博斯腾湖水质年内时空特征及其驱动因素分析

Spatial-Temporal Variation of Water Quality and Its Driver-Factors Analysis in Bosten Lake, China

摘要: 湖泊在干旱区水资源中发挥着重要的作用，而水质恶化是湖泊水资源开发利用的重大威胁之一。本研究以我国最大的内陆淡水湖——博斯腾湖为例，分析了湖泊年内水质时空变化特征，并探讨了其驱动因素。研究结果表明：博斯腾湖的主要污染物是TDS，COD和TP，且TDS年内空间分布上呈现出西南低、东北高的趋势，COD在空间上四月和六月表现为西南低、东北高，在八月和十月表现为西南高、东北低，TP在空间上四月表现为西南低、东北高，在十月表现为西南高、东北低；NH3-N含量较低，且空间分布均匀，不是威胁博斯腾湖水质的主要因素。博斯腾湖水质存在显著年内分布差异，六月和八月水体TDS和COD含量较高而TP含量较低，四月和十月TDS和COD含量较低而TP含量较高。相较于外源污染物，长期滞留湖区的内源污染物对博斯腾湖年内水质变化的影响更显著，而温度是加剧博斯腾湖水质年内差异的主要催化剂。因此，通过调节年内不同温度时段下的湖泊水位，可以有效调控博斯腾湖年内水质状况。

Abstract: Lakes in the arid and semi-arid regions play a critical role in valuable water resources, while deterioration in water quality would threaten the societies, economies, biological diversity and fragile environment conservation in these areas. In this study, 68 monitoring points around the Bosten Lake, the largest inland freshwater lake in China, were established to investigate the spatial-temporal variation of water quality during the year. The results showed that the main pollutants of the lake were total dissolved solids (TDS), chemical oxygen demand (COD), and total phosphorus (TP), moreover, TDS content in the southwestern part of lake was generally lower than that in the eastern and northern part of lake; COD content in the southwestern part of lake was generally lower than that in the eastern and northern part of lake in April and June, but it in southwestern part of lake was generally higher than that in the eastern and northern part of lake in August and October; TP content in the southwestern part of lake was generally lower than that in the eastern and northern part of lake in April, but it in southwestern part of lake was generally higher than that in the eastern and northern part of lake in October. NH3-N content, which was evenly distributed in the lake area, was not the main contaminant in the Lake. Water quality in the Lake also showed a temporal distribution difference. The TDS content of the lake in June and August was higher than that in April and October, while the COD and TP contents were opposite to the TDS content. Allochthonous pollutants composed by the wastewater from agricultural irrigations and inflow from the rivers affected the spatial-temporal water quality, but this effect was not significant. Endogenous pollutants constituted the key reason for the spatial difference, and the solubility change of endogenous and exogenous pollutants caused by temperature mainly determined the annual change of water quality. The water quality of Bosten Lake could be improved by adjusting the water level of the lake in different temperature periods annually.