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61.
Daniele Torriani Pierluigi Calanca Markus Lips Helmut Ammann Martin Beniston Jürg Fuhrer 《Regional Environmental Change》2007,7(4):209-221
A simple model of yield was used along with climate scenarios to assess the impact of climate change on grain maize productivity
and associated economic risk in Switzerland. In a first application, changes in the precipitation regime alone were shown
to affect the distribution of yield considerably, with shifts not only in the mean but also in the standard deviation and
the skewness. Production risk was found to respond more markedly to changes in the long-term mean than in the inter-annual
variability of seasonal precipitation amounts. In a further application, yield projections were generated with respect to
a full climate scenario, with the emission pathway as specified in the IPCC A2 scenario. Anticipation of the sowing date was
found to reduce the negative impact of climate change on yield stability, but was not sufficient to ensure average productivity
levels comparable to those observed at present. We argued that this was caused by the reduction in the duration of the growing
season, which had a stronger impact than suggested by previous studies. Assuming no change in price relations, the results
also revealed a strong increase in production risk with climate change, with more than a doubling in the probability of yield
falling short of a critical threshold as compared to today’s situation. 相似文献
62.
Specchiulli Antonietta Scirocco Tommaso D’Adamo Raffaele Cilenti Lucrezia Fabbrocini Adele Cassin Daniele Penna Pierluigi Renzi Monia Bastianoni Simone 《Journal of Coastal Conservation》2016,20(5):363-374
Phytoplankton and benthic vegetation biomass undergoes spatial-temporal changes in relation to their life cycle, but also to meteorological conditions, physical-chemical variables, organic input and internal dynamism. The main aim of this work was to observe the effect of all environmental variables on the vegetative dynamic process in a protected zone of a Mediterranean costal lagoon (Lesina lagoon, SE Italy). Seven samplings were performed from 2010 to 2012 at 30 sites for nutrient and chlorophyll analyses, while TOC measurements and wet biomass evaluation were performed at 10 sites. Temperature, salinity and oxygen saturation were also measured by multiparametric probe and a visual census for vegetation was performed. Sites close to freshwater inflow were characterized by lower temperature and salinity, and high nitrate, with maxima of 191.05 μM in May 2010 and more than 250 μM in October 2010. Silicates drastically decreased from May 2010 (87.57 μM) to July 2010 (6.15 μM) and increased again in October (74.99 μM). Chl a concentrations were not on average higher than 6 mg m?3, but peaks of 20 mg m?3 were observed during May 2011 and May 2012. Benthic vegetation wet biomass collected in 2010 was approximately twice that collected in 2012, with a maximum of 27,554 g m?2 and a dominance of macroalgae (70 % in May 2010 and 40 % in August 2010). During period 2010, a simultaneous and drastic decreasing of both mean values of wet biomass and chl a was observed from May to October 2010. During period 2012 a shift of vegetation biomass was shown from May (phytoplankton prevalence) to August 2012, with angiosperm prevalence (more than 30 %). 相似文献
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64.
Adami G Cabras I Predonzani S Barbieri P Reisenhofer E 《Environmental monitoring and assessment》2007,125(1-3):291-299
Chromium, nickel, copper, zinc and cadmium were determined in sediments of the Niger Delta (Nigeria) in order to discriminate
between natural metal sources and anthropogenic ones. Surface sediments were collected at seven sites along a new gas pipeline
near Port Harcourt, between the New Calabar River and the Bonny River towards Bonny town. Chemical characterisation is obtained
by hydrofluoric–nitric acid digestion procedure, providing the ‘total’ (‘residual’) metal contents. Information about the
anthropogenic metal fraction was obtained by cold diluted hydrochloric acid extraction procedure. This ‘labile’ acid soluble
fraction of metals, perhaps due to relatively recent inputs in the sediments, constitutes the fraction more likely to be available
to marine organisms, and furnishes a first evaluation of the possible toxicity of sediments of this sensitive ecosystem. Zinc
appears to be the most available of all the heavy metals: its ‘labile’ fraction attains 40–50% of the ‘total’ zinc in sediment.
Sites near Port Harcourt city are the most contaminated. All the examined metals are one order of magnitude below the respective
values proposed as a limit for toxicity and are comparable with those observed by other authors in similar Niger Delta areas.
Some anomalous data found near Port Harcourt city suggest that zinc and cadmium are the metals that require further monitoring.
Their anthropogenic source could be derived from urban and industrial sewage. 相似文献