Distribution, sources, and ecological risks of phthalate esters (PAEs) in sediments from Xincun and Li'an Lagoons, Lingshui, South China.

Abstract

Tropical lagoons are vulnerable coastal ecosystems where intensive aquaculture and plastic-related activities may promote the accumulation of phthalate esters (PAEs) in sediments. However, the distribution patterns, potential sources, and ecological risks of PAEs in tropical lagoon systems remain insufficiently understood. This study investigated 15 PAE compounds in surface sediments from Xincun and Li'an Lagoons, southern Hainan, China. All target PAEs were detected, with ΣPAEs concentrations ranging from 365 to 1438 ng/g dw. DBP, DiBP, and DEHP were the dominant compounds, accounting for 80.7% of total PAEs. PAE concentrations were generally higher in lagoon interiors than at outlets, reflecting the combined effects of semi-enclosed hydrodynamic conditions, anthropogenic inputs, and tidal dilution. Principal component analysis suggested that PAE contamination was mainly associated with plastic-related materials, aquaculture activities, domestic wastewater, and waste-related inputs, although these source interpretations remain qualitative. HQ-based ecological risk assessment revealed clear species-specific differences. DBP was identified as the primary risk contributor, posing high risks to algae (HQ ≥ 1) at all sampling sites, while DiBP showed medium risks to fish at 10.0% of sites. These findings highlight the need to prioritize DBP and DiBP in future monitoring programs. Effective management should focus on reducing plastic waste and aquaculture-related inputs, improving domestic wastewater treatment, and strengthening pollution control in highly impacted lagoon areas. This study provides baseline information for understanding PAE contamination and supporting sustainable management of tropical lagoon ecosystems.