Naphthenic acids are components of most petroleums, including those found in the Athabasca Oil Sands of northeastern Alberta. Some naphthenic acids that are solubilized during bitumen extraction from oil sands are acutely toxic to a variety of organisms. Four-month enrichment cultures obtained from the rhizospheres of five plant species native to Alberta, and established with the addition of bitumen (0.5%) as the sole carbon source, revealed a high potential for aerobic degradation of a Merichem commercial preparation of naphthenic acids. Changes in the concentration and composition of the naphthenic acids mixtures during incubation were followed using high-performance liquid chromatography and gas chromatography-electron impact mass spectrometry. Concentrations did not significantly change in the sterile control, but they decreased by up to 90% after 10 days of incubation in the viable cultures. Lower molecular mass naphthenic acids were preferentially degraded, while the proportion of high molecular mass acids increased during incubation. By day 17, the most abundant ions were derived from cellular membranes, corresponding to an increase in microbial numbers in the cultures as naphthenic acids were metabolized. This study is the first to demonstrate the biodegradation potential of microorganisms from rhizosphere soils to biodegrade naphthenic acids. 相似文献
There is a need for a better understanding of the status of the environment. At the same time, concerns have been raised regarding alienation of the local populace from environmental decisions. One proposed solution is participatory environmental monitoring. When evaluating the usefulness of environmental monitoring, the focus may be on accuracy, as is usually done by scientists, or on efficiency in terms of conservation impact. To test whether investment in participatory biodiversity monitoring makes economic sense for obtaining data for management decisions, we compared the cost efficiency of participatory and conventional biodiversity monitoring methods in Philippine parks. We found that, from a government perspective, investment in monitoring that combines scientific with participatory methods is strikingly more effective than a similar level of investment in conventional scientific methods alone in generating conservation management interventions. Moreover, the local populace seemed to benefit from more secure de facto user rights over land and other resources. Participatory biodiversity monitoring not only represents a cost-effective alternative when conventional monitoring is impossible, but it is also an unexpectedly powerful complementary approach, capable of generating a much higher level of conservation management intervention, where conventional monitoring already takes place. 相似文献
Objective: This study examined the time from law enforcement dispatch to the first blood draw in cases of driving under the influence (DUI) vehicular homicide and a subset of DUI vehicular assault cases in Colorado in 2012. Laboratory toxicology results were also examined to understand the implications of delays in blood draws in cases of driving while under the influence of marijuana's delta-9-tetrahydrocannabinol (THC).
Methods: Colorado court records were reviewed and information regarding charges, presence of alcohol and/or drugs, time of law enforcement contact and blood draw, crash location, and other contextual factors were identified. The distributions of first blood draw times were studied by charge and by responding law enforcement agency. Toxicology data from a different cohort of DUI traffic arrests in Colorado and Washington were examined to determine the proportion of blood tests for THC that were above specified legal limits in those states.
Results: The average time from law enforcement dispatch to blood draw in cases of vehicular homicide and vehicular assault was 2.32 h (SD ± 1.31 h), with a range of 0.83 to 8.0 h and a median of 2.0 h. Data from DUI traffic arrests found that between 42 and 70% of all cannabinoid-positive traffic arrests tested below 5 ng/ml THC in blood, which is the legal limit in Colorado and Washington.
Conclusion: Given the current delays to blood testing in cases of arrests for vehicular homicide and vehicular assault in Colorado, many blood tests are unlikely to confirm that drivers who are impaired from smoking marijuana have THC levels above established legal limits. 相似文献
Amyoplasia is a rare, sporadic condition characterized by different degrees of maldevelopment of the skeletal muscles, which are replaced by fibrous and fatty tissue. In this report, we present a case of generalized amyoplasia presenting at 19 weeks' gestation. The most striking finding was the absence of fetal movements, resulting in severe multiple congenital contractures, hydrops, and polyhydramnios. At autopsy, histological examination of the skeletal muscle showed small groups of poorly developed fibres within areas of fat. This report suggests that generalized amyoplasia could be a common cause of severe forms of multiple congenital contractures, but is probably underdiagnosed at post-mortem because of inadequate examination of muscles. Definitive diagnosis is important in determining the risks of recurrence in these cases. 相似文献
Zein has been studied for its potential as a biobased polymeric material. Due to the fact that films made exclusively from zein are brittle, composites of zein and oleic acid were prepared in our lab and formed into flexible films. Film properties were believed related to their structure. X-ray scattering measurements on zein films suggested the formation of layers along the plane of the film. Oleic acid seemed to play an important role in layer formation. However, X-ray measurements could not yield information on the nature of the interface between oleic acid and zein. Surface plasmon resonance (SPR) was used to further investigate interaction between zein and oleic acid. Dynamic adsorption of zein from alcoholic solutions onto hydrophilic and hydrophobic surfaces generated by self-assembled monolayers of 11-mercaptoundecanoic acid or 1-octanethiol was monitored by SPR. It was observed that zein had a greater affinity for hydrophilic than for hydrophobic surfaces under the prevalent experimental conditions. A mechanism for structure development of zein-oleate films was proposed based on these results and previous X-ray measurements. It is suggested that the structure development involves hydrophilic adsorption of fatty acids onto the zein surface followed by hydrophobic associations leading to a layered film structure organization. 相似文献
ABSTRACT: Precipitation and resultant runoff were sampled for a series of storm events over the period of one year. The test site was the parking lot of a large suburban shopping mall in the Syracuse, New York, area. Both precipitation and runoff were tested for lead, zinc, copper, cadmium, and petroleum hydrocarbons: substantial amounts were detected in each. No correlation was found between precipitation contaminant concentration and the length of the antecedent dry period. A weak, but apparently inverse relationship was noticed between concentration and amount of precipitation. Poor correlations were obtained between runoff contaminant concentration and the antecedent dry period. The variability attributable to different precipitation volumes was removed by converting to a unit-area basis. The variability attributable to precipitation contaminant load was removed by subtraction. The resultant value, dryfall accumulation, then correlated well with the length of the antecedent dry period. Metal ions were found in both precipitation and runoff and were hypothesized to come from atmospheric fallout as a result of distant emissions and from very localized sources, primarily vehicle traffic on the parking facility. Petroleum residues were believed to be the sole result of automobile losses, since none could be detected in precipitation samples. 相似文献
Pregnant Long Evans rats received 1.0 μg/kg of dioxin toxic equivalents (TEQ) by oral gavage on the 15th gestational day (GD 15), using a dosing mixture that contained two polychlorinated dioxins, four polychlorinated furans and three non-ortho polychlorinated biphenyls (PCBs). Rats were sacrificed on GD 16, GD 21 and postnatal day 4 (PND 4). The lipid content of fetus, pup, placenta and maternal liver, serum and adipose tissue were determined. Treated GD 16 and GD 21 fetuses had identical lipid content to the control group, yet the lipid content of treated pups on PND 4 was 32% higher than that of the control group. On the other hand, the lipid content of placenta, liver, and serum from the treated dams was 44–50%, 24%, and 38% lower than that of the control group, respectively. Thus, a low-dose mixture of dioxin-like compounds can cause changes in lipid content. The lipid content of offspring was not affected until they were exposed via lactation. 相似文献