Sedimentary nitrogen dynamics in a coastal reef area with relatively high nitrogen concentration  

作　　者：Zhiming Ning Ronglin Xia Bin Yang Cao Fang Wei Jiang Guodong Song 

机构地区：[1]Guangxi Laboratory on the Study of Coral Reefs in the South China Sea,School of Marine Sciences,Guangxi University,Nanning 530004,China [2]Guangxi Key Laboratory of Marine Environmental Change and Disaster in Beibu Gulf,Beibu Gulf University,Qinzhou 535011,China [3]Key Laboratory of Marine Chemistry Theory and Technology of Ministry of Education,Ocean University of China,Qingdao 266100,China

出　　处：《Acta Oceanologica Sinica》2023年第4期33-40,共8页海洋学报（英文版）

基　　金：The Guangxi Natural Science Foundation under contract Nos 2019GXNSFAA185001 and 2019GXNSFAA185022;the National Natural Science Foundation of China under contract Nos 41976059 and 42166002.

摘　　要：The migration and transformation of nitrogen(N)in sediments play an important role in regulating the N concentration and nutrient structures in shallow seas.However,studies of sedimentary N dynamics are rarely focused on carbonate sediments,although these account for about 40%of the continental shelf area.Thus,the regulation mechanisms of the N dynamics in the carbonate sands of coral reefs are not clear.Taking the coral reef area of Weizhou Island,which has a relatively high N concentration,as the research object,we conducted a series of flow-through reactor experiments to investigate the fluxes of different N forms at the interface of sediment and seawater and their regulation mechanism by environmental factors.The fluxes of dissolved inorganic and organic N(DIN and DON)at different stations were-0.39-0.12 mmol/(m^(2)·h) and-0.18-0.39 mmol/(m^(2)·h),respectively.Denitrification(0.11-0.25 mmol/(m^(2)·h) was closely coupled to nitrification,which was limited by the availability of organic matter and its degradation product(i.e.,NH_(4)^(+)).Thus,the excessive NO_(3)^(-) might be reduced to NH4+by dissimilatory nitrate reduction to ammonium,rather than to N_(2) by denitrification.NO_(3)^(-) reduction peaked at intermediate advection rates(96 L/(m^(2)·h)) and flow path lengths(10 cm),but the release of DON also peaked at the same condition.In addition,climate warming would significantly affect sedimentary N dynamics at Weizhou Island.These results may help address the broader issue of the N cycle in coral reef eco systems under the dual pressure of climate warming and anthropogenic activities,and these results are beneficial to coral reef protection and local ecological management.

关 键 词：nitrogen dynamics SEDIMENTS coral reefs Weizhou Island 

分 类 号：P736.41[天文地球—海洋地质]