The effect of benthic macroinvertebrates on the release of CO2 and CH4 in sediments of urban river
Using the microcosms with Chironomus flaviplumus,Branchiura sowerbyi and Radix swinhoei of different perturbation functional groups,respectively,this study explored the influence of benthic bioturbation on key physio-chemical factors at the sediment-water interface(SWI)and on the release of CO2 and CH4.The following results were observed.Three macroinvertebrates differentially modified the content of dissolved oxygen(DO)of the interface and the aerobic/anaerobic decomposition of organic matter and the carbon conversion,which further affect the generation and release of CO2 and CH4.Firstly,there were significant differences in the release of CO2 and CH4,precisely as the following:B.sowerbyi exhibited the strongest promotion effect on the release of CO2 and CH4,and R.swinhoei showed no significant effect,while C.flaviplumus larvae inhibited the release of CH4.Secondly,B.sowerbyi consumed more carbon,promoted more release of CO2 and CH4,with its lowest DO infiltration depth creating a more favourable condition for the anaerobic decomposition of organic matter to produce more CH4.On the contrary,R.swinhoei,activating on the sediment surface,had relatively few change on the concentrations of DO,TC and TOC,and greenhouse gas.C.flaviplumus inhibited the release of CH4,probably due to inhibition of the anaerobic decomposition of organic matter under the increasing DO infiltration depth.
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