珠江三角洲经济区农业地质与生态地球化学调查成果综述

2005年中国地质调查局与广东省人民政府联合开展珠江三角洲经济区农业地质与生态地球化学调查项目。通过开展多目标区域地球化学调查、区域生态地球化学评价、局部生态地球化学评价和总体综合评价,系统完成了珠江三角洲经济区47 954 km~2(包括10 m水深以浅的近岸海域)的生态地球化学调查与评价。按照双层网格化方法系统采集了陆域土壤、近岸海域和珠江水系主要河流沉积物表层和深层样品,测试了71项元素和指标,建立了珠江三角洲经济区土壤、沉积物地球化学背景值和基准值,全面查明了珠江三角洲经济区土壤环境质量状况。定量计算了镉、铅、汞等主要异常元素经河流、成土过程等自然来源和大气干湿沉降、施肥、灌溉、使用农药等人为来源贡献量,阐明了其迁移转化途径及生态安全性。项目紧密结合本地区特点,在国内首次开展了三角洲形成演化过程地球化学研究、区域辐射环境质量评价、酸雨对土壤质量影响的模拟实验、土壤环境质量地方标准研究与制订等工作。

Main Research Achievements of Agro-geological and Eco-geochemical Research in Pearl River Delta Economic Zone,Guangdong Province,China

Soil heavy metal pollution is one of the main environmental problems in Pearl River Delta Economic Zone. It directly threatens the stability of regional ecosystem and food safety, and has profound influences on economic sustainability, especially for sustainable agriculture and people′s health. Consequently, soil environment quality and food safety in this region have received extensive attention from all around China. Based on multi-purpose regional geochemical survey, regional eco-geochemical assessment, local eco-geochemical assessment and comprehensive appraisal, the eco-geochemical survey and assessment in Pearl River Delta Economic Zone of 47 954 km² (including the area of 10 m depth in shallow inshore waters) was completed. Samples of soil, sediments of intertidal and major rivers in the region were collected in accordance with the two-layer grid method. It is the first time to study the geochemical characteristics of the Pearl River Delta region, and totally 71 elements and indicators for soils and sediments were determined. On the basis of the regional survey, the samples of rock, soil, sediment, dust, water, biology, human hair and other types of media samples in significant zone were systemic collected. The composition, distribution characteristics, sources, impact mechanisms and ecological security, migration and transformation process of toxic elements and nutrition elements in significant zone were investigated through case research and general analysis. According to the characteristics of the area, we firstly carried out the study of geochemical character of delta formation evolution and formulation of environmental quality standards for soils in the Pearl River Delta Area.