Environmental impacts in the Jianghan plain: Evidence from lake sediments

There is growing concern about the environmental impact of rapid economic g rowth in China. The problem is compounded by the scarcity of baseline data on the state of China's natural environment. As a step towards solving this problem, palaeolimnological methods have been applied to seven lakes in th e Jianghan Plain, China, to evaluate recent changes in human impact. Lake sediment cores show enhanced concentrations of fossil fuel derived sph eroidal carbonaceous particles (SCP) and Pb at all sites across the Jiangha n Plain. The distribution of these industrial contaminants shows the overwh elming influence of the industrial cities. Wuhan dominates the fossil fuel derived pollution, while the copper smelter at Daye dominates the heavy met al pollution. Analysis of sediment diatom assemblages indicates mean total phosphorus concentrations of greater than 40 mu g L-1 P in the lakes of the more intensely agricultural western part of the Jianghan Plain. The sedime nt concentration profiles for biogenic elements at these sites indicates a post-1960 eutrophication. Evidence for eutrophication in the eastern lakes is much weaker, though some evidence is present at all sites. The tracers of industrial pollution (Pb and SCP) correlate with Mn in the m any of the lake sediments. This is compatible with both soil acidification, and soil gleyification due to intensified rice production.