Evaluation Of Water Quality In Typical Areas Of The Lake Ebinur Watershed And Its Relationship With Land Use/Cover-landscape Patterns

River runoff from the Ebinur Lake basin is the main source of irrigation water for the northwest region of Xinjiang and the main source of supply to maintain the ecological balance of the entire Bortala Mongol Autonomous Prefecture,occupying an important social and ecological location.The watershed is through Wenquan County,Bole City,Jinghe County and other areas,influenced by local farming and livestock production and lifestyle,its main rivers into the lake Jing River and Bortala River receive domestic and industrial sewage from the surrounding towns,and finally from the upper to lower reaches into the Ebinur Lake,resulting in the water quality of Ebinur Lake is worrying.Land use/cover and landscape patterns,as important manifestations of human activities,are good indicators of non-point source pollution in watersheds,and have important theoretical and practical significance for regional land use planning and protection of the surface water environment.Based on this study,the spatial and temporal changes in surface water quality in the study area under dry and wet seasons(dry season-October2017,August 2018,and wet season-May 2017,May 2018)were studied using the typical areas of the Lake Ebinur basin(Jing River,Bortala River)as the main object of study,and the water quality evaluation index,parallel factor analysis method and mathematical statistics were used to study the spatial and temporal changes in surface water quality in the study area under dry and wet seasons,while Land use/cover and landscape pattern data of the study area were used to analyze various factors affecting water quality and to explore the impact of land use/cover type and landscape pattern changes on water quality under the influence of human and microbial activities.The main results of the study are as following:(1)The results of surface water characteristics analysis and evaluation in the study area showed that,except BOD₅,NH₄⁺-N,volatile phenol and sulfate,the other water quality parameters also showed a certain change rule in the dry and wet seasons.The value of TP content was generally higher in the whole Bortala River flow,and the high value was mainly concentrated in the middle reaches of the urban densely populated areas.An evaluation of the CWQI values of the Jing and Bortala rivers shows that the overall water quality is poor in the typical area of the Lake Ebinur basin during the dry and wet seasons.(2)The parallel factor method,three-dimensional fluorescence region integral method and fluorescence index were used to analyze the variation of DOM in rivers in the study area during the dry and wet seasons.It can be seen that the change of water quality in Jing River and Boltala River during the dry and wet seasons is mainly affected by the joint influence of microbial activities and biological or bacterial activities.Under the influence of the unique production and life style in Jing River and Boltala River,the discharge of nitrogen fertilizer during the busy farming season is the main reason for the change of FI,BIX and HIX in the water body.(3)There are certain trends in land use/cover in the study area during the dry and wet seasons from 2017 to 2018,which are influenced by a combination of seasonal and environmental(both anthropogenic and environmental factors)factors.The transformation between other land types,saline and arable land was more obvious during the dry season in Jing River and Boltala River.The overall change in landscape pattern characteristics is characterized by low landscape fragmentation in the middle and lower reaches of the Jing and Bortala rivers during the dry season,a decrease in the richness of landscape types,a gradual decrease in the interaction of patches between different types,a decrease in the overall complexity of patches,and an increase in the dominance of dominant species in the landscape,an increasing integrity and totality of the landscape,and an increase in the resistance of the landscape to human activity interference;In the wet season,the landscape boundaries and patch shapes in the middle and lower reaches of the two rivers are more complex,the landscape fragmentation is higher,and the high value points with more obvious changes are mainly concentrated in the densely populated areas of the towns.The increase of landscape fragmentation in the dry and wet seasons of the two rivers is accompanied by significant changes in sulfate,NH₄⁺-N and mineralization.