Appraisal of probabilistic levels of toxic metals and health risk in cultivated and marketed vegetables in urban and peri-urban areas of Delhi,India

A total of six vegetables (S. tuberosum, D. carota, S. lycopersicum, A. esculentus, S. oleracea and B. juncea) were analysed for five heavy metals (As, Cd, Cr, Hg, and Pb) to evaluate the contamination load in vegetables collected from five cultivated and two market sites (n = 504) at Delhi, India. The irrigation water samples and soil samples (n = 180) were only collected from cultivated sites. The results showed that the concentration of heavy metals in soil and water samples were well below the permissible level except for Cd 0.001–0.013 µg g⁻¹. Similarly, the concentration of Cd (>0.20 µg g⁻¹) was detected higher in all investigated vegetables except for tomato. The evaluation index value was highest for spinach and lowest for tomato. The transfer factor values and metal pollution index was maximum in spinach and okra. Principal component analysis (PCA), Tukey’s HSD (Honestly Significant Difference) test, and one-way and two-way ANOVA (Analysis of Variance) were also applied to statistically analyse the results.     

Toxicity of lead, cadmium and mercury on embryogenesis, survival, growth and metamorphosis of Meretrix meretrix larvae

In order to assess the toxicity of heavy metals on the early development of Meretrix meretrix, the effects of mercury (Hg), cadmium (Cd) and lead (Pb) on embryogenesis, survival, growth and metamorphosis of larvae were investigated. The EC₅₀ for embryogenesis was 5.4 μg l⁻¹ for Hg, 1014 μg l⁻¹ for Cd and 297 μg l⁻¹ for Pb, respectively. The 96 h LC₅₀ for D-shaped larvae was 14.0 μg l⁻¹ for Hg, 68 μg l⁻¹ for Cd and 353 μg l⁻¹ for Pb, respectively. Growth was significantly retarded at 18.5 μg l⁻¹ (0.1 μM) for Hg, 104 μg l⁻¹ (1 μM) for Cd and 197 μg l⁻¹ (1 μM) for Pb, respectively. The EC₅₀ for metamorphosis, similar to 48 h LC₅₀, was higher than 96 h LC₅₀. Our results indicate that the early development of M. meretrix is highly sensitive to heavy metals and can be used as a test organism for ecotoxicology bioassays in temperate and subtropical regions.     

Effects of environmental metals on mitochondrial bioenergetics of the CD-1 mice pancreatic beta-cells

Environmental metals are believed to have diabetogenic effects without any clear underlying mechanisms. The study investigated the effects of metals, lead (Pb), mercury (Hg), cadmium (Cd), and molybdenum (Mo), on the bioenergetics of isolated pancreatic β-cells from CD-1 mice via different functional and structural techniques. The tested metals caused significant decrease in ATP production in concentration and exposure duration-dependent pattern; Cd was the most potent cytotoxic metal. In ATP assay estimated effective concentration 50 (EC50) (25, 40, 20, and 100 μM for Pb, Hg, Cd, and Mo, respectively), the metals also significantly inhibited the glucose-stimulated insulin secretion (GSIS), mitochondrial complexes activity, mitochondrial membranes potential, and oxygen consumption rates of the treated cells with parallel increases in their lactate production and in the mitochondrial swelling and permeation of their inner mitochondrial membranes to potassium (K⁺) and hydrogen (H⁺) ions. In addition, Cd, Pb, and Hg produced significant increases in mitochondrial membrane fluidity (MMF) with significant decreases in saturated/unsaturated fatty acid ratios. In 10 μM concentration, away from Mo, the three metals showed inhibitory effects on the mitochondrial functions to variable degrees. Only Cd showed significant effect on MMF and fatty acid ratios at a concentration of 10 μM. In conclusion, the tested metals significantly affected the bioenergetics of the pancreatic β-cells with significant effect on GSIS. Cd showed the most significant functional and structural effects on their mitochondria followed by Pb, then Hg, while Mo was almost safe up to 10 μM concentration. Hence, bioenergetic mitochondrial disruption can be considered as an underlying mechanism of the diabetogenic effects of the tested metals.     

Concurrent removal of Cr(III), Cu(II), and Pb(II) ions from water by multifunctional TiO2/Alg/FeNPs beads

The use of multifunctional materials for water remediation is a modern approach where adsorption phenomena and heterogeneous photocatalysis can be applied for the removal of pollutants. Since the ideal remediation system should be able to remove both organic and inorganic pollutants, a crucial aspect to consider is the knowledge of operational parameters affecting the removal process, especially when heavy metal ions are present in concoction as in real systems. Given the proven efficiency of multifunctional TiO₂/Alg/FeNPs magnetic beads for the removal of model organic pollutants, this study investigated the possibility to exploit such system also for the removal of mixed heavy metals (MHM), specifically Cr(III), Cu(II), and Pb(II) ions, under ultraviolet irradiation at a wavelength of 254 nm. After a preliminary screening on the optimal catalyst loading, operating parameters such as the initial concentration of metal ions, contact and irradiation time, and pH were investigated to optimize the removal of metal ions using response surface methodology (RSM) via Box–Behnken design. Starting from a MHM solution containing 44 ppm of each metal ion, the removal of Pb(II), Cr(III), and Cu(II) ions in the aqueous solution was nearly completed (>98.4%) for all three ions within 72 min of irradiation at almost neutral pH (pH = 6.8). The stability of TiO₂/Alg/FeNPs was confirmed by retrieving and reusing the beads in three consecutive cycles of heavy metals removal without observing significant changes in catalyst efficiency.     

Genome sequencing reveals mechanisms for heavy metal resistance and polycyclic aromatic hydrocarbon degradation in Delftia lacustris strain LZ-C

Strain LZ-C, isolated from a petrochemical wastewater discharge site, was found to be resistant to heavy metals and to degrade various aromatic compounds, including naphenol, naphthalene, 2-methylnaphthalene and toluene. Data obtained from 16S rRNA gene sequencing showed that this strain was closely related to Delftia lacustris. The 5,889,360 bp genome of strain LZ-C was assembled into 239 contigs and 197 scaffolds containing 5855 predicted open reading frames (ORFs). Among these predicted ORFs, 464 were different from the type strain of Delftia. The minimal inhibitory concentrations were 4 mM, 30 µM, 2 mM and 1 mM for Cr(VI), Hg(II), Cd(II) and Pb(II), respectively. Both genome sequencing and quantitative real-time PCR data revealed that genes related to Chr, Czc and Mer family genes play important roles in heavy metal resistance in strain LZ-C. In addition, the Na⁺/H⁺ antiporter NhaA is important for adaptation to high salinity resistance (2.5 M NaCl). The complete pathways of benzene and benzoate degradation were identified through KEGG analysis. Interestingly, strain LZ-C also degrades naphthalene but lacks the key naphthalene degradation gene NahA. Thus, we propose that strain LZ-C exhibits a novel protein with a function similar to NahA. This study is the first to reveal the mechanisms of heavy metal resistance and salinity tolerance in D. lacustris and to identify a potential 2-methylnaphthalene degradation protein in this strain. Through whole-genome sequencing analysis, strain LZ-C might be a good candidate for the bioremediation of heavy metals and polycyclic aromatic hydrocarbons.

     

Poly (acrylamide acrylic acid)/Baghouse dust magnetic composite hydrogel as an efficient adsorbent for metals and MB; synthesis,characterization, mechanism,and statistical analysis

Steel manufacturing waste-based magnetic composite hydrogel was fabricated. Acrylamide-acrylic acid copolymer (AA) was intercalated to baghouse dust (BHD) to obtain (AABHD) composite. The synthesized AABHD composite was used for the removal of Pb (II), Cd (II), and MB from aqueous media. The AABHD composite was characterized using SEM, BET, XRD, TGA, FTIR, XPS, and zeta potential. The impact of various parameters on the adsorption performance of the AABHD hydrogel for MB, Cd (II), and Pb (II) was evaluated. The experimental kinetics of MB and metals followed the second-order model, where film diffusion was the dominating mechanism. The isotherm study revealed that equilibrium results of MB follow Dubinin-Radushkevich (D-R), while metals were well described by Freundlich. AABHD exhibited maximum adsorption efficiencies of 96, 98, and 99 percent and capacities of 503, 236, and 476 mg/g for MB, Cd (II), and Pb (II), respectively. The thermodynamic outcome indicated spontaneous and favorable adsorption of MB and metals. The regeneration study verified the high reusability of the AABHD composite for MB and metals. The obtained findings showed that the AABHD could be efficiently employed for the simultaneous elimination of MB and metal ions from wastewater.     

Suitability of <Emphasis Type="Italic">Daphnia similis</Emphasis> as an alternative organism in ecotoxicological tests: implications for metal toxicity

The acute toxicity of metals to Daphnia similis was determined and compared to other daphnid species to evaluate the suitability of this organism in ecotoxicology bioassays. To verify the performance D. similis in toxicity tests, we also investigated the effect of Pseudokirchneriella subcapitata at 1 × 10⁵ and 1 × 10⁶ cells ml⁻¹ on Cd and Cr acute toxicity to the cladoceran. Daphnid neonates were exposed to a range of chromium and cadmium concentrations in the absence and presence of the algal cells. Metal speciation calculations using MINEQL⁺ showed that total dissolved metal concentrations in zooplankton culture corresponded to 96.2% free Cd and 100% free Cr concentrations. Initial total dissolved metal concentrations were used for 48 h-LC₅₀ determination. LC₅₀ for D. similis was 5.15 × 10⁻⁷ mol l⁻¹ dissolved Cd without algal cells, whereas with 1 × 10⁵ cells ml⁻¹, it was significantly higher (7.15 × 10⁻⁷ mol l⁻¹ dissolved Cd). For Cr, the 48 h-LC₅₀ value of 9.17 × 10⁻⁷ mol l⁻¹ obtained for the cladoceran in tests with 1 × 10⁶ cells ml⁻¹ of P. subcapitata was also significantly higher than that obtained in tests without algal cells (5.28 × 10⁻⁷ mol l⁻¹ dissolved Cr). The presence of algal cells reduced the toxicity of metals to D. similis, as observed in other studies that investigated the effects of food on metal toxicity to standard cladocerans. Comparing our results to those of literature, we observed that D. similis is as sensitive to metals as other standardized Daphnia species and may serve as a potential test species in ecotoxicological evaluations.     

Multivariate analysis combined with GIS to source identification of heavy metals in soils around an abandoned industrial area,Eastern China

Heavy metals in soils polluted by industrial production are a meaningful topic worldwide. The purpose of this study is to understand the pollution status and spatial distribution of heavy metals in soils. The result can help decision-makers apportion possible soil heavy metals sources and formulate effective pollution control policies. In this paper, 155 soil samples (0–20 cm) were collected and analyzed for eight heavy metals (Cd, Hg, As, Cu, Pb, Cr, Zn, and Ni) from an abandoned industrial area of Tong County, located in Jiangsu Province of Eastern China. The multivariate analysis (including I_geo, E_i/RI, EF, PCA, and CA) and geostatistics (GIS) were used to assess the enrichment level and pollution level of soil heavy metals and identify their sources. The results indicated that eight heavy metals in soils had moderate variations, with CVs ranging from 19.63 to 63.34 %. The pollution level of I_geo of soil heavy metals decreased in the order of Cd~Zn > Cu > Hg~As~Pb~Cr~Ni. The enrichment level of soil heavy metals decreased in the order of Cd > Zn > Hg > Cu > Pb > Ni > As > Cr. According to the E_i, except Cd and Hg were in the significant and moderate ecological risk levels respectively, other soil heavy metals were in the clean or light ecological risk levels, the level of potential ecological risk (RI) of the whole industrial area was moderate. Finally, the source identification of soil heavy metals indicated that Cd and Zn were primarily controlled by human activities, and Hg and Cu were controlled by natural and anthropogenic sources, and As, Pb, Cr, and Ni were mainly controlled by soil parent materials.     

