辽河保护区不同缓冲区尺度土地利用与水质的响应关系

Response relationship between land use and water quality at different buffer scales in Liaohe Conservation Area

为查明辽河保护区土地利用方式与水质的响应关系,将研究区地理空间数据云网站遥感影像数据和同期22个采样点实测作为数据源。实测数据包括水体营养盐类污染指标总氮(TN)、总磷(TP)、化学需氧量(COD)、溶解氧(DO)和氨氮(NH3-N)浓度和水体重金属类污染指标铜(Cu)、锌(Zn)、镍(Ni)、镉(Cd)、铬(Cr)、铅(Pb)和砷(As)浓度。通过GIS软件划出采样点周边250、500、750和1 000 m的圆形缓冲区,采用Spearman相关性分析和冗余分析(RDA)方法,分析不同空间尺度下各种土地利用类型与水质指标之间的关系。结果显示:(1)随着缓冲区面积的增加,土地利用类型更加丰富,水体营养盐类污染指标浓度以TN、TP的污染超标最严重,各项水体重金属类污染指标浓度均低于国家地表水Ⅰ类标准规定的限值。(2)在250、500、750和1000 m 4种圆形缓冲区中,250m缓冲区范围内土地利用方式对水质的解释率最高为60.8%。(3)在250 m缓冲区范围内,住宅用地与TN呈极显著的正相关;林地与TN、TP呈负相关,相关性系数分别为-0.459、-0.512;旱地与Cd呈显著正相关,相关性系数为0.685;水田与Cr呈极显著正相关,相关性系数为0.909。

To identify the response relationship between land use patterns and water quality in the Liaohe Conservation Area,the remote sensing image data of the geospatial data cloud website and the actual measurement of 22 sampling points in the same period were used as data sources.The measured data include total nitrogen(TN),total phosphorus(TP),chemical oxygen demand(COD),dissolved oxygen(DO),ammonia nitrogen(NH3-N),copper(Cu),zinc(Zn),nickel(Ni),cadmium(Cd),chromium(Cr),lead(Pb) and arsenic(As) concentrations.Circular buffers of 250,500,750 and 1 000 m around the sampling points are drawn by GIS software,and the relationship between various land use types and water quality indicators at different spatial scales was analyzed by the Spearman correlation analysis and redundancy analysis(RDA) methods.The results were as follows :(1) With the increase of buffer area,land use types become more abundant,the concentration of water nutrient salt pollution indicators was the most serious in terms of pollution exceeding the standard of TN and TP,and the concentration of metal pollution indicators of water were lower than the limit value stipulated by the national surface water class I standard.(2) Among the four circular buffer zones of 250,500,750 and 1 000 m,the highest interpretation rate of water quality by land use within 250m buffer zone was 60.8%.(3) The residential land was significantly positively correlated with TN in the 250 m buffer zone,while the woodland was negatively correlated with TN and TP with correlation coefficients of -0.459 and -0.512,respectively,the dryland was positively correlated with Cd with a correlation coefficient of 0.685,and the paddy field was significantly positively correlated with Cr with a correlation coefficient of 0.909.