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51.
Gwyther CL Jones DL Golyshin PN Edwards-Jones G Williams AP 《Waste management (New York, N.Y.)》2012,32(5):933-938
The EU Animal By-Products Regulations generated the need for novel methods of storage and disposal of dead livestock. Bioreduction prior to rendering or incineration has been proposed as a practical and potentially cost-effective method; however, its biosecurity characteristics need to be elucidated. To address this, Salmonella enterica (serovars Senftenberg and Poona), Enterococcus faecalis, Campylobacter jejuni, Campylobacter coli and a lux-marked strain of Escherichia coli O157 were inoculated into laboratory-scale bioreduction vessels containing sheep carcass constituents. Numbers of all pathogens and the metabolic activity of E. coli O157 decreased significantly within the liquor waste over time, and only E. faecalis remained detectable after 3months. Only very low numbers of Salmonella spp. and E. faecalis were detected in bioaerosols, and only at initial stages of the trial. These results further indicate that bioreduction represents a suitable method of storing and reducing the volume of livestock carcasses prior to ultimate disposal. 相似文献
52.
Gareth K. Phoenix Jonathan R. Leake David J. Read J. Philip Grime John A. Lee 《Water, Air, & Soil Pollution: Focus》2005,4(6):159-167
Semi-natural calcareous and acidic grasslands are known to be sensitive to increased atmospheric N deposition. However, the fate of pollutant N within these systems is unknown. This paper reports on the first studies to determine the fate of added N within a calcareous and an acidic grassland subject to long-term simulated enhanced N deposition. Intact soil/turf cores were removed from field plots treated for six years with enhanced N deposition (ambient +0, +35 and +140 kg N ha?1 year?1). Cores were inserted into lysimeters and output fluxes of N were monitored in detail. Complete N budgets—calculated from the N flux data—showed considerable accumulation of N within the treated grasslands, up to 76% and 38% of pollutant N in the calcareous and acidic grasslands respectively. In the second study, the short-term (21 day) fate of pollutant N was determined by tracing 15N labelled ammonium nitrate (+35 kg N ha?1 year?1) though the acidic and calcareous lysimeters into plant, soil and leachate pools. Up to 91% and 59% of 15N was recovered in soils and vegetation of the calcareous and acidic grasslands respectively, with negligible amounts recovered in soil extractable ammonium and nitrate (<0.3%) and in leachate (<0.02%). This rapid short-term immobilisation of pollutant N supports the long-term accumulation of the element calculated from the N flux study. 相似文献
53.
Gareth K. Phoenix Jonathan R. Leake David J. Read J. Philip Grime John A. Lee 《Water, Air, & Soil Pollution: Focus》2004,4(6):159-167
Semi-natural calcareous and acidic grasslands are known to be sensitive to increased atmospheric N deposition. However, the fate of pollutant N within these systems is unknown. This paper reports on the first studies to determine the fate of added N within a calcareous and an acidic grassland subject to long-term simulated enhanced N deposition. Intact soil/turf cores were removed from field plots treated for six years with enhanced N deposition (ambient +0, +35 and +140 kg N ha–1 year–1). Cores were inserted into lysimeters and output fluxes of N were monitored in detail. Complete N budgets—calculated from the N flux data—showed considerable accumulation of N within the treated grasslands, up to 76% and 38% of pollutant N in the calcareous and acidic grasslands respectively. In the second study, the short-term (21 day) fate of pollutant N was determined by tracing 15N labelled ammonium nitrate (+35 kg N ha–1 year–1) though the acidic and calcareous lysimeters into plant, soil and leachate pools. Up to 91% and 59% of 15N was recovered in soils and vegetation of the calcareous and acidic grasslands respectively, with negligible amounts recovered in soil extractable ammonium and nitrate (<0.3%) and in leachate (<0.02%). This rapid short-term immobilisation of pollutant N supports the long-term accumulation of the element calculated from the N flux study. 相似文献
54.
