969 resultados para country rock instantaneous point source solld-llquid interface
Resumo:
Migmatization of gabbroic rocks at 2-3 kbar has occurred in the metamorphic contact aureole of a mafic pluton in the Fuerteventura Basal Complex (Canary Island;). Migmatites are characterized by a dense network: of closely spaced millimetre-wide leucocratic veins with perfectly preserved igneous textures. They are all relatively enriched in Al, Na I: Sr Ba, Nb, Y and the rare earth elements compared with the unaffected country rock beyond the aureole. Migmatization under such low-pressure conditions war possible because of the unusual tectonic and magmatic contact in which ii occurred. Multiple basic intrusions associated with extrusive volcanic activity created high heat flow in a small area. Alkaline and metasomatized rocks present in the country rock of the intruding pluton were leached by high-temperature fluids during contact metamorphism. These enriched fluids then favoured partial melting of the host gabbroic rocks, and contaminated both the leucosomes and melanosomes. A transpressive tectonic setting at the time of intrusion created shearing along the contact between the intrusion and its host rock. This shearing enhanced circulation of the fluids and allowed segregation of the nea-formed melts from their restite by opening tension veins into which the melts migrated. Depending on the relative timing of melt segregation and recrystallization leucosomes range in composition from a 40-60% mixture of clinopyroxene (+/- amphibole) and plagioclase to almost pure feldspathic veins. Comparable occurrences of gabbros migmatized at low pressure are expected only at a snail scale in localized areas of high heat flow in the presence of fluids, such as in. mid-ocean ridges or ocean-islands.
Resumo:
After a study of the population dynamics of Biomphalaria glabrata snails in several breeding places in the Dominican Republic, the snail Thiara granifera was introduced in some B. glabrata habitats. T. granifera became established in one point in one habitat in the townof Quisqueya, in the east of the country. Around this point of establishment 6 points were selected in order to observe the population dynamics of both species of snails and the chemical and biological characteristics at each point. Four of these points already harbored B. glabrata. One control point was selected also harboring B. glabrata. After 14 months of observations, the results showed that T. granifera was competing with and displacing B. glabrata. This competition does not seem to be competition for food or vital space. Rather, B. glabrata avoids the presence of T. granifera and moves away to new areas, and this is possibly due to a chemical substance(s) secreted by T. granifera or by physical contact with the large number of individuals of T. granifera.
Resumo:
Natural environments are constantly challenged by the release of hydrophobic organic contaminants, which represent a threat for both the ecosystem and human health. Despite a substantial degradation by naturally occurring micro-organisms, a non negligible fraction of these pollutants tend to persist in soil and sediments due to their reduced accessibility to microbial degraders. This lack of 'bioavailability' is acknowledged as a key parameter for the natural and stimulated clean-up (bioremediation) of contaminated sites. We developed a bacterial bioreporter that responds to the presence of polyaromatic hydrocarbons (PAHs) by the production of the green fluorescent protein (GFP), based on the PAH-degrading bacterium Burkholderia sartisoli. We showed in this study that the bacterial biosensor B. sartisoli strain RP037 was faithfully reporting the degradation of naphthalene and phenanthrene (two PAHs of low molecular weight) via the production of GFP. What is more, the magnitude of GFP induction was influenced by change in the PAH flux triggered by a variety of physico-chemical parameters, such as the contact surface between the pollutant and the aqueous suspension. Further experiments permitted to test the influence of dissolved organic matter, which is an important component of natural habitats and can interact with organic pollutants. In addition, we tested the influence of two types of biosurfactants (tensio-active agents produced by living organisms) on phenanthrene's degradation by RP037. Interestingly, the surfactant's effects on the biodegradation rate appeared to depend on the type of biosurfactant and probably on the type of bacterial strain. Finally, we tagged B. sartisoli strain RP037 with a