rice varieties due to the application of Fe with or without Cd stress. The Quest variety demonstrated the highest capacity of Fe plaque formation compared to the other varieties. The application of Fe and Cd significantly affected the Cd concentration in the citrate-bicarbonate-dithionite (CBD) extracts of roots and in the rice seedlings. The exogenous application of Cd significantly increased the root Cd content, which was greater than the shoot Cd content. The Fe plaque deposition capacity markedly varied among the examined varieties. The Cd concentrations in shoots declined by adding Fe. This study results demonstrated that boosted Fe plaque formation can minimize detrimental effects of Cd on rice shoot growth to some extent, but the root tissues are the main barrier to Cd accumulation and movements in the interior of the rice plants.

Prolonged exposure to inorganic arsenic (As) via drinking water is a major concern as it poses significant human health risks. Removal of As is crucial but requires effective and environment-friendly clean-up technology to avoid any additional risk to the environment. In this study, we developed Australian smectite (smec)-supported nano zero-valent iron (nZVI) composite for arsenate i.e., As(V) sorption. We used a range of tools, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and energy dispersion X-ray (EDS) spectroscopy to characterise the material. SEM and TEM images and elemental mapping of the composite reflect that the smectite layer was surrounded by a chain of iron nanobeads evenly distributed on clay particles, which is quite exceptional among currently available nZVIs. The maximum As(V) sorption capacity of this composite was 23.12 mg/g in the ambient conditions. Using X-ray photoelectron spectroscopy we unveiled chemical states of As and Fe before and after the sorption process. Additionally, the release of iron nanoparticles from the composite at various pHs (3-10) were found negligible, which demonstrates the effectiveness of smec-nZVI to remove As(V) from contaminated water without posing any secondary pollutant.

Anthropogenic metal pollution remains a substantial threat to remnant saltmarsh ecosystems as they continue to decline globally. Metal pollutants impart sublethal stress on saltmarsh halophytes evident at transcriptomic, proteomic, metabolomic and physiological levels. Halophytes form the basal underpinning of saltmarsh ecosystems and as such changes to their physiology may have subsequent detrimental effects on higher levels of ecological organisation. This concept forms the basis of a mechanistic framework for toxicity: an adverse outcome pathway (AOP). AOPs facilitate the use of molecular and biological markers to predict consequent effects on population parameters, and community structure and function. We reviewed the current literature on common anthropogenically enhanced metals (Cu, Zn, Cd and Pb) in saltmarsh ecosystems internationally. The literature amassed to date indicates a lack of data in regard to the impacts of metals at higher levels of biological organisation and insufficient relevant data available to develop reliable AOPs. Collectively, metals impart sublethal stress at the transcriptomic, proteomic, and metabolomic levels and targets of toxic effect are predominantly biomolecules involved in metal transport and detoxification, antioxidant pathways associated with metal-induced oxidative stress, and photosynthetic biochemistry. Thus, these targets would be useful biomarkers in future studies designed to develop AOPs in saltmarsh taxa.

Arum plant parts such as stem, leaf and corm and the corresponding farm soils were sampled from four As-impacted districts of Bangladesh to assess the potential health risk to humans from toxic elements (TEs) including arsenic (As), cadmium (Cd) and lead (Pb). The mean concentrations of As in arum leaf, stem and corm were 150 µg/kg, 107 µg/kg and 101 µg/kg, respectively, whereas mean Cd in arum leaf, stem and corm were 115 µg/kg, 261 µg/kg and 180 µg/kg, respectively and mean Pb in arum leaf, stem and corm were 595 µg/kg, 403 µg/kg and 577 µg/kg, respectively. Daily dietary intake of As, Cd and Pb from sampled arum were 0.003, 0.008 and 0.021 µg/kg bw for adults. As per capita intake of arum is low, hazard quotient (HQ) values for all TEs were found minimal, which reveals no appreciable health risk associated with arum consumption to the local inhabitants.

We examined the patterns of uptake and partitioning of metal(loid)s in Suaeda australis from three highly urbanised estuaries (Sydney Olympic Park, Hunter Wetlands and Lake Macquarie) in NSW, Australia. Of these, Sydney Olympic Park was found to be the most contaminated estuary in terms of combined sediment metal(loid) load, followed by Hunter Wetlands and lowest in Lake Macquarie (via PERMANOVA). Uptake in roots was greater for the essential metals Cu and Zn along with the non-essential metal Cd and the metalloid Se (root BCFs >1) and lower for Pb and As (root BCFs <1). Substantial barriers for translocation from roots to stems were identified for all metal(loid)s (stem TFs; 0.07¿0.68). Conversely, unrestricted flow from stems to leaves was observed for all metal(loid)s at unity or higher (leaf TFs = 1). Strong linear relationships between sediment and root for Zn and Pb were observed, indicating roots as a useful bioindicator.