微波消解-ICP-MS法测定天舒胶囊中5种重金属元素

目的：使用电感耦合等离子体质谱（ICP-MS）仪,建立天舒胶囊中Cu、As、Pb、Cd、Hg 5种重金属元素的测定方法。方法：样品经过微波消解处理后,采用外标法,以ICP-MS进行测定。结果：各元素线性关系良好（r＞0.9990）,最低检测限为（0.0014~0.8237）μg·L-1,回收率为98.4%~114.1%。结论：该方法准确、简便、快速、灵敏,适用于天舒胶囊内容物中重金属的含量测定。     

Potential risk assessment of trace metals accumulation in food,water and edible tissue of rainbow trout (Oncorhynchus mykiss) farmed in Haraz River,northern Iran

This study focuses on the extent of Zn, Cu, Ni, Cd and Pb bioaccumulation in water, fish feed and the muscles of 40 rainbow trout (Oncorhynchus mykiss) from four farmsalong Haraz River, Mazandaran Province, north of Iran. The dependence of bioaccumulation with food chain and environmental heavy metals concentration was specifically addressed. The potential human health risks due to consumption of rainbow trout have been assessed by estimated daily intake (EDI) and target hazard quotient (THQ) of aforementioned metals. The detected concentration ranges of the elements in the muscles, reported as μg.g^?1?dry weight, were as following: Zn (13.92–15.92), Cu (0.54–0.74), Ni (0.12–0.26), Cd (0.008–0.01) and Pb (0.25–0.57). The rank order of the levels of the heavy metals was: in edible tissue Zn?>?Cu?>?Pb?>?Ni?>?Cd; in water Pb?>?Zn?>?Cu?>?Ni?>?Cd; in fish feed Pb?>?Zn?>?Ni?>?Cu?>?Cd. In general, the concentrations of all target metals were positively correlated with fish feed contents, whereas negative correlations were observed between the metal concentrations and water. Risk assessments suggested that there isn’t potential ecological and human health risk.     

Risk assessment of heavy metals in honey consumed in Zhejiang province,southeastern China

The levels of copper (Cu), zinc (Zn), cadmium (Cd), lead (Pb), arsenic (As), and mercury (Hg) in eight types of honey collected in China were determined. The average concentrations of the six heavy metals in the honey samples were 46.18, 1329.5, 1.34, 33.98, 13.44, and 1.65 μg kg⁻¹, respectively. All these values were below the maximum allowable contaminant levels in foods (GB2762-2005) and honey (GB14963-2011) in China. The hazard quotients of individual heavy metals and the hazard index of all six heavy metals were far below one, indicating no chronic-toxic risk from these metals for the inhabitants of Zhejiang under the current consumption rates of honey. However, the carcinogenic risk of As for the female inhabitants in Zhejiang exceeded the acceptable level of 10⁻⁴. Therefore, As is the most concerning heavy metal in honey.     

Combined toxicity of heavy metal mixtures in liver cells

With rapid industrialization, China is now facing great challenges in heavy metal contamination in the environment. Human exposure to heavy metals through air, water and food commonly involves a mixture consisting of multiple heavy metals. In this study, eight common heavy metals (Pb, Cd, Hg, Cu, Zn, Mn, Cr, Ni) that cause environmental contamination were selected to investigate the combined toxicity of different heavy metal mixtures in HL7702 cells. Toxicity (24 h LC₅₀) of each individual metal on the cells ranked Hg > Cr = Cd > Cu > Zn > Ni > Mn > Pb; toxicity of the different mixtures ranked: M5 > M3PbHgCd > M5+Mn > M5+Cu > M2CdNi > M4A > M8‐Mn > M8 > M5+Zn > M4B > M8‐Cr > M8‐Zn > M8‐Cu > M8‐Pb > M8‐Cd > M8‐Hg > M8‐Ni > M3PbHgNi > M3CuZnMn. The cytotoxicity data of individual metals were successfully used to build the additive models of two‐ to eight‐component metal mixtures. The comparison between additive model and combination model or partly additive model was useful to evaluate the combined effects in mixture. Synergistic, antagonistic or additive effects of the toxicity were observed in different mixtures. These results suggest that the combined effects should be considered in the risk assessment of heavy metal co‐exposure, and more comprehensive investigations on the combined effects of different heavy metal mixtures are needed in the future. Copyright © 2016 John Wiley & Sons, Ltd.     

