常熟市水体氮负荷对土地利用方式的响应

为研究水环境变化对土地利用方式的响应,以常熟地区为例,利用ArcGIS10.0空间分析功能和SPSS相关性分析方法,对常熟市各土地利用类型和水体总氮含量进行了分析。结果表明:1990—2010年间常熟地区耕地和水域面积在持续缩减,建设用地和林地面积在增加;各土类状态指数(Di)大小依次为:建设用地林地草地耕地水域;建设用地面积的增加主要占据的是耕地和水域,水域面积的缩减主要被耕地占用;耕地面积与水体总氮含量呈显著性负相关关系(r=–0.959*,P0.05),说明种植型污染贡献比例在下降;林草地与水体总氮含量无显著相关性;建设用地与水体总氮含量呈显著性正相关关系(r=0.929*,P0.05),说明建设用地造成了点源污染。

Responses of Nitrogen Load in Water Body to Land Use Types in Changshu City

Changshu City was taken as the study area to explore the response of water quality variation to land use patterns. GIS space technology and SPSS correlation analysis were used to compare land use patterns and total nitrogen (TN) contents in the water body. Results showed that from 1990 to 2010, the areas of farm land and water body decreased continuously, while the areas of construction land and forest land increased. The status index(D_i)of land use pattern was in an order of constructed land>forest>grass land>farmland>water area. The increase in construction land was mainly come from cultivated land and water area, and the reduction of water area is mainly occupied by cultivated land. The area of cultivated land was significantly negatively correlated with the total nitrogen content of the water body (r= -0.959 *, P <0.05), indicating that the proportion of pollution derived from crop-faming was declining. There was no significant correlation between the areas of forest land and grassland and the TN content of the water body. There was a significant positive correlation between the area of construction land and the TN content of the water body (r = 0.929*, P <0.05), indicating that the construction land caused point source pollution.