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811.
812.
813.
Hydrocarbon vapors associated with spilled petroleum products arouse regulatory concern and can pose a significant health and safety risk. While petroleum products do not contain a significant amount of methane (CH 4 ), high CH 4 contents in soil gas near petroleum spills have been reported. While CH 4 is nontoxic, its accumulation in shallow soil gas represents a potential explosion and asphyxiation hazard, especially in confined spaces. Identifying the source and origin of shallow CH 4 accumulations is an important part of evaluating potential exposure pathways, selecting appropriate remedial measures, and determining environmental liability. This paper discusses the potential nature and anthropogenic sources for shallow CH 4 and how integration of geological, geochemical, and land use data can be used to determine its origin and identify its source. Two case studies are presented, one where CH 4 associated with a gasoline spill is shown to be derived from a natural source rather than the gasoline, and a second where CH 4 associated with spilled crude oil is shown to be produced in the vadose zone by biodegradation of the oil. 相似文献
814.
Planetary Stewardship in an Urbanizing World: Beyond City Limits 总被引:1,自引:0,他引:1
Sybil P. Seitzinger Uno Svedin Carole L. Crumley Will Steffen Saiful Arif Abdullah Christine Alfsen Wendy J. Broadgate Frank Biermann Ninad R. Bondre John A. Dearing Lisa Deutsch Shobhakar Dhakal Thomas Elmqvist Neda Farahbakhshazad Owen Gaffney Helmut Haberl Sandra Lavorel Cheikh Mbow Anthony J. McMichael Joao M. F. deMorais Per Olsson Patricia Fernanda Pinho Karen C. Seto Paul Sinclair Mark Stafford Smith Lorraine Sugar 《Ambio》2012,41(8):787-794
Cities are rapidly increasing in importance as a major factor shaping the Earth system, and therefore, must take corresponding responsibility. With currently over half the world’s population, cities are supported by resources originating from primarily rural regions often located around the world far distant from the urban loci of use. The sustainability of a city can no longer be considered in isolation from the sustainability of human and natural resources it uses from proximal or distant regions, or the combined resource use and impacts of cities globally. The world’s multiple and complex environmental and social challenges require interconnected solutions and coordinated governance approaches to planetary stewardship. We suggest that a key component of planetary stewardship is a global system of cities that develop sustainable processes and policies in concert with its non-urban areas. The potential for cities to cooperate as a system and with rural connectivity could increase their capacity to effect change and foster stewardship at the planetary scale and also increase their resource security. 相似文献
815.
Concentrations of PCDD/Fs, PCBs and PBDEs were measured in 56 egg samples collected from waterbirds of different species (Great Egret, Little Egret, Night Heron and Chinese Pond Heron) from different regions of Hong Kong (Ho Sheung Heung, Mai Po Village and Mai Po Lung Village) during 2000 and 2006. Dominance of 2,3,4,7,8-PeCDF indicates a signature associated with commercial usage of PCBs. Although no significant variations were observed within- and between-site in the levels of PCDD/Fs, coplanar PCBs and PBDEs, the concentrations of coplanar PCBs were much higher than PCDD/Fs. Similarity in composition profiles of PCDD/F and coplanar PCBs from different egretries is possibly associated with non-point sources of these contaminants to Hong Kong. Predominant accumulation of BDE-47, BDE-99 and BDE-100 suggested the penta-BDE technical mixtures usage in Hong Kong and its vicinity. Toxic equivalency and Monte Carlo simulation technique showed potential risks on waterbirds due to their exposure to PCDD/Fs. 相似文献
816.
Duarte CM Agustí S Wassmann P Arrieta JM Alcaraz M Coello A Marbà N Hendriks IE Holding J García-Zarandona I Kritzberg E Vaqué D 《Ambio》2012,41(1):44-55
The Arctic marine ecosystem contains multiple elements that present alternative states. The most obvious of which is an Arctic Ocean largely covered by an ice sheet in summer versus one largely devoid of such cover. Ecosystems under pressure typically shift between such alternative states in an abrupt, rather than smooth manner, with the level of forcing required for shifting this status termed threshold or tipping point. Loss of Arctic ice due to anthropogenic climate change is accelerating, with the extent of Arctic sea ice displaying increased variance at present, a leading indicator of the proximity of a possible tipping point. Reduced ice extent is expected, in turn, to trigger a number of additional tipping elements, physical, chemical, and biological, in motion, with potentially large impacts on the Arctic marine ecosystem. 相似文献
817.
