蒲河水质空间异质性特征及其对流域土地利用方式的响应

Spatial heterogeneity of water quality and its response to land use in Puhe River Basin

河流水质空间变化特征是流域生态系统健康评价的关键指标,是地形、地貌、气候、水文等自然环境因素及综合反映人类活动强度的土地利用方式对流域生态环境的复合作用,研究河流水质空间异质性特征及其对流域土地利用方式的响应关系对流域生态管理具有十分重要的指导意义,然而水质空间异质性特征及其对土地利用方式的响应机制研究仍不清楚。本文以辽河流域支流蒲河子流域为研究对象,利用GIS技术和地统计学方法,分析蒲河流域水质指标TN、TP、NH4+-N、CODcr、pH、DO和TDS空间变异特征,探讨流域不同土地利用方式对水质空间变化的影响。结果表明:蒲河流域水质指标NH4+-N、DO和TDS受结构性因素影响显著,表现出较强空间变异性;TP、CODcr和pH的空间异质性较弱,主要由随机性因素引起;TN受到结构性因素和随机性因素共同作用,表现出较弱空间变异特征;TN和NH4+-N含量与林地所占比例呈显著负相关,与耕地和建设用地所占比例呈显著正相关;pH和DO与水域面积和未利用地所占比例呈负相关;表明蒲河流域TN和NH4+-N空间异质性的主导因素为林地、耕地和建设用地等土地利用类型,pH和DO空间异质性的主导因素为水域和未利用地土地利用类型,该研究可为流域水环境管理提供数据支持。

Spatial variation of water quality factors, including TN, TP, NH4＋-N, CODcr, pH, DO and TDS, were analyzed by using GIS technique and geo-statistics method based on water sampling data collected in the Puhe River Basin from August to September 2012. Responses of water quality to land use changes were investigated. Results showed that the spatial distributions of NH4＋-N, DO and TDS were highly variable, and significantly affected by structural factorsincluding climate, topography, and hydrology. TP, CODcr and pH showed weak spatial variations, and were significantly affected by random factors such as human activity. TN showed a weak spatial variation and was jointly affected by structural and random factors. TN and NH4＋-N were negatively related to the proportion of forest lands and positively related to the proportions of agricultural lands and construction lands. Moreover, pH and DO were negatively related to the proportions of water area and unused land. Our results indicated that forest, agricultural lands and construction lands were the dominant factors driving the spatial heterogeneity of TN and NH4＋-N, and that water area and unused land were the dominant driving factor for the spatial variation of pH and DO. Results from this study provide support for environment management of river basin.