A study of ground water contamination by arsenic in the residential area of Behala, Calcutta due to industrial pollution

Evaluation of groundwater quality with multi-source pollution based on source identification and health risks

Groundwater is a crucial water supply source in Chengdu City, western China, a region experiencing significant water scarcity. The sources of inorganic pollutants in groundwater and their potential health risks are of great concern. In this study, based on 156 groundwater samples collected in 2021 in the study area were analyzed for hydrochemical characterization and controlling factors. The Positive Matrix Factorization (PMF) model was used for contaminant source analysis, and Monte Carlo Simulation (MCS) combined with the Health Risk Evaluation Model (HREM) was used to quantify the health risks. The results indicate that the groundwater in the study area is predominantly of the Ca·Na-SO4·HCO3, Ca·Na-HCO3·SO4 and Ca-HCO3·SO4 types, mainly influenced by the combination of evaporation-concentration-crystallization and rock leaching-weathering. K+, Na+, and Cl- mainly originate from the weathering and dissolution of potassium feldspar and rock salt, while Ca2+, Mg2+, HCO3-, and SO42- primarily come from the weathering and dissolution of sulfate minerals. The main sources of groundwater pollution and their contributions are as follows: domestic pollution (25.6 %), dissolution-filtration-evaporation-concentration action (22.8 %), hydrogeochemical evolution (15.8 %), water-rock interactions (12.8 %), primary geologic context (12.1 %), and agricultural non-point source pollution (11.0 %). Cl- and As are the primary contributors to non-carcinogenic and carcinogenic risks, respectively. Non-carcinogenic risks are below USEPA standards, while the average carcinogenic risk for arsenic exceeded the maximum acceptable risk level thresholds by 23 and 109 times for adults and children, respectively. Non-carcinogenic and carcinogenic health risks were mainly influenced by pollutant concentrations. The primary geological background and domestic pollution contributed the most to the non-carcinogenic risk for adults (50.3 %) and children (77.1 %), and 38.2 % and 10.3 %, respectively. This study highlights the necessity of establishing a comprehensive groundwater pollution monitoring system, enhancing industrial waste management practices, and raising public awareness to mitigate contamination and ensure the sustainable use of groundwater resources in Chengdu City.

Co-exposure of nanoplastics and arsenic causes neurotoxicity in zebrafish (Danio rerio) through disrupting homeostasis of microbiota-intestine-brain axis

Nanoplastics (NPs) and arsenic (As) are toxic pollutants prevalent on the earth and have gained considerable attention in recent decades. Although numerous studies reported NPs and As can cause neurotoxicity there are still significant knowledge gaps in illustrating their combined toxicity and its mechanism. In this study, the co-exposure of environmentally relevant concentrations of NPs and As caused neurobehavioral toxicity in zebrafish, as evidenced by reduced swimming ability, anxiety and impaired short-term learning memory. Potentially, its toxicity mechanism is through disrupting the homeostasis of microbiota-intestine-brain axis in zebrafish. Specifically, the co-exposure reduced the 5-hydroxytryptamine (5-HT) production in intestine, which led to lower levels of 5-HT transported by the blood circulation to the brain. Ultimately, neurobehavior was adversely affected by the reduced binding of 5-HT to its receptors. Intestine, the primary source of 5-HT, its impaired health (aggravation in oxidative stress, mitochondrial damage and histopathological alterations) induced the dysregulation in the 5-HT system, which may be induced by the increased accumulation of As in the intestine by the co-exposure. Besides, the reduced 5-HT levels were correlated with decreased Firmicutes and Protecbacteria and increased Actinobacteriota and Chloroflexi in intestines. Potentially, intestinal microbiota adversely regulates the intestine-brain axis by reducing SCFAs levels. Thus, the alteration of intestinal microbiota structure may be the other reason for the dysregulation of intestine-brain axis. In summary, co-exposure of NPs and As induced neurobehavior toxicity probably through disrupting the homeostasis of microbiota-intestine-brain axis. This study provides insights into assessing the environmental health risks of the pollution of NPs and As to aquatic organisms.

Nanoplastics promote arsenic-induced ROS accumulation, mitochondrial damage and disturbances in neurotransmitter metabolism of zebrafish (Danio rerio)

As a carrier, nanoplastics (NPs) can adsorb other toxic substances and thus modify their biological toxicity. Numerous studies have investigated the neurotoxic of high concentrations of arsenic (As, 2.83 mg/L-5 mg/L). However, it is still unknown whether the relatively low environmentally relevant concentrations of As (200 μg/L) can damage the structure and function of fish brains with the presence of NPs. In this study, zebrafish were exposed to polystyrene NPs, As and their mixture for 30 days respectively. Firstly, we found that the presence of NPs promoted the accumulation of As in zebrafish brains. Thereby the co-exposure of NPs and As further promoted the production of reactive oxygen species (ROS) in zebrafish brains compared with the single exposure of NPs or As, resulting in severe oxidative stress. Moreover, accumulated ROS directly damaged the mitochondrial membrane and mtDNA in zebrafish brains. Moreover, the mitochondrial damage was further aggravated due to inhibited mitochondrial fusion and activated mitochondrial division and mitophagy. Ultimately, the co-exposure led to mitochondrial damage in the zebrafish brain. Damaged mitochondria may not meet the high energy metabolic requirement for neuronal function. As a result, the normal function of nerve cells was adversely affected and eventually cell apoptosis may occur. Besides, the co-exposure caused more significant structural alterations in zebrafish brain tissue. Finally, the co-exposure of NPs and As caused abnormal biosynthesis and degradation of dopamine and acetylcholine. These resulted in decreased dopamine levels and increased acetylcholine levels in zebrafish brains. In conclusion, the presence of NPs promoted the accumulation of As, thereby inducing severe oxidative stress, which caused structural alterations and mitochondrial damage in the zebrafish brain, thus disordering neuromodulation, which may ultimately cause neurological dysfunction in zebrafish. This study will provide a risk assessment for evaluating the biotoxicity of NPs and As to fish and even other animals.

Cl/Br mass ratio and water quality index from the Quaternary aquifer of south Bengal Basin in India

The purpose of this study is to identify suitable areas for the exploitation of groundwater for human consumption by analysing Cl/Br and other indicators of wastewater influence on groundwater quality in and around the twin megacities of Kolkata and Howrah, located on the complex deltaic system of south Bengal Basin in India. About 18%, 56.5%, 28% and 35.5% of the 287 groundwater samples comply with the Indian acceptable limits (ALs) of TDS, Cl, Fe and Mn, respectively. About 29% of the 279 samples analysed have Cl/Br < 268 where the excess Br is derived from organic degradation. About 30% samples have Cl/Br > 308 clustering mainly around a palaeo-channel indicating wastewater contamination. In addition to these, many samples have NO₃/Cl > 0.0002 and SO₄/Cl > 0.014, indicating that the groundwater is contaminated by wastewater from sewage and septic tank leakage. The concentrations of metals (Fe, Mn) and As are also higher than AL particularly on either side of the palaeo-channel, which may affect the human body functions. The localised recharge of wastewater also contains high SO₄. Sulphate reduction in the aquifer sequesters the As in groundwater into the neo-formed arsenopyrite. Based on the estimated water quality index, the groundwater samples have been classified into four types-highly suitable (28.17%), moderately suitable (23.94%), doubtful (15.85%) and unsuitable (32.04%) for drinking purpose. The first two types cover about 62% of the study area. But the highly urbanised area of Kolkata and Howrah city and the industrial areas in the southern fringe of Kolkata city have the latter two types of groundwater. The over-withdrawal of groundwater may expedite the quality deterioration of 'highly and 'moderately suitable water' of the study area into 'doubtful' and 'unsuitable for drinking' categories through mixing mechanism in the aquifer.

