河流污染物输送对巢湖水质影响研究

The Influence of Pollutant Inputs from the Major Tributaries on Water Quality of Chao Lake

研究采用零维模型,以Ⅲ类水为控制目标,对巢湖CODMn、TP、NH3-N的水环境容量进行了估算,同时研究了入湖支流污染物输送对巢湖水质的影响。结果表明,Ⅲ类水质目标下巢湖CODMn、TP、NH3-N的水环境容量分别为6.21×104、0.04×104、0.85×104t·a-1。CODMn年均背景储量为3.17×104t·a-1,占巢湖水环境容量的51%,而TP与NH3-N年均背景储量均大于其水环境容量。因此,在Ⅲ类目标水质下,巢湖仅允许有CODMn的排放,且年均允许排放量为3.04×104t·a-1。入湖支流每年向巢湖输送CODMn4.56×104t、TP 0.25×104t、NH3-N 5.15×104t,其中CODMn年均输送总量小于其水环境容量,但大于允许排放量。因此,入湖支流污染物的输送会加剧巢湖水质恶化,削减支流污染物排放成为控制巢湖水质恶化的关键途径。

The tributaries of a lake have great impacts on its water quality. In this study, water environmental capacities of CODMn, TP, and NH3-N in Chao Lake were calculated using the zero-dimension model based on the national level Ⅲ water quality standard. At the same time, the influence of pollutant inputs from the major tributaries of Chao Lake on its water quality was assessed. Results showed that water environmental capacities of CODMn, TP, and NH3-N in Chao Lake were 6.21×104t·a-1, 0.04×104t·a-1, and 0.85×104t·a-1, respectively. The background load of CODMn accounted for 51% of its water environmental capacity, but that of TP and NH3-N all exceeded their water environmental capacity. To meet the standards for the national level Ⅲ water quality, Chao Lake can receive only 3.04×104 t·a-1 of CODMn, but no more TP or NH3-N. Annual inputs to Chao Lake from its major tributaries were estimated to be about 4.56×104t CODMn, 0.25×104t TP, and 5.15×104t NH3-N, all greater than their allowable inflow loads. Therefore, it would be critical to reduce pollutant inflow into Chao Lake from its tributaries for improving Chao Lake water quality.