Salinity stress changed the biogeochemical controls on CH4 and N2O emissions of estuarine and intertidal sediments

Elevated salinity is expected to drive changes in biogeochemical cycling and microbial communities in estuarine
and intertidal wetlands. However, limited information regarding the role of salinity in shaping biogeochemical
controls andmediating greenhouse gas emissions is currently available. In this study,we used incubation experiment
across salinity gradients of the estuarine and intertidal sediments to reveal the underlying interconnections
of CH4 and N2O emissions, biogeochemical controls and salinity gradients. Our results indicated that
sediment biogeochemical propertieswere significantly affected by the increasing salinity, whichwere attributed
to the accelerated sediment enzyme activities. The increasing salinity promoted CH4 and N2O emission rates by
stimulating organic carbon decomposition and nitrogen transformation rates. In addition, the copy number of
mcrA, nirS and nirK genes increased along with the salinity gradients, which strongly mediated the CH4 and
N2O emission rates. Stepwise regression analysis suggested that labile organic carbon and denitrification were
the most crucial determinants of CH4 and N2O emission rates, respectively. Overall, salinity could enhance CH4
and N2O emission mainly by altering sediment geochemical variables, microbial activity and functional gene
abundance in estuarine and intertidal environments. Furthermore, increasing salinity could enhance the carbon
and nitrogen export, which may pose a threat to the ecological function of estuarine and intertidal ecosystems.
This studymay contribute to the knowledge about the importance of biogeochemical controls induced by salinity
in mediating greenhouse gas emissions.
刊物名称: 
Science of the Total Environment
年: 
2019
卷期: 
652
页码: 
593-601
作者: 
Xiaofei Li⁎, Dengzhou Gao, Lijun Hou, Min Liu
论文原文: