【摘要】 珠江三角洲经过系统的1∶250000区域土壤地球化学调查发现,在三角洲冲积平原存在氟的高含量分布区。氟高含量区分布于第四纪海相和海陆交互相,从海相→海陆交互相→陆相含量逐渐降低,相同沉积相含量变化很小。从地表至深部,含量变化与沉积相关系密切,海陆交互相含量变化很小,而陆相含量变化较大。氟高含量区空间分布特征明显,控制因素显著,属于在沉积地质作用过程形成的。可能与珠江三角洲形成过程,西江、北江和东江带来大量含氟物质,加上海水富含氟,导致海相和海陆交互相沉积物氟含量较高而出现大面积的高含量区。更多还原

【Abstract】 The Pearl River Delta plain was covered by systemic regional soil geochemical survey with a sampling density at 1 to 2 samples per square kilometer and analytical density at 1 sample per 4 square kilometers for surface soils, and sampling and analysis density at 1 samples per 16 square kilometers for deep soils under 1.5 mete respectively.It is indicated that the abundant concentration of fluorine in the alluvial sediments of Bei River, Xi River and Dong River is obvious related to their geological background, and partly caused by mineral mining activities such as mining of the Fankou Pb-Zn deposit. It can be deduced that the abundance of fluorine in the soil of the Pearl River Delta have closely relatied to their sediment sources.The concentrations of fluorine in Quaternary marine sediments and transitional sediments are relatively higher than that of other geological settings. It seems that the concentrations of fluorine decreased in order of marine sediments, transitional sediments to continental sediments as presented by respective concentration of 679[FK(W+2mm。2mm][TPμ5宋体.tif,+1mm。1mm][FK)]g/g, 652[KG-*3][FK(W+2mm。2mm][TPμ5宋体.tif,+1mm。1mm][FK)]g/g and 336[KG-*3][FK(W+2mm。2mm][TPμ5宋体.tif,+1mm。1mm][FK)]g/g (Table 1). It means that the shallow sea sediment environment is apt to fluorine accumulation during transgression and regression.Quaternary marine sediments, and transitional sediments in Pearl River Delta are dominated by clay, fine-sandy clay and fine sands. Fluorine concentration changed from top to the bottom in different sediment environments. The normal concentration of fluorine varies from 760[KG-*3][FK(W+2mm。2mm][TPμ5宋体.tif,+1mm。1mm][FK)]g/g to 950[KG-*3][FK(W+2mm。2mm][TPμ5宋体.tif,+1mm。1mm][FK)]g/g (Table 4 and Fig.1) in the transitional sediments. The fluorine concentration in the plain of transitional sediments is normally of 400[KG-*3][FK(W+2mm。2mm][TPμ5宋体.tif,+1mm。1mm][FK)]g/g to 650[KG-*3][FK(W+2mm。2mm][TPμ5宋体.tif,+1mm。1mm][FK)]g/g in the top 2.5 meter layer (Table 5 and Fig.2). Continental material percentage increased near hilly, mountainous and mesa areas. The fluorine content is normally from 450[KG-*3][FK(W+2mm。2mm][TPμ5宋体.tif,+1mm。1mm][FK)]g/g to 800[KG-*3][FK(W+2mm。2mm][TPμ5宋体.tif,+1mm。1mm][FK)]g/g (Table 6 and Fig.3). The sediments has 230[KG-*3][FK(W+2mm。2mm][TPμ5宋体.tif,+1mm。1mm][FK)]g/g to 500[KG-*3][FK(W+2mm。2mm][TPμ5宋体.tif,+1mm。1mm][FK)]g/g of fluorine and vary greatly along sediment material with a variation of 20 percent in 50 percent samples (Table 7 and Fig.4) in continental sediments.The concentration of fluorine in ion exchangeable, water soluble, Fe-Mn oxides, organic compounds, and sulfides doesn’t vary greatly in Quaternary marine and continental sediments of the Pearl River Delta. It means that the enrichment of fluorine in soil is related to sediment source and sediment environment.The Pearl River Delta was developed through three cycles of transgression and regression. The whole dalta has the same development procedure. But there is still some difference from place to place on regional scale in the delta indicated by sediment source. The delta can be divided into four geographic portions as Bei River, Xi River, Dong River and Tan River alluvial fan. The high fluorine background is mainly located in the alluvial plains of Xi River, Bei River and Dong River with geological settings of Quaternary marine, and transitional sediments. Fluorine concentration decreases in order of marine, transitional, and continental sediments environments, and doesn’t have much change in the same environment. It doesn’t present any enrichment in urban, industrial and special agricultural production areas. The variation degree of fluorine concentration from surface to depth increased from transitional sediments to continental sediments. It showed that the fluorine concentration is controlled by sediment environment. Quaternary marine and transitional sediments have high fluorine. It is obvious that the fluorine in sediments of the Pearl River Delta更多还原