A three-dimensional, iron-cemented structure found in the anterior thoracic cavity of articulated Thescelosaurus skeletal remains was hypothesized to be the fossilized remains of the animal’s four-chambered heart. This was important because
the finding could be interpreted to support a hypothesis that non-avian dinosaurs were endothermic. Mammals and birds, the
only extant organisms with four-chambered hearts and single aortae, are endotherms. The hypothesis that this Thescelosaurus has a preserved heart was controversial, and therefore, we reexamined it using higher-resolution computed tomography, paleohistological
examination, X-ray diffraction analysis, X-ray photoelectron spectroscopy, and scanning electron microscopy. This suite of
analyses allows for detailed morphological and chemical examination beyond what was provided in the original work. Neither
the more detailed examination of the gross morphology and orientation of the thoracic “heart” nor the microstructural studies
supported the hypothesis that the structure was a heart. The more advanced computed tomography showed the same three areas
of low density as the earlier studies with no evidence of additional low-density areas as might be expected from examinations
of an ex situ ostrich heart. Microstructural examination of a fragment taken from the “heart” was consistent with cemented
sand grains, and no chemical signal consistent with a biological origin was detected. However, small patches of cell-like
microstructures were preserved in the sandstone matrix of the thoracic structure. A possible biological origin for these microstructures
is the focus of ongoing investigation. 相似文献
55.
George Yu. Sofronov Gareth E. Evans Jonathan M. Keith Dirk P. Kroese 《Environmental Modeling and Assessment》2009,14(5):577-584
The genomes of complex organisms, including the human genome, are highly structured. This structure takes the form of segmental
patterns of variation in various properties and may be caused by the division of genomes into regions of distinct function,
by the contingent evolutionary processes that gave rise to genomes, or by a combination of both. Whatever the cause, identifying
the change-points between segments is potentially important, as a means of discovering the functional components of a genome,
understanding the evolutionary processes involved, and fully describing genomic architecture. One property of genomes that
is known to display a segmental pattern of variation is GC content. The GC content of a portion of DNA is the proportion of
GC pairs that it contains. Sharp changes in GC content can be observed in human and other genomes. Such change-points may
be the boundaries of functional elements or may play a structural role. We model genome sequences as a multiple change-point
process, that is, a process in which sequential data are separated into segments by an unknown number of change-points, with
each segment supposed to have been generated by a different process. We consider a Sequential Importance Sampling approach
to change-point modeling using Monte Carlo simulation to find estimates of change-points as well as parameters of the process
on each segment. Numerical experiments illustrate the effectiveness of the approach. We obtain estimates for the locations
of change-points in artificially generated sequences and compare the accuracy of these estimates to those obtained via Markov
chain Monte Carlo and a well-known method, IsoFinder. We also provide examples with real data sets to illustrate the usefulness
of this method. 相似文献
56.
57.
Thomas GO Farrar D Braekevelt E Stern G Kalantzi OI Martin FL Jones KC 《Environment international》2006,32(1):34-40
Chlorinated paraffins (also called polychlorinated n-alkanes -- PCAs) are a class of industrial chemicals comprising chlorinated straight chain hydrocarbons. They have a wide range of applications and are now found in a range of environmental compartments. We analysed a total of 25 human milk-fat samples, donated by 18 individuals from the urban London and more rural Lancaster areas in the UK, for short chain PCAs (C(10)-C(13) sPCAs) and medium chain PCAs (C(14)-C(17) mPCAs), using gas chromatography-ECNI high-resolution mass spectrometry. Our study confirms that trace quantities of PCAs can reach human milk-fat. sPCAs were detected in all but four samples, while mPCAs were detected in all samples. The median sPCA concentration was 180 ng/g fat (range of 49 to 820 ng/g fat -- detected values only) and the median mPCA concentration was 21 ng/g fat (range of 6.2 to 320 ng/g fat). No differences were noted in ranges of observed values for either sPCAs or mPCAs between samples from London and Lancaster. Most samples also exhibited similar patterns of sPCAs and mPCAs. One sample exhibited a different pattern for sPCAs and mPCAs, an observation that may be related to differences in exposure or biological factors for this individual. 相似文献
58.
Hansen HR Raab A Price AH Duan G Zhu Y Norton GJ Feldmann J Meharg AA 《Journal of environmental monitoring : JEM》2011,13(1):32-34
Tetramethylarsonium has for the first time been identified in a commercially grown food product, rice, constituting up to 5.8% of the total arsenic in the rice. 相似文献
59.
Wildfires are a common feature of peatland environments, but the carbon balance of these wildfires is often not considered and the production of refractory black carbon in these wildfires could be an important addition to carbon accumulation and mitigate losses of biomass during the fire. This study investigates the biomass and carbon losses during a moorland wildfire. Changes in above-ground carbon stocks were calculated using a combination of field data, laboratory measurements and literature values. The results show that approximately 14% of the carbon in the original above-ground biomass remained on the site after the burn. Black carbon production was approximately 6 gC m(-2) which constituted 4.3% of the biomass lost. The survival of biomass and black carbon may help to mitigate the loss of carbon during the fire. 相似文献