Effect of isobutanol on toluene biodegradation in nitrate amended, sulfate amended and methanogenic enrichment microcosms.

PubMed

Jayamani, Indumathy; Cupples, Alison M

2013-09-01

Isobutanol is an alternate fuel additive that is being considered because of economic and lower emission benefits. However, future gasoline spills could result in co-contamination of isobutanol with gasoline components such as benzene, toluene, ethyl-benzene and xylene. Hence, isobutanol could affect the degradability of gasoline components thereby having an effect on contaminant plume length and half-life. In this study, the effect of isobutanol on the biodegradation of a model gasoline component (toluene) was examined in laboratory microcosms. For this, toluene and isobutanol were added to six different toluene degrading laboratory microcosms under sulfate amended, nitrate amended or methanogenic conditions. While toluene biodegradation was not greatly affected in the presence of isobutanol in five out of the six different experimental sets, toluene degradation was completely inhibited in one set of microcosms. This inhibition occurred in sulfate amended microcosms constructed with inocula from wastewater treatment plant activated sludge. Our data suggest that toluene degrading consortia are affected differently by isobutanol addition. These results indicate that, if co-contamination occurs, in some cases the in situ half-life of toluene could be significantly extended.

The University as Microcosm

ERIC Educational Resources Information Center

Kaldis, Byron

2009-01-01

This paper puts forward the model of "microcosm-macrocosm" isomorphism encapsulated in certain philosophical views on the form of university education. The human being as a "microcosm" should reflect internally the external "macrocosm". Higher Education is a socially instituted attempt to guide human beings into forming themselves as microcosms of…

Evidence of polycyclic aromatic hydrocarbon biodegradation in a contaminated aquifer by combined application of in situ and laboratory microcosms using (13)C-labelled target compounds.

PubMed

Bahr, Arne; Fischer, Anko; Vogt, Carsten; Bombach, Petra

2015-02-01

The number of approaches to evaluate the biodegradation of polycyclic aromatic hydrocarbons (PAHs) within contaminated aquifers is limited. Here, we demonstrate the applicability of a novel method based on the combination of in situ and laboratory microcosms using (13)C-labelled PAHs as tracer compounds. The biodegradation of four PAHs (naphthalene, fluorene, phenanthrene, and acenaphthene) was investigated in an oxic aquifer at the site of a former gas plant. In situ biodegradation of naphthalene and fluorene was demonstrated using in situ microcosms (BACTRAP(®)s). BACTRAP(®)s amended with either [(13)C6]-naphthalene or [(13)C5/(13)C6]-fluorene (50:50) were incubated for a period of over two months in two groundwater wells located at the contaminant source and plume fringe, respectively. Amino acids extracted from BACTRAP(®)-grown cells showed significant (13)C-enrichments with (13)C-fractions of up to 30.4% for naphthalene and 3.8% for fluorene, thus providing evidence for the in situ biodegradation and assimilation of those PAHs at the field site. To quantify the mineralisation of PAHs, laboratory microcosms were set up with BACTRAP(®)-grown cells and groundwater. Naphthalene, fluorene, phenanthrene, or acenaphthene were added as (13)C-labelled substrates. (13)C-enrichment of the produced CO2 revealed mineralisation of between 5.9% and 19.7% for fluorene, between 11.1% and 35.1% for acenaphthene, between 14.2% and 33.1% for phenanthrene, and up to 37.0% for naphthalene over a period of 62 days. Observed PAH mineralisation rates ranged between 17 μg L(-1) d(-1) and 1639 μg L(-1) d(-1). The novel approach combining in situ and laboratory microcosms allowed a comprehensive evaluation of PAH biodegradation at the investigated field site, revealing the method's potential for the assessment of PAH degradation within contaminated aquifers. Copyright © 2014 Elsevier Ltd. All rights reserved.

AEROBIC SOIL MICROCOSMS FOR LONG-TERM BIODEGRADATION OF HYDROCARBON VAPORS

EPA Science Inventory

The aims of this research project included the development of laboratory protocols for the preparation of aerobic soil microcosms using aseptic field soil samples, and for the gas chromatographic analysis of hydrocarbon vapor biodegradation based on vapor samples obtained from th...

A simple, inexpensive, and field-relevant microcosm tidal simulator for use in marsh macrophyte studies1

PubMed Central

MacTavish, Rachel M.; Cohen, Risa A.

2014-01-01

• Premise of the study: A microcosm unit with tidal simulation was developed to address the challenge of maintaining ecologically relevant tidal regimes while performing controlled greenhouse experiments on smooth cordgrass, Spartina alterniflora. • Methods and Results: We designed a simple, inexpensive, easily replicated microcosm unit with tidal simulation and tested whether S. alterniflora growth in microcosms with tidal simulation was similar to that of tidally influenced plants in the field on Sapelo Island, Georgia. After three months of exposure to either natural or simulated tidal treatment, plants in microcosms receiving tidal simulation had similar stem density, height, and above- and belowground biomass to plants in field plots. • Conclusions: The tidal simulator developed may provide an inexpensive, effective method for conducting studies on S. alterniflora and other tidally influenced plants in controlled settings to be used not only to complement field studies, but also in locations without coastal access. PMID:25383265

A Reproducible Oral Microcosm Biofilm Model for Testing Dental Materials

PubMed Central

Rudney, J.D.; Chen, R.; Lenton, P.; Li, J.; Li, Y.; Jones, R.S.; Reilly, C.; Fok, A.S.; Aparicio, C.

2012-01-01

Aims Most studies of biofilm effects on dental materials use single-species biofilms, or consortia. Microcosm biofilms grown directly from saliva or plaque are much more diverse, but difficult to characterize. We used the Human Oral Microbial Identification Microarray (HOMIM) to validate a reproducible oral microcosm model. Methods and Results Saliva and dental plaque were collected from adults and children. Hydroxyapatite and dental composite disks were inoculated with either saliva or plaque, and microcosm biofilms were grown in a CDC biofilm reactor. In later experiments, the reactor was pulsed with sucrose. DNA from inoculums and microcosms were analyzed by HOMIM for 272 species. Microcosms included about 60% of species from the original inoculum. Biofilms grown on hydroxyapatite and composites were extremely similar. Sucrose-pulsing decreased diversity and pH, but increased the abundance of Streptococcus and Veilonella. Biofilms from the same donor, grown at different times, clustered together. Conclusions This model produced reproducible microcosm biofilms that were representative of the oral microbiota. Sucrose induced changes associated with dental caries. Significance and Impact of the Study This is the first use of HOMIM to validate an oral microcosm model that can be used to study the effects of complex biofilms on dental materials. PMID:22925110

Biomineralization of 1,4-dioxane in Pure Culture, Microcosm, and Column Studies Using 13C Labeling

NASA Astrophysics Data System (ADS)

Rolston, H. M.; Azizian, M.; Hyman, M. R.; Semprini, L.

2016-12-01

1,4-dioxane (1,4-D), a probable human carcinogen at low (< 1ppb) concentrations, is a widely occurring groundwater contaminant due to its use as a stabilizer for chlorinated solvents. Aerobic cometabolism, the use of a primary substrate to induce the production of microbial enzymes capable of transforming contaminants into innocuous products, is a promising in-situ treatment strategy for 1,4-D because it has the potential to mineralize trace 1,4-D concentrations to carbon dioxide (CO2). Previous work has confirmed the bacterium Rhodococcus rhodochrous (strain ATCC 21198) will transform 1,4-D when grown on isobutane. In this study, 13C uniformly labeled 1,4-D was used to determine the extent to which strain ATCC 21198 biomineralizes 1,4-D to CO2. Batch experiments have been conducted with pure culture 21198 and in microcosms constructed with aquifer sediments. The rate of resting cell transformation of 1,4-D by ATCC 21198 was over 100 times faster than the rate of CO2 accumulation, indicating the presence of intermediates that were slowly mineralized to CO2 . In microcosms, the use of isobutane as a primary substrate effectively stimulated the native microbial community to transform 1,4-D. Microcosms were also bioaugmented with ATCC 21198. After an initial lag and subsequent additions of isobutane, transformation rates in the native microcosms approached those of the bioaugmented microcosms. Cometabolically active microbes survived several periods of starvation in all microcosms, and nutrient amendment allowed for sustained transformation rates. 13C labeled 1,4-D is currently being used to determine the rates and extents of biomineralization in the microcosms. Column studies are also being conducted to evaluate cometabolism and biominerazation potential of isobutane as a biostimulant and 21198 for bioaugmentation under geochemical and flow conditions more representative of in-situ bioremediation.

Effects of sediment-spiked lufenuron on benthic macroinvertebrates in outdoor microcosms and single-species toxicity tests.

PubMed

Brock, T C M; Bas, D A; Belgers, J D M; Bibbe, L; Boerwinkel, M-C; Crum, S J H; Diepens, N J; Kraak, M H S; Vonk, J A; Roessink, I

2016-08-01

Sediment ecotoxicity studies were conducted with lufenuron to (i) complement the results of a water-spiked mesocosm experiment with this lipophilic benzoylurea insecticide, (ii) to explore the predictive value of laboratory single-species tests for population and community-level responses of benthic macroinvertebrates, and (iii) to calibrate the tier-1 effect assessment procedure for sediment organisms. For this purpose the concentration-response relationships for macroinvertebrates between sediment-spiked microcosms and those of 28-d sediment-spiked single-species toxicity tests with Chironomus riparius, Hyalella azteca and Lumbriculus variegatus were compared. Lufenuron persisted in the sediment of the microcosms. On average, 87.7% of the initial lufenuron concentration could still be detected in the sediment after 12 weeks. Overall, benthic insects and crustaceans showed treatment-related declines and oligochaetes treatment-related increases. The lowest population-level NOEC in the microcosms was 0.79μg lufenuron/g organic carbon in dry sediment (μg a.s./g OC) for Tanytarsini, Chironomini and Dero sp. Multivariate analysis of the responses of benthic macroinvertebrates revealed a community-level NOEC of 0.79μg a.s./g OC. The treatment-related responses observed in the microcosms are in accordance with the results of the 28-d laboratory toxicity tests. These tests showed that the insect C. riparius and the crustacean H. azteca were approximately two orders of magnitude more sensitive than the oligochaete L. variegatus. In our laboratory tests, using field-collected sediment, the lowest 28-d EC10 (0.49μg a.s./g OC) was observed for C. riparius (endpoint survival), while for the standard OECD test with this species, using artificial sediment, a NOEC of 2.35μg a.s./g OC (endpoint emergence) is reported. In this particular case, the sediment tier-1 effect assessment using the chronic EC10 (field-collected sediment) or chronic NOEC (artificial sediment) of C

Evaluation of aquatic sediment microcosms and their use in assessing possible effects of introduced microorganisms on ecosystem parameters.

PubMed Central

Wagner-Döbler, I; Pipke, R; Timmis, K N; Dwyer, D F

1992-01-01

In this paper we describe a sediment microcosm system consisting of 20 undisturbed, layered sediment cores with overlying site water which are incubated under identical conditions of temperature, light, stirring rate of overlying water, and water exchange rate. Ecosystem parameters (nutrient level, photosynthetic potential, community structure of heterotrophic bacteria, thymidine incorporation rate, and oxygen microgradients) of the laboratory microcosms and the source ecosystem were compared and shown to be indistinguishable for the first 2 weeks. In weeks 3 and 4, small differences were detectable in the nutrient level, community structure of heterotrophic bacteria, and thymidine incorporation rate. However, the photosynthetic potential, depth profiles of heterotrophic bacterial community structure, and oxygen microgradients were maintained throughout the incubation period and did not differ between laboratory microcosms and the source ecosystem. The microcosm system described here would thus appear to be a valid model of aquatic sediments for up to 4 weeks; the actual period would depend on the sediment source and incubation temperature. The validated systems were used with Rhine river sediment to assess possible effects on ecosystem parameters of Pseudomonas sp. strain B13 FR1(pFRC20P), a genetically engineered microorganism (GEM) that had been constructed to degrade mixtures of halo- and alkylbenzoates and -phenols. The GEM survived in the surface sediment at densities of 5 x 10(4) to 5 x 10(5)/g (dry weight) for 4 weeks and degraded added chloro- and methylaromatics. The GEM did not measurably influence ecosystem parameters such as photosynthesis, densities of selected heterotrophic bacteria, thymidine incorporation rate, and oxygen microgradients. Thus, the microcosm system described here would seem to be useful for the study of the ecology of biodegradation and the fate and effect of microorganisms introduced into the environment. PMID:1599244

Use of statistical tools to evaluate the reductive dechlorination of high levels of TCE in microcosm studies.

PubMed

Harkness, Mark; Fisher, Angela; Lee, Michael D; Mack, E Erin; Payne, Jo Ann; Dworatzek, Sandra; Roberts, Jeff; Acheson, Carolyn; Herrmann, Ronald; Possolo, Antonio

2012-04-01

A large, multi-laboratory microcosm study was performed to select amendments for supporting reductive dechlorination of high levels of trichloroethylene (TCE) found at an industrial site in the United Kingdom (UK) containing dense non-aqueous phase liquid (DNAPL) TCE. The study was designed as a fractional factorial experiment involving 177 bottles distributed between four industrial laboratories and was used to assess the impact of six electron donors, bioaugmentation, addition of supplemental nutrients, and two TCE levels (0.57 and 1.90 mM or 75 and 250 mg/L in the aqueous phase) on TCE dechlorination. Performance was assessed based on the concentration changes of TCE and reductive dechlorination degradation products. The chemical data was evaluated using analysis of variance (ANOVA) and survival analysis techniques to determine both main effects and important interactions for all the experimental variables during the 203-day study. The statistically based design and analysis provided powerful tools that aided decision-making for field application of this technology. The analysis showed that emulsified vegetable oil (EVO), lactate, and methanol were the most effective electron donors, promoting rapid and complete dechlorination of TCE to ethene. Bioaugmentation and nutrient addition also had a statistically significant positive impact on TCE dechlorination. In addition, the microbial community was measured using phospholipid fatty acid analysis (PLFA) for quantification of total biomass and characterization of the community structure and quantitative polymerase chain reaction (qPCR) for enumeration of Dehalococcoides organisms (Dhc) and the vinyl chloride reductase (vcrA) gene. The highest increase in levels of total biomass and Dhc was observed in the EVO microcosms, which correlated well with the dechlorination results. Copyright © 2012 Elsevier B.V. All rights reserved.

A laboratory study of the biodegradation of an alcohol ethoxylate surfactant by native soil microbes

NASA Astrophysics Data System (ADS)

Ang, Carolina C.; Abdul, Abdul S.

1992-09-01

Laboratory experiments were conducted to study the biodegradation of a nonionic alcohol ethoxylate surfactant by native microbes from a contaminated site. Three sets of experiments consisting of 13 microcosms were carried out to evaluate the rate of biodegradation and the effect of nutrients and supplementary oxygen on the degradation process. The results from these active microcosms were compared with those for controlled microcosms in which a biocide was added to inhibit biological activities. In the presence of ground water and sterilized soil, surfactant solutions with initial concentrations of 1000, 650, 250, and 180 mgl -1 were reduced to less than 5 mgl -1 in 36 days, 20 days, 17 days, and 17 days, respectively. The biodegradation rate in microcosms with added nutrients was more than twice the rate in the reactor without nutrients. The results from experiments in which various nitrogen and phosphorus nutrients were added showed that a ratio of 10 carbon:2 nitrogen:1 phosphorus was the optimum for the biodegradation of surfactant under the microcosm conditions. The addition of 5 mgl -1 of oxygen in the form of hydrogen peroxide increased the degradation rate of surfactant by 30%. The study showed that microbes indigenous to the soil and ground water at a contaminated site rapidly degrade the low levels of the surfactant that may remain at the site after soil washing, and that the degradation rate can be increased by the addition of nutrients and oxygen.

Individual and combined effects of cadmium and diesel on a nematode community in a laboratory microcosm experiment.

PubMed

Beyrem, H; Mahmoudi, E; Essid, N; Hedfi, A; Boufahja, F; Aïssa, P

2007-11-01

A microcosm experiment was carried out to study the influence of cadmium and diesel, individually and in a mixture, on a free living nematode community of a Tunisian lagoon. Sediments were contaminated with cadmium that ranged in concentration from 0.54 to 1.40 mg Cd kg(-1) (dry weight (dw)), by diesel at 0.25 mg kg(-1) (dw), by a cadmium-diesel mixture (Cd at 1.40 mg kg(-1)+Diesel at 0.25 mg kg(-1)) and effects were examined after 90 days. Univariate analysis showed that all univariate indices did not change significantly neither at all the levels of cadmium contamination nor at 0.25 mg kg(-1) (dw) diesel concentration. But, at the cadmium-diesel mixture, significant differences were recorded between nematode assemblages from uncontaminated sediment control microcosm and those from cadmium-diesel mixture amended sediment treatments. Total nematode abundance (I), mean individual weight (bi), Shannon-Weaver index H', species richness (d), evenness (J') and number of species (S) decreased significantly in microcosms contaminated with both cadmium and diesel. Results from multivariate analyses of the species abundance data demonstrated that responses of nematode species to the cadmium-diesel treatments were varied: Marylynnia stekhoveni, Calomicrolaimus honestus and Oncholaimellus mediterraneus were significantly affected at the cadmium-diesel contamination but they were not eliminated. These species could be categorized as "cadmium-diesel sensitive". Enoploides sp. and Oncholaimus campylocercoides, characterized by increased abundances in cadmium-diesel amended sediment, seemed to be "cadmium-diesel resistant" species. All these species, "cadmium-diesel sensitive" or "cadmium-diesel resistant", were not affected by either cadmium or diesel alone.

MICROCOSM AND IN-SITU FIELD STUDIES OF ENHANCED BIOTRANSFORMATION OF TRICHLOROETHYLENE BY PHENOL-UTILIZING MICROORGANISMS

EPA Science Inventory

The ability of different aerobic groundwater microorganisms to cometabolically degrade trichloroethylene (TCE), 1,2-cis-dichloroethylene (c-DCE), and 1,2-trans-dichloroethylene (t-DCE) was evaluated both in groundwater-fed microcosms and in situ in a shallow aquifer. Microcosms a...

Effect of Biochar on Greenhouse Gas Emissions and Nitrogen Cycling in Laboratory and Field Experiments

NASA Astrophysics Data System (ADS)

Hagemann, Nikolas; Harter, Johannes; Kaldamukova, Radina; Ruser, Reiner; Graeff-Hönninger, Simone; Kappler, Andreas; Behrens, Sebastian

2014-05-01

The extensive use of nitrogen (N) fertilizers in agriculture is a major source of anthropogenic N2O emissions contributing 8% to global greenhouse gas emissions. Soil biochar amendment has been suggested as a means to reduce both CO2 and non-CO2 greenhouse gas emissions. The reduction of N2O emissions by biochar has been demonstrated repeatedly in field and laboratory experiments. However, the mechanisms of the reduction remain unclear. Further it is not known how biochar field-weathering affects GHG emissions and how agro-chemicals, such as the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), that is often simultaneously applied together with commercial N-fertilizers, impact nitrogen transformation and N2O emissions from biochar amended soils. In order investigate the duration of the biochar effect on soil N2O emissions and its susceptibility to DMPP application we performed a microcosm and field study with a high-temperature (400 ° C) beech wood derived biochar (60 t ha-1 and 5 % (w/w) biochar in the field and microcosms, respectively). While the field site contained the biochar already for three years, soil and biochar were freshly mixed for the laboratory microcosm experiments. In both studies we quantified GHG emissions and soil nitrogen speciation (nitrate, nitrite, ammonium). While the field study was carried out over the whole vegetation period of the sunflower Helianthus annuus L., soil microcosm experiments were performed for up to 9 days at 28° C. In both experiments a N-fertilizer containing DMPP was applied either before planting of the sunflowers or at the beginning of soil microcosms incubation. Laboratory microcosm experiments were performed at 60% water filled pore space reflecting average field conditions. Our results show that biochar effectively reduced soil N2O emissions by up to 60 % in the field and in the soil microcosm experiments. No significant differences in N2O emission mitigation potential between field-aged and fresh

Microbial community analysis of switchgrass planted and unplanted soil microcosms displaying PCB dechlorination

PubMed Central

Liang, Yi; Meggo, Richard; Hu, Dingfei; Schnoor, Jerald L.; Mattes, Timothy E.

