Bulk methods overestimate mercury biomagnification in marine food chains.
Compound-specific stable nitrogen isotope analysis of amino acids helps estimate food chain levels more accurately. By studying fish and birds in the Gulf of St. Lawrence, researchers found that traditional methods overestimate mercury biomagnification compared to CSIA-AA. The CSIA-AA equations showed lower trophic magnification factors (TMFs) of 10 to 19, while bulk stable isotope analysis had a TMF of 43. This suggests that using different methods can lead to discrepancies in assessing contaminant biomagnification.