{"title":"Divergent impacts of animal bioturbation on methane and nitrous oxide emissions from mariculture ponds","authors":"Yanhong Dong, Junji Yuan, Junjie Li, Deyan Liu, Xian Wu, Huijie Zheng, Hui Wang, Huiqin Wang, Weixin Ding","doi":"10.1016/j.watres.2024.122822","DOIUrl":null,"url":null,"abstract":"Aquaculture systems are of increasing concern as an important source of atmospheric methane (CH<sub>4</sub>) and nitrous oxide (N<sub>2</sub>O). However, the role of animals in regulating CH<sub>4</sub> and N<sub>2</sub>O emissions from aquaculture systems remains unclear. Here, we established mesocosm trials to investigate impacts of bioturbation of different aquaculture species (i.e., clam, shrimp, and crab) on CH<sub>4</sub> and N<sub>2</sub>O fluxes in a mariculture pond. Across the initial, middle, and final culturing stages, mean CH<sub>4</sub> flux in mesocosm without animals was 4.81 ± 0.09 µg CH<sub>4</sub> m<sup>‒2</sup> h<sup>‒1</sup>, while the existence of clam, shrimp, and crab significantly increased CH<sub>4</sub> flux by 35.3%, 80.6%, and 138%, respectively. Bioturbation significantly decreased dissolved oxygen (DO) concentration by 5.19‒44.8% but increased porewater CH<sub>4</sub> concentration by 14.1‒59.9%, indicating that lowered DO caused by animal respiration promoted CH<sub>4</sub> production in sediment. Moreover, bioturbation of animals significantly increased ebullitive CH<sub>4</sub> fluxes by 41.0‒216%, contributing 57.4‒77.2% of the increased CH<sub>4</sub> emission in mesocosms with animals. However, shrimp and crab significantly reduced N<sub>2</sub>O flux by 30.3% and 42.5%, respectively, primarily due to lowered DO conditions suppressing nitrification and limiting NO<sub>3</sub><sup>‒</sup> supply for denitrification. By contrast, clam significantly increased N<sub>2</sub>O emission by 181% because its filter-feeding behavior excreted more NH<sub>4</sub><sup>+</sup> and NO<sub>3</sub><sup>‒</sup> into overlying water and thereby facilitating N<sub>2</sub>O production. The N<sub>2</sub>O concentration in overlying water was 1.72‒2.83-fold of that in porewater, and the calculated diffusive N<sub>2</sub>O flux was 1.80‒37.5% greater than chamber-measured N<sub>2</sub>O efflux. This implied that N<sub>2</sub>O might be primarily produced in overlying water rather than sediments, and the produced N<sub>2</sub>O can either evade as water-air fluxes or diffuse downwards into sediments to be consumed. Overall, our study advocates that aquaculture-related climate mitigation strategies should place more attention on the divergent impacts of animal bioturbation on CH<sub>4</sub> and N<sub>2</sub>O emissions.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"19 1","pages":""},"PeriodicalIF":11.4000,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Water Research","FirstCategoryId":"93","ListUrlMain":"https://doi.org/10.1016/j.watres.2024.122822","RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, ENVIRONMENTAL","Score":null,"Total":0}
引用次数: 0
Abstract
Aquaculture systems are of increasing concern as an important source of atmospheric methane (CH4) and nitrous oxide (N2O). However, the role of animals in regulating CH4 and N2O emissions from aquaculture systems remains unclear. Here, we established mesocosm trials to investigate impacts of bioturbation of different aquaculture species (i.e., clam, shrimp, and crab) on CH4 and N2O fluxes in a mariculture pond. Across the initial, middle, and final culturing stages, mean CH4 flux in mesocosm without animals was 4.81 ± 0.09 µg CH4 m‒2 h‒1, while the existence of clam, shrimp, and crab significantly increased CH4 flux by 35.3%, 80.6%, and 138%, respectively. Bioturbation significantly decreased dissolved oxygen (DO) concentration by 5.19‒44.8% but increased porewater CH4 concentration by 14.1‒59.9%, indicating that lowered DO caused by animal respiration promoted CH4 production in sediment. Moreover, bioturbation of animals significantly increased ebullitive CH4 fluxes by 41.0‒216%, contributing 57.4‒77.2% of the increased CH4 emission in mesocosms with animals. However, shrimp and crab significantly reduced N2O flux by 30.3% and 42.5%, respectively, primarily due to lowered DO conditions suppressing nitrification and limiting NO3‒ supply for denitrification. By contrast, clam significantly increased N2O emission by 181% because its filter-feeding behavior excreted more NH4+ and NO3‒ into overlying water and thereby facilitating N2O production. The N2O concentration in overlying water was 1.72‒2.83-fold of that in porewater, and the calculated diffusive N2O flux was 1.80‒37.5% greater than chamber-measured N2O efflux. This implied that N2O might be primarily produced in overlying water rather than sediments, and the produced N2O can either evade as water-air fluxes or diffuse downwards into sediments to be consumed. Overall, our study advocates that aquaculture-related climate mitigation strategies should place more attention on the divergent impacts of animal bioturbation on CH4 and N2O emissions.
期刊介绍:
Water Research, along with its open access companion journal Water Research X, serves as a platform for publishing original research papers covering various aspects of the science and technology related to the anthropogenic water cycle, water quality, and its management worldwide. The audience targeted by the journal comprises biologists, chemical engineers, chemists, civil engineers, environmental engineers, limnologists, and microbiologists. The scope of the journal include:
•Treatment processes for water and wastewaters (municipal, agricultural, industrial, and on-site treatment), including resource recovery and residuals management;
•Urban hydrology including sewer systems, stormwater management, and green infrastructure;
•Drinking water treatment and distribution;
•Potable and non-potable water reuse;
•Sanitation, public health, and risk assessment;
•Anaerobic digestion, solid and hazardous waste management, including source characterization and the effects and control of leachates and gaseous emissions;
•Contaminants (chemical, microbial, anthropogenic particles such as nanoparticles or microplastics) and related water quality sensing, monitoring, fate, and assessment;
•Anthropogenic impacts on inland, tidal, coastal and urban waters, focusing on surface and ground waters, and point and non-point sources of pollution;
•Environmental restoration, linked to surface water, groundwater and groundwater remediation;
•Analysis of the interfaces between sediments and water, and between water and atmosphere, focusing specifically on anthropogenic impacts;
•Mathematical modelling, systems analysis, machine learning, and beneficial use of big data related to the anthropogenic water cycle;
•Socio-economic, policy, and regulations studies.