Influence of climate change and human activity on total nitrogen and total phosphorus: a case study of Lake Taihu, China

Xu X, Liu H, Jiao F, Ren Y, Gong H, Lin Z, and Huang C. 2020. Influence of climate change and human activity on total nitrogen and total phosphorus: a case study of Lake Taihu, China. Lake Reserv Manage. XX:XXX-XXX. Climate change and human activities can influence lake total nitrogen (TN) and total phosphorus (TP), affecting the overall health of the lake. These factors must be considered for planning and management of lakes in order to maintain their ecosystem integrity and sustain societal development. Using the Ensemble Empirical Mode Decomposition Method (EEMD) and the nonparametric Mann-Kendall test, the changes of TN and TP and their relationship to climate change and human activities were quantitatively evaluated on multiple time scales ranging from 1952 to 2010 using Meiliang Bay of Lake Taihu (China) for a case study. Patterns of TN change could be divided into 4 time scales: 2.73, 5.89, 25.33, and 45 yr, with an evident increasing long-term trend. Patterns of TP change were divided into 2.49, 6.4, 11.5, and 43 yr time scales with an increasing long-term trend. On short time scales, TN and TP were positively correlated with gross domestic product (GDP) and urban area, and negatively correlated with crop area and animal production. For the long-term trends, TN and TP were positively correlated with temperature, GDP, urban area, and animal production, and negatively correlated with precipitation and crop area. Both TN and TP abruptly changed in 2000, consistent with the abrupt changes in temperature, precipitation, and urban area. Collectively, results revealed that specific human activities in the watershed affected TN and TP in the sediments both on short-term and long-term scales, while global climate change affected TN and TP in the sediments on long-term scales. These results suggest that climate change and human activities must be considered to manage and protect lakes.