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81.
Nizzetto L Stroppiana D Brivio PA Boschetti M Di Guardo A 《Journal of environmental monitoring : JEM》2007,9(6):542-549
Forests were shown to play an important role in influencing atmospheric concentrations and transport of persistent organic pollutants (POPs) in the environment. World forests cover more than 4 billion hectares and contain up to 80% of the above ground organic carbon. Given the lipophilic nature of POPs, this suggests that forests can influence the environmental fate of POPs at a global scale. POP accumulation in forest canopies still presents points of concern given the complexity of these ecosystems. In particular, the role of ecological parameters such as LAI (leaf area index) and SLA (specific leaf area) and their dynamics during the growing season was not sufficiently investigated yet. This paper reviews, compares and interprets a unique case study in which air and leaf concentrations and deposition fluxes for selected polychlorinated biphenyls (PCBs) were measured in three different forest types exposed to the same air masses. In order to trace the air-leaf-soil path of these compounds, a dynamic model of POP accumulation into forest canopy was applied. The dynamics of the canopy biomass strongly affected the trend of leaf concentration with time. Growth dilution effect can prevent the more chlorinated compounds from reaching the partitioning equilibrium before litter fall, while the more volatile compounds can approach equilibrium in the range of few weeks. An amount of up to 60 ng of PCBs per square metre of ground surface was predicted to be stored in each of the selected forests at fully developed canopy. Dry gaseous deposition fluxes to forest canopy were estimated to reach a maximum value of about 0.5-1.5 ng m(-2) d(-1) during the spring period. 相似文献
82.
83.
Patrizia Jereb Rita Cannas Porzia Maiorano Giambattista Bello Fulvio Garibaldi Marco Mereu Francesco G. Ancona Giovanni Ammendolia Pietro Battaglia Önder Duysak Hendrik Jan T. Hoving Eugenia Lefkaditou Marek R. Lipinski Riccardo Melis Panagiota N. Peristeraki Sergio Ragonese Teresa Romeo Alp Salman Begonia M. Santos Alberto Villari Danila Cuccu 《Marine Biology》2016,163(9):192
84.
Lake Temsah is one of the main wetlands in the Suez Canal region, and the main source for fish for the area. The lake is the end-point of several wastewater effluents. In the present study, residues of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyl (PCB) and polycyclic aromatic hydrocarbons (PAH) were monitored in the sediment of the lake. Samples were collected from six different sampling stations around the lake using a box-corer sampler, then kept frozen. Samples were extracted and cleaned up before residue determination was conducted using an HRGC/HRMS. An HP 6890 plus gas chromatograph was coupled to a Micromass Autospec Ultima mass spectrometer operating in EI mode at 35 eV and with a resolution of 10.000 (5% valley). PCDDs and PCDFs were detected in all sediment samples collected from various sampling stations. Results showed some progressive increase in PCDDs concentrations relevant to increase in chlorination. In the PCDD group of congeners, 1, 2, 3, 4, 6, 7, 8, 9 octa-CDD had the highest detected concentrations in all samples, while 2, 3, 7, 8 tetra-CDD showed the lowest concentrations. The World Health Organization toxicity equivalents ranged from 0.387 to 11.20 ng kg?1 d.w. For PCDD homologues, hexa-CDD was the most dominant homologue in all sediment samples analysed. Regarding dioxin-like PCBs, results showed that IUPAC No. 118 congener, 2, 3, 4, 4, 5, pentachlorobiphenyl was the most concentrated of all detected congeners, with concentrations ranging between 0.039 and 43.201 µg kg?1. For polycyclic aromatic hydrocarbons, benzo(b+k+j)fluoranthene had the highest concentrations in almost all sampling stations. However, fluorene was the smallest detected concentration in almost all stations. This result would indicate that PAH contamination of the lake seems to be coming from one main source in all sampling stations. The present work is the first record of PCCDs, PCCFs, and dioxin-like PCBs in the Temsah lake. The concentrations of the contaminants monitored in this study, especially those of PAHs, are rather alarming. Efforts should be made to stop point sources that contaminate the lake. 相似文献
85.
This paper studies the effects of a tax on energy use in a growth model where market structure is endogenous and jointly determined with the rate of technological change. Because this economy does not exhibit the scale effect (a positive relation between TFP growth and aggregate R&D), the tax has no effect on the steady-state growth rate. It has, however, important transitional effects that give rise to surprising results. Specifically, under the plausible assumption that energy demand is inelastic, there may exist a hump-shaped relation between the energy tax and welfare. This shape stems from the fact that the reallocation of resources from energy production to manufacturing triggers a temporary acceleration of TFP growth that generates a √-shaped time profile of consumption. If endogenous technological change raises consumption sufficiently fast and by a sufficient amount in the long run, and households are sufficiently patient, the tax raises welfare despite the fact that—in line with standard intuition—it lowers consumption in the short run. 相似文献
86.
Nicola Bianchi Nicola Baccetti Claudio Leonzio Pietro Giovacchini 《Chemistry and Ecology》2018,34(7):595-609
In this study, we determined mercury and selenium levels in abandoned unhatched eggs of the yellow-legged gull (Larus michahellis) and Audouin’s gull (Larus audouinii) collected during 2004–2005 from the Tuscan archipelago and Sardinia (Italy). The different feeding habits of the two species probably determine the different uptakes of trace elements, as the study shows highly significant differences for selenium and mercury levels as well as shell thickness and Hg:Se molar ratio values. Audouin’s gulls nesting on the coasts of the Tuscan archipelago showed significantly higher selenium levels than did gulls from colonies from the islands around Sardinia. Comparisons with a similar investigation previously conducted in the same area suggested that mercury and selenium concentrations, although in line with reports in the literature, were significantly lower than levels encountered in gulls in the early 1980s. Mercury (mg/kg d.w.) dropped from 8.631 to 5.030 in Audouin’s gulls and from 2.509 to 0.828 in yellow-legged gulls. The regional decline in mercury levels following reduced use of the metal in industry and the probable food depletion effects linked to the overfishing of fish prey of these two gull species are discussed as hypotheses that could explain the decrease in mercury levels found in eggs. 相似文献
87.
Isabella Fabietti Giulia Grassini Sara Savelli Roberta Vicario Anita Romiti Milena Viggiano Chiara Vassallo Laura Valfrè Paola Giliberti Irma Capolupo Marco Bonito Pietro Bagolan Francesco Morini Leonardo Caforio 《黑龙江环境通报》2023,43(8):1002-1007