Characteristics and origins of methoxypolybrominated diphenyl ethers in tuna

Tuna, top predators in the marine food chain, are widely distributed in global oceans. It possess a strong capability for pollutant accumulation. Thus, tuna is commonly used as a vital bioindicator of marine pollution. In this study, 129 tuna samples were collected from the Pacific, Atlantic, and Indian Oceans. MeO-BDEs were measured in their livers, in order to investigate the occurrence, distribution patterns, influencing factors, and potential sources. The results revealed two categories of MeO-BDEs were frequently detected in the samples, specifically 2’-MeO-BDE-68 and 6-MeO- BDE-47, which could be of natural origin. Further single-factor and multi-factor correlation analysis revealed a correlation between MeO-BDEs concentration in tuna and its habitat, with differences in sources among various habitats. A positive correlation between concentrations and δ¹³C (indicating food sources) was observed, suggesting MeO-BDEs associated with their respective habitats. Additionally, a weak negative correlation between δ¹⁵N and body length was due to the potential conversion of MeO-BDEs within larger tuna organisms at higher trophic levels. The results are helpful to understand the distribution characteristics of MeO-BDEs in tuna worldwide and the potential sources of these pollutants.