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81.
Holocene fire history from the Greater Blue Mountains World Heritage Area, New South Wales, Australia: the climate, humans and fire nexus 总被引:2,自引:1,他引:1
This study presents a reconstruction of the fire activity of the last ~14,200 cal. years BP (before AD 1950) from Gooches Crater Right, located on the Newnes Plateau, approximately 150 km to the west of Sydney (~33°27′S, 150°16′E)
within the Blue Mountains National Park. Charcoal analysis and palynology were undertaken with the aim of untangling any inter-relationship
between climate, humans and fire. A chronology of the site was provided by radiocarbon dating. The dominant control on fire
in this environment during the Holocene appears to be climate. Periods of climate change, identified in previous studies,
are associated with higher levels of fire activity. Fire was less ubiquitous between ~9,000 and 6,000 years BP, a period normally
described as having a higher effective moisture in south-eastern Australia. The mid-Holocene fluctuations in charcoal may
reflect anthropogenic fire, climate forcing or alternatively human responses to any climate change. Coeval changes in palaeoclimatic
sequences elsewhere and palynology at the site support a climatic explanation or that Aboriginal people used fire within a
climatic framework. 相似文献
82.
83.
Cliff I. Davidson Chris T. Hendrickson H. Scott Matthews Michael W. Bridges David T. Allen Cynthia F. Murphy Braden R. Allenby John C. Crittenden Sharon Austin 《Journal of Cleaner Production》2010,18(7):698-701
The field of engineering is changing rapidly as the growing global population puts added demands on the earth's resources: engineering decisions must now account for limitations in materials and energy as well as the need to reduce discharges of wastes. This means educators must revise courses and curricula so engineering graduates are prepared for the new challenges as practicing engineers. The Center for Sustainable Engineering has been established to help faculty members accommodate such changes through workshops and new educational materials, including a free access website with peer-reviewed materials. 相似文献
84.
Michael C. Eagle William S. Richardson Scott S. Hay Clinton Cox 《补救:环境净化治理成本、技术与工艺杂志》1993,3(3):327-344
The Office of Radiation and Indoor Air of the U.S. Environmental Protection Agency has demonstrated a soil washing plant for the treatment of radioactively contaminated soils from two Superfund sites in New Jersey. The plant employs unit operations that are widely used in the processing of minerals and coal. These operations were examined and tested to determine how they would apply to volume reduction of these contaminated soils. In this context, they are considered to be innovative candidates for remediation of other sites with large volumes of soil contaminated with low-level radioactivity. Laboratory testing of soil characteristics and behavior in unit processes is used to assess the applicability of volume reduction/chemical extraction (VORCE) technology to specific sites. 相似文献
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88.
Douglas A. Wolfe K. John Scott John R. Clayton Jr. John Lunz James R. Payne Timothy A. Thompson 《Chemistry and Ecology》1995,10(1):137-156
Standardized tests were applied to aromatic and polar fractions of sediment extracts to determine whether polar constituents or oxidative degradation products contributed significantly to the toxicity of sediments oiled by the Exxon Valdez spill. Intertidal sediment and pore-water samples were collected in September 1990 from two heavily oiled sites and an unoiled site in Prince William Sound (PWS). Methylene chloride extracts from these samples were fractionated by liquid chromatography into aliphatic, aromatic and polar fractions, and the aromatic and polar fractions were tested for toxicity using the MicrotoxR test, bivalve larval mortality and development (Mytilus); several measures of genotoxicity in Mytilus, including SOS ChromotestR, anaphase aberrations and sister chromatid exchange; and survival, anaphase aberrations and teratogenicity in coho salmon (Onchorhynchus kisutch). MicrotoxR and SOS ChromotestR protocols were applied in a screening mode to all samples, whereas other tests were applied only to selected fractions from two sites. Samples from Bay of Isles (oiled) were consistently more toxic (usually only 2 to 5-fold) than the Mooselips Bay (unoiled) samples, which gave very low responses in all tests. for both sites, however, responses to polar and aromatic fractions were about the same in most tests, suggesting that while the overall toxicity of the oil was low in these samples, at least part of that toxicity was derived from polar constituents. Compared to the parent hydrocarbons, polar oxidation products partition preferentially into pore-water and are more rapidly diluted and dispersed in the water column. These results suggest that polar oxidation products of petroleum hydrocarbons pose little risk to marine organisms, except possibly for infauna continuously exposed to pore-water in heavily oiled sediments. Independent surveys showed that sediment toxicity in PWS declined during 1989-1991 to near background levels, in accord with previous understanding of oil weathering and toxicity. 相似文献
89.
A procedure to assess the bioavailability of persistent organic pollutants (POPs) from soil samples has been developed. The procedure is based on the use of simulated in vitro gastrointestinal extraction to remove POPs from soil matrices. The level of recovery, using this approach, is assessed following liquid-liquid extraction (LLE) and analysis by gas chromatography-mass selective detection (GC-MSD). The remaining soil residue is then extracted using pressurised fluid extraction (PFE) followed by GC-MSD analysis to assess the residual fraction. The residual fraction is monitored to determine the unavailable fraction i.e. not available for absorption in the gastrointestinal tract of humans. The procedure was applied to four soil samples i.e. an aged, spiked soil and three certified reference materials (CRMs) contaminated with POPs. Recoveries of pesticides (lindane, endosulfan I, endrin, DDE, DDD and endosulfan II), phenols (cresol, TCP and PCP), and base neutral compounds (hexachloroethane, acenaphthene, dibenzofuran, fluorene and hexachlorobenzene) from aged, spiked soil following extraction with gastric fluid ranged from 0.8 to 8.3% while following intestinal extraction ranged from 5.5 to 13.5%, irrespective of POP. Recoveries of pesticides (lindane, endosulfan I, endrin, DDE, DDD and endosulfan II) from CRM 805-050 following extraction with gastric fluid were below the limit of detection while following intestinal extraction ranged from 5.3 to 12.8%. Recoveries of phenols (cresol, TCP and PCP) from CRM 401-225 following extraction with gastric fluid ranged from 1.6 to 2.0% while following intestinal extraction ranged from 4.1 to 5.4%. Recoveries of base neutral acid analytes (hexachloroethane, acenaphthene, dibenzofuran, fluorene and hexachlorobenzene) from CRM 107-100 following extraction with gastric fluid ranged from 1.4 to 4.0% while following intestinal extraction ranged from 6.6 to 12.7%. It has been found that the majority of POPs present i.e. >75%, would be excreted if consumed and not be absorbed in the gastrointestinal tract of humans. 相似文献
90.
Citrulline, one of the forms in which fixed nitrogen is assimilated in free-living blue-green algae and additionally in the blue-green algae/cycad symbiosis in Macrozamia, is similarly assimilated in the nitrogen fixing root nodules of Alnus glutinosa. By investigating the localisation of ornithine carbamoyl transferase in both cases it has been shown that in these symbiotic systems the ornithine carbamoyl transferase is only active in host tissue. This suggests that the host exerts an influence on the assimilation of fixed nitrogen in the microsymbiont resulting in the blocking of the enzyme trans-carbamylase with the subsequent excretion of the fixed nitrogen as ammonia to the host for further assimilation. This is discussed in the light of work on nitrogen metabolism in other symbiotic relationships involving nitrogen fixing organisms, where the effect of altering the habitat of the micro-organism has in fact resulted in a change in its metabolism. 相似文献