Spatial-temporal variation, source apportionment and risk assessment of lead in surface river sediments over ∼20 years of rapid industrialisation in the Pearl River Basin, China

Yuqun Cai; Zhixuan Han; Haotian Lu; Ruiwei Zhao; Meilan Wen; Hanliang Liu; Bimin Zhang

doi:10.1016/j.jhazmat.2023.132981

Spatial-temporal variation, source apportionment and risk assessment of lead in surface river sediments over ∼20 years of rapid industrialisation in the Pearl River Basin, China

J Hazard Mater. 2024 Feb 15:464:132981. doi: 10.1016/j.jhazmat.2023.132981. Epub 2023 Nov 10.

Authors

Yuqun Cai¹, Zhixuan Han², Haotian Lu¹, Ruiwei Zhao¹, Meilan Wen¹, Hanliang Liu³, Bimin Zhang⁴

Affiliations

¹ Department of Earth Sciences, Guilin University of Technology, Guilin, Guangxi 541004, China.
² 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. Electronic address: hanzhixuan1987@126.com.
³ Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences, Langfang, Hebei 065000, China.
⁴ Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences, Langfang, Hebei 065000, China. Electronic address: zbimin@hotmail.com.

PMID: 37992505
DOI: 10.1016/j.jhazmat.2023.132981

Abstract

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^-1) in the river sediments of the Pearl River Basin was significantly higher than that in China (22.1 mg·kg^-1). 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^-1 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 Al₂O₃ 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.

Keywords: BCR; Ecological risk; Factor analysis; Lead; Lead isotopes; Pearl River Basin; River sediments.