Characterization of Halogenated Organic Compounds in Pelagic Sharks and Sea Turtles Using a Nontargeted Approach

Area of Science:

• Environmental Chemistry
• Marine Biology
• Analytical Chemistry

Background:

• Marine species accumulate diverse halogenated organic compounds (HOCs).
• Understanding HOC profiles in apex predators and sea turtles is crucial for assessing ecosystem health.
• Previous studies often focused on targeted contaminants, potentially missing novel compounds.

Purpose of the Study:

• To analyze and compare HOC profiles in sharks and sea turtles from the Atlantic and Pacific Oceans.
• To identify and characterize novel or nontargeted HOCs (NHOCs) in these marine species.
• To assess the diversity and abundance of HOCs, including legacy contaminants and newly identified compounds.

Main Methods:

• Nontargeted analysis using two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GCxGC-HRTOFMS).
• Analysis of liver tissues from shortfin mako, porbeagle sharks, loggerhead, green, olive ridley, and hawksbill sea turtles.
• Identification and quantification of halogenated methoxyphenols (halo-MeOPs), polychlorinated biphenyls (PCBs), and other NHOCs.

Main Results:

• Sharks and sea turtles exhibited distinct HOC profiles.
• Halogenated methoxyphenols (halo-MeOPs) were dominant in sea turtles, while polychlorinated biphenyls (PCBs) were dominant in sharks.
• A total of 110 NHOCs were identified, with shortfin mako from the Gulf of Mexico showing the highest diversity and number of NHOCs. Specific C14H12-Cl compounds, chlorocarbazoles, and tris(chlorophenyl) methanes were abundant.

Conclusions:

• Nontargeted HOC analysis reveals significant differences in contaminant profiles between sharks and sea turtles.
• The discovery of numerous NHOCs underscores the complexity of marine pollution and the limitations of targeted analyses.
• Further research is needed to develop more complete chemical profiles of marine environments to understand the full scope of HOC contamination.