constitutively expressed mCherry fluorescent protein. The presence of mCherry allowed us to visualize the bacteria in complex samples even when GFP production was not induced. The new strain RP037-mChe embedded in a gel patch was used to detect PAH fluxes from a point source, such as a non-aqueous liquid or particles of contaminated soil. In parallel, we also developed and tested a so-called multiwell bacterial biosensor platform, which permitted the simultaneous use of four different reporter strains for the detection of major crude oil components (e.g., saturated hydrocarbons, mono- and polyaromatics) in aqueous samples. We specifically constructed the strain B. sartisoli RP007 (pPROBE-phn-luxAB) for the detection of naphthalene and phenanthrene. It was equipped with a reporter plasmid similar to the one in strain RP037, except that the gfp gene was replaced by the genes luxAB, which encoded the bacterial luciferase. The strain was implemented in the biosensor platform and detected an equivalent naphthalene concentration in oil spilled-sea water. We also cloned the gene for the transcriptional activator AlkS and the operator/promoter region of the operon alkSB1GHJ from the alkane-degrader bacterium Alcanivorax borkumensis strain SK2 in order to construct a new bacterial biosensor with higher sensitivity towards long-chain alkanes. However, the resulting strain showed no increased light emission in presence of tetradecane (C14), while it still efficiently reported low concentrations of octane (C8). RSUM : Les cosystmes naturels sont constamment exposs nombre de contaminants organiques hydrophobes (COHs) d'origine industrielle, agricole ou mme naturelle. Les COHs menacent la fois l'environnement, le bien-tre des espces animales et vgtales et la sant humaine, mais ils peuvent tre dgrads par des micro-organismes tels que les bactries et les champignons, qui peuvent tre capables des les transformer en produits inoffensifs comme le gaz carbonique et l'eau. La biodgradation des COHs est cependant frquemment limite par leur pauvre disponibilit envers les organismes qui les dgradent. Ainsi, bien que la biodgradation opre partiellement, les COHs persistent dans l'environnement de faibles concentrations qui potentiellement peuvent encore causer des effets toxiques chroniques. Puisque la plupart des COHs peuvent tre mtaboliss par l'activit microbienne, leur persistance a gnralement pour origine des contraintes physico-chimiques plutt que biologiques. Par exemple, leur solubilit dans l'eau trs limite rduit leur prise par des consommateurs potentiels. De plus, l'adsorption la matire organique et la squestration dans les micropores du sol participent rduire leur disponibilit envers les microbes. Les processus de biodisponibilit, c'est--dire les processus qui gouvernent la dissolution et la prise de polluants par les organismes vivants, sont gnralement perus comme des paramtres cls pour la dpollution (bioremdiation) naturelle et stimule des sites contamins. Les hydrocarbures aromatiques polycycliques (HAPs) sont un modle de COH produits par les activits aussi bien humaines que naturelles, et lists comme des contaminants chroniques de l'air, des sols et des sdiments. Ils peuvent tre dgrads par un vaste nombre d'espces bactriennes mais leur taux de biodgradation est souvent limit par les contraintes mentionnes ci-dessus. Afin de comprendre les processus de biodisponibilit pour les cellules bactriennes, nous avons dcid d'utiliser les bactries elles-mmes pour dtecter et rapporter les flux de COH. Ceci a t ralis par l'application d'une stratgie de conception visant produire des bactries `biocapteurs-rapporteurs', qui littralement s'allument lorsqu'elles dtectent un compos cible pour lequel elles ont t conues. En premier lieu, nous nous sommes concentrs sur Burkholderia sartisoli (souche RP007), une bactrie isole du sol et consommatrice de HAP .Cette souche a servi de base la construction d'un circuit gntique permettant la formation de la protine autofluorescente GFP ds que les cellules dtectent le naphtalne ou le phnanthrne, deux HAP de faible masse molculaire. En effet, nous avons pu montrer que la bactrie obtenue, la souche RP037 de B. sartisoli, produit une fluorescence GFP grandissante lors d'une exposition en culture liquide du phnanthrne sous forme cristalline (0.5 mg par ml de milieu de culture). Nous avons dcouvert que pour une induction optimale il tait ncessaire de fournir aux cellules une source additionnelle de carbone sous la forme d'actate, ou sinon seul un nombre limit de cellules deviennent induites. Malgr cela, le phnanthrne a