Distribution and chemical fractionation of arsenic in surficial sediments of the Lami coastal environment in Fiji

A case of arsenic contamination has recently been detected in the Lami coastal environment during the course of a heavy metal monitoring in Fiji's coastal environment. Twenty two surficial sediment samples were sampled during the 2008–2009 period, extracted for arsenic and analysed using graphite furnace atomic absorption spectrometry. Two sites within the Lami estuary recorded the highest As levels of 334 and 282 mg kg–1 as dry weight in sediments samples, which has greatly exceeded the local and global average background concentrations. Chemical fractionation studies using a standard sequential protocol showed that As is mostly associated with residual (strong acid extractable) phase of the sediments, however significant amounts of As were also detected in bioavailable (exchangeable, water and acid soluble), reducible and oxidisable fractions. Comparison with standard sediment quality guidelines (SQGs) indicate that As levels are likely to be highly toxic to biota, hence further ecotoxicological studies are warranted to evaluate possible environmental effects on the aquatic environment.