Arsenic Pathways Research Articles

Arsenic Pathways in the Environment: The Role of Contaminated Groundwater in the Dispersion of Arsenic to Soil, Vegetables and Chicken Meat

Arsenic Pathways in the Environment: The Role of Contaminated Groundwater in the Dispersion of Arsenic to Soil, Vegetables and Chicken Meat

Seven potential sources of arsenic pollution in Latin America and their environmental and health impacts.

This review presents a holistic overview of the occurrence, mobilization, and pathways of arsenic (As) from predominantly geogenic sources into different near-surface environmental compartments, together with the respective reported or potential impacts on human health in Latin America. The main sources and pathways of As pollution in this region include: (i) volcanism and geothermalism: (a) volcanic rocks, fluids (e.g., gases) and ash, including large-scale transport of the latter through different mechanisms, (b) geothermal fluids and their exploitation; (ii) natural lixiviation and accelerated mobilization from (mostly sulfidic) metal ore deposits by mining and related activities; (iii) coal deposits and their exploitation; (iv) hydrocarbon reservoirs and co-produced water during exploitation; (v) solute and sediment transport through rivers to the sea; (vi) atmospheric As (dust and aerosol); and (vii) As exposure through geophagy and involuntary ingestion. The two most important and well-recognized sources and mechanisms for As release into the Latin American population's environments are: (i) volcanism and geothermalism, and (ii) strongly accelerated As release from geogenic sources by mining and related activities. Several new analyses from As-endemic areas of Latin America emphasize that As-related mortality and morbidity continue to rise even after decadal efforts towards lowering As exposure. Several public health regulatory institutions have classified As and its compounds as carcinogenic chemicals, as As uptake can affect several organ systems, viz. dermal, gastrointestinal, peptic, neurological, respiratory, reproductive, following exposure. Accordingly, ingesting large amounts of As can damage the stomach, kidneys, liver, heart, and nervous system; and, in severe cases, may cause death. Moreover, breathing air with high As levels can cause lung damage, shortness of breath, chest pain, and cough. Further, As compounds, being corrosive, can also cause skin lesions or damage eyes, and long-term exposure to As can lead to cancer development in several organs.

Pathways of arsenic from sediments to groundwater in the hyporheic zone: Evidence from an iron isotope study

Summary Ssulfide, Fe content and heavy Fe isotopic signatures of the bulk core sediments all indicate anoxic and sulfidic conditions in the hyporheic zone. The relationship between Ssulfide and Fe contents suggests that Fe(III) oxides/hydroxides are transferred between non-sulfidic Fe(II) minerals and Fe(II)-sulfides under anoxic and sulfidic conditions, respectively. The Fe isotope composition provides further evidence that microbial dissimilatory reduction of Fe(III) and the formation of Fe(II)-sulfides and non-sulfidic Fe(II) minerals are the dominant Fe geochemical pathways and take place at different depths in the hyporheic zone. In the upper sections of the Core A and B (with depth less than ≈10 m), microbial Fe(III) reduction and non-sulfidic Fe(II) minerals formation govern the Fe cycling and the Fe isotope composition in hyporheic water and bulk sediments. Microbial Fe(III) and SO 4 2 - reduction and interaction between produced Fe(II)aq and Fe(II)-sulfides precipitate control δ56Fe values of sediments and water sample in the midsections (≈13–19 m) of the Core A. Conversely, abiotic Fe(III) reduction by HS− determines the bulk δ56Fe values of core sediments and water in the midsections (≈13–19 m) of the Core B. Microbial SO 4 2 - reduction is limited and microbial Fe(III) reduction controls the δ56Fe values of water and sediments at the bottom of both cores. The variation of δ56Fe values and the As concentration in hyporheic water are similar at each depth, indicating that As enrichment in the water is strongly associated with the microbial reduction of Fe(III) oxides/hydroxides and the formation of Fe(II)-sulfides and non-sulfidic Fe(II) minerals. The enriched-δ56Fe values of high As water concentrations suggest that microbial reduction of Fe(III) oxides/hydroxides is the dominant process that promotes As mobility in the hyporheic zones.

Arsenic Pathways in Self-Catalyzed Growth of GaAs Nanowires

Self-catalyzed growth of GaAs nanowires by molecular beam epitaxy on (111)Si substrates is investigated by introducing AlxGa1–xAs time markers. The nanowire elongation rate is found to be radius-independent, constant at substrate temperatures below 650 °C and linearly increasing with the incoming arsenic flux. The basic question of which pathways are followed by the arsenic species contributing to nanowire growth is clarified. The flow rate of As atoms directly impinging on the Ga catalyst drop is significantly smaller than the As consumption by nanowire growth. Thus, supplementary As atoms are necessary to explain the actual elongation rate. We show that surface diffusion of adsorbed Asx species toward the catalyst cannot account for the missing atoms. On the other hand, the reevaporation of Asx species from the substrate and from nanowire sidewall surfaces can act as an efficient secondary arsenic source. We argue that a sufficient amount of these species can be intercepted by the Ga drop and add up with the direct As impingement to explain the actual elongation rate.

