入、出湖总磷负荷变化是影响鄱阳湖富营养化状态的关键性要素。基于2009—2018年水质水量监测资料,计算环鄱阳湖区的入、出湖总磷负荷,并采用算术平均法和加权平均法分别计算总磷年平均浓度,探明其时空变化规律;运用双累积曲线法、回归分析法,分析入湖水量和入湖总磷浓度与入湖总磷负荷之间的相关关系,揭示污染负荷的主要控制因素。结果表明:①加权平均法比算术平均法更能反映环鄱阳湖区入、出湖水量、水质时空差异性,入湖总磷多年平均浓度高低排序依次为饶河区(0.123 mg/L)>信江区(0.091 mg/L)>抚河区(0.069 mg/L)>赣江区(0.063 mg/L)>修水区(0.045 mg/L)。②环鄱阳湖区各水资源分区入湖总磷负荷多年平均值为98 514 t,低于湖口出湖总磷负荷年均值108 442 t,这主要是由于鄱阳湖滨湖区输入、湖体内源释放以及干湿沉降等均未进行计算。③赣江区和饶河区入湖总磷年负荷多年平均值分别为45 208 t和19 320 t,占五河(赣江、抚河、信江、饶河、修水)总入湖负荷的比重位居前二,其中赣江区的占比达46%。④各水资源分区月入湖总磷负荷与入湖水量存在显著的相关关系,说明各分区入湖总磷负荷在很大程度上受水量控制。

The variation of inflow and outflow total phosphorus (TP) loads is a key factor that affects the state of eutrophication in Poyang Lake. Based on the monitoring data of water quality and quantity from 2009 to 2018, the inflow and outflow TP loads around Poyang Lake were calculated, the arithmetic mean and the weighted mean of annual TP concentrations were attained, and their spatio-temporal variations were analyzed. Moreover, the relations of inflow water volume and TP concentration versus inflow TP load were examined by using double accumulation curve method and regression analysis method to reveal the dominant factors for pollution loads. Findings revealed: (1) Compared to arithmetic mean, the weighted mean concentration of TP better reflects the spatio-temporal difference of water quality and volume around Poyang Lake. Annual inflow TP concentration in Raohe River stood at the highest (0.123 mg/L), followed by Xinjiang River (0.091 mg/L), Fuhe River(0.069 mg/L), Ganjiang River (0.063 mg/L), and Xiushui River (0.045 mg/L). (2) Annual inflow TP load totaled 98 514 t, lower than outflow (108 442 t), omitting inputs from waterfront, sediment release, and dry-wet subsidence. (3) Ganjiang River(45 208 t) and Raohe River (19 320 t) were top two contributors to the total inflow TP load among the five rivers, of which Ganjiang River alone accounted for 46%. (4) Significant correlations were found between monthly inflow TP load and inflow water quantity across different water zones, indicating that TP loads are largely influenced by inflow water volume.