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181.
This geochemical study is focused on the easternmost part of the Po River alluvial plain in Northern Italy, which is interested by widespread agricultural activities, investigating a reclaimed sector of the Province of Ferrara, known as “Valle del Mezzano” (Mezzano Low Land, hereafter reported as MLL) characterized by peat-rich soils. The chemical–mineralogical characterization of these reclaimed soils is important to compare the local geochemical backgrounds with those recorded in other sectors of the River Po plain and to monitor if the observed concentration exceeds critical thresholds. The reported analyses include (a) measurement of the soil salinity, (b) nutrient evaluation, (c) major and trace element concentrations carried out on bulk soils, (d) tests of metal extraction with both aqua regia and EDTA to highlight the distinct elemental mobility and (e) phyto-toxicological measurement of heavy metal concentrations in plants (Lactuca sativa acephala) grown on the studied soils. The results indicate (1) high soil salinity, often with drastic increase of sodium and chloride along the soil profiles, (2) high nitrogen content (in part related to anthropogenic activities) on superficial horizons and nitrate decrease along the soil profiles and (3) comparative enrichments in heavy metals with respect to other soils of the province, which indicate that peat deposits are effective in trapping metals from anthropogenic sources. This, in turn, implies potential geochemical risks for the agricultural activities. In this regard, specific concerns are related to the high nickel and arsenic content of MLL soils due to the mobility of these elements and their attitude to be taken up by plants.  相似文献   
182.
Following the ratification of the Kyoto Protocol, afforestation of formerly arable lands and/or degraded areas has been acknowledged as a land-use change contributing to the mitigation of increasing atmospheric CO(2) concentration in the atmosphere. In the present work, we study the soil organic carbon sequestration (SOCS) in 21 year old stands of maple (Acer velutinum Bioss.), oak (Quercus castaneifolia C.A. Mey.), and red pine (Pinus brutia Ten.) in the Darab Kola region, north of Iran. Soil samples were collected at four different depths (0-10, 10-20, 20-30, and 30-40 cm), and characterized with respect to bulk density, water content, electrical conductivity, pH, texture, lime content, total organic C, total N, and earthworm density and biomass. Data showed that afforested stands significantly affected soil characteristics, also raising SOCS phenomena, with values of 163.3, 120.6, and 102.1 Mg C ha(-1) for red pine, oak and maple stands, respectively, vs. 83.0 Mg C ha(-1) for the control region. Even if the dynamics of organic matter (OM) in soil is very complex and affected by several pedo-climatic factors, a stepwise regression method indicates that SOCS values in the studied area could be predicted using the following parameters, i.e., sand, clay, lime, and total N contents, and C/N ratio. In particular, although the chemical and physical stabilization capacity of organic C by soil is believed to be mainly governed by clay content, regression analysis showed a positive correlation between SOCS and sand (R = 0.86(**)), whereas a negative correlation with clay (R = -0.77(**)) was observed, thus suggesting that most of this organic C occurs as particulate OM instead of mineral-associated OM. Although the proposed models do not take into account possible changes due to natural and anthropogenic processes, they represent a simple way that could be used to evaluate and/or monitor the potential of each forest plantation in immobilizing organic C in soil (thus reducing atmospheric C concentration), as well as to select more appropriate species during forestation plan management at least in the north of Iran.  相似文献   
183.
Territorial indicators based on the satellite measured reflected or emitted energy can provide valuable information on the spatial evolution of a territory. Information regarding land use, biomass coverage and radiant temperature were obtained from remotely obtained measurements for each municipality in the Province of Siena. Remotely sensed data were combined into different indices to compare characteristics of land cover between territories and create an information base for continued study. A classification was performed on a municipal level and land use classes were grouped together and a general index of use pressure was created. A vegetation index was used to compare biomass densities. A radiant temperature index was calculated using measure thermal infrared emissions. The results of these analyses allowed researchers to examine the intra and inter-municipal spatial heterogeneity within the Province. A comparison between the results of each index was made and the problems related to the use of such indices were examined.  相似文献   
184.
