Mercury Concentrations in Coastal Heath Forests of Peninsular Malaysia

Mercury (Hg) is a globally distributed bioaccumulative neurodegenerative pollutant. The main way Hg enters the ecosystem is via stomatal uptake of gaseous Hg and subsequent sequestration into the soil via leaf litterfall. Thus, determining litterfall Hg concentrations will help our understanding of a key flux in Hg biogeochemistry. Concentrations of Hg in terrestrial ecosystem compartments are not well known in South-east Asia, so to rectify this deficit we determined Hg concentrations in litterfall and soil in two contrasting forest types in Terengganu, Peninsular Malaysia. We collected litterfall and soils (bulk: < 2 mm and fine: < 63 μm) from forest and heath vegetation types over coarse sandy soils and assessed Hg by an acid digestion (HCl and HNO3) and hydride generation ICP–OES technique. Litterfall Hg was 42.6 ± s.e. 2.17 ng g−1, and bulk soil Hg was 10.1 ± 2.30 ng g−1, whereas the fine soil fraction was 173 ± 20.9 ng g−1. There were correlations between Hg and macronutrient elements (C, N, P, K, Ca, Mg and S) in soil but not leaves. Total Hg return to the soil via litterfall was estimated as 16.8 μg Hg m−2 yr−1 which compares well with other global studies. Overall, our research implies that this ‘unpolluted’ location in Malaysia has Hg input comparable to other global studies, but we note that other forests in this region with greater biomass may return more Hg to the soil.