Organophosphate Ester Migration Mechanisms and Environmental Impacts in the Western South China Sea

Organophosphate esters (OPEs) are ubiquitous in various environmental media and are of concern because of their toxicity and potential ecological impacts. However, their transport mechanisms and ecological effects in marine environments remain poorly understood. Herein, we comprehensively investigated the occurrence and distribution of OPEs in multiple environmental media (atmosphere, rainwater, seawater, and sediments) in the western South China Sea (WSCS). Results show that OPEs are widespread in the WSCS. OPE concentrations in the atmosphere were higher than those reported in most other marine regions globally, whereas concentrations in seawater were either lower than or comparable to those in other oceanic regions. The biogeochemical cycling of OPEs is driven primarily by particulate matter (PM) and microbial activity. PM facilitates the transport of 65.3-98.4% of total OPEs and 60.5-100% of chlorinated OPEs from the atmosphere to the ocean. PM sinking strongly influences the vertical distribution of OPEs, while microorganisms contribute to OPE biodegradation through community succession, differentiation of ecological niches among key functional groups, and hydrolytic enzyme activity. Given the increasing concentrations of OPEs in the South China Sea, it is imperative to conduct comprehensive and continuous investigations of their migration mechanisms and impacts on marine ecosystems, particularly coral reefs.