Arsenic Contamination of Groundwater and Drinking Water in Vietnam:  A Human Health Threat

Abstract

This is the first publication on arsenic contamination of the Red River alluvial tract in the city of Hanoi and in the surrounding rural districts. Due to naturally occurring organic matter in the sediments, the groundwaters are anoxic and rich in iron. With an average arsenic concentration of 159 micrograms/L, the contamination levels varied from 1 to 3050 micrograms/L in rural groundwater samples from private small-scale tubewells. In a highly affected rural area, the groundwater used directly as drinking water had an average concentration of 430 micrograms/L. Analysis of raw groundwater pumped from the lower aquifer for the Hanoi water supply yielded arsenic levels of 240-320 micrograms/L in three of eight treatment plants and 37-82 micrograms/L in another five plants. Aeration and sand filtration that are applied in the treatment plants for iron removal lowered the arsenic concentrations to levels of 25-91 micrograms/L, but 50% remained above the Vietnamese Standard of 50 micrograms/L. Extracts of sediment samples from five bore cores showed a correlation of arsenic and iron contents (r2 = 0.700, n = 64). The arsenic in the sediments may be associated with iron oxyhydroxides and released to the groundwater by reductive dissolution of iron. Oxidation of sulfide phases could also release arsenic to the groundwater, but sulfur concentrations in sediments were below 1 mg/g. The high arsenic concentrations found in the tubewells (48% above 50 micrograms/L and 20% above 150 micrograms/L) indicate that several million people consuming untreated groundwater might be at a considerable risk of chronic arsenic poisoning.

Arsenic Levels and Speciation from Ingestion Exposures to Biomarkers in Shanxi, China: Implications for Human Health

“…However, we cannot wait for the development of arsenicosis to make any mitigation efforts because the As chronic toxicity symptoms are indeed time-lag effects. 1,36 ■ ASSOCIATED CONTENT * S Supporting Information Details of sample collection; microwave digestion of soils, vegetables, cereals, nails, and hair samples; As speciation using HPLC-AFS; statistical methods; μ-XRF and μ-XANES sample preparation and analysis; and additional figures and tables. This material is available free of charge via the Internet at http:// pubs.acs.org.…”

Temporal variability of groundwater chemistry in shallow and deep aquifers of Araihazar, Bangladesh

“…Large seasonal variations of groundwater As levels were also reported in 5 monitoring wells at depths of 3-60 m in Samta village of Western Bangladesh (AAN, 1999), although the measurements of As were few and made by a less reliable method (silver dithiodicarbomate spectrometry) in a local laboratory. There is more convincing evidence that As concentration declined between SeptemberDecember, 1999, and May 2000 in many of the 68 wells sampled twice in four districts of the Red River delta (Berg et al, 2001). Naturally occurring As in groundwater of Granite Falls, Washington, ranging in concentration from <10 µg/L to 14,000 µg/L also showed substantial temporal variability of 12-79% for 15 out of 25 private drinking water wells monitored over 12 months (Frost et al, 1993).…”

Arsenic accumulation by the aquatic fern Azolla: Comparison of arsenate uptake, speciation and efflux by A. caroliniana and A. filiculoides

“…In particular, As contamination in groundwater has become a crucial environmental and health problem in some parts of the world, especially in Bangladesh, Vietnam, India and China (Berg et al, 2001;Smith et al, 2000;Milton et al, 2005). The WHO guideline for As in drinking water has been changed from 50 to 10 mg/L (Smith et al, 2002;Mohan and Charles, 2007).…”