Guzzella L  Roscioli C  Binelli A 《Chemosphere》2008,73(10):1684-1691
Polybrominated diphenyl ethers (PBDEs) are characterized by chemical properties and toxicological profiles similar to other POPs (persistent organic pollutants) included in the EU Priority Pollutant List (2455/01/CE). However, limited data have been available for these compounds thus far for Italian freshwater abiotic matrices. Lake Maggiore basin, a heavily industrialized and densely populated area, was selected for studying PBDE contamination in Italy. PBDEs and OCs (organochlorine compounds) in the basin were quantified by analysing both sediment cores collected in 2005 from the lake and grab samples from the main tributaries and the emissary. Fourteen PBDEs, from tri-BDE to hepta-BDE congeners and BDE209, were compared with some organochlorine POPs (PCBs and DDTs) characterizing Lake Maggiore basin contamination. Analyses of tri-to hepta-BDEs, PCBs and DDTs were undertaken by GC-MS/MS, while BDE-209 was analysed by GC/ECD. Results showed a dominant presence of BDE-209 (>95% of SigmaBDE) and limited amounts of BDE-47, BDE-99, BDE-100, BDE-153 and BDE-154. Lake core profiles highlighted a decreasing trend in PCB concentrations starting from the year 2000, while PBDEs showed greater concentrations after the beginning of the 1990s (up to 30 ng g(-1)d.w.). Among the tributaries, the Bardello and Boesio rivers were the most PBDE-contaminated (up to 290 ng g(-1)d.w.).  相似文献   
185.
Recently, environmentally conscious design and extended producer responsibility have become key aspects for companies that need to develop products that are sustainable along their whole life cycle. Design for End of Life (EoL) is a strategy that aims to reduce landfill waste through the implementation of closed-loop product life cycles. It is important to consider disassembly and EoL scenario management as early as the design phase. For these reasons, this paper presents an approach to help designers in the evaluation and subsequent improvement in product EoL performance. The method is based on four innovative EoL indices that compare different EoL scenarios for each product component. In this way, the designer can modify the product structure or the liaisons to maximise the reuse and remanufacture of components as well as material recycling. The presented case studies confirm the validity of the approach in helping designers during the redesign phase of goods and products to reduce the quantity of materials and industrial wastes sent to landfill.  相似文献   
186.
Mitigation of infectious wildlife diseases is especially challenging where pathogens affect communities of multiple host species. Although most ecological studies recognize the challenge posed by multiple-species pathogens, the implications for management are typically assessed only qualitatively. Translating the intuitive understanding that multiple host species are important into practice requires a quantitative assessment of whether and how secondary host species should also be targeted by management and the effort this will require. Using a multiple-species compartmental model, we determined analytically whether and how intensively secondary host species should be managed to prevent outbreaks in focal hosts based on the reproduction number of individual host species and between-species transmission rates. We applied the model to the invasive pathogenic fungus Batrachochytrium salamandrivorans in a 2-host system in northern Europe. Avoiding a disease outbreak in the focal host (fire salamanders [Salamandra salamandra]) was impossible unless management also heavily targeted the secondary host (alpine newts [Ichthyosaura alpestris]). Preventing an outbreak in the community required targeted removal of at least 80% of each species. This proportion increased to 90% in the presence of an environmental reservoir of B. salamandrivorans and when the proportion of individuals removed could not be adjusted for different host species (e.g., when using traps that are not species specific). We recommend the focus of disease-mitigation plans should shift from focal species to the community level and calculate explicitly the management efforts required on secondary host species to move beyond the simple intuitive understanding that multiple host species may all influence the system. Failure to do so may lead to underestimating the magnitude of the effort required and ultimately to suboptimal or futile management attempts.  相似文献   
187.
Regional Environmental Change - Agroecosystems are facing a global challenge amidst a socioecological transition that places them in a dilemma between increasing land-use intensity to meet the...  相似文献   
188.
