{"title":"Hypoxia exacerbate the marine ecological risk of arsenic: by stimulating its migration and release at the sediment-water interface","authors":"Liqin Duan, Jinming Song, Meiling Yin, Xiaoqi Liu, Xue Liu, Xuegang Li, Huamao Yuan","doi":"10.1016/j.watres.2024.122603","DOIUrl":null,"url":null,"abstract":"Hypoxia severally increased the release and bioavailability of sedimentary arsenic (As) in marine systems. However, the specific details regarding As migration and associated risks during exacerbated deoxygenation remain unclear. In this study, simulation experiments were conducted at four different dissolved oxygen (DO) levels to investigate the effects of exacerbated hypoxia on As mobility across the sediment-water interface (SWI). Hypoxia induced a rapid release of both As(V) and As(III), with a higher release rate for As(III) compared to As(V) across all experimental groups. The amount and rate of dissolved total As (dTAs) released across the SWI was proportional to the reduction in DO over the incubation time. The labile As in the solid phase was predominantly in the form of As(V) across all experimental groups. However, As(V) and As(III) were be dominant in surface and deep porewaters, respectively, accompanied by a decrease in the solid As in the reducible fraction and a significant increase in the abundance of the As(V)-reducing functional gene <em>arrA</em> with depth in the low DO groups. This suggested that hypoxia enhanced As exchange between surface sediment and overlying water by promoting the reductive dissolution of As(V)-bearing Fe/Mn oxides and exacerbated the partitioning of As from deep sediments to porewater by preferentially driving As(V) reduction. Although the diffusion of As to the overlying water was paralleled by dissolved Fe, there was a decoupling between them due to the involvement of As(V)-reducing bacteria and desorption of Mn oxides. After the completion of the hypoxia incubation, dTAs concentrations in the overlying water exceeded levels in clean coastal waters by ∼6-fold, reaching reported concentrations that affect the detoxification mechanisms of microalgae. Based on the estimation, about 34 t of As was released into the overlying water during the hypoxic period in the Changjiang Estuary, accounting for up to 17.3% of the surface sediment As capacity.","PeriodicalId":443,"journal":{"name":"Water Research","volume":null,"pages":null},"PeriodicalIF":11.4000,"publicationDate":"2024-10-10","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.2024.122603","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
Hypoxia severally increased the release and bioavailability of sedimentary arsenic (As) in marine systems. However, the specific details regarding As migration and associated risks during exacerbated deoxygenation remain unclear. In this study, simulation experiments were conducted at four different dissolved oxygen (DO) levels to investigate the effects of exacerbated hypoxia on As mobility across the sediment-water interface (SWI). Hypoxia induced a rapid release of both As(V) and As(III), with a higher release rate for As(III) compared to As(V) across all experimental groups. The amount and rate of dissolved total As (dTAs) released across the SWI was proportional to the reduction in DO over the incubation time. The labile As in the solid phase was predominantly in the form of As(V) across all experimental groups. However, As(V) and As(III) were be dominant in surface and deep porewaters, respectively, accompanied by a decrease in the solid As in the reducible fraction and a significant increase in the abundance of the As(V)-reducing functional gene arrA with depth in the low DO groups. This suggested that hypoxia enhanced As exchange between surface sediment and overlying water by promoting the reductive dissolution of As(V)-bearing Fe/Mn oxides and exacerbated the partitioning of As from deep sediments to porewater by preferentially driving As(V) reduction. Although the diffusion of As to the overlying water was paralleled by dissolved Fe, there was a decoupling between them due to the involvement of As(V)-reducing bacteria and desorption of Mn oxides. After the completion of the hypoxia incubation, dTAs concentrations in the overlying water exceeded levels in clean coastal waters by ∼6-fold, reaching reported concentrations that affect the detoxification mechanisms of microalgae. Based on the estimation, about 34 t of As was released into the overlying water during the hypoxic period in the Changjiang Estuary, accounting for up to 17.3% of the surface sediment As capacity.
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.