Temporal and spatial distribution changing characteristics of exogenous pollution load into Dianchi Lake, Southwest of China

Based on the analysis of point source (PS) and non-point source (NPS) pollution emission characteristics of Dianchi Lake Basin, pollution load into the lake simulation models was constructed; the result should be useful for eutrophication researchers. The PS and NPS pollution load calculation results were added come exogenous pollution load into Dianchi Lake. Exogenous pollution load into Dianchi lake chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were 32876.86, 6571.64 and 429.37 t in 1990, respectively; were 33780.66, 10326.64 and 654.59 t in 2005, respectively; were 37717.00, 8597.01 and 546.48 t in 2012, respectively. Exogenous pollution load of Dianchi Lake temporal evolution and spatial distribution changing characteristics were analyzed that TN and TP pollution load were increased from 1990 to 2005, and they were decreased from 2005 to 2012, COD pollution load were increased in both periods. July or August was the most pollution load into the lake among months in 1990, 2005 and 2012. PS pollution was mainly concentrated in the northern area and the inside of Wuhua District and Guandu District. NPS COD pollution output increased was mainly the south of the northern area in Dianchi Lake Basin and reduced were mainly the north of the northern area, eastern area, western area and southern area; TN output of NPS increased in most regions, and only the central northern area had reduced regional distribution; TP output of NPS decreased mainly in the north of northern area, and increased in most other regions of the Basin from 1990 to 2012. The result should be meaningful to zoning control and classifying control of exogenous pollutants into the Lake.