992 resultados para environmental concentrations
Resumo:
We assessed the relationship between exposure to organohalogen polluted minke whale (Balaenoptera acutorostrata) blubber and liver morphology and function in a generational controlled study of 28 Greenland sledge dogs (Canis familiaris). The prevalence of portal fibrosis, mild bile duct hyperplasia, and vascular leukocyte infiltrations was significantly higher in the exposed group (all Chi-square: p<0.05). In case of granulomas, the frequency was significantly highest in the bitches (P generation) while the prevalence of portal fibrosis was highest in the F generation (pups) (both Chi-square: p<0.05). No significant difference between exposed and controls was found for bile acid, ALAT, and ALKP, while ASAT and LDH were significantly highest in the control group (both ANOVA: p<0.05). We therefore suggest that a daily intake of 50-200 g environmentally organohalogen polluted minke whale blubber can cause liver lesions in Greenland sledge dogs. It is reasonable to infer that other apex predators such as polar bears (Ursus maritimus) and humans may suffer from similar impacts.
Resumo:
Distributions of Fe, Mn, Zn, Cu, Ni, Co, Cr, Pb, As, Ag, Cd, Se, Sb, and Hg in 128 samples of tissues of organisms that inhabit hydrothermal vent fields of the Mid-Atlantic Ridge (Menez Gwen, Snake Pit, and Rainbow) depending on the abiotic environmental parameters were studied. The majority of the elements studied showed direct correlations between their concentrations in fluids released and in tissues of hydrothermal organisms. A higher degree of bioaccumulation of metals was revealed in Bathymodiolus mussels and Rimicaris shrimps from the Rainbow hydrothermal vent field as compared to their analogues from the Menez Gwen and Snake Pit fields. This corresponds to maximal concentrations of the majority of the metals studied in the Rainbow high-temperature hydrothermal fluids. The highest degree of bioaccumulation of heavy metals was found in gills of symbiotrophic mussels Bathymodiolus and in maxillipeds of ectosymbiotic shrimps Rimicaris, i.e., in organs that function in dependence on chemosynthetic bacteria. Within the Rainbow vent field, the shrimps, which inhabit in biotopes with more high-temperature conditions and therefore are more strongly subjected to influence of fluids, were found to contain higher metal contents than mollusks. Fe-Mn hydroxide films that cover mussel shells might serve as important reservoirs of other metals related to Fe and Mn.
Resumo:
We used holes augered partially into first-year sea ice (sumps) to determine a- and g-HCH concentrations in sea-ice brine. The overwintering of the CCGS Amundsen in the Canadian western Arctic, as part of the Circumpolar Flaw Lead (CFL) System Study, provided the circumstances to allow brine to accumulate in sumps sufficiently to test the methodology. We show, for the first time, that as much as 50% of total HCHs in seawater can become entrapped within the ice crystal matrix. On average, in the winter first-year sea ice HCH brine concentrations reached 4.013 ± 0.307 ng/L and 0.423 ± 0.013 ng/L for the a- and g-isomer, respectively. In the spring, HCHs decreased gradually with time, with increasing brine volume fraction and decreasing brine salinity. These decreasing concentrations could be accounted for by both the dilution with the ice crystal matrix and under-ice seawater. We propose that the former process plays a more significant role considering brine volume fractions calculated in this study were below 20%. Levels of HCHs in the brine exceed under-ice water concentrations by approximately a factor of 3, a circumstance suggesting that the brine ecosystem has been, and continues to be, the most exposed to HCHs.