RESUMEN
Global peatlands store more carbon than is naturally present in the atmosphere1,2. However, many peatlands are under pressure from drainage-based agriculture, plantation development and fire, with the equivalent of around 3 per cent of all anthropogenic greenhouse gases emitted from drained peatland3-5. Efforts to curb such emissions are intensifying through the conservation of undrained peatlands and re-wetting of drained systems6. Here we report eddy covariance data for carbon dioxide from 16 locations and static chamber measurements for methane from 41 locations in the UK and Ireland. We combine these with published data from sites across all major peatland biomes. We find that the mean annual effective water table depth (WTDe; that is, the average depth of the aerated peat layer) overrides all other ecosystem- and management-related controls on greenhouse gas fluxes. We estimate that every 10 centimetres of reduction in WTDe could reduce the net warming impact of CO2 and CH4 emissions (100-year global warming potentials) by the equivalent of at least 3 tonnes of CO2 per hectare per year, until WTDe is less than 30 centimetres. Raising water levels further would continue to have a net cooling effect until WTDe is within 10 centimetres of the surface. Our results suggest that greenhouse gas emissions from peatlands drained for agriculture could be greatly reduced without necessarily halting their productive use. Halving WTDe in all drained agricultural peatlands, for example, could reduce emissions by the equivalent of over 1 per cent of global anthropogenic emissions.
RESUMEN
Afforestation is a significant cause of global peatland degradation. In some regions, afforested bogs are now undergoing clear-felling and restoration, often known as forest-to-bog restoration. We studied differences in water-table depth (WTD) and porewater chemistry between intact, afforested, and restored bogs at a raised bog and blanket bog location. Solute concentrations and principal component analysis suggested that water-table drawdown and higher electrical conductivity (EC) and ammonium (NH4-N) concentrations were associated with afforestation. In contrast, higher dissolved organic carbon (DOC) and phosphate (PO4-P) concentrations were associated with deforestation. Drying-rewetting cycles influenced seasonal variability in solute concentrations, particularly in shallower porewater at the raised bog location. WTD was significantly deeper in the oldest raised bog restoration site (~9 years post-restoration) than the intact bog (mean difference = 6.2 cm). However, WTD in the oldest blanket bog restoration site (~17 years post-restoration), where furrows had been blocked, was comparable to the intact bog (mean difference = 1.2 cm). When averaged for all porewater depths, NH4-N concentrations were significantly higher in the afforested than the intact sites (mean difference = 0.77 mg L-1) whereas significant differences between the oldest restoration sites and the intact sites included higher PO4-P (mean difference = 70 µg L-1) in the raised bog and higher DOC (mean difference = 5.6 mg L-1), EC (mean difference = 19 µS cm-1) and lower SUVA254 (mean difference = 0.13 L mg-1 m-1) in the blanket bog. Results indicate felled waste (brash) may be a significant source of soluble C and PO4-P. Mean porewater PO4-P concentrations were between two and five times higher in furrows and drains in which brash had accumulated compared to other locations in the same sites where brash had not accumulated. Creating and maintaining brash-free buffer zones may therefore minimise freshwater impacts.
RESUMEN
Peatlands are important sources of fluvial carbon. Previous research has shown that riverine dissolved organic carbon (DOC) concentrations are largely controlled by soil type. However, there has been little work to establish the controls of riverine DOC within blanket peatlands that have not undergone major disturbance from drainage or burning. A total of 119 peatland catchments were sampled for riverine DOC and water colour across three drainage basins during six repeated sampling campaigns. The topographic characteristics of each catchment were determined from digital elevation models. The dominant vegetation cover was mapped using 0.5m resolution colour infrared aerial images, with ground-truthed validation revealing 82% accuracy. Forward and backward stepwise regression modelling showed that mean slope was a strong (and negative) determinant of DOC and water colour in blanket peatland river waters. There was a weak role for plant functional type in determining DOC and water colour. At the basin scale, there were major differences between the models depending on the basin. The dominance of topographic predictors of DOC found in our study, combined with a weaker role of vegetation type, paves the way for developing improved planning tools for water companies operating in peatland catchments. Using topographic data and aerial imagery it will be possible to predict which tributaries will typically yield lower DOC concentrations and which are therefore more suitable and cost-effective as raw water intakes.