induit une rponse trs htrogne au sein de la population de cellules, avec quelques cellules pauvrement induites tandis que d'autres l'taient trs fortement. La raison de cette htrognit extrme, mme dans des cultures liquides mlanges, reste pour le moment incertaine. Plus important, nous avons pu montrer que l'amplitude de l'induction de GFP dpendait de paramtres physiques affectant le flux de phnanthrne aux cellules, tels que : la surface de contact entre le phnanthrne solide et la phase aqueuse ; l'ajout de surfactant ; le scellement de phnanthrne l'intrieur de billes de polymres (Model Polymer Release System) ; la dissolution du phnanthrne dans un fluide gras immiscible l'eau. Nous en avons conclu que la souche RP037 dtecte convenablement des flux de phnantrne et nous avons propos une relation entre le transfert de masse de phnanthrne et la production de GFP. Nous avons par la suite utilis la souche afin d'examiner l'effet de plusieurs paramtres chimiques connus dans la littrature pour influencer la biodisponibilit des HAP. Premirement, les acides humiques. Quelques rapports font tat que la disponibilit des HAP pourrait tre augmente par la prsence de matire organique dissoute. Nous avons mesur l'induction de GFP comme fonction de l'exposition des cellules RP037 au phnanthrne ou au naphtalne en prsence ou absence d'acides humiques dans la culture. Nous avons test des concentrations d'acides humiques de 0.1 et 10 mg/L, tandis que le phnanthrne tait ajout via l'heptamethylnonane (HMN), un liquide non aqueux, ce qui au pralable avait produit le plus haut flux constant de phnanthrne aux cellules. De plus, nous avons utilis des tests en phase gazeuse avec des concentrations d'acides humiques de 0.1, 10 et 1000 mg/L mais avec du naphtalne. Contrairement ce que dcrit la littrature, nos rsultats ont indiqu que dans ces conditions l'expression de GFP en fonction de l'exposition au phnanthrne dans des cultures en croissance de la souche RP037 n'tait pas modifie par la prsence d'acides humiques. D'un autre ct, le test en phase gazeuse avec du naphtalne a montr que 1000 mg/L d'acides humiques abaissent lgrement mais significativement la production de GFP dans les cellules de RP037. Nous avons conclu qu'il n'y a pas d'effet gnral des acides humiques sur la disponibilit des HAP pour les bactries. Par la suite, nous nous sommes demand si des biosurfactants modifieraient la disponibilit du phnanthrne pour les bactries. Les surfactants sont souvent dcrits dans la littrature comme des moyens d'accrotre la biodisponibilit des COHs. Les surfactants sont des agents tensio-actifs qui augmentent la solubilit apparente de COH en les dissolvant l'intrieur de micelles. Nous avons ainsi test si des biosurfactants (des surfactants produits par des organismes vivants) peuvent tre utilis pour augmenter la biodisponibilit du phnanthrne pour la souche B. sartisoli RP037. Premirement, nous avons tent d'obtenir des biosurfactants produits par une autre bactrie vivant en co-culture avec les biocapteurs bactriens. Deuximement, nous avons utilis des biosurfactants purifis. La co-cultivation en prsence de la bactrie productrice de lipopeptide Pseudomonas putida souche PCL1445 a augment l'expression de GFP induite par le phnanthrne chez B. sartisoli en comparaison des cultures simples, mais cet effet n'tait pas significativement diffrent lorsque la souche RP037 tait co-cultive avec un mutant de P. putida ne produisant pas de lipopeptides. L'ajout de lipopeptides partiellement purifis dans la culture de RP037 a rsult en une rduction de la tension de surface, mais n'a pas provoqu de changement dans l'expression de GFP. D'un autre ct, l'ajout d'une solution commerciale de rhamnolipides (un autre type de biosurfactants produits par Pseudomonas spp.) a facilit la dgradation du phnanthrne par la souche RP037 et induit une expression de GFP leve dans une plus grande proportion de cellules. Nous avons ainsi conclu que les effets des biosurfactants sont mesurables l'aide de la souche biocapteur, mais que ceux-ci sont dpendants du type de surfactant utilis conjointement avec le phnanthrne. La question suivante que nous avons aborde tait si les tests utilisant des biocapteurs peuvent tre amliors de manire ce que les flux de HAP provenant de matriel contamin soient dtects. Les tests en milieu liquide avec des chantillons de sol ne fournissant pas de mesures, et sachant que les concentrations de HAP dans l'eau sont en gnral extrmement basses, nous avons conu des tests de diffusion dans lesquels nous pouvons tudier l'induction par les HAPs en fonction de la distance aux