北方寒冷地区冻融期河岸缓冲区土地利用结构对河流水质的影响

以松花江哈尔滨段为研究区域,基于2014—2015年哈尔滨市6个国控水质监测断面逐月水质监测数据和2014年秋季ETM遥感数据,通过不同空间尺度和土地利用类型划分,利用冗余分析等方法研究土地利用结构在北方寒冷地区冻融期对河流水质的影响,结果表明:松花江流域哈尔滨段水质状况整体状况一般,氮污染比较严重,融水期COD与BOD_5高于冰封期,冰封期氮、磷含量高于融水期;冻融期河岸带100、200、500、900、1500 m缓冲区这5种尺度下,对河流水质指标影响最显著的土地利用方式为水域和建设用地,影响最大的空间尺度为100 m缓冲区,200 m缓冲区次之.其中建设用地和旱田与除DO以外的任何水质指标呈正相关,水域则与其呈负相关.融水期水质对土地利用结构的响应关系强于冰封期.在冰封期,水域对NH_3-N影响较大呈显著负相关,建设用地对TN影响较大呈显著正相关.在融水期,建设用地对COD影响较大呈显著正相关.在流域管理中,针对植被覆盖率低、建设用地占比高的流域应加强冻融期土地利用管控,合理开发建设用地.

Influence of land use structure in riparian buffers on river water quality during the freezing and thawing period in Northern Cold Region

This paper took Harbin section of Songhua River as the study area. Based on the monthly water quality monitoring data of six national controlled water quality monitoring sections in Harbin from 2014 to 2015 and ETM remote sensing data in the autumn of 2014, this paper explored the influence of land use structure on the river water quality in the northern cold region during the freezing and thawing period by methods such as redundancy analysis through different spatial scales and division of land-use types. The result indicates:the overall water quality of the Songhua River of Harbin is general, with relatively serious nitrogen pollution; COD and BOD₅ in the meltwater season are higher than those in the icebound season, whereas the content of nitrogen and phosphorus in the icebound season is higher than that in the meltwater season; as to the buffers in the riparian zone with five scales (100, 200, 500, 900 and 1500 m) during the freezing and thawing period, the land-use type which has the most significant impact on the river water quality index is water area and construction land, and the most influential spatial scale of buffer is 100 m, followed by 200 m. Among the land-use types, construction land and dry farmland are positively correlated with all water quality indexes except DO; whereas water area shows a negative correlation with them. The response relation of water quality with land use structure in metlwater season is stronger than that in icebound season. During the icebound season, water area has a relatively large impact on NH₃-N, which presents a significantly negative correlation; whereas construction land has a relatively large impact on TN, which presents a significantly positive correlation. During the meltwater season, construction land has a relatively large impact on COD, which presents a significantly positive correlation. With respect to watershed management, control on land use in watersheds with low vegetation coverage and high ratio of construction land should be strengthened during the freezing and thawing period, and construction land ought to be developed reasonably.