Distributions Of Total Dissolved Inorganic Arsenic In Partial Rivers, Estuaries, And Coastsal Waters Of China

Arsenic is a metalloid element which occurs ubiquitously in nature. The biogeochemical cycles of arsenic in the aquatic environment have captured the interest of geochemists due to large anthropogenic input with the quick development of industry and agriculture.The investigations were carried out in two major regions, one was the Changjiang Drainage Basin, the coastal area adjacent to the Changjiang and the East China Sea Shelf, the other was the primary Rivers estuaries in Hainan (Wanquan River, Wenchang/Wenjiao River), the eastern coastal areas in Hainan and the groundwater ecosystem. The distributions and seasonal variations of the concentration of total dissolved inorganic arsenic (TDIAs) in the study areas and the affecting factors were discussed in this dissertation. Some important conclusions were listed below:1. In January of 2008, field observations were carried out in the Changjiang River, average concentrations of TDIAs were 65.1±18.8nmol·L-1 with range of 31.8~130.2 nmol·L. Concentration of TDIAs in the bottom water showed a similar trend as that in the surface water. The concentrations of TDIAs have little difference from upper to lower reaches.2. In April of 2008, the field obveration was carried out in the Changjiang estuary. The Concentrations of TDIAs varied from 6.2 to 40.5 nmol·L with an average of 17.1±6.2nmol·L-1. The distributions of TDIAs were influenced by the Changjiang diluted water and Taiwan Current Warm Water. The horizontal distribution of TDIAs showed a trend of gradually decreasing with the distance off the Changjiang estuary.3. In May of 2007 and 2008, concentrations of TDIAs in the coastal area of Zhejiang and Fujian were determined, which varied from 13.1 to 23.9 nmol?L-1 and from 10.1 to 20.3 nmol?L-1, respectively. Distributions of TDIAs in the surface water were primarily influenced by the Changjiang diluted waters and Zhejiang and Fujian coastal flow, showing a trend of gradually decreasing from seashore to offsea. In the bottom water, transport of the Changjiang River, together with the re-suspension of percipitation and decomposition, gave rise to elevation of concentrations of TDIAs. In the offsea area, distributions of concentrations of TDIAs also been affected by the Taiwan current warm water and Kuroshio Water.In May of 2008, observations of TDIAs were carried out in Zhejiang Pronvince The Concentrations of TDIAs ranged between 9.9 and 52.1 nmol?L-1, with exception of the Jiaojiang River(251.92 nmol?L-1) and the Feiyunjiang River(52.1 nmol?L-1). Overall, concentrations of TDIAs in seven major rivers were lower than those in the Changjiang River.4. The field observations were undertaken on the shelf of East China Sea (ECS) in November of 2006 and February of 2007. Averaged Concentrations of TDIAs were 17.3±2.7 nmol?L-1 and 18.4±2.4 nmol?L-1, respectively, showing a significantly seasonal variationas. The distributions of TDIAs were controlled by various water masses in ECS, including Changjiang Diluted Water (CDW), Kuroshio Water (KW), and Shelf Mixed Water (SMW). Concentrations of TDIAs decreased gradually from seashore towars the shelf region and the higher concentrations of TDIAs appeared in the coastal area and shelf edge of ECS. The water was well mixed in the coastal region and stratified at the near bottom of the Shelf break of the ECS. Incursion of KW was more intensity in the winter than in the autumn. Compared with other areas in the world, the concentration of dissolved inorganic arsenic on the ECS shelf remained at the natural level.5. The field observations were undertaken in the Wanquan River, Wenchang/Wenjiao River, the estuaries and the eastern coastal area in Hainan in 2006, 2007 and 2008. The results showed significantly seasonal variations in this area. In winter, the average concentrations of TDIAs in the Wanquan River and Wenchang/Wenjiao River were averaged 5.0±2.7 nmol?L-1 and 5.9±4.2 nmol?L-1, respectively. While in summer, concentration averaged 7.5±3.7 nmol?L-1 and 10.0±4.1 nmol?L-1, respectively. The bihavior of TDIAs is conservative in Wanquan and Wenchang/Wenjiao estuaries.Concentrations of TDIAs in the eastern coastal area of Hainan were higher than rivers and averaged 17.0±1.3 nmol?L-1 and 16.0±1.7 nmol?L-1 ,respectively in 2007 and 2008. The distrbutions of TDIAs were controlled by Nanhai Warm Current, with obvious Stratification from surface to bottom.