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81.
Levels and temporal trends of the hexachlorocyclohexane isomers alpha-, beta- and gamma-HCH were analysed in blubber of juvenile ringed seals from West Greenland (1994 to 2006) and juvenile and adult ringed seals from East Greenland (1986 to 2006). No significant differences in the concentration levels in the juvenile seals were found between East and West Greenland for any of the three isomers. alpha-HCH concentrations were not significantly different between juvenile and adult ringed seals from East Greenland, whereas beta- and gamma-HCH concentrations were significantly higher in adult ringed seals. alpha- and beta-HCH in Greenland ringed seals were approximately a factor two lower than in the Canadian Arctic, and alpha-HCH was a factor 2-3 higher than in ringed seals from an area east of Svalbard, Norway. Annual decreases in ringed seals from Greenland during the study periods were detected to be 9.1-11.7%, 1.4-3.9% and 6.0-6.4% for alpha-, beta- and gamma-HCH, respectively, being quite similar in both East and West Greenland. Similar levels and trends in East and West Greenland support the general understanding of the pathways of HCH isomers to and in the Arctic.  相似文献   
82.
Extensive screening analyses of perfluorooctane sulfonate (PFOS) and related perfluorinated compounds in biota samples from all over the world have identified PFOS as a global pollutant and have shown its bioaccumulation into higher trophic levels in the food chain. Perfluorinated compounds have been found in remote areas as the Arctic. In this study a preliminary screening of PFOS and related compounds has been performed in liver samples of fish, birds and marine mammals from Greenland and the Faroe Islands. PFOS was the predominant fluorochemical in the biota analyzed, followed by perfluorooctane sulfonamide (PFOSA). PFOS was found at concentrations above LOQ (10 ng/g wet weight) in 13 out of 16 samples from Greenland and in all samples from the Faroe Islands. The results from Greenland showed a biomagnification of PFOS along the marine food chain (shorthorn sculpin < ringed seal < polar bear). The greatest concentration of PFOS was found in liver of polar bear from east Greenland (mean: 1285 ng/g wet weight, n = 2). The geographical distribution of perfluorinated compounds in Greenland was similar to that of persistent organohalogenated compounds (OHCs), with the highest concentrations in east Greenland, indicating a similar geographical distribution to that of OHCs, with higher concentrations in east Greenland than in west Greenland.  相似文献   
83.
This study assessed the effect of temperature and thermal atmospheric conditions on all-cause and cardiovascular mortality in Bangladesh. In particular, differences in the response to elevated temperatures between urban and rural areas were investigated. Generalized additive models (GAMs) for daily death counts, adjusted for trend, season, day of the month and age were separately fitted for urban and rural areas. Breakpoint models were applied for determining the increase in mortality above and below a threshold (equivalent) temperature. Generally, a 'V'-shaped (equivalent) temperature-mortality curve with increasing mortality at low and high temperatures was observed. Particularly, urban areas suffered from heat-related mortality with a steep increase above a specific threshold. This adverse heat effect may well increase with ongoing urbanization and the intensification of the urban heat island due to the densification of building structures. Moreover, rising temperatures due to climate change could aggravate thermal stress.  相似文献   
84.
By mainly targeting larger predatory fish, commercial fisheries have indirectly promoted rapid increases in densities of their prey; smaller predatory fish like sprat, stickleback and gobies. This process, known as mesopredator release, has effectively transformed many marine offshore basins into mesopredator-dominated ecosystems. In this article, we discuss recent indications of trophic cascades on the Atlantic and Baltic coasts of Sweden, where increased abundances of mesopredatory fish are linked to increased nearshore production and biomass of ephemeral algae. Based on synthesis of monitoring data, we suggest that offshore exploitation of larger predatory fish has contributed to the increase in mesopredator fish also along the coasts, with indirect negative effects on important benthic habitats and coastal water quality. The results emphasize the need to rebuild offshore and coastal populations of larger predatory fish to levels where they regain their control over lower trophic levels and important links between offshore and coastal systems are restored.  相似文献   
85.
Recently, we reported on soil fate of SDZ residues amended with pig manure treated with 1?C-labeled sulfadiazine 1?C-SDZ). The first objective of the present study was to determine whether this strategy can be substituted by application of 1?C-SDZ to soil. The second objective was to characterize non-extractable SDZ residues by fractionation, size exclusion chromatography (SEC) and solid state 13C-NMR. The fate of 1?C-SDZ was examined for 28 d, using two soils with and without amendment of pig manure. Mineralization of 1?C-SDZ was low; extractable residues decreased to 7-30%. Compared to the previous study, results were similar. 1?C-SDZ derived bound radioactivity was found in HCl-washings, fulvic, humic acids and humin. According to SEC, one bound 1?C portion (70%) co-eluted with fulvic acids (above 910 g mol?1); the other consisted of adsorbed/entrapped 1?C-SDZ. The 13C-SDZ study was performed for 30 d; humic acids were examined by 13C-NMR. A signal (100-150 ppm) was referred to 13C-SDZ. SEC and 13C-NMR demonstrated rapid integration of SDZ into humics.  相似文献   
86.
