Potential Impacts of Climate Change on Phosphorus and DO in Yuqiao Reservoir

Abstract

The climate indicators and water quality parameters, e.g. total phosphorus (TP) and dissolved oxygen (DO) in a period of 20 years (1992-2011) were analyzed to explore potential impacts of climate change on nutrients and DO. Firstly, the study period was divided into two decades: 1992-2001 cool decade and 2002-2011 warm decade for the Mann Kendall statistical test and the accumulative anomaly test. Secondly, the significance of climate parameters in seasonal variations was analyzed by comparing the nonlinear trends of parameters using non-parametric regression in two decades respectively. Finally, comparing the relationship between climate indicators and water quality parameters for two decades, the potential impacts were investigated by double-k method. The results showed that the higher temperature potentially decreased TP concentrations in winter and spring and DO concentration in autumn. However, the increases in air temperature in winter and spring increased DO concentration. The increase in wind speed was most likely to increase TP and DO concentrations in all four seasons. A positive correlation between precipitation and TP concentration was found in all four seasons. The DO concentration declined when rainfall decreased in summer. The difference in temporal trends between inflow P loading and concentrations in reservoir indicated the potential impacts of climate change on TP concentration. The field data in TP and macrophytes biomass in spring was the evidence supporting that TP in spring was likely to decline when the air temperature increased. The study provides a reference for the impacts and mechanisms of climate change on water quality in Yuqiao reservoir.