Development of a free beta-galactosidase in vitro test for the assessment of heavy metal toxicity

The effect of heavy metals and organic compounds on the activity of the enzyme beta-galactosidase in a standardized bioassay has been evaluated, considering future applications in environmental monitoring. The tests were done using a commercial extract of a hydrolase from the eukaryote yeast Kluyveromyces lactis and o-nitrophenyl-beta-D-galactopyranoside (ONPG) as substrate. The enzyme was exposed to Cr(VI), Cd(II), Cu(II), Ni(II), Pb(II), Hg(II), phenol, sodium dodecyl sulfate, methanol and pentachlorophenol for 5, 15, 30, and 60 min. According to the results, a 15 min exposure time was considered optimum for the performance of the assay. Results of tests with metals showed IC50 values ranging between 9.25mg/L for Cd(II) and 0.015mg/L for Hg(II), with an order of sensitivity of: Cd(II) < Ni(II) < Cr(VI) = Pb(II) < Cu(II) < Hg(II). Sensitivity to organic compounds ranged from 200 to 4,000 mg/L, showing a higher specificity to heavy metals. The present in vitro free enzyme test showed a similar behavior to other tests based on beta-galactosidase such as the MetPlate. Furthermore, when compared to data from the literature on acute toxicity assays currently used in environmental assessment, test results show good agreement regarding the sensitivity to metals. After standardization, the proposed test could be used as a rapid and low-cost assay when evaluating biological effects of heavy metals in monitoring programs.     

Pod razor (Ensis siliqua) shell powder as cost-effective biomineral for removal of nickel(II), copper(II) and zinc(II) from artificially contaminated industrial wastewater

The removal of Ni(II), Cu(II) and Zn(II) from aqueous model solutions and real wastewater samples by using pod razor (Ensis siliqua) shell powder has been investigated under several conditions such as heavy metal concentrations, pH, contact time, powder dosage. It was found that the removal of heavy metals was dependent on the dose of the biomineral and contact time. The results showed that this low-cost material can be fruitfully used for the removal of heavy metal ions such as Ni(II), Cu(II) and Zn(II) below concentration of 200 mg/L applying a shell powder dose of 1.2–4 g/L. The minimal dose for removal of Cu(II) and Zn(II) from industrial wastewater was found to be 1.2 g/L, while for Ni this value amounted to 1.6 g/L. The contact time necessary for quantitative removal was found to be 30–60 min and the optimum initial pH range was between 4 and 5.     

Ecological risk of heavy metals in sediments of the Luan River source water

Distribution and characteristics of heavy metals enrichment in sediment were surveyed including the bio-available form analyzed for assessment of the Luan River source water quality. The approaches of sediment quality guidelines (SQG), risk assessment code and Hakanson potential ecological risk index were used for the ecological risk assessment. According to SQG, The results show that in animal bodies, Hg at the sampling site of Wuliehexia was 1.39 mg/kg, Cr at Sandaohezi was 152.37 mg/kg and Cu at Hanjiaying was 178.61 mg/kg exceeding the severe effect screening level. There were 90% of sampling sites of Cr and Pb and 50% sites of Cu exceeded the lowest effect screening level. At Boluonuo and Wuliehexia, the exchangeable and carbonate fractions for above 50% of sites were at high risk levels and that for above 30% of sites at Xiahenan and Wulieheshang were also at high risk levels. Other sites were at medium risk level. Compared to soil background values of China, Hg and Cd showed very strong ecological risk, and the seven heavy metals of Hg, Cd, Cu, As, Pb, Cr, Zn at ecological risk levels were in the descending order. The results could give insight into risk assessment of environmental pollution and decision-making for water source security.     