cellules. Le biocapteur bactrien B. sartisoli souche RP037 a t marqu avec une seconde protine fluorescente (mCherry), qui est constitutivement exprime dans les cellules et leur confre une fluorescence rouge/rose. La souche rsultante RP037-mChe tmoigne d'une fluorescence rouge constitutive mais n'induit la fluorescence verte qu'en prsence de naphtalne ou de phnanthrne. La prsence d'un marqueur fluorescent constitutif nous permet de visualiser les biocapteurs bactriens plus facilement parmi des particules de sol. Un test de diffusion a t conu en prparant un gel fait d'une suspension de cellules mlanges 0.5 % d'agarose. Des bandes de gel de dimensions 0.5 x 2 cm x 1 mm ont t montes dans des chambres d'incubation et exposes des sources de HAP (soit dissouts dans du HMN ou en tant que matriel solide, puis appliqus une extrmit de la bande). En utilisant ce montage exprimental, le naphtalne ou le phnanthrne (dissouts dans du HMN une concentration de 2.5 g/l) ont induit un gradient d'intensit de fluorescence GFP aprs 24 heures d'incubation, tandis que la fluorescence mCherry demeurait comparable. Un sol contamin par des HAPs (provenant d'un ancien site de production de gaz) a induit la production de GFP un niveau comparable celui du naphtalne. Des biocapteurs bactriens individuels ont galement dtect un flux de phnanthrne dans un gel contenant des particules de sol amendes avec 1 et 10 mg/g de phnanthrne. Ceci a montr que le test de diffusion peut tre utilis pour mesurer des flux de HAP provenant de matriel contamin. D'un autre ct, la sensibilit est encore trs basse pour plusieurs sols contamins, et l'autofluorescence de certains chantillons rend difficile l'identification de la rponse de la GFP chez les cellules. Pour terminer, un des points majeurs de ce travail a t la production et la validation d'une plateforme multi-puits de biocapteurs bactriens, qui a permis l'emploi simultan de plusieurs souches diffrentes de biocapteurs pour la dtection des constituants principaux du ptrole. Pour cela nous avons choisi les alcanes linaires, les composs mono-aromatiques, les biphnyls et les composs poly-aromatiques. De plus, nous avons utilis un capteur pour la gnotoxicit afin de dtecter la `toxicit globale' dans des chantillons aqueux. Plusieurs efforts d'ingnierie ont t investis de manire complter ce set. En premier lieu, chaque souche a t quipe avec soit gfp, soit luxAB en tant que signal rapporteur. Deuximement, puisqu'aucune souche de biocapteur n'tait disponible pour les HAP ou pour les alcanes longues chanes, nous avons spcifiquement construit deux nouveaux biocapteurs. L'un d'eux est galement bas sur B. sartisoli RP007, que nous avons quip avec le plasmide pPROBE-phn-luxAB pour la dtection du naphtalne et du phnanthrne mais avec production de lucifrase bactrienne. Un autre est un nouveau biocapteur bactrien pour les alcanes. Bien que nous possdions une souche Escherichia coli DHS α (pGEc74, pJAMA7) dtectant les alcanes courts de manire satisfaisante, la prsence des alcanes longues chanes n'tait pas rapporte efficacement. Nous avons clon le gne de l'activateur transcriptionnel A1kS ainsi que la rgion oprateur/promoteur de l'opron alkSB1GHJ chez la bactrie dgradant les alcanes Alcanivorax borkumensis souche SK2, afin de construire un nouveau biocapteur bactrien bnficiant d'une sensibilit accrue envers les alcanes longues chanes. Cependant, la souche rsultante E. coli DHSα (pAlk3} n'a pas montr d'mission de lumire augmente en prsence de ttradcane (C14), tandis qu'elle rapportait toujours efficacement de basses concentrations d'octane (C8). De manire surprenante, l'utilisation de A. borkumensis en tant que souche hte pour le nouveau plasmide rapporteur bas sur la GFP a totalement supprim la sensibilit pour l'octane, tandis que la dtection de ttradcane n'tait pas accrue. Cet aspect devra tre rsolu dans de futurs travaux. Pour calibrer la plateforme de biocapteurs, nous avons simul une fuite de ptrole en mer dans une bouteille en verre ouverte de 5L contenant 2L d'eau de mer contamine avec 20 ml (1%) de ptrole brut. La phase aqueuse a t chantillone intervalles rguliers aprs la fuite durant une priode allant jusqu' une semaine tandis que les principaux contaminants ptroliers taient mesurs via les biocapteurs. L'mission de bioluminescence a t mesure de manire dterminer la rponse des biocapteurs et une calibration intgre faite avec des inducteurs types a servi calculer des concentrations d'quivalents inducteurs dans l'chantillon. E. coli a t utilise en tant que souche hte pour la plupart des spcificits des biocapteurs, l'exception de la