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31.
George Zittis Panos Hadjinicolaou Mohammed Fnais Jos Lelieveld 《Regional Environmental Change》2016,16(7):1863-1876
According to observed twentieth century temperature trends and twenty-first century climate model projections, the region that encompasses the eastern Mediterranean and the Middle East (EMME) is identified as a climate change hot spot. We extend previous studies by a comprehensive climatology of heat waves in the EMME based on regional climate model simulations for the recent past and the end of the twenty-first century. A percentile-based definition of heat waves is used to account for local climatic conditions. Spatial patterns of several heat wave properties are assessed and associated with atmospheric circulation regimes over specific locations. To cover a range of possible future climates, we use three SRES emission scenarios. According to our results, all indices that characterize heat wave severity will strongly increase compared with the control period of 1961–1990. The northern part of the EMME could be exposed to increased heat wave amplitudes by 6–10 °C, and the southern part may experience 2–3 months more combined hot days and tropical nights. Heat wave peak temperatures will be higher due to the overall mean warming as well as stronger summer anticyclonic conditions. The projected changes will affect human health and the environment in multiple ways and call for impact studies to support the development of adaptation strategies. 相似文献
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George E. Halkos Epameinondas A. Paizanos 《Journal of Environmental Planning and Management》2017,60(1):135-157
This paper explores the relationship between government spending and environmental quality using panel data for 94 countries for the period 1970–2008. We identify and estimate three distinct channels that comprise the total direct effect of government expenditure on air pollution, namely a marginal effect, an effect conditional on economic growth and an effect conditional on institutional quality. Since adjustment rate of emissions to their equilibrium level is slow due to technological and institutional reasons, we explicitly take into account dynamics by applying appropriate econometric methods. The results demonstrate that there is a significant alleviating direct effect of government expenditure on SO2 and NOx emissions, which increases with the level of economic growth and democracy. However, there is no evidence of a significant effect on pollutants with more global impact on the environment and human health, like N2O and CO2, implying that the adoption of international environmental treaties is required in this case. 相似文献
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John E. Hobbie Gaius R. Shaver Edward B. Rastetter Jessica E. Cherry Scott J. Goetz Kevin C. Guay William A. Gould George W. Kling 《Ambio》2017,46(1):160-173
Long-term measurements of ecological effects of warming are often not statistically significant because of annual variability or signal noise. These are reduced in indicators that filter or reduce the noise around the signal and allow effects of climate warming to emerge. In this way, certain indicators act as medium pass filters integrating the signal over years-to-decades. In the Alaskan Arctic, the 25-year record of warming of air temperature revealed no significant trend, yet environmental and ecological changes prove that warming is affecting the ecosystem. The useful indicators are deep permafrost temperatures, vegetation and shrub biomass, satellite measures of canopy reflectance (NDVI), and chemical measures of soil weathering. In contrast, the 18-year record in the Greenland Arctic revealed an extremely high summer air-warming of 1.3 °C/decade; the cover of some plant species increased while the cover of others decreased. Useful indicators of change are NDVI and the active layer thickness. 相似文献
36.
K.R. Renjith V. Sudheesh Anu Shaji Ejin George Manju Mary Joseph C.S. Ratheesh Kumar 《毒物与环境化学》2016,98(1):36-52
The spatial and temporal variations of some trace metals in the surface sediments of Cochin Estuary were analyzed along with their geochemical associations to identify the possible sources, bioavailability and the health risks posed by them. The dominance of kaolinite and suggested that clay minerals distribution is influenced by sediment sorting. Total metal analysis revealed enrichment for Cd, Pb and Zn due to anthropogenic activities. The speciation analysis established that notwithstanding the large availability, carbonate as well as organic and sulfides bound fractions showed negligible associations with most of the metals. Hydrous Fe–Mn oxides appeared to play a major role in controlling the fate and transport of these metals in the sediments of Cochin Estuary. Lower contribution of the residual fractions for Cd (21%–26%), Pb (<60%) and Zn (24%–42%) indicated an obvious increase of other geochemical fractions. Risk assessment analysis revealed that regardless of total concentration, none of the analyzed metals were at safe levels in the estuary as appreciable percentages were found to be associated with mobile geochemical forms. The speciation study conspicuously established that the metals originating from non-geogenic sources are largely associated with the labile fractions and hence are more detrimental to the aquatic biota. 相似文献
37.
