Influence of Chemical and Biological Factors on Trophic Transfer of Persistent Organic Pollutants in the Northwater Polynya Marine Food Web

Abstract

Persistent organic pollutants (POPs) and stable isotopes of nitrogen (delta 15N) were measured in zooplankton (6 species), a benthic invertebrate (Anonyx nugax), Arctic cod (Boreogadus saida), seabirds (6 species), and ringed seals (Phoca hispida) collected in 1998 in the Northwater Polynya to examine effects of biological and chemical factors on trophic transfer of POPs in an Arctic marine food web. Strong positive relationships were found between recalcitrant POP concentrations (lipid corrected) and trophic level based on stable isotopes of nitrogen, providing clear evidence of POP biomagnification in Arctic marine food webs. Food web magnification factors (FWMFs), derived from the slope of the POP--trophic level relationship, provided an overall magnification factor for the food web but over and underestimated biomagnification factors (BMFs) based on predator--prey concentrations in poikilotherms (fish) and homeotherms (seabirds and mammals), respectively. Greater biomagnification in homeotherms was attributed to their greater energy requirement and subsequent feeding rates. Within the homeotherms, seabirds had greater BMFs than ringed seals, consistent with greater energy demands in birds. Scavenging from marine mammal carcasses and accumulation in more contaminated winter habitats were considered important variables in seabird BMFs. Metabolic differences between species resulted in lower than expected BMFs, which would not be recognized in whole food web trophic level--POP relationships. The use of sigma POP groups, such as sigma PCB, is problematic because FWMFs and BMFs varied considerably between individual POPs. FWMFs of recalcitrant POPs had a strong positive relationship with log octanol--water partition coefficient (Kow). Results of this study show the utility of using delta 15N to characterize trophic level and trophic transfer of POPs but highlight the effects of species and chemical differences on trophic transfer of POPs that can be overlooked when a single magnification factor is applied to an entire food web.

Why Do Organochlorine Differences between Arctic Regions Vary among Trophic Levels?

“…e DDTs is p,p′-DDE, p,p′-DDD, and p,p′-DDT for zooplankton and fish; p,p′-DDE for seabirds; and p,p′-DDE and p,p′-DDT for seals. and the recoveries were within acceptable ranges as described in previous publications (9,10,14,15,24,25,27).…”

“…Methods with modifications for extraction, cleanup, separation, identification, and quantification followed standard procedures and are described in previous publications (9,10,14,15,24,25,27). The participating laboratories' analytical quality has been confirmed by good results from international intercalibration tests (9,24). All NOW and CBS samples were analyzed on high-resolution gas chromatograph equipped with Ni-electron capture detector, except NOW ringed seals for which the gas chromatograph was equipped with a mass spectrometer detector.…”

Use of chemical tracers in assessing the diet and foraging regions of eastern North Pacific killer whales

“…Because each contaminant (or group of summed contaminants) is biomagnified to a different extent, contaminant ratios will also change as contaminants from prey are assimilated by the predator (Fisk et al, 2001;Hoekstra et al, 2003). However, biomagnification factors (BMFs) appear to be species-specific (Fisk et al, 2001;Hoekstra et al, 2003) and no BMFs have been reported for killer whales.…”

Avaliação de contaminação ambiental causada por poluentes orgânicos persistentes utilizando simulação computacional

“…Devido à toxicidade dos compostos, baixa degradação nas águas e fatores de bioacumulação (que eleva exponencialmente a contaminação em seres vivos devido à acumulação em tecidos adiposos), seres vivos expostos às águas contaminadas podem contaminar toda a cadeia alimentar, com níveis prejudiciais [12][13][14][15][16][17][18][19] . A simulação apontou que em 500 anos o meio ambiente não estará livre da contaminação por mirex e clordecona, devido à retenção dos poluentes no solo.…”