Occurrence and cross-interface transfer of phthalate esters in the mangrove wetland in Dongzhai Harbor, China

Abstract

Phthalate esters (PAEs), the most widely used plasticizers, are extensively present in various environmental media, and are continuously transported from land to sea. However, PAEs have not been well characterized in multiple media in mangrove wetlands, an important land-sea interface. This study investigated the distribution and transfer of six PAEs in water, sediment, mangroves, and fish in Dongzhai Harbor. The mangrove forest in Dongzhai Harbor is the largest in China and is surrounded by shrimp ponds and villages. PAEs are ubiquitous in the study area. The mean concentration range of ∑6PAEs was 0.31–1.52 μg/L in water, 450–2096 μg/kg dry weight (dw) in sediment, 210–937 μg/kg dw in mangrove plants, and not detected (n.d.) -205 μg/kg in fish. Among the six PAEs, di-n-butyl phthalate (DBP) and di-ethylhexyl phthalate (DEHP) were predominant. The concentrations of the PAEs in mangrove plants tended to decrease from the river and coast to tidal gullies, which might be related to the periodic inundation of tides. A study of PAEs bioaccumulation showed that the concentration of PAEs in herbivorous fish was higher than that in carnivorous fish. In the same species, larger individuals had a lower concentration of ∑6PAEs. Di-n-octyl phthalate (DnOP) and DEHP tended to transfer from water to sediments, while the four less-hydrophobic PAEs, such as DBP, were more likely to be released from sediments to water. Our results can provide important information of the distribution and fate of PAEs in mangrove wetlands.