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191.
Patrizia Sadocco Silvia Nocerino Ernestina Dubini-Paglia Alberto Seves Graziano Elegir 《Journal of Polymers and the Environment》1997,5(1):57-65
An extracellular poly(3-hydroxybutyrate) (PHB) depolymerase was purified fromAureobacterium saperdae cultural medium by using hydrophobic interaction chromatography. The isolated enzyme was composed of a single polypeptide
chain with a molecular mass of 42.7 kDa as determined by SDS-PAGE and by native gel filtration on TSK-HW-55S. The enzyme was
not a glycoprotein. Its optimum activity occurred at pH 8.0 and it showed a broad pH stability, ranging from pH 3 to pH 11.N-Bromosuccinamide and 2-hydroxy-5-nitrobenzyl bromide completely inactivated the enzyme, suggesting the involvement of tryptophan
residues at the active site of the protein. The enzyme was very sensitive to diisopropyl fluorophosphate and diazo-dl-norleucine methyl ester, showing the importance of serine and carboxyl groups. The modification of cysteine residues byp-hydroxy mercuricbenzoate did not cause a loss of activity, whereas dithiothreitol rapidly inactivated the enzyme, revealing
the presence of disulfide bonds.A saperdae depolymerase acted on the surface layer of PHB films and the degradation proceeded by surface erosion releasing monomers
and dimers of 3-hydroxybutric acid. The degradation of PHB films byA. saperdae depolymerase was partially inhibited in the presence of excess amounts of enzyme. This phenomenon, already observed by Mukaiet al. with poly(hydroxyalkanoates) depolymerases fromAlcaligenes faecalis, Pseudomonas pickettii, andComamonas testosteroni, was analyzed according to the kinetic model proposed by these authors. The experimental data evidenced a general agreement
with the kinetic model, although higher initial degradation rates were found withA. saperdae depolymerase. 相似文献
192.
Alberto Modelli Barbara Calcagno Mariastella Scandola 《Journal of Polymers and the Environment》1999,7(2):109-116
The standard test method ASTM D 5988-96 for determining the degree and rate of aerobic biodegradation of plastic materials in contact with soil was applied to poly(3-hydroxybutyrate) and poly(-caprolactone). The method proved to be reliable and supplied reproducible measurements of CO2 production, provided potassium (instead of barium) hydroxide was used as a trapping solution. The trends of CO2 evolution, as a function of time, observed for the degradation of polymer powders in soil are similar to those predicted by simple first order kinetics in solution. The experimental data are described by a Michaelis–Menten type model, which accounts for the heterogeneity of the polymer-soil system. The kinetic equation deduced predicts the degradation rate to the proportional to the exposed polymer surface area. 相似文献
193.
Mercury mining was a large and thriving industry during the last century in Asturias (NW Spain). At Bra?alamosa, mining activity introduced significant quantities of wastes in spoil heaps located close to the mining operations. In these mining wastes, in addition to mercury, high concentrations of other potentially dangerous elements like As have been found. As a consequence, pollution and dereliction of the local environment occurred. This paper focuses on the environmental impact of these old mining operations and describes a preliminary assessment of the extent of contamination. This includes analytical data from systematic sampling of soils, stream sediments, wastes from spoil heaps, water and herbaceous plants in areas affected by mining activities. The potential risk that spoil materials imply for human health and the environment is documented on the basis of the application of EPA Risk Assessment methodology. 相似文献
194.
Can machines recognise stress in plants? 总被引:2,自引:0,他引:2
Ronald?Maldonado-RodriguezEmail author Stancho?Pavlov Alberto?Gonzalez Abdallah?Oukarroum Reto?J.?Strasser 《Environmental Chemistry Letters》2003,1(3):201-205
In this paper we show that chlorophyll a fluorescence signals analysed with the self-organizing map (SOM) can be used as a routine tool for the monitoring and classification of pea varieties (Pisum sativum) according to their degree of resistance against drought stress. Fluorescence kinetics measurements were obtained from non-stressed plants. The aim of this study is to evaluate the applicability of artificial intelligence techniques in eco-physiological research. Our goal is to provide a fast tool that will contribute to the knowledge needed to develop strategies that would help to decrease the impact of environmental stress in agriculture and forestry. 相似文献
195.
Using the hedonic pricing approach, this paper investigates how the information released on public registries of contaminated and potentially contaminated sites affects nearby commercial and industrial properties in Baltimore, Maryland. The study found that industrial properties are virtually unaffected by proximity to a site with a history of contamination, while commercial properties do suffer an external cost due to the proximity to a contaminated site. This external cost is not cleared once the site has been cleaned up or has been pronounced to be harmless. It also found that the impacts of urban economic development policies, such as Empowerment Zones and Enterprise Zones, have had positive effects on industrial property values, but less so on commercial properties. In sum, brownfield properties in Baltimore are not particularly attractive investments for developers, and there is little potential for self-sustaining clean-up based on appropriate fiscal incentives, such as Tax Increment Financing. It is doubtful that ‘one size fits all’ measures to encourage the clean-up of contaminated sites can be successful in this context. 相似文献
196.