87.
Programs and projects employing payments for ecosystem service (PES) interventions achieve their objectives by linking buyers and sellers of ecosystem services. Although PES projects are popular conservation and development interventions, little is known about their adherence to basic ecological principles. We conducted a quantitative assessment of the degree to which a global set of PES projects adhered to four ecological principles that are basic scientific considerations for any project focused on ecosystem management: collection of baseline data, identification of threats to an ecosystem service, monitoring, and attention to ecosystem dynamics or the formation of an adaptive management plan. We evaluated 118 PES projects in three markets—biodiversity, carbon, and water—compiled using websites of major conservation organizations; ecology, economic, and climate‐change databases; and three scholarly databases (ISI Web of Knowledge, Web of Science, and Google Scholar). To assess adherence to ecological principles, we constructed two scientific indices (one additive [ASI] and one multiplicative [MSI]) based on our four ecological criteria and analyzed index scores by relevant project characteristics (e.g., sector, buyer, seller). Carbon‐sector projects had higher ASI values (P < 0.05) than water‐sector projects and marginally higher ASI scores (P < 0.1) than biodiversity‐sector projects, demonstrating their greater adherence to ecological principles. Projects financed by public–private partnerships had significantly higher ASI values than projects financed by governments (P < 0.05) and marginally higher ASI values than those funded by private entities (P < 0.1). We did not detect differences in adherence to ecological principles based on the inclusion of cobenefits, the spatial extent of a project, or the size of a project's budget. These findings suggest, at this critical phase in the rapid growth of PES projects, that fundamental ecological principles should be considered more carefully in PES project design and implementation in an effort to ensure PES project viability and sustainability.  相似文献   
88.
Animal‐mediated seed dispersal is important for sustaining biological diversity in forest ecosystems, particularly in the tropics. Forest fragmentation, hunting, and selective logging modify forests in myriad ways and their effects on animal‐mediated seed dispersal have been examined in many case studies. However, the overall effects of different types of human disturbance on animal‐mediated seed dispersal are still unknown. We identified 35 articles that provided 83 comparisons of animal‐mediated seed dispersal between disturbed and undisturbed forests; all comparisons except one were conducted in tropical or subtropical ecosystems. We assessed the effects of forest fragmentation, hunting, and selective logging on seed dispersal of fleshy‐fruited tree species. We carried out a meta‐analysis to test whether forest fragmentation, hunting, and selective logging affected 3 components of animal‐mediated seed dispersal: frugivore visitation rate, number of seeds removed, and distance of seed dispersal. Forest fragmentation, hunting, and selective logging did not affect visitation rate and were marginally associated with a reduction in seed‐dispersal distance. Hunting and selective logging, but not fragmentation, were associated with a large reduction in the number of seeds removed. Fewer seeds of large‐seeded than of small‐seeded tree species were removed in hunted or selectively logged forests. A plausible explanation for the consistently negative effects of hunting and selective logging on large‐seeded plant species is that large frugivores, as the predominant seed dispersers for large‐seeded plant species, are the first animals to be extirpated from hunted or logged forests. The reduction in forest area after fragmentation appeared to have weaker effects on frugivore communities and animal‐mediated seed dispersal than hunting and selective logging. The differential effects of hunting and selective logging on large‐ and small‐seeded tree species underpinned case studies that showed disrupted plant‐frugivore interactions could trigger a homogenization of seed traits in tree communities in hunted or logged tropical forests. Meta Análisis de los Efectos de la Perturbación Humana sobre la Dispersión de Semillas por Animales  相似文献   
89.
90.
Tradable permit markets have become an increasingly popular tool to address environmental policy problems. This paper describes and evaluates the performance of the Regional Clean Air Incentives Market (RECLAIM) that started operating in Southern California at the beginning of 1994. In analysing overall market performance as well as industry and firm specific information,we find strong evidence for uncertainty influencing market participation during the first two years. Furthermore we find evidence for flexibility-induced abatement cost savings as well as a potential business cycle effect on trading behaviour.Our findings emphasizethe importanceof institutional features of trading programmes.  相似文献   
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