Cai Yuqun, Han Zhixuan, Lu Haotian, Zhao Ruiwei, Wen Meilan, Liu Hanliang, Zhang Bimin
Department of Earth Sciences, Guilin University of Technology, Guilin, Guangxi 541004, China.
Department of Earth Sciences, Guilin University of Technology, Guilin, Guangxi 541004, China; Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources, Guilin University of Technology, Guilin, Guangxi 541004, China; Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China.
J Hazard Mater. 2024 Feb 15;464:132981. doi: 10.1016/j.jhazmat.2023.132981. Epub 2023 Nov 10.
Lead (Pb) is a highly toxic element and is not essential to the human body. Lead pollution caused by human activities and a high geological background is considered a global environmental issue. According to the China Geochemical Baseline (CGB) project, the Pearl River Basin had the highest Pb content in alluvial sediments of 30 first-level basins in China. For this reason, it is of great significance to determine the temporal and spatial variations in Pb and their influencing factors in the Pearl River Basin. In this study, 956 stream sediment samples collected in the 1980 s (early stage) and 129 river sediment samples collected from 2008 to 2010 (late stage) were used to study the background value and spatial-temporal variation characteristics of Pb in river sediments in the Pearl River Basin. The Pb source apportionment and an ecological risk assessment were also carried out. The background value of Pb (36.2 mg·kg) in the river sediments of the Pearl River Basin was significantly higher than that in China (22.1 mg·kg). The parent rocks determine the Pb background in sediments and the high Pb background areas mainly comprised carbonate rocks and acid volcanic rocks. Over 20 years of rapid industrialisation, the average Pb increased from 43.3 to 68.3 mg·kg in the Pearl River Basin. The BCR analysis revealed that Pb mainly existed in the reducible phase (48 % on average) and residue phase (42 % on average). The enrichment factor and geo-accumulation index indicated that the late-stage sediments experienced more Pb pollution than the early-stage sediments. However, the risk assessment code (RAC) showed that there was a low ecological risk of Pb in the late-stage sediments. The factor analysis results for the two rounds of data were significantly different. The Pb content in early-stage sediments was closely related to AlO and Zr, while Pb in the late-stage sediments was mainly related to Zn, As, Sb, Au and Hg, indicating that the increase in Pb in the later samples was mainly influenced by human activities. The Pb isotope composition of the late-stage sediments confirmed that low Pb content was mainly controlled by natural sources, while high Pb content was significantly affected by anthropogenic sources. Combining the results of spatial-temporal variation, chemical speciation and source apportionment indicated that the rapid rise of Pb in late-stage sediments in certain areas could be attributed to mining and smelting activities during the process of industrialisation over 20 years. The anthropogenic exogenous Pb could be immobilised by Fe-Mn (hydro)oxides when it entered the soil, so although there was a high background the ecological risk of Pb in river sediments was low. In the future, Pb pollution control and remediation needs to be strengthened in the Pearl River Basin to avoid the outbreak of potential ecological risks linked to Pb.
铅（Pb）是一种剧毒元素，对人体并非必需。由人类活动和高地质背景导致的铅污染被视为一个全球环境问题。根据中国地球化学基准（CGB）项目，珠江流域在全国30个一级流域的冲积沉积物中铅含量最高。因此，确定珠江流域铅的时空变化及其影响因素具有重要意义。本研究利用20世纪80年代（早期）采集的956个河流沉积物样本和2008年至2010年（晚期）采集的129个河流沉积物样本，研究珠江流域河流沉积物中铅的背景值和时空变化特征。还进行了铅源解析和生态风险评估。珠江流域河流沉积物中铅的背景值（36.2 mg·kg）显著高于全国水平（22.1 mg·kg）。母岩决定了沉积物中的铅背景，高铅背景区域主要由碳酸盐岩和酸性火山岩组成。经过20多年的快速工业化，珠江流域的铅平均含量从43.3 mg·kg增加到68.3 mg·kg。BCR分析表明，铅主要存在于可还原态（平均48%）和残渣态（平均42%）。富集因子和地累积指数表明，晚期沉积物比早期沉积物受到更多的铅污染。然而，风险评估代码（RAC）显示晚期沉积物中铅的生态风险较低。两轮数据的因子分析结果差异显著。早期沉积物中的铅含量与AlO和Zr密切相关，而晚期沉积物中的铅主要与Zn、As、Sb、Au和Hg有关，这表明后期样本中铅的增加主要受人类活动影响。晚期沉积物的铅同位素组成证实，低铅含量主要受自然源控制，而高铅含量则受人为源显著影响。结合时空变化、化学形态和源解析结果表明，某些地区晚期沉积物中铅的快速上升可能归因于20多年工业化进程中的采矿和冶炼活动。人为外源铅进入土壤后可被铁锰（氢）氧化物固定，因此尽管背景值较高，但河流沉积物中铅的生态风险较低。未来，珠江流域需要加强铅污染控制和修复，以避免与铅相关的潜在生态风险爆发。