RESUMEN
Discolouration of natural surface waters due to the humic component of dissolved organic carbon (DOC) is a costly problem for water supply companies. This paper reviews what is known about the impacts of prescribed moorland vegetation burning on water colour. Relevant research has taken place at three scales: laboratory experiments on peat cores, plot scale sampling of soil waters and catchment scale sampling of stream waters. While laboratory studies suggest burning increases colour production, the evidence from catchment and plot studies is contradictory. Plot studies suggest colour production may decrease or remain unchanged following burning although there is evidence for some transient changes. Catchment studies suggest prescribed moorland burning causes stream water colour to increase, although in most cases the evidence is not clear cut since most studies could not clearly disentangle the effects of burning from those of vegetation cover. The differences in findings between plot and catchment studies may be explained by: i) the short-term nature of some studies which do not measure long-term response and recovery times to burning; ii) the lack of colour measurements from shallow soil depths which contribute more to streamflow than soil water from deeper in the peat; and iii) the possibility of hydrological interactions occurring between different experimental plots at some sites. Additionally, the increase in recent patch burning in some catchments that has been statistically attributed by some authors to increases in stream water colour cannot be reconciled with theoretical calculations. When dilution with waters derived from other parts of the catchment are taken into account, large values of colour have to be theoretically derived from those recently burnt areas that occupy a small proportion of the catchment area in order to balance the change in stream water colour observed in recent years. Therefore, much further process-based work is required to properly investigate whether prescribed vegetation burning is a direct driver of enhanced colour and DOC in upland streams, rivers and lakes.
Asunto(s)
Color , Incendios , Agua Dulce , Calidad del Agua , Carbono , Agua Subterránea , Lagos , Ríos , SueloRESUMEN
Concentrations of dissolved organic carbon have increased in many, but not all, surface waters across acid impacted areas of Europe and North America over the last two decades. Over the last eight years several hypotheses have been put forward to explain these increases, but none are yet accepted universally. Research in this area appears to have reached a stalemate between those favouring declining atmospheric deposition, climate change or land management as the key driver of long-term DOC trends. While it is clear that many of these factors influence DOC dynamics in soil and stream waters, their effect varies over different temporal and spatial scales. We argue that regional differences in acid deposition loading may account for the apparent discrepancies between studies. DOC has shown strong monotonic increases in areas which have experienced strong downward trends in pollutant sulphur and/or seasalt deposition. Elsewhere climatic factors, that strongly influence seasonality, have also dominated inter-annual variability, and here long-term monotonic DOC trends are often difficult to detect. Furthermore, in areas receiving similar acid loadings, different catchment characteristics could have affected the site specific sensitivity to changes in acidity and therefore the magnitude of DOC release in response to changes in sulphur deposition. We suggest that confusion over these temporal and spatial scales of investigation has contributed unnecessarily to the disagreement over the main regional driver(s) of DOC trends, and that the data behind the majority of these studies is more compatible than is often conveyed.
Asunto(s)
Carbono/análisis , Agua Dulce/química , Contaminantes Químicos del Agua/análisis , Lluvia Ácida , Cinética , Lluvia , Temperatura , Tiempo , Contaminación Química del Agua/estadística & datos numéricosRESUMEN
Waters derived from remote 'wilderness' locations have been assumed to be largely free of bacterial contamination and thus such, near-pristine, protected catchments, unused for agriculture, have been first in the multiple line of protection (pristine catchment-long storage-treatment-disinfection) employed by the water industry. This assumption is challenged by a bacterial survey of the waters derived from the New Cairngorm National Park, Scotland. Over 480 spot samples were taken for 59 sites between March 2001 and October 2002 during nine field campaigns each of three to five days duration. Over 75% of samples tested positive for Escherichia coli (E. coli) and 85% for total coliforms. Concentrations displayed both temporal and spatial patterns. Largest values occurred over the summer months and particularly at weekends at sites frequented by visitors, either for 'wild' camping or day visits, or where water was drawn from the river for drinking. Overall the spatial and temporal variations in bacterial concentrations suggest a relationship with visitor numbers and in particular wild camping. The implications of the results for drinking water quality and visitors health are discussed along with possible management options for the area in terms of improving the disposal of human waste.