Various Natural and Anthropogenic Factors Responsible for Water Quality Degradation: A Review

Recognition of sustainability issues around water resource consumption is gaining traction under global warming and land utilization complexities. These concerns increase the challenge of gaining an appropriate comprehension of the anthropogenic activities and natural processes, as well as how they influence the quality of surface water and groundwater systems. The characteristics of water resources cause difficulties in the comprehensive assessment regarding the source types, pathways, and pollutants behaviors. As the behavior and prediction of widely known contaminants in the water resources remain challenging, some new issues have developed regarding heavy metal pollutants. The main aim of this review is to focus on certain essential pollutants’ discharge from anthropogenic activities categorized based on land-use sectors such as industrial applications (solid/liquid wastes, chemical compounds, mining activities, spills, and leaks), urban development (municipal wastes, land use practices, and others), and agricultural practices (pesticides and fertilizers). Further, important pollutants released from natural processes classified based on climate change, natural disasters, geological factors, soil/matrix, and hyporheic exchange in the aquatic environment, are also discussed. Moreover, this study addresses the major inorganic substances (nitrogen, fluoride, and heavy metals concentrations). This study also emphasizes the necessity of transdisciplinary research and cross-border communication to achieve sustainable water quality using sound science, adaptable legislation, and management systems.

Capture of Toxic Oxoanions from Water Using Metal-Organic Frameworks

The effective capture of common water contaminants using metal-organic frameworks (MOFs) presents a remedy for current environmental concerns arising from the pollution of water sources. The crystalline porous nature of MOFs, their high internal surface area, and exceptional tunability make them suitable candidates for sequestration and removal of pollutants. However, the efficiency of capture depends largely on the nature of the interactions between the anions and the MOF. In this work, to elucidate the host-guest interactions involved in the capture of such pollutants, we explore three characteristically different MOFs: ZIF-8, iMOF-2c, and MOF-74. We demonstrate by ab initio electronic structure calculations the importance of exploiting qualitatively different binding modes for strong host-guest interactions available in the selected MOFs. Our simulations reveal the relative performance of neutral and cationic adsorbents while underscoring the importance of employing MOFs containing open metal sites for the efficient uptake of anions.

Removal of decidedly lethal metal arsenic from water using metal organic frameworks: a critical review

Water contamination is worldwide issue, undermining whole biosphere, influencing life of a large number of individuals all over the world. Water contamination is one of the chief worldwide danger issues for death, sickness, and constant decrease of accessible drinkable water around the world. Among the others, presence of arsenic, is considered as the most widely recognized lethal contaminant in water bodies and poses a serious threat not exclusively to humans but also towards aquatic lives. Hence, steps must be taken to decrease quantity of arsenic in water to permissible limits. Recently, metal-organic frameworks (MOFs) with outstanding stability, sorption capacities, and ecofriendly performance have empowered enormous improvements in capturing substantial metal particles. MOFs have been affirmed as good performance adsorbents for arsenic removal having extended surface area and displayed remarkable results as reported in literature. In this review we look at MOFs which have been recently produced and considered for potential applications in arsenic metal expulsion. We have delivered a summary of up-to-date abilities as well as significant characteristics of MOFs used for this removal. In this review conventional and advanced materials applied to treat water by adsorptive method are also discussed briefly.

Arsenic, selenium, boron, lead, cadmium, copper, and zinc in naturally contaminated rocks: A review of their sources, modes of enrichment, mechanisms of release, and mitigation strategies

Massive and ambitious underground space development projects are being undertaken by many countries around the world to decongest megacities, improve the urban landscapes, upgrade outdated transportation networks, and expand modern railway and road systems. A number of these projects, however, reported that substantial portions of the excavated debris are oftentimes naturally contaminated with hazardous elements, which are readily released in substantial amounts once exposed to the environment. These contaminated excavation debris/spoils/mucks, loosely referred to as "naturally contaminated rocks", contain various hazardous and toxic inorganic elements like arsenic (As), selenium (Se), boron (B), and heavy metals like lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn). If left untreated, these naturally contaminated rocks could pose very serious problems not only to the surrounding ecosystem but also to people living around the construction and disposal sites. Several incidents of soil and ground/surface water contamination, for example, have been documented due to the false assumption that excavated materials are non-hazardous because they only contain background levels of environmentally regulated elements. Naturally contaminated rocks are hazardous wastes, but they still remain largely unregulated. In fact, standard leaching tests for their evaluation and classification are not yet established. In this review, we summarized all available studies in the literature about the factors and processes crucial in the enrichment, release, and migration of the most commonly encountered hazardous and toxic elements in naturally contaminated geological materials. Although our focus is on naturally contaminated rocks, analogue systems like contaminated soils, sediments, and other hazardous wastes that have been more widely studied will also be discussed. Classification schemes and leaching tests to properly identify and regulate excavated rocks that may potentially pose environmental problems will be examined. Finally, management and mitigation strategies to limit the negative effects of these hazardous wastes are introduced.

Groundwater Quality beneath an Asian Megacity on a Delta: Kolkata's (Calcutta's) Disappearing Arsenic and Present Manganese

Kolkata, the capital city of West Bengal, exploits groundwater for public water-supply. The groundwater has been reported to be widely polluted by arsenic (As). Analysis for As in 280 groundwaters from across Kolkata, failed to detect As concentrations >10 μg/L from natural processes. Arsenic concentrations between 10 and 79 μg/L found in 14 of the 280 groundwaters are remnant from a pollution-plume emanating from a single factory site where Paris Green, an arsenical pesticide, was manufactured between 1965 and 1985. In 45% of groundwaters sampled, concentrations of Mn exceed 0.4 mg/L, a putative health guideline value for drinking water. Sporadic minor hazards are posed by Pb > 10 μg/L introduced into groundwater from well-fittings, from 4% of groundwaters with F concentrations between 0.75 and 1 mg/L, and the 14% of groundwaters containing more than 500 mg/L Na, concentrations that might contribute to excessive daily intake of Na. Compounding hazards from As, F, Mn, Na, and Pb, shows that 64% of public wells and 40% of municipal wells supply groundwater of suspect quality. Groundwaters comply with WHO Guideline Values for drinking water in terms of Cr, Cu, Co, NO₂, NO₃, Sb, Se, and U. Aesthetic guideline values for Fe, Mn, SO₄, and Cl are exceeded for many groundwaters.

