【摘要】 铁氧化物在全球土壤（沉积物）有机碳（Organic Carbon,OC）存储中具有重要作用。红树林湿地同时具有陆源与海源输入，为活性铁氧化物（Fe_R）对OC的保存提供了独特的生境。然而红树林表层沉积物中Fe_R对OC保存过程中的影响因素以及Fe_R对OC组分的选择性尚不明确。本研究选择广西大风江入海口和茅尾海周围受到潮汐与河流影响的天然红树林生境中的表层沉积物，研究沉积物中铁结合有机碳（Fe-OC）含量以及组分的变化。结果表明，大风江入海口与茅尾海表层沉积物中Fe-OC平均含量分别为0.16%±0.07%与0.17%±0.07%，在总有机碳（TOC）中所占比例(f_Fe-OC)分别为16.2%±5.04%与10.9%±5.63%，主要保存方式为吸附。Fe_R对OC的保存受到沉积物粒度、Fe_R含量与形态以及TOC来源与组分的影响。TOC、Fe_R与Fe-OC主要分布在粒度较小的沉积物组分中。表层沉积物中铁的存在形式以Fe₃₊为主，占总铁的87.42%，在高盐度沉积物中相对更高。Fe_R会选择性保存结合δ₁₃C值（稳定性碳同位素自然丰度）偏正的OC与芳香族OC。与茅尾海相比较，大风江入海口表层沉积物Fe-OC中类蛋白荧光组分占总荧光组分的比例更高。类蛋白荧光组分占比随Fe-OC∶Fe摩尔比升高而升高。本研究有助于明确广西红树林表层沉积物中Fe_R对OC的选择性保存机制，加深对陆海界面沉积物中OC的保存过程的了解。更多还原

【Abstract】 Iron oxides play a significant role in the global soil （sediment） organic carbon （OC） storage.Mangrove wetlands,receiving both terrestrial and marine inputs,provide a unique habitat for the preservation of organic carbon by reactive iron oxides （Fe_R）.However,the impact of Fe_R in the surface sediments of mangroves on the preservation process of OC,as well as the selectivity of Fe_R towards different OC components,is still unclear.The surface sediments in the present work was collected in the natural mangrove areas around the estuaries of the Dafeng River and Maowei Sea in Guangxi,which are highly influenced by tides and rivers.The research was focused on the changes in the content and composition of iron-bound organic carbon （Fe-OC） in sediments.The results indicated that the average content of Fe-OC in surface sediments in the estuaries of Dafeng River and Maowei Sea was 0.16%±0.07%and 0.17%±0.07%,respectively.These values represented 16.2±5.04%and 10.9±5.63%of the total organic carbon （TOC） content in the respective sediments,which were primarily preserved through adsorption.Furthermore,the preservation of OC by Fe_R was influenced by the sediment particle size,the content and form of Fe_R,and the source and composition of TOC.TOC,Fe_R and Fe-OC were mainly distributed in the smaller grain size sediment fractions.The predominant form of iron in surface sediments was Fe3⁺,accounting for 87.42%of the total iron,and was relatively higher in high salinity sediments.Fe R selectively preserved OC with higher δ¹³C （stable carbon isotope natural abundance） and aromatic OC.Compared with the Maowei Sea,the proportion of protein-like fluorescent components in Fe-OC of surface sediments from the Dafeng River estuary was higher and the proportion of protein-like fluorescent components increased as the molar ratio of Fe-OC∶Fe increased.This study helps to clarify the selective preservation mechanism of OC by Fe_R in mangrove surface sediments in Guangxi,and deepen our understanding of the preservation process of OC in land-sea interface sediments.更多还原