On the role of forested catchment in acid lake limnology

Özet

Delamere Lake is a small, shallow, acid lake (pH 4.5) on the edge of a coniferous forest in Cheshire, England. Its surface water catchment is 19 ha with water retention period of 53 weeks. The lake showed high total nutrients (total nitrogen, mean 2.2 ± standard error of the mean 0.1 mg $L^{-1}$; total phosphorus, 200 ± 14 μg $L^{-1}$) and humic acid content (water colour, minimum 40 mg Pt $L^{-1}$) and very high phytoplankton biomass (chlorophyll a, 290 ± 31 μg $L^{-1}$). The soil of the catchment was sampled to test its contribution to chemical characteristics of the lake water. The pH of the soil was found to be very low (3.20). Dissolved organic carbon content of soil was positively correlated with $NO _3-N$, SRP and $NH _4-N$ concentrations in the soil. The conifer-forested catchment was, therefore, suggested to be the main source maintaining low pH, high total nutrient concentrations and high humic content in the lake water.