摘要
放射性核素作为一类被广泛关注的危险物质,红树林典型生态系统中放射性核素研究极少。本研究利用高纯锗γ谱仪探索广西防城港核电站周边10处不同地点的红树林表层及沉积物柱样中天然放射性核素含量及分布特征。结果表明,红树林区表层沉积物中238U、226Ra、228Ra、40K活度范围分别为6.2~70.7 Bq/kg、7.3~55.3 Bq/kg、10.0~94.1 Bq/kg、26.5~479 Bq/kg,对应均值为(27.8±19.8) Bq/kg、(21.2±13.9) Bq/kg、(35.8±24.8) Bq/kg、(177±131)Bq/kg;不同深度的沉积物柱样中238U、226Ra、228Ra、40K活度与表层沉积物的结果接近,4种核素在垂向上的含量均无显著增加或者减少的变化趋势。广西防城港核电周边红树林沉积物中放射性水平低于广西、全国、全球的土壤和我国大部分海域的放射性水平,仅高于南海珊瑚礁区极低的放射性水平。此外,红树林沉积物中226Ra/238U活度比值与我国其他海区沉积物的结果一致,范围在0.5~1.0,但是显著高于珊瑚礁区的226Ra/238U活度比值(226Ra/238U<0.1),说明地质成因的红树林沉积物(和其它海区沉积物)与生物成因的珊瑚礁沉积物存在显著不同的物质来源机制。总之,本研究结果表明广西红树林系统中天然放射性核素不存在富集现象。
As one of widely concerned hazardous materials, radioactivity in the mangrove ecosystems is rarely studied. In this study, we presented radioactivity in surface sediments and sediment core collected from 10 locations of mangrove ecosystems nearby the Fangchenggang Nuclear Power Plant using high purity germanium γ spectrometry in order to explore the enrichment of radionuclides in the mangrove systems. The activities of 238U, 226Ra, 228Ra, and 40K in surface sediments were in the range of 6.2~70.7 Bq/kg, 7.3~55.3 Bq/kg, 10.0~94.1 Bq/kg, and 26.5~479 Bq/kg with the mean value of(27.8±19.8) Bq/kg,(21.2±13.9) Bq/kg,(35.8±24.8) Bq/kg,(177±131) Bq/kg, respectively. The activities of 238U, 226Ra, 228 Ra and 40 K in sediment core were consistent with that in surface sediment. No significant trend was observed for the vertical profile of these naturally occurring radionuclides(238U, 226Ra, 228Ra, and 40K). We found that radioactivity in the mangrove ecosystems was lower than that in Guangxi soil, China soil, global soil, other sea regions except coral reefs. The activity ratio of 226Ra/238U in surface sediments from the mangrove ecosystems was consistent with that from other sea regions, ranging from 0.5 to 1.0. However, the significant difference of the activity ratio of 226Ra/238U between the mangrove ecosystems(0.5~1.0) and coral reefs(<0.1) was determined by distinct sediment sources with geologically originating sediment in the mangrove ecosystems and biogenic carbonate sediment in coral reefs, respectively. Overall, the enrichment of radionuclides was not observed in the mangrove ecosystems in Guangxi.
作者
林武辉
莫敏婷
宁秋云
莫珍妮
刘昕明
冯禹
冯亮亮
何贤文
LIN Wu-hui;MO Min-ting;NING Qiu-yun;MO Zhen-ni;LIU Xin-ming;FENG Yu;FENG Liang-liang;HE Xian-wen(School of Marine Sciences,Guangxi University,Nanning 530004,China;Guangxi Laboratory on the study of Coral Reefs in the South China Sea,Nanning 530004,China;Guangxi Academy of Oceanography,Nanning 530022,China;Radiation-Environment Management and Monitoring Station of Guangxi Zhuang Autonomous Region,Nanning 530222,China)
出处
《海洋环境科学》
CAS
CSCD
北大核心
2020年第5期676-683,共8页
Marine Environmental Science
基金
国家重点研发计划(2017YFC0506104)
广西自然科学基金(2017GXNSFBA198096)
国家海洋局海洋-大气化学与全球变化重点实验室开放基金(GCMAC1606)。
关键词
红树林
沉积物
放射性核素
珊瑚礁
核电站
mangrove
sediment
radionuclide
coral reefs
nuclear power plant
