赣江流域土地利用结构及社会经济对河流可溶性重金属含量的影响

基于以2014年Landsat 8卫星影像以及2014年1月和6月野外采样数据并结合GIS技术与统计方法,分析赣江流域土地利用格局与河流水体可溶性重金属分布的关系.结果表明:赣江流域土地利用类型与可溶性重金属含量具有显著相关性,其中城镇建设用地与赣江可溶性重金属含量关系最为密切.林地与草地的面积比例与可溶性重金属呈现显著的负相关,但这种负相关仅存在于河流下游的较低坡度区域.整个子流域、河流缓冲区及坡度3个尺度上土地利用结构与河流可溶性重金属含量的关系,具有很大的差异,不同坡度大小上土地利用结构能较好地反映人类活动强度.低坡度区域由于人类活动强度较大,因此低坡度区域内土地利用结构对河流可溶性重金属含量具有更大的影响.社会经济要素和河流可溶性重金属含量的关系密切,工农业活动的强弱与赣江可溶性重金属含量的高低存在明显的对应关系.赣江流域土地利用结构与河流可溶性重金属含量间的关系存在季节的差异,总体上,丰水期与土地利用结构关系更显著.

Effect of land use structure and social economy on concentrations of dissolved heavy metal in Ganjiang River Basin

Land use structure, which reflects the extent of anthropogenic activities, can greatly affect the concentration of pollutant in the river. This study explored the relationship between the land use structure, social economy and concentrations of the dissolved heavy metal based on satellite image, field samples collection and correlation analysis. The results show that concentrations of the dissolved heavy metal were greatly influenced by land use structure and urbanization was the major factor. Forest and grassland had significantly negative effect on concentrations of the dissolved metal, which only happened in the downstream with gentle slope, but not in the upstream with steep slope. Those with steep slope did not reduce the concentration of dissolved heavy metal possibly due to the presense of pollution source in the upstream. The effect of land use structure on the water quality varied at three different spatial scales, namely entire basin, buffer zones and slope. Land use structure in different slope reflected the differences of human activities, especially in the area with low slope and intense human activities greatly affected the concentration of dissolved heavy metal. The steep areas, which are widely distributed and little influenced by human activities, disturbed the effect of land use structure on concentration of dissolved heavy metal. In addition, concentrations of dissolved heavy metal were greatly affected by social economy. The level of dissolved heavy metal in Ganjiang River corresponded with the extent of industrial and agricultural activities. The relationships between land use structure and concentrations of dissolved heavy metal also varied with seasonal change, which was more significant in wet season than in dry season.