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Ríos/microbiología , Microbiología del Agua , Contaminación del Agua , Vida Silvestre , Conservación de los Recursos Naturales , Enterobacteriaceae/aislamiento & purificación , Monitoreo del Ambiente , Escherichia coli/aislamiento & purificación , Heces/microbiología , Humanos , EscociaRESUMEN
The concentration of nitrogen (N), particularly as nitrate (NO3-N), in upland streams, lakes and rivers is frequently used as a diagnostic of the vulnerability of upland ecosystems to increased atmospheric nitrogen deposition and N saturation. The N content of running waters, however, is generally assessed on the basis of sampling at a limited number of points in space and time within the catchment under investigation. The current study was conducted at Trout Beck, an 11.5 km2 blanket peat-dominated catchment in the North Pennine uplands of the UK. Results from sampling at 33 sites within this catchment demonstrated that the concentrations of all dissolved N species were highly variable, even over short distances. Statistical relationships between the concentrations of NO3-N and dissolved organic nitrogen (DON) and percentage catchment cover of Calluna/Eriophorum and Eriophorum vegetation were found. However, it was also noted that in catchments containing limestone outcrops, NO3-N concentration was much higher than in catchments where runoff was sourced directly from the blanket peat surface. It is possible that NH4-N and DON leached from the blanket peat are mineralised and nitrified, providing a source for the NO3-N found in the river channels. Overall, the current study suggests that interpretations of N-saturation based on river water chemistry measurements at a single point must be treated cautiously, and that the influence of catchment-scale physical factors, such as vegetation and geology cover on the concentration of dissolved N species in upland river waters should not be ignored.
Asunto(s)
Nitratos/análisis , Nitrógeno/análisis , Compuestos de Amonio Cuaternario/análisis , Contaminantes Químicos del Agua/análisis , Calcio/análisis , Carbonato de Calcio , Calluna , Cyperaceae , Monitoreo del Ambiente , Ríos , Suelo , Reino Unido , Abastecimiento de AguaRESUMEN
The concept of a basic (i.e., essential) medical emergency kit suitable for a general dental practitioner varies somewhat between different authorities. A practitioner's choice is also dependant on the proximity of medical aid and the nature of the dental practice. Over recent years the trend has been to restrict the items to a minimum, in the interest of both common sense and safety, for example, just oxygen, adrenaline 1:1000, an oral carbohydrate source, glyceryl trinitrate and aspirin as first options. Ancillary equipment should include an oxygen therapy facemask, a pocket mask and a set of oral (Guedel) airways. Two further medication options for consideration are an aerosol bronchodilator and, in certain circumstances, an injectable antihypoglycaemic agent. This paper provides a selective overview of the subject. An absolute necessity is for dentists to be competent in Basic Life Support skills, and to maintain a complete and current medical history for all patients.
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Odontólogos , Tratamiento de Urgencia/instrumentación , Preparaciones Farmacéuticas , Adrenérgicos , Aspirina , Broncodilatadores , Reanimación Cardiopulmonar , Epinefrina , Glucosa , Humanos , Hipoglucemiantes , Máscaras Laríngeas , Máscaras , Nitroglicerina , Terapia por Inhalación de Oxígeno , Inhibidores de Agregación Plaquetaria , VasodilatadoresRESUMEN
If a dental patient develops chest pain it must always be managed promptly and properly, i.e., the practitioner immediately stops the procedure and, being aware of the patient's medical history, questions the patient regarding the nature of the pain to help determine the likely diagnosis. It will most likely be a manifestation of coronary artery disease (synonymous with ischaemic heart disease), i.e., angina pectoris or acute myocardial infarction, most usually the former. Angina will usually resolve with proper intervention whereas up to about one-half of myocardial infarction cases will develop cardiac arrest, mostly in the first few hours, and this will be fatal in up to two-thirds of cases. As health care professionals, dental practitioners have an inherent duty of care to be able to initiate appropriate care if such a medical emergency occurs.
Asunto(s)
Angina de Pecho/diagnóstico , Atención Odontológica , Angina de Pecho/tratamiento farmacológico , Tratamiento de Urgencia , Humanos , Anamnesis , Infarto del Miocardio/diagnóstico , Infarto del Miocardio/prevención & controlRESUMEN
Cardiac arrest is a very rare event in a dental patient. However, practitioners have a duty of care to their patients if ever such an event occurs. The cardiac arrest discussed in this case report occurred in an elderly person with an implanted pacemaker whilst undergoing restorative dental treatment. Cardiac arrest was diagnosed and cardiopulmonary resuscitation instituted immediately, followed within three minutes by successful defibrillation using the School's semi-automatic defibrillator.