Gerd Sparovek Alberto Barretto Goran Berndes Sergio Martins Rodrigo Maule 《Mitigation and Adaptation Strategies for Global Change》2009,14(3):285-298
Governments are promoting biofuels and the resulting changes in land use and crop reallocation to biofuels production have
raised concerns about impacts on environment and food security. The promotion of biofuels has also been questioned based on
suggested marginal contribution to greenhouse gas emissions reduction, partly due to induced land use change causing greenhouse
gas emissions. This study reports how the expansion of sugarcane in Brazil during 1996–2006 affected indicators for environment,
land use and economy. The results indicate that sugarcane expansion did not in general contribute to direct deforestation
in the traditional agricultural region where most of the expansion took place. The amount of forests on farmland in this area
is below the minimum stated in law and the situation did not change over the studied period. Sugarcane expansion resulted
in a significant reduction of pastures and cattle heads and higher economic growth than in neighboring areas. It could not
be established to what extent the discontinuation of cattle production induced expansion of pastures in other areas, possibly
leading to indirect deforestation. However, the results indicate that a possible migration of the cattle production reached
further than the neighboring of expansion regions. Occurring at much smaller rates, expansion of sugarcane in regions such
as the Amazon and the Northeast region was related to direct deforestation and competition with food crops, and appear not
to have induced economic growth. These regions are not expected to experience substantial increases of sugarcane in the near
future, but mitigating measures are warranted. 相似文献
197.
Patricia Fitzpatrick Alberto FonsecaMary Louise McAllister 《Journal of Cleaner Production》2011,19(4):376-384
Much debate has taken place within the mineral policy community about whether or not meaningful progress has been made towards more sustainable practices. This paper investigates the changing approaches towards sustainable development undertaken by the Mining Association of Canada (MAC) over a period of approximately 20 years. The analysis begins in the early 1990s when MAC initiated the Whitehorse Mining Initiative (WMI) and concludes in 2010 when the association was operating under a strategy entitled Towards Sustainable Mining (TSM). The goal is to consider the nature of the learning that has taken place towards sustainability within the mineral industry using the case of a leading national mining association. The investigation was undertaken through a literature review as well as key informant interviews with stakeholders affected by the Canadian Mining Industry. Findings suggest that MAC’s approach to sustainable development has shifted from an ambitious and holistic partnership involving a range of stakeholders to a focused, member-specific agenda that addresses a few performance issues. The transition to TSM was based on lessons learned through working with the WMI and subsequent efforts. It reflects broader corporate tendencies to address social and ecological issues through corporate social responsibility initiatives. The implications of these trends suggest that voluntary initiatives in and of themselves should not be expected to replace the comprehensive regulatory responsibilities historically provided by government. 相似文献
198.
199.
Daria Sanna Alberto Addis Francesca Biagi Costantino Motzo Marcella Carcupino Paolo Francalacci 《Marine Biology》2008,153(3):269-275
Mitochondrial DNA (mtDNA) has been used extensively in animals for phylogenetic and population studies but it has been applied
only occasionally to mating systems analysis, where nuclear markers are usually preferred. We used denaturing-high performance
liquid chromatography (D-HPLC) to detect mitochondrial DNA polymorphisms to assess the genetic mating system in Syngnathus abaster. Our study of ten pregnant males, revealed polygyny in 30% of the males, who carried embryos originating from multiple females.
In addition, 30% of the pregnant males carried embryos with the same mitochondrial haplotype. This is not sufficient to demonstrate
polyandry but allows a rapid selection and a reduced sample size for further studies. In conclusion, the proposed technique
is time- and cost-effective, allows the certain identification of polygyny and provides useful information to study polyandry. 相似文献
200.
Vera S. Domingues Markos Alexandrou Vitor C. Almada D. Ross Robertson Alberto Brito Ricardo S. Santos Giacomo Bernardi 《Marine Biology》2008,154(3):465-474
The northeastern Atlantic and the Mediterranean Sea share geological histories and display great faunal affinities. The majority
of the Mediterranean species have Atlantic origins, with a few species with tropical affinities. These include the parrotfish
Sparisoma cretense and the wrasse Thalassoma pavo that are restricted to the subtropical northeastern Atlantic, the Macaronesian archipelagos (Azores, Madeira, and Canaries)
and the southern Mediterranean. The Pleistocene glaciations have been described as having different effects on the fauna of
the two regions. During glacial peaks, Mediterranean waters remained warmer than those of the adjacent Atlantic. Within the
eastern Atlantic, the effects of Pleistocene glaciations were differentiated. Here, we perform a comparative analysis focusing
on T. pavo and S. cretense populations from the northeastern Atlantic and the Mediterranean to assess the effects of Pleistocene glaciations in these
two species. Sequences from the mitochondrial control region were obtained and analyzed combining phylogeographic and demographic
approaches. Gene flow between Atlantic and Mediterranean populations was shown to be very high. The Mediterranean populations
of T. pavo and S. cretense showed high levels of genetic diversity, even in the eastern basin, pointing to an ancient colonization event. This suggests
that both species must have been able to persist in the Mediterranean during the cold Pleistocene periods. Historical migration
estimates revealed a Mediterranean towards Atlantic trend in the case of T. pavo, which may reflect the re-colonization of areas in the Atlantic by fish that survived the cold phases in relatively warmer
Mediterranean refugia. Our data also showed that within the Macaronesian Archipelagos, migrations occurred from Madeira towards
the Azores, for both T. pavo and S. cretense, thus supporting a post-glacial colonization of the Azores by fish that persisted in the warmer region of Madeira. Similar
geographic distributions, thermal affinities, and means of dispersion for T. pavo and S. cretense resulted in a similar response to the effects of Pleistocene glaciations, as evidenced by identical phylogeographic patterns. 相似文献