Matrix-bound phosphine, phosphorus fractions and phosphatase activity through sediment profiles in Lake Chaohu, China

The distribution patterns of matrix-bound phosphine (MBP), phosphorus (P) fractions and neutral phosphatase activity (NPA) were investigated through five sediment profiles in Lake Chaohu, China. MBP was discovered in all sediment profiles within the concentration range of 1.58-50.34 ng kg(-1). These concentrations exhibited a consistent vertical distribution pattern in all profiles, and higher concentrations generally occurred in surface sediments. MBP concentrations showed a significant positive correlation with P fractions, total nitrogen (TN), Cu and Zn under lower levels of inorganic phosphorus (<0.6 g kg(-1)), organic phosphorus (<0.2 g kg(-1)), TN (<0.13%), Cu (<25 mg kg(-1)) and Zn (<150 mg kg(-1)), but no statistically significant correlations were obtained under higher levels. A multiple stepwise regression model ([MBP]=1.36[NPA]-6.21[pH]-0.06[Zn]+0.75[Cu]+49.86) was obtained between MBP concentrations and environmental variables, and MBP concentrations showed a strong positive correlation with NPA (P<0.0001). This indicates that the production of sediment MBP was controlled by microbially mediated processes in Lake Chaohu. This model could be used to predict MBP levels in the sediments. Our results indicate that MBP levels could not be used as indicators for the degree of lake eutrophication. The study of sediment MBP, P factions and NPA will improve our understanding of P cycling and their environmental significance in the eutrophic Lake Chaohu.