2015-01-01

Polychlorinated biphenyls (PCBs) pose potential risks to human and environmental health because they are carcinogenic, persistent and bioaccumulative. In this study we investigated bacterial communities in soil microcosms spiked with PCB 52, 77 and 153. Switchgrass (Panicum virgatum) was employed to improve overall PCB removal and redox cycling (i.e. sequential periods of flooding followed by periods of no flooding) was performed in an effort to promote PCB dechlorination. Lesser chlorinated PCB transformation products were detected in all microcosms, indicating the occurrence of PCB dechlorination. Terminal restriction fragment length polymorphism (T-RFLP) and clone library analysis showed that PCB spiking, switchgrass planting and redox cycling affected the microbial community structure. Putative organohalide-respiring Chloroflexi populations, which were not found in unflooded microcosms, were enriched after two weeks of flooding in the redox-cycled microcosms. Sequences classified as Geobacter sp. were detected in all microcosms, and were most abundant in the switchgrass-planted microcosm spiked with PCB congeners. The presence of possible organohalide-respiring bacteria in these soil microcosms suggests they play a role in PCB dechlorination therein. PMID:25820643

Microbial community analysis of switchgrass planted and unplanted soil microcosms displaying PCB dechlorination.

PubMed

Liang, Yi; Meggo, Richard; Hu, Dingfei; Schnoor, Jerald L; Mattes, Timothy E

2015-08-01

Polychlorinated biphenyls (PCBs) pose potential risks to human and environmental health because they are carcinogenic, persistent, and bioaccumulative. In this study, we investigated bacterial communities in soil microcosms spiked with PCB 52, 77, and 153. Switchgrass (Panicum virgatum) was employed to improve overall PCB removal, and redox cycling (i.e., sequential periods of flooding followed by periods of no flooding) was performed in an effort to promote PCB dechlorination. Lesser chlorinated PCB transformation products were detected in all microcosms, indicating the occurrence of PCB dechlorination. Terminal restriction fragment length polymorphism (T-RFLP) and clone library analysis showed that PCB spiking, switchgrass planting, and redox cycling affected the microbial community structure. Putative organohalide-respiring Chloroflexi populations, which were not found in unflooded microcosms, were enriched after 2 weeks of flooding in the redox-cycled microcosms. Sequences classified as Geobacter sp. were detected in all microcosms and were most abundant in the switchgrass-planted microcosm spiked with PCB congeners. The presence of possible organohalide-respiring bacteria in these soil microcosms suggests that they play a role in PCB dechlorination therein.

Response of the Predatory Bacterium, Halobacteriovorax, and Virus to an Influx of a Prey Bacterium in a Natural Water Microcosm and a Three Membered Artificial Sea Water Microcosm.

NASA Astrophysics Data System (ADS)

Williams, H.; Chen, H.; Laws, E. A.; Gulig, P. A.

2016-02-01

Halobacteriovorax (HBx) is a predatory bacterium that preys on Vibrio sp. and many other gram negative bacteria. There is strong evidence that suggest HBx has a role in bacterial mortality in marine and brackish systems. However, its role has not been appropriately explored. In this study the rate of HBx predation on Vibrio vulnificus in comparison to that of viruses has been investigated. Initial experiments compared the responses of HBx and viruses in estuarine water systems to an input of V. vulnificus. Environmental water samples were filtered to remove larger protists and other organisms and debris. The filtered samples were used to establish laboratory microcosms to which was added a suspension of V. vulnificus. To measure the responses of HBx and viruses to the influx of V. vulnificus, samples were removed at intervals over a 40 h incubation period to enumerate HBx and V. vulnificus by culture and viruses by direct microscopic counts. In a subsequent experiment we investigated the responses of a virus and HBx strain when cultured with a suspension of V. vulnificus in a laboratory controlled microcosm of artificial sea water. The results of both experiments revealed that HBx was the first and most rapid responder to the inoculum of V. vulnificus and reduced their numbers significantly. The viruses were relatively non-responsive and did not substantially reduce V. vulnifius numbers. These results show that HBx may be a major contributor to bacterial mortality in conjunction with protists and viruses

PERSPECTIVE ON THE ROLE OF MICROCOSMS IN ENVIRONMENTAL FATE AND EFFECTS ASSESSMENTS

EPA Science Inventory

This paper provides a perspective on the possible interfacing of microcosm studies with both waste assimilatory capacity determinations and other less quantitative types of assessment. Some of the problems and inconsistencies in the interpretation and application of microcosm res...

Factors Influencing TCE Anaerobic Dechlorination Investigated via Simulations of Microcosm Experiments

NASA Astrophysics Data System (ADS)

Mao, X.; Harkness, M.; Lee, M. D.; Mack, E. E.; Dworatzek, S.; Acheson, C.; McCarty, P.; Barry, D. A.; Gerhard, J. I.

2006-12-01

SABRE (Source Area BioREmediation) is a public-private consortium whose charter is to determine if enhanced anaerobic bioremediation can result in effective and quantifiable treatment of chlorinated solvent DNAPL source areas. The focus of this 4-year, $5.7 million research project is a field site in the United Kingdom containing a TCE DNAPL source area. In preparation, a microcosm study was performed to determine the optimal combination of factors to support reductive dechlorination of TCE in site soil and groundwater. The study consisted of 168 bottles distributed between four laboratories (Dupont, GE, SiREM, and Terra Systems) and tested the impact of six carbon substrates (lactate, acetate, methanol, SRS (soybean oil), hexanol, butyl acetate), bioaugmentation with KB-1 bacterial culture, three TCE levels (100 mg/L, 400 mg/L, and 800 mg/L) and two sulphate levels (200 mg/L, >500 mg/L) on TCE dechlorination. This research presents a numerical model designed to simulate the main processes occurring in the microcosms, including substrate fermentation, sequential dechlorination, toxic inhibition, and the influence of sulphate concentration. In calibrating the model to over 60 of the microcosm experiments, lumped parameters were employed to quantify the effect of key factors on the conversion rate of each chlorinated ethene in the TCE degradation sequence. Results quantify the benefit (i.e., increased stepwise dechlorination rate) due to both bioaugmentation and the presence of higher sulphate concentrations. Competitive inhibition is found to increase in significance as TCE concentrations increase; however, inclusion of Haldane inhibition is not supported. Over a wide range of experimental conditions and dechlorination steps, SRS appears to induce relatively little hydrogen limitation, thereby facilitating relatively quick conversion of TCE to ethene. In general, hydrogen limitation is found to increase with increasing TCE concentration and with bioaugmentation, and

Influence of sediment on the fate and toxicity of a polyethoxylated tallowamine surfactant system (MON 0818) in aquatic microcosms

USGS Publications Warehouse

Wang, N.; Besser, J.M.; Buckler, D.R.; Honegger, J.L.; Ingersoll, C.G.; Johnson, B. Thomas; Kurtzweil, M.L.; MacGregor, J.; McKee, M.J.

2005-01-01

The fate and toxicity of a polyethoxylated tallowamine (POEA) surfactant system, MON 0818, was evaluated in water–sediment microcosms during a 4-d laboratory study. A surfactant solution of 8 mg l−1 nominal concentration was added to each of nine 72-l aquaria with or without a 3-cm layer of one of two natural sediments (total organic carbon (TOC) 1.5% or 3.0%). Control well water was added to each of nine additional 72-l aquaria with or without sediment. Water samples were collected from the microcosms after 2, 6, 24, 48, 72, and 96 h of aging to conduct 48-h toxicity tests with Daphnia magna and to determine surfactant concentrations. Elevated mortality of D. magna (43–83%) was observed in overlying water sampled from water-only microcosms throughout the 96-h aging period, whereas elevated mortality (23–97%) was only observed in overlying water sampled from water–sediment microcosms during the first 24 h of aging. Measured concentrations of MON 0818 in water-only microcosms remained relatively constant (4–6 mg l−1) during the 96-h period, whereas the concentrations in overlying water from microcosms containing either of the two types of sediment dissipated rapidly, with half-lives of 13 h in the 3.0% TOC sediment and 18 h in the 1.5% TOC sediment. Both toxicity and the concentration of MON 0818 in overlying water decreased more rapidly in microcosms containing sediment with the higher percent TOC and clay and with a higher microbial biomass. Mortality of D. magna was significantly correlated with surfactant concentrations in the overlying water. These results indicate that the toxicity of the POEA surfactant in water rapidly declines in the presence of sediment due to a reduction in the surfactant concentration in the overlying water above the sediment.

Nectar yeasts: a natural microcosm for ecology.

PubMed

Chappell, Callie R; Fukami, Tadashi

2018-06-01

The species of yeasts that colonize floral nectar can modify the mutualistic relationships between plants and pollinators by changing the chemical properties of nectar. Recent evidence supporting this possibility has led to increased interest among ecologists in studying these fungi as well as the bacteria that interact with them in nectar. Although not fully explored, nectar yeasts also constitute a promising natural microcosm that can be used to facilitate development of general ecological theory. We discuss the methodological and conceptual advantages of using nectar yeasts from this perspective, including simplicity of communities, tractability of dispersal, replicability of community assembly, and the ease with which the mechanisms of species interactions can be studied in complementary experiments conducted in the field and the laboratory. To illustrate the power of nectar yeasts as a study system, we discuss several topics in community ecology, including environmental filtering, priority effects, and metacommunity dynamics. An exciting new direction is to integrate metagenomics and comparative genomics into nectar yeast research to address these fundamental ecological topics. Copyright © 2018 John Wiley & Sons, Ltd.

Reduction of nitrate in aquifer microcosms by carbon additions

USGS Publications Warehouse

Obenhuber, Donald C.; Lowrance , Richard

1991-01-01

Aquifer microcosms were used to examine the effects of NO−3 and C amendments on groundwater from the Claiborne aquifer. Nitrate concentrations of 12.17 mg L−1 in aquifer microcosms were reduced 0.92%/d to 5.84 mg L−1 by the addition of 10 mg C L−1 for 35 d. Nitrate disappearance correlated with increases in number of denitrifiers and dissolved N2O concentration and decreases in dissolved oxygen, suggesting biological denitrification. Nitrate/chloride ratios decreased in microcosms with 10 mg C L−1 added and then increased when the C addition was removed. Carbon additions of 0.4 mg C L−1 had no effect on the microbial or chemical properties of the microcosms. Nitrous oxide levels in wells sampling the Claiborne aquifer showed an increase with depth, indicating N2O production within the aquifer. Microcosms are useful tools to examine biological transformations of chemical contaminants in unconsolidated aquifer material. The remediation of NO−3 contaminated aquifers by organic infusion is possible and appears to be a function of microbial denitrification.

Comparative meta-analysis and experimental kinetic investigation of column and batch bottle microcosm treatability studies informing in situ groundwater remedial design.

PubMed

Driver, Erin M; Roberts, Jeff; Dollar, Peter; Charles, Maurissa; Hurst, Paul; Halden, Rolf U

2017-02-05

A systematic comparison was performed between batch bottle and continuous-flow column microcosms (BMs and CMs, respectively) commonly used for in situ groundwater remedial design. Review of recent literature (2000-2014) showed a preference for reporting batch kinetics, even when corresponding column data were available. Additionally, CMs produced higher observed rate constants, exceeding those of BMs by a factor of 6.1±1.1 standard error. In a subsequent laboratory investigation, 12 equivalent microcosm pairs were constructed from fractured bedrock and perchloroethylene (PCE) impacted groundwater. First-order PCE transformation kinetics of CMs were 8.0±4.8 times faster than BMs (rates: 1.23±0.87 vs. 0.16±0.05d -1 , respectively). Additionally, CMs transformed 16.1±8.0-times more mass than BMs owing to continuous-feed operation. CMs are concluded to yield more reliable kinetic estimates because of much higher data density stemming from long-term, steady-state conditions. Since information from BMs and CMs is valuable and complementary, treatability studies should report kinetic data from both when available. This first systematic investigation of BMs and CMs highlights the need for a more unified framework for data use and reporting in treatability studies informing decision-making for field-scale groundwater remediation. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of two lubricant oils on marine nematode assemblages in a laboratory microcosm experiment.

PubMed

Beyrem, H; Louati, H; Essid, N; Aïssa, P; Mahmoudi, E

2010-05-01

The effects of two lubricating oils on nematode assemblages of a Tunisian lagoon were investigated in a microcosm experiment. Sediment from a pristine site in Ghar El Melh lagoon (Western Mediterranean) was treated with either mineral oil (Mobil 20 W-50), a synthetic lubricant (Mobil 0 W-40), the same two lubricants after use in a vehicle, and effects were examined after 5 weeks. Univariate analysis showed significant differences between most univariate indices of the nematode assemblages in all the lubricant treatments as compared to the control. Total nematode abundance (I), species richness (d) and number of species (S) decreased significantly in all lubricant contaminated microcosms. However, evenness was not affected in all treated replicates except in used mineral lubricant treatment where it was significantly higher than in the control. Diversity (H') was only altered in synthetic lubricant treatments. Results from multivariate analyses of the species abundance data demonstrated that responses of nematode species to the two lubricants treatments were varied: Daptonema trabeculosum was eliminated in all lubricant treatments and seemed to be an intolerant species to oil contamination. Spirinia gerlachi increased in mineral lubricant treatments ("clean" and used) but was eliminated in all synthetic lubricant treatments. This species could be categorized as "resistant" to mineral oil contamination and intolerant to synthetic lubricant contamination. Terschellingia longicaudata increased only in synthetic lubricant treatments ("clean" and used) and appeared to be a "synthetic oil-resistant" species. Copyright 2009 Elsevier Ltd. All rights reserved.

Microcosm Studies to Evaluate Aerobic Cometabolism of Low Concentrations of 1,4-Dioxane by Isobutane-utilizing Microorganisms in the Presence of Chlorinated Solvent Co-contaminants

NASA Astrophysics Data System (ADS)

Rolston, H. M.; Azizian, M.; Hyman, M. R.; Semprini, L.

2015-12-01

Due to its use as a stabilizer for chlorinated solvents, 1,4-dioxane (1,4D), a probable human carcinogen, is a common co-contaminant in solvent spills at industrial and military sites and landfills. Its persistence in large groundwater plumes at low concentrations makes it a relevant candidate for in-situ bioremediation via cometabolism. Microcosm studies are being performed to evaluate the capability of aerobic microorganisms to cometabolize mixtures of 1,4D and chlorinated solvents, such as trichloroethylene (TCE), 1,1,1-trichloroethane (1,1,1TCA), and 1,1-dichloroethene (1,1DCE), with isobutane as the primary substrate. Microcosms were constructed using aquifer solids from Fort Carson, Colorado, a site contaminated with 1,4D and TCE, to assess the isobutane uptake and transformation of 1,4D and chlorinated solvents by microorganisms native to the site. Additional microcosms were augmented with Rhodococcus rhodochrous, a bacterium shown to cometabolize 1,4D and chlorinated solvents. Results indicate that native microcosms cometabolized 1,4D upon stimulation with isobutane after a lag period of about 15 days. TCE was also transformed, but at significantly slower rates. The presence of 1,4D and TCE at 500 and 300 ppb, respectively, did not inhibit the growth of native microorganisms on isobutane, with isobutane uptake and 1,4D transformation occurring simultaneously. Bioaugmented microcosms transformed 1,4D immediately after inoculation with R. rhodochrous. Tests in bioaugmented microorganisms indicated that the presence of TCE at low concentrations inhibits but does not block the transformation of 1,4D. Results from the microcosms will be used to design field tests to be performed at Fort Carson. Additional microcosm studies will compare the stimulation of native and bioaugmented microcosms and the transformation of mixtures of 1,4D, 1,1,1TCA and 1,1DCE. Molecular methods will analyze the monoxygenase enzymes expressed in the native and bioaugmented microcosms.

Near-Complete Genome Sequence of Thalassospira sp. Strain KO164 Isolated from a Lignin-Enriched Marine Sediment Microcosm

DOE PAGES

Woo, Hannah L.; O’Dell, Kaela B.; Utturkar, Sagar; ...

2016-11-23

We isolated Thalassospirasp. strain KO164 from eastern Mediterranean seawater and sediment laboratory microcosms enriched on insoluble organosolv lignin under oxic conditions. Furthermore, an analysis of the deep-ocean bacterium’s ability to degrade recalcitrant organics such as lignin near-complete genome sequence, will be presented here.

Near-Complete Genome Sequence of Thalassospira sp. Strain KO164 Isolated from a Lignin-Enriched Marine Sediment Microcosm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woo, Hannah L.; O’Dell, Kaela B.; Utturkar, Sagar

We isolated Thalassospirasp. strain KO164 from eastern Mediterranean seawater and sediment laboratory microcosms enriched on insoluble organosolv lignin under oxic conditions. Furthermore, an analysis of the deep-ocean bacterium’s ability to degrade recalcitrant organics such as lignin near-complete genome sequence, will be presented here.

Ecotoxicological assessment of biosolids by microcosms.

PubMed

Groth, Vitor Avelar; Carvalho-Pereira, Ticiana; da Silva, Eduardo Mendes; Niemeyer, Júlia Carina

2016-10-01

Biosolids have been applied as soil amendments to improve and maintain the soil fertility and faster plant growth. In spite of its beneficial use, the potential risks of land disposal should be analyzed, considering potential ecological receptors in soil and water. This work describes the use of an early warning laboratory microcosm system to evaluate the integrated ecotoxicological potential of two biosolids: BIO-1 and BIO-2 (18 and 28 months after landfarming, respectively), from an effluent treatment station in a petrochemical and industrial district. The endpoints related to habitat function were: a) germination, growth and biomass of Phaseolus vulgaris; b) survival, biomass and number of cocoons of Eisenia andrei (Oligochaeta) and; c) reproduction of Folsomia candida (Collembola). The retention function was evaluated by testing the leachates using the tropical cladoceran Latonopsis australis (Cladocera) in a 48-h acute toxicity test, and growth of the aquatic plant Lemna minor in a 7-d chronic test. Tropical artificial soil (TAS) and a natural soil (NS) from the region were used as control soils. Results showed no chronic toxicity of BIO-1 and BIO-2 to the soil organisms tested, but acute toxicity of BIO-1 in the leachate for 50% of L. australis, and chronic toxicity of both biosolid leachates to L. minor (inhibition of growth rate), indicating potential risks to aquatic ecosystems. The results confirmed the ability of this microcosm system as a rapid tool to assess biosolid toxicity over time and its potential for hazardous waste characterization in environmental risk assessment, in a screening phase. Copyright © 2016 Elsevier Ltd. All rights reserved.

Near-Complete Genome Sequence of Thalassospira sp. Strain KO164 Isolated from a Lignin-Enriched Marine Sediment Microcosm

PubMed Central

Woo, Hannah L.; O’Dell, Kaela B.; Utturkar, Sagar; McBride, Kathryn R.; Huntemann, Marcel; Clum, Alicia; Pillay, Manoj; Palaniappan, Krishnaveni; Varghese, Neha; Mikhailova, Natalia; Stamatis, Dimitrios; Reddy, T. B. K.; Ngan, Chew Yee; Daum, Chris; Shapiro, Nicole; Markowitz, Victor; Ivanova, Natalia; Kyrpides, Nikos; Woyke, Tanja; Brown, Steven D.

2016-01-01

Thalassospira sp. strain KO164 was isolated from eastern Mediterranean seawater and sediment laboratory microcosms enriched on insoluble organosolv lignin under oxic conditions. The near-complete genome sequence presented here will facilitate analyses into this deep-ocean bacterium’s ability to degrade recalcitrant organics such as lignin. PMID:27881538

Methanogenic degradation kinetics of phenolic compounds in aquifer-derived microcosms

USGS Publications Warehouse

Godsy, E.M.; Goerlitz, D.F.; Grbic-Galic, D.

1992-01-01

In this segment of a larger multidisciplinary study of the movement and fate of creosote derived compounds in a sand-and-gravel aquifer, we present evidence that the methanogenic degradation of the major biodegradable phenolic compounds and concomitant microbial growth in batch microcosms derived from contaminated aquifer material can be described using Monod kinetics. Substrate depletion and bacterial growth curves were fitted to the Monod equations using nonlinear regression analysis. The method of Marquardt was used for the determination of parameter values that best fit the experimental data by minimizing the residual sum of squares. The Monod kinetic constants (??max, Ks, Y, and kd) that describe phenol, 2-, 3-, and 4-methylphenol degradation and concomitant microbial growth were determined under conditions that were substantially different from those previously reported for microcosms cultured from sewage sludge. The Ks values obtained in this study are approximately two orders of magnitude lower than values obtained for the anaerobic degradation of phenol in digesting sewage sludge, indicating that the aquifer microorganisms have developed enzyme systems that are adapted to low nutrient conditions. The values for kd are much less than ??max, and can be neglected in the microcosms. The extremely low Y values, approximately 3 orders of magnitude lower than for the sewage sludge derived cultures, and the very low numbers of microorganisms in the aquifer derived microcosms suggest that these organisms use some unique strategies to survive in the subsurface environment. ?? 1992 Kluwer Academic Publishers.

Quantitative survival of Leptospira interrogans in soil and water microcosms.

