Source and Distribution of Emerging and Legacy Persistent Organic Pollutants in the Basins of the Eastern Indian Ocean

Persistent organic pollutants (POPs) have received significant and ongoing attention. To establish favorable regulatory policies, it is vital to investigate the occurrence, source, and budgets of POPs worldwide. POPs including phthalic acid esters (PAEs), organophosphate esters (OPEs), brominated flame retardants (BFRs), and highly chlorinated flame retardants (HFRs) have not yet been examined in the Eastern Indian Ocean (EIO). In this study, the distribution of POPs has been investigated from surface sediments with the depth of 4369–5742 m in the Central Indian Ocean Basin (CIOB) and Wharton Basin (WB) of EIO. The average (±SD) concentrations of ∑11PAEs, ∑11OPEs, ∑4 BFRs, and ∑5HFRs were 1202.0 ± 274.36 ng g–1 dw, 15.3 ± 7.23 ng g–1 dw, 327.6 ± 211.74 pg g–1 dw, and 7.9 ± 7.45 pg g–1 dw, respectively. The high abundance of low-molecular-weight (LMW) PAEs, chlorinated OPEs, LMW BDEs, and anti-Dechlorane Plus indicated the pollution characteristics in the EIO. Correlation analysis demonstrated that LMW compounds may be derived from the high-molecular-weight compounds. The monsoon circulation, currents, and Antarctic Bottom Water may be the main drivers. POP accumulation rate, depositional flux, and mass inventory in the Indian Ocean were also estimated.