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典型废渣中天然放射性核素的释放特性

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赤泥和锰渣等伴生放射性固体废物的放射性风险越来越受到人们的关注.本研究分析了贵州典型的赤泥和锰渣样中238U、232Th、226Ra和40K这4种天然放射性核素的含量与分布特征,利用静态浸泡实验研究了其释放特性,并对浸出液的释放风险进行评价.结果表明,新产生的赤泥中天然放射性核素含量较老化赤泥高,电解锰渣中天然核素含量低于锰矿渣.废渣浸出液中核素比活度依次是40K＞226Ra＞238U＞232Th,但固液分配系数(Kd)显示废渣天然核素的释放能力为226Ra＞40K＞238U＞232Th,226Ra易被水浸泡或淋滤释放进入水体产生环境风险.基于世界卫生组织(WHO)饮用水水质准则和美国环境保护局(United Stated Environmental Protection Agency,US EPA)水环境质量标准的放射性核素风险评价结果显示,232Th水浸释放的环境风险较小;随着浸泡时间增加,锰渣中238U在90 d时均超过了WHO(10 Bq·L-1)和US EPA(11.1 Bq·L-1)限值,赤泥中仅老化赤泥在90 d时超出WHO限值.废渣浸泡7 d内226Ra均已超出WHO(1.0 Bq·L-1)和US EPA(222 Bq·L-1)的限值,226Ra释放风险随着浸泡时间增加导致不断增高,第90天时新鲜赤泥分别超出31.09倍和14.00倍.226Ra释放产生的高风险应该引起足够的重视,也应是废渣中天然放射性核素释放风险管控的重点对象.
Releasing Characteristics of Natural Radionuclides from Representative Waste Residues
The radioactive risk of radioactive solid wastes concomitant with red mud and manganese residue has attracted growing concern.The content and distribution characteristics of four natural radioactive nuclides(238U,232Th,226Ra,and 40K)of typical red mud(RM)and manganese residue(MR)in Guizhou Province were investigated in this study,the release characteristics were also investigated by using the static immersion experiment,and the releasing risk of leachate was further assessed.The results showed that the content of natural radionuclides in the fresh produced red mud(FRM)is higher than that in the aged red mud(ARM),and the content of natural radionu-clides in the electrolytic manganese residue(EMR)is lower than that in the tailings of manganese ore(TMO).The specific activities of the nuclides in the leachate from waste residues followed the order of 40K＞226Ra＞238U＞232Th,while the releasing capacity of these nuclides in waste residues followed the sequence of 226Ra＞40K＞238U＞232Th based on the solid-solution distribution coefficient(Kd),and the 226 Ra was more easily released into water body by soaking and leaching,further resulting in environmental risks.The risks of radionuclides were evaluated according to the guidelines for drinking water quality of the World Health Organization(WHO)and the water quality standards of the U.S.Environmental Protection Agency(US EPA).The evaluated results presented that the environmental risk of 232Th released from waste residues via leaching was low.As the leaching time increased,the 238U in leachate of MRs exceeded both the limits of WHO(10 Bq·L-1)and US EPA(11.1 Bq·L-1)on 90th day,whereas only the ARM presented the 238 U content greater than the limits of WHO on 90th day.On a 7-day scale,226 Ra of leachate from waste residues consistently exceeded the limits of WHO(1.0 Bq·L-1)and US EPA(2.22 Bq·L-1),and the releasing risk of 226 Ra increased with the increasing immersion time.The 226 Ra releasing from FRM exceeded the limits of WHO and US EPA by 31.09 and 14.00 times on the 90th day,respectively.Therefore,the high releasing risk of 226 Ra from waste residues should be paid more attention,and 226 Ra should be considered as the main target in releasing risk management and control of natural radionuclides in waste residues.

waste residuesnatural radionuclidesstatic immersionsolid-solution distribution coefficientradioac-tive risk

周廷艺、林发利、韩志伟、吴攀、何守阳

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喀斯特地质资源与环境教育部重点实验室(贵州大学),贵阳 550025

贵州大学资源与环境工程学院,贵阳 550025

贵州喀斯特环境生态系统教育部野外科学观测研究站,贵阳 550025

贵州大学北阿拉巴马大学国际工程技术学院,贵阳 550025

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废渣 天然放射性核素 静态浸泡 固液分配系数 放射性风险

国家自然科学基金国家自然科学基金国家重点研发计划贵州省自然科学基金贵州省自然科学基金贵州大学人才引进项目

U1612442422670142022YFC370500黔科合J字[2011]2037号黔科合基础-ZK[2004]重点018贵大人基合字2010046号

2024

10.7524/AJE.1673-5897.20240120001

生态毒理学报
中国科学院生态环境研究中心

生态毒理学报

CSTPCD北大核心
影响因子：0.857
ISSN：1673-5897
年,卷(期)：2024.19(4)