This study investigates the occurrence, distribution, and potential ecological risk of trace elements (TEs) along with the hydrogeochemical characteristics of coastal surface water collected from the southern Caspian coasts in the Mazandaran province of Iran. Eighteen coastal water sites were sampled and analyzed using inductively coupled plasma¿mass spectrometry and ion chromatography to determine concentrations of TEs and major ions, respectively. Mean concentrations (µg/l) of TEs in the water followed the order: Al (154.3) > Fe (73.6) > Zn (67.8) > Mn (29.9) > Cu (5.7) > Mo (3.7) > Cd (2.8) > Se (2.3) > V (1.9) > Co = As (1.8) > Sb (1.2) > Pb (0.6). TEs displayed high variations within samples, reflecting many sources that control their concentrations in the coastal water. Most TEs displayed elevated concentrations in the east and west of the study area. The Na-Cl water type in the majority of investigated sites indicates excess alkaline elements and strong acid anions relative to alkaline earth cations and weak acid anions. Considering the saturation states of minerals, carbonate and evaporite minerals are oversaturated and unsaturated in surface water, respectively. Compositional interrelations between aqueous species showed that reverse cation exchange may have occurred. The excess SO42- content, derived from irrigation return flow and domestic greywater, probably plays a crucial role in the mobilization and transport of Zn and Pb by binding to sulfate ligands and forming aqueous complexes. Ecological risk assessment of TEs revealed that water in the majority of sites is safe in terms of As, Se, Pb, and Cd content, and unsuitable with respect to Zn and Cu. Acute and chronic toxicities of Cu and Zn are reported in several sites, thus coastal water cannot be used for fishery and protecting ¿nature reserve¿ purposes. However, industrial activity and tourism are safe to be conducted in most coastal water sites.

Food is the major cadmium (Cd)-exposure pathway from agricultural soils to humans and other living entities and must be reduced in an effective way. A plant can select beneficial microbes, like plant-growth-promoting rhizobacteria (PGPR), depending upon the nature of root exudates in the rhizosphere, for its own benefits, such as plant growth promotion as well as protection from metal toxicity. This review intends to seek out information on the rhizo-immobilization of Cd in polluted soils using the PGPR along with plant nutrient fertilizers. This review suggests that the rhizo-immobilization of Cd by a combination of PGPR and nanohybrid-based plant nutrient fertilizers would be a potential and sustainable technology for phytoavailable Cd immobilization in the rhizosphere and plant cellular detoxification, by keeping the plant nutrition flow and green dynamics of plant nutrition and boosting the plant growth and development under Cd stress.

Arsenic (As) bioaccumulation in rice grains has been identified as a major problem in Bangladesh and many other parts of the world. Suitable rice genotypes along with proper water management practice regulating As levels in rice plants must be chosen and implemented. A field study was conducted to investigate the effect of continuous flooding (CF) and alternate wetting and drying (AWD) irrigation on the bioaccumulation of As in ten rice cultivars at three locations having different levels of soil As and irrigation water As. Results showed that As concentration in different parts of rice plants varied significantly (P¿<¿0.0001) with rice genotypes and irrigation practices in the three study locations. Lower levels of As in rice were found in AWD irrigation practice compared to CF irrigation practice. Higher grain As bioaccumulation was detected in plants in areas of high soil As in combination with CF irrigation practice. Our data show that use of AWD irrigation practice with suitable genotypes led to 17 to 35% reduction in grain As level, as well as 7 to 38% increase in grain yield. Overall, this study advances our understanding that, for moderate to high levels of As contamination, the Binadhan-5, Binadhan-6, Binadhan-8, Binadhan-10 and BRRI dhan47 varieties were quite promising to mitigate As induced human health risk.