Rapid decadal evolution in the groundwater arsenic content of Kolkata, India and its correlation with the practices of her dwellers

Increasing arsenic contamination in the groundwater is one of the biggest environmental challenges that the Bengal delta is facing today. Groundwater is still the main source of water for a large number of population in this region and therefore, significant presence of toxic arsenic has a direct consequence on human lives here. Moreover, arsenic also enters into the food chain through the consumed agricultural products grown in this area. Therefore, acquiring knowledge about the ever-changing map of arsenic contamination and employing adequate protective measures are of utmost importance. Here, we present a comprehensive municipal ward-wise map of the arsenic content of the shallow groundwater table of Kolkata-the most important and highly population dense city of the delta. Comparison with previously available data reveals a rapid change and the grim situation for the city. Our study suggests that it should be an immediate task of the administration to extend treated water service to the whole population of the city for direct consumption, and artificial recharge and maximum rainwater replenishment need to be taken up with utmost urgency to avoid intrusion of toxicity in biological food chains via agricultural products. We hope our study would drive the city planners to reconsider the existing urbanization and development plans of all the cities, placed over arsenic-contaminated groundwater aquifers.

Plasma-aminothiols status and inverse correlation of total homocysteine with B-vitamins in arsenic exposed population of West Bengal, India

Chronic arsenic toxicity is a serious environmental health problem across the world. Bangladesh and India (particularly the state of West Bengal) are the worst affected countries with such problem. The present study reports plasma-aminothiols (p-aminothiols) like L-cysteine (L-Cys), cysteinyl glycine (Cys-gly), total homocysteine (t-Hcy) and glutathione (GSH) status, and the inverse relationship of t-Hcy with B-vitamins (B1, B6, B9 and B12) in arsenic exposed population of West Bengal, India. Reverse phase HPLC was used to measure p-aminothiols and serum B-vitamins in different arsenic exposed population. Arsenic in drinking water and urine were measured by flow injection analysis system - Atomic Absorption Spectrometry (FIAS-AAS) and Transversely heated graphite atomizer (THGA-AAS) techniques, respectively. Water arsenic exposure was >50 µg/L in 50% population, of which majority (33.58%) belong to the range of >50-500 µg/L and more than 8% were even >1000 µg/L. Urine arsenic (µg/g creatinine) levels increased with arsenic exposure. The variability among p-aminothiols was also observed with higher exposure to arsenic in drinking water. A significant difference between exposed and control population was noticed for plasma L-Cys. The difference of B-vitamins between the population exposed to <50 and >50 µg/L arsenic in drinking water was also found to be significant. B9 and B12 deficiency with increased consumption of arsenic in water corroborates the anemic conditions commonly observed among arsenic exposed population. The aminothiol status indicated oxidative stress in exposed population. This study demonstrated progressive increase in plasma t-Hcy as well as inverse relationships of serum B-vitamins with increased water arsenic concentration.

Semen characteristics and sperm morphology of Pistia stratiotes Linn. (Araceae) protected male albino rats (Wistar strain) exposed to sodium arsenite

BACKGROUND

Sodium arsenite has been proven to be abundant in nature and released into the environment through human activities, including agricultural and industrial processes. The objective of our study was to investigate the sperm protective potential of Pistia stratiotes Linn. in arsenic-treated rats.

METHODS

The sperm protective potential of P. stratiotes Linn. (Araceae) was carried out in arsenic-exposed rats using 24 male albino rats (225 to 228 g) aged between 14 and 16 weeks old. They were grouped into 4 (A-D), each group containing 6 rats. Group A animals were orally treated with 100 mg/kg ethanol leaf extract of P. stratiotes Linn. daily for 14 days; group B (sodium arsenite at 2.5 mg/kg body weight; positive control); group C (P. stratiotes extract for 14 days and single dose of sodium arsenite on day 14; group D (0.1 mL propylene glycol; negative control/vehicle).

RESULTS

Group B had a significantly lower (p<0.05) percentage sperm motility (26.7±6.67 %) while group A had a significantly (p<0.05) higher mean value (63.3±3.33 %) when compared across the groups. The sperm motility of rats in group D was significantly higher (p<0.05) than groups B and C. This implies that P. stratiotes extract had no adverse effect on sperm motility. The presence of P. stratiotes with sodium arsenite alleviated its harmful effect on sperm motility. The mean value obtained for sperm viability, semen volume and sperm count followed a similar pattern although the difference was not significant (p>0.05) for semen volume and the sperm count of rats across the groups. Total sperm abnormality was 10.44 and 14.27 % with the sodium arsenite treated group having the highest value when compared with groups A treated with P. stratiotes extract and D treated with propylene, although the differences were not significant (p>0.05).

CONCLUSIONS

The study concluded that ethanol leaf extract of P. stratiotes has no negative effect on sperm motility, viability and morphology and also protected spermatozoa against arsenic-induced reproductive toxicity in Wistar strain albino rats. Therefore, it may play an important role in the protection of populations with chronic sodium arsenite exposure.

Integrated Health Risk Assessment of Heavy Metals in Suxian County, South China

The purpose of this study was to assess soil heavy metal contamination and the potential risk for local residents in Suxian county of Hunan Province, southern China. Soil, rice and vegetable samples from the areas near the mining industrial districts were sampled and analyzed. The results indicate that the anthropogenic mining activities have caused local agricultural soil contamination with As, Pb, Cu and Cd in the ranges of 8.47-341.33 mg/kg, 19.91-837.52 mg/kg, 8.41-148.73 mg/kg and 0.35-6.47 mg/kg, respectively. GIS-based mapping shows that soil heavy metal concentrations abruptly diminish with increasing distance from the polluting source. The concentrations of As, Pb, Cu and Cd found in rice were in the ranges of 0.02-1.48 mg/kg, 0.66-5.78 mg/kg, 0.09-6.75 mg/kg, and up to 1.39 mg/kg, respectively. Most of these concentrations exceed their maximum permissible levels for contaminants in foods in China. Heavy metals accumulate to significantly different levels between leafy vegetables and non-leafy vegetables. Food consumption and soil ingestion exposure are the two routes that contribute to the average daily intake dose of heavy metals for local adults. Moreover, the total hazard indices of As, Pb and Cd are greater than or close to the safety threshold of 1. Long-term As, Pb and Cd exposure through the regular consumption of the soil, rice and vegetables in the investigated area poses potential health problems to residents in the vicinity of the mining industry.

Toxicological and phytoprotective effect of Keayodendron bridelioides and Monodora myristica extracts in Wister rats

OBJECTIVES

The potential toxicity of Keayodendron bridelioides (KB), Monodora myristica (MM) were examined, and phytoprotection of MM and KB stemming from their phytochemical contents against sodium arsenite (SA) induced clastogenicity in Wister's rat.

