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211.
This, our second reply to Östensson, supplements our earlier more technical analysis with a simple intuitive explanation of how investor demand can be driving commodity prices higher even when investor stocks are falling. 相似文献
212.
Bourcier L Masson O Laj P Pichon JM Paulat P Freney E Sellegri K 《Journal of environmental radioactivity》2011,102(3):294-301
The atmospheric concentrations of 137Cs, 210Pb, and 7Be were measured over a three-year period at two research stations located less than 12 km apart and at different altitudes (puy de Dôme, 1465 m a.s.l. and Opme, 660 m a.s.l., France). Seasonal trends in all radionuclides were observed at both stations, with high concentration measured during the summer and low concentrations during the winter. The 210Pb concentrations at both stations were similar to each other. Higher concentrations of both 7Be and 137Cs were measured at puy de Dôme than at Opme. These observations can be explained by the stratospheric and upper tropospheric sources of 7Be and the long-range transportation of 137Cs at high altitudes. Air mass origins during sampling periods were classified into several groups by their route to the stations (marine, marine modified, continental and mediterranean). We observed that 7Be concentrations were constant regardless of the air mass origins, unlike 137Cs and 210Pb concentrations that increased when influenced by continental air masses. Higher 7Be concentrations were observed when air masses were arriving from the upper troposphere than from the boundary layer, the opposite was observed for 137Cs. The temporal trend in concentrations of 7Be shows good agreement with previous modelling studies suggesting that there is a good understanding of its sources and the atmospheric vertical mixing of this radionuclide. The sources and mixing of 210Pb, however, seem to be more complex than it appeared to be in previous modelling studies. 相似文献
213.
A new strategy of heavy crude oil removal from contaminated soils was studied. The hexane-acetone solvent mixture was used to investigate the ability of solvent extraction technique for cleaning up soils under various extraction conditions. The mixtures of hexane and acetone (25 vol%) were demonstrated to be the most effective in removing petroleum hydrocarbons from contaminated soils and approx 90% of saturates, naphthene aromatics, polar aromatics, and 60% of nC7-asphaltenes were removed. Kinetic experiments demonstrated that the equilibrium was reached in 5 min and the majority of the oil pollutants were removed within 0.5 min. The effect of the ratio between solvent and soil on the extraction efficiency was also studied and results showed that the efficiency would increase following the higher solvent soil ratio. Then the multistage continuous extraction was considered to enhance the removal efficiency of oil pollutants. Three stages crosscurrent and countercurrent solvent extraction with the solvent soil ratio 6:1 removed 97% oil contaminants from soil. Clearly the results showed that the mixed-solvent of hexane and acetone (25 vol%) with character of low-toxic, acceptable cost and high efficiency was promising in solvent extraction to remove heavy oil fractions as well as petroleum hydrocarbons from contaminated soils. 相似文献
214.
Hanzel J Thullner M Harms H Wick LY 《Environmental pollution (Barking, Essex : 1987)》2011,159(4):858-864
Limited information exists on influences of the diffusive transport of volatile organic contaminants (VOC) on bacterial activity in the unsaturated zone of the terrestrial subsurface. Diffusion of VOC in the vapor-phase is much more efficient than in water and results in effective VOC transport and high bioavailability despite restricted mobility of bacteria in the vadose zone. Since many bacteria tend to accumulate at solid-water, solid-air and air-water interfaces, such phase boundaries are of a special interest for VOC-biodegradation. In an attempt to evaluate microbial activity toward air-borne substrates, this study investigated the spatio-temporal interplay between growth of Pseudomonas putida (NAH7) on vapor-phase naphthalene (NAPH) and its repercussion on vapor-phase NAPH concentrations. Our data demonstrate that growth rates of strain PpG7 were inversely correlated to the distance from the source of vapor-phase NAPH. Despite the high gas phase diffusivity of NAPH, microbial growth was absent at distances above 5 cm from the source when sufficient biomass was located in between. This indicates a high efficiency of suspended bacteria to acquire vapor-phase compounds and influence headspace concentration gradients at the centimeter-scale. It further suggests a crucial role of microorganisms as biofilters for gas-phase VOC emanating from contaminated groundwater or soil. 相似文献
215.
