三峡库区多时空尺度土地利用和景观格局对水质的影响

为了探究三峡库区水质对不同尺度的土地利用和景观格局的响应，基于三峡库区2019—2021年7个断面的水文与水质数据和2020年土地利用数据，分析了水质时空异质性、多尺度河岸带缓冲区内土地利用和景观格局特征，同时利用相关性分析和冗余分析（RDA）确定了土地利用和景观格局对水质指标的影响及最佳影响尺度，并采用偏最小二乘回归（PLSR）探究了最佳影响尺度下的关键影响因子。结果表明：三峡库区水质状况整体稳定，枯水期的水质优于丰水期，水质状况主要受到面源污染、支流汇入、磷矿产业和城镇化的影响；小尺度缓冲区内景观斑块破碎化较严重，但多样性较高，耕地是库区的优势景观类型，其破碎化程度的增加有利于水环境的改善；林地和草地在枯水期对水环境的净化作用优于丰水期，而水域是河流氮磷污染物的主要来源；整体上土地利用和景观格局对水质指标的解释能力在丰水期高于枯水期，且在300 m缓冲区尺度下解释能力最强，其中耕地、草地、水域和斑块密度（PD）是影响水质指标的关键变量。

Impact of land use and landscape pattern on water quality on multiple temporal and spatial scales in the Three Gorges Reservoir area

To investigate the response of water quality to land use and landscape pattern of different scales, this study analyzed the spatial and temporal heterogeneity of water quality and the characteristics of land use and landscape patterns in multi-scale riparian buffer zones based on the hydrological and water quality data of seven transects in the Three Gorges Reservoir area from 2019 to 2021 and the land use data in 2020. Correlation analysis and redundancy analysis (RDA) were also used to determine the effects of land use and landscape patterns on water quality indicators and the optimal scale of influence. Then, partial least squares regression (PLSR) was used to explore the key influencing factors under the optimal scale of influence. The results show that the overall water quality condition in the Three Gorges Reservoir area was stable, the water quality in the dry water period was better than that in the wet period, and the water quality condition was mainly affected by non-point source pollution, tributary confluence, the phosphorus industry and urbanization. Furthermore, the landscape patches in the small-scale buffer zone were severely fragmented, but more diversified; cultivated land was the dominant landscape type in the reservoir area, and its increased fragmentation was conducive to improving the aquatic environment; forest and grassland had a better purifying effect on the water environment in the dry period than in the wet period, whereas waters were the main source of nitrogen and phosphorus pollutants in the river. Generally, the explanatory ability of land use and landscape patterns on water quality indicators was higher in the wet period than in the dry period, and was strongest on the 300 m buffer scale, where cultivated land, grassland, waters and patch density (PD) were the key variables influencing the water quality indicators.