MATERIALS AND METHODS

Dose range studies of KB in rats, genotoxicity of MM and KB by SOS-inductive respomse were investigated using E. coli PQ37. Male rats were exposed to varying concentrations of MM, KB over a five week period to evaluate MM and KB phytoprotectives properties were also evaluated against sodium arsenite induced micronucleated erythrocytes, hepatotoxicity and sperm quality and morphology.

RESULTS

In contrast to KB, MM induced micronuclei formation in rat erythrocytes, MM and KB were however not genotoxic. MM, SA alone and in combination were hepatotoxic, characterized by elevated hepatic transaminases. Hepatoxicity were ameliorated by co-administration of KB (P < 0.05). MM and KB did not induce changes in semen morphology (P > 0.05); but decreased sperm count and motility (P < 0.05). Extracts exhibited anti-clastogenic (KB > MM), hepatoprotective (KB > MM) activities and maintained semen viability against SA treatment.

CONCLUSION

Finding applications as herbal medicinal and food components KB and MM may be useful in mitigating the effect of toxicants in biological systems susceptible to oxidative damage.

Inhibitory effects of sodium arsenite and acacia honey on acetylcholinesterase in rats

This study was conducted to investigate the effect of sodium arsenite and Acacia honey on acetylcholinesterase (AChE) activity and electrolytes in the brain and serum of Wistar rats. Male Wistar albino rats in four groups of five rats each were treated with distilled water, sodium arsenite (5 mg/kg body weight), Acacia honey (20% v/v), and sodium arsenite and Acacia honey, daily for one week. The sodium arsenite and Acacia honey significantly (P < 0.05) decreased AChE activity in the brain with the combined treatment being more potent. Furthermore, sodium arsenite and Acacia honey significantly (P < 0.05) decreased AChE activity in the serum. Strong correlation was observed between the sodium and calcium ion levels with acetylcholinesterase activity in the brain and serum. The gas chromatography mass spectrometry analysis of Acacia honey revealed the presence of a number of bioactive compounds such as phenolics, sugar derivatives, and fatty acids. These findings suggest that sodium arsenite and/or Acacia honey modulates acetylcholinesterase activities which may be explored in the management of Alzheimer's diseases but this might be counteracted by the hepatotoxicity induced by arsenics.

Protective effects of melatonin against arsenic-induced apoptosis and oxidative stress in rat testes

This study aimed to investigate the protective effects of melatonin against arsenic-induced apoptosis and oxidative stress in rat testes. A total of 27 male rats were divided into 3 groups: control (saline: 5 ml kg−1 day−1, intragastrically), arsenic (sodium arsenite (NaAsO2): 5 mg kg−1 day−1, intragastrically), and arsenic + melatonin (sodium arsenite (NaAsO2): 5 mg kg−1 day−1, intragastrically and melatonin: 25 mg kg−1 day−1, intraperitoneally) group. At the end of 30 days, the rats were killed under anesthesia. Histopathological examination showed that testicular injury mediated by arsenic was ameliorated by the administration of melatonin. The number of apoptotic germ cell was increased, and the number of proliferating cell nuclear antigen (PCNA)-positive germ cell was decreased in testis after arsenic administration. Our data indicate a significant reduction in the activity of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling, and there was a rise in the expression of PCNA in testis of arsenic + melatonin group. The decreased superoxide dismutase, catalase, and glutathione peroxidase activities as well as increased malondialdehyde levels in testis due to arsenic administration were also counteracted by melatonin. These data suggested that melatonin has beneficial effects against arsenic-induced testicular damage by decreasing morphological damage, germ cell apoptosis, lipid peroxidation, and oxidative stress. Our results suggest that melatonin plays a protective role against arsenic-induced testicular apoptosis and oxidative stress.

Ameliorative Effects of Acacia Honey against Sodium Arsenite-Induced Oxidative Stress in Some Viscera of Male Wistar Albino Rats

Cancer is a leading cause of death worldwide and its development is frequently associated with oxidative stress-induced by carcinogens such as arsenicals. Most foods are basically health-promoting or disease-preventing and a typical example of such type is honey. This study was undertaken to investigate the ameliorative effects of Acacia honey on sodium arsenite-induced oxidative stress in the heart, lung and kidney tissues of male Wistar rats. Male Wistar albino rats divided into four groups of five rats each were administered distilled water, Acacia honey (20%), sodium arsenite (5 mg/kg body weight), Acacia honey, and sodium arsenite daily for one week. They were sacrificed anesthetically using 60 mg/kg sodium pentothal. The tissues were used for the assessment of glutathione peroxidase, catalase, and superoxide dismutase activities, protein content and lipid peroxidation. Sodium arsenite significantly (P < 0.05) suppressed the glutathione peroxidase, catalase, superoxide dismutase activities with simultaneous induction of lipid peroxidation. Administration of Acacia honey significantly increased (P < 0.05) glutathione peroxidase, catalase, and superoxide dismutase activities with concomitant suppression of lipid peroxidation as evident by the decrease in malondialdehyde level. From the results obtained, Acacia honey mitigates sodium arsenite induced-oxidative stress in male Wistar albino rats, which suggest that it may attenuate oxidative stress implicated in chemical carcinogenesis.

Identification and characterization of metabolic properties of bacterial populations recovered from arsenic contaminated ground water of North East India (Assam)

Diversity of culturable bacterial populations within the Arsenic (As) contaminated groundwater of North Eastern state (Assam) of India is studied. From nine As contaminated samples 89 bacterial strains are isolated. 16S rRNA gene sequence analysis reveals predominance of Brevundimonas (35%) and Acidovorax (23%) along with Acinetobacter (10%), Pseudomonas (9%) and relatively less abundant (<5%) Undibacterium, Herbaspirillum, Rhodococcus, Staphylococcus, Bosea, Bacillus, Ralstonia, Caulobacter and Rhizobiales members. High As(III) resistance (MTC 10-50 mM) is observed for the isolates obtained from As(III) enrichment, particularly for 3 isolates of genus Brevundimonas (MTC 50 mM). In contrast, high resistance to As(V) (MTC as high as 550 mM) is present as a ubiquitous property, irrespective of isolates' enrichment condition. Bacterial genera affiliated to other groups showed relatively lower degree of As resistance [MTCs of 15-20 mM As(III) and 250-350 mM As(V)]. As(V) reductase activity is detected in strains with high As(V) as well as As(III) resistance. A strong correlation could be established among isolates capable of reductase activity and siderophore production as well as As(III) tolerance. A large number of isolates (nearly 50%) is capable of anaerobic respiration using alternate inorganic electron acceptors [As(V), Se(VI), Fe(III), [NO(3)(2), SO(4)(2), S(2)O(3)(2). Ability to utilize different carbon sources ranging from C2-C6 compounds along with some complex sugars is also observed. Particularly, a number of strains is found to possess ability to grow chemolithotrophically using As(III) as the electron donor. The study reports for the first time the identity and metabolic abilities of bacteria in As contaminated ground water of North East India, useful to elucidate the microbial role in influencing mobilization of As in the region.

