崇明东滩盐沼表层沉积物有机碳空间分布特征及其来源示踪研究

沉积物有机碳空间分布特征及其来源是盐沼碳循环研究的一个关键问题。该研究分析了长江口崇明东滩盐沼表层沉积物样品总有机碳(TOC)、总氮(TN)和稳定碳同位素(δ13C)等参数。研究表明:东滩表层沉积物TOC和TN的平均值分别为7. 70±3. 74和0. 74±0. 32 g/kg,两者均表现为自北向南减少的分布趋势。沉积物δ13C平均值为-25. 05±1. 21‰,三元混合模型模拟计算结果表明东滩沉积物有机碳主要来源于悬浮颗粒物(43. 53±22. 44%)和植被(43. 29±24. 82%),底栖微藻贡献率较低(13. 20±8. 40%)。东滩北部沉积物表现为高悬沙贡献-低植被贡献-高有机碳含量特征,中南部表现高植被贡献-低悬沙贡献-低有机碳含量的特点。

Spatial Distribution Characteristics and Source Tracing of Organic Carbon in Surface Sediments of Salt Marsh in Dongtan of Chongming

The spatial distribution characteristics and sources of organic carbon in sediments are a key issue in the study of salt marsh carbon cycling. The study analyzed the parameters of total organic carbon (TOC), total nitrogen (TN) and stable carbon isotope (δ13C) in the surface sediment samples of the Chongming Dongtan salt marsh in the Yangtze River estuary. The results showed that the average TOC and TN in surface sediments in Dongtan were 7.70±3.74 g/kg and 0.74±0.32 g/kg respectively. Both showed a decreasing trend from the northern part of the salt marsh to the south of the salt marsh in content. The average value of sediment δ13C was-25.05±1.21‰. The simulation results of the three end-member mixing equations showed that the organic carbon in Dongtan sediments was mainly derived from suspended particles (43.53±22.44%) and vegetation (43.29±24.82%). The contribution rate of microalgae is lower (13.20±8.40%). The sediments in the northern part of Dongtan are characterized by high organic carbon content, in which the contribution of suspended particulate matter is high and the contribution of vegetation is low. In the middle and south, the content of organic carbon is low, the contribution of suspended particulates is low and the contribution of vegetation is high.