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红树林湿地沉积物硫酸盐-甲烷界面分布特征及其影响因素研究
曹超,姜德刚,潘翔,陈庆辉,吴剑,刘珉璐,宋志晓,刘贞文
0
(国家海洋局第三海洋研究所,福建 厦门 361005;国家海洋局海岛研究中心,福建 平潭 350400)
摘要:
利用孔隙水化学和稳定同位素化学等方法分析珠江口红树林湿地沉积层孔隙水硫酸根(SO2-4)、游离甲烷气体(CH4)、总溶解无机碳(DIC)以及 δ13CDIC 的垂直剖面分布特征.结果显示,孔隙水SO2-4浓度自表至底呈线性梯度减小,至硫酸盐-甲烷界面(SMI)附近,硫酸盐几乎全部消耗,而CH4浓度急剧增大,KC1、KC3、KC4、K17和K10等5个站位SMI深度分别为20、50、70、80、50 cm,SMI深度由红树林湿地林间向光滩逐渐增大.同时,孔隙水DIC浓度在该深度明显升高,沉积物发生强烈的甲烷厌氧氧化(AOM)作用.在AOM过程中,由于12CH4 氧化速率较13CH4 快,故引起沉积物孔隙水 δ13CDIC偏轻.沉积层中的有机质含量及其活性高低是制约沉积物SMI分布深浅的关键因素,高含量的活性有机质可加速孔隙水SO2-4 再矿化过程的消耗,使得通过AOM作用的SO2-4 消耗通量相应增大.在微生物作用下,部分活性有机质被大量消耗,致使进入沉积物SO2-4 还原带的活性有机质数量相应减少,从而引起部分SO2-4 转为与CH4 发生反应促进AOM作用.
关键词:  海洋化学  孔隙水  硫酸盐 甲烷界面  甲烷厌氧氧化  红树林湿地
DOI:10.3969/J.ISSN.2095-4972.2018.02.007
基金项目:国家自然科学基金资助项目(41406059,41276058);国家海洋公益性科研专项资助项目(201505012-5);福建省自然科学基金资助项目(2016J01190);海洋地质国家重点实验室开放基金资助项目(MGK1604)
Study on distribution of sulfate and methane interface in mangrove wetland sediments and its influencing factors
CAO Chao,JIANG De-gang,PAN Xiang,CHEN Qing-hui,WU Jiang,LIU Min-lu,SONG Zhi-xiao,LIU Zhen-wen
(Third Institute of Oceanography, SOA, Xiamen 361005, China;Island Research Center, SOA, Pingtan 350400, China)
Abstract:
The vertical distribution of sulfate, free methane, dissolved inorganic carbon and δ13CDIC in pore water of the sediments in the Pearl River Estuary was analyzed used methods of pore water chemistry and stable isotope chemistry. The results showed that concentration of pore water sulfate decreased linearly from the top to the bottom. Near the sulfate and methane interface, almost all sulfates were consumed and the concentration of methane increased sharply. The sulfate and methane interface of KC1, KC3, KC4, K17 and K10 were at 20 cm, 50 cm, 70 cm, 80 cm and 50 cm, respectively. The depth of SMI increased gradually from the mangrove area to the bare flat. At the same time, the concentration of DIC increased significantly in the pore water. The intensive methane anaerobic oxidation occurred in the sediments. During the AOM process, due to faster 12CH4 oxidation rate than 13CH4, it lighted δ13CDIC in sediments pore water. The results showed that the content of organic matter and its activity in the sediments were the key factors controlling the depth of SMI. High content of active organic matter could accelerate the remineralization process of pore water sulfate and increased correspondingly the sulfate flux through AOM. Under the action of microorganisms, parts of labile organic matter (mainly algaderived) were consumed and the amount of organic matter entering the base of sulfate reduction zone reduced, which promote the AOM action due to reactions of partial sulfate with methane.
Key words:  marine chemistry  pore water  sulfate and methane interface  anaerobic oxidation of methane  mangrove wetland

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