SCIENTIA GEOGRAPHICA SINICA ›› 2014, Vol. 34 ›› Issue (3): 358-364.doi: 10.13249/j.cnki.sgs.2014.03.358

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Nutrient Variation in Water and Sediments of Ditch Wetlands and Their Effects on Environment in Sanjiang Plain, China

Min XI1(), Fan-long KONG1, Xian-guo LU2, Ming JIANG2, Yue LI1   

  1. 1.College of Chemical and Environmental Engineering, Qingdao University, Qingdao, Shandong 266071, China
    2.Northeast Institute of Geography and Agricultural Ecology, Chinese Academy of Sciences, Changchun, Jilin 130012, China)
  • Received:2013-03-21 Revised:2013-05-10 Online:2014-03-10 Published:2013-08-16

Abstract:

The effect of land use, vegetation growth and flooded condition on spatial-temporal variation of nutrient and eco-environmental effects in two typical ditch systems of Sanjiang Plain, Northeast China, was analyzed through in situ sampling of surface waters and sediments. The results showed that the nutrition of ditch systems mainly came from the farmland and the wetlands in the surrounding area. And the key factors influencing the change of nutrients in sediments and ditch systems include land use, vegetation growth, flooding condition and the degree of blocks. Ditch systems accommodate and purify the runoff from the surrounding farmland and wetland, and reduce the risk of the eutrophication of down stream water body. However, the accumulation of nutrients in ditch systems will bring potential threats to the stability of wetland ecosystem. The land reclamation leads to the reduction of soil DOC storage and the blocking of the ditches can effectively reduce the transport and export of soil DOC. The reclamation from wetland to dry land is beneficial to the accumulation of sediment DOC in ditches, but at the same time, it reduces the soil DOC storage. Therefore, the content of sediment DOC was highest and the ditch water DOC concentrations were lowest in the dry land ditches. The reclamation of Sanjiang Plain wetland and the utilization of large amounts fertilizers made the concentrations of TN and TP in dry land ditch higher than that in the wetland and paddy field ditches. The difference of vegetation growth status made the concentrations of TN in wetland ditch water higher than that in paddy field ditch. Nitrogen and phosphorus accumulated in the plant would be decomposed and released in spring, which made N and P in water increased obviously. The TOC and TN content in the sediments of the ditch systems increased with the decay decomposition of plants in autumn and winter. There is a strong correlation between the flooding conditions of the ditch system and the TOC and TN content in the sediments. The flooding conditions have an indirect impact on the TOC and TN content through influencing the mineralization process of the organic matter and the rate of decomposition or transformation of the total nitrogen. In addition, as a result of the long-term accumulation of nutrients in ditch systems, the concentration of N/P in wetland waters decreases, which will consequently bring potential threats to the stability of the wetland ecosystem.

Key words: Ditch systems, nutrient characteristics, eco-environmental effects, Sanjiang Plain

CLC Number: 

  • X144