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991.
This paper analyzes the United Nations Organization's Kyoto Protocol nations to address two questions. First, what are the environmental production efficiency rankings of these nations? Second, is there a relationship between a nation's ratification status and its environmental production efficiency ranking? Our findings suggest that the nations that have ratified the Kyoto Protocol are more likely to be environmentally production efficient as compared to the nations that have not ratified the Protocol. 相似文献
992.
993.
This study was carried out between January and March 1995 on the intertidal sand flats of Tang Khen Bay, Phuket, South Thailand,
where the soldier crab Dotilla myctiroides (H. Milne-Edwards) occurs in densities of up to 120 m−2. In this bay, long, ribbon-like sand waves (wavelength 40 m, height 0.4 m) are interspersed with shallow pools, running approximately
parallel to the shore. During daylight low-tides, exposure of the sand waves is followed 15 to 20 min later by the emergence
of the crabs which have been buried under the sediment surface during high tide. Their subsequent burrowing and feeding activity
results in the production of large numbers of sand pellets on the sediment surface. Most crabs retreat down their burrows,
and some also plug the burrow entrance, prior to being covered by the incoming tide. The crab burrows have a distinct distribution
on the sand waves. Burrows are most dense at the top of each sand wave, and a band of unburrowed sediment adjoins the adjacent
tidal pools. Crabs are most abundant between mean high-water neap-tide level and mean low-water neap-tide level, where the
median particle size of the surface sediment is ∼2 . Measurements of water-table depth below the sand waves and the exposure
time of the sediment indicated that, where sediment size is suitable, the main factor controlling crab distribution is the
duration of daytime exposure. This observation is in contrast to those of many previous studies, which have suggested that
water-table height and sediment drainage are the main factors controlling the distribution of D. myctiroides.
Received: 14 January 1998 / Accepted: 6 May 1999 相似文献
994.
Bioremediation of tributyltin contaminated sediment: degradation enhancement and improvement of bioavailability to promote treatment processes 总被引:1,自引:0,他引:1
Bioremediation of tributyltin (TBT) contaminated sediment was studied and degradation enhancement and improvement of bioavailability were also investigated. In TBT spiked sediment, the half-life of TBT in the control sample, representing natural attenuation, was 578 d indicating its persistence. In the stimulated sample (pH 7.5, aeration and incubated at 28 °C), the half-life was significantly reduced to 11 d. Further stimulation by nutrient addition (succinate, glycerol and l-arginine) or inoculation with Enterobacter cloacae (∼107 viable cells g−1 of sediment) resulted in half-life reduction to 9 and 10 d, respectively. In non-spiked sediment, the indigenous microorganisms were able to degrade aged TBT, but the extended period of contamination decreased the degradation efficiency. To improve bioavailability, addition of surfactant, adjustment of salinity and sonication were studied. The highest percentage solubilisation of TBT in water was obtained by adjusting salinity to 20 psu, which increased the solubility of TBT from 13% to 33%. Half-lives after bioavailability was improved were 5, 4 and 4 d for stimulation, stimulation w/nutrient addition and stimulation w/inoculation, respectively. However, natural attenuation in the control sample was not enhanced. The results show that providing suitable conditions is important in enhancing TBT biodegradation, and bioavailability improvement additionally increased the rate and degraded amount of TBT. Unfortunately, nutrient addition and inoculation of the degrader did not enhance the degradation appreciably. 相似文献
995.
A. Hoese S. A. Clay D. E. Clay J. Oswald T. Trooien R. Thaler 《Journal of environmental science and health. Part. B》2013,48(4):371-378
This study assessed the runoff potential of tylosin and chlortetracycline (CTC) from soils treated with manure from swine fed rations containing the highest labeled rate of each chemical. Slurry manures from the swine contained either CTC at 108 μ g/g or tylosin at 0.3 μ g/g. These manures were surface applied to clay loam, silty clay loam, and silt loam soils at a rate of 0.22 Mg/ha. In one trial, tylosin was applied directly to the soil surface to examine runoff potential of water and chemical when manure was not present. Water was applied using a sprinkler infiltrometer 24-hr after manure application with runoff collected incrementally every 5 min for about 45 min. A biofilm crust formed on all manure-treated surfaces and infiltration was impeded with > 70% of the applied water collected as runoff. The total amount of CTC collected ranged from 0.9 to 3.5% of the amount applied whereas tylosin ranged from 8.4 to 12%. These data indicate that if surface-applied manure contains antimicrobials, runoff could lead to offsite contamination. 相似文献
996.
