大黑汀水库水质时空变化特征及下游引水策略

为探究大黑汀水库2017年养鱼网箱拆除后水质特征,于2018年分季节采集水库表层和分层水样分析水库水质时空变化特征。结果表明:大黑汀水库表层水体总氮在冬季最高,总磷在夏季最高,硝态氮是溶解性无机氮中的主要成分;大黑汀水库总氮、硝态氮、总磷和磷酸盐质量浓度总体上都表现出上游最高、中游次之、下游最低的空间分布特征,氨氮和亚硝态氮则相反;垂向上主要表现为夏季总磷质量浓度底层大于表层,与温跃层及溶解氧水平有关;养鱼网箱拆除后显著降低了水库总磷和磷酸盐质量浓度,氨氮质量浓度也显著降低,总氮和硝态氮质量浓度无显著变化;氮磷比表明磷是该水库水体富营养化的限制因子,因此养鱼网箱拆除能有效控制该水库富营养化进程;根据水质时空分布特征,下游引水应避免在冬季取水,引水高度上应选择从坝前中层水柱取水。

Spatio-temporal characteristics of water quality in Daheiting Reservoir and downstream water transfer strategy

In order to explore the water quality characteristics of Daheiting Reservoir after the removal of fish cage in 2017, the surface water samples and stratified water samples of the reservoir were collected in 2018 to analyze the spatio-temporal characteristics of the water quality of the reservoir. The results show that the total nitrogen and total phosphorus in the surface water of Daheiting Reservoir are the highest in winter and summer, and nitrate nitrogen is the main component of dissolved inorganic nitrogen. The spatial distribution characteristics of total nitrogen, nitrate nitrogen, total phosphorus and phosphate concentration in Daheiting Reservoir are the highest in the upper reaches, the second in the middle reaches and the lowest in the lower reaches. Ammonia nitrogen and nitrite nitrogen are opposite. Vertically, the total phosphorus concentration in the bottom layer is higher than that in the surface layer, which is related to thermocline and dissolved oxygen level. After the removal of the fish cages, the concentration of total phosphorus and phosphate, ammonia nitrogen and nitrate nitrogen in the reservoir decreased significantly, but there was no significant change in the mass concentration of total nitrogen and nitrate nitrogen. The N/P ratio shows that phosphorus is the limiting factor of the reservoir, so the removal of fish cages can effectively control the eutrophication process of the reservoir. According to the spatio-temporal distribution characteristics of water quality, the downstream water diversion should avoid taking water in winter, and the middle water column in front of the dam should be selected as the water diversion height.