The aim of this study was to compare transplacental with non-transplacental amniocentesis in terms of related complications. Between January 1991 and December 1992, 4564 genetic amniocenteses were performed in 4527 patients (4491 singleton, 35 twin, and one triplet pregnancy) at 15–16 weeks of gestation. All the procedures were ultrasound-guided and performed by the same operator. In 1487 cases, an anterior placenta was traversed with the needle, whereas in 3077 cases, the needle was inserted directly into the amniotic cavity without traversing the placenta. After the exclusion of patients in whom amniotic cell culture failed or in whom an abnormal karyotype was obtained, and of patients lost to follow-up, a total of 4454 patients (98 per cent) were followed for 30 days after amniocentesis. Two spontaneous abortions occurred after a transplacental procedure, and five after a non-transplacental procedure (P = not significant). There were no episodes of amniotic fluid leakage in the first group, whereas 16 ruptures of the membranes that resolved spontaneously occurred in the second group (P<0·01). Our data suggest that transplacental amniocentesis carries a similar abortive risk to and a lower risk of transient rupture of the membranes than non-transplacental amniocentesis and may therefore be preferred at the gestational period examined (15–16 weeks). However, the risk of feto-maternal haemorrhage, which is reported to be higher for a transplacental procedure, must be considered in the case of an anterior placenta.  相似文献   
189.
We show that the degradation of phenol by Fe(III) and hydrogen peroxide is faster in the presence of humic acids. This is most likely due to faster reduction of Fe(III)-humate complexes by H2O2/HO2·/O2–· when compared with Fe(III)-H2O complexes. The fact that humic acids, a major class of naturally occurring compounds, favour the Fenton reaction has great relevance in the field of water and soil decontamination, where organic compounds usually have a negative effect. Furthermore, it adds insight into the self-depuration processes of natural aquifers.  相似文献   
190.
Restoration of habitats impacted by invasive plants is becoming an increasingly important tool in the management of native biodiversity, though most studies do not go beyond monitoring the abundance of particular taxonomic groups, such as the return of native vegetation. Yet, the reestablishment of trophic interactions among organisms in restored habitats is equally important if we are to monitor and understand how ecosystems recover. This study examined whether food web interactions among arthropods (as inferred by abundance of naturally occurring stable isotopes of C [delta13C] and N [delta15N]) were reestablished in the restoration of a coastal Spartina alterniflora salt marsh that had been invaded by Phragmites australis. From patterns of C and N stable isotopes we infer that trophic interactions among arthropods in the native salt marsh habitats are characterized by reliance on the dominant marsh plant Spartina as a basal resource. Herbivores such as delphacid planthoppers and mirid bugs have isotope signatures characteristic of Spartina, and predatory arthropods such as dolicopodid flies and spiders likewise have delta13C and delta15N signatures typical of Spartina-derived resources (approximately -13 per thousand and 10 per thousand, respectively). Stable isotope patterns also suggest that the invasion of Phragmites into salt marshes and displacement of Spartina significantly alter arthropod food web interactions. Arthropods in Phragmites-dominated sites have delta13C isotope values between -18 per thousand and -20 per thousand, suggesting reliance on detritus and/or benthic microalgae as basal resources and not on Phragmites, which has a delta13C approximately -26 per thousand. Since most Phragmites herbivores are either feeding internally or are rare transients from nearby Spartina, these resources do not provide significant prey resources for other arthropod consumers. Rather, predator isotope signatures in the invaded habitats indicate dependence on detritus/algae as basal resources instead of the dominant vegetation. The reestablishment of Spartina after removal of Phragmites, however, not only returned species assemblages typical of reference (uninvaded) Spartina, but stable isotope signatures suggest that the trophic interactions among the arthropods were also similar in reestablished habitats. Specifically, both herbivores and predators showed characteristic Spartina signatures, suggesting the return of the original grazer-based food web structure in the restored habitats.  相似文献   
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