南水北调中线核心水源区土壤氟空间变异特征与污染风险评价

Spatial variability and pollution risk assessment of soil fluorine in the core area of the Middle Route of the South-to-North Water Transfer Project

本文以生态环境脆弱的南水北调中线核心水源区为研究对象,运用GIS与地统计学相结合的方法以及污染风险评估模型,定量揭示了研究区土壤氟元素含量的空间变异特征、分布格局和污染风险等级。结果表明:(1)研究区土壤氟元素含量整体偏高,具有较明显的空间自相关性,表层土壤氟密度呈现从西向东、从南向中北部逐渐增加的趋势,并在中东部的南阳市淅川县仓房镇和丹江口市石鼓镇出现明显的单核聚集,与该区域地层岩性及成土母质特征对应;而土壤氟净增量状况则表明大部分地区氟含量都与后期人类活动有关;(2)氟环境污染程度具有较明显的区域分异性,根据地累计指数特性,表明除丹江口市习家店镇和嵩坪镇受成土母质等结构性因素制约外,其余地区多为人类活动造成的环境污染所致;(3)潜在生态风险程度表现为低风险区主要分布在研究区的西部和南部,中等风险区主要集中在中东部和北部。少量分布的高等风险区应引起重视,如淅川县盛湾镇东部、仓房镇西部以及丹江口市嵩坪镇和石鼓镇。研究结果旨在为土壤氟环境改善、库区饮用水安全保障等提供数据和技术支撑,同时也给当地土壤修复治理、确保优质清水北调提供决策依据。

In order to provide important data and technical support for improving local soil fluorine environment and ensuring water safety in reservoir area, it also provides decision-making basis for local soil remediation and ensure high-quality water diversion to the north, this study quantitatively analyzed the spatial distribution and pollution risk of soil fluorine in the core area of the Middle Route of the South-to-North Water Transfer Project with fragile ecological environment by using the methods of GIS and geostatistics and pollution risk assessment models. The results show that:(1) The soil fluorine content was on the high side and showed clear spatial autocorrelation in the study area. The fluorine density of topsoil increased gradually from west to east and south to middle north, and obviously peaked in Cangfang Town, Xichuan County and Shigu Town,Danjiangkou City in the central eastern part, which was corresponding to the characteristics of regional stratigraphic lithology and soil parent material. Combined with information on the net increment of soil fluorine, it was concluded that the fluorine content in most areas was related to human activities.(2) The degree of fluorine pollution showed obvious regional differentiation,which was mostly resulted from environmental pollution caused by human activities according to the characteristics of geoaccumulation index, except that Xijiadian Town and Songping Town of Danjiangkou City were restricted by structural factors such as soil parent material.(3) The degree of potential ecological risk indicates that level A was mainly distributed in the west and the south of the study area, and level B was concentrated in the central, eastern, and northern parts. The areas with the highest ecological risk were the east of Shengwan Town and the west of Cangfang Town in Xichuan County, Songping Town and Shigu Town in Danjiangkou City.