河流输入对博斯腾湖溶解性有机物组成的时空影响

Temporal and Spatial Effects of River Input on Dissolved Organic Matter Composition in Lake Bosten

博斯腾湖是我国西北干旱区最大的内陆吞吐型淡水湖,近年来随着流域人类活动与污废水排放的增加,湖泊生态系统和周围居民的饮用水安全已经受到了严重影响,需重点关注河流输入对湖泊水质的影响。对夏秋两季的实测有色溶解有机物(CDOM)三维荧光光谱进行平行因子分析,解析出博斯腾湖CDOM三种组分:陆源类腐殖质组分C1、类酪氨酸组分C2和类色氨酸组分C3;同时,基于Pearson相关性分析了夏秋两季河流输入对博斯腾湖DOM的影响。结果表明,不同季节河流输入对博斯腾湖DOM的影响不同且与河流水质季节性变化直接相关。夏季开都河入湖水主要来自冬季积雪融水,携带大量陆源类腐殖质入湖,而秋季主要为冰川融水,随着入湖流量增加,携带陆源类腐殖质含量降低,整体表现为河口附近DOM浓度夏季高、秋季低。解析出的三种组分C1、 C2与C3在湖西部开都河和黄水沟入湖处含量较高,且三种组分受季节性的影响较为相似。同时对开都河河口附近采样点和其他区域采样点的DOM与电导率进行相关性分析,发现外部河流输入对博斯腾湖DOM的影响主要集中在河口附近,且河口附近区域DOC与CDOM关系显著,可以先遥感反演CDOM再估算DOM含量。研究不同季节河流输入对博斯腾湖溶解性有机物组成的影响对保护湖泊生态环境和提升湖泊水质具有十分重要的意义。

Lake Bosten is the largest inland throughput freshwater lake in the northwest arid zone of China.In recent years,the lake ecosystem and the drinking water safety of the surrounding residents have been seriously affected by the increase in human activities and wastewater discharge in the basin,and the impact of riverine input on the lake water quality needs to be focused on.In this study,the three-dimensional fluorescence spectra of coloured dissolved organic matter(CDOM)measured in summer and autumn were analysed in parallel.Three fractions of CDOM from Lake Bosten were identified:terrestrial humic fraction C1,tyrosine-like fraction C2 and tryptophan-like fraction C3.The effect of river input on the DOM of Lake Bosten was also analysed based on Pearson correlation.The results show that river input’s influence on Lake Bosten’s DOM differs between seasons and is directly related to the seasonal changes in river water quality.In summer,the water entering the lake from the Kaidu River mainly comes from winter snowmelt and carries a large amount of terrestrial humus into the lake,while in autumn,it is mainly glacial meltwater.The content of terrestrial humus is reduced as the flow into the lake increases,showing that the overall DOM concentration near the estuary is higher in summer and lower in autumn.The three components C1,C2 and C3,were found to be more abundant in the western part of the lake where the Kaidu River and the Yellow Water Ditch enter the lake,and the three components were similarly affected by seasonality.The correlation between DOM and conductivity was also carried out at sampling points near the mouth of the Kaidu River and other areas.It was found that the influence of external river input on the DOM of Lake Bosten was mainly concentrated near the mouth of the river,and the relationship between DOC and CDOM in the area near the mouth of the river was significant so that the CDOM could be inferred by remote sensing before estimating the DOM content.The study of the influence of river inputs on the composition of dissolved organic matter in Lake Bosten in different seasons is of great importance to protect the lake’s ecological environment and improve the lake’s water quality.