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    黄河三角洲滨海湿地演化过程中的碳埋藏效率及其控制因素

    Accretion rate and controlling factors of carbon and nutrients during coastal wetland evolution in Yellow River Delta

    • 摘要: 2007年在黄河三角洲布设了一口浅钻ZK4,孔深28.3 m,对获取的岩心样品进行了详细的沉积学观测及含水量、有机碳、总碳和营养成分的实验室分析测试。通过ZK4孔的地层分析,将其划分为7种沉积环境,揭示了滨海湿地地质演化过程。并利用AMS14C测年方法,结合黄河改道的历史记录,运用历史地理学和沉积地质学综合分析的方法对黄河三角洲沉积环境进行了年代划分,并计算了黄河三角洲不同沉积环境沉积物的沉积速率和碳的加积速率。结果表明:总碳和有机碳与除硫和磷元素以外的各营养成分都呈良好的线性相关;碳、氮、磷的加积速率与沉积物的沉积速率呈极显著正相关关系(R>0.89,p<0.01),沉积物的沉积速率是碳、氮、磷的加积速率的主控因素;虽然现代黄河三角洲沉积物有机碳浓度较低(<1%),但由于沉积物的高沉积速率,现代黄河三角洲沉积物有机碳的平均加积速率达到2878.23 g/(m2·a),远高于世界其他高有机碳浓度的湿地,因此是很好的碳汇地质体。

       

      Abstract: Core ZK4 with a shallow depth of 28.3 m was drilled in the Yellow River Delta in 2007. Samples from the core were used in the laboratory to make detailed sedimentological observations and perform analysis of water content, organic carbon (Corg), total carbon (TC), and nutrient compositions. According to the stratigraphic analyses of core ZK1, seven sedimentary environments were recognized, and the historical evolutions of coastal wetlands were revealed. Chronologies, sedimentation rates and carbon accretion rates of the environments were revealed from AMS14C dating method, historical records of the Yellow River diversions, and comprehensive analyses by means of historic geography and sedimentary geology. The results show that total carbons, organic carbons and nutrients (except for element S) are all in good linear correlations, the accretion rates of Corg, TC, N and P have very significantly positive correlations with sedimentation rates shown as R>0.89, p<0.01, and the sedimentation rates are the main factor controlling accretion rates of Corg, TC, N and P. Although Corg concentrations are low (<1%) in the modern Yellow River Delta sediments, the high sedimentation rates have made the average accretion rate of Corg in the sediments come up to 2878.23 g/(m2·a), much higher than the values in other high-Corg wetlands in the world, and thus the modern Yellow River Delta can be considered to be a very good carbon sink due to its high sedimentation rate.

       

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