Total and inorganic arsenic (As) content in rice and rice-based diets (n = 59) obtained from supermarkets in South Australia were studied to investigate the contamination levels and whether consumption of these products pose potential health risks to young children and adults. Results show that of the 59 rice-based products, 31 (53%) exceeded the EU recommended value (100 µg/kg) of As for young children and 13 (22%) samples had higher than maximum level of 200 µg/kg recommended for adults. Arsenic content varies as rice crackers > baby rice > rice cakes > puffed rice > other rice-based snacks > ready-to-eat rice. Of the 6 categories of rice-based products, except ready-to-eat rice, all others exceeded the EU recommended value for young children. Even manufacture recommended servings deliver significant amounts (0.56¿6.87 µg) of inorganic As. These amounts are within the range of BMDL01 values indicated by the European Food Safety Authority (EFSA), which means the risk cannot be avoided for young children and adults considering the levels of total and inorganic As in rice-based products.

An extensive number (965) of rice samples collected by household survey from 73 upazilas (i.e. sub-districts) in Bangladesh was analyzed to determine regional variation, distribution and associated health risks from arsenic (As). No previous study had conducted a study examining such a large number of rice samples. The mean and median concentrations of total As were 126¿µg/kg and 107¿µg/kg, respectively, ranging from between 3 and 680¿µg/kg. Importantly, total As levels of aromatic rice were significantly lower (average 58¿µg/kg) than non-aromatic rice (average 150¿µg/kg) and also varied with rice grain size. The variation in As content was dominated by the location (47% among the upazilas, 71% among districts) and rice variety (14%). Inorganic As content in rice grain ranged between 11 and 502¿µg/kg (n¿=¿162) with the highest fraction being 98.6%. The daily intake of inorganic As from rice ranged between 0.38 and 1.92¿µg/kg BW in different districts. The incremental lifetime cancer risk (ILCR) for individuals due to the consumption of rice varied between 0.57¿×¿10-¿3 to 2.88¿×¿10-¿3 in different districts, and 0.54¿×¿10-¿3 to 2.12¿×¿10-¿3 in different varieties, higher than the US EPA threshold. The 2¿10 age group experiences higher carcinogenic risks than others and females are more susceptible than males.

This study assesses the concentrations of arsenic (As) in water, muscle tissue of four demersal fish species (Chrysichthys nigrodigitatus, Mugil cephalus, Liza falcipinnis and Bathygobious soporator) and whole tissues of periwinkle (Tympanotonus fuscatus) in Lagos Lagoon, Nigeria. The observed mean total As concentration in water (1.29µgl-1) during the wet and dry seasons did not exceed the World Health Organization (WHO) guideline value of 10µgl-1. Among the examined biota, Tympanotonus fuscatus recorded higher As levels (2.31±0.24mgkg-1) and Chrysichthys nigrodigitatus recorded the least As content (0.67±0.08mgkg-1). A significant positive correlation (p<0.05) was observed between As concentrations in fish muscles and water during the dry and wet seasons. The health risks associated with human consumption of fish estimated using Target Hazard Quotient (THQ) were lower than the USEPA guideline value of 1 for all fish species examined except in populations that consume larger amounts of fish. However, higher THQ values (>2) were obtained for Tympanotonus fuscatus, suggesting the potential for non-carcinogenic health outcomes in adults after a prolonged period of consumption. This calls for continuous monitoring and enforcement of regulations to ensure safety of fishery resources from Lagos Lagoon.

The presence of toxic heavy metals and metalloids in aquatic environments constitutes a major risk and there is an urgent need for continuous monitoring of such pollutants. This study assesses the concentrations of arsenic (As) in surface sediments from 15 locations on the Lagos Lagoon, Nigeria during the wet and dry seasons to determine the degree of contamination. The results showed that the mean total As concentration in sediment (2.44 mg kg-1 dry weight) did not exceed the Canadian Interim Sediment Quality Guideline (CISQG) value of 7.24 mg kg-1 dry weight during the wet and dry seasons. Based on the Sediment Quality Guidelines (SQGs) of the United States Environmental Protection Agency (USEPA) and ecological risk assessment using the enrichment factor (EF), contamination factor (CF) and geo-accumulation index (Igeo), the study's results indicate two things: firstly, low to moderate and significant levels of enrichment from As; and secondly, low to moderate degree of contamination in Lagos Lagoon during the study period.