Helmut W. Fischer Susanne Ulbrich Daniela Pittauerov Bernd Hettwig 《Journal of environmental radioactivity》2009,100(12):1079-1085
Motivated by the detection of 131I in river sediment in routine long-term surveillance samples, a systematic short-term study of the wastewater treatment chain was planned and conducted. Inflow, effluent and primary sludge were collected on a daily basis during two weeks at a regional wastewater treatment plant. Samples were investigated by gamma spectroscopy. Four medically used isotopes could be identified (131I and 99mTc regularly, 153Sm and 123I sporadically). The concentration levels coincide well with literature data for 131I, and with our own long-term data for 131I and 99mTc for the same plant. Cosmogenic 7Be activity in primary sludge correlated well with rainfall intensity. Surface sediment was sampled at low tide at both shores of the river, up- and downstream of the plant. 131I was identified in all samples, with a sharp maximum (about 100 Bq kg−1 d.m.) at the discharge point of the plant and lower levels elsewhere, decreasing monotonically in downstream direction. 7Be and 137Cs showed the same behaviour, but no peak at the discharge point. Predictions from simple equilibrium models for the transport and sedimentation of 131I show good agreement with the experimental data and suggest that the wastewater treatment plant is the main source for this isotope. 相似文献
216.
Sylwia Wojas Sonia Plaza Oskar Siemianowski Anna Ruszczyńska Danuta M. Antosiewicz 《Environmental pollution (Barking, Essex : 1987)》2009,157(10):2781-2789
Arabidopsis MRPs/ABCCs have been shown to remove various organic and inorganic substrates from the cytosol to other subcellular compartments. Here we first demonstrate that heterologous expression of AtMRP7 in tobacco (Nicotiana tabacum var. Xanthi) modifies cadmium accumulation, distribution and tolerance. Arabidopsis MRP7 was localized both in the tonoplast and in the plasma membrane when expressed in tobacco. Its overexpression increased tobacco Cd-tolerance and resulted in enhanced cadmium concentration in leaf vacuoles, indicating more efficient detoxification by means of vacuolar storage. Heterologous AtMRP7 expression also led to more efficient retention of Cd in roots, suggesting a contribution to the control of cadmium root-to-shoot translocation. The results underscore the use of AtMRP7 in plant genetic engineering to modify the heavy-metal accumulation pattern for a broad range of applications. 相似文献
217.
218.
L andsat-7 SLC- OFF ETM遥感数据下载及在太湖蓝藻水华监测中的应用 总被引:5,自引:1,他引:4
李旭文 《环境监测管理与技术》2009,21(3):54-57
利用互联网上USGS提供的公益性Landsat-7SLC—OFFETM遥感数据下载服务,建立了太湖地区2003年-2008年ETM遥感影像数据库,开展蓝藻水华面积解译和暴发特征分析。统计结果表明,2007年和2008年太湖蓝藻水华暴发呈加剧态势。 相似文献
219.
Choi JW Lee W Lee DB Park CH Kim JS Jang YH Kim Y 《Environmental monitoring and assessment》2007,129(1-3):37-42
The immobilized cell using self-assembled synthetic oligopeptide was applied to the electrochemical detection of pathogen
infection. Thin films based on cysteine-terminated synthetic oligopeptides were fabricated for the immobilization of HeLa
cell on gold (Au) substrate. Layer formation and immobilization of the cell were investigated with surface plasmon resonance
(SPR) and electrochemical impedance spectroscopy (EIS). Experimental results showed that the thin film of cysteine-terminated
synthetic oligopeptide was successfully fabricated and it could be applied for the immobilization of HeLa cells. The adhered
living cell was exposed to E. coli O157:H7, which induced the change of SPR angle and electrochemical impedance signal. The proposed cell immobilization method
using self-assembly technique can be applied to construct the cell microarray for on-site pathogen monitoring. 相似文献
220.
Alexandra L. DeCandia Andrew P. Dobson Bridgett M. vonHoldt 《Conservation biology》2018,32(4):798-807
Pathogens pose serious threats to human health, agricultural investment, and biodiversity conservation through the emergence of zoonoses, spillover to domestic livestock, and epizootic outbreaks. As such, wildlife managers are often tasked with mitigating the negative effects of disease. Yet, parasites form a major component of biodiversity that often persist. This is due to logistical challenges of implementing management strategies and to insufficient understanding of host–parasite dynamics. We advocate for an inclusive understanding of molecular diversity in driving parasite infection and variable host disease states in wildlife systems. More specifically, we examine the roles of genetic, epigenetic, and commensal microbial variation in disease pathogenesis. These include mechanisms underlying parasite virulence and host resistance and tolerance, and the development, regulation, and parasite subversion of immune pathways, among other processes. Case studies of devil facial tumor disease in Tasmanian devils (Sarcophilus harrisii) and chytridiomycosis in globally distributed amphibians exemplify the broad range of questions that can be addressed by examining different facets of molecular diversity. For particularly complex systems, integrative molecular analyses present a promising frontier that can provide critical insights necessary to elucidate disease dynamics operating across scales. These insights enable more accurate risk assessment, reconstruction of transmission pathways, discernment of optimal intervention strategies, and development of more effective and ecologically sound treatments that minimize damage to the host population and environment. Such measures are crucial when mitigating threats posed by wildlife disease to humans, domestic animals, and species of conservation concern. 相似文献