PubMed

Casanovas-Massana, Arnau; Pedra, Gabriel Ghizzi; Wunder, Elsio A; Diggle, Peter J; Begon, Mike; Ko, Albert I

2018-04-27

Leptospira interrogans is the etiological agent of leptospirosis, a globally distributed zoonotic disease. Human infection usually occurs through skin exposure with water and soil contaminated with the urine of chronically infected animals. In this study, we aimed to quantitatively characterize the survival of Leptospira interrogans serovar Copenhageni in environmental matrices. We constructed laboratory microcosms to simulate natural conditions and determined the persistence of DNA markers in soil, mud, spring water and sewage using a qPCR and a PMA-qPCR assay. We found that L. interrogans does not survive at high concentrations in the tested matrices. No net growth was detected in any of the experimental conditions and in all cases the concentration of the DNA markers targeted decreased from the beginning of the experiment following an exponential decay with a decreasing decay rate over time. After 12 and 21 days of incubation the spiked concentration of 10 6 L. interrogans cells/mL or g decreased to approximately 100 cells/mL or g in soil and spring water microcosms, respectively. Furthermore, culturable L. interrogans persisted at concentrations under the limit of detection by PMA-qPCR or qPCR for at least 16 days in soil and 28 days in spring water. Altogether our findings suggest that the environment is not a multiplication reservoir, but a temporary carrier of the L. interrogans Copenhageni, although the observed prolonged persistence at low concentrations may still enable the transmission of the disease. IMPORTANCE Leptospirosis is a zoonotic disease caused by spirochetes of the genus Leptospira that primarily affects impoverished populations worldwide. Although leptospirosis is transmitted by contact with water and soil, little is known about the ability of the pathogen to survive in the environment. In this study, we quantitatively characterized the survival of L. interrogans in environmental microcosms and found that although it cannot multiply in water

Near-Complete Genome Sequence of Thalassospira sp. Strain KO164 Isolated from a Lignin-Enriched Marine Sediment Microcosm.

PubMed

Woo, Hannah L; O'Dell, Kaela B; Utturkar, Sagar; McBride, Kathryn R; Huntemann, Marcel; Clum, Alicia; Pillay, Manoj; Palaniappan, Krishnaveni; Varghese, Neha; Mikhailova, Natalia; Stamatis, Dimitrios; Reddy, T B K; Ngan, Chew Yee; Daum, Chris; Shapiro, Nicole; Markowitz, Victor; Ivanova, Natalia; Kyrpides, Nikos; Woyke, Tanja; Brown, Steven D; Hazen, Terry C

2016-11-23

Thalassospira sp. strain KO164 was isolated from eastern Mediterranean seawater and sediment laboratory microcosms enriched on insoluble organosolv lignin under oxic conditions. The near-complete genome sequence presented here will facilitate analyses into this deep-ocean bacterium's ability to degrade recalcitrant organics such as lignin. Copyright © 2016 Woo et al.

The influence of nickel on the bioremediation of multi-component contaminated tropical soil: microcosm and batch bioreactor studies.

PubMed

Taketani, Natália Franco; Taketani, Rodrigo Gouvêa; Leite, Selma Gomes Ferreira; Rizzo, Andrea Camardella de Lima; Tsai, Siu Mui; da Cunha, Cláudia Duarte

2015-07-01

Large petrochemical discharges are responsible for organic and inorganic pollutants in the environment. The purpose of this study was to evaluate the influence of nickel, one of the most abundant inorganic element in crude oil and the main component of hydrogen catalysts for oil refining, on the microbial community structure in artificially petroleum-contaminated microcosms and in solid phase bioreactor studies. In the presence of metals, the oil biodegradation in microcosms was significantly delayed during the first 7 days of operation. Also, increasing amounts of moisture generated a positive influence on the biodegradation processes. The oil concentration, exhibiting the most negative influence at the end of the treatment period. Molecular fingerprinting analyses (denaturing gradient gel electrophoresis--DGGE) indicated that the inclusion of nickel into the contaminated soil promoted direct changes to the microbial community structure. By the end of the experiments, the results of the total petroleum hydrocarbons removal in the bioreactor and the microcosm were similar, but reductions in the treatment times were observed with the bioreactor experiments. An analysis of the microbial community structure by DGGE using various markers showed distinct behaviors between two treatments containing high nickel concentrations. The main conclusion of this study was that Nickel promotes a significant delay in oil biodegradation, despite having only a minor effect over the microbial community.

Toxicity of environmentally realistic concentrations of chlorpyrifos and terbuthylazine in indoor microcosms.

PubMed

Pereira, Ana Santos; Cerejeira, Maria José; Daam, Michiel A

2017-09-01

Few studies have been conducted into the evaluation of environmentally realistic pesticide mixtures using model ecosystems. In the present study, the effects of single and combined environmentally realistic concentrations of the herbicide terbuthylazine and the insecticide chlorpyrifos were evaluated using laboratory microcosms. Direct toxic effects of chlorpyrifos were noted on copepod nauplii and cladocerans and the recovery of the latter was likely related with the decrease observed in rotifer abundances. Terbuthylazine potentiated the effect of chlorpyrifos on feeding rates of Daphnia magna, presumably by triggering the transformation of chlorpyrifos to more toxic oxon-analogs. Possible food-web interactions resulting from multiple chemical (and other) stressors likely to be present in edge-of-field water bodies need to be further evaluated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mercury Distribution, Methylation and Volatilization in Microcosms with and without the Sea Anemone Bunodosoma caissarum

NASA Astrophysics Data System (ADS)

Ansari, N. R.; Correia, R. R. S.; Fernandez, M. A. S.; Cordeiro, R. C.; Guimarães, J. R. D.

2014-12-01

Mercury (Hg) can be a dangerous contaminant and has a complex biogeochemical cycling in aquatic environments. The sea anemone Bunodosoma caissarum is an endemic species in Brazil capable of bioaccumulating Hg from the ambient seawater. The radiotracer 203Hg was used in order to investigate mechanisms of Hg uptake and depuration of B. caissarum and the distribution of Hg in laboratory model systems, with and without B. caissarum. A single initial spike of 203Hg was added to each microcosm. Microcosms had continuous air renovation and trapping of Hg volatile forms. Total Hg in different compartments was measured by gamma spectrometry. In the uptake experiment 203Hg activity was determined periodically in seawater and specimens for 6 days. At the end, specimens had an average bioconcentration factor of 70. After the uptake experiment, methylmercury (MeHg) in seawater was extracted and measured by liquid scintillation. In microcosms with and without B. caissarum, respectively 0.05% and 0.32% of the initial spike was found as MeHg. Hg was probably less available for methylation in the first because of bioaccumulation and higher concentrations of suspended particulate matter that could form complexes with Hg. After that, specimens were transferred to unspiked microcosms. After a 48 day depuration specimens still retained 35 - 70% of the previously bioaccumulated Hg and 0.2 - 2.4% of the total Hg was MeHg. The presence of B. caissarum resulted in an unexpected higher volatilization of Hg (58%) compared to controls (17%). This increased volatilization is possibly a result of Hg2+ reduction mediated by microorganisms associated with its tissues and mucus secretions and/or an unknown defense mechanism of this species.

Glyceria maxima as new test species for the EU risk assessment for herbicides: a microcosm study.

PubMed

Mohr, S; Schott, J; Hoenemann, L; Feibicke, M

2015-03-01

In its recent guidance document on tiered risk assessment for plant protection products for aquatic organisms, the European Food Safety Authority (EFSA) proposed to use Glyceria maxima as monocotyledonous grass species for the testing of special herbicide groups. However, published toxicity data for this species is very limited and there is no test guideline for Glyceria sp. For this reason a microcosm study was conducted in order to gain experience on the degree of sensitivity of G. maxima to the herbicidal substances clodinafop-propargyl (grass herbicide) and fluroxypyr (auxin) in comparison to the already established test organism water milfoil Myriophyllum spicatum and the duckweed species Landoltia punctata. Five concentrations without replicates were tested for each test substance using 10 microcosms and three microcosms served as controls. The experiment was run for 8 weeks. Morphological endpoints were used to determine growth and EC50 values. The results show that M. spicatum was most sensitive to fluroxypyr (37 days EC50 for roots: 62 µg/L) and G. maxima most sensitive to clodinafop-propargyl (22 days EC50 for total shoot length: 48 µg/L) whereas the duckweed species was considerable less sensitive. Hence, G. maxima turns out to be a good candidate for testing grass specific herbicides, supporting its inclusion as an additional macrophyte test for the risk assessment of herbicides as proposed by the EFSA.

SOME EFFECTS OF CADMIUM ON CONIFEROUS FOREST SOIL AND LITTER MICROCOSMS

EPA Science Inventory

Description and criticism is given of a preliminary design and use of a soil/litter microcosm in which oxygen, temperature, and humidity are kept constant, and oxygen generation and carbon dioxide and heat evolution rates are monitored. Using four microcosms, one acting as a dead...

Bacterial Community Response to Petroleum Hydrocarbon Amendments in Freshwater, Marine, and Hypersaline Water-Containing Microcosms

PubMed Central

Jurelevicius, Diogo; Alvarez, Vanessa Marques; Marques, Joana Montezano; de Sousa Lima, Laryssa Ribeiro Fonseca; Dias, Felipe de Almeida

2013-01-01

Hydrocarbon-degrading bacterial communities from freshwater, marine, and hypersaline Brazilian aquatic ecosystems (with water salinities corresponding to 0.2%, 4%, and 5%, respectively) were enriched with different hydrocarbons (heptadecane, naphthalene, or crude oil). Changes within the different microcosms of bacterial communities were analyzed using cultivation approaches and molecular methods (DNA and RNA extraction, followed by genetic fingerprinting and analyses of clone libraries based on the 16S rRNA-coding gene). A redundancy analysis (RDA) of the genetic fingerprint data and a principal component analysis (PCA) of the clone libraries revealed hydrocarbon-enriched bacterial communities specific for each ecosystem studied. However, within the same ecosystem, different bacterial communities were selected according to the petroleum hydrocarbon used. In general, the results demonstrated that Acinetobacter and Cloacibacterium were the dominant genera in freshwater microcosms; the Oceanospirillales order and the Marinobacter, Pseudomonas, and Cycloclasticus genera predominated in marine microcosms; and the Oceanospirillales order and the Marinobacter genus were selected in the different hydrocarbon-containing microcosms in hypersaline water. Determination of total petroleum hydrocarbons (TPHs) in all microcosms after 32 days of incubation showed a decrease in the hydrocarbon concentration compared to that for the controls. A total of 50 (41.3%) isolates from the different hydrocarbon-contaminated microcosms were associated with the dominant operational taxonomic units (OTUs) obtained from the clone libraries, and their growth in the hydrocarbon contaminating the microcosm from which they were isolated as the sole carbon source was observed. These data provide insight into the general response of bacterial communities from freshwater, marine, and hypersaline aquatic ecosystems to petroleum hydrocarbon contamination. PMID:23872573

Entry of Yersinia pestis into the viable but nonculturable state in a low-temperature tap water microcosm.

PubMed

Pawlowski, David R; Metzger, Daniel J; Raslawsky, Amy; Howlett, Amy; Siebert, Gretchen; Karalus, Richard J; Garrett, Stephanie; Whitehouse, Chris A

2011-03-16

Yersinia pestis, the causative agent of plague, has caused several pandemics throughout history and remains endemic in the rodent populations of the western United States. More recently, Y. pestis is one of several bacterial pathogens considered to be a potential agent of bioterrorism. Thus, elucidating potential mechanisms of survival and persistence in the environment would be important in the event of an intentional release of the organism. One such mechanism is entry into the viable but non-culturable (VBNC) state, as has been demonstrated for several other bacterial pathogens. In this study, we showed that Y. pestis became nonculturable by normal laboratory methods after 21 days in a low-temperature tap water microcosm. We further show evidence that, after the loss of culturability, the cells remained viable by using a variety of criteria, including cellular membrane integrity, uptake and incorporation of radiolabeled amino acids, and protection of genomic DNA from DNase I digestion. Additionally, we identified morphological and ultrastructural characteristics of Y. pestis VBNC cells, such as cell rounding and large periplasmic spaces, by electron microscopy, which are consistent with entry into the VBNC state in other bacteria. Finally, we demonstrated resuscitation of a small number of the non-culturable cells. This study provides compelling evidence that Y. pestis persists in a low-temperature tap water microcosm in a viable state yet is unable to be cultured under normal laboratory conditions, which may prove useful in risk assessment and remediation efforts, particularly in the event of an intentional release of this organism.

Entry of Yersinia pestis into the Viable but Nonculturable State in a Low-Temperature Tap Water Microcosm

PubMed Central

Pawlowski, David R.; Metzger, Daniel J.; Raslawsky, Amy; Howlett, Amy; Siebert, Gretchen; Karalus, Richard J.; Garrett, Stephanie; Whitehouse, Chris A.

2011-01-01

Yersinia pestis, the causative agent of plague, has caused several pandemics throughout history and remains endemic in the rodent populations of the western United States. More recently, Y. pestis is one of several bacterial pathogens considered to be a potential agent of bioterrorism. Thus, elucidating potential mechanisms of survival and persistence in the environment would be important in the event of an intentional release of the organism. One such mechanism is entry into the viable but non-culturable (VBNC) state, as has been demonstrated for several other bacterial pathogens. In this study, we showed that Y. pestis became nonculturable by normal laboratory methods after 21 days in a low-temperature tap water microcosm. We further show evidence that, after the loss of culturability, the cells remained viable by using a variety of criteria, including cellular membrane integrity, uptake and incorporation of radiolabeled amino acids, and protection of genomic DNA from DNase I digestion. Additionally, we identified morphological and ultrastructural characteristics of Y. pestis VBNC cells, such as cell rounding and large periplasmic spaces, by electron microscopy, which are consistent with entry into the VBNC state in other bacteria. Finally, we demonstrated resuscitation of a small number of the non-culturable cells. This study provides compelling evidence that Y. pestis persists in a low-temperature tap water microcosm in a viable state yet is unable to be cultured under normal laboratory conditions, which may prove useful in risk assessment and remediation efforts, particularly in the event of an intentional release of this organism. PMID:21436885

Alteration of Rock Fragments from Columbia River Basalt Microcosms

NASA Technical Reports Server (NTRS)

Wentworth, Susan J.; Thomas-Keprta, Kathie L.; Velbel, Michael A.; McKay, David S.; Stevens, Todd O.

1999-01-01

During an earlier study, microorganisms were grown microcosms consisting of sterilized chips of Columbia River Basalt (CRB) and natural CRB ground water with its natural microflora; environmental conditions simulated a deep subsurface, anaerobic, dark environment. Subsequent scanning and transmission electron microscope (SEM and TEM) studies revealed the presence of several types of bacteria and biofilm, some of which were mineralized. Some of these biological features are very similar to possible biogenic features found in two meteorites from Mars, ALH84001 (found in Antarctica) and Nakhla (observed to fall in Egypt). Both ALH84001 and Nakhla contain traces of low-temperature aqueous alteration of silicates, oxides, and sulfides. The goals of this study are to use high-resolution field-emission SEM (FE-SEM) to examine the CRB samples for evidence of alteration features similar to those in the martian meteorites, to determine the extent of alteration during the CRB microcosm experiments, and to determine whether effects of biological activity can be distinguished from inorganic effects.

Pyrene degradation in forest humus microcosms with or without pine and its mycorrhizal fungus.

PubMed

Koivula, Teija T; Salkinoja-Salonen, Mirja; Peltola, Rainer; Romantschuk, Martin

2004-01-01

The mineralization potential of forest humus and the self-cleaning potential of a boreal coniferous forest environment for polycyclic aromatic hydrocarbon (PAH) compounds was studied using a model ecosystem of acid forest humus (pH = 3.6) and pyrene as the model compound. The matrix was natural humus or humus mixed with oil-polluted soil in the presence and absence of Scots pine (Pinus sylvestris L.) and its mycorrhizal fungus (Paxillus involutus). The rates of pyrene mineralization in the microcosms with humus implants (without pine) were initially insignificant but increased from Day 64 onward to 47 microg kg(-1) d(-1) and further to 144 microg kg(-1) d(-1) after Day 105. In the pine-planted humus microcosms the rate of mineralization also increased, reaching 28 microg kg(-1) d(-1) after Day 105. The 14CO2 emission was already considerable in nonplanted microcosms containing oily soil at Day 21 and the pyrene mineralization continued throughout the study. The pyrene was converted to CO2 at rates of 0.07 and 0.6 microg kg(-1) d(-1) in the oily-soil implanted microcosms with and without pine, respectively. When the probable assimilation of 14CO2 by the pine and ground vegetation was taken into account the most efficient microcosm mineralized 20% of the 91.2 mg kg(-1) pyrene in 180 d. The presence of pine and its mycorrhizal fungus had no statistically significant effect on mineralization yields. The rates of pyrene mineralization observed in this study for forest humus exceeded the total annual deposition rate of PAHs in southern Finland. This indicates that accumulation in forest soil is not to be expected.

Enhanced and stabilized arsenic retention in microcosms through the microbial oxidation of ferrous iron by nitrate

DOE PAGES

Sun, Jing; Chillrud, Steven N.; Mailloux, Brian J.; ...

2015-10-23

Magnetite strongly retains As, and is relatively stable under Fe(III)-reducing conditions common in aquifers that release As. In this paper, laboratory microcosm experiments were conducted to investigate a potential As remediation method involving magnetite formation, using groundwater and sediments from the Vineland Superfund site. The microcosms were amended with various combinations of nitrate, Fe(II) (aq) (as ferrous sulfate) and lactate, and were incubated for more than 5 weeks. In the microcosms enriched with 10 mM nitrate and 5 mM Fe(II) (aq), black magnetic particles were produced, and As removal from solution was observed even under sustained Fe(III) reduction stimulated bymore » the addition of 10 mM lactate. The enhanced As retention was mainly attributed to co-precipitation within magnetite and adsorption on a mixture of magnetite and ferrihydrite. Sequential chemical extraction, X-ray absorption spectroscopy and magnetic susceptibility measurements showed that these minerals formed at pH 6–7 following nitrate-Fe(II) addition, and As-bearing magnetite was stable under reducing conditions. Scanning electron microscopy and X-ray diffraction indicated that nano-particulate magnetite was produced as coatings on fine sediments, and no aging effect was detected on morphology over the course of incubation. Finally, these results suggest that a magnetite based strategy may be a long-term remedial option for As-contaminated aquifers.« less

U(VI) bioreduction with emulsified vegetable oil as the electron donor--microcosm tests and model development.

PubMed

Tang, Guoping; Wu, Wei-Min; Watson, David B; Parker, Jack C; Schadt, Christopher W; Shi, Xiaoqing; Brooks, Scott C

2013-04-02

We conducted microcosm tests and biogeochemical modeling to study U(VI) reduction in contaminated sediments amended with emulsified vegetable oil (EVO). Indigenous microorganisms in the sediments degraded EVO and stimulated Fe(III), U(VI), and sulfate reduction, and methanogenesis. Acetate concentration peaked in 100-120 days in the EVO microcosms versus 10-20 days in the oleate microcosms, suggesting that triglyceride hydrolysis was a rate-limiting step in EVO degradation and subsequent reactions. Acetate persisted 50 days longer in oleate- and EVO- than in ethanol-amended microcosms, indicating that acetate-utilizing methanogenesis was slower in the oleate and EVO than ethanol microcosms. We developed a comprehensive biogeochemical model to couple EVO hydrolysis, production, and oxidation of long-chain fatty acids (LCFA), glycerol, acetate, and hydrogen, reduction of Fe(III), U(VI) and sulfate, and methanogenesis with growth and decay of multiple functional microbial groups. By estimating EVO, LCFA, and glycerol degradation rate coefficients, and introducing a 100 day lag time for acetoclastic methanogenesis for oleate and EVO microcosms, the model approximately matched observed sulfate, U(VI), and acetate concentrations. Our results confirmed that EVO could stimulate U(VI) bioreduction in sediments and the slow EVO hydrolysis and acetate-utilizing methanogens growth could contribute to longer term bioreduction than simple substrates (e.g., ethanol, acetate, etc.) in the subsurface.

Naturally-Derived Microcosms for Estimating Stress Effects in Aquatic Ecosystems

DTIC Science & Technology

1991-05-31

production, respiration, nutrient dynamics, enzyme activities, and species richness. Endpoints can be added or eliminated, depending on the...substrates per microcosm, depending on the experimental design. One to two substrates per microcosm will be placed in a natural ecosystem to accumulate the...water, these substrates should be left to accumulate microbiota for 3-10 d, depending on the flow rate and sediment load. In lentic ecosystems, exposure

Know Thyself: Macrocosm and Microcosm

ERIC Educational Resources Information Center

Tubbs, Nigel

2011-01-01

There was a time when, in the Liberal Arts, philosophy and education enjoyed the most intimate and productive relationship. Drawing together philosophy and nature they sought to understand the greatest of human mysteries. This meant thinking about both the macrocosm and the microcosm and especially the relation between them. In this relation lies…

Fate and bioaccumulation of isoproturon in outdoor aquatic microcosms.

