Research On Representativeness Of Estuarine Sediment Sampling

Based on the update developmental trend of global geochemical mapping and asystematic comparison of the data from estuarine sediments of Xiangjiang river drainagebasin, Zishui river drainage basin and Yuanjiang river drainage basin in China with thedata of stream sediment from 1:200 000 China National Geochemical Mapping (RGNR)Program in each catchment basin, the author conducted a serious study on therepresentativeness of estuarine sediment as a sampling medium for global geochemicalmapping. The results set a technical example for "global geochemical mapping along theprincipal rivers of the world".From the geochemical theory of element concentration and transportation in supergeneenvironment, the geochemical characteristics of estuarine sediment were studied by thefield survey, indoor sample preparation and analysis, and data reduction.It can be concluded:1.In comparison of elemental average content among estuarine sediment of Xiangjiangriver drainage basin, Zishui river drainage basin and Yuanjiang river drainage basin inChina with the data from 1:200 000 China National Geochemical Mapping(RGNR )Program in each catchment basin, the set of estuarine sediment data among mostelements shows great coincidence with RGNR stream sediment and indicates thatestuarine sediment is an effective sampling medium which can reflect the averagegeochemical setting in drainage basin. Estuarine area is easy to be access and can controlthe large area of drainage basin (such as the area of Xiangjiang river drainage basin is94,660 km2, the area of Zishui river drainage basin is 28,142km2 and the area ofYuanjiang river drainage basin is 89,163 km2), at the same time the stream sediments iswidespread and easy to be collected, thus, using estuarine sediment as a samplingmedium for global geochemical mapping is suitable and feasible.2. The significant characteristic in the three river estuarine sediment is that Sn is enrichedin Xiangjiang river estuarine sediment, Sb is enriched in Zijiang river estuarine sedimentand Hg is enriched in Yuanjiang river estuarine sediment, which coincides with objectivegeology background in drainage basin which have huge mineral deposit: Sn-W, Sb, Hg.Therefore, estuarine sediment can clearly indicate the huge mineral deposit in drainagebasin.3. In comparison Sb content in estuarine sediment in Zishui river drainage basin, Sbcontent and its distribution pattern in Xiangjiang river estuarine sediment indicate thathuge Sb deposit could exist in Xiangjiang river drainage basin, even till now, nosignificant Sb deposit has been discovered in Xiangjiang river drainage basin.4. The distribution characteristic of estuarine sediment Cd in Xiangjiang river drainagebasin reveals that estuarine sediment can not only reflect the average geochemicalbackground of drainage basin but also record heavy metal pollution from human activity.