Biomagnification of naturally-produced methoxylated polybrominated diphenyl ethers (MeO-PBDEs) in harbour seals and harbour porpoises from the Southern North Sea

Harbour seals and harbour porpoises are top predator species from the North Sea, have long life spans and hence, are known to accumulate high levels of anthropogenic contaminants. To gain knowledge about the behaviour of naturally-produced compounds in these marine mammals, the biomagnification of naturally-produced methoxylated polybrominated diphenyl ethers (MeO-PBDEs) was assessed. The biomagnification of MeO-PBDEs (2′-MeO-BDE 68 and 6-MeO-BDE 47) was lower in harbour seals (all biomagnification factors (BMFs) < 1) compared to the same age–gender groups of the harbour porpoises (all BMFs > 1). This may indicate a better metabolic breakdown of MeO-PBDEs in harbour seals, as was previously suggested for polybrominated diphenyl ethers (PBDEs). In both predators, 6-MeO-BDE 47 had the highest concentrations (range: 45–483 ng/g lw and 2–38 ng/g lw for harbour porpoises and seals, respectively) compared to 2′-MeO-BDE 68 (range: 2–28 ng/g lw and 1–6 ng/g lw for harbour porpoises and seals, respectively). In general, the highest concentrations were found in juveniles, suggesting an increased biotransformation capacity with age or the influence of dilution by growth for both species. Here we show that naturally-produced brominated organic compounds can biomagnify and accumulate in North Sea top predators, although to a lesser extent than anthropogenic lipophilic contaminants, such as polychlorinated biphenyls (PCBs) or PBDEs.     

Effect of organochlorine contaminants and individual biological traits on blubber retinoid concentrations in bottlenose dolphins (Tursiops truncatus)

Here we assessed retinoids as biomarkers of contaminant exposure by studying whether the sex, age, lipid content and organochlorine concentrations of bottlenose dolphins induced variation in retinoid status and its deposition in blubber. Blubber samples were collected from 47 individuals of known age and gender from Sarasota Bay in June 2000 and 2001. The sample included a representative cross-section of the resident dolphin community, with ages ranging from 2 to 50 years. Organochlorine levels showed the age- and sex-related variation commonly observed in other species, with concentrations increasing in youngsters of both sexes and in adult males, and decreasing in adult females after the onset of maturity. Blubber lipid content was low in the overall population and significantly decreased with age in adult males. Retinoid blubber concentrations were comparable to other odontocete species previously studied, and were strongly determined by lipid content. As a consequence of the latter, retinoid concentration was observed to decrease with age in adult males. This effect could not be statistically dissociated from the negative correlation observed between levels of organochlorines and retinoid blubber concentration. Consequently, we could not clarify whether high organochlorine loads in this population lowered retinoid concentrations or, conversely, whether depleted lipid reserves were indeed responsible for the high organochlorine concentrations and the low retinoid levels detected in blubber. With the current knowledge, both options should be considered and investigated, with initial focus on male dolphins.     

Priority assessment of toxic substances in life cycle assessment. Part I: calculation of toxicity potentials for 181 substances with the nested multi-media fate, exposure and effects model USES-LCA

Toxicity potentials are standard values used in life cycle assessment (LCA) to enable a comparison of toxic impacts between substances. In most cases, toxicity potentials are calculated with multi-media fate models. Until now, unrealistic system settings were used for these calculations. The present paper outlines an improved model to calculate toxicity potentials: the global nested multi-media fate, exposure and effects model USES-LCA. It is based on the Uniform System for the Evaluation of Substances 2.0 (USES 2.0). USES-LCA was used to calculate for 181 substances toxicity potentials for the six impact categories freshwater aquatic ecotoxicity, marine aquatic ecotoxicity, freshwater sediment ecotoxicity, marine sediment ecotoxicity, terrestrial ecotoxicity and human toxicity, after initial emission to the compartments air, freshwater, seawater, industrial soil and agricultural soil, respectively. Differences of several orders of magnitude were found between the new toxicity potentials and those calculated previously.     

