RP1 Environmental Changes in Response to China's Economic Expansion
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(LIA-1117-554227) Characteristics of content distribution and species differentiation of rare earth elements in tideland water environment.

Tao, Liang¹, ¹ Chinese Academy of Sciences

ABSTRACT- Large quantities of rare earth elements (REEs) have been directly or indirectly entering water bodies due to mining activities and the applications in industry and agriculture in China during the past 30 years. Whether they could enter ocean and cause river and ocean pollution are press environmental issues. In this study, more than 40 water and sediment samples from sewage discharge channel and intertidal flat of Tianjin were collected. Speciation technique and ICP-MS analytical technology were used to determine the content of rare earth elements(REEs) in these samples. The results show that concentrations of dissolved REEs in water of the sewage discharge channels were very low. Concentrations of REEs in the sediments and suspended matter were lower than those in natural rivers, and concentrations of REEs in the suspended matter were much lower than those in the sediments. Distribution patterns of REEs in sediments and suspended matter were similar with light REE enrichment and positive Eu-anomaly. This distribution pattern was different from those of natural rivers. However, it was similar to those of local soils, implying that REEs in the channels came from the surrounding soils. The differences may have been caused by the large amount of organic pollutants in sewage. In addition, average concentrations of REEs in the filtered, unfiltered and interstitial water are 0.461g⋅L^-1, 4.98 g⋅L^-1 and 0.845 g⋅L^-1, respectively. Their distribution patterns are similar to those in inland natural rivers, but quite different from those in oceans. The average concentrations of REEs in sediments and suspended matters are 161.2 mg⋅L^-1 and 168.1 mg⋅L^-1, respectively, which are much lower than those in sediments of natural rivers but higher than those in sediments of the continental shelf of East China Sea. It is suggested that REEs in sediments and suspended matters of intertidal flat could have mainly originated from terrestrial soils and thus their transportation and transformation processes are similar with those in rivers, and different from those in continental shelves. Pollutants discharged into the Bohai Bay haven't caused significant effect on REEs in the intertidal flat of Tianjin yet.

Key words: rare earth elements, tideland water body, content, species