|关键词: 鄱阳湖 沉积物 剖面 Fe-Mn 迁移
|The migration of Fe and Mn and its relation to periodic variation of water level in Poyang Lake wetland soil
Qu Wenchuan, Yu Yuansheng
Lake Sediment and Environment Lab., Nanjing Institute of Geography & Limnology, CAS. Nanjing 210008
|Poyang Lake, a special freshwater lake, is an inflow-outflow lake with falling water level.and rich aquatic creature resources.The migratory behavior of Poyang Lake wetland soil elements is more remarkable than that of ordinary soil because of its periodic variation of water level.The typical elements, Fe and Mn, which are sensitive to oxidation-deduction control the geochemical circulation of some other trace elements.In this paper, the acidity (pH) and redox potential(Eh) of the wetland soil cores of Poyang Lake at different depths are observed in the spot.The distribution of the total content of elements, Fe and Mn, reduced Fe and Mn, organic matter etc.at different depths on the section is also studied.The results show that Fe and Mn are of special distribution pattern and migratory characteristics.Fe was only accumulated lightly on the water-land boundary layer, but Mn not only on the boundary layer, but also in deep layers.The distribution and migratory characteristics of reduced Fe and Mn which are controlled by the redox boundary layer occured in the vertical direction.Fe and Mn migrated in the horizontal direction was also found which was related to the change of water level.When tide is on the ebb, Fe and Mn migrate to the lake centre.Results in Dacha Lake, Sha Lake etc.around the Wucheng County showed the same conclusion.Finally we discussed the influence on the environment of Poyang Lake aera owing to the variation of water level caused by the Three-Gorge Project.After the building of the Three -Gorge Project, because discharge amount of the Yangtze River decreases in October caused by storing floodwater, Poyang Lake water level will descend significantly, and wetland of Poyang Lake will emerge earlier, resulting in, the change of soil characteristics.
|Key words: Poyang Lake sediment section Fe-Mn migration