An arsenic-contaminated field trial to assess the uptake and translocation of arsenic by genotypes of rice

Compared to other cereals, rice has particular strong As accumulation. Therefore, it is very important to understand As uptake and translocation among different genotypes. A field study in Chenzhou city, Hunan province of China, was employed to evaluate the effect of arsenic-contaminated soil on uptake and distribution in 34 genotypes of rice (including unpolished rice, husk, shoot, and root). The soil As concentrations ranged from 52.49 to 83.86 mg kg(-1), with mean As concentration 64.44 mg kg(-1). The mean As concentrations in rice plant tissues were different among the 34 rice genotypes. The highest As concentrations were accumulated in rice root (196.27-385.98 mg kg(-1) dry weight), while the lowest was in unpolished rice (0.31-0.52 mg kg(-1) dry weight). The distribution of As in rice tissue and paddy soil are as follows root ≫ soil > shoot > husk > unpolished rice. The ranges of concentrations of inorganic As in all of unpolished rice were from 0.26 to 0.52 mg kg(-1) dry weight. In particular, the percentage of inorganic As in the total As was more than 67 %, indicating that the inorganic As was the predominant species in unpolished rice. The daily dietary intakes of inorganic As in unpolished rice ranged from 0.10 to 0.21 mg for an adult, and from 0.075 to 0.15 mg for a child. Comparison with tolerable daily intakes established by FAO/WHO, inorganic As in most of unpolished rice samples exceeded the recommended intake values. The 34 genotypes of rice were classified into four clusters using a criteria value of rescaled distance between 5 and 10. Among the 34 genotypes, the genotypes II you 416 (II416) with the lowest enrichment of As and the lowest daily dietary intakes of inorganic As could be selected as the main cultivar in As-contaminated field.

Lipid peroxidation in brain tissue following administration of low and high doses of arsenite and L-ascorbate in wistar strain rats

This study aimed at investigating the mechanism by which sodium arsenite induces brain injury and the role of L-ascorbate. Thirty adult (n=5) Wistar rats weighing between 140 and 160 g were used. Group 1 neither received sodium arsenite nor L-ascorbate (control), group 2 was administered low dose of arsenite only, group 3 received high dose of arsenite only, group 4 was administered L-ascorbate only, group 5 was administered low dose of arsenite and L-ascorbate, and group 6 received high dose of arsenite and L-ascorbate. M0 alon dialdehyde, MDA, levels were significantly increased in rats treated with high dose of arsenite when compared with those treated with low dose of arsenite. However, all treated groups except those treated with L-ascorbate only showed significant increase in MDA levels when compared with the control group. Rats treated with high dose of arsenite and L-ascorbate showed a significantly higher MDA level than those treated with low dose of arsenite and L-ascorbate. However, catalase activity, body weight gain, brain weight and mean food consumption were comparable across all groups. Brain tissue total protein was similar in all groups except in both groups treated with high dose of arsenite, where they were significantly reduced when compared with the control group. I0 n conclusion, sodium arsenite treatment induces brain injury via a mechanism associated with lipid peroxidation, but not catalase-dependent. However, L-ascorbate ameliorates arsenite-induced oxidative injury in the brain. L-ascorbate antioxidative potential in alleviating arsenite-induced brain injury is dependent on the concentration of arsenite.

Translocation of arsenic contents in vegetables from growing media of contaminated areas

The aim of this study was to evaluate the translocation of arsenic (As) by different vegetables grown in agricultural soil irrigated for long period with tube well water as test vegetable samples and compared those vegetables of same species grown in agricultural soil irrigated with fresh canal water marked as control vegetable samples. Moreover, the total and ethylene-diamine-tetra acetic acid (EDTA) extractable contents of As in soil irrigated by tube well and canal water were determined and correlate with total concentrations of As in edible parts of vegetables. Statistically significant correlations were obtained between the total and EDTA extractable fractions of As in soil. High level of total and EDTA extractable As were found in tested vegetable samples as compared to controlled vegetable samples. This investigation highlights the increased danger of growing vegetables in the agricultural land continuously irrigated by As contaminated water.

Hematological, biochemical and ionoregulatory responses of Indian major carp Catla catla during chronic sublethal exposure to inorganic arsenic

In the present study the acute toxicity of arsenic trioxide in fingerlings of Catla catla an Indian major carp was evaluated with renewal bioassay method. The median lethal concentration of arsenic trioxide to the fish C. catla for 96 h was found to be 20.41 ppm (with 95% confidence limits). From this a non-lethal dose of (2.041 ppm; 1/10th of LC 50 96 value) was selected and fingerlings were exposed to 35 d and hematological, biochemical and ionoregulatory responses were studied at days 7, 14, 21, 28 and 35. Arsenic trioxide produced a significant increase in hemoglobin, hematocrit, WBC count, plasma GPT levels and reduction in RBC count, plasma sodium, chloride, potassium, glucose, protein, GOT, LDH levels as compared to the control group. Gill Na(+)/K(+)-ATPase activity was influenced by arsenic trioxide exposure. A biphasic response was noted in the value of MCH and MCV. However the MCHC level was not altered in arsenic trioxide treated fish throughout the study period. Results of the present investigation suggest that arsenic trioxide affects the hematological, biochemical and ionoregulatory parameters of fish and alterations of these parameters can be useful in environmental biomonitoring of arsenic contamination.

Evaluation of arsenic levels in grain crops samples, irrigated by tube well and canal water

The aim of this study was to evaluate the uptake of arsenic (As) by grain crops (wheat, maize and sorghum) grown on agricultural soil irrigated with tube well water (SIT) as test samples and for comparative purposes, same grain crop samples grown on agricultural soil irrigated with fresh canal water (SIC) were marked as control samples, collected simultaneously from three sub-districts of Khairpur, Pakistan. Moreover, this paper demonstrated the total and EDTA (0.05 M) extractable As in both understudied soils that correlate with the respective total As in the edible parts of the studied grain crops. A significantly high accumulation of As was found in grains grown on SIT as compared to those grown on SIC. This study highlights the increased danger of growing food crops in the agricultural land continuously irrigated by As contaminated ground water.

Arsenic contamination and potential health risk implications at an abandoned tungsten mine, southern China

In an extensive environmental study, field samples, including soil, water, rice, vegetable, fish, human hair and urine, were collected at an abandoned tungsten mine in Shantou City, southern China. Results showed that arsenic (As) concentration in agricultural soils ranged from 3.5 to 935 mg kg(-1) with the mean value of 129 mg kg(-1). In addition, As concentration reached up to 325 microg L(-1) in the groundwater, and the maximum As concentration in local food were 1.09, 2.38 and 0.60 mg kg(-1) for brown rice, vegetable and fish samples, respectively, suggesting the local water resource and food have been severely contaminated with As. Health impact monitoring data revealed that As concentrations in hair and urine samples were up to 2.92 mg kg(-1) and 164 microg L(-1), respectively, indicating a potential health risk among the local residents. Effective measurements should be implemented to protect the local community from the As contamination in the environment.

