三江平原湿地沉积有机碳密度和碳储量变异分析

Spatial Variability of the Density of Organic Carbon and Carbon Storage in the Sediment Profiles of Wetlands in Sanjiang Plain,Northeast China

论文研究了东北三江平原3类典型湿地共16个沉积物剖面有机碳的分布特征。结果表明,沼泽化草甸、腐殖质沼泽和泥炭沼泽的储碳层厚度分别为11～29、18～58和70～130cm;其有机碳含量(单个剖面平均)分别为29～75、124～348和187～389g/kg(干物质计);有机碳密度(单个剖面平均)分别为31～48、35～59和49～94kg/m3。3类湿地淀积层的有机碳含量和密度都很低且较稳定。由于有机碳含量的差异,不仅3类湿地之间而且同一类型湿地的不同剖面间有机碳密度的差异也十分明显。储碳层厚度及有机碳密度的空间变异性是导致湿地有机碳储量估算不确定性的主要原因。根据研究结果估算,沼泽化草甸、腐殖质沼泽和泥炭沼泽储碳层单位面积碳储量分别约为8×103、18×103和72×103t/km2,其变异系数分别约为40%、49%和34%;“储碳层+1m淀积层”的单位面积碳储量分别约为17×103、27×103和83×103t/km2,其变异系数分别约为16%、39%和27%。表明以“储碳层+1m淀积层”深度来估算碳储量能较合理地反映湿地沉积物有机碳的蓄积特征。结果还表明,以1m作为统计深度将在很大程度上低估湿地的碳储量。

Wetland is recognized as a large reservoir of organic carbon(C)in terrestrial ecosystems.In this study,the density and variations of organic C in the sediment profiles(totally 16) of the 3 types of wetlands in Sanjiang Plain,Northeast China was investigated.Results demonstrated that the depth of the organic horizon varied in the range of 11～29,18～58 and 70～130 cm;the content of organic C in the horizon in the range of 29～75,124～348 and 187～389g/kg (dry matter);and the density of organic C in the range of 31～48,35～59 and 49～94kg/m3 for marshy meadow,humus marsh,and peat fen,respectively.However,the content and density of organic C in the mineral-illuvial horizon of all the 3 types of wetlands were relatively low and stable.Due to the variations in the content of organic C,a big variation in the density of organic C also occurred not only in the sediment profiles of different types of wetlands but also the same type of the wetland.This variability,together with that in the depth of the organic horizon,resulted mainly in uncer-tainties in the estimates of organic C storage in wetlands.Based on data obtained,it was estimated that the amount of organic C storage per unit area was 8×103,18×103 and 72×103t/km2(with variation coefficients of 40%,49% and 34%) in the organic horizon,and 17×103,27×103 and 83×103t/km2(with variation coefficients of 16%,49% and 30%)in the organic horizon plus 1 m mineral-illuvial horizon of the marshy meadow,humus marsh,and peat fen,respectively.It also suggested that the organic C storage would be greatly underestimated if we only take 1 m as the standard depth in the estimating method for organic C storage.