Sandy seepage faces as bioactive nitrate reactors:Biogeochemistry,microbial ecology and metagenomics  

作　　者：Shan Jiang Jie Jin Yongjun Wei Ying Wu Yixue Zhang Carlos Rocha Juan Severino Pino Ibánhez Guosen Zhang Jing Zhang 

机构地区：[1]State Key Laboratory of Estuarine and Coastal Research,East China Normal University,Shanghai 200241,China [2]School of Pharmaceutical Sciences,Key Laboratory of State Ministry of Education,Key Laboratory of Henan Province for Drug Quality Control and Evaluation,Collaborative Innovation Center of New Drug Research and Safety Evaluation,Zhengzhou University,Zhengzhou 450001,Henan,China [3]Biogeochemistry Research Group,School of Natural Sciences,Trinity College Dublin,Dublin 2,Ireland [4]Instituto de Investigacións Mariñas,Consejo Superior de Investigaciones Científicas(IIM-CSIC),Eduardo Cabello 6,36208 Vigo,Spain [5]School of Oceanography,Shanghai Jiao Tong University,Shanghai 200040,China

出　　处：《Geoscience Frontiers》2023年第3期74-89,共16页地学前缘（英文版）

基　　金：supported by National Natural Science Foundation of China(Nos.42111530026 and 41706081);Scientific Research Foundation of SKLEC(2017RCDW04)。

摘　　要：Subterranean estuaries are highly dynamic in processing dissolved inorganic nitrogen(DIN).Here we investigate DIN turnover in surface sediments(0–20 cm depth)at the higher,medium and lower intertidal of a seepage face,i.e.,the outer “mouth”of the subterranean estuary,during four consecutive seasons in Sanggou Bay,China.Throughout the studied period,ammonium(NH_(4)^(+))and nitrite(NO_(2)^(-))concentrations in the sampled porewaters did not vary significantly with depth or season.In contrast,peaks in porewater nitrate(NO_(3)^(-))concentration and decreases in δ^(15)N-NO_(3)^(-) and δ^(18)O-NO_(3)^(-) were observed in the 15–20 cm depth(bottom)sediment,particularly during summer and autumn.Coupled with NO_(3)^(-) production,the sediment total nitrogen was also markedly peaking in the bottom layer of the studied seepage face.Together with abundant heterotrophic microbes in the sediment,this NO_(3)^(-) accumulation was linked to a reaction chain including organic matter decomposition,ammonification and nitrification.During winter,porewater enrichment in total nitrogen occurred closer to the surface of the seepage face but triggered also active NO_(3)^(-) production.This pattern reinforced the importance of pelagic organic matter supply on NO_(3)^(-) production.In the shallower depths of the seepage face(<12 cm),active net NO3removal occurred except in winter.The isotopic fractionation(δ^(15)N-NO_(3)^(-) and δ^(18)O-NO_(3)^(-) and metagenomic results revealed denitrification as the main pathway for NO_(3)^(-) reduction.Biological assimilation from benthic primary producers may also consume a fraction of NO_(3)^(-) at the sediment water interface.Both NO_(3)^(-) production and removal significantly varied in magnitude with season(13.6 to 6.2 nmol cm^(-3)h^(-1)).Substrate supply was the key driver for nitrate cycling,as evidenced by the high NO3production rate in spring by comparison to autumn.The highest NO_(3)^(-) turnover rates were found in summer,suggesting the combined influence of advection rates and s

关 键 词：Benthic microbiota NITRATE Stable isotopes Subterranean estuary Denitrification 

分 类 号：X523[环境科学与工程—环境工程] P641[天文地球—地质矿产勘探]