Occurrence and Ecological Risk Assessment of Typical Persistent Organic Pollutants in Hengshui Lake

Abstract

Sediment samples were collected from 11 typical sites in Hengshui Lake separately in August 2018 and March 2019. Characteristics and ecological risk assessment of typical persistent organic pollutants (POPs), including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs), in these sediments were analyzed. The results showed that the average content of ΣPAHs in sediments of Hengshui Lake was 875.49 ng·g-1 and 1010.17 ng·g-1 in August 2018 and March 2019, respectively. Compared with other regions in China and abroad, ΣPAHs in sediments from Hengshui Lake were at moderate pollution level. Distribution of ΣPAHs varied between different sites, but the values changed within a narrow range in different seasons. Sources of PAHs in sediments from Hengshui Lake were complex, but combustion of wood and coal was the main source, followed by oil pollution. Generally, the ecological risk of PAHs was at a low level. However, fluorene pollution control should be strengthened. For ΣOCPs, the average values in sediments were 35.57 ng·g-1 and 38.39 ng·g-1 in August and March, respectively. Compared with other regions, the pollution of ΣOCPs was at a moderate level. In addition, the distribution of ΣOCPs varied a small amount between different sites. There were significant differences between the two seasons. The contents of DDTs in sediments were mainly related to the residual DDTs after long-term soil weathering and the input of recent DDTs sources. Contents of HCHs in sediments were influenced by the use of HCHs in industrial history and inputs of agricultural lindane. Generally, the ecological risk of OCPs was at a medium level, but the DDTs pollution control should be strengthened. For ΣPBDEs, the average values were 1.77 ng·g-1 and 1.45 ng·g-1 in the sediments in August 2018 and March 2019, respectively. Compared with other regions, they were at a lower pollution level. The distribution of ΣPBDEs showed small differences between different sites, and did not obviously vary between spring and summer. The PBDEs in sediments were mainly low-bromine PBDEs, which might be contaminated with penta-BDEs from textiles and foams. Additionally, PBDEs were also probably input by distant settlement and migration from the atmosphere, and soil flushing into the lake. PBDEs posed no immediate ecological risk.