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Cardioversión Eléctrica , Paro Cardíaco/terapia , Anciano , Reanimación Cardiopulmonar , Atención Dental para Enfermos Crónicos , Paro Cardíaco/etiología , Humanos , Masculino , Infarto del Miocardio/complicaciones , Marcapaso Artificial , Fibrilación Ventricular/etiología , Fibrilación Ventricular/terapiaRESUMEN
Acute heart failure is a life-threatening medical emergency, most commonly occurring as an immediate or delayed complication of acute myocardial infarction (AMI), or resulting from severe hypertension or valvular defects (stenosis or incompetence). Occasionally it is caused by patients' non-compliance with medication orders. In this case the patient had a history of three previous AMIs, controlled hypertension, and controlled congestive heart failure (CHF) for which he took two 40 mg frusemide tablets (a very potent oral diuretic) each morning. Because he had experienced bladder discomfort during the latter stages of previous appointments he decided to delay taking the diuretic until after his appointment and acute heart failure ensued.
Asunto(s)
Diuréticos/administración & dosificación , Furosemida/administración & dosificación , Insuficiencia Cardíaca/tratamiento farmacológico , Enfermedad Aguda , Atención Dental para Enfermos Crónicos , Tratamiento de Urgencia , Humanos , Masculino , Persona de Mediana Edad , Cooperación del PacienteRESUMEN
Embryonic inland silversides, Meinida beryllina, were exposed to neutral, water-soluble fractions (WSFs) resulting from microbial degradation of artificially weathered Alaska North Slope (ANS) crude oil. Three individual microbes obtained from Prince William Sound, Alaska, and designated Phe#6 (enriched on phenanthrene), Hexaco#2 (enriched on the straight-chain alkane, hexacosane), and EI2V (grown by enrichment on Bushnell-Haas medium containing 0.2% pristane, a branched alkane) were used to individually biodegrade weathered ANS crude oil for 14 days in darkness in 20-L glass carboys containing nutrient enriched, sterilized 20% salinity sea water at 20 +/- 1 degrees C. Neutral WSFs resulting from biodegradation of ANS (lot 521) by each microbe were recovered and weighted. Neutral WSFs recovered were: 1.76 mg/L for Phe#6, 1.85 mg/L for Hexaco#2, and 13.02 mg/L for the EI2V microbe. Embryo toxicity and teratogenicity tests revealed that exposure of embryos to the WSFs from the EI2V incubation (with a total recovered neutral fraction approximately seven times greater than the Phe#6 and Hexaco#2 incubations) resulted in the most severe responses in craniofacial, cardiovascular, and skeletal organ systems. The total neutral WSFs recovered from the EI2V biodegradation of weathered ANS 521 were subfractionated into saturated (eluted with hexane), aromatic (eluted with CH2Cl2), polar (eluted with ethyl ether), and recombined (saturated + aromatic + polar) fractions. Developing fish embryos were then exposed to each subfraction and the recombined subfractions. The polar subfraction and recombined subfractions proved to be the most embryo toxic and teratogenic. They resulted in statistically significant (p < or = 0.05) responses (compared to controls) for craniofacial, cardiovascular, skeletal, and total severity effects in one or both tests with these subfractions.
Asunto(s)
Anomalías Congénitas/etiología , Anomalías Congénitas/veterinaria , Peces , Petróleo/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Biodegradación Ambiental , Embrión no Mamífero/efectos de los fármacos , Desarrollo Embrionario y Fetal/efectos de los fármacosRESUMEN
The nitrogen (N) composition of streams draining four upland regions of Scotland was compared in samples collected monthly between April 1997 and April 1998. Stream samples were analysed for total N (TN), particulate N (PN), nitrate (NO3), ammonium (NH4), dissolved organic N (DON) and dissolved organic carbon (DOC). Concentrations of TN were small, generally less than 1 mg l(-1) , dominated by dissolved forms of N, and varied significantly between upland regions. Nitrate accounted for most of the variability in TN; largest concentrations were observed in the Southern Uplands and smallest concentrations were observed in the Highlands. Nitrate concentrations were positively correlated with the percentage cover of improved grasslands and brown forest soils and negatively correlated with the percentage cover of peat. Concentrations of DON also varied between regions, but to a lesser extent than those of NO3. Largest concentrations occurred in SW Scotland and smallest concentrations in the Cairngorms. Although a significant positive correlation between DON and DOC was observed, stream water DON content was not related to the percentage cover of peat in the catchment, as was the case for DOC. The average DOC:DON ratio was narrower for streams in the Southern Uplands than for those in the Cairngorms and Highlands. Nitrate and DON displayed contrasting seasonal trends; NO3 concentrations were larger in the winter while DON concentrations were larger in the summer. Only a small proportion, < 8% and < 7%, of TN was PN and NH4, respectively, the majority of N was present as either NO3 or DON. Nitrate was the dominant fraction (58-65%) in all regions except the Highlands where DON accounted for 57% of TN. However, the relative importance of the DON component increased in the summer in all regions. This study has demonstrated that the DON fraction is an important component of the total N transported by streams from upland catchments in Scotland. Thus, assessments of anthropogenic impacts on N losses from upland ecosystems need to consider not only the dissolved inorganic species but also DON.