PubMed

Merlin, Gerard; Vuillod, Maryline; Lissolo, Thierry; Clement, Bernard

2002-06-01

To gain information concerning the ecotoxicity of isoproturon (IPU) on aquatic ecosystems, six experimental ponds of 5 m3 each were studied. All the experiments were conducted during the summer over two years. Three different types of ecosystems were tested in 1994 and one type of ecosystem was selected and repeated in 1995 with three replicates. In each case, the initial concentration of IPU contamination was set at 10 microg/L. The IPU concentration was determined in the water column and in different species (mainly plants) of the microcosms. A first-order kinetic decrease in IPU concentration was observed in 1994, with half-life ranging from 15 to 35 d, depending on the microcosms. This relatively fast decrease was also confirmed in 1995, but it reached a constant value after two months. A high variability of the IPU concentration was observed in exposed plants, with bioconcentration factors ranging from 100 to 1,200 with large coefficients of variation. The observed plant bioconcentration factors are higher than those predicted by usual numerical models, probably due to the specific binding of IPU on one protein of the photosynthetic apparatus. Our data show that bioconcentration does not occur in mollusks but is important in photosynthetic organisms. Plant bioconcentration and microbial biodegradation are the main processes involved in the IPU decay in our outdoor aquatic microcosms.

Azolla-anabaena-bacteria system as a natural microcosm

NASA Astrophysics Data System (ADS)

Carrapico, Francisco J.

2002-02-01

Azolla is an aquatic fern that contains a permanent endosymbiotic prokaryotic community (cyanobacteria and bacteria) inside of the cavity in the leaf dorsal lobe of the pteridophyte. This is a unique situation and can be seen as a microcosm inside of an organism and also can be considered a good example of a living model for biological and environmental studies. These symbionts are specific of this symbiosis and lives immobilized in a mucilaginous fibrillar network, which fills part of the cavity. The symbionts works as immobilized organisms in a natural system that can be used as a model for biotechnological research and in biologically based life support systems. The nature and the complexity of this system is simultaneously a reference and a challenge for the research in the communication between the two levels of nature organization (microcosm and mesocosm), and can also be used as a reference for the design of new environmental engineered symbiotic systems that include man as a prelude to life in space.

Ecological changes in oral microcosm biofilm during maturation

NASA Astrophysics Data System (ADS)

Kim, Young-Seok; Kang, Si-Mook; Lee, Eun-Song; Lee, Ji Hyun; Kim, Bo-Ra; Kim, Baek-Il

2016-10-01

The aim of this study was to evaluate the ecological changes in the biofilm at different stages of maturation using 16S rDNA gene amplicon sequencing and to identify correlations between red/green (R/G) fluorescence ratio and ecological changes. An oral microcosm biofilm was initiated from the saliva of a single donor and grown anaerobically for up to 10 days in basal medium mucin. Quantitative light-induced fluorescence analysis was shown that the R/G ratio of the biofilm increased consistently, but the slope rapidly decreased after six days. The bacterial compositions of 10 species also consistently changed over time. However, there was no significant correlation between each bacteria and red fluorescence. The monitoring of the maturation process of oral microcosm biofilm over 10 days revealed that the R/G ratio and the bacterial composition within biofilm consistently changed. Therefore, the R/G fluorescence ratio of biofilm may be related with its ecological change rather than specific bacteria.

Growth of ammonia-oxidizing archaea in soil microcosms is inhibited by acetylene.

PubMed

Offre, Pierre; Prosser, James I; Nicol, Graeme W

2009-10-01

Autotrophic ammonia-oxidizing bacteria were considered to be responsible for the majority of ammonia oxidation in soil until the recent discovery of the autotrophic ammonia-oxidizing archaea. To assess the relative contributions of bacterial and archaeal ammonia oxidizers to soil ammonia oxidation, their growth was analysed during active nitrification in soil microcosms incubated for 30 days at 30 degrees C, and the effect of an inhibitor of ammonia oxidation (acetylene) on their growth and soil nitrification kinetics was determined. Denaturing gradient gel electrophoresis (DGGE) analysis of bacterial ammonia oxidizer 16S rRNA genes did not detect any change in their community composition during incubation, and quantitative PCR (qPCR) analysis of bacterial amoA genes indicated a small decrease in abundance in control and acetylene-containing microcosms. DGGE fingerprints of archaeal amoA and 16S rRNA genes demonstrated changes in the relative abundance of specific crenarchaeal phylotypes during active nitrification. Growth was also indicated by increases in crenarchaeal amoA gene copy number, determined by qPCR. In microcosms containing acetylene, nitrification and growth of the crenarchaeal phylotypes were suppressed, suggesting that these crenarchaea are ammonia oxidizers. Growth of only archaeal but not bacterial ammonia oxidizers occurred in microcosms with active nitrification, indicating that ammonia oxidation was mostly due to archaea in the conditions of the present study.

Stability and resilience of oral microcosms toward acidification and Candida outgrowth by arginine supplementation.

PubMed

Koopman, Jessica E; Röling, Wilfred F M; Buijs, Mark J; Sissons, Christopher H; ten Cate, Jacob M; Keijser, Bart J F; Crielaard, Wim; Zaura, Egija

2015-02-01

Dysbiosis induced by low pH in the oral ecosystem can lead to caries, a prevalent bacterial disease in humans. The amino acid arginine is one of the pH-elevating agents in the oral cavity. To obtain insights into the effect of arginine on oral microbial ecology, a multi-plaque "artificial mouth" (MAM) biofilm model was inoculated with saliva from a healthy volunteer and microcosms were grown for 4 weeks with 1.6 % (w/v) arginine supplement (Arginine) or without (Control), samples were taken at several time-points. A cariogenic environment was mimicked by sucrose pulsing. The bacterial composition was determined by 16S rRNA gene amplicon sequencing, the presence and amount of Candida and arginine deiminase system genes arcA and sagP by qPCR. Additionally, ammonium and short-chain fatty acid concentrations were determined. The Arginine microcosms were dominated by Streptococcus, Veillonella, and Neisseria and remained stable in time, while the composition of the Control microcosms diverged significantly in time, partially due to the presence of Megasphaera. The percentage of Candida increased 100-fold in the Control microcosms compared to the Arginine microcosms. The pH-raising effect of arginine was confirmed by the pH and ammonium results. The abundances of sagP and arcA were highest in the Arginine microcosms, while the concentration of butyrate was higher in the Control microcosms. We demonstrate that supplementation with arginine serves a health-promoting function; it enhances microcosm resilience toward acidification and suppresses outgrowth of the opportunistic pathogen Candida. Arginine facilitates stability of oral microbial communities and prevents them from becoming cariogenic.

Anaerobic degradation of vinyl chloride in aquifer microcosms.

PubMed

Smits, Theo H M; Assal, Antoine; Hunkeler, Daniel; Holliger, Christof

2011-01-01

The anaerobic degradation potential at a chloroethene-contaminated site was investigated by operating two anoxic column aquifer microcosms enriched in iron(III). One column was fed with vinyl chloride (VC) only (column A) and one with VC and acetate (column B). In column A, after about 600 pore volume exchanges (PVEs), VC started to disappear and reached almost zero VC recovery in the effluent after 1000 PVEs. No formation of ethene was observed. In column B, effluent VC was almost always only a fraction of influent VC. Formation of ethene was observed after 800 PVEs and started to become an important degradation product after 1550 PVEs. However, ethene was never observed in stoichiometric amounts compared with disappeared VC. The average stable isotope enrichment factor for VC disappearance in column A was determined to be -4.3‰. In column B, the isotope enrichment factor shifted from -10.7 to -18.5‰ concurrent with an increase in ethene production. Batch microcosms inoculated with column material showed similar isotope enrichment factors as the column microcosms. These results indicated that two degradation processes occurred, one in column A and two in parallel in column B with increasing importance of reductive dechlorination with time. This study suggests that in addition to reductive dechlorination, other degradation processes such as anaerobic oxidation should be taken into account when evaluating natural attenuation of VC and that isotope analysis can help to differentiate between different pathways of VC removal. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

A DNA Origami Mechanical Device for the Regulation of Microcosmic Structural Rigidity.

PubMed

Wan, Neng; Hong, Zhouping; Wang, Huading; Fu, Xin; Zhang, Ziyue; Li, Chao; Xia, Han; Fang, Yan; Li, Maoteng; Zhan, Yi; Yang, Xiangliang

2017-11-01

DNA origami makes it feasible to fabricate a tremendous number of DNA nanostructures with various geometries, dimensions, and functionalities. Moreover, an increasing amount of research on DNA nanostructures is focused on biological and biomedical applications. Here, the reversible regulation of microcosmic structural rigidity is accomplished using a DNA origami device in vitro. The designed DNA origami monomer is composed of an internal central axis and an external sliding tube. Due to the external tube sliding, the device transforms between flexible and rigid states. By transporting the device into the liposome, the conformational change of the origami device induces a structural change in the liposome. The results obtained demonstrate that the programmed DNA origami device can be applied to regulate the microcosmic structural rigidity of liposomes. Because microcosmic structural rigidity is important to cell proliferation and function, the results obtained potentially provide a foundation for the regulation of cell microcosmic structural rigidity using DNA nanostructures. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of decabromodiphenyl ether and planting on the abundance and community composition of nitrogen-fixing bacteria and ammonia oxidizers in mangrove sediments: A laboratory microcosm study.

PubMed

Chen, Juan; Wang, Pei-Fang; Wang, Chao; Wang, Xun; Gao, Han

2018-03-01

While nitrogen (N) fixation and ammonia oxidation by microorganisms are two important N cycling processes, little is known about how the microbes that drive these two processes respond when sediments are contaminated with persistent organic pollutants. In this study, we carried out a laboratory microcosm experiment to examine the effects of decabromodiphenyl ether (BDE-209), either on its own or combined with a common mangrove species, Avicennia marina, on the abundance, diversity, and community composition of N-fixing bacteria (NFB) and ammonia-oxidizing archaea (AOA) and bacteria (AOB) in mangrove sediments. The sediments were very N-limited after one year. The rates of N fixation and NFB abundance were significantly higher in the sediments that contaminated by BDE-209, especially in the planted sediment, indicating that both BDE-209 and planting stimulated N fixation in N-limited mangrove sediments. In contrast, the potential nitrification rate and abundance of AOA and AOB decreased significantly under BDE-209 and planting, and the inhibitory effects were stronger in the sediment with both planting and BDE-209 than in the sediments with either BDE-209 or planting. The results from pyrosequencing showed that the richness and diversity of NFB increased, while those of AOA and AOB decreased, in the sediments treated with BDE-209 only and with BDE-209 combined with planting. The community compositions of NFB, AOA, and AOB in the sediments shifted significantly because of BDE-209, either alone or particularly when combined with planting, as shown by the increases in some NFB from the Proteobacteria phylum and decreases in AOA in the Nitrosopumilus genus and AOB in the Nitrosospira genus, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessing microbial responses to iron enrichment in the Subarctic Northeast Pacific: Do microcosms reproduce the in situ condition?

NASA Astrophysics Data System (ADS)

Scarratt, M. G.; Marchetti, A.; Hale, M. S.; Rivkin, R. B.; Michaud, S.; Matthews, P.; Levasseur, M.; Sherry, N.; Merzouk, A.; Li, W. K. W.; Kiyosawa, H.

2006-10-01

A microcosm experiment was conducted in the NE Pacific in July 2002 to compare the microbial response between microcosms and the Subarctic Ecosystem Response to Iron-Enrichment Study (SERIES) in situ iron-enrichment experiment. Seawater microcosms (20 L) were incubated aboard ship under natural light using three treatments: (1) low-iron seawater amended with 4 nmol l -1 FeSO 4 (+Fe); (2) low-iron seawater amended with 4 nmol l -1 FeSO 4 and 86 nmol l -1 GeO 2 (+Fe+Ge); (3) seawater collected from the in situ Fe-enriched patch (PW). The +Fe+Ge treatment used germanium to control diatom growth to assess the role of diatoms in dimethylsulfoniopropionate (DMSP) production. The following variables were measured in the microcosms and in situ: chlorophyll a (chl a), nitrate ( NO3-), silicic acid (Si(OH) 4), phytoplankton abundance and species identification, bacterial abundance (including estimates of low- and high-DNA bacteria), bacterial production, bacterial specific growth rate, particulate and dissolved DMSP and dimethylsulfide (DMS) concentrations. There was little or no significant difference (ANCOVA) in the response of most variables between the +Fe and PW microcosms, but large differences were observed between both these treatments and the in situ data from the enriched patch. Chl a in all microcosms increased from ambient levels (approx. 0.5-1 μg l -1) to approx. 4.5-6.2 μg l -1 after 11 d incubation, when NO3- was fully depleted from all microcosms. During this same period, in situ chl a increased more slowly to a maximum of 2.9 μg l -1 on day 11. Nanophytoplankton and picophytoplankton were more abundant in the microcosms relative to the in situ community, which became dominated by large diatoms. Bacterial abundance was similar in the microcosms and in situ, but bacterial production was significantly higher in the microcosms. While neither DMSP d nor DMS accumulation showed significant differences between the microcosms and in situ , particulate DMSP

Methods for visualising active microbial benzene degraders in in situ microcosms.

PubMed

Schurig, Christian; Mueller, Carsten W; Höschen, Carmen; Prager, Andrea; Kothe, Erika; Beck, Henrike; Miltner, Anja; Kästner, Matthias

2015-01-01

Natural attenuation maybe a cost-efficient option for bioremediation of contaminated sites but requires knowledge about the activity of degrading microbes under in situ conditions. In order to link microbial activity to the spatial distribution of contaminant degraders, we combined the recently improved in situ microcosm approach, so-called 'direct-push bacterial trap' (DP-BACTRAP), with nano-scale secondary ion mass spectrometry (NanoSIMS) analysis on samples from contaminated constructed wetlands. This approach is based on initially sterile microcosms amended with (13)C-labelled benzene as a source of carbon and energy for microorganisms. The microcosms were introduced directly in the constructed wetland, where they were colonised by indigenous microorganisms from the sediment. After incubation in the field, the samples were analysed by NanoSIMS, scanning electron microscopy (SEM) and fluorescence microscopy in order to visualise (13)C-labelled microbial biomass on undisturbed samples from the microcosms. With the approach developed, we successfully visualised benzene-degrading microbes on solid materials with high surface area by means of NanoSIMS. Moreover, we could demonstrate the feasibility of NanoSIMS analysis of unembedded porous media with a highly complex topography, which was frequently reasoned to not lead to sufficient results.

Distribution and bioaccumulation of selenium in aquatic microcosms

USGS Publications Warehouse

Besser, John M.; Huckins, James N.; Little, Edward E.; La Point, Thomas W.

1989-01-01

Closed-system microcosms were used to study factors affecting the fate of selenium (Se) in aquatic systems. Distribution and bioaccumulation of Se varied among sediment types and Se species. A mixture of dissolved 75Se species (selenate, selenite and selenomethionine) was sorbed more rapidly to fine-textured, highly organic pond sediments than to sandy riverine sediments. Sulfate did not affect the distribution and bioaccumulation of 75Se over the range 80–180 mg SO4 liter−1. When each Se species was labeled separately, selenomethionine was lost from the water column more rapidly than selenate or selenite. Selenium lost from the water column accumulated primarily in sediments, but volatilization was also an important pathway for loss of Se added as selenomethionine. Loss rates of dissolved Se residues were more rapid than rates reported from mesocosm and field studies, suggesting that sediment: water interactions are more important in microcosms than in larger test systems. Daphnids accumulated highest concentrations of Se, followed by periphyton and macrophytes. Selenium added as selenomethionine was bioaccumulated preferentially compared to that added as selenite or selenate. Organoselenium compounds such as selenomethione may thus contribute disproportionately to Se bioaccumulation and toxicity in aquatic organisms.

Direct and indirect effects of the fungicide azoxystrobin in outdoor brackish water microcosms.

PubMed

Gustafsson, Kerstin; Blidberg, Eva; Elfgren, Irene Karlsson; Hellström, Anna; Kylin, Henrik; Gorokhova, Elena

2010-02-01

The effects of the strobilurin fungicide azoxystrobin were studied in brackish water microcosms, with natural plankton communities and sediment. Two experiments were conducted: Experiment 1 (nominal conc. 0, 15 and 60 microg/L, 24-L outdoor microcosms for 21 days) and a second, follow-up, Experiment 2 (nominal conc. 0, 3, 7.5, 15 microg/L, 4-L indoor microcosms for 12 days). The microcosms represent a simplified brackish water community found in shallow semi-enclosed coastal areas in agricultural districts in the Baltic Sea region. Measured water concentrations of the fungicide (Experiment 1) were, on average, 83 and 62% of nominal concentrations directly after application, and 25 and 30% after 21 days, for the low and high dose treatments, respectively, corresponding to mean DT50-values of 15.1 and 25.8 days, for low and high dose treatments, respectively. In Experiment 1, direct toxic effects on calanoid copepods at both test concentrations were observed. Similarly, in Experiment 2, the copepod abundance was significantly reduced at all tested concentrations. There were also significant secondary effects on zooplankton and phytoplankton community structure, standing stocks and primary production. Very few ecotoxicological studies have investigated effects of plant protection products on Baltic organisms in general and effects on community structure and function specifically. Our results show that azoxystrobin is toxic to brackish water copepods at considerably lower concentrations than previously reported from single species tests on freshwater crustaceans, and that direct toxic effects on this ecologically important group may lead to cascade effects altering lower food webs and ecosystem functioning.

Comparison of an Assay for Dehalococcoides DNA and a Microcosm Study in Predicting Reductive Dechlorination of Chlorinated Ethenes in the field

EPA Science Inventory

The study aims to compare the detection of 16S rRNA gene of Dehalococcoides species and the microcosm study for biotransformation in predicting reductive dechlorination of chlorinated ethylenes in ground water at hazardous waste sites. A total of 72 ground water samples were coll...

Trichloroethylene biodegradation by mesophilic and psychrophilic ammonia oxidizers and methanotrophs in groundwater microcosms.

PubMed Central

Moran, B N; Hickey, W J

1997-01-01

This study investigated the efficiency of methane and ammonium for stimulating trichloroethylene (TCE) biodegradation in groundwater microcosms (flasks and batch exchange columns) at a psychrophilic temperature (12 degrees C) typical of shallow aquifers in the northern United States or a mesophilic temperature (24 degrees C) representative of most laboratory experiments. After 140 days, TCE biodegradation rates by ammonia oxidizers and methanotrophs in mesophilic flask microcosms were similar (8 to 10 nmol day-1), but [14C]TCE mineralization (biodegradation to 14CO2) by ammonia oxidizers was significantly greater than that by methanotrophs (63 versus 53%). Under psychrophilic conditions, [14C]TCE mineralization in flask systems by ammonia oxidizers and methanotrophs was reduced to 12 and 5%, respectively. In mesophilic batch exchange columns, average TCE biodegradation rates for methanotrophs (900 nmol liter-1 day-1) were not significantly different from those of ammonia oxidizers (775 nmol liter-1 day-1). Psychrophilic TCE biodegradation rates in the columns were similar with both biostimulants and averaged 145 nmol liter-1 day-1. Methanotroph biostimulation was most adversely affected by low temperatures. At 12 degrees C, the biodegradation efficiencies (TCE degradation normalized to microbial activity) of methanotrophs and ammonia oxidizers decreased by factors of 2.6 and 1.6, respectively, relative to their biodegradation efficiencies at 24 degrees C. Collectively, these experiments demonstrated that in situ bioremediation of TCE is feasible at the psychrophilic temperatures common in surficial aquifers in the northern United States and that for such applications biostimulation of ammonia oxidizers could be more effective than has been previously reported. PMID:9327550

Impact of protists on a hydrocarbon-degrading bacterial community from deep-sea Gulf of Mexico sediments: A microcosm study

NASA Astrophysics Data System (ADS)

Beaudoin, David J.; Carmichael, Catherine A.; Nelson, Robert K.; Reddy, Christopher M.; Teske, Andreas P.; Edgcomb, Virginia P.

