Distribution and region-specific sources of Dechlorane Plus in marine sediments from the coastal East China Sea

- The first records of DP were reported in coastal East China Sea.
- Higher levels of DP were detected in the southern inner shelf.
- Regional sources of DP were identified by using lignin and n-alkanes.
- Enrichment of syn-DP was found in marine sediments.
- anti-DP was more vulnerable to degradation during LRAT and after burial.

Dechlorane Plus (DP) is a highly chlorinated flame retardant and found to be ubiquitously present in the environment. We reported here the first record of DP in sediments from the coastal East China Sea (ECS). DP was detected in most of the surface sediments, and the concentrations ranged from 14.8 to 198 pg/g dry weight (dw) with a mean value of 64.4 pg/g dw. Overall, DP levels exhibited a seaward decreasing trend from the inshore toward outer sea. The fractional abundance of anti-DP (fanti) showed regional discrepancies, attributing to different environmental behaviors of DP isomers. Depth profiles of DP in a sediment core from estuarine environment showed distinct fluctuation, and the core in open sea had stable deposition environment with two peak values of DP in ~ 1978 and 2000. The fanti exhibited downward decreasing trend prior to mid-1950s, indicating a preferential degradation of anti-DP and/or a greater adsorption capacity of syn-DP after its burial. Lignin and lipid biomarkers (∑ C27 + C29 + C31n-alkanes) of terrestrial organic matters were introduced to identify region-specific sources of DP, and the results showed that DP in the northern inner shelf, southern inner shelf of 29 °N and mud area southwest of Cheju Island was mainly come from Yangtze River (YR) input, surface runoffs after discharge of local sources close to the Taizhou-Wenzhou Region and the atmospheric deposition from the North China and East Asia, respectively. The coastal ECS was an important reservoir of DP in the world, with mass inventory of approximately 310.7 kg in the surface sediments (0-5 cm).

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