Idris SM Jones PL Salzman SA Croatto G Allinson G 《Environmental science and pollution research international》2012,19(4):1159-1170
Introduction
Two emergent macrophytes, Arundo donax and Phragmites australis, were established in experimental subsurface flow, gravel-based constructed wetlands (CWs) receiving untreated recirculating aquaculture system wastewater.Materials and methods
The hydraulic loading rate was 3.75 cm day?1. Many of the monitored water quality parameters (biological oxygen demand [BOD], total suspended solids [TSS], total phosphorus [TP], total nitrogen [TN], total ammoniacal nitrogen [TAN], nitrate nitrogen [NO3], and Escherichia coli) were removed efficiently by the CWs, to the extent that the CW effluent was suitable for use on human food crops grown for raw produce consumption under Victorian state regulations and also suitable for reuse within aquaculture systems.Results and discussion
The BOD, TSS, TP, TN, TAN, and E. coli removal in the A. donax and P. australis beds was 94%, 67%, 96%, 97%, 99.6%, and effectively 100% and 95%, 87%, 95%, 98%, 99.7%, and effectively 100%, respectively, with no significant difference (p?>?0.007) in performance between the A. donax and P. australis CWs. In this study, as expected, the aboveground yield of A. donax top growth (stems + leaves) (15.0?±?3.4 kg wet weight) was considerably more than the P. australis beds (7.4?±?2.8 kg wet weight). The standing crop produced in this short (14-week) trial equates to an estimated 125 and 77 t ?ha?1 year?1 biomass (dry weight) for A. donax and P. australis, respectively (assuming that plant growth is similar across a 250-day (September–April) growing season and a single-cut, annual harvest).Conclusion
The similarity of the performance of the A. donax- and P. australis-planted beds indicates that either may be used in horizontal subsurface flow wetlands treating aquaculture wastewater, although the planting of A. donax provides additional opportunities for secondary income streams through utilization of the energy-rich biomass produced.818.
Paul B. Thompson Kyle Powys Whyte 《Journal of Agricultural and Environmental Ethics》2012,25(4):485-498
What is the significance of the wicked problems framework for environmental philosophy? In response to wicked problems, environmental scientists are starting to welcome the participation of social scientists, humanists, and the creative arts. We argue that the need for interdisciplinary approaches to wicked problems opens up a number of tasks that environmental philosophers have every right to undertake. The first task is for philosophers to explore new and promising ways of initiating philosophical research through conducting collaborative learning processes on environmental issues. The second task is for philosophers to recognize the value of philosophical skills in their engagements with members of other disciplines and walks of life in addressing wicked problems. The wicked problems framework should be seen as an important guide for facilitating philosophical research that is of relevance to problems like climate change and sustainable agriculture. 相似文献
819.
Dybowska AD Croteau MN Misra SK Berhanu D Luoma SN Christian P O'Brien P Valsami-Jones E 《Environmental pollution (Barking, Essex : 1987)》2011,159(1):266-273
Understanding the behavior of engineered nanoparticles in the environment and within organisms is perhaps the biggest obstacle to the safe development of nanotechnologies. Reliable tracing is a particular issue for nanoparticles such as ZnO, because Zn is an essential element and a common pollutant thus present at elevated background concentrations. We synthesized isotopically enriched (89.6%) with a rare isotope of Zn (67Zn) ZnO nanoparticles and measured the uptake of 67Zn by L. stagnalis exposed to diatoms amended with the particles. Stable isotope technique is sufficiently sensitive to determine the uptake of Zn at an exposure equivalent to lower concentration range (<15 μg g−1). Without a tracer, detection of newly accumulated Zn is significant at Zn exposure concentration only above 5000 μg g−1 which represents some of the most contaminated Zn conditions. Only by using a tracer we can study Zn uptake at a range of environmentally realistic exposure conditions. 相似文献
820.
Naile JE Khim JS Wang T Wan Y Luo W Hu W Jiao W Park J Ryu J Hong S Jones PD Lu Y Giesy JP 《Environmental pollution (Barking, Essex : 1987)》2011,159(4):907-917
Polychlorinated-dibenzo-p-dioxins and -dibenzofurans (PCDD/Fs) were measured in soils and sediments from the Yellow Sea region. Korean soils and sediments mostly contained detectable PCDD/Fs and showed a widespread distribution among locations. Soil and sedimentary PCDD/Fs from China were comparable to or less than those in Korea. The patterns of relative concentrations of individual congeners in soils were different between the two countries, but similar in sediments. Sources of PCDD/Fs in China and Korea were found to be independent of each other and their distributions reflected matrix-dependent accumulation. Spatial distribution indicated some point sources in Korea while Chinese sources were more widespread and diffuse. PCDD/Fs measured in the coastal areas of the Yellow Sea were comparable to or less than those previously reported in for eastern Asia. However, ∑TEQs in soils and sediments were near to or, in some cases exceeded environmental quality guidelines. 相似文献