We investigated the extent and severity of groundwater arsenic (As) contamination in five blocks in Patna district, Bihar, India along with As in biological samples and its health effects such as dermatological, neurological and obstetric outcome in some villages. We collected 1365 hand tube-well water samples and analyzed for As by the flow injection hydride generation atomic absorption spectrometer (FI-HG-AAS). We found 61% and 44% of the tube-wells had As above 10 and 50 µg/l, respectively, with maximum concentration of 1466 µg/l. Our medical team examined 712 villagers and registered 69 (9.7%) with arsenical skin lesions. Arsenical skin lesions were also observed in 9 children of 312 screened. We analyzed 176 biological samples (hair, nail and urine). Out of these, 69 people had arsenical skin lesions and rest without skin lesions. We found 100% of the biological samples had As above the normal levels (concentrations of As in hair, nail and urine of unexposed individuals usually ranges from 20 to 200 µg/kg, 20-500 µg/kg and <100 µg/l, respectively), indicating many people are sub-clinically affected. Arsenical neuropathy was observed in 40.5% of 37 arsenicosis patients with 73.3% prevalence for predominant sensory neuropathy and 26.7% for sensor-motor. Among patients, different clinical and electrophysiological neurological features and abnormal quantitative sensory perception thresholds were also noted. The study also found that As exposed women with severe skin lesions had adversely affected their pregnancies. People including children in the affected areas are in danger. To combat As situation in affected areas, villagers urgently need (a) provision of As-safe water for drinking and cooking, (b) awareness about the danger of As toxicity, and (c) nutritious food.

This study investigates the level of contamination and health risk assessment for arsenic (As) and other elements in drinking water, vegetables and other food components in two blocks (Mohiuddinagar and Mohanpur) from the Samastipur district, Bihar, India. Groundwater (80%) samples exceeded the World Health Organization (WHO) guideline value (10. µg/L) of As while Mn exceeded the previous WHO limit of 400. µg/L in 28% samples. The estimated daily intake of As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn from drinking water and food components were 169, 19, 26, 882, 4645, 14582, 474, 1449 and 12,955. µg, respectively (estimated exposure 3.70, 0.41, 0.57, 19.61, 103.22, 324.05, 10.53, 32.21 and 287.90. µg per kg bw, respectively). Twelve of 15 cooked rice contained high As concentration compared to uncooked rice. Water contributes (67%) considerable As to daily exposure followed by rice and vegetables. Whereas food is the major contributor of other elements to the dietary exposure. Correlation and principal component analysis (PCA) indicated natural source for As but for other elements, presence of diffused anthropogenic activities were responsible. The chronic daily intake (CDI) and health risk index (HRI) were also estimated from the generated data. The HRI were >. 1 for As in drinking water, vegetables and rice, for Mn in drinking water, vegetables, rice and wheat, for Pb in rice and wheat indicated the potential health risk to the local population. An assessment of As and other elements of other food components should be conducted to understand the actual health hazards caused by ingestion of food in people residing in the middle Gangetic plain.

Lead (Pb) poisoning in children is a major public health catastrophe worldwide. This report summarises both exposure pathways and blood Pb levels in children below 7. years of age and adults (above 18. years) from the Adudu community living near a lead-zinc mine in Nasawara, Nigeria. The average and median blood Pb levels in children and adults were 2.1 and 1.3 µg/dL, 3.1 and 1.8 µg/dL, respectively. However, Pb in 14% of adults' blood exceeded 5. µg/dL, which is the recommended threshold blood Pb concentration in adults as established by the Centers for Disease Control and Prevention (CDC). Furthermore 68% of adults' blood exceeded blood Pb action level of 2 µg/dL. For children, 11.4% and 31% of the blood samples exceeded 5 µg/dL and 2 µg/dL, respectively, while no safe blood Pb level in children has been recommended. In Nasawara, a significant difference (p< 0.05) was observed between the various age groups in children with 2-4 years old having the highest levels and 6. year old children having the lowest Pb levels. Although this study did not detect elevated levels of Pb in children's blood in regions such as Zamfara, Nigeria and Kabwe, Zambia, a high percentage of samples exceeded 2 µg/dL. Soils, floor dusts, water and crops also reveal that Pb contamination in the study area could potentially be the major cause of blood Pb in the community exposed to mining. This study also observed a significant correlation between water Pb levels of adults and blood Pb levels, suggesting that water is the major exposure pathway. This analysis highlights the need to properly manage mining activities so that the health of communities living in the vicinity of a Pb-Zn mine is not compromised.