2016-07-01

In spite of significant advancements towards understanding the dynamics of petroleum hydrocarbon degrading microbial consortia, the impacts (direct or indirect via grazing activities) of bacterivorous protists remain largely unknown. Microcosm experiments were used to examine whether protistan grazing affects the petroleum hydrocarbon degradation capacity of a deep-sea sediment microbial community from an active Gulf of Mexico cold seep. Differences in n-alkane content between native sediment microcosms and those treated with inhibitors of eukaryotes were assessed by comprehensive two-dimensional gas chromatography following 30-90 day incubations and analysis of shifts in microbial community composition using small subunit ribosomal RNA gene clone libraries. More biodegradation was observed in microcosms supplemented with eukaryotic inhibitors. SSU rRNA gene clone libraries from oil-amended treatments revealed an increase in the number of proteobacterial clones (particularly γ-proteobacteria) after spiking sediments with diesel oil. Bacterial community composition shifted, and degradation rates increased, in treatments where protists were inhibited, suggesting protists affect the hydrocarbon degrading capacity of microbial communities in sediments collected at this Gulf of Mexico site.

Exposure and effects of sediment-spiked fludioxonil on macroinvertebrates and zooplankton in outdoor aquatic microcosms.

PubMed

Yin, Xiao H; Brock, Theo C M; Barone, Lidia E; Belgers, J Dick M; Boerwinkel, Marie-Claire; Buijse, Laura; van Wijngaarden, René P A; Hamer, Mick; Roessink, Ivo

2018-01-01

Information from effects of pesticides in sediments at an ecosystem level, to validate current and proposed risk assessment procedures, is scarce. A sediment-spiked outdoor freshwater microcosm experiment was conducted with fludioxonil (lipophilic, non-systemic fungicide) to study exposure dynamics and treatment-related responses of benthic and pelagic macroinvertebrates and zooplankton. Besides blank control and solvent control systems the experiment had six different treatment levels (1.7-614mga.s./kg dry sediment) based around the reported 28-d No Observed Effect Concentration (NOEC) for Chironomus riparius (40mga.s./kg dry sediment). Twelve systems were available per treatment of which four were sacrificed on each of days 28, 56 and 84 after microcosm construction. Fludioxonil persisted in the sediment and mean measured concentrations were 53-82% of the initial concentration after 84days. The dissipation rate increased with the treatment level. Also exposure concentrations in overlying water were long-term, with highest concentrations 28days after initiation of the experiment. Sediment-dwelling Oligochaeta and pelagic Rotifera and Cladocera showed the most pronounced treatment-related declines. The most sensitive sediment-dwelling oligochaete was Dero digitata (population NOEC 14.2mga.s./kg dry sediment). The same NOEC was calculated for the sediment-dwelling macroinvertebrate community. The most sensitive zooplankton species was the cladoceran Diaphanosoma brachyurum (NOEC of 1.6μga.s./L in overlying water corresponding to 5.0mga.s./kg dry sediment). At the two highest treatments several rotifer taxa showed a pronounced decrease, while the zooplankton community-level NOEC was 5.6μga.s./L (corresponding to 14.2mga.s./kg dry sediment). Zooplankton taxa calanoid Copepoda and Daphnia gr. longispina showed a pronounced treatment-related increase (indirect effects). Consequently, an assessment factor of 10 to the chronic laboratory NOECs of Chironomus riparius

Design of Mixed Batch Reactor and Column Studies at Oak Ridge National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Weimin; Criddle, Craig S.

2015-11-16

We (the Stanford research team) were invited as external collaborators to contribute expertise in environmental engineering and field research at the ORNL IFRC, Oak Ridge, TN, for projects carried out at the Argonne National Laboratory and funded by US DOE. Specifically, we assisted in the design of batch and column reactors using ORNL IFRC materials to ensure the experiments were relevant to field conditions. During the funded research period, we characterized ORNL IFRC groundwater and sediments in batch microcosm and column experiments conducted at ANL, and we communicated with ANL team members through email and conference calls and face-to-face meetingsmore » at the annual ERSP PI meeting and national meetings. Microcosm test results demonstrated that U(VI) in sediments was reduced to U(IV) when amended with ethanol. The reduced products were not uraninite but unknown U(IV) complexes associated with Fe. Fe(III) in solid phase was only partially reduced. Due to budget reductions at ANL, Stanford contributions ended in 2011.« less

Dissipation of 2,4-D in soils of the Humid Pampa region, Argentina: a microcosm study.

PubMed

Merini, Luciano J; Cuadrado, Virginia; Flocco, Cecilia G; Giulietti, Ana M

2007-06-01

Phenoxy herbicides like 2,4-dichlorophenoxyacetic acid (2,4-D) are widely used in agricultural practices. Although its half life in soil is 7-14d, the herbicide itself and its first metabolite 2,4-dichlorophenol (2,4-DCP) could remain in the soil for longer periods, as a consequence of its intensive use. Microcosms assays were conducted to study the influence of indigenous microflora and plants (alfalfa) on the dissipation of 2,4-D from soils of the Humid Pampa region, Argentina, with previous history of phenoxy herbicides application. Results showed that 2,4-D was rapidly degraded, and the permanence of 2,4-DCP in soil depended on the presence of plants and soil microorganisms. Regarding soil microbial community, the presence of 2,4-D degrading bacteria was detected even in basal conditions in this soil, possibly due to the adaptation of the microflora to the herbicide. There was an increment of two orders of magnitude in herbicide degraders after 15d from 2,4-D addition, both in planted and unplanted microcosms. Total heterotrophic bacteria numbers were about 1x10(8) CFUg(-1) dry soil and no significant differences were found between different treatments. Overall, the information provided by this work indicates that the soil under study has an important intrinsic degradation capacity, given by a microbial community adapted to the presence of phenoxy herbicides.

[Exploration of microcosmic Chinese medicine used by western medicine].

PubMed

Zheng, Zhi-jing

2015-02-01

"Microcosmic syndrome", "treatment based on syndrome differentiation", and "combination of disease identification and syndrome differentiation" generally refer to a mode: following the syndrome if with no disease identified, following the disease if with no syndrome type differentiated. For example, Chinese medical treatment of hypertension, high blood lipids, increased transaminase, and so on candirectly use Chinese recipes, but no longer with syndrome differentiation. Clinical application of Chinese patent medicine can also obtain favorable clinical. Western doctors need not follow syndrome differentiation. The invention of artemisinin was screened from more than 40 000 kinds of compounds and herbs, but with no reference of any traditional Chinese medical theory. A lot of folk remedy and empirical recipes have obtained effective efficacy but unnecessarily with profound Chinese medical theories. Various evidences showed that disease can also be cured without syndrome differentiation. I held that it might be associated with the same mechanism of Chinese medicine and Western medicine. Any disease can be cured or alleviated by Chinese medicine is a result from its modern pharmacological effect, which is achieved by improving etiologies, and pathogeneses. I was inspired by whether we can directly use traditional Chinese medicine with modern pharmacological effects to treat symptomatic disease. So I raised an idea of microcosmic Chinese medicine used by Western medicine, i.e., we find and use Chinese herbs with relatively effective modern pharmacological effect to treat diseases targeting at patients' clinical symptoms and signs, as well as various positive laboratory results (collectively called as microscopic dialectical indicators). More Western doctors would use it to treat disease due to omission of complicated and mysterious syndrome differentiation. This will promote extensive application and expansion of Chi- nese medicine and pharmacy, enlarge the team of

Special Education: A Microcosm of Bureaucracy. Part Two: The Elements of the System

ERIC Educational Resources Information Center

Clark, Ann D.

1971-01-01

Delineates a case study of special education that provides a unique microcosm of the emergence of an educational subsystem with inherent and forceful bureaucratic controls that were present from its inception. (Author)

Evaluated fate and effects of atrazine and lambda-cyhalothrin in vegetated and unvegetated microcosms.

PubMed

Bouldin, J L; Farris, J L; Moore, M T; Smith, S; Stephens, W W; Cooper, C M

2005-10-01

Contaminants such as nutrients, metals, and pesticides can interact with constructed wetlands and existing drainage ditches used as agricultural best-management practices. Our research has shown that the presence of macrophytes and a hydrologic regime aid in the transfer and transformation of pesticides associated with agricultural runoff. This study consisted of application of both atrazine (triazine herbicide) and lambda-cyhalothrin (pyrethroid insecticide) to vegetated and unvegetated microcosms in order to measure the fate and effects of pesticides applied at suggested field application rates. Exposures focused on monocultures of Ludwigia peploides (water primrose) and Juncus effusus (soft rush). Pesticide sorption was evident through concentrations of atrazine and lambda-cyhalothrin in plant tissue as high as 2461.4 and 86.50 microg/kg, respectively. Toxicity was measured in water from unvegetated microcosms for 28 days and in Chironomus tentans (midge larvae) exposed to sediment collected from 3 h to 56 days in microcosms receiving the pesticide combination. The comparative survival of test organisms in this study suggests that effective mitigation of pesticides from runoff can depend on the macrophyte contact and vegetative attributes associated with ditches. (c) 2005 Wiley Periodicals, Inc.

Variation of nonylphenol-degrading gene abundance and bacterial community structure in bioaugmented sediment microcosm.

PubMed

Wang, Zhao; Yang, Yuyin; Sun, Weimin; Dai, Yu; Xie, Shuguang

2015-02-01

Nonylphenol (NP) can accumulate in river sediment. Bioaugmentation is an attractive option to dissipate heavy NP pollution in river sediment. In this study, two NP degraders were isolated from crude oil-polluted soil and river sediment. Microcosms were constructed to test their ability to degrade NP in river sediment. The shift in the proportion of NP-degrading genes and bacterial community structure in sediment microcosms were characterized using quantitative PCR assay and terminal restriction fragment length polymorphism analysis, respectively. Phylogenetic analysis indicated that the soil isolate belonged to genus Stenotrophomonas, while the sediment isolate was a Sphingobium species. Both of them could almost completely clean up a high level of NP in river sediment (150 mg/kg NP) in 10 or 14 days after inoculation. An increase in the proportion of alkB and sMO genes was observed in sediment microcosms inoculated with Stenotrophomonas strain Y1 and Sphingobium strain Y2, respectively. Moreover, bioaugmentation using Sphingobium strain Y2 could have a strong impact on sediment bacterial community structure, while inoculation of Stenotrophomonas strain Y1 illustrated a weak impact. This study can provide some new insights towards NP biodegradation and bioremediation.

Exposure of Sink Drain Microcosms to Triclosan: Population Dynamics and Antimicrobial Susceptibility

PubMed Central

McBain, Andrew J.; Bartolo, Robert G.; Catrenich, Carl E.; Charbonneau, Duane; Ledder, Ruth G.; Price, Bradford B.; Gilbert, Peter

2003-01-01

Recent concern that the increased use of triclosan (TCS) in consumer products may contribute to the emergence of antibiotic resistance has led us to examine the effects of TCS dosing on domestic-drain biofilm microcosms. TCS-containing domestic detergent (TCSD) markedly lowered biofouling at 50% (wt/vol) but was poorly effective at use levels. Long-term microcosms were established and stabilized for 6 months before one was subjected to successive 3-month exposures to TCSD at sublethal concentrations (0.2 and 0.4% [wt/vol]). Culturable bacteria were identified by 16S rDNA sequence analysis, and their susceptibilities to four biocides and six antibiotics were determined. Microcosms harbored ca. 10 log10 CFU/g of biofilm, representing at least 27 species, mainly gamma proteobacteria, and maintained dynamic stability. Viable cell counts were largely unaffected by TCSD exposure, but species diversity was decreased, as corroborated by denaturing gradient gel electrophoresis analysis. TCS susceptibilities ranged widely within bacterial groups, and TCS-tolerant strains (including aeromonads, pseudomonads, stenotrophomonads, and Alcaligenes spp.) were isolated before and after TCSD exposure. Several TCS-tolerant bacteria related to Achromobacter xylosoxidans became clonally expanded during dosing. TCSD addition did not significantly affect the community profiles of susceptibility to the test biocides or antibiotics. Several microcosm isolates, as well as reference bacteria, caused clearing of particulate TCS in solid media. Incubations of consortia and isolates with particulate TCS in liquid led to putative TCS degradation by the consortia and TCS solubilization by the reference strains. Our results support the view that low-level exposure of environmental microcosms to TCS does not affect antimicrobial susceptibility and that TCS is degradable by common domestic biofilms. PMID:12957932

The fate and transport of the Cry1Ab protein in an agricultural field and laboratory aquatic microcosms.

PubMed

Strain, Katherine E; Lydy, Michael J

2015-08-01

Genetically engineered crops expressing insecticidal crystalline proteins derived from Bacillus thuringiensis (Bt), were commercialized almost two decades ago as a means to manage agricultural pests. The Bt proteins are highly specific and only lethal upon ingestion, limiting the scope of toxicity to target insects. However, concern of exposure to non-target organisms and negative public perceptions regarding Bt crops has caused controversy surrounding their use. The objective of this research was to monitor the fate and transport of a Bt protein, Cry1Ab, in a large-scale agricultural field containing maize expressing the Cry1Ab protein and a non-Bt near isoline, and in aquatic microcosms. The highest environmental concentrations of the Cry1Ab protein were found in runoff water and sediment, up to 130ngL(-1) and 143ngg(-1) dry weight, respectively, with the Cry1Ab protein detected in both Bt and non-Bt maize fields. As surface runoff and residual crop debris can transport Bt proteins to waterways adjacent to agricultural fields, a series of laboratory experiments were conducted to determine the potential fate of the Cry1Ab protein under different conditions. The results showed that sediment type and temperature can influence the degradation of the Cry1Ab protein in an aquatic system and that the Cry1Ab protein can persist for up to two months. Although Cry1Ab protein concentrations measured in the field soil indicate little exposure to terrestrial organisms, the consistent input of Bt-contaminated runoff and crop debris into agricultural waterways is relevant to understanding potential consequences to aquatic species. Copyright © 2015 Elsevier Ltd. All rights reserved.

Two-dimensional flow-through microcosms - Versatile test systems to study biodegradation processes in porous aquifers

NASA Astrophysics Data System (ADS)

Bauer, Robert D.; Rolle, Massimo; Kürzinger, Petra; Grathwohl, Peter; Meckenstock, Rainer U.; Griebler, Christian

2009-05-01

SummaryA fundamental prerequisite of any remedial activity is a sound knowledge of both the biotic and abiotic processes involved in transport and degradation of contaminants. Investigations of these aspects in situ often seem infeasible due to the complexity of interacting processes. A simplified portrayal of nature can be facilitated in laboratory-based two-dimensional (2D) sediment flow-through microcosms. This paper describes the versatility of such simple aquifer model systems with respect to biodegradation of aromatic hydrocarbons, i.e. toluene and ethylbenzene, under various environmental conditions. Initially constructed to study non-reactive and bioreactive transport of organic contaminants in homogeneous porous media under steady state hydraulic conditions, experimental setups developed towards more realistic heterogeneous sediment packing and transient hydraulic conditions. High-resolution spatial and temporal sampling allowed to obtain new insights on the distribution of bioactivities in contaminant plumes and associated controlling and limiting factors. Major biodegradation activities in saturated porous sediments are located at the fringes of contaminant plumes and are driven by dispersive mixing. These hot-spots of contaminant biotransformation are characterized by steep physical-chemical gradients in the millimeter to centimeter range. Sediment heterogeneity, i.e. high-conductivity zones, was shown to significantly enhance transverse mixing and subsequently biodegradation. On the contrary, transient hydraulic conditions may generate intermediate disturbances to biodegrader populations and thus may interfere with optimized contaminant conversion. However, a bacterial strain aerobically degrading toluene, i.e. Pseudomonas putida F1, was shown to adapt to vertically moving contaminant plumes, in the way that it regained full biodegradation potential two-times faster in areas with a mid-term (days to weeks) contamination history than in areas not

Modelling biological Cr(VI) reduction in aquifer microcosm column systems.

PubMed

Molokwane, Pulane E; Chirwa, Evans M N

2013-01-01

Several chrome processing facilities in South Africa release hexavalent chromium (Cr(VI)) into groundwater resources. Pump-and-treat remediation processes have been implemented at some of the sites but have not been successful in reducing contamination levels. The current study is aimed at developing an environmentally friendly, cost-effective and self-sustained biological method to curb the spread of chromium at the contaminated sites. An indigenous Cr(VI)-reducing mixed culture of bacteria was demonstrated to reduce high levels of Cr(VI) in laboratory samples. The effect of Cr(VI) on the removal rate was evaluated at concentrations up to 400 mg/L. Following the detailed evaluation of fundamental processes for biological Cr(VI) reduction, a predictive model for Cr(VI) breakthrough through aquifer microcosm reactors was developed. The reaction rate in batch followed non-competitive rate kinetics with a Cr(VI) inhibition threshold concentration of approximately 99 mg/L. This study evaluates the application of the kinetic parameters determined in the batch reactors to the continuous flow process. The model developed from advection-reaction rate kinetics in a porous media fitted best the effluent Cr(VI) concentration. The model was also used to elucidate the logistic nature of biomass growth in the reactor systems.

Screening Spanish isolates of steinernematid nematodes for use as biological control agents through laboratory and greenhouse microcosm studies.

PubMed

Campos-Herrera, Raquel; Gutiérrez, Carmen

2009-02-01

Entomopathogenic nematodes (EPNs) are one of the best non-chemical alternatives for insect pest control, with native EPN strains that are adapted to local conditions considered to be ideal candidates for regional biological control programs. Virulence screening of 17 native Mediterranean EPN strains was performed to select the most promising strain for regional insect pest control. Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) Rioja strain produced 7%, 91% and 33% larval mortality for the insects Agriotes sordidus (Illiger) (Coleoptera: Elateridae), Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) and Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), respectively, and was selected as the most promising strain. The S. feltiae Rioja strain-S. littoralis combination was considered the most suitable to develop the Rioja strain as a biocontrol agent for soil applications. The effect of soil texture on the virulence of the Rioja strain against S. littoralis was determined through dose-response experiments. The estimated LC(90) to kill larvae in two days was 220, 753 and 4178 IJs/cm(2) for soils with a clay content of 5%, 14% and 24%, respectively, which indicates that heavy soils produced negative effects on the virulence of the Rioja strain. The nematode dose corresponding to the LC(90) for soils with a 5% and 14% clay content reduced insect damage to Capsicum annuum Linnaeus (Solanales: Solanaceae) plants under greenhouse microcosm conditions. The results of this research suggest that an accurate characterization of new EPN strains to select the most suitable combination of insect, nematode and soil texture might provide valuable data to obtain successful biological control under different ecological scenarios in future field applications.

Fitness trade-offs modify community composition under contrasting disturbance regimes in Pseudomonas fluorescens microcosms.

PubMed

Engelmoer, Daniel J P; Rozen, Daniel E

2009-11-01

Disturbance is thought to be a major factor influencing patterns of biodiversity. In addition, disturbance can modify community composition if there are species specific trade-offs between fitness and disturbance tolerance. Here, we examine the role of disturbance on the evolution of coexisting biofilm-forming morphotypes of Pseudomonas fluorescens maintained in spatially structured laboratory microcosms. We identified four heritably stable ecotypes that varied significantly in their competitiveness under different disturbance treatments. Furthermore, we identified significant trade-offs in competitiveness across disturbance treatments for three of four of these ecotypes. These trade-offs modified dominance relationships between strains and thus altered community composition, with a peak of ecotype diversity occurring at intermediate disturbance frequencies.

Microcosm studies of subsurface PAH-degrading bacteria from a former manufactured gas plant

NASA Astrophysics Data System (ADS)

Durant, Neal D.; Wilson, Liza P.; Bouwer, Edward J.

1995-01-01

A study was conducted to evaluate the potential for natural in situ biodegradation of polycyclic aromatic hydrocarbons (PAH's) in the subsurface at the site of a former manufactured gas plant. Fifty-seven samples of unconsolidated subsurface sediments were aseptically obtained from five boreholes across the site. Bacteria capable of aerobically degrading PAH's without an acclimation period were detected throughout shallow (2.7 m) and deep (24.7 m) areas of the subsurface in both relatively clean (<20 μg L -1 naphthalene) and contaminated (4400 μg L -1 naphthalene) zones. Significant ( p < 0.05) quantities of naphthalene (8±3% to 43±7%) and/or phenanthrene (3±1% to 31±3%) were mineralized in sediment-groundwater microcosms during 4 weeks of aerobic incubation at 22°C. Three samples out of 11 were able to aerobically mineralize significant quantities of benzene (6±2% to 24±1%). Of 11 samples tested for anaerobic mineralization, naphthalene biodegradation (7±1% to 13±2%) in the presence of N03 was observed in two samples. Compound removals were first order with respect to substrate concentration during the first 10-15 days of incubation. Compound biodegradation plateaued in the later stages of incubation (15-40 days), most likely from diminishing bioavailability and nutrient and oxygen depletion. Population densities in the sediments were typically low, with viable aerobic counts ranging from 0 to 10 5 CFU gdw -1, viable anaerobic counts ranging from 0 to 104 CFU gdw -1, and total counts (AODC) usually 10-fold greater than viable counts. Total counts exhibited a strong ( p < 0.01) positive correlation with sample grain size. Viable aerobic and anaerobic populations commonly occurred in the same sample, suggesting the presence of facultative anaerobes. Bacteria were metabolically active in samples from groundwaters with low pH (3.7) and high naphthalene concentrations (11,000 μg L -1). Data from these enumeration and microcosm studies suggest that natural

Degradation of 1,1,2,2-tetrachloroethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: biogeochemical controls and associations with microbial communities

NASA Astrophysics Data System (ADS)

Lorah, Michelle M.; Voytek, Mary A.