dtection du naphtalne et du phnanthrne pour lesquels nous avons utilis B. sartisoli. Cette souche, cependant, peut tre employe plus ou moins selon la mme procdure. Il est intressant de noter que le ptrole rpandu a produit une apparition squentielle de composs dissouts dans la phase aqueuse, ceux-ci .tant dtectables par les biocapteurs. Ce profil contenait d'abord les alcanes courtes chanes et les BTEX (c'est- dire benzne, tolune, thylbenzne et xylnes), apparaissant entre des minutes et des heures aprs que le ptrole a t vers. Leurs concentrations aqueuses ont par la suite fortement dcru dans l'eau chantillonne aprs 24 heures, cause de la volatilisation ou de la biodgradation. Aprs quelques jours d'incubation, ces composs sont devenus indtectables. Les HAPs, en revanche, sont apparus plus tard que les alcanes et les BTEX, et leur concentration a augment de pair avec un temps d'incubation prolong. Aucun signal significatif n'a t mis en vidence avec le biocapteur pour le biphnyl ou pour la gnotoxicit. Ceci dmontre l'utilit de ces biocapteurs, spcifiquement pour la dtection des composs ptroliers, comprenant les alcanes courtes chanes, les BTEX et les HAPs lgers.
Resumo:
Albitization is a common process during which hydrothermal fluids convert plagioclase and/or K-feldspar into nearly pure albite; however, its specific mechanism in granitoids is not well understood. The c. 1700 Ma A-type metaluminous ferroan granites in the Khetri complex of Rajasthan, NW India, have been albitized to a large extent by two metasomatic fronts, an initial transformation of oligoclase to nearly pure albite and a subsequent replacement of microcline by albite, with sharp contacts between the microcline-bearing and microcline-free zones. Albitization has bleached the original pinkish grey granite and turned it white. The mineralogical changes include transformation of oligoclase (similar to An(12)) and microcline (similar to Or(95)) to almost pure albite (similar to An(0 center dot 5-2)), amphibole from potassian ferropargasite (X-Fe 0 center dot 84-0 center dot 86) to potassic hastingsite (X-Fe 0 center dot 88-0 center dot 97) and actinolite (X-Fe 0 center dot 32-0 center dot 67), and biotite from annite (X-Fe 0 center dot 71-0 center dot 74) to annite (X-Fe 0 center dot 90-0 center dot 91). Whole-rock isocon diagrams show that, during albitization, the granites experienced major hydration, slight gain in Si and major gain in Na, whereas K, Mg, Fe and Ca were lost along with Rb, Ba, Sr, Zn, light rare earth elements and U. Whole-rock Sm-Nd isotope data plot on an apparent isochron of 1419 +/- 98 Ma and reveal significant disturbance and at least partial resetting of the intrusion age. Severe scatter in the whole-rock Rb-Sr isochron plot reflects the extreme Rb loss in the completely albitized samples, effectively freezing Sr-87/Sr-86 ratios in the albite granites at very high values (0 center dot 725-0 center dot 735). This indicates either infiltration of highly radiogenic Sr from the country rock or, more likely, radiogenic ingrowth during a considerable time lag (estimated to be at least 300 Myr) between original intrusion and albitization. The albitization took place at similar to 350-400 degrees C. It was caused by the infiltration of an ascending hydrothermal fluid that had acquired high Na/K and Na/Ca ratios during migration through metamorphic rocks at even lower temperatures in the periphery of the plutons. Oxygen isotope ratios increase from delta O-18 = 7 parts per thousand in the original granite to values of 9-10 parts per thousand in completely albitized samples, suggesting that the fluid had equilibrated with surrounding metamorphosed crust. A metasomatic model, using chromatographic theory of fluid infiltration, explains the process for generating the observed zonation in terms of a leading metasomatic front where oligoclase of the original granite is converted to albite, and a second, trailing front where microcline is also converted to albite. The temperature gradients driving the fluid infiltration may have been produced by the high heat production of the granites themselves. The confinement of the albitized granites along the NE-SW-trending Khetri lineament and the pervasive nature of the albitization suggest that the albitizing fluids possibly originated during reactivation of the lineament. More generally, steady-state temperature gradients induced by the high internal heat production of A-type granites may provide the driving force for similar metasomatic and ore-forming processes in other highly enriched granitoid bodies.