Nickel adsorption from aqueous solution using lemon peel biomass chemically modified with TiO2 nanoparticles

Adsorption technique has attracted considerable attention as a promising alternative for reducing heavy metal ions in water sources. This work is focused on the adsorption of nickel ions using lemon peel biomass chemically modified with titanium dioxide (TiO₂) nanoparticles through siloxane bonds. The biomass was characterized by FT-IR and compositional analyses to identify functional groups and elemental composition. From these measurements, it was observed peaks at 1741, 1328, and 1229 cm^?1, characteristics of CO, C–O, and C–H stretching bands, respectively. These organic bonds can be related to the existence of cellulose, lignin, and pectin biopolymers, which are present in the lemon peel biomass, as observed from the compositional analyses. After grafting TiO₂ nanoparticles onto lemon peel biomass surface, it was observed from FTIR the presence of vibrational bands at 1524, 1054, and 943 cm^?1, characteristics of –Ti-O-C, –Si-O-Si, and –Ti-O-Si functional groups. Additionally, the morphology and elemental composition of the lemon peel biomass modified with the titanium dioxide (TiO₂) nanoparticles were determined by SEM microscope, observing the presence of C, O, Ti, and Si atoms from the EDS mapping. Batch adsorption experiments were carried out to determine the effect of pH and biomass particle size on adsorption of Ni (II) ions from aqueous solution. From these experiments, maximum adsorption of Ni (II) ions of 78 ± 0.2% was obtained at pH 6.0, while no significant effects were observed for biomass particle size. Furthermore, the modification of biomass with TiO₂ nanoparticles increased up to 90 ± 0.1% the Ni (II) ions adsorption, suggesting the potential of the biomass modified with metal oxide nanoparticles for removal of heavy metal ions.     

Evaluation of adsorption capacities of nanocomposites prepared from bean starch and montmorillonite

To date, many efforts have been made in order to develop novel cost-efficient materials that can be used to remove heavy metal ions from aqueous solution. The aim of this work was to evaluate the adsorption capacity of nanocomposites prepared from starch and sodium montmorillonite (starch/Na-MMT). To this end, nanocomposites with different starch-to-nanoclay ratio (SN) of 5:1, 10:1 and 10:3 were prepared by intercalation technique in acetic acid solution and used for nickel and cobalt uptake. The characterization techniques of Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) were conducted to determine physicochemical and morphological properties of nanocomposites as well as bean starch. The initial concentration of metal ions, pH and SN ratios were varied to assess how well the starch/Na-MMT nanocomposites could remove cobalt and nickel from aqueous solutions. Experimental results were used to calculate parameters of the Langmuir and Freundlich isotherms. It was found that pH = 4.5, C_o = 100 ppm (metal concentration in solution), and SN = 10:1 were the most suitable conditions based on the removal yield (97.1%) and adsorptive favourability for nickel ions. For cobalt, the highest removal yield (78.07%) was achieved using pH = 6, C_o = 140 ppm and SN = 10:3. The fitting of the data to the Langmuir and Freundlich isotherms indicated a multilayer adsorption process for both heavy metals. These results showed that the nanocomposite starch/Na-MMT exhibited attractive adsorption properties for its application during wastewater remediation. The incorporation of Na-MMT in the bean starch matrix is strongly encouraged for nickel uptake due to the adsorption efficiencies increase by 35% compared to the unmodified starch.     