Comparison of the method of diffusive gels in thin films with conventional extraction techniques for evaluating zinc accumulation in plants and isopods

The measurement of diffusive gels in thin films (DGT) has recently been developed to assess metal bioavailability in soils. The DGT-method is based on diffusion in a porous matrix. To test the predictive capabilities of the method with regard to metal bioavailability, a study was set up with 28 soils having a variety of textures and amounts of zinc salts added. Correlation and regression analyses were performed to compare DGT-extracted zinc levels to zinc concentrations obtained by extraction with 0.01 M CaCl(2) and 0.43 M HNO(3), digestion with aqua regia and the zinc concentration in pore water. The amount of zinc extracted with CaCl(2) correlated well with DGT-extracted zinc levels in all soils spiked with different amounts of ZnCl(2). A similar correlation was not found for zinc concentrations in soil samples collected in the field. Experiments were performed to compare zinc content in organisms and in soils. The organisms tested were plants (grass, lettuce and lupine) and the hard bodied soil dwelling isopod Oniscus asellus. Good correlations were found between zinc accumulation in grass and lettuce and the C(E) (effective concentration) measured by a DGT-device, CaCl(2) extracted zinc and the zinc content in the pore water of all soils. The correlation with C(E) was not significant for lupine, neither for spiked soils, nor for field soils (p< or =0.001). Zinc levels in the isopods were not significantly related to any set of zinc measurements. From a synthesis of all results obtained it is concluded that the DGT-methodology does not have an additional value in predicting bioavailability of zinc in terrestrial ecosystems as compared to conventional extraction methods.     

Inter-species differences for polychlorinated biphenyls and polybrominated diphenyl ethers in marine top predators from the Southern North Sea: Part 2. Biomagnification in harbour seals and harbour porpoises

Harbour porpoises (Phocoena phocoena) and harbour seals (Phoca vitulina) were found to differ in the ability to metabolize polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). Biomagnification factors (BMFs), calculated between both predators and their prey (sole - Solea solea and whiting - Merlangius merlangus), had a large range of variation (between 0.5 and 91 for PCBs and between 0.6 and 53 for PBDEs). For the higher chlorinated PCBs and the highest brominated PBDEs, the BMF values in adult males were significantly higher than in the juvenile individuals of both species. BMF values of hexa- to octa-PCBs were the highest, suggesting reduced ability to degrade these congeners. Harbour porpoises had higher BMFs for lower chlorinated PCBs and for all PBDEs compared to harbour seals. Other factors, which may influence biomagnification, such as the octanol-water partition coefficients and the trophic level position measured through stable isotope (δ¹⁵N) analysis, were found to be of lesser importance to predict biomagnification in the studied food chain.     

Energy effects associated with e-commerce: a case-study concerning online sales of personal computers in The Netherlands

The introduction of e-commerce is changing purchase and distribution patterns dramatically. One of the observed effects is that logistics become more efficient as products are directly shipped from a manufacturer or wholesaler to an end-user. Another effect is that market transparency increases, which has a downward pressure on prices of many products sold via the Internet. This article addresses the energy implications of e-commerce at the micro level. This is done by quantifying the transport related energy savings in the case of a Dutch online computer reseller and by assessing the extra energy expenditure associated with increased buying power of online buyers. It is found that energy use per article sold by the online computer reseller is lower. However, taking into account indirect effects such as increased consumer buying power, there are scenarios that lead to an overall increase in energy use.     

Inter-species differences for polychlorinated biphenyls and polybrominated diphenyl ethers in marine top predators from the Southern North Sea: Part 1. Accumulation patterns in harbour seals and harbour porpoises

Harbour porpoises (Phocoena phocoena) and harbour seals (Phoca vitulina) are two representative top predator species of the North Sea ecosystem. The median values of sum of 21 polychlorinated biphenyl (PCB) congeners and sum of 10 polybrominated diphenyl ether (PBDE) congeners were 23.1 μg/g lipid weight (lw) and 0.33 μg/g lw in blubber of harbour seals (n = 28) and 12.4 μg/g lw and 0.76 μg/g lw in blubber of harbour porpoises (n = 35), respectively. For both species, the highest PCB concentrations were observed in adult males indicating bioaccumulation. On the contrary, the highest PBDE concentrations were measured in juveniles, likely due to better-developed metabolic capacities with age in adults. A higher contribution of lower chlorinated and non-persistent congeners, such as CB 52, CB 95, CB 101, and CB 149, together with higher contributions of other PBDE congeners than BDE 47, indicated that harbour porpoises are unable to metabolize these compounds. Harbour seals showed a higher ability to metabolize PCBs and PBDEs.