Fleck J A, Bossio D A, Fujii R
California State University Foundation, Sacramento, CA 95819, USA.
J Environ Qual. 2004 Mar-Apr;33(2):465-75. doi: 10.2134/jeq2004.4650.
A wetland restoration demonstration project examined the effects of a permanently flooded wetland on subsidence of peat soils. The project, started in 1997, was done on Twitchell Island, in the Sacramento-San Joaquin Delta of California. Conversion of agricultural land to a wetland has changed many of the biogeochemical processes controlling dissolved organic carbon (DOC) release from the peat soils, relative to the previous land use. Dissolved organic C in delta waters is a concern because it reacts with chlorine, added as a disinfectant in municipal drinking waters, to form carcinogenic disinfection byproducts (DBPs), including trihalomethanes (THMs) and haloacetic acids (HAAs). This study explores the effects of peat soil biogeochemistry on DOC and DBP release under agricultural and wetland management. Results indicate that organic matter source, extent of soil organic matter decomposition, and decomposition pathways all are factors in THM formation. The results show that historical management practices dominate the release of DOC and THM precursors. However, within-site differences indicate that recent management decisions can contribute to changes in DOC quality and THM precursor formation. Not all aromatic forms of carbon are highly reactive and certain environmental conditions produce the specific carbon structures that form THMs. Both HAA and THM precursors are elevated in the DOC released under wetland conditions. The findings of this study emphasize the need to further investigate the roles of organic matter sources, microbial decomposition pathways, and decomposition status of soil organic matter in the release of DOC and DBP precursors from delta soils under varying land-use practices.
一个湿地恢复示范项目研究了永久性水淹湿地对泥炭土沉降的影响。该项目于1997年启动，在加利福尼亚州萨克拉门托 - 圣华金河三角洲的特威切尔岛进行。相对于之前的土地利用方式，将农业用地转变为湿地改变了许多控制泥炭土中溶解有机碳（DOC）释放的生物地球化学过程。三角洲水域中的溶解有机碳令人担忧，因为它会与作为市政饮用水消毒剂添加的氯发生反应，形成致癌的消毒副产物（DBPs），包括三卤甲烷（THMs）和卤乙酸（HAAs）。本研究探讨了在农业和湿地管理下泥炭土生物地球化学对DOC和DBP释放的影响。结果表明，有机物来源、土壤有机质分解程度和分解途径都是三卤甲烷形成的因素。结果表明，历史管理实践主导了DOC和三卤甲烷前体的释放。然而，现场差异表明，近期的管理决策可能会导致DOC质量和三卤甲烷前体形成的变化。并非所有芳香形式的碳都具有高反应性，特定的环境条件会产生形成三卤甲烷的特定碳结构。在湿地条件下释放的DOC中，卤乙酸和三卤甲烷前体均有所升高。本研究结果强调需要进一步研究在不同土地利用方式下，有机物来源、微生物分解途径以及土壤有机质分解状态在三角洲土壤DOC和DBP前体释放中的作用。
