Author(s): Lei Dong; Yueqi Cao; Xiong Pan; Li Lin; Jiancheng Hu; Xingrui Qi; Jiayu Guo
Linked Author(s):
Keywords: Three Gorges Reservoir; POPs; Vertical distribution
Abstract: Persistent organic pollutants (POPs) are organic chemicals that persist in the environment, accumulate through food webs, and adversely affect human health and the environment, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), etc. Insufficient knowledge exists regarding the historical sedimentary and evolutionary characteristics of persistent organic pollutants (POPs) in typical region of the three Gorges Reservoir. By combining 137Cs isotope dating techniques, the 96-year data on contaminants sedimentary history was reconstructed. Surface sediments in the TGR showed higher concentrations of PCBs, PAHs compared to those under the dam. PCBs in the sediment cores ranged from ND to 11.39 ng/g. The detection rates of PCB169 and PCB52 were both greater than 95%, and the detection rates of other PCBs were lower than 20%. It was found that there was no correlation between ∑PCBs and OM. Polycyclic aromatic hydrocarbons were the most widely distributed POPs in the reservoir area, sourced from biomass and coal burning. The concentrations of PAHs ranged from ND to 2075.20 ng/g, peaking in the 1970s due to natural, agricultural, and human activities during that period. 4–5 rings PAHs accounted for the largest proportion, 46.4% and 24.5%, respectively, while 2-ring PAHs accounted for the least, only 1.7% The vertical distribution pattern of POPs was mainly influenced by TN and OM. Additionally, a distance decay relationship was observed for POPs indicating a decrease in similarity with increasing depth in sediment core. Although current pollutant concentrations in the sediment do not pose a risk to the aquatic ecosystem, continuous attention is necessary.
Year: 2024