Asunto(s)
Monitoreo del Ambiente , Nitrógeno/análisis , Contaminantes del Agua/análisis , Agricultura , Carbono/análisis , Ecosistema , Humanos , Nitrógeno/metabolismo , Escocia , Estaciones del Año , SueloRESUMEN
The nitrogen (N) composition of streams draining eight upland regions of Britain was compared using monthly samples collected between April 1997 and April 1998. Stream samples were analysed for total N (TN), particulate N (PN), nitrate (NO3), ammonium (NH4), and dissolved organic nitrogen (DON). Concentrations of TN were small, generally less than 1.5 mg N l(-1), were dominated by dissolved forms of N, and varied significantly between regions. NO3 accounted for the majority of variability. Concentrations of DON also varied between regions but to a smaller extent than those of NO3. There were considerable variations in TN fluxes between upland regions, which ranged between 3.8 and 16.1 kg N ha(-1) year(-1). The majority of the variation was due to NO3 fluxes, which were largest in regions receiving largest inputs of atmospheric N deposition and ranged between 1.4 and 13.5 kg N ha(-1) year(-1). Fluxes of DON ranged between 1 and 3.5 kg N ha(-1) year( -1), while fluxes of PN were generally less than 0.5 kg N ha(-1) year(-1) , and NH4 fluxes ranged between 0.1 and 0.4 kg N ha(-1) year(-1). NO3 was the dominant fraction (47-84%) of N exported from all upland regions except the Highlands, where DON accounted for 52% of the TN flux. This study has shown that the DON fraction is an important component of the total N transported by upland streams in Britain.
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Ecosistema , Nitrógeno/análisis , Altitud , Amoníaco/análisis , Agua Dulce/análisis , Geografía , Nitratos/análisis , Estaciones del Año , Reino UnidoRESUMEN
The ARBRE (ARable Biomass Renewable Energy) project, the first large-scale wood-fueled electricity generating plant in the U.K., represents a significant development in realising British and European policy objectives on renewable energy. The plant is fueled by a mix of wood from short rotation coppice (SRC) and forest residues. Where feasible, composted/conditioned sewage sludge is applied to coppice sites to increase yields and improve soil structure. In the Yorkshire Water region, typical total N:P:K composition of composted/conditioned sludge is 2.9:3.8:0.3, respectively. Sludge application is calculated on the basis of total nitrogen (N) content to achieve 750 kg N ha(-1), for 3 years" requirement. Willow coppice forms a dense, widely spaced, root network, which, with its long growing season, makes it an effective user of nutrients. This, in combination with willow"s use as a nonfood, nonfodder crop, makes it an attractive route for the recycling of sewage sludge in the absence of sea disposal, banned under the EC Urban Waste Water Treatment Directive (UWWTD). Further work is required on the nutritional requirements of SRC in order to understand better the quantities of sludge that can be applied to SRC without having a detrimental impact on the environment. This paper suggests the source of N rerouting under the UWWTD and suggests the likely expansion of SRC as an alternative recycling pathway.