A value of statistical life (VSL) is used in cost-benefit analysis (CBA) as a monetary measure of the benefits to people from small risk reductions that arise from safety projects. Despite its widespread use in a number of countries, the concept of a VSL remains controversial, not least because it implies acceptance of the underlying ethical assumptions of CBA together with the idea that ‘social welfare’ can be measured and aggregated in some manner. In addition, to comply with theory, variable VSLs for different groups within society would be advocated. However, without fail, empirically, it is the case that those countries that employ a willingness to pay based approach to cost-benefit analysis of a safety project appraisal tend to use a single value for that accident context that is independent of the per capita income level, or indeed other personal characteristics, of the sub-group in society to which the safety improvement will actually apply. This article presents a straightforward, but theoretically justified adaptation to the calculation of a VSL which allows empirical practice by policymakers i.e. the application of a “common” VSL for any particular hazard within a given society, to be compatible with a CBA decision making approach. 相似文献
997.
Liew Juneng Mohd Talib Latif Fredolin T. Tangang Haslina Mansor 《Atmospheric environment (Oxford, England : 1994)》2009,43(30):4584-4594
The recurrence of forest fires in Southeast Asia and associated biomass burning, has contributed markedly to the problem of trans-boundary haze and the long-range movement of pollutants in the region. Air pollutants, specifically particulate matter in the atmosphere, have received extensive attention, mainly because of their adverse effect on people's health. In this study, the spatial and temporal variability of the PM10 concentration across Malaysia was analyzed by means of the rotated principal component analysis. The results suggest that the variability of the PM10 concentration can be decomposed into four dominant modes, each characterizing different spatial and temporal variations. The first mode characterizes the southwest coastal region of the Malaysian Peninsular with the PM10 showing a peak concentration during the summer monsoon i.e. when the winds are predominantly southerlies or southwesterlies, and a minimal concentration during the winter monsoon. The second mode features the region of western Borneo with the PM10 exhibiting a concentration surge in August–September, which is likely to be the result of the northward shift of the Inter Tropical Convergence Zone (ITCZ) and the subsequent rapid arrival of the rainy season. The third mode delineates the northern region of the Malaysian Peninsular with strong bimodality in the PM10 concentration. Seasonally, this component exhibits two concentration maxima during the late winter and summer monsoons, as well as two minima during the inter-monsoon periods. The fourth dominant mode characterizes the northern Borneo region which exhibits weaker seasonality of the PM10 concentration. Generally, the seasonal fluctuation of the PM10 concentration is largely associated with the seasonal variation of rainfall in the country. However, in addition to this, the PM10 concentration also fluctuates markedly in two timescale bands i.e. 10–20 days quasi-biweekly (QBW) and 30–60 days lower frequency (LF) band of the intra-seasonal timescales. These intra-seasonal fluctuations show strong seasonality with the largest fraction of variance occurring during the boreal summer and the weakest variance during the winter. Generally, the LF intra-seasonal oscillation is stronger compared to the QBW intra-seasonal band. 相似文献
998.
999.
The toxicity and bioaccumulation of two heavy metals—lead (Pb) and cadmium (Cd)—in a semi-aquatic plant, Colocasia esculenta (L. Schott), from a synthetic heavy metal solution were studied. Young plants of equal size were grown hydroponically in shallow raceways containing Hoagland medium amended with 20, 40, and 60 mg l?1 of Pb and 2, 4, and 6 mg l?1 of Cd. The medium containing heavy metals was allowed to flow through the raceways with a change in influent heavy metal solution on every 5th day. The experiment was continued for 20 days. A set of control raceways—one comprised of nutrient medium with heavy metal supplements, devoid of plants, and another with the plants and nutrient medium having no metal supplement—was also simultaneously run. Chlorosis in the leaves was the prominent toxicity symptom observed due to Pb and Cd on the test plants. A significant decrease in the relative growth, biomass productivity, and total chlorophyll content were noticed in the plants with an increase in concentration of metal supplement in the solution and exposure time. Both metals accumulated to higher concentrations in the roots than in shoots, suggesting that the metals were bound to the root cells and their translocation to the leaves was limited. The results of the 20-day-long experiments indicate that from a phytoremediation perspective, C. esculenta is a promising plant species for remediation of wastewater polluted with lower concentrations of Pb and Cd. 相似文献
1000.