2004-05-01

The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as microcosms constructed with sediment that was methanogenic only throughout the incubation. The microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction. Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens

Degradation of 1,1,2,2-tetrachloroethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: biogeochemical controls and associations with microbial communities

USGS Publications Warehouse

Lorah, Michelle M.; Voytek, Mary A.

2004-01-01

The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as microcosms constructed with sediment that was methanogenic only throughout the incubation. The microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction.Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens

Degradation of 1,1,2,2-tetrachloroethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: Biogeochemical controls and associations with microbial communities

USGS Publications Warehouse

Lorah, M.M.; Voytek, M.A.

2004-01-01

The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as microcosms constructed with sediment that was methanogenic only throughout the incubation. The microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction. Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens

From a microcosm to the catchment scale: studying the fate of organic runoff pollutants in aquatic ecosystems

NASA Astrophysics Data System (ADS)

Böttcher, T.; Schroll, R.

2009-04-01

Spray-drift, drainage, erosion and runoff events are the major causes responsible for deportation of agrochemicals as micropollutants to aquatic non-target sites. These processes can lead to the contamination of nearby freshwater ecosystems with considerably high concentrations of xenobiotics. Thus, it is important to unravel the fate of these pollutants and to evaluate their ecological effects. A novel approach to address this goal was established by the development of a microcosm with multiple sampling abilities enabling quantitative assessment of organic volatilisation, mineralization, metabolization and distribution within the aquatic ecosystem. This microcosm system was designed to support modelling approaches of the catchment scale and gain insights into the fate of pesticides simulating a large scale water body. The potential of this microcosm was exemplified for Isoproturon (IPU), a phenylurea derived systemic herbicide, which is frequently found as contaminant in water samples and with the free-floating macrophyte Lemna minor as non-target species, that is common to occur in rural water bodies. During 21 days exposure time, only a small amount of 14C labeled IPU was removed from the aquatic medium. The major portion (about 5%) was accumulated by Lemna minor resulting in a BCF of 15.8. IPU-volatilisation was very low with 0.13% of the initially applied herbicide. Only a minor amount of IPU was completely metabolized, presumably by rhizosphere microorganisms and released as 14CO2. The novel experimental system allowed to quantitatively investigate the fate of IPU and showed a high reproducibility with a mean average 14C-recovery rate of 97.1

Monitoring Uranium Transformations Determined by the Evolution of Biogeochemical Processes: Design of Mixed Batch Reactor and Column Studies at Oak Ridge National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Criddle, Craig S.; Wu, Weimin

2013-04-17

With funds provided by the US DOE, Argonne National Laboratory subcontracted the design of batch and column studies to a Stanford University team with field experience at the ORNL IFRC, Oak Ridge, TN. The contribution of the Stanford group ended in 2011 due to budget reduction in ANL. Over the funded research period, the Stanford research team characterized ORNL IFRC groundwater and sediments and set up microcosm reactors and columns at ANL to ensure that experiments were relevant to field conditions at Oak Ridge. The results of microcosm testing demonstrated that U(VI) in sediments was reduced to U(IV) with themore » addition of ethanol. The reduced products were not uraninite but were instead U(IV) complexes associated with Fe. Fe(III) in solid phase was only partially reduced. The Stanford team communicated with the ANL team members through email and conference calls and face to face at the annual ERSP PI meeting and national meetings.« less

A Semi-Quantitative Study of the Impact of Bacterial Pollutant Uptake Capability on Bioremediation in a Saturated Sand-Packed Two-Dimensional Microcosm: Experiments and Simulation

NASA Astrophysics Data System (ADS)

Zheng, S.; Ford, R.; Van den Berg, B.

2016-12-01

The transport of microorganisms through the saturated porous matrix of soil is critical to the success of bioremediation in polluted groundwater systems. Chemotaxis can direct the movement of microorganisms toward higher concentration of pollutants, which they chemically transform and use as carbon and energy sources, resulting in enhanced bioremediation efficiency. In addition to accessibility and degradation kinetics, bacterial uptake of the pollutants is a critical step in bioremediation. In order to study the impact of bacterial pollutant uptake capability on bioremediation, a two-dimensional microcosm packed with saturated sand was set up to mimic the natural groundwater system where mass transfer limitation poses a barrier (see the figure below). Toluene source was continuously injected into the microcosm from an injection port. Pseudomonas putida F1, either wild-type (WT) or genetic mutants (TodX knockout, TodX and CymD knockout) that exhibited impaired toluene uptake capability, were co-injected with a conservative tracer into the microcosm either above or below the toluene. After each run, samples were collected from a dozen effluent ports to determine the concentration profiles of the bacteria and tracers. Toluene serves as the only carbon source throughout the microcosm. So the percent recovery, which is the ratio of cells collected at the outlet over that at the inlet, can be used as the indicator for bioremediation efficiency. Comparisons were made between the WT and mutant strains, where PpF1 WT showed greater proliferation than the mutants. Comparisons for low and high toluene source concentrations showed that the PpF1 mutant strains exhibited a greater degree of growth inhibition than WT at higher toluene concentration. A mathematical model was applied to evaluate the impact of various parameters on toluene uptake illustrating that with reasonable parameter estimates, the bioremediation efficiency was more sensitive to proliferation than transport

Gonadal development of larval male Xenopus laevis exposed to atrazine in outdoor microcosms

USGS Publications Warehouse

Jooste, A.M.; Du Preez, L.H.; Carr, J.A.; Giesy, J.P.; Gross, T.S.; Kendall, R.J.; Smith, E.E.; Van Der Kraak, G. L.; Solomon, K.R.

2005-01-01

The potential effects of atrazine on gonadal development in metamorphs and subadults of the African clawed frog (Xenopus laevis) were studied under conditions of natural photoperiod and temperatures in outdoor microcosms from August 2002 to June 2003 in South Africa. Triplicate 1100 L microcosms for each nominal concentration of 0.0, 1, 10, and 25 ??g of atrazine/L were used. Measured atrazine concentrations varied <25% throughout the study, and no atrazine was detected in the control microcosms. Tadpoles developed well at all concentrations. On the basis of histological examination of testes of recently metamorphosed stage 66 frogs, 57% of the individuals in the reference group exhibited testicular oocytes as compared with 57, 59, and 39% of the 1, 10, and 25 ??g/L atrazine groups, respectively. The average prevalence of testicular oocytes for all of the treatments including the controls was 54% in a single testis, while, in 35% of individuals, testicular oocytes were observed in both testes. The number of testicular oocytes per individual ranged from 0 to 58 with means of 9.5, 9.8, 8.5, and 11.1 for the 0.0, 1, 10, and 25 ??g of atrazine/L groups, respectively. Ten months after metamorphosis, another subset of juveniles was examined, and the maximum number of testicular oocytes observed was five in one animal. The presence of testicular oocytes was not related to exposure to atrazine and may be a natural phenomenon during ontogeny. ?? 2005 American Chemical Society.

Effects of the fungicide metiram in outdoor freshwater microcosms: responses of invertebrates, primary producers and microbes.

PubMed

Lin, Ronghua; Buijse, Laura; Dimitrov, Mauricio R; Dohmen, Peter; Kosol, Sujitra; Maltby, Lorraine; Roessink, Ivo; Sinkeldam, Jos A; Smidt, Hauke; Van Wijngaarden, René P A; Brock, Theo C M

2012-07-01

The ecological impact of the dithiocarbamate fungicide metiram was studied in outdoor freshwater microcosms, consisting of 14 enclosures placed in an experimental ditch. The microcosms were treated three times (interval 7 days) with the formulated product BAS 222 28F (Polyram®). Intended metiram concentrations in the overlying water were 0, 4, 12, 36, 108 and 324 μg a.i./L. Responses of zooplankton, macroinvertebrates, phytoplankton, macrophytes, microbes and community metabolism endpoints were investigated. Dissipation half-life (DT₅₀) of metiram was approximately 1-6 h in the water column of the microcosm test system and the metabolites formed were not persistent. Multivariate analysis indicated treatment-related effects on the zooplankton (NOEC(community) = 36 μg a.i./L). Consistent treatment-related effects on the phytoplankton and macroinvertebrate communities and on the sediment microbial community could not be demonstrated or were minor. There was no evidence that metiram affected the biomass, abundance or functioning of aquatic hyphomycetes on decomposing alder leaves. The most sensitive populations in the microcosms comprised representatives of Rotifera with a NOEC of 12 μg a.i./L on isolated sampling days and a NOEC of 36 μg a.i./L on consecutive samplings. At the highest treatment-level populations of Copepoda (zooplankton) and the blue-green alga Anabaena (phytoplankton) also showed a short-term decline on consecutive sampling days (NOEC = 108 μg a.i./L). Indirect effects in the form of short-term increases in the abundance of a few macroinvertebrate and several phytoplankton taxa were also observed. The overall community and population level no-observed-effect concentration (NOEC(microcosm)) was 12-36 μg a.i./L. At higher treatment levels, including the test systems that received the highest dose, ecological recovery of affected measurement endpoints was fast (effect period < 8 weeks).

Short-term emissions of ammonia and carbon dioxide from cattle urine contaminated tropical grassland microcosm.

PubMed

Majumdar, Deepanjan; Patel, Manoj; Drabar, Reena; Vyas, Manish

2006-11-01

The study was designed to understand the emissions of ammonia (NH(3)) and carbon dioxide (CO(2)) from a single cattle urination event on a tropical grassland and underline the significance of the emissions in the context of huge animal population grazing on large pasture areas in some countries. Emissions of ammonia (NH(3)) and carbon dioxide (CO(2)) were monitored for three weeks from a tropical grassland (dominated by Cynodon dactylon Pers.) microcosm contaminated with cow and buffalo urine. The grassland microcosms were treated with urine (50 and 100 ml of each) only once and irrigated with water once every week. Ammonia was sampled by an automatic sampling system comprising of a vacuum pump, three-way stopcocks and rubber tubing and an impinger containing suitable absorbing solution (H(2)SO(4)), connected to the tubing suitably. The sampled gas, after sucked by the vacuum pump and absorbed in H(2)SO(4), was allowed to enter the closed microcosm again maintaining internal pressure of the microcosm. Carbon dioxide was sampled by absorption in an alkali (NaOH) trap inside the microcosm. Both NH(3) and CO(2) emissions were highly variable temporally and there was no continuous increasing or decreasing emission trend with time. Respectively, 45 and 46% of total NH(3)-N were emitted within first 48 h from 50 and 100 ml cow urine application while the corresponding values for buffalo urine were 34 and 32%. Total NH(3)-N emissions, integrated for sampling days (i.e. 1, 2, 3, 4, 6, 15, 18 and 21st) were 11 and 6% in cow and 8 and 5% in buffalo urine, of the total-N added through 50 and 100 ml urine samples. Carbon dioxide emissions were standardized at 25 degrees C by using a suitable formula which were lower than actual emissions at actual soil temperature (> 25 degrees C). Carbon dioxide emission rates were classified on the basis of soil repiratory classification and classes ranged from moderately low soil activity up to unusually high soil activity, the latter

Morphological Alteration and Survival of Burkholderia pseudomallei in Soil Microcosms

PubMed Central

Kamjumphol, Watcharaporn; Chareonsudjai, Pisit; Taweechaisupapong, Suwimol; Chareonsudjai, Sorujsiri

2015-01-01

The resilience of Burkholderia pseudomallei, the causative agent of melioidosis, was evaluated in control soil microcosms and in soil microcosms containing NaCl or FeSO4 at 30°C. Iron (Fe(II)) promoted the growth of B. pseudomallei during the 30-day observation, contrary to the presence of 1.5% and 3% NaCl. Scanning electron micrographs of B. pseudomallei in soil revealed their morphological alteration from rod to coccoid and the formation of microcolonies. The smallest B. pseudomallei cells were found in soil with 100 μM FeSO4 compared with in the control soil or soil with 0.6% NaCl (P < 0.05). The colony count on Ashdown's agar and bacterial viability assay using the LIVE/DEAD® BacLight™ stain combined with flow cytometry showed that B. pseudomallei remained culturable and viable in the control soil microcosms for at least 120 days. In contrast, soil with 1.5% NaCl affected their culturability at day 90 and their viability at day 120. Our results suggested that a low salinity and iron may influence the survival of B. pseudomallei and its ability to change from a rod-like to coccoid form. The morphological changes of B. pseudomallei cells may be advantageous for their persistence in the environment and may increase the risk of their transmission to humans. PMID:26324731

Transfers and transformations of zinc in flow-through wetland microcosms.

PubMed

Gillespie, W B; Hawkins, W B; Rodgers, J H; Cano, M L; Dorn, P B

1999-06-01

Two microcosm-scale wetlands (570-liter containers) were integratively designed and constructed to investigate transfers and transformations of zinc associated with an aqueous matrix, and to provide future design parameters for pilot-scale constructed wetlands. The fundamental design of these wetland microcosms was based on biogeochemical principles regulating fate and transformations of zinc (pH, redox, etc.). Each wetland consisted of a 45-cm hydrosoil depth inundated with 25 cm of water, and planted with Scirpus californicus. Zinc ( approximately 2 mg/liter) as ZnCl2 was amended to each wetland for 62 days. Individual wetland hydraulic retention times (HRT) were approximately 24 h. Total recoverable zinc was measured daily in microcosm inflow and outflows, and zinc concentrations in hydrosoil and S. californicus tissue were measured pre- and post-treatment. Ceriodaphnia dubia and Pimephales promelas7-day aqueous toxicity tests were performed on wetland inflows and outflows, and Hyalella azteca whole sediment toxicity tests (10-day) were performed pre- and post-treatment. Approximately 75% of total recoverable zinc was transferred from the water column. Toxicity decreased from inflow to outflow based on 7-day C. dubia tests, and survival of H. azteca in hydrosoil was >80%. Data illustrate the ability of integratively designed wetlands to transfer and sequester zinc from the water column while concomitantly decreasing associated toxicity. Copyright 1999 Academic Press.

Emissions of NO and N2O in wetland microcosms for swine wastewater treatment.

PubMed

Zhang, Shunan; Liu, Feng; Xiao, Runlin; Li, Yong; Zhou, Juan; Wu, Jinshui

2015-12-01

Nitric oxide (NO) and nitrous oxide (N2O) emitted from wetland systems contribute an important proportion to the global warming effect. In this study, four wetland microcosms vegetated with Myriophyllum elatinoides (WM), Alternanthera philoxeroides (WA), Eichhornia crassipes (WE), or without vegetation (NW) were compared to investigate the emissions of NO and N2O during nitrogen (N) removal process when treating swine wastewater. After 30-day incubation, TN removal rates of 96.4, 74.2, 97.2, and 47.3 % were observed for the WM, WA, WE, and NW microcosms, respectively. Yet, no significant difference was observed in WM and WE (p > 0.05). The average NO and N2O emissions in WE was significantly higher than those in WM, WA, and NW (p < 0.05). In addition, the emission of N2O in WE accounted for 2.10 % of initial TN load and 2.17 % of the total amount of TN removal, compared with less than 1 % in the other microcosms. These findings indicate that wetland vegetated with M. elatinoides may be an optimal system for swine wastewater treatment, based on its higher removal of N and lower emissions of NO and N2O.

Effects of Eichhornia crassipes and Ceratophyllum demersum on Soil and Water Environments and Nutrient Removal in Wetland Microcosms.

PubMed

Sung, Kijune; Lee, Geun-Joo; Munster, Clyde

2015-01-01

Wetland plants are important components that influence the biogeochemistry of wetland ecosystems. Therefore, remediation performance in wetlands can differ depending on the growth forms of plants. In this study, the effects of Eichhornia crassipes (floating plant) and Ceratophyllum demersum (submerged plant) on the wetland soil and water environments were investigated using a microcosm study with simulated hydrology of retention-type wetlands between rainfall events. The C. demersum microcosm (SP) showed the fastest recovery with a diel fluctuation pattern of dissolved oxygen, pH, and oxidation-reduction potential (ORP) from the impacts of nutrient inflow. Moreover, SP exhibited the lowest decrease in sediment ORP, the highest dehydrogenase activity, and more organic forms of nitrogen and phosphorus. E. crassipes microcosms exhibited the lowest water temperature, and efficiently controlled algae. In the presence of plants, the total nitrogen and phosphorus concentrations in water rapidly decreased, and the composition of organic and inorganic nutrient forms was altered along with a decrease in concentration. The results indicate that wetland plants help retain nutrients in the system, but the effects varied based on the wetland plant growth forms.

Control of pore geometry in soil microcosms and its effect on the growth and spread of Pseudomonas and Bacillus sp.

NASA Astrophysics Data System (ADS)

Otten, Wilfred; Juyal, Archana; Eickhorst, Thilo; Falconer, Ruth; Spiers, Andrew; Baveye, Philippe

2017-04-01

The way micro-organisms access C and interact with each other in heterogeneous environments is key to our understanding of soil processes. Growth and mobility of bacteria is crucial aspect of these processes in particular how this is affected by complicated pathways of water and air-filled pores. Simplified experimental systems, often referred to with the term microcosms, have played a central role in the development of modern ecological thinking ranging from competitive exclusion to examination of spatial resources and competitive mechanisms, with important model driven insights to the field. However, in the majority of cases these do not include detailed description of the soil physical conditions and hence there is still little insight in how soil structure affects these processes. Recent advances in the use of Xray CT now allow for a different approach to this as we can obtain quantitative insight in to the pathways of interaction and how these are controlled in microcosms. In the current presentation we therefor ask the following questions: - To what extent can we control the pore geometry in microcosm studies through manipulation of common variables such as density and aggregate size? Are replicated microcosms really replicated at the microscale? - What is the effect of pore geometry on the growth dynamics of bacteria following introduction into soil? - What is the effect of pore geometry on the rate and extent of spread of bacteria in soil? We focus on Pseudomonas sp. and Bacillus sp. Both species are abundantly present in the rhizosphere and bulk-soil, frequently studied for their growth promoting ability, yet there is still very little knowledge available on how the growth and spread is affected by soil physical conditions such as pore geometry and wetness. We show how pore geometry, connectivity and interface areas are affected by the way soil is packed into microcosms and how this affects growth and spread of both species. We emphasize that microscopic

ARSENIC MOBILIZATION FROM SEDIMENTS IN MICROCOSMS UNDER SULFATE REDUCTION

PubMed Central

Sun, Jing; Quicksall, Andrew N.; Chillrud, Steven N.; Mailloux, Brian J.; Bostick, Benjamin C.

2016-01-01

Arsenic is often assumed to be immobile in sulfidic environments. Here, laboratory-scale microcosms were conducted to investigate whether microbial sulfate reduction could control dissolved arsenic concentrations sufficiently for use in groundwater remediation. Sediments from the Vineland Superfund site and the Coeur d'Alene mining district were amended with different combination of lactate and sulfate and incubated for 30 to 40 days. In general, sulfate reduction in Vineland sediments resulted in transient and incomplete arsenic removal, or arsenic release from sediments. Sulfate reduction in the Coeur d'Alene sediments was more effective at removing arsenic from solution than the Vineland sediments, probably by arsenic substitution and adsorption within iron sulfides. X-ray absorption spectroscopy indicated that the Vineland sediments initially contained abundant reactive ferrihydrite, and underwent extensive sulfur cycling during incubation. As a result, arsenic in the Vineland sediments could not be effectively converted to immobile arsenic-bearing sulfides, but instead a part of the arsenic was probably converted to soluble thioarsenates. These results suggest that coupling between the iron and sulfur redox cycles must be fully understood for in situ arsenic immobilization by sulfate reduction to be successful. PMID:27037658

The stability and fate of synthesized zero-valent iron nanoparticles in freshwater microcosm system.

