Juan C. Rincón-Rodríguez, Paula A. Cárdenas-Hernández, Jimmy Murillo-Gelvez, Dominic M. Di Toro, Herbert E. Allen, Richard F. Carbonaro, Pei C. Chiu
{"title":"比较评估介导电化学还原法和化学氧化还原滴定法量化土壤和具有氧化还原作用的土壤成分的电子接受能力","authors":"Juan C. Rincón-Rodríguez, Paula A. Cárdenas-Hernández, Jimmy Murillo-Gelvez, Dominic M. Di Toro, Herbert E. Allen, Richard F. Carbonaro, Pei C. Chiu","doi":"10.1021/acs.est.4c06514","DOIUrl":null,"url":null,"abstract":"The electron accepting capacity (EAC) of soil plays a pivotal role in the biogeochemical cycling of nutrients and transformation of redox-labile contaminants. Prior EAC studies of soils and soil constituents utilized different methods, reductants, and mediators, making cross-study comparison difficult. This study was conducted to quantify and compare the EACs of two soil constituents (hematite and Leonardite humic acid) and 12 soils of diverse composition, using chemical redox titration (CRT) with dithionite as the reductant and mediated electrochemical reduction (MER) with diquat as the mediator. The EACs of hematite and humic acid measured by CRT (EAC<sub>CRT</sub>) and MER (EAC<sub>MER</sub>) are similar and close to the theoretical/reported values. For soils, EAC<sub>CRT</sub> and EAC<sub>MER</sub> increased with iron and organic carbon (TOC) contents, suggesting iron and carbon were the main contributors to soil EAC. EAC<sub>CRT</sub> > EAC<sub>MER</sub> for all soils, and their difference (ΔEAC = EAC<sub>CRT</sub> <b>–</b> EAC<sub>MER</sub>) increased with TOC, presumably due to the longer contact time in CRT and thus more complete reduction of carbonaceous redox moieties. We propose an equation that relates EAC<sub>CRT</sub> to EAC<sub>MER</sub> (ΔEAC = 1796<i>f</i><sub>TOC</sub> + 32) and another that predicts EAC<sub>CRT</sub> from dithionite-reducible Fe and TOC (EAC<sub>CRT</sub> = 2705 μmol e<sup>–</sup>/g C × <i>f</i><sub>TOC</sub> + 17907 μmol e<sup>–</sup>/g Fe × <i>f</i><sub>Fe<sub>dithionite-reducible</sub></sub>). Our results suggest that at least 10−15% of soil organic carbon contributed to EAC<sub>CRT</sub>.","PeriodicalId":36,"journal":{"name":"环境科学与技术","volume":null,"pages":null},"PeriodicalIF":10.8000,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Comparative Evaluation of Mediated Electrochemical Reduction and Chemical Redox Titration for Quantifying the Electron Accepting Capacities of Soils and Redox-Active Soil Constituents\",\"authors\":\"Juan C. Rincón-Rodríguez, Paula A. Cárdenas-Hernández, Jimmy Murillo-Gelvez, Dominic M. Di Toro, Herbert E. Allen, Richard F. Carbonaro, Pei C. Chiu\",\"doi\":\"10.1021/acs.est.4c06514\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The electron accepting capacity (EAC) of soil plays a pivotal role in the biogeochemical cycling of nutrients and transformation of redox-labile contaminants. Prior EAC studies of soils and soil constituents utilized different methods, reductants, and mediators, making cross-study comparison difficult. This study was conducted to quantify and compare the EACs of two soil constituents (hematite and Leonardite humic acid) and 12 soils of diverse composition, using chemical redox titration (CRT) with dithionite as the reductant and mediated electrochemical reduction (MER) with diquat as the mediator. The EACs of hematite and humic acid measured by CRT (EAC<sub>CRT</sub>) and MER (EAC<sub>MER</sub>) are similar and close to the theoretical/reported values. For soils, EAC<sub>CRT</sub> and EAC<sub>MER</sub> increased with iron and organic carbon (TOC) contents, suggesting iron and carbon were the main contributors to soil EAC. EAC<sub>CRT</sub> > EAC<sub>MER</sub> for all soils, and their difference (ΔEAC = EAC<sub>CRT</sub> <b>–</b> EAC<sub>MER</sub>) increased with TOC, presumably due to the longer contact time in CRT and thus more complete reduction of carbonaceous redox moieties. We propose an equation that relates EAC<sub>CRT</sub> to EAC<sub>MER</sub> (ΔEAC = 1796<i>f</i><sub>TOC</sub> + 32) and another that predicts EAC<sub>CRT</sub> from dithionite-reducible Fe and TOC (EAC<sub>CRT</sub> = 2705 μmol e<sup>–</sup>/g C × <i>f</i><sub>TOC</sub> + 17907 μmol e<sup>–</sup>/g Fe × <i>f</i><sub>Fe<sub>dithionite-reducible</sub></sub>). Our results suggest that at least 10−15% of soil organic carbon contributed to EAC<sub>CRT</sub>.\",\"PeriodicalId\":36,\"journal\":{\"name\":\"环境科学与技术\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":10.8000,\"publicationDate\":\"2024-09-26\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"环境科学与技术\",\"FirstCategoryId\":\"1\",\"ListUrlMain\":\"https://doi.org/10.1021/acs.est.4c06514\",\"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}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"环境科学与技术","FirstCategoryId":"1","ListUrlMain":"https://doi.org/10.1021/acs.est.4c06514","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}
Comparative Evaluation of Mediated Electrochemical Reduction and Chemical Redox Titration for Quantifying the Electron Accepting Capacities of Soils and Redox-Active Soil Constituents
The electron accepting capacity (EAC) of soil plays a pivotal role in the biogeochemical cycling of nutrients and transformation of redox-labile contaminants. Prior EAC studies of soils and soil constituents utilized different methods, reductants, and mediators, making cross-study comparison difficult. This study was conducted to quantify and compare the EACs of two soil constituents (hematite and Leonardite humic acid) and 12 soils of diverse composition, using chemical redox titration (CRT) with dithionite as the reductant and mediated electrochemical reduction (MER) with diquat as the mediator. The EACs of hematite and humic acid measured by CRT (EACCRT) and MER (EACMER) are similar and close to the theoretical/reported values. For soils, EACCRT and EACMER increased with iron and organic carbon (TOC) contents, suggesting iron and carbon were the main contributors to soil EAC. EACCRT > EACMER for all soils, and their difference (ΔEAC = EACCRT– EACMER) increased with TOC, presumably due to the longer contact time in CRT and thus more complete reduction of carbonaceous redox moieties. We propose an equation that relates EACCRT to EACMER (ΔEAC = 1796fTOC + 32) and another that predicts EACCRT from dithionite-reducible Fe and TOC (EACCRT = 2705 μmol e–/g C × fTOC + 17907 μmol e–/g Fe × fFedithionite-reducible). Our results suggest that at least 10−15% of soil organic carbon contributed to EACCRT.
期刊介绍:
Environmental Science & Technology (ES&T) is a co-sponsored academic and technical magazine by the Hubei Provincial Environmental Protection Bureau and the Hubei Provincial Academy of Environmental Sciences.
Environmental Science & Technology (ES&T) holds the status of Chinese core journals, scientific papers source journals of China, Chinese Science Citation Database source journals, and Chinese Academic Journal Comprehensive Evaluation Database source journals. This publication focuses on the academic field of environmental protection, featuring articles related to environmental protection and technical advancements.