Trophic Transfer of Halogenated Organic Pollutants in a Wetland Food Web: Insights from Compound-Specific Nitrogen Isotope of Amino Acids and Food Source Analysis

A trophic position (TP) model (TP mix model) that simultaneously considered trophic discrimination factor and β Glu/Phe variations was developed in this study and was first applied to investigate the trophic transfer of halogenated organic pollutants (HOPs) in wetland food webs. The TP mix model characterized the structure of the wetland food web more accurately and significantly improved the reliability of TMF compared to the TP bulk, TP AAs, and TP simmr models, which were calculated based on the methods of stable nitrogen isotope analysis of bulk, traditional AAs-N-CSIA, and weighted β Glu/Phe, respectively. Food source analysis revealed three interlocking food webs (kingfisher, crab, and frogs) in this wetland. The highest HOP biomagnification capacities (TMF mix ) were found in the kingfisher food web (0.24–82.0), followed by the frog (0.08–34.0) and crab (0.56–11.7) food webs. The parabolic trends of TMF mix across combinations of log K OW in the frog food web were distinct from those of aquatic food webs (kingfisher and crab), which may be related to differences in food web composition and HOP bioaccumulation behaviors between aquatic and terrestrial organisms. This study provides a new tool to accurately study the trophic transfer of contaminants in wetlands and terrestrial food webs with diverse species and complex feeding relationships.