PubMed

Kumar, Deepak; Parashar, Abhinav; Chandrasekaran, Natarajan; Mukherjee, Amitava

2017-07-01

Zero-valent iron nanoparticles are used for the degradation of organic compounds and the immobilization of metals and metalloids. The lack of information on the effect of nZVI in freshwater system necessitated the risk assessment of zero-valent iron nanoparticles in lake water environment. The present study deals with the stability and fate of synthesized zero-valent iron nanoparticles in the upper and lower layers of freshwater microcosm system at a concentration of 1000 mg L -1 . The study was divided into two different exposure periods: short-term exposure, up to 24 h after the introduction of nanoparticles, and long-term exposure period up to 180 days (4416 h). Aggregation kinetics of nZVI in freshwater microcosm was studied by measuring the mean hydrodynamic size of the nanoparticles with respect to time. A gradual increase in the particle size with time was observed up to 14 h. The algal population and total chlorophyll content declined for the short exposure period, i.e., 2-24 h, while in the case of longer exposure period, i.e., 24 h to 180 days (4416 h), a gradual increase of both the algal population and total chlorophyll was noted. Five different physico-chemical parameters such as pH, temperature, conductivity, salinity, and total dissolved solids were recorded for 180 days (6 calendar months). The study suggested that the nanoscale zero-valent iron did not exhibit significant toxicity at an exposure concentration of 1000 mg L -1 on the resident algal population in the microcosm system over the longer exposure period tested.

Population dynamics of transgenic strain Escherichia coli Z905/pPHL7 in freshwater and saline lake water microcosms with differing microbial community structures

NASA Astrophysics Data System (ADS)

Popova, L. Yu.; Kargatova, T. V.; Ganusova, E. E.; Lobova, T. I.; Boyandin, A. N.; Mogilnaya, O. A.; Pechurkin, N. S.

Populations of Escherichia coli Z905/pPHL7, a transgenic microorganism, were heterogenic in the expression of plasmid genes when adapting to the conditions of water microcosms of various mineralization levels and structure of microbial community. This TM has formed two subpopulations (ampicillin-resistant and ampicillin-sensitive) in every microcosm. Irrespective of mineralization level of a microcosm, when E. coli Z905/pPHL7 alone was introduced, the ampicillin-resistant subpopulation prevailed, while introduction of the TM together with indigenous bacteria led to the dominance of the ampicillin-sensitive subpopulation. A high level of lux gene expression maintained longer in the freshwater microcosms than in sterile saline lake water microcosms. A horizontal gene transfer has been revealed between the jointly introduced TM and Micrococcus sp. 9/pSH1 in microcosms with the Lake Shira sterile water.

Liquid based formulations of bacteriophages for the management of waterborne bacterial pathogens in water microcosms.

PubMed

Ahiwale, Sangeeta; Tagunde, Sujata; Khopkar, Sushama; Karni, Mrudula; Gajbhiye, Milind; Kapadnis, Balasaheb

2013-11-01

Water resources are contaminated by life-threatening multidrug resistant pathogenic bacteria. Unfortunately, these pathogenic bacteria do not respond to the traditional water purification methods. Therefore, there is a need of environmentally friendly strategies to overcome the problems associated with the antimicrobial resistant bacterial pathogens. In the present study, highly potent lytic phages against multidrug-resistant Salmonella enterica serovar Paratyphi B, Pseudomonas aeruginosa and Klebsiella pneumoniae were isolated from the Pavana river water. They belonged to the Podoviridae and Siphoviridae families. These phages were purified and enriched in the laboratory. Monovalent formulations of phiSPB, BVPaP-3 and KPP phages were prepared in three different liquids viz., phage broth, saline and distilled water. The phages were stable for almost 8-10 months in the phage broth at 4 degrees C. The stability of the phages in saline and distilled water was 5-6 months at 4 degrees C. All of the phages were stable only for 4-6 months in the phage broth at 30 degrees C. The monovalent phage formulation of psiSPB was applied at MOI < 1, as disinfectant against an exponential and stationary phase cells of Salmonella enterica serovar Paratyphi B in various water microcosms. The results indicated that there was almost 80 % reduction in the log phase cells of Salmonella serovar Paratyphi B in 24 h. In stationary phase cells, the reduction was comparatively less within same period. At the same time, there was concomitant increase in the phage population by 80% in all the microcosms indicating that psiSPB phage is highly potent in killing pathogen in water. Results strongly support that the formulation of psiSPB in the phage broth in monovalent form could be used as an effective biological disinfectant for preventing transmission of water-borne bacterial pathogens, including antimicrobial resistant ones.

Microbial community characterization and functional gene quantification in RDX-degrading microcosms derived from sediment and groundwater at two naval sites.

PubMed

Wilson, Fernanda Paes; Cupples, Alison M

2016-08-01

The explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has long been recognized as a problematic environmental pollutant, and efforts to remediate contaminated soils, sediments, and groundwater have been going on for decades. In recent years, much interest has focused on using bioremediation to clean up these sites. The current study investigated the microorganisms (16S rRNA genes, Illumina) and functional genes (xenA, xenB, and xplA) linked to RDX biodegradation in microcosms composed of sediment or groundwater from two Navy sites. For this, experiments included sediment samples from three depths (5 to 30 ft) from two wells located in one Navy site. In addition, the groundwater upstream and downstream of an emulsified oil biobarrier was examined from another Navy site. Further, for the groundwater experiments, the effect of glucose addition was explored. For the sediment experiments, the most enriched phylotypes during RDX degradation varied over time, by depth and well locations. However, several trends were noted, including the enrichment of Pseudomonas, Rhodococcus, Arthrobacter, and Sporolactobacillus in the sediment microcosms. For the groundwater-based experiments, Pseudomonas, unclassified Rhodocyclaceae, Sphingomonas, and Rhodococcus were also highly abundant during RDX degradation. The abundance of both xplA and xenA significantly increased during RDX degradation compared to the control microcosms for many treatments (both groundwater and sediment microcosms). In a limited number of microcosms, the copy number of the xenB gene increased. Phylotype data were correlated with functional gene data to highlight potentially important biomarkers for RDX biodegradation at these two Navy sites.

Increases of Chamber Height and Base Diameter Have Contrasting Effects on Grazing Rate of Two Cladoceran Species: Implications for Microcosm Studies.

PubMed

Pan, Ying; Zhang, Yunshu; Peng, Yan; Zhao, Qinghua; Sun, Shucun

2015-01-01

Aquatic microcosm studies often increase either chamber height or base diameter (to increase water volume) to test spatial ecology theories such as "scale" effects on ecological processes, but it is unclear whether the increase of chamber height or base diameter have the same effect on the processes, i.e., whether the effect of the shape of three-dimensional spaces is significant. We orthogonally manipulated chamber height and base diameter and determined swimming activity, average swimming velocity and grazing rates of the cladocerans Daphnia magna and Moina micrura (on two algae Scenedesmus quadricauda and Chlorella vulgaris; leading to four aquatic algae-cladoceran systems in total) under different microcosm conditions. Across all the four aquatic systems, increasing chamber height at a given base diameter significantly decreased the duration and velocity of horizontal swimming, and it tended to increase the duration but decrease the velocity of vertical swimming. These collectively led to decreases in both average swimming velocity and grazing rate of the cladocerans in the tall chambers (at a given base diameter), in accordance with the positive relationship between average swimming velocity and grazing rate. In contrast, an increase of base diameter at a given chamber height showed contrasting effects on the above parameters. Consistently, at a given chamber volume increasing ratio of chamber height to base diameter decreased the average swimming velocity and grazing rate across all the aquatic systems. In general, increasing chamber depth and base diameter may exert contrasting effects on zooplankton behavior and thus phytoplankton-zooplankton interactions. We suggest that spatial shape plays an important role in determining ecological process and thus should be considered in a theoretical framework of spatial ecology and also the physical setting of aquatic microcosm experiments.

Increases of Chamber Height and Base Diameter Have Contrasting Effects on Grazing Rate of Two Cladoceran Species: Implications for Microcosm Studies

PubMed Central

Pan, Ying; Zhang, Yunshu; Peng, Yan; Zhao, Qinghua; Sun, Shucun

2015-01-01

Aquatic microcosm studies often increase either chamber height or base diameter (to increase water volume) to test spatial ecology theories such as “scale” effects on ecological processes, but it is unclear whether the increase of chamber height or base diameter have the same effect on the processes, i.e., whether the effect of the shape of three-dimensional spaces is significant. We orthogonally manipulated chamber height and base diameter and determined swimming activity, average swimming velocity and grazing rates of the cladocerans Daphnia magna and Moina micrura (on two algae Scenedesmus quadricauda and Chlorella vulgaris; leading to four aquatic algae-cladoceran systems in total) under different microcosm conditions. Across all the four aquatic systems, increasing chamber height at a given base diameter significantly decreased the duration and velocity of horizontal swimming, and it tended to increase the duration but decrease the velocity of vertical swimming. These collectively led to decreases in both average swimming velocity and grazing rate of the cladocerans in the tall chambers (at a given base diameter), in accordance with the positive relationship between average swimming velocity and grazing rate. In contrast, an increase of base diameter at a given chamber height showed contrasting effects on the above parameters. Consistently, at a given chamber volume increasing ratio of chamber height to base diameter decreased the average swimming velocity and grazing rate across all the aquatic systems. In general, increasing chamber depth and base diameter may exert contrasting effects on zooplankton behavior and thus phytoplankton-zooplankton interactions. We suggest that spatial shape plays an important role in determining ecological process and thus should be considered in a theoretical framework of spatial ecology and also the physical setting of aquatic microcosm experiments. PMID:26273836

Population dynamics of transgenic strain Escherichia coli Z905/pPHL7 in freshwater and saline lake water microcosms with differing microbial community structures

NASA Technical Reports Server (NTRS)

Popova, L. Yu; Kargatova, T. V.; Ganusova, E. E.; Lobova, T. I.; Boyandin, A. N.; Mogilnaya, O. A.; Pechurkin, N. S.

2005-01-01

Populations of Escherichia coli Z905/pPHL7, a transgenic microorganism, were heterogenic in the expression of plasmid genes when adapting to the conditions of water microcosms of various mineralization levels and structure of microbial community. This TM has formed two subpopulations (ampicillin-resistant and ampicillin-sensitive) in every microcosm. Irrespective of mineralization level of a microcosm, when E. coli Z905/pPHL7 alone was introduced, the ampicillin-resistant subpopulation prevailed, while introduction of the TM together with indigenous bacteria led to the dominance of the ampicillin-sensitive subpopulation. A high level of lux gene expression maintained longer in the freshwater microcosms than in sterile saline lake water microcosms. A horizontal gene transfer has been revealed between the jointly introduced TM and Micrococcus sp. 9/pSH1 in microcosms with the Lake Shira sterile water. c2005 COSPAR. Published by Elsevier Ltd. All rights reserved.

The in vitro effect of Antimicrobial Photodynamic Therapy on dental microcosm biofilms from partially erupted permanent molars: A pilot study.

PubMed

de Oliveira, Fabiana Sodré; Cruvinel, Thiago; Cusicanqui Méndez, Daniela Alejandra; Dionísio, Evandro José; Rios, Daniela; Machado, Maria Aparecida Andrade Moreira

2018-03-01

Antimicrobial Photodynamic Therapy (aPDT) could enhance the prevention of dental caries lesions in pits and fissures of partially erupted molars, by killing microorganisms from complex dental biofilms. This pilot study aimed to evaluate the effect of Antimicrobial Photodynamic Therapy (aPDT) on the viability of specific microorganism groups of dental microcosm biofilms from occlusal surfaces of first permanent molars in eruption. Dental microcosm biofilms grown on bovine enamel blocks, from dental plaque collected on occlusal surfaces of a partially erupted lower right first permanent molar, with McBain medium plus 1% sucrose in anaerobic condition at 37 °C for 72 h. The experiments were performed in eight groups: L-P- = no treatment (control), L18.75P- = 18.75 J/cm 2 LED, L37.5P- = 37.5 J/cm 2 LED, L75P- = 75 J/cm 2 LED, L-P+ = 200 mM TBO, L18.75P+ = 200 mM TBO + 18.75 J/cm 2 LED, L37.5P+ = 200 mM TBO + 37.5 J/cm 2 LED, and L75P+ = 200 mM TBO + 75 J/cm 2 LED. The counts of total microorganisms, total streptococci and mutans streptococci were determined on selective media agar plates by colony-forming units per mL. The log-transformed counts were analyzed by Kruskal-Wallis and post-hoc Dunn's test (P < 0.05). The counts of all microorganisms treated in the group L75P+ were statistically lower than those treated in L-P-. The aPDT promoted a significant reduction of microorganisms, with a trend of dose-dependent effect. TBO-mediated aPDT was effective in reducing the viability of specific microbial groups in dental microcosm biofilms originated from occlusal of permanent molars in eruption. Copyright © 2017 Elsevier B.V. All rights reserved.

Microbial Community Phylogenetic and Functional Succession in Chromium-Reducing Aquifer-Derived Microcosms

NASA Astrophysics Data System (ADS)

Brodie, E. L.; Beller, H. R.; Goldfarb, K. C.; Han, R.; Santee, C. A.

2009-12-01

In situ reductive immobilization, whereby highly soluble Cr(VI) species are reduced to poorly soluble Cr(III) species, is a favored approach for remediating Cr-contaminated groundwater. How microbial populations respond phylogenetically and functionally to the injection of an organic electron donor to stimulate Cr(VI) reduction is unclear, as are the relative contributions of direct enzymatic Cr(VI) reduction versus indirect (e.g. sulfide-mediated) reduction. In this study, we inoculated anaerobic microcosms with groundwater from the Cr-contaminated Hanford 100H site (WA) and supplemented them with lactate and the electron acceptors nitrate, sulfate, and amorphous ferric oxyhydroxide. The microcosms progressed successively through nitrate-reducing, sulfate-reducing, and Fe(III)-reducing conditions, and after a second nitrate amendment, nitrate-dependent Fe(II)-oxidizing conditions. Cr(VI) reduction occurred during both the denitrification and the sulfate/iron reduction phases. DNA and RNA were harvested during each major biogeochemical phase and were subjected to PhyloChip analysis, qPCR, and transcript sequencing. Bacterial community succession followed a trajectory related to the sequential use of electron acceptors. During denitrification, bacterial communities were enriched in known denitrifiers within the Beta- and Gamma-proteobacteria and became phylogenetically clustered. Fermenters became enriched following nitrate reduction, preceding both iron and sulfate reduction. Iron reduction was stoichiometrically related to the formation of hydrogen sulfide and, although iron reducers were detected during this phase, their iron-reducing activity was not confirmed. Following the depletion of lactate and sulfate, iron reduction rates decreased and acetate and propionate concentrations stabilized, indicating a marginal contribution of acetate-coupled iron reduction. Rapid Fe(II) oxidation occurred following the nitrate amendment with a concomitant reduction of nitrate

STIMULATION OF THE REDUCTIVE DECHLORINATION OF TETRACHLOROETHENE IN ANAEROBIC AQUIFER MICROCOSMS BY THE ADDITION OF TOLUENE

EPA Science Inventory

In this study, the biologically mediated interactions of toluene and PCE under anaerobic conditions were investigated by using microcosms constructed with aquifer solids from an area that was exposed to both alkylbenzenes and chlorinated ethenes at the U.S. Coast Guard Air Statio...

Accelerated biodegradation of BPA in water-sediment microcosms with Bacillus sp. GZB and the associated bacterial community structure.

PubMed

Xiong, Jukun; An, Taicheng; Li, Guiying; Peng, Ping'an

2017-10-01

Bisphenol A (BPA) is a synthetic chemical primarily used to produce polycarbonate plastics and epoxy resins. Significant industrial and consumer's consumption of BPA-containing products has contributed to extensive contamination in different environmental matrices. In this study, microcosms bioaugmented with Bacillus sp. GZB were constructed to investigate BPA biodegradation, identify the main bacterial community, and evaluate bacterial community responses in the microcosms. Under aerobic conditions, BPA was quickly depleted as a result of bioaugmentation with Bacillus sp. GZB in water-sediment contaminated with pollutants. The pollutants used were generally associated with the electronic wastes (mobile phones, computers, televisions) dismantling process. Adding BPA affected the bacterial community composition in the water-sediment. Furthermore, BPA biodegradation was enhanced by adding electron donors/co-substrates: humic acid, NaCl, glucose, and yeast extract. Metagenomic analysis of the total 16S rRNA genes from the BPA-degrading microcosms with bioaugmentation illustrated that the genera Bacillus, Thiobacillus, Phenylobacterium, and Cloacibacterium were dominant after a 7-week incubation period. A consortium of microorganisms from different bacterial genera may be involved in BPA biodegradation in electronic waste contaminated water-sediment. This study provides new insights about BPA bioaugmentation and bacterial ecology in the BPA-degrading environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Toxic effects of isoproturon on periphyton communities a microcosm study

NASA Astrophysics Data System (ADS)

Schmitt-Jansen, Mechthild; Altenburger, Rolf

2005-02-01

Coastal and estuarine ecosystems are increasingly exposed to herbicide contamination. To study the potential risks of these pollutants, the establishment of periphyton communities under exposure of a concentration series of isoproturon in a range of 0.0024-0.312 mg L -1 was investigated in a microcosm study. After two weeks of growth, chronic effects on biomass development, measured as Chl a fluorescence, taxonomic composition and photosynthetic capacity of PS II of attached microalgae were analysed using a pulse-amplitude modulated (PAM) fluorescence-based method. Algal classes were differentiated according to their pigment systems using four excitation wavelengths. Biomass remained constant up to pre-exposure concentrations of 0.02 mg L -1 isoproturon but decreased within one order of magnitude at the highest test concentration. Algal classes shifted from diatoms to chlorophytes at pre-exposure concentrations of 0.02-0.39 mg L -1. Community structure of diatoms representing the dominant group of attached algae at lower test concentrations was studied by microscopic analysis revealing that species numbers were highest at lowest test concentrations as compared to controls. At higher test concentrations Navicula halophila dominated with 89% of the diatom biomass but was abnormally shaped. Pollution-induced community tolerance (PICT) of periphyton to isoproturon was determined by short-term inhibition tests of photosynthesis. Pre-exposed communities increased their effect concentrations (EC 50) up to threefold within the 0.039 mg L -1 pre-treatment. Our results suggest that attached microalgal communities have a high potential of tolerance development to isoproturon at lower levels of contamination due to the replacement of sensitive species by more tolerant algae, although these species seemed to be affected too. We conclude that herbicide concentrations in river basins, estuaries or coastal zones may change community structure and primary production of

Experimental microcosm study of the effects of Deepwater Horizon MC-252 oil on the geochemistry and microbiology of Gulf Coast sediment

NASA Astrophysics Data System (ADS)

Donahoe, R. J.; Bej, A.; Raulerson, A.; Rentschler, E. K.

2011-12-01

Microcosm experiments were conducted to examine the impact of oil contamination on Gulf Coast sediment geochemistry and microbial population dynamics. Coastal sediment and seawater were collected from a salt marsh at Bayou la Batre, Alabama, which was not severely impacted by the BP Deepwater Horizon accident of April 2010. Sediment/seawater microcosms were set up in glass jars combusted for 5 hours at 450 degrees C. Non-sterile microcosms spiked with 500 ppm of MC-252 oil were sacrificed in duplicate at various time intervals over a 14 day period to establish a data time series. Sterile controls with and without oil and a non-sterile control without oil were sacrificed in duplicate at 14 days for comparison with the time-series experiments. Solid and aqueous phases were separated by centrifugation and prepared for analysis. Sediment mineralogy was determined using X-ray diffraction and acid-extractable sediment chemistry determined using EPA Method 3051A and ICP-OES analysis. The aqueous phase chemistry was analyzed by ICP-OES and ion chromatography. The mineralogy of the salt marsh sediment is predominantly quartz, but includes reactive phases such as clays (smectite, illite), feldspar, and iron oxide. Iron-bearing clays and iron oxides can serve as electron acceptors for the growth of Fe(III)-reducing bacteria. Microwave digestions of the microcosm substrate samples were performed in triplicate and show no significant variation in major element chemistry over the course of the two week experiment, suggesting that observed temporal trends in aqueous geochemistry may be due to ion exchange processes, rather than mineral dissolution reactions. Microcosm substrate trace element data which indicate possible differences with time are being analyzed for statistical significance. Analysis of aqueous solution geochemistry reveals several interesting temporal trends. Iron and manganese were released to solution after 2 days, suggesting the presence of facultative

Radiation-induced impacts on the degradation of 2,4-D and the microbial population in soil microcosms.

