Investigation of plastic related organic chemicals in the marine environment

Abstract

Phthalate esters (PAEs) and organophosphate esters (OPEs) are widely used as plasticizers and flame retardants in various industrial and consumer products, making them ubiquitous in the environment. Both PAEs and OPEs persist in the environment and can accumulate in organisms. They are currently of environmental concern due to their toxicity and endocrine-disrupting effects. Understanding their distribution and transport in marine environments is very important for assessing their environmental impact and developing mitigation strategies. This study aims to enhance our understanding of the distribution patterns and transport mechanisms of PAEs and OPEs in the Chinese marginal seas, with a particular focus on the roles of air-sea exchanges in these processes. In the South China Sea, atmospheric concentrations of OPEs ranged from 66 to 550 pg/m³, while seawater concentrations averaged 1180 ± 910 pg/L. Air-sea exchange fluxes indicated volatilization of some OPEs and deposition of others. Atmospheric particle deposition fluxes ranged from 5 to 71 ng/m²/day. The input of ∑OPEs via atmospheric deposition was estimated at 22 ± 19 tons/year, with net fluxes indicating volatilization from seawater to air at 44 ± 33 tons/year. PAEs were measured in the air and seawater of the Bohai and Yellow Seas in spring 2019. Atmospheric PAE concentrations ranged from 9.59 to 51.3 ng/m³, with seawater concentrations averaging 466 ± 268 ng/L. In summer 2019, PAEs in the South China Sea showed atmospheric concentrations ranging from 2.84 to 24.3 ng/m³ and seawater concentrations averaging 3.05 ng/L. Monsoon currents and cyclones significantly influence their concentrations and transport. The input of ∑PAEs via atmospheric deposition was about 579 ± 222 tons/year, with net fluxes showing a predominance of PAEs moving from seawater to air at 1540 ± 1430 tons/year in the Bohai and Yellow Seas. In the South China Sea, net atmospheric depositions were 3740 tons/year for DMP, DEP, DiBP, and DnBP, and DEHP volatilization was 900 tons/year. Additionally, sedimentation has been identified as a significant sink for PAEs in the Bohai and Yellow Seas, with an inventory of 20.73 tons/year in the Bohai Sea and 65.87 tons/year in the Yellow Sea. These results suggest that air-sea exchange and atmospheric deposition are important processes in the transport of PAEs and OPEs in the Chinese marginal seas.