珠江三角洲地区土壤F分布及其与地氟病关系初探

Distribution characteristics of fluorine in soils of Zhujiang River delta in relation to endemic fluorosis

笔者结合珠江三角洲地区和中国土壤含F背景,研究了该区土壤F的含量特征、总体和典型区域的分布状况,对土壤类型、成土母质和土地利用类型等影响因素进行了分析,初步探讨了土壤F与地氟病的关系。结果表明,珠江三角洲地区浅层、深层土壤F平均含量分别为510mg/kg和529mg/kg,其中海(陆)相第四纪松散层区的三角洲沉积潜育性水稻土、三角洲盐渍水稻土、基水地的F含量最高。6760km2的浅层土壤F高背景区广泛分布于平原区,东莞、新会、珠海局部呈现污染区;深层土壤F高背景区5504km2,而污染区都集中在邻海的珠海市高栏、三灶两岛。土壤F的富集在沉积物区明显与第四纪海陆、陆海交互相沉积物有关,在基岩区明显和花岗岩类有关,人类影响较强的土壤和水稻土及其盐渍化有利于F富集。区内地氟病分布于从化、增城、东莞郊区、南海、新会和恩平,病区均位于高F的地层岩石区和土壤高F区。土壤F高背景区生长的农作物F含量存在超标,且病区农作物F超标率和超标倍数大于非病区,表明土壤中F的生物有效量比例较高,土壤F已向农产品中迁移和富集,危及到农产品质量。高F的地质环境是造成本区土壤及其农作物F含量高的主要原因,成为地氟病发生的致病因素。

The content and distribution characteristics of F in soils in the whole region and the typical areas of the Zhujiang River delta were studied by contrast with the F background of soils in the Zhujiang River delta and whole China. Soil types, parent rocks and land use types affecting the above situation were analyzed in this paper, and the relations between F content of soils and endemic fluorosis were discussed. The results show that the F average value of surface soils and deep soils in the Zhujiang River delta is respectively 510 mg/kg and 529 mg/ kg. The F content of the delta gleyed paddy soils, delta salinized paddy soils and irrigated land in Quaternary marine （continental） loose layer areas is the highest. The high F background areas of surface soils whose acreage is 6760 km2 are distributed in the central plain, the F pollution areas are spread in local areas of Dongguan, Xinhui and Zhuhai. The acreage of high F background areas of deep soils is 5504 km2, the F pollution areas are distributed in Gaolan island and Sanzhao island of Zhuhai City. The enrichment of F in soils is obviously related to Quaternary marine-terrigenous and terrestrial-marine facies sediments, and evidently has to do with granitoids in the bedrock. The soils influenced by human activity, paddy soils and their salinization seem to be beneficial to F enrichment . The endemic fluorosis in this region is distributed in Conghua, Zengcheng, suburbs of Dongguan, Naihai, Xinhui and Enping, where endemic areas are located in high F strata, rocks and soils. There exists excessive F in the crops growing in soils of high F background areas, and the F excessive rates and excessive times of crops in endemic areas are greater than those of crops in the non -endemic areas, suggesting that the proportion of bioavailable dose of F in soils in pollution areas is high, and F in soils has been migrated and enriched in agricultural products, which jeopardizes the quality of agricultural products. High F soils and crops in the study region caused by high F geological environment become factors responsible for endemic fluorosis.