洪泽湖出入河流及湖体氮、磷浓度时空变化(2010-2019年)

Spatio-temporal variations of total nitrogen and total phosphorus in lake and inflow/outflow rivers of Lake Hongze,2010-2019

基于2010-2019年洪泽湖湖体水质逐月监测数据,筛选出影响湖体水质的主要污染物指标为总氮(TN)和总磷(TP);选取洪泽湖周边25条主要入湖河流和2条出湖河流在2019年10月2020年9月的监测数据,探讨河流外源性输入对不同湖体区域氮磷的影响及其水期变化规律.结果发现:①湖体TN、TP浓度长期居高不下,年均浓度范围分别在1.39~1.86、0.080~0.171 mg/L波动.主要入湖河流TN、TP时空平均浓度(1.92~5.70和0.114~0.181 mg/L),均高于同区域湖体(1.15~1.46和0.088~0.101 mg/L),其中北部入湖河流肖河、马化河和五河与临近湖区TN、TP浓度呈现显著正相关,是影响北部湖体TN、TP浓度的主要河流;南部入湖河流维桥河和高桥河是临近湖区非极端降雨期TN、TP的主要来源.②调水工程对湖体及入湖河流TN、TP浓度分布影响显著,调水期湖体沿调水方向TP浓度逐渐上升,TN浓度则呈现先降后升的趋势,南部入湖河流维桥河和高桥河TN浓度达到水期峰值,分别为10.69和9.90 mg/L.③极端降雨期入湖河流的TN、TP浓度显著高于其它水期,由于湖体对TN、TP的富集作用不同,TP浓度呈现中间高,四周低,而TN浓度呈现沿洪水流向逐渐降低的规律.

Based on the monthly monitoring data of Lake Hongze from 2010 to 2019,the main pollutant indicators including total nitrogen(TN)and total phosphorus(TP),which affect the water quality of Lake Hongze,were studied.25 main inflow rivers and 2 outgoing rivers around Lake Hongze were selected for monitoring from October 2019 to September 2020,and the impact of exogenous river input on lake nitrogen and phosphorus in different lake regions and their water period variation rules were discussed.The results showed that:(1)the concentration of TN and TP in Lake Hongze remained in a high level for a long time.The annual average concentration of TN and TP fluctuates in the range of 1.39-1.86 mg/L and 0.080-0.171 mg/L,respectively.The temporal and spatial average concentrations of TN and TP in the main inflow rivers(1.92-5.70 mg/L and 0.114-0.181 mg/L)are higher than the lake in the same regions(1.15-1.46 mg/L and 0.088-0.101 mg/L).The concentration of TN and TP in Xiaohe River,Mahua River and Wuhe River,which are the main rivers that affect the concentration of TN and TP in Lake Hongze,is significantly positively correlated with that in the adjacent lake.Weiqiao River and Gaoqiao River near the southern regions of Lake Hongze are the main contributors of TN and TP during non-extreme rainfall period.(2)The water transfer project has a significant impact on the concentration distribution of TN and TP in the body of Lake Hongze and main inflow rivers.During the water transfer period,the TP concentration of the lake gradually increased along the water transfer direction,while the TN concentration showed a trend of first decreasing and then increasing.TN concentrations of the Weiqiao River and Gaoqiao River in the south reached the peak of the water period,which were 10.69 mg/L and 9.90 mg/L respectively.(3)The concentration of TP and TN in the inflow rivers during the extreme rainfall period is significantly higher than that in other water periods.Due to the different enrichment effects of lakes on TN and TP,TP concentration was high in the middle and low around it,while TN concentration showed a law of gradual decrease along the flood flow direction.