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The present study is an analysis of IR sources in the Alpha Persei open cluster region from the IRAS Point Source Catalog and from ground-based photometric observations. Cross-identification between stars in the region and IRAS Point Source Catalog was performed and nine new associations were found. BVRI Johnson photometry for 24 of the matched objects have been carried out. Physical identity of visual and IRAS sources and relationship to the Alpha Persei open cluster are discussed.
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Intensification of agricultural production without a sound management and regulations can lead to severe environmental problems, as in Western Santa Catarina State, Brazil, where intensive swine production has caused large accumulations of manure and consequently water pollution. Natural resource scientists are asked by decision-makers for advice on management and regulatory decisions. Distributed environmental models are useful tools, since they can be used to explore consequences of various management practices. However, in many areas of the world, quantitative data for model calibration and validation are lacking. The data-intensive distributed environmental model AgNPS was applied in a data-poor environment, the upper catchment (2,520 ha) of the Ariranhazinho River, near the city of Seara, in Santa Catarina State. Steps included data preparation, cell size selection, sensitivity analysis, model calibration and application to different management scenarios. The model was calibrated based on a best guess for model parameters and on a pragmatic sensitivity analysis. The parameters were adjusted to match model outputs (runoff volume, peak runoff rate and sediment concentration) closely with the sparse observed data. A modelling grid cell resolution of 150 m adduced appropriate and computer-fit results. The rainfall runoff response of the AgNPS model was calibrated using three separate rainfall ranges (< 25, 25-60, > 60 mm). Predicted sediment concentrations were consistently six to ten times higher than observed, probably due to sediment trapping along vegetated channel banks. Predicted N and P concentrations in stream water ranged from just below to well above regulatory norms. Expert knowledge of the area, in addition to experience reported in the literature, was able to compensate in part for limited calibration data. Several scenarios (actual, recommended and excessive manure applications, and point source pollution from swine operations) could be compared by the model, using a relative ranking rather than quantitative predictions.
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Soil infiltration is a key link of the natural water cycle process. Studies on soil permeability are conducive for water resources assessment and estimation, runoff regulation and management, soil erosion modeling, nonpoint and point source pollution of farmland, among other aspects. The unequal influence of rainfall duration, rainfall intensity, antecedent soil moisture, vegetation cover, vegetation type, and slope gradient on soil cumulative infiltration was studied under simulated rainfall and different underlying surfaces. We established a six factor-model of soil cumulative infiltration by the improved back propagation (BP)-based artificial neural network algorithm with a momentum term and self-adjusting learning rate. Compared to the multiple nonlinear regression method, the stability and accuracy of the improved BP algorithm was better. Based on the improved BP model, the sensitive index of these six factors on soil cumulative infiltration was investigated. Secondly, the grey relational analysis method was used to individually study grey correlations among these six factors and soil cumulative infiltration. The results of the two methods were very similar. Rainfall duration was the most influential factor, followed by vegetation cover, vegetation type, rainfall intensity and antecedent soil moisture. The effect of slope gradient on soil cumulative infiltration was not significant.
