Unraveling sources of hydrocarbons in subtropical estuaries with distinct degrees of protection in the Southwestern Atlantic Ocean, Brazil

Identification of key anthropogenic and land use factors and ecological risk assessment of dissolved polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in an urbanized estuary in China

This study investigated dissolved PAHs and OCPs in Quanzhou Bay estuaries, assessed their ecological risk, and examined anthropogenic impacts on contaminant distribution. Results showed that dissolved ∑24PAH concentrations ranged from 117 to 709 ng/L (mean: 358 ng/L), with dominance of 2-ring PAHs (Naphthalene, 1-Methylnaphthalene, and 2-Methylnaphthalene). Dissolved DDT levels ranged from 0.06 to 0.49 ng/L (mean: 0.28 ng/L), while HCBz concentrations varied from 0.02 to 0.44 ng/L (mean: 0.20 ng/L). PAHs were higher in the north due to urbanization and transport, while OCPs showed higher levels in the south due to historical agricultural use. Rural areas, water bodies, and wetlands significantly influenced the behavior of PAHs according to Spearman correlation and lasso regression analyses. Quanzhou Bay was categorized as a low to medium risk area based on dispersion simulation and ecological risk assessment, highlighting implications for future sustainable development and policy planning. CAPSULE: The coupled relationship between human activities and the distribution of dissolved PAHs and OCPs in urbanized estuaries was explored using statistical methods and GIS technology, providing valuable insights into environmental processes and pollutant control policies.

Concentrations, sources and risks of polycyclic aromatic hydrocarbons in sediments from the Parnaiba Delta basin, Northeast Brazil

The Parnaíba River is the main river in the Parnaíba Delta basin, the largest delta in the Americas. About 18 polycyclic aromatic hydrocarbons (PAHs) were identified and the environmental risk associated with the sediments was evaluated. The study found that PAHs levels ranged from 5.92 to 1521.17 ng g-1, which was classified as low to high pollution, and that there were multiple sources of pollution along the river, with pyrolytic sources predominating, mainly from urban activity such as trucking, although the influence of rural activity cannot be ruled out. PAHs correlated with black carbon and organic matter and showed high correlation with acenaphthylene, phenanthrene, pyrene, benzo(a)anthracene, chrysene, benzo(ghi)perylene, and ∑PAHs. The benzo(a)pyrene levels were classified as a risk to aquatic life because the threshold effect level and the probable effect level were exceeded. In addition, the sediments were classified as slightly contaminated with a benzo(a)pyrene toxicity equivalent value of 108.43 ng g-1. Thus, the priority level PAH exhibited carcinogenic and mutagenic activity that posed a potential risk to human health.