Local Market Research on Vegetable in Jessore of the High Ganges River Floodplain, Bangladesh

INTRODUCTIONMarket is a most active site in daily life of people in monsoon Asian countries. Vegetables in a market are mostly local products in Bangladesh. While, fruits are frequently imported from other areas or countries. We have visited Jessore District, located in the southwestern part of Bangladesh, in the field survey of Kyushu University P&P Project (Kyushu University Interdisciplinary Programs in Education and Projects in Research Development) of “An empirical study on the pathway of arsenic from groundwater contamination to human health hazard” headed by Dr. Masakazu Tani, Associated Professor of the Faculty of Design, Kyushu University.Jessore District occupies a southern half of the High Ganges River Floodplain, and the land is calcareous and mostly above normal flood–level (FAO–UNDP, 1988). Vegetables and pulses are cultivated in the filed as crops in the cropping patterns under rainfed and irrigated con-ditions (Bangladesh Agricultural Research Council, 2005). We have observed vegetables grown in the field and in the garden around farmer’s houses. In the present study, market research on vegetables was done in July 2006 and March and July 2007 at a vegetable bazaar in Jessore Town and in March and July at a hut in Marua Village of Chowgaccha Upazila. March is in the late dry season and July is in the early rainy season in Bangladesh. The purpose of the present study is to identify vegetables sold at bazaar and hut and to under-stand seasonal variation in the kind and price of vegeta-bles in Jessore, Bangladesh.MATERIALS AND MRTHODS

Arsenic: exposure and health effects

The value of research on health effects of ingested inorganic arsenic. Human oral exposure to inorganic arsenic. Nationwide and California arsenic occurrence studies. Dietary intake and hazards of arsenic. Determination of total arsenic and arsenic compounds in drinking water. Sources and pathways of arsenic in Southwest England: health implications. Exposure assessment for arsenic concentrations from electric power stations. Ischemic heart disease induced by ingested inorganic arsenic. Urinary excretion of arsenic species in a human population chronically exposed to arsenic via drinking water: a pilot study. Long-term follow-up of patients treated with medicinal arsenic. Epidemiological study designs to address potential high bladder cancer risks from arsenic in drinking water. Arsenic in drinking water and urinary cancers. Arsenic in drinking water and cancers: a brief descriptive review of Taiwan studies. Review of health assessments for US/Canada populations exposed to arsenic in drinking water. Assessment of the dose response for internal cancers and arsenic in drinking water in the blackfoot disease endemic region of Taiwan. Species differences in the metabolism of arsenic. Inorganic arsenic metabolism in humans. Genotoxicity of arsenic and its methylated metabolites. Arsenic essentiality studies and factors affecting its importance. A physiologically based pharmacokinetic model for ingested arsenic. Overview of a physiologically based pharmacokinetic model for the four major arsenic species in mammals. Water utility regulatory and research projects on arsenic. The use of site-specific studies to assess arsenic health risk at superfund site. The process for setting drinking water regulations under the Safe Drinking Water Act. Arsenic in the Canadian general environment: evaluation of risks to health. Impacts of a stringent arsenic drinking water regulation on the western USA. Arsenic in drinking water: health effects and regulatory issues in California. Regulating arsenic in Nevada drinking water supplies: past problems, future challenges. The water utility perspective on arsenic regulation. Derivation of the inorganic arsenic reference dose. Arsenic and human health: some persisting scientific issues.

Sources and pathways of arsenic in the geochemical environment: health implications

Abstract Arsenic is ubiquitous in the environment, being present in small amounts in all rock, soil, dust, water and air. It is associated with many types of mineral deposits and in particular those containing sulphide minerals. The most common arsenic mineral is arsenopyrite, FeAsS 2 . Elevated concentrations are sometimes found in fine grained argillaceous sediments and phosphorites. Some marine sediments may contain as much as 3000 mg kg −1 . Arsenic is co-precipitated with iron hydroxides and sulphides in some sedimentary rocks, and is precipitated as ferric arsenate in soil horizons rich in iron. This paper reviews current knowledge on the natural geochemical sources of arsenic in several countries where high concentrations in soils, dusts, surface and groundwaters may present a hazard to human health. The chemistry and behaviour of arsenic within the weathering zone are discussed in relation to pathways leading to human exposure.