Arsenic burden from cooked rice in the populations of arsenic affected and nonaffected areas and Kolkata City in West-Bengal, India

Arsenic contamination of rice irrigated with contaminated groundwater contributes to the additional arsenic burden of the population where rice is the staple food. In an arsenic contaminated area, an experimental field-based study done on nine fields elucidated significant positive correlation between arsenic in irrigation water and soil, irrigation water and rice, and also soil and rice both for Boro (groundwater) and Aman (rainwater) rice. Speciation studies showed that for both Boro (cooked) and Aman (raw) rice from contaminated area, 90% of total recovered arsenic was inorganic. In arsenic contaminated, uncontaminated villages, and Kolkata city, daily quantities of arsenic ingested by adult population from cooked rice diet are equivalent to 6.5, 1.8, and 2.3 L respectively, of drinking water containing WHO guideline value. In contaminated area, daily intake only from cooked Boro rice for 34.6% of the samples exceeded the WHO recommended MTDI value (2 microg In-As day(-1) kg(-1) body wt), whereas daily intake from Aman rice was below MTDI value as was rice from uncontaminated areas and Kolkata city. Our study indicated that employing traditional rice cooking method as followed in Bengal delta and using water having arsenic <3 microg L(-1) for cooking, actual exposure to arsenic from rice would be much less.

Warming and drought change trace element bioaccumulation patterns in a Mediterranean shrubland

A field experiment consisting of drought and warming manipulation was conducted in a Mediterranean shrubland dominated by the shrubs Erica multiflora and Globularia alypum. The aim was to investigate the effects of the climatic changes predicted by IPCC models for the coming decades on trace element concentration and accumulation in aboveground biomass, plant litter, and soil. Warming increased concentrations and aboveground accumulation of some trace elements related to plant root uptake, such as Al, As, Cr, Cu, and partially Pb. This effect was more general in E. multiflora than in G. alypum. The stronger effects were increases in Al leaf concentrations (42%) and aboveground accumulation (500gha(-1)) in E. multiflora, in As stem biomass accumulation (0.2gha(-1)) in E. multiflora, and in Cr leaf concentrations (51%) in G. alypum and stem aboveground accumulation in E. multiflora (1.1gha(-1)). These species-specific increases were related to greater retranslocation, photosynthetic capacity and growth in E. multiflora than in G. alypum. Warming decreased the concentrations of some trace elements in leaf litter, implying the existence of an increased leaf retranslocation. Drought increased As (40%) and Cd (55%) in E. multiflora stems, whereas it decreased Cu (50%) in leaves, Ni (28%) in stems and Pb (32%) in leaf litter of G. alypum. The increasing concentrations of some trace elements in E. multiflora and not in G. alypum were related to a greater growth reduction in E. multiflora than in G. alypum. Warming increased As soil solubility (67%) and decreased total soil As (21%). Those changes were related to a greater Fe mobilization in warming plot and to a greater plant capture. Drought increased Hg (350%) concentrations in soils but had no significant effects on trace element accumulation in aboveground biomass. The different response to warming and drought in the two dominant species implies uneven changes in the quality of the plant tissues that may have implications for herbivores. This may be specially important for the performance of the studied Mediterranean ecosystems under the warmer and drier conditions predicted by the next decades by the GCM and ecophysiological models.

Detection of arsenic in water, herbal and soil samples by neutron activation analysis technique

Arsenic contamination of ground water is well understood while other environmental systems are rarely considered to be contaminated by arsenic. A vital issue is whether or not appreciable arsenic transmits through the food chain. Reportedly, ayurvedic herbal medicine products (AHMPs) manufactured in Asia were found to be contaminated by harmful level of Arsenic. This study was aimed to quantify the arsenic levels in water, herbal and soil samples collected from the same origin using highly accurate neutron activation analysis (NAA) technique. Harmful level of arsenic was detected in most of the water and soil samples. Moreover, a considerably harmful level of Arsenic was detected in herbal samples collected from the same origin. As a result, AHMPs manufactured in Asia might be contaminated by arsenic through arsenic contaminated herb plants.

Drought changes the dynamics of trace element accumulation in a Mediterranean Quercus ilex forest

We conducted a field drought manipulation experiment in an evergreen oak Mediterranean forest from 1999 to 2005 to investigate the effects of the increased drought predicted for the next decades on the accumulation of trace elements that can be toxic for animals, in stand biomass, litter and soil. Drought increased concentrations of As, Cd, Ni, Pb and Cr in roots of the dominant tree species, Quercus ilex, and leaf Cd concentrations in Arbutus unedo and of Phillyrea latifolia codominant shrubs. The increased concentration of As and Cd can aggravate the toxic capacity of those two elements, which are already next or within the levels that have been shown to be toxic for herbivores. The study also showed a great reduction in Pb biomass content (100-135 gha(-1)) during the studied period (1999-2005) showing the effectiveness of the law that prohibited leaded fuel after 2001. The results also indicate that drought increases the exportation of some trace elements to continental waters.

Daily intakes of copper, zinc and arsenic in drinking water by population of Shanghai, China

Daily intakes of metals in drinking water are of extreme importance in risk assessment to human health. Some papers focused on this topic, but most of them did not consider the effect of age, gender and work location on daily intakes of metals in drinking water. The objective of present paper is to estimate the levels of Cu, Zn and As ingestion in drinking water in Shanghai, China and the effect of age, gender and work location on daily intakes of these metals. It was also the first time that such a detailed investigation on daily intakes of metals in drinking water was carried out in China in recent years. Drink/Sample (D/S) method was used to estimate the daily intakes of Cu, Zn and As in drinking water. The mean concentrations of Cu, Zn and As in drinking water were 10.8 microg/l, 0.29 mg/l and 0.91 microg/l, which were lower than U.S. EPA's Drinking Water Equivalent Level (DWEL) and WHO guideline values. The average daily intakes of Cu, Zn and As in drinking water was 21.12 microg/d, 0.65 mg/d, and 1.83 microg/d, which were on average 0.01%, 1.1% and 1.5% of the provisional maximum tolerable daily intake (PMTDI) set by the Joint FAO/WHO Expert Committee. There was a significant difference in daily intake of Zn for different work locations (P=0.04). But no other significant differences in daily intakes of metals in drinking water were found according to age, gender and work location.