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Biomasa , Conservación de los Recursos Naturales/métodos , Fuentes Generadoras de Energía/estadística & datos numéricos , Nitrógeno , Eliminación de Residuos Líquidos/métodos , Nitrógeno/análisis , Salix , Aguas del Alcantarillado/estadística & datos numéricos , Reino Unido , Eliminación de Residuos Líquidos/estadística & datos numéricosRESUMEN
Artificially weathered crude oil was degraded by four diverse cultures of mixed marine bacteria under optimized conditions for 7 and 14 days. Loss in total weight of starting oil (30 g) ranged from 6.8-17.3% in biologically active incubations compared with only 0. 9-1.1% in sterile and nutrient-limited controls. In all incubations, both neutral and acidic water-soluble fractions (WSF) were accumulated. In biologically active systems, 50.9-249.0 mg neutral and 63.3-406.8 mg acidic WSF were accumulated whereas only 6.5-11.1 mg neutral and 1.7-2.2 mg acidic WSF were accumulated in control incubations. Analysis by gas chromatography demonstrated that accumulated WSF in biologically active systems contained compounds different from those washed from the starting crude oil. Exposure of grass shrimp (Palaemonetes pugio) embryos to neutral WSF from each of the biologically active cultures resulted in high embryo mortalities relative to sterile and nutrient-limited controls which exhibited >90% hatching success and larval survival. Toxicity of neutral WSF was also demonstrated on larvae of mysids (Mysidopsis bahia). In both cases, toxicity occurred only on exposure to neutral material accumulated by active, oil-degrading cultures and not with material washed from the weathered crude oil. These results imply that unique compounds were accumulated during degradation that may have been responsible for increased toxicity.
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Bacterias/metabolismo , Crustáceos/efectos de los fármacos , Petróleo/metabolismo , Petróleo/toxicidad , Contaminantes Químicos del Agua/metabolismo , Contaminantes Químicos del Agua/toxicidad , Animales , Océano Atlántico , Biodegradación Ambiental , Decápodos/efectos de los fármacos , Florida , SolubilidadRESUMEN
[1-13C]acenaphthene, a tracer compound with a nuclear magnetic resonance (NMR)-active nucleus at the C-1 position, has been employed in conjunction with a standard broad-band-decoupled 13C-NMR spectroscopy technique to study the biodegradation of acenaphthene by various bacterial cultures degrading aromatic hydrocarbons of creosote. Site-specific labeling at the benzylic position of acenaphthene allows 13C-NMR detection of chemical changes due to initial oxidations catalyzed by bacterial enzymes of aromatic hydrocarbon catabolism. Biodegradation of [1-13C]acenaphthene in the presence of naphthalene or creosote polycyclic aromatic compounds (PACs) was examined with an undefined mixed bacterial culture (established by enrichment on creosote PACs) and with isolates of individual naphthalene- and phenanthrene-degrading strains from this culture. From 13C-NMR spectra of extractable materials obtained in time course biodegradation experiments under optimized conditions, a number of signals were assigned to accumulated products such as 1-acenaphthenol, 1-acenaphthenone, acenaphthene-1,2-diol and naphthalene 1,8-dicarboxylic acid, formed by benzylic oxidation of acenaphthene and subsequent reactions. Limited degradation of acenaphthene could be attributed to its oxidation by naphthalene 1,2-dioxygenase or related dioxygenases, indicative of certain limitations of the undefined mixed culture with respect to acenaphthene catabolism. Coinoculation of the mixed culture with cells of acenaphthene-grown strain Pseudomonas sp. strain A2279 mitigated the accumulation of partial transformation products and resulted in more complete degradation of acenaphthene. This study demonstrates the value of the stable isotope labeling approach and its ability to reveal incomplete mineralization even when as little as 2 to 3% of the substrate is incompletely oxidized, yielding products of partial transformation. The approach outlined may prove useful in assessing bioremediation performance.