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The North Fork Maquoketa River Headwaters (NFMRH) has been identified as impaired by nutrients, episodic slugs of ammonia and sediment. The NFMRH TMDL plan calls for a "phasing approach" to managing water quality when the origin is non-point source contaminants. This project will address phase 1 using a performance reward program for targeted cooperators to improve environmental index scores using cost-share, EQIP practices and flexible management alternatives. Pre-project assessments suggest that rewards should target refined management of erosion-prone fields and farms with livestock populations, which contribute to the P and N loads responsible for fertilizing filamentous algae blooms that depress dissolved oxygen concentrations in the NFMRH. The Phosphorus Index, Soil Conditioning Index and cornstalk nitrate test will be used by producers to determine effective alternatives, such as no-till planting, to reduce nutrient and sediment delivery. These evironmental indexes will be especially useful for livestock producers in the livestock dense watershed. This project will extend a NRCS-sponsored Conservation Innovation Grant currently offered to producers in the Coffee Creek sub-watershed to a three-year, watershed-wide effort that will be necessary to make significant improvements in environmental management.
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This project brings together rural and urban partners to address the impairment of Miners Creek, a cold water trout stream in Northeast Iowa. It eliminates point source pollution contributions from the City of Guttenberg, decreases non-point source pollution and increases in-stream and near stream habitat in the Miners Creek Watershed. It specifically eliminates sewage and storm water runoff from the City of Guttenberg into Miners Creek; it develops, enhances and preserves wetlands; reduces direct livestock access to the. stream through rotational grazing systems; completes stream bank stabilizatio11 and in-stream habitat creation; targets upland land treatment; and promotes targeted application of continuous CRP and forestry practices. This project recognizes that non-point source pollution improvements could be hampered by point source pollutants ihat inhibit biologic reproduction and survival. It takes appropliate measures to improve all aspects of the stream ecosystem.
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Objective: To describe an ongoing outbreak that tripled the annual detection of methicillin-resistant Staphylococcus aureus (MRSA) carriage in a tertiary care hospital. Methods: Active surveillance of MRSA is performed since 20 years in our hospital. Our protocol includes screening of patients transferred from high-incidence health-care institutions or countries, roommates of new MRSA cases, and wards where _2 patients acquired MRSA during the same week. Contact precautions are used for known carriers. PFGE was used for molecular typing until 2004, and was then replaced by Double-Locus Sequence Typing (DLST). Results: A median yearly incidence of 173 new carriers of MRSA was observed from 2002 to 2007. Since September 2008, an increasing number of new cases were observed, mainly as successive clusters limited to distinct wards, reaching a total of 398 until October 2009. The yearly incidence of new cases rose to 275 in 2008 and 613 in 2009. 60% of the cases were due to one strain: DLST 4−4, ST 228, SCCmecI. The incidence of new cases due to the previously predominant strains remained unchanged. The epidemic strain corresponded to a new variant of a clone responsible for a previous outbreak in 2001, and only sporadically isolated (mean of 20 cases/year) since then. A case- control study documented a significant association between acquisition of the epidemic strain and a stay in intensive and intermediary care units, a highest number of internal transfers, but did not identify a point source of transmission. Infection control practices and antibiotic policy had remained unchanged for several years. Compliance with handhygiene as monitored yearly was on the rise. Screening of 313 healthcare workers only found one carrier of the epidemic strain lately in the outbreak. Additional infection control measures were enforced, including screening at ICU admission and discharge with PCR-based rapid test, routine screening for all patients leaving epidemic wards, introduction of PCR-based rapid test for contact tracing, additional working forces for environmental disinfection, and hospital-wide education of healthcare workers. However, the outbreak was still ongoing after 5 months. Conclusions: Factors linked to the dissemination of this new variant in our institution remain undetermined. This unresolved outbreak suggests that this new variant acquired hyperepidemic properties, which calls for further investigations.