Soil As contamination and its risk assessment in areas near the industrial districts of Chenzhou City, Southern China

In order to assess soil As contamination and potential risk for human, soil, paddy rice, vegetable and human hair samples from the areas near the industrial districts in Chenzhou, southern China were sampled and analyzed. The results showed that the anthropogenic industrial activities have caused in local agricultural soils to be contaminated with As in a range of 11.0-1217 mg/kg. The GIS-based map shows that soil contamination with As occurred on a large scale, which probably accounted for up to 30% of the total area investigated. Soil As concentration abruptly decreased with an increase in the distance from the polluting source. High As concentrations were found in the rice grain that ranged from 0.5 to 7.5 mg/kg, most of which exceed the maximal permissible limit of 1.0 mg/kg dry matter. Arsenic accumulated in significantly different levels between leafy vegetables and non-leafy vegetables. Non-leafy vegetables should be recommended in As-contaminated soils, as their edible parts were found in relatively low As level. Arsenic concentrations in 95% of the total human hair samples in the contaminated districts were above the critical value, 1.0 mg/kg, set by the World Health Organization. Arsenic could be enriched in human hair to very high levels without being affected by As containing water. The results revealed that the soils and plants grown on them are major contributors to elevate hair As in the industrial population. Therefore, the potential impact on human health of ingestion/inhalation of soil As around the industrial districts seems to be rather serious. Hence proper treatments for As contaminated soils are urgently needed to reduce the contamination.

Effect of arsenic-contaminated irrigation water on agricultural land soil and plants in West Bengal, India

Total arsenic withdrawn by the four shallow tubewells, used for agricultural irrigation in the arsenic-affected areas of Murshidabad district per year is 6.79 kg (mean: 1.79 kg, range: 0.56-3.53 kg) and the mean arsenic deposition on land per year is 5.02 kg ha(-1) (range: 2-9.81 kg ha(-1)). Mean soil arsenic concentrations in surface, root of plants, below ground level (0-30 cm) and all the soils, collected from four agricultural lands are 14.2 mg/kg (range: 9.5-19.4 mg/kg, n = 99), 13.7 mg/kg (range: 7.56-20.7 mg/kg, n = 99), 14.8 mg/kg (range: 8.69-21 mg/kg, n = 102) and 14.2 mg/kg (range: 7.56-21 mg/kg, n = 300) respectively. Higher the arsenic in groundwater, higher the arsenic in agricultural land soil and plants has been observed. Mean arsenic concentrations in root, stem, leaf and all parts of plants are 996 ng/g (range: <0.04-4850 ng/g, n = 99), 297 ng/g (range: <0.04-2900 ng/g, n = 99), 246 ng/g (range: <0.04-1600 ng/g, n = 99) and 513 ng/g (range: <0.04-4850 ng/g, n = 297) respectively. Approximately 3.1-13.1, 0.54-4.08 and 0.36-3.45% of arsenic is taken up by the root, stem and leaf respectively, from the soil.

Survey of arsenic and other heavy metals in food composites and drinking water and estimation of dietary intake by the villagers from an arsenic-affected area of West Bengal, India

An investigation of arsenic, copper, nickel, manganese, zinc and selenium concentration in foodstuffs and drinking water, collected from 34 families and estimation of the average daily dietary intake were carried out in the arsenic-affected areas of the Jalangi and Domkal blocks, Murshidabad district, West Bengal where arsenic-contaminated groundwater (mean: 0.11 mg/l, n=34) is the main source for drinking. The shallow large diameter tubewells, installed for agricultural irrigation contain an appreciable amount of arsenic (mean: 0.094 mg/l, n=10). So some arsenic can be expected in the food chain and food cultivated in this area. Most of the individual food composites contain a considerable amount of arsenic. The mean arsenic levels in food categories are vegetables (20.9 and 21.2 microg/kg), cereals and bakery goods (130 and 179 microg/kg) and spices (133 and 202 microg/kg) for the Jalangi and Domkal blocks, respectively. For all other heavy metals, the observed mean concentration values are mostly in good agreement with the reported values around the world (except higher zinc in cereals). The provisional tolerable daily intake value of inorganic arsenic microg/kg body wt./day) is: for adult males (11.8 and 9.4); adult females (13.9 and 11); and children (15.3 and 12) in the Jalangi and Domkal blocks, respectively (according to FAO/WHO report, the value is 2.1 microg/kg body wt./day). According to WHO, intake of 1.0 mg of inorganic arsenic per day may give rise to skin lesions within a few years. The average daily dietary intake of copper, nickel and manganese is high, whereas for zinc, the value is low (for adult males: 8.34 and 10.2 mg/day; adult females: 8.26 and 10.3 mg/day; and children: 4.59 and 5.66 mg/day) in the Jalangi and Domkal blocks, respectively, compared to the recommended dietary allowance of zinc for adult males, adult females and children (15, 12 and 10 mg/day, respectively). The average daily dietary intake of selenium microg/kg body wt./day) is on the lower side for the children (1.07 and 1.22), comparable for the adult males (0.81 and 0.95) and slightly on the higher side for the adult females (1.08 and 1.26), compared to the recommended value (1.7 and 0.9 microg/kg body wt./day for infants and adults, respectively).

Arsenic and other heavy metals in soils from an arsenic-affected area of West Bengal, India

Domkal is one of the 19, out of 26 blocks in Murshidabad district where groundwater contains arsenic above 0.05 mg/l. Many millions of cubic meters of groundwater along with arsenic and other heavy metals are coming out from both the hand tubewells, used by the villagers for their daily needs and shallow big diameter tubewells, installed for agricultural irrigation and depositing on soil throughout the year. So there is a possibility of soil contamination which can moreover affect the food chain, cultivated in this area. A somewhat detailed study was carried out, in both micro- and macrolevel, to get an idea about the magnitude of soil contamination in this area. The mean concentrations (mg/kg) of As (5.31), Fe (6740), Cu (18.3), Pb (10.4), Ni (18.8), Mn (342), Zn (44.3), Se (0.53), Mg (534), V (44.6), Cr (33.1), Cd (0.37), Sb (0.29) and Hg (0.54) in fallow land soils are within the normal range. The mean As (10.7), Fe (7860) and Mg (733) concentrations (mg/kg) are only in higher side whereas Hg (0.17 mg/kg) is in lower side in agricultural land soils, compared to the fallow land soils. Arsenic concentrations (11.5 and 28.0 mg/kg respectively) are high in those agricultural land soils where irrigated groundwater contains high arsenic (0.082 and 0.17 mg/l respectively). The total arsenic withdrawn and mean arsenic deposition per land by the 19 shallow tubewells per year are 43.9 kg (mean: 2.31 kg, range: 0.53-5.88 kg) and 8.04 kg ha(-1) (range: 1.66-16.8 kg ha(-1)) respectively. For the macrolevel study, soil arsenic concentration decreases with increase of distance from the source and higher the water arsenic concentration, higher the soil arsenic at any distance. A proper watershed management is urgently required to save the contamination.

