Refractory arsenic species in estuarine waters

Abstract
Total digestion of estuarine water samples by dry ashing shows that a significant fraction of dissolved arsenic does not form hydrides with sodium tetrahydroborane (NaBH4) and is therefore not detected by the normal hydride generation‐atomic absorption analytical technique. It is also refractory to alkaline digestion with sodium hydroxide. Sequential ultrafiltration suggests a molecular weight below 210 for this new arsenic fraction. The magnitude and molecular weight of this fraction may open new perspectives on the biogeochemical cycling of arsenic. Ecological reasons can explain the discrepancy between these findings and previous research.