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Acenaftenos/metabolismo , Bacterias/metabolismo , Creosota/metabolismo , Combustibles Fósiles/análisis , Hidrocarburos Policíclicos Aromáticos/metabolismo , Bacterias/aislamiento & purificación , Biodegradación Ambiental , Isótopos de Carbono , Espectroscopía de Resonancia Magnética , Naftalenos/metabolismo , Pseudomonas/aislamiento & purificación , Pseudomonas/metabolismo , Microbiología del Suelo , Contaminantes del Suelo/metabolismoRESUMEN
Weathered Alaska North Slope crude oil (ANS 521) was subjected to biodegradation in vigorously stirred incubations for 14 days at 15 +/- 1 degrees C in 20/1000 salinity sterilized seawater, amended with nutrients and inoculated with a hydrocarbon-degrading microorganism (EI2V) isolated from an oil-contaminated beach in Prince William Sound, Alaska. A total of 13.7 mg/L water-soluble neutral fraction (WSF) was recovered from the incubation of weathered ANS 521. Toxicity/ teratogenicity tests were conducted with WSF recovered from the biodegradation system using embryonic and larval Pacific herring, Clupea pallasi. Exposures were begun at 4, 48, and 96 h postfertilization of herring eggs. Exposure concentrations were 1, 10, and 100% of the original concentration of WSF recovered from incubations (redissolved in 20/1000 salinity sterile seawater at 15 +/- 1 degrees C). Sterile 20/1000 salinity seawater without the addition of redissolved neutral fraction was used as a control. Significant (p < or = 0.05) embryo mortality or teratogenic responses were observed at WSF concentrations of 10 and 100%. On days 5 through 8 of embryogenesis, counts of heart contraction rates were significantly lower (p < or = 0.05) at the 100% WSF concentration for embryos exposed beginning at 4 and 48 h postfertilization. Grow-out of larvae from selected exposures was conducted. High mortality was noted in larvae exposed to the 10% WSF concentration beginning at 4 and 48 h postfertilization. Most of these larvae died 5 to 8 days after hatching when they elicited vertebral displacements at a time concurrent with the onset of feeding behavior.
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Desarrollo Embrionario , Peces/embriología , Petróleo/toxicidad , Contaminación del Agua/efectos adversos , Animales , Biodegradación Ambiental , Larva/crecimiento & desarrollo , Pruebas de ToxicidadRESUMEN
This is a report of a postal questionnaire survey of 1250 general dental practitioners regarding occurrence of medical emergencies and their choice of emergency drugs and equipment. The response rate was 65 per cent and the results showed that about one in seven practitioners had had to resuscitate a patient. The most common medical emergencies were adverse reactions to local anaesthetics, grand mal seizures, angina pectoris and hypoglycaemia (insulin shock). Nearly all respondents (96 per cent) believed that dentists need to be competent in cardiopulmonary resuscitation, just over a half (55 per cent) felt they were competent in CPR on graduation and a similar figure (57 per cent) felt they could perform effective single person CPR for five minutes. Almost two-thirds (64 per cent) had undertaken CPR courses since graduation. Additionally, the most commonly kept emergency drugs were oxygen (63 per cent) and adrenaline (22 per cent), while the most commonly kept emergency equipment was a manual resuscitator (recoil bag-valve-mask type) which was kept by 27 per cent of the practitioners.
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Atención Odontológica , Odontólogos , Urgencias Médicas , Equipos y Suministros , Preparaciones Farmacéuticas , Anestésicos Locales/efectos adversos , Angina de Pecho/fisiopatología , Australia , Reanimación Cardiopulmonar/educación , Competencia Clínica , Epilepsia Tónico-Clónica/fisiopatología , Epinefrina , Odontología General , Humanos , Hipoglucemia/fisiopatología , Incidencia , Oxígeno , Resucitación/educación , Resucitación/instrumentaciónRESUMEN
Weathered Alaska North Slope crude oil (ANS 521) was stirred for 2 and 14 days in 20 per thousand salinity sterile seawater or for 14 days in seawater with nutrients and a group of three (GO3) microorganisms from Prince William Sound, Alaska, that were capable of biodegrading hydrocarbons. A total of 0.65 and 0.69 mg/L water soluble fraction (WSF) of neutral fraction hydrocarbons was recovered from the 2- and 14-day stirred sterile systems, respectively. In comparison, a total of 7.5 mg/L WSF neutral fraction hydrocarbons was recovered from systems containing ANS 521 that were stirred and biodegraded by the GO3 microbes for 14 days. Toxicity/teratogenicity tests were conducted with neutral fraction hydrocarbons recovered from the sterile and biodegraded systems using embryonic inland silversides, Menidia beryllina. Hydrocarbons from the sterile systems did not cause statistically significant teratogenic responses at concentrations of 1%, 10%, and 100% (w/v) of recovered fractions (redissolved in 20 per thousand salinity sterile seawater). Counts of heart contraction rates were significantly lower (alpha=0.05) at the 100% WSF concentration of hydrocarbons on days 5 and 6 of embryogenesis. In contrast, recovered and redissolved neutral fraction hydrocarbons from ANS 521, that were biodegraded for 14 days, caused statistically significant (alpha=0.05) teratogenic responses at the 1, 10, and 100% WSF concentrations. Measurement of heart contraction rates showed statistically significant (alpha=0.05) reductions at the 100% WSF concentration on days 2 through 6 of embryogenesis, compared to controls.