This study investigated the uptake of lead (Pb) ions by Na-rich bentonite (Na-bentonite) and Al-pillared bentonite (Al-bentonite) in the presence or absence of organic acids containing different functional groups. Na-bentonite was an effective adsorbent for Pb2+ ions. The element was taken up by the mineral through ion exchange mechanism; and the formation of a lead carbonate hydroxide (hydrocerussite) also occurred. Al-bentonite adsorbed a smaller amount of Pb than Na-bentonite. XRD data indicated that the totality of clay interlayers was occupied by the pillaring agent that led to decrease in Pb uptake. The amount of Pb taken up by Na-bentonite decreased with increasing concentration of citric acid both when Pb and organic acid were added together as a mixture, and when citric acid was added 2 h before the metal ions. Possible reasons for this were the formation of Pb-citrate complexes which had less affinity to Na-bentonite, and also hydrocerussite dissolution at acidic pH. Citric acid, however, did not change Pb uptake by Al-bentonite. Addition of lysine together with Pb did not have any effect on Pb uptake by Na-bentonite and Al-bentonite, which indicated occupation of different adsorption sites by Pb and lysine compared to citrate. However, lysine addition at 1:1 ratio 2 h before Pb decreased the metal uptake, which again may be explained by the effect of lysine in hydrocerussite dissolution. Uptake of Pb in the presence of lysine was also higher when using Na-bentonite compared to Al-bentonite.

Concentrations of inorganic forms [arsenite, As(III) and arsenate, As(V) of arsenic (As) present in groundwater, agricultural soils and subsurface sediments located in the middle Gangetic plain of Bihar, India were determined. Approximately 73% of the groundwater samples (n¿=¿19) show As(III) as the dominant species while 27% reveals As(V) was the dominant species. The concentration of As(III) in agricultural soil samples varies from not detectable to 40¿µg/kg and As(V) was observed as the major species (ranging from 1050 to 6835¿µg/kg) while the total As concentration varied from 3528 to 14,690¿µg/kg. Total extracted concentration of As was higher in the subsurface sediments (range 9119¿20,056¿µg/kg in Methrapur and 4788¿19,681¿µg/kg in Harail Chapar) than the agricultural soil, indicating the subsurface sediment as a source of As. Results of X-ray diffraction (XRD) and environmental scanning electron microscope (ESEM) revealed the presence of hematite and goethite throughout the vertical section below while magnetite was observed only in the upper oxidized layer at Methrapur and Harail Chapar. Alteration of Fe-oxides and presence of fibrous goethite indicating presence of diagenetic sediment. Siderite plays a crucial role as sinks to the As in subsurface sediments. The study also concluded that decomposition of organic matter present in dark and grey sections promote the redox conditions and trigger mobilization of As into groundwater.

Rice is an essential staple food and feeds over half of the world's population. Consumption of rice has increased from limited intake in Western countries some 50¿years ago to major dietary intake now. Rice consumption represents a major route for inorganic arsenic (As) exposure in many countries, especially for people with a large proportion of rice in their daily diet as much as 60%. Rice plants are more efficient in assimilating As into its grains than other cereal crops and the accumulation may also adversely affect the quality of rice and their nutrition. Rice is generally grown as a lowland crop in flooded soils under reducing conditions. Under these conditions the bioavailability of As is greatly enhanced leading to excessive As bioaccumulation compared to that under oxidizing upland conditions. Inorganic As species are carcinogenic to humans and even at low levels in the diet pose a considerable risk to humans. There is a substantial genetic variation among the rice genotypes in grain-As accumulation as well as speciation. Identifying the extent of genetic variation in grain-As concentration and speciation of As compounds are crucial to determining the rice varieties which accumulate low inorganic As. Varietal selection, irrigation water management, use of fertilizer and soil amendments, cooking practices etc. play a vital role in reducing As exposure from rice grains. In the meantime assessing the bioavailability of As from rice is crucial to understanding human health exposure and reducing the risk.

