长江口滩涂湿地景观变化对N、P营养物质净化潜力的影响

    Impacts of Changes in Landscape of Tidal Wetlands on Potential of the Wetlands Purifying Nitrogen and Phosphorus in Water at the Yangtze Estuarine

    • 摘要: 基于长江口4期遥感影像及野外考察资料,并结合国内外文献报道的该研究区及其周边植被、气候等条件类似地区湿地对水体中N、P营养物质的去除潜力,估算了长江口滩涂湿地去除N、P营养物质的潜力及其变化。结果表明:随着围垦导致的陆域面积、湿地总面积扩大以及湿地景观类型的变化,长江口滩涂湿地年N去除潜力由1980年的710.53~4 039.37 t增加到2010年的5 137.68~9 305.83 t,P去除潜力由1980年的64.62~408.55 t增加到2010年的886.45~1 228.08 t。30 a来堤外3种典型盐沼植被对N的去除潜力约增加800~1 100 t,对P的去除潜力约增加60~70 t,但占总去除潜力的比例却分别下降约44~71和62~84百分点。其中,藨草群落和芦苇群落对N、P的出除潜力贡献均呈不断减少趋势,相反,外来物种互花米草对N、P的出除潜力贡献分别由0%和0%增加到17%~24%和10%~19%。湿地净化潜力评估可为长江口地区水质改善、水源与湿地保护提供科学依据。

       

      Abstract: Based on field investigations in and remote-sensing images of the Yangtze Estuary in 1980, 1990, 2000 and 2010, and taking references of reports from international and domestic literature about potentials of wetlands, similar to those in the Yangtze Estuary in vegetation and meteorology, of removing nutrient substances, such as N and P, in the waterbody, the potentials of the tidal wetlands in the Yangtze Estuary were assessed and their changes predicted. Results show that along with the expansion of land and total wetland and changes in wetland landscape triggered by poldering, N removing potential of the tidal wetlands at the Yangtze Estuarine increased from 710.53~4 039.37 t in 1980 to 5 137.68-9 305.83 t in 2010, and P removing potential did from 64.62~408.55 t in 1980 to 886.45-1 228.08 t in 2010. In the past 30 years, N removal potential of the three dominant salt marsh vegetation outside the dike increased by 800-1 100 t, and P removal potential did by about 60-70 t. But their contribution to the total N and P removal dropped by 44-71 and 62-84 percentage point, respectively, especially Scirpus and Phragmites communities, whose contributions to the total N and P removal followed a steady downward trend. In contrast, the contribution from Spartina alterniflora, an exotic species, increased from 0% to 0% to 17%-24% and 10%-19%, respectively. The assessment may provide some scientific basis for improving water quality and protecting water sources and wetlands in the Yangtze Eestuary.

       

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