巩乃斯河流域氮素时空分布及其对土地利用类型的响应OA

The land use types of Gongnaisi River Basin are diverse,whereby river water quality is susceptible to anthropogenic impacts,and the problem of nitrogen pollution has been prominent.Taking the basin as the research object,the spatio-temporal distribution of nitrogen in river water,the structure of land use type in the basin and its influence on river nitrogen were analyzed.The results showed that the nitrogen concentrations in the mainstream of the Gongnaisi River Basin in spring were generally in the order of downstream>midstream>upstream,while the concentrations of all nitrogen forms except for NH4+-N reached the peak in the midstream for the tributaries.In autumn,the PN concentration was the highest in the upper reaches of the mainstream,while that in the tributaries peaked in the midstream,with other indicators of the mainstream and tributaries showing a trend of downstream>midstream>upstream.Nitrogen concentrations showed significant seasonal variations,with higher levels in spring than in autumn,and significant seasonal differences were observed in nitrogen concentrations across different river reaches.Land use parameters within the 5 km riparian buffer zone exhibited a higher contribution rate to river nitrogen levels.The overall nitrogen concentration in the river was significantly positively correlated with the proportions of farmland and construction land,yet significantly negatively correlated with those of glacial snow,desert and grassland.The conclusions from the quantitative study on land use indices and water quality at multiple spatiotemporal scales in the Gongnaisi River Basin can provide a scientific basis for the precise regulation and ecological protection of water quality in this basin,and offer guiding significance for practical water environment governance.