Nontargeted Screening of Halogenated Organic Compounds in Bottlenose Dolphins (Tursiops truncatus) from Rio de Janeiro, Brazil

Abstract

To catalog the diversity and abundance of halogenated organic compounds (HOCs) accumulating in high trophic marine species from the southwestern Atlantic Ocean, tissue from bottlenose dolphins (Tursiops truncatus) stranded or incidentally captured along the coast of Rio de Janeiro, Brazil, were analyzed by a nontargeted approach based on GC×GC/TOF-MS. A total of 158 individual HOCs from 32 different structural classes were detected in the blubber of 4 adult male T. truncatus. Nearly 90% of the detected compounds are not routinely monitored in the environment. DDT-related and mirex/dechlorane-related compounds were the most abundant classes of anthropogenic origin. Methoxy-brominated diphenyl ethers (MeO-BDEs) and chlorinated methyl- and dimethyl bipyrroles (MBPs and DMBPs) were the most abundant natural products. Reported for the first time in southwestern Atlantic cetaceans and in contrast to North American marine mammals, chlorinated MBPs and DMBPs were more abundant than their brominated and/or mixed halogenated counterparts. HOC profiles in coastal T. truncatus from Brazil and California revealed a distinct difference, with a higher abundance of MeO-BDEs, mirex/dechloranes and chlorinated bipyrroles in the Brazilian dolphins. Thirty-six percent of the detected HOCs had an unknown structure. These results suggest broad geographical differences in the patterns of bioaccumulative chemicals found in the marine environment and indicate the need to develop more complete catalogs of HOCs from various marine environments.

Figure 1.

Relative abundance of HOCs by chemical class detected in the blubber of adult male bottlenose dolphins (T. truncatus) from the Rio de Janeiro coast, Brazil. Symbols represent individual samples (n=4) and the dash represents the median. –M, –U and –N refer to mixed, unknown and natural sources, respectively. The acronyms are listed in the SI.

Figure 2.

Relative abundance of naturally occurring HOCs detected in the blubber of adult male bottlenose dolphins (T. truncatus) from the Rio de Janeiro coast, Brazil. The acronyms are listed in the SI.

Figure 3.

Relative abundance of the anthropogenic HOCs detected in adult male bottlenose dolphins (T. truncatus) from Rio de Janeiro, Brazil. Circles represent individual samples (n=4) and the dash represents the median.

Figure 4.

Electron ionization mass spectra of a) Unknown-15, b) Unknown-21, and c) Unknown-33

Figure 5.

Biplot of the NE Pacific (California Bight) and SW Atlantic (Rio de Janeiro Coast) contaminant profiles. The cumulative proportion of the variance represented by principal component 1 (PC1) and PC2 was 60% and 74%, respectively. Dolphin groups were separated primarily along PC1. The arrows show the relative loadings (influence) of contaminants on the first and second principal components. The five largest negative loadings and five largest positive loading on PC1 are shown and discussed in the text. 1 = o,p’-DDD, 2 = 4,4’dichlorobenzophenone, 3 = TCPM, 4 = DDMU-3, 5 = TCPM-1, 6 = 6-MeO-BDE-47, 7 = unknown-15, 8 = 2’-MeO-BDE-68, 9 = MBP-Cl₇, 10 = mirex. Negative loadings indicate relatively high contaminant abundance in the NE Pacific samples, and positive loadings indicate relatively high contaminant abundance in the SW Atlantic samples. The assignment of dolphin samples to each PCA cluster was confirmed by k-means analysis.