Non-carcinogenic risk assessment of eight metals in the source groundwater of Shaying River Basin

Because of serious pollution of river water, people living along the Shaying River in China exploit the groundwater as a drinking water resource. Various pollutants including heavy metals have been detected in the groundwater at depths up to 200 m. To perform a non-carcinogenic risk assessment, the hazard index (HI) was determined for several metals present in the groundwater. High resolution inductively coupled plasma–mass spectrometry and inductively coupled plasma–atomic emission spectroscopy were used to measure the levels of Hg, Fe, Mn, Zn, Cd, Cr, Cu and Pb in source groundwater of eight tap water treatment plants (WTPs) during a 3-year period (2007–2009). Zn was present at the highest concentration of up to 101.2 μg l⁻¹ and Cd contributed the most (57.8%) to the HI in the WTPs, followed by Mn (14.3%) and Cr (13.1%). Both hazard quotients of individual metals and HI of total non-carcinogenic risk in each WTP were below 1.0, suggesting that the water posed negligible health risk on local residents. Temporal and spatial comparisons showed that high HIs tend to occur in low water periods (i.e., summer), and the City Pressure Station (Fuyang City) had the highest HI, followed by Yingnan Pressure Station (Yingnan Country) and Taihe WTP (Taihe Country). This study provides benchmark information useful for regulatory authorities to control the discharge of metals into the Shaying River Basin, and serves as a basis for comparison to other river systems in the world.     

Adsorptive removal of Cd (II) using oil palm empty fruit bunch-based charcoal/chitosan-EDTA film composite

Oil palm empty fruit bunch (OPEFB) is a solid waste abundantly produced by the palm oil industry. This study aimed to prepare a film adsorbent from OPEFB-based charcoal (OC), embedded into chitosan-ethylenediaminetetraacetic acid (EDTA) matrix (OC/Chi-EDTA) through a simple phase inversion technique for Cd (II) removal. Based on the tensile strength (20.4 kgf/mm²) and adsorption capacity (66.6 mg/g), the material with 0.85 : 0.1: 0.15 was selected as the best film adsorbent using simple additive weighting. Further, the sample was characterized for its functional group, morphology, crystallinity, and thermal behavior. The characterizations revealed the successful preparation of OC/Chi-EDTA with advantageous properties for Cd (II) adsorptive removal such as rough surface morphology and amorphous structure (crystallinity = 41.02). Good thermal stability of OC/Chi-EDTA was also suggested by the T_peak of the first composite degradation at 298.97°C. At equilibrium, the adsorption isotherm best fitted with the Langmuir isotherm model (R² = 0.992; root-mean-square error = 2.75), where the maximum adsorption capacity was 283.33 mg/g. Investigation on the adsorption mechanisms found that electrostatic attraction and complexation were responsible for the Cd (II) uptake. At the optimum conditions (contact time = 120 min; pH 7), the adsorption capacity was recorded to be 67.2 mg/g with a removal efficiency of 99.56%. Regeneration studies suggested that OC/Chi-EDTA can be used up to four cycles (removal efficiency > 75%). In conclusion, the OC has been successfully embedded into chitosan-EDTA matrix resulting in a film adsorbent that could perform a high Cd (II) uptake.     

Health risk assessment of heavy metals via dietary intake of foodstuffs from the wastewater irrigated site of a dry tropical area of India

The present study was conducted to assess the risk to human health by heavy metals (Cd, Cu, Pb, Zn, Ni and Cr) through the intake of locally grown vegetables, cereal crops and milk from wastewater irrigated site. Milk is not directly contaminated due to wastewater irrigation, but is an important route of food chain transfer of heavy metals from grass to animals. Heavy metal concentrations were several fold higher in all the collected samples from wastewater irrigated site compared to clean water irrigated ones. Cd, Pb and Ni concentrations were above the ‘safe’ limits of Indian and WHO/FAO standards in all the vegetables and cereals, but within the permissible limits in milk samples. The higher values of metal pollution index and health risk index indicated heavy metal contamination in the wastewater irrigated site that presented a significant threat of negative impact on human health. Rice and wheat grains contained less heavy metals as compared to the vegetables, but health risk was greater due to higher contribution of cereals in the diet. The study suggests that wastewater irrigation led to accumulation of heavy metals in food stuff causing potential health risks to consumers.