The objective of this study was to determine the magnitude of groundwater arsenic contamination in Shahpur block of Bhojpur district, Bihar state, India and its health effects such as dermal, neurological, obstetric effects, and cancer risk. The School of Environmental Studies (SOES) collected 4704 tube-well water samples from all 88 villages of Shahpur, which were analyzed for arsenic. We found 40.3 and 21.1¿% of the tube-wells had arsenic above 10 and 50¿µg/l, respectively, with maximum concentration of 1805¿µg/l. The study shows that 75,000, 39,000, and 10,000 people could be exposed to arsenic-contaminated water greater than 10, 50, and 300¿µg/l, respectively. Our medical team examined 1422 villagers from Shahpur and registered 161 (prevalence rate, 11.3¿%) with arsenical skin lesions. Arsenical skin lesions were also observed in 29 children of 525 screened. We analyzed 579 biological samples (hair, nail, and urine) from Shahpur and found that 82, 89, and 91¿% of hair, nail, and urine, respectively, had arsenic above the normal levels, indicating many people in the study area are sub-clinically affected. Arsenical neuropathy was observed in 48¿% of 102 arsenicosis patients. The study also found that arsenic exposed women with severe skin lesions had adversely affected their pregnancies. The carcinogenic and non-carcinogenic risks were also estimated based on the generated data. Safe drinking water supply is urgently required to combat arsenic situation in affected villages of Shahpur.

Chemical methods have been used for the remediation of arsenic (As)-contaminated water; however, ecological consequences of these methods have not been properly addressed. The present study evaluated the effects of the Fe-oxide-coated sand (IOCS) remediation method on As toxicity to freshwater organisms (Lemna disperma, Chlorella sp. CE-35, and Ceriodaphnia cf. dubia). The As removal efficiency by IOCS decreased substantially with time. The IOCS remediation method was less effective at suppressing the toxicity of AsV than AsIII to L. disperma but was highly effective in reducing both the AsIII and AsV toxicity to C. cf. dubia. The growth of Chlorella sp. was significantly higher (p < 0.05) in remediated and pre-remediated water than in controls (non-As-contaminated filtered Colo River water) for AsIII, while the opposite was observed for AsV, indicating that AsV is more toxic than AsIII to this microalga. Although the IOCS can efficiently remove As from contaminated water, residual As and other constituents (e.g. Fe, nitrate) in the remediated water had a significant effect on freshwater organisms.

This study determined the total and speciated arsenic (As) concentrations and other health-related water quality parameters for unraveling the health risk of As from drinking water to humans. Groundwater samples (n = 62) were collected from three previously unexplored rural areas (Chichawatni, Vehari, Rahim Yar Khan) of Punjab in Pakistan. The mean and median As concentrations in groundwater were 37.9 and 12.7 µg¿L-1 (range = 1.5¿201 µg¿L-1). Fifty three percent groundwater samples showed higher As value than WHO safe limit of 10 µg¿L-1. Speciation of As in groundwater samples (n = 13) showed the presence of inorganic As only; arsenite (As(III)) constituted 13%¿67% of total As and arsenate (As(V)) ranged from 33% to 100%. For As health risk assessment, the hazard quotient and cancer risk values were 11¿18 and 46¿600 times higher than the recommended values of US-EPA (i.e., 1.00 and 10-6, respectively). In addition to As, various water quality parameters (e.g., electrical conductivity, Na, Ca, Cl-, NO3-, SO42-, Fe, Mn, Pb) also enhanced the health risk. The results show that consumption of As-contaminated groundwater poses an emerging health threat to the communities in the study area, and hence needs urgent remedial and management measures.

Arsenic bioaccumulation in rice grain has been identified as a major problem in Bangladesh and many parts of the world. Rice is one of the crops affected by arsenic due to its semiaquatic nature. A field study was conducted to investigate the effect of variety and water management on the bioaccumulation of arsenic within the rice plants in different rice cultivars. Ten of the most popularly grown BRRI, BINA and local rice cultivars were screened for susceptibility to arsenic under varying irrigation options. Total grain arsenic accumulation was higher in the plants grown in high soil arsenic in combination with conventional irrigation practice. Results showed that appropriate water management practice and suitable variety resulted in a reduction of grain arsenic level around 39% in addition to increase grain yield around 38%.

The study assesses the concentrations of Arsenic (As), Cadmium (Cd) and lead (Pb) in home-garden vegetables from a severely As-contaminated area of Bangladesh. The mean concentrations of As, Cd and Pb in 87 vegetables were 113 %mu;g/kg, 134 %mu;g/kg and 3100 %mu;g/kg, respectively. The daily total consumption of As, Cd and Pb from vegetables alone for adult was 18 %mu;g, 22 %mu;g and 440 %mu;g, respectively. Vegetables alone did not contribute sufficiently enough to exceed Provisional Maximum Tolerable Daily Intake (PMTDI) values for Cd except for Pb. © 2012 Taylor & Francis Group.