Effects of organic matter and ageing on the bioaccessibility of arsenic

• Published in: Environmental pollution (1987) 2011-10, Vol.159 (10), p.2530-2536
• Main Authors: Meunier, Louise, Koch, Iris, Reimer, Kenneth J.
• Format: Article
• Language: English
• Subjects: Age; Air. Soil. Water. Waste. Feeding; Applied sciences; Arsenic; Arsenic - chemistry; Bioaccessibility; Biological and medical sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environment. Living conditions; Exact sciences and technology; Medical sciences; Mining; Organic matter; Other industrial wastes. Sewage sludge; Oxidation-Reduction; Pollution; Pollution, environment geology; Public health. Hygiene; Public health. Hygiene-occupational medicine; Soil - chemistry; Soil and sediments pollution; Soil Pollutants - chemistry; Sphagnopsida - chemistry; Tailings; Wastes; Weather; Weathering
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2011.06.018

Arsenic-contaminated soils may pose a risk to human health. Redevelopment of contaminated sites may involve amending soils with organic matter, which potentially increases arsenic bioaccessibility. The effects of ageing on arsenic-contaminated soils mixed with peat moss were evaluated in a simulated ageing period representing two years, during which arsenic bioaccessibility was periodically measured. Significant increases (p = 0.032) in bioaccessibility were observed for 15 of 31 samples tested, particularly in comparison with samples originally containing >30% bioaccessible arsenic in soils naturally rich in organic matter (>25%). Samples where percent arsenic bioaccessibility was unchanged with age were generally poor in organic matter (average 7.7%) and contained both arsenopyrite and pentavalent arsenic forms that remained unaffected by the organic matter amendments. Results suggest that the addition of organic matter may lead to increases in arsenic bioaccessibility, which warrants caution in the evaluation of risks associated with redevelopment of arsenic-contaminated land. ► Adding organic matter to contaminated soils may increase arsenic bioaccessibility. ► Ageing soils with >25% organic matter can lead to increased arsenic bioaccessibility. ► No changes in arsenic bioaccessibility for soils poor in organic matter (mean 7.7%). ► No changes in arsenic bioaccessibility for samples containing arsenopyrite. ► Organic matter in soil may favour oxidation of trivalent arsenic to pentavalent form. Adding organic carbon may increase arsenic bioaccessibility, especially in samples originally containing >30% bioaccessible arsenic in organic carbon-rich soils (>25%).