Survey of arsenic in food composites from an arsenic-affected area of West Bengal, India

An investigation of total arsenic in food composites, collected from the villagers, was carried out in arsenic-affected areas of the Murshidabad district, West Bengal where the agricultural system is mostly groundwater dependent. The shallow, large-diameter tubewells installed for agricultural irrigation contain an appreciable amount of arsenic (mean 0.085 mg/l, n=6). Even the soil is arsenic-contaminated (mean 11.35 mg/kg, n=36), so some arsenic can be expected in the food chain from crops cultivated in this area. The results revealed that the individual food composite and food groups containing the highest mean arsenic concentrations (microg/kg) are potato skin (292.62 and 104), leaf of vegetables (212.34 and 294.67), arum leaf (331 and 341), papaya (196.50 and 373), rice (226.18 and 245.39), wheat (7 and 362), cumin (47.86 and 209.75), turmeric powder (297.33 and 280.9), cereals and bakery goods (156.37 and 294.47), vegetables (91.73 and 123.22), spices (92.22 and 207.60) and miscellaneous items (138.37 and 137.80) for the Jalangi and Domkal blocks, respectively. Arsenic is absorbed by the skin of most of the vegetables. The arsenic concentration in fleshy vegetable material is low (mean 2.72 microg/kg, n=45). Higher levels of arsenic were observed in cooked items compared with raw. Daily dietary intakes of arsenic (microg) from the foodstuffs for adults are 171.20 and 189.13 and for children are 91.89 and 101.63 in the Jalangi and Domkal blocks, respectively.

Arsenic, Sb and Bi contamination of soils, plants, waters and sediments in the vicinity of the Dalsung Cu-W mine in Korea

The objective of this study is to investigate environmental contamination derived from metalliferous mining activities. In the study area, the Dalsung Cu-W mine, soils, various crop plants, stream waters, sediments and particulates were sampled in and around the mine and analyzed for As, Sb and Bi by ICP-AES with a hydride generator. In addition, soil pH, cation exchange capacity, loss-on-ignition and soil texture were also measured. Concentrations of As, Sb and Bi in surface soils sampled in the mine dump sites averaged 2500, 54 and 436 microg g(-1), respectively. Relatively lower concentrations, however, were found in soils from alluvial and high land sites and household garden sites. Arsenic, Sb and Bi contents in plant samples varied depending upon their species and parts, with higher concentrations in spring onions, soybean leaves and perilla leaves and lower levels in red peppers, corn grains and jujube grains. These results confirm that elemental concentrations in plant leaves are much higher than those in plant grain. Elevated levels of As, Sb and Bi were also found in stream sediments sampled in the vicinity of the mine and decreased with distance from the mine. Concentrations in stream water samples ranged from 0.8 to 19.1 microg As l(-1) and from 0.3 to 8.4 microg Bi l(-1); all the samples contained less than 1.0 microg Sb l(-1). Because of very low particulate loading at the time of sampling, the metal contents in particulates were very low (< 8.2 microg As l(-1), < 0.22 microg Sb l(-1) and 2.8 microg Bi l(-1). This may be mainly due to the low solubility of those elements under moderately acidic and oxidizing conditions of the mining area.

Determination of lead and other metals in a residential area of greater Calcutta

The aim of the study was to determine the major source and extent of metal pollution in a residential area of Greater Calcutta. In this area approximately 50,000 people reside in the vicinity of a lead factory that produces lead ingots and lead alloys. Many people, especially children, are affected by lead toxicity. Soils, waters, road dust, leaf dust, leaves and pond sediments were sampled in and around the factory area. Aliquots of the samples were mineralized with nitric acid and hydrogen peroxide in a microwave system. Lead and 19 other elements were quantified in the digests by inductively coupled plasma mass spectrometry. The performance of the procedure was confirmed by analyzing NBS-BCR standard reference soil, leaves, sediment samples. The soils are highly contaminated not only with lead (4.7%), but also with Cd (0.08%), Ag (0.001%), Cu (0.02%), Zn (1.0%), As (1.0%), Mo (0.003%), Sn (0.003%) and Hg (0.03%) (metal concentrations given in parentheses are maximum). Moving away from the smelter, most of metal concentrations, especially Pb, As, Mo, Cu, Hg, Zn, Cd, Sn and Ag, decreased exponentially over increasing distance. In the residential areas near the smelter, notably to the west side of the factory, metal concentrations significantly breached the threshold trigger values set in India by the Central Pollution Control Board (CPCB). Particulate materials from the smelter stack appear to contaminate soils up to at least 0.5 km. However, abnormally high metal levels in the immediate smelter area may be due to primarily fugitive emissions. The surface waters are only contaminated by arsenic ranges from 0.05 to 13.5 mg/l, but the ground water is currently not polluted by lead and arsenic. An appropriate treatment plant with some intervention measures should be taken to save the locality.

Impact of safe water for drinking and cooking on five arsenic-affected families for 2 years in West Bengal, India

The groundwater in seven districts of West Bengal, India, covering an area of 37,000 km2 with a population of 34 million, has been contaminated with arsenic. In 830 villages/wards more than 1.5 million people, out of the total population, drink the arsenic-contaminated water. Safe water from a source having < 0.002 mg 1(-1) arsenic has been supplied for 2 years to five affected families comprising 17 members (eight of them with arsenical skin-lesions) of different age groups for impact assessment study in terms of loss of arsenic through urine, hair and nail. The study indicates random observable fluctuations of arsenic concentration in urine among members on different scheduled sampling days with a declining trend, particularly during the first 6 months. Furthermore, the investigation showed that despite having safe water for drinking and cooking, the study group could not avoid an intake of arsenic, time and again, through edible herbs grown in contaminated water, food materials contaminated through washing, and the occasional drinking of contaminated water. After minimizing the level of contamination, a noteworthy declining trend after 8 months was observed in urine, hair and nails in all the cases, but not to that level observed in a normal population, due to prevailing elevated background level of arsenic in the area. The eight members, who had already developed skin lesions, are far from recovering completely, indicating a long-lasting damage. Statistical interpretation of the data are considered.

Arsenic in groundwater in six districts of West Bengal, India

Arsenic in groundwater above the WHO maximum permissible limit of 0.05 mg l(-1) has been found in six districts of West Bengal covering an area of 34 000 km(2) with a population of 30 million. At present, 37 administrative blocks by the side of the River Ganga and adjoining areas are affected. Areas affected by arsenic contamination in groundwater are all located in the upper delta plain, and are mostly in the abandoned meander belt. More than 800 000 people from 312 villages/wards are drinking arsenic contaminated water and amongst them at least 175 000 people show arsenical skin lesions. Thousands of tube-well water in these six districts have been analysed for arsenic species. Hair, nails, scales, urine, liver tissue analyses show elevated concentrations of arsenic in people drinking arsenic-contaminated water for a longer period. The source of the arsenic is geological. Bore-hole sediment analyses show high arsenic concentrations in only few soil layers which is found to be associated with iron-pyrites. Various social problems arise due to arsenical skin lesions in these districts. Malnutrition, poor socio-economic conditions, illiteracy, food habits and intake of arsenic-contaminated water for many years have aggravated the arsenic toxicity. In all these districts, major water demands are met from groundwater and the geochemical reaction, caused by high withdrawal of water may be the cause of arsenic leaching from the source. If alternative water resources are not utilised, a good percentage of the 30 million people of these six districts may suffer from arsenic toxicity in the near future.