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The purpose of this study was to assess the spatial resolution of a computed tomography (CT) scanner with an automatic approach developed for routine quality controls when varying CT parameters. The methods available to assess the modulation transfer functions (MTF) with the automatic approach were Droege's and the bead point source (BPS) methods. These MTFs were compared with presampled ones obtained using Boone's method. The results show that Droege's method is not accurate in the low-frequency range, whereas the BPS method is highly sensitive to image noise. While both methods are well adapted to routine stability controls, it was shown that they are not able to provide absolute measurements. On the other hand, Boone's method, which is robust with respect to aliasing, more resilient to noise and provides absolute measurements, satisfies the commissioning requirements perfectly. Thus, Boone's method combined with a modified Catphan 600 phantom could be a good solution to assess CT spatial resolution in the different CT planes.
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When decommissioning a nuclear facility it is important to be able to estimate activity levels of potentially radioactive samples and compare with clearance values defined by regulatory authorities. This paper presents a method of calibrating a clearance box monitor based on practical experimental measurements and Monte Carlo simulations. Adjusting the simulation for experimental data obtained using a simple point source permits the computation of absolute calibration factors for more complex geometries with an accuracy of a bit more than 20%. The uncertainty of the calibration factor can be improved to about 10% when the simulation is used relatively, in direct comparison with a measurement performed in the same geometry but with another nuclide. The simulation can also be used to validate the experimental calibration procedure when the sample is supposed to be homogeneous but the calibration factor is derived from a plate phantom. For more realistic geometries, like a small gravel dumpster, Monte Carlo simulation shows that the calibration factor obtained with a larger homogeneous phantom is correct within about 20%, if sample density is taken as the influencing parameter. Finally, simulation can be used to estimate the effect of a contamination hotspot. The research supporting this paper shows that activity could be largely underestimated in the event of a centrally-located hotspot and overestimated for a peripherally-located hotspot if the sample is assumed to be homogeneously contaminated. This demonstrates the usefulness of being able to complement experimental methods with Monte Carlo simulations in order to estimate calibration factors that cannot be directly measured because of a lack of available material or specific geometries.
Resumo:
The following document serves two purposes. First, the Environmental Protection Agency (EPA) requires a state to develop an approved Non-point Source Management Plan (NPSMP or Plan) that encompasses the nine key elements, described in full in Appendix A, to be eligible for federal Clean Water Act Section 319 funding. Second, the Plan serves as a representation of Iowas vision, goals, objectives and potential action steps to reduce non-point source pollution and improve water quality over the next five to ten years. This plan is not intended to be, nor should it be, limited to the Department of Natural Resources or Iowas Section 319 Program, but rather reflects the collective efforts and intents of the core partners and stakeholder groups that worked together to develop the goals identified herein and programmatic means of achieving those goals.
Resumo:
Part of a phased approach, an intensive information and education program, construction of erosion control practices, and sediment control on construction sites is proposed. These proposed practices will manage sediment runoff and nutrient runoff on agricultural and urban areas. Sediment control structures such as waterways, wetlands, modified terraces, grade stabilization structures, sediment basins, and rain gardens is proposed and will be combined with nutrient and pesticide management and reduced tillage to reduce non-point source pollution. A reduction of 15% of the sediment and phosphorus delivered to a water body from priority areas will be looked at as a success in this short-term project focused primarily at education within the project area which is also, for the most part, the top 25% sediment load producing sub-watersheds. In addition, four urban areas have been identified as part of this project as needing immediate assistance. A combination of urban and agricultural conservation practices, shoreline revegetation, and education of landowners will be used to achieve these results on both the urban and the agricultural arena.
Resumo:
The goal of this project is to help residents of the Hewitt Creek watershed identify themselves as a watershed community and use cost-effective approaches to control non-point source nutrient and sediment contaminants according to collective science-based environmental goals. The project will tap the low-cost, high-return human resources of local knowledge and resident leadership for economical and sustainable solutions. A watershed council will implement an incentive program to engage their watershed community in locally-acceptable practices and performance (outcome) measures for environmental stewardship that have reasonable cost and are linked with accountable crop and livestock management decisions. The Iowa and Dubuque County Farm Bureau have supported one year of management practice incentives. The performance incentive program will take this effort to the next level, to focus on outcomes.
