Organic matter mineralization in sediment of a coastal freshwater lake and response to salinization
Organic matter mineralization in sediment of a coastal freshwater lake and response to salinization
复制标题
DOI：
10.1016/j.gca.2006.03.012
复制
发表时间：
2006-06-01
影响因子：
5
通讯作者：
van den Berg, Gerard A.
中科院分区：
文献类型：
--
作者：
Canavan, Richard W.;Slomp, Caroline P.;van den Berg, Gerard A.
用多组分反应输运模型解释了哈林夫列特湖沉积物中的固相和孔隙水化学数据。这个淡水湖是由荷兰西南海岸的一条河流蓄水形成的，目前是恢复河口状况的目标。该模型被用来评估沉积物中的现代生物地球化学动力学，并预测底水盐化后有机碳矿化途径和相关氧化还原反应的可能变化。模型结果表明，氧化降解(55%)、反硝化(21%)和硫酸盐还原(17%)是目前沉积物表层有机碳降解的主要途径。与许多其他淡水沉积物不同，甲烷生成是一种相对较小的碳矿化途径(5%)，因为混合良好的底层水提供了大量的可溶性电子受体。尽管可抗坏血酸还原的Fe(III)矿物相存在于沉积物的上部30厘米处，但异化铁还原对整个沉积物新陈代谢的贡献可以忽略不计。敏感性分析表明，生物灌溉和生物扰动是控制有机碳降解在不同途径上分布的重要过程。模型模拟表明，硫酸盐还原将迅速抑制哈林夫利特海峡海水入侵时的甲烷生成，并可能导致沉积物中固态铁形态的显著变化。铁形态的变化将在20-100年的时间尺度上发生。(C)2006 Elsevier Inc.保留所有权利。
Solid phase and pore water chemical data collected in a sediment of the Haringvliet Lake are interpreted using a multi-component reactive transport model. This freshwater lake, which was formed as the result of a river impoundment along the southwestern coast of the Netherlands, is currently targeted for restoration of estuarine conditions. The model is used to assess the present-day biogeochemical dynamics in the sediment, and to forecast possible changes in organic carbon mineralization pathways and associated redox reactions upon salinization of the bottom waters. Model results indicate that oxic degradation (55%), denitrification (21%), and sulfate reduction (17%) are currently the main organic carbon degradation pathways in the upper 30 cm of sediment. Unlike in many other freshwater sediments, methanogenesis is a relatively minor carbon mineralization pathway (5%), because of significant supply of soluble electron acceptors from the well-mixed bottom waters. Although ascorbate-reducible Fe(III) mineral phases are present throughout the upper 30 cm of sediment, the contribution of dissimilatory iron reduction to overall sediment metabolism is negligible. Sensitivity analyses show that bioirrigation and bioturbation are important processes controlling the distribution of organic carbon degradation over the different pathways. Model simulations indicate that sulfate reduction would rapidly suppress methanogenesis upon seawater intrusion in the Haringvliet, and could lead to significant changes in the sediment's solid-state iron speciation. The changes in Fe speciation would take place on time-scales of 20-100 years. (c) 2006 Elsevier Inc. All rights reserved.