Arsenic and its bioavailability in surface waters in a black schist area in northern Sweden

• The Västerbotten county in northern Sweden is largely underlain by Precambrian bedrock. There are numerous sulfide ore bodies and gold deposits accompanied by arsenic. However, more black schists with a sulfur content of about 1% are a more widespread source of arsenic (As). The arsenic is accumulated in the B-horizon of tills but also remobilized in wetlands and released into surface water. Sandy sediments in brooks and streams may contain up to 500 mg/kg As adsorbed onto ferric (Fe) oxyhydroxides. Lakes may contain up to 19 ÎŒg/LAs. Speciation of As has been investigated in lake water by filtration and dialysis. Four lakes have been investigated varying from a clear-water lake to lakes high in Fe and DOC (dissolved organic carbon). The As is closely correlated to Fe in the different fractions. The fraction < 1 kDa is low in As indicating that the As has low bioavailability. Fishing is important in the area both for local people as well as for tourists. The low bioavailability of As is verified by a few analysis of fish, pike and trout, in which the As content is relatively low and consisting of predominantly organic species like MMA, DMA and arsenobetaine. Thus in spite of elevated As contents in sediments and in water the As does not seem to pose a health risk for fish consumers.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Multidisciplinär geovetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geosciences, Multidisciplinary (hsv//eng)

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ref (ämneskategori)

kon (ämneskategori)