PAHs in sediments and shrimps: Levels, sources, and risk estimation in a tropical coastal lagoon system near oil industry

Anthropogenic activities in the surrounding the Tehuantepec Isthmus Lagoon System (Mexican South Pacific) region are related to the emission of polycyclic aromatic hydrocarbons (PAHs), such as the Salina Cruz oil refinery, the combustion of fossil fuels, and the traditional agricultural method of "slash and burn." Therefore, PAHs have impacted shrimp fishery resources and increased human health risks of Indigenous communities such as Huaves and Zapotecos, increasing their vulnerability. PAHs were quantified in sediments and shrimp in dry, rainy, and cold front seasons; sources, ecotoxicological risk, and the bioconcentration factor in shrimp were estimated. Σ16PAHs in sediments were 166-5286.8 ng g^-1 (dw) and for shrimp were 100.9-8155.8 ng g^-1. Seasonal factors and Tehuano winds were essential in the PAHs distribution. Pyrogenic PAHs were dominant during the dry and the cold front seasons from industrial sources; meanwhile, petrogenic PAHs were dominant in the rainy season from river runoff and oil-fuel spill sources. PAHs levels were not correlated with organic matter in sediments (Spearman r = 0.1368, p = 0.4964). Petrogenic and pyrogenic PAHs sources were identified. The most concerning findings are the high bioaccumulation factor levels found in shrimp (553 for dibenzo[a,h]anthracene) and the identified environmental medium-high risk found in the fishery areas estimated by the Mean Maximum Permissible Concentration Quotient, which suggest a possible high health risk Indigenous communities in the region. This study could help to have better public policies in environmental management for tropical coastal ecosystems affected by the oil industry worldwide.