Elizabeth Guthrie Nichols Rachel L. Cook James E. Landmeyer Brad Atkinson Donald R. Malone George Shaw Leilani Woods 《补救:环境净化治理成本、技术与工艺杂志》2014,24(2):29-46
A former bulk fuel terminal in North Carolina is a groundwater phytoremediation demonstration site where 3,250 hybrid poplars, willows, and pine trees were planted from 2006 to 2008 over approximately 579,000 L of residual gasoline, diesel, and jet fuel. Since 2011, the groundwater altitude is lower in the area with trees than outside the planted area. Soil‐gas analyses showed a 95 percent mass loss for total petroleum hydrocarbons (TPH) and a 99 percent mass loss for benzene, toluene, ethylbenzene, and xylenes (BTEX). BTEX and methyl tert‐butyl ether concentrations have decreased in groundwater. Interpolations of free‐phase, fuel product gauging data show reduced thicknesses across the site and pooling of fuel product where poplar biomass is greatest. Isolated clusters of tree mortalities have persisted in areas with high TPH and BTEX mass. Toxicity assays showed impaired water use for willows and poplars exposed to the site's fuel product, but Populus survival was higher than the willows or pines on‐site, even in a noncontaminated control area. All four Populus clones survived well at the site. © 2014 Wiley Periodicals, Inc.* 相似文献
38.
Nikolaos Nikolioudakis George Koumoundouros Sotiris Kiparissis Stylianos Somarakis 《Marine Biology》2010,157(5):991-1001
The present study attempts to highlight the value of multi-character approaches for defining thresholds in fish ontogeny,
like the onset of the juvenile period. We developed techniques to objectively define the transition from larval to juvenile
development using morphometric as well as morphological characters and exemplify the multi-character approach on newly settled
white sea-breams (Diplodus sargus sargus) collected from the eastern Mediterranean. The morphometric analysis was based on principles of multivariate allometry whereas
the analysis of morphology, on assigning a suite of selected characters (here related to external morphology and osteological
development) into larval, transforming and juvenile states. The size-at-change in multivariate allometric growth (L
m) is considered here to denote mean length-at-metamorphosis. An almost perfect match is demonstrated between L
m (‘multivariate morphometry’) and mean size-at-morphological change (‘multivariate morphology’) in white sea-bream. 相似文献
39.
Optimum conditions for microbial carbonate precipitation 总被引:3,自引:0,他引:3
The type of bacteria, bacterial cell concentration, initial urea concentration, reaction temperature, the initial Ca(2+) concentration, ionic strength, and the pH of the media are some factors that control the activity of the urease enzyme, and may have a significant impact on microbial carbonate precipitation (MCP). Factorial experiments were designed based on these factors to determine the optimum conditions that take into consideration economic advantage while at the same time giving quality results. Sporosarcina pasteurii strain ATCC 11859 was used at constant temperature (25°C) and ionic strength with varying amounts of urea, Ca(2+), and bacterial cell concentration. The results indicate that the rate of ureolysis (k(urea)) increases with bacterial cell concentration, and the bacterial cell concentration had a greater influence on k(urea) than initial urea concentration. At 25 mM Ca(2+) concentration, increasing bacterial cell concentration from 10(6) to 10(8)cells mL?1 increased the CaCO(3) precipitated and CO(2) sequestrated by over 30%. However, when the Ca(2+) concentration was increased 10-fold to 250 mM Ca(2+), the amount of CaCO(3) precipitated and CO(2) sequestrated increased by over 100% irrespective of initial urea concentration. Consequently, the optimum conditions for MCP under our experimental conditions were 666 mM urea and 250 mM Ca(2+) at 2.3×10? cells mL?1 bacterial cell concentration. However, a greater CaCO(3) deposition is achievable with higher concentrations of urea, Ca(2+), and bacterial cells so long as the respective quantities are within their economic advantage. X-ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-ray analyzes confirmed that the precipitate formed was CaCO(3) and composed of predominantly calcite crystals with little vaterite crystals. 相似文献
40.