沙湖的水环境容量和污染物总量控制

Environmental Capacity and Total Pollutant Control in Shahu Lake

[目的]探明宁夏回族自治区沙湖富营养化状态及计算主要污染的水环境容量,为沙湖入湖污染负荷的削减和水环境保护提供一定依据。[方法]于2015-2017年冬(1月)、春(4月)、夏(7月)、秋(10月)监测了沙湖水体理化指标。采用综合营养状态指数法对其富营养化状态进行了评价,采用沃伦威德(Vollenweider)模型和狄龙(Dillion)模型计算了4种不同水质目标情景下的高锰酸盐指数、总氮和总磷的水环境容量。[结果] 2015-2017年沙湖富营养化状态总体上为春、冬季轻度富营养化,夏、秋季中度富营养化;情景二和三水质目标下沙湖2015-2017年高锰酸盐指数,总氮和总磷水环境容量剩余量均为0;情景四水质目标下沙湖2015-2017年总磷的水环境容量剩余量均为0,高锰酸盐指数的水环境容量有剩余量,总氮的水环境容量2015年有剩余量,2016-2017年剩余量为0。在2017年水质现状的基础上,达到Ⅲ类水质要求高锰酸盐指数、总氮和总磷分别消减655.97 t,39.27 t和1.41 t,消减率分别为112.89%,45.58%和37.60%;达到Ⅳ类水质要求高锰酸盐指数、总氮和总磷分别消减0,15.83 t和0.94 t,消减率分别为0,18.37%和25.07%。[结论]沙湖水体呈现一定程度的污染,已达到富营养化状态,高锰酸盐指数、总氮和总磷的水环境容量大于目标要求的水环境容量,应该及时进行治理和保护。

[Objective] This study aims to determine the eutrophication status of Shahu Lake, Ningxia Hui Autonomous Region, and to calculate the environmental capacity of the lake for major pollution as a means of providing a basis for reducing the pollution load and improving the environmental protection of Shahu Lake.[Methods] Water samples were collected in January, April, July, and October during 2015-2017 to measure physical and chemical parameters. A comprehensive eutrophic state index was applied to assess the trophic status, and the Vollenweider and Dillon model was used to analyze the environmental capacity of permanganate index(CODMn), total nitrogen(TN), and total phosphorus(TP) of the lake under four different water quality target scenarios. [Results] During 2015-2017, Shahu Lake was mildly eutrophic in spring and winter, and moderately eutrophic in summer and autumn. In scenarios two and three of the water quality targets, the remaining environmental capacities for CODMn, TN and TP were zero. In scenario four, the remaining environmental capacity of the lake for TN was zero, whereas that for CODMn still had a remaining capacity. The environmental capacity of TN had a surplus in 2015, but this was reduced to zero in 2016-2017. On the basis of the water quality in 2017, to attain class Ⅲ water quality requirements, CODMn, TN, and TP should be reduced to 655.97, 39.27, and 1.41 tonnes, respectively, which correspond to reduction rates of 112.89%, 45.58%, and 37.60%, respectively. In order to attain class Ⅳ water quality requirements, the CODMn, TN and TP should be reduced by 0.0, 15.83, and 0.94 tonnes, respectively, which correspond to reduction rates of 0%, 18.37%, and 25.07%, respectively. [Conclusion] Shahu Lake has certain degree of pollution and has reached a state of eutrophication, the environmental capacities of CODMn, TN, and TP in the lake are greater than the target requirement, and should be managed and protected.