Persistent Organochlorine Residues and Their Bioaccumulation Profiles in Resident and Migratory Birds From North Vietnam

Abstract

Concentrations of persistent organochlorines (OCs), such as polychlorinated biphenyls (PCBs), 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), and chlordane compounds (CHLs), were determined in whole-body homogenates of resident and migratory birds collected from the Red River estuary, North Vietnam, during March and October 1997. Contamination pattern was in the order of DDTs > PCBs > HCHs > CHLs > HCB in both resident and migratory birds. Residue concentrations, according to the feeding habit, showed little variability, which may reflect relatively similar trophic levels of the bird species analyzed. Resident birds accumulated greater concentrations of DDTs as compared to migrants. In contrast, HCH residues were greater in migratory species. Higher proportions of p,p'-DDT to total DDT concentrations were found in many species of residents and migrants, indicating recent exposure to technical DDT in northern Vietnam. Congener-specific PCB analysis showed the predominance of penta- and hexachlorobiphenyls in all the species analyzed. Estimation of hepatic microsomal enzyme activities suggested higher metabolic capacity for PCB congeners in shore birds from Vietnam as compared to higher-trophic predator birds and marine mammals. Comparison of OC residues in avian species in Asia-Pacific revealed that DDT residues in resident birds in North Vietnam are among the highest values reported for the countries surveyed, suggesting recent usage of DDT in Vietnam. Available data for birds, fish, and bivalves from the recent Asia-Pacific Mussel Watch Program suggested that Vietnam might be a potential source of DDT contamination in Asian developing countries. To our knowledge, this is the first study of the OC accumulation in avian species from Vietnam.

Light pollution enhances ground‐level exposure to airborne toxic chemicals for nocturnally migrating passerines

“…For bird species that conduct seasonal migration, toxic chemical contamination can occur on the breeding or non‐breeding grounds or at stopover sites during migration. Migratory bird species have been found to have different types and concentrations of toxic chemicals between their breeding and non‐breeding grounds (Albert et al, 2021; Parolini et al, 2021) and when compared to resident species (Corsolini et al, 2011; Hong et al, 2014; Jin et al, 2016; Kunisue et al, 2003; Minh et al, 2002; Tanabe et al, 1998). These differences are a likely consequence of migratory species encountering different toxic chemical contamination profiles across their annual geographic distributions.…”