PubMed

Niedrée, Bastian; Vereecken, Harry; Burauel, Peter

2013-01-01

In a soil microcosm experiment, the influence of low-level (137)Cs and (90)Sr contamination on the degradation of (14)C-ring-labeled 2,4-dichlorophenoxyacetic acid (2,4-D) was studied. Two differently treated soils (one native soil and one soil sterilized and reinoculated with a biotic soil aliquot) were artificially contaminated with various concentrations of (137)Cs and (90)Sr as nitrate salts. The cumulative doses increased up to 4 Gy for 30 days of incubation in soil microcosms. Changes in microbial community structure were observed with help of the denaturing gradient gel electrophoresis (DGGE). A radiation-induced impact appeared only in the microcosms treated with 30 times the maximum contamination appearing in the exclusion zone around reactor 4 in Chernobyl. In contrast to the less contaminated soils, the mineralization of 2,4-D was delayed for 4 days before it recovered. Slight shifts in the microbial communities could be traced to radiation effects. However, other parameters had a major impact on mineralization and community structure. Thus the sterilization and reinoculation and, of course, application of the 2,4-D were predominantly reflected in the (14)CO(2) emissions and the DGGE gel patterns. Copyright © 2012 Elsevier Ltd. All rights reserved.

Biotic and abiotic interactions in aquatic microcosms determine fate and toxicity of Ag nanoparticles. Part 1. Aggregation and dissolution.

PubMed

Unrine, Jason M; Colman, Benjamin P; Bone, Audrey J; Gondikas, Andreas P; Matson, Cole W

2012-07-03

To better understand their fate and toxicity in aquatic environments, we compared the aggregation and dissolution behavior of gum arabic (GA) and polyvinylpyrrolidone (PVP) coated Ag nanoparticles (NPs) in aquatic microcosms. There were four microcosm types: surface water; water and sediment; water and aquatic plants; or water, sediment, and aquatic plants. Dissolution and aggregation behavior of AgNPs were examined using ultracentrifugation, ultrafiltration, and asymmetrical flow field flow fractionation coupled to ultraviolet-visible spectroscopy, dynamic and static laser light scattering, and inductively coupled plasma mass spectrometry. Plants released dissolved organic matter (DOM) into the water column either through active or passive processes in response to Ag exposure. This organic matter fraction readily bound Ag ions. The plant-derived DOM had the effect of stabilizing PVP-AgNPs as primary particles, but caused GA-AgNPs to be removed from the water column, likely by dissolution and binding of released Ag ions on sediment and plant surfaces. The destabilization of the GA-AgNPs also corresponded with X-ray absorption near edge spectroscopy results which suggest that 22-28% of the particulate Ag was associated with thiols and 5-14% was present as oxides. The results highlight the potential complexities of nanomaterial behavior in response to biotic and abiotic modifications in ecosystems, and may help to explain differences in toxicity of Ag observed in realistic exposure media compared to simplified laboratory exposures.

Effects of imidacloprid on the ecology of sub-tropical freshwater microcosms.

PubMed

Sumon, Kizar Ahmed; Ritika, Afifat Khanam; Peeters, Edwin T H M; Rashid, Harunur; Bosma, Roel H; Rahman, Md Shahidur; Fatema, Mst Kaniz; Van den Brink, Paul J

2018-05-01

The neonicotinoid insecticide imidacloprid is used in Bangladesh for a variety of crop protection purposes. Imidacloprid may contaminate aquatic ecosystems via spray drift, surface runoff and ground water leaching. The present study aimed at assessing the fate and effects of imidacloprid on structural (phytoplankton, zooplankton, macroinvertebrates and periphyton) and functional (organic matter decomposition) endpoints of freshwater, sub-tropical ecosystems in Bangladesh. Imidacloprid was applied weekly to 16 freshwater microcosms (PVC tanks containing 400 L de-chlorinated tap water) at nominal concentrations of 0, 30, 300, 3000 ng/L over a period of 4 weeks. Results indicated that imidacloprid concentrations from the microcosm water column declined rapidly. Univariate and multivariate analysis showed significant effects of imidacloprid on the zooplankton and macroinvertebrate community, some individual phytoplankton taxa, and water quality variables (i.e. DO, alkalinity, ammonia and nitrate), with Cloeon sp., Diaptomus sp. and Keratella sp. being the most affected species, i.e. showing lower abundance values in all treatments compared to the control. The observed high sensitivity of Cloeon sp. and Diaptomus sp. was confirmed by the results of single species tests. No significant effects were observed on the species composition of the phytoplankton, periphyton biomass and organic matter decomposition for any of the sampling days. Our study indicates that (sub-)tropical aquatic ecosystems can be much more sensitive to imidacloprid compared to temperate ones. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Dental plaque microcosm response to bonding agents containing quaternary ammonium methacrylates with different chain lengths and charge densities

PubMed Central

Zhou, Han; Li, Fang; Weir, Michael D.; Xu, Hockin H.K.

2013-01-01

Objectives Antibacterial bonding agents are promising to combat bacteria and caries at tooth-restoration margins. The objectives of this study were to incorporate new quaternary ammonium methacrylates (QAMs) to bonding agent and determine the effects of alkyl chain length (CL) and quaternary amine charge density on dental plaque microcosm bacteria response for the first time. Methods Six QAMs were synthesized with CL = 3, 6, 9, 12, 16, 18. Each QAM was incorporated into Scotchbond Multi-purpose (SBMP). To determine the charge density effect, dimethylaminododecyl methacrylate (DMAHDM, CL = 16) was mixed into SBMP at mass fraction = 0%, 2.5%, 5%, 7.5%, 10%. Charge density was measured using a fluorescein dye method. Dental plaque microcosm using saliva from ten donors was tested. Bacteria were inoculated on resins. Early-attachment was tested at 4 hours. Biofilm colony-forming units (CFU) were measured at 2 days. Results Incorporating QAMs into SBMP reduced bacteria early-attachment. Microcosm biofilm CFU for CL = 16 was 4 log lower than SBMP control. Charge density of bonding agent increased with DMAHDM content. Bacteria early-attachment decreased with increasing charge density. Biofilm CFU at 10% DMAHDM was reduced by 4 log. The killing effect was similarly-strong against total microorganisms, total streptococci, and mutans streptococci. Conclusions Increasing alkyl chain length and charge density of bonding agent was shown for the first time to decrease microcosm bacteria attachment and reduce biofilm CFU by 4 orders of magnitude. Novel antibacterial resins with tailored chain length and charge density are promising for wide applications in bonding, cements, sealants and composites to inhibit biofilms and caries. PMID:23948394

Dental plaque microcosm response to bonding agents containing quaternary ammonium methacrylates with different chain lengths and charge densities.

PubMed

Zhou, Han; Li, Fang; Weir, Michael D; Xu, Hockin H K

2013-11-01

Antibacterial bonding agents are promising to combat bacteria and caries at tooth-restoration margins. The objectives of this study were to incorporate new quaternary ammonium methacrylates (QAMs) to bonding agent and determine the effects of alkyl chain length (CL) and quaternary amine charge density on dental plaque microcosm bacteria response for the first time. Six QAMs were synthesized with CL=3, 6, 9, 12, 16, 18. Each QAM was incorporated into Scotchbond multi-purpose (SBMP). To determine the charge density effect, dimethylaminododecyl methacrylate (DMAHDM, CL=16) was mixed into SBMP at mass fraction=0%, 2.5%, 5%, 7.5%, 10%. Charge density was measured using a fluorescein dye method. Dental plaque microcosm using saliva from ten donors was tested. Bacteria were inoculated on resins. Early-attachment was tested at 4h. Biofilm colony-forming units (CFU) were measured at 2 days. Incorporating QAMs into SBMP reduced bacteria early-attachment. Microcosm biofilm CFU for CL=16 was 4 log lower than SBMP control. Charge density of bonding agent increased with DMAHDM content. Bacteria early-attachment decreased with increasing charge density. Biofilm CFU at 10% DMAHDM was reduced by 4 log. The killing effect was similarly-strong against total microorganisms, total streptococci, and mutans streptococci. Increasing alkyl chain length and charge density of bonding agent was shown for the first time to decrease microcosm bacteria attachment and reduce biofilm CFU by 4 orders of magnitude. Novel antibacterial resins with tailored chain length and charge density are promising for wide applications in bonding, cements, sealants and composites to inhibit biofilms and caries. Copyright © 2013 Elsevier Ltd. All rights reserved.

Biological denitrification in marine aquaculture systems: A multiple electron donor microcosm study.

PubMed

He, Qiaochong; Zhang, Dongqing; Main, Kevan; Feng, Chuanping; Ergas, Sarina J

2018-05-08

There is a lack of information on denitrification of saline wastewaters, such as those from marine recirculating aquaculture systems (RAS), ion exchange brines and wastewater in areas where sea water is used for toilet flushing. In this study, side-by-side microcosms were used to compare methanol, fish waste (FW), wood chips, elemental sulfur (S 0 ) and a combination of wood chips and sulfur for saline wastewater denitrification. The highest denitrification rate was obtained with methanol (23.4 g N/(m 3 ·d)), followed by FW (4.5 g N/(m 3 ·d)), S 0 (3.5 g N/(m 3 ·d)), eucalyptus mulch (2.6 g N/(m 3 ·d)), and eucalyptus mulch with sulfur (2.2 g N/(m 3 ·d)). Significant differences were observed in denitrification rate for different wood species (pine > oak ≫ eucalyptus) due to differences in readily biodegradable organic carbon released. A pine wood-sulfur heterotrophic-autotrophic denitrification (P-WSHAD) process provided a high denitrification rate (7.2-11.9 g N/(m 3 ·d)), with lower alkalinity consumption and sulfate generation than sulfur alone. Copyright © 2018 Elsevier Ltd. All rights reserved.

Inhibition of nitrate reduction by chromium (VI) in anaerobic soil microcosms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kourtev, P. S.; Nakatsu, C. H.; Konopka, Allan

2009-10-01

Chromium (VI) is often found as a co-contaminant at sites polluted with organic compounds. We used microcosms amended with glucose or protein, nitrate and increasing concentrations of chromium to study nitrate reduction in Cr(VI) polluted soils. Organic carbon stimulated bacterial activity, but the addition of Cr(VI) caused a lag and then slower rates 5 of CO2 accumulation. Nitrate reduction only occurred after Cr(VI) had been reduced. Bacterial activity was again inhibited when Cr(VI) was added a second time; thus not all Cr-sensitive bacteria were removed in the first phase. Glucose and protein selected for relatively similar bacterial communities, as assayedmore » by PCR-DGGE of the 16S rRNA gene; this selection was modified by the addition of 10 Cr(VI). Cr-resistant bacteria isolated from microcosms were closely related to members of Bacillus, Enterococcus and Propionibacterium sp. Our results indicate that carbon utilization and nitrate reduction in these soils in the presence of Cr(VI) are contingent upon the reduction of the added heavy metal by a limited subset of the bacterial community. The amount of Cr(VI) required to inhibit nitrate reduction was 10-fold less than for aerobic catabolism of the same 15 substrate. We hypothesize that the resistance level of a microbial process is directly related to the diversity of microbes capable of conducting it.« less

Inhibition of Biodegradation of Hydraulic Fracturing Compounds by Glutaraldehyde: Groundwater Column and Microcosm Experiments.

PubMed

Rogers, Jessica D; Ferrer, Imma; Tummings, Shantal S; Bielefeldt, Angela R; Ryan, Joseph N

2017-09-05

The rapid expansion of unconventional oil and gas development has raised concerns about the potential contamination of aquifers; however, the groundwater fate and transport of hydraulic fracturing fluid compounds and mixtures remains a significant data gap. Degradation kinetics of five hydraulic fracturing compounds (2-propanol, ethylene glycol, propargyl alcohol, 2-butoxyethanol, and 2-ethylhexanol) in the absence and presence of the biocide glutaraldehyde were investigated under a range of redox conditions using sediment-groundwater microcosms and flow-through columns. Microcosms were used to elucidate biodegradation inhibition at varying glutaraldehyde concentrations. In the absence of glutaraldehyde, half-lives ranged from 13 d to >93 d. Accurate mass spectrometry indicated that a trimer was the dominant aqueous-phase glutaraldehyde species. Microbial inhibition was observed at glutaraldehyde trimer concentrations as low as 5 mg L -1 , which demonstrated that the trimer retained some biocidal activity. For most of the compounds, biodegradation rates slowed with increasing glutaraldehyde concentrations. For many of the compounds, degradation was faster in the columns than the microcosms. Four compounds (2-propanol, ethylene glycol, propargyl alcohol, and 2-butoxyethanol) were found to be both mobile and persistent in groundwater under a range of redox conditions. The glutaraldehyde trimer and 2-ethylhexanol were more rapidly degraded, particularly under oxic conditions.

Microcosm investigation of growth and phytoremediation potential of Azolla japonica along nitrogen gradients.

PubMed

Park, Hun; Song, Uhram

2017-10-03

Although Azolla species are among the most promising plants for use in phytoremediation, more studies on their growth and nitrogen (N) uptake along the N gradients of growing media are required. In this study, N concentration-dependent growth in growing media and phosphorus (P) and N accumulation by Azolla japonica were studied by estimating direct N uptake from media by molybdenum-iron proteins. The doubling time of A. japonica was less than a week, regardless of the N concentration (0, 5, and 25 mg N/L) present in the growth media, indicating that this plant is suitable for remediation. Plants showed a high uptake of P, probably via plant-bacteria symbiosis, indicating their potential for effective P remediation. A. japonica also showed more than 4% N content regardless of the treatment and accumulated more than 40 mg of N per microcosm in 3 weeks. iron and molybdenum levels in plants were strongly associated with N fixation, and N uptake from media was estimated to be more than 25 mg per microcosm in 3 weeks, indicating that A. japonica has N remediation potential. As A. japonica is a rapidly growing plant, capable of efficient P and N remediation, it has great potential for use in phytoremediation of nutrient-enriched waters such as agricultural or urban wastewater and eutrophicated aquatic ecosystems.

EFFECTS OF MICROCOSM PREPARATION ON RATES OF TOLUENE BIODEGRADATION UNDER DENITRIFYING CONDITIONS

EPA Science Inventory

Microcosms were prepared with subsurface material from two aquifers to examine the effects of preparation methods on rates of toluene biodegradation under denitrifying conditions. In both cases, the data fit a zero-order kinetics plot. However, rates of removal were generally pro...

Dental plaque microcosm biofilm behavior on calcium phosphate nanocomposite with quaternary ammonium

PubMed Central

Cheng, Lei; Weir, Michael D.; Zhang, Ke; Wu, Eric; Xu, Sarah M.; Zhou, Xuedong; Xu, Hockin H. K.

2012-01-01

Objectives Half of dental restorations fail in 10 years, with secondary caries as the main reason. Calcium phosphate composites could remineralize tooth lesions. The objectives of this study were to: (1) Impart antibacterial activity to a composite with nanoparticles of amorphous calcium phosphate (NACP); and (2) investigate the effect of quaternary ammonium dimethacrylate (QADM) on mechanical and dental plaque microcosm biofilm properties for the first time. Methods The NACP and glass particles were filled into a dental resin that contained bis(2-methacryloyloxy-ethyl) dimethyl-ammonium bromide, the QADM. NACP nanocomposites containing 0%, 7%, 14%, and 17.5% of QADM by mass, respectively, were photo-cured. A commercial composite with no antibacterial activity was used as control. Mechanical properties were measured in three-point flexure. A human saliva microcosm model was used to grow biofilms on composites. Live/dead assay, metabolic activity, colony-forming unit (CFU) counts, and lactic acid production of biofilms on the composites were measured. Results Increasing QADM mass fraction monotonically reduced the biofilm viability, CFU and lactic acid. Biofilms on NACP nanocomposite with 17.5% QADM had metabolic activity that was 30% that on a commercial composite control (p<0.05). Total microorganisms, total streptococci, and mutans streptococci CFU counts (mean±sd; n=6) on composite control was 6-fold those on NACP+17.5% QADM nanocomposite. Composite control had long strings of cells with normal short-rod shapes, while some cells on NACP-QADM nanocomposites disintegrated into pieces. Adding QADM to NACP did not decrease the strength and elastic modulus, which matched (p>0.1) those of a commercial composite without Ca-PO4 or antibacterial activity. Significance A dental plaque microcosm model was used to evaluate the novel NACP-QADM nanocomposite. The nanocomposite greatly reduced the biofilm viability, metabolic activity and lactic acid, while its mechanical

Fate and Persistence of a Pathogenic NDM-1-Positive Escherichia coli Strain in Anaerobic and Aerobic Sludge Microcosms

PubMed Central

Mantilla-Calderon, David

2017-01-01

ABSTRACT The presence of emerging biological pollutants in treated wastewater effluents has gained attention due to increased interest in water reuse. To evaluate the effectiveness of the removal of such contaminants by the conventional wastewater treatment process, the fate and decay kinetics of NDM-1-positive Escherichia coli strain PI7 and its plasmid-encoded antibiotic resistance genes (ARGs) were assessed in microcosms of anaerobic and aerobic sludge. Results showed that E. coli PI7 decayed at a significantly lower rate under anaerobic conditions. Approximate half-lives were 32.4 ± 1.4 h and 5.9 ± 0.9 h in the anaerobic and aerobic microcosms, respectively. In the aerobic microcosms, after 72 h of operation, E. coli PI7 remained detectable, but no further decay was observed. Instead, 1 in every 10,000 E. coli cells was identified to be recalcitrant to decay and persist indefinitely in the sludge. ARGs associated with the E. coli PI7 strain were detected to have transferred to other native microorganisms in the sludge or were released to the liquid fraction upon host decay. Extracellular DNA quickly degraded in the liquid fraction of the aerobic sludge. In contrast, no DNA decay was detected in the anaerobic sludge water matrix throughout the 24-h sampling period. This study suggests an increased likelihood of environmental dispersion of ARGs associated with anaerobically treated wastewater effluents and highlights the potential importance of persister cells in the dissemination of E. coli in the environment during reuse events of treated wastewater. IMPORTANCE This study examines the decay kinetics of a pathogenic and antibiotic resistant strain of Escherichia coli in microcosms simulating biological treatment units of aerobic and anaerobic sludge. The results of this study point at a significantly prolonged persistence of the E. coli and the associated antibiotic resistance gene in the anaerobic sludge. However, horizontal transfer of the plasmid encoding

Fate and Persistence of a Pathogenic NDM-1-Positive Escherichia coli Strain in Anaerobic and Aerobic Sludge Microcosms.

PubMed

Mantilla-Calderon, David; Hong, Pei-Ying

2017-07-01

The presence of emerging biological pollutants in treated wastewater effluents has gained attention due to increased interest in water reuse. To evaluate the effectiveness of the removal of such contaminants by the conventional wastewater treatment process, the fate and decay kinetics of NDM-1-positive Escherichia coli strain PI7 and its plasmid-encoded antibiotic resistance genes (ARGs) were assessed in microcosms of anaerobic and aerobic sludge. Results showed that E. coli PI7 decayed at a significantly lower rate under anaerobic conditions. Approximate half-lives were 32.4 ± 1.4 h and 5.9 ± 0.9 h in the anaerobic and aerobic microcosms, respectively. In the aerobic microcosms, after 72 h of operation, E. coli PI7 remained detectable, but no further decay was observed. Instead, 1 in every 10,000 E. coli cells was identified to be recalcitrant to decay and persist indefinitely in the sludge. ARGs associated with the E. coli PI7 strain were detected to have transferred to other native microorganisms in the sludge or were released to the liquid fraction upon host decay. Extracellular DNA quickly degraded in the liquid fraction of the aerobic sludge. In contrast, no DNA decay was detected in the anaerobic sludge water matrix throughout the 24-h sampling period. This study suggests an increased likelihood of environmental dispersion of ARGs associated with anaerobically treated wastewater effluents and highlights the potential importance of persister cells in the dissemination of E. coli in the environment during reuse events of treated wastewater. IMPORTANCE This study examines the decay kinetics of a pathogenic and antibiotic resistant strain of Escherichia coli in microcosms simulating biological treatment units of aerobic and anaerobic sludge. The results of this study point at a significantly prolonged persistence of the E. coli and the associated antibiotic resistance gene in the anaerobic sludge. However, horizontal transfer of the plasmid encoding the

Transcriptomic responses of a simplified soil microcosm to a plant pathogen and its biocontrol agent reveal a complex reaction to harsh habitat.

PubMed

Perazzolli, Michele; Herrero, Noemí; Sterck, Lieven; Lenzi, Luisa; Pellegrini, Alberto; Puopolo, Gerardo; Van de Peer, Yves; Pertot, Ilaria

2016-10-27

Soil microorganisms are key determinants of soil fertility and plant health. Soil phytopathogenic fungi are one of the most important causes of crop losses worldwide. Microbial biocontrol agents have been extensively studied as alternatives for controlling phytopathogenic soil microorganisms, but molecular interactions between them have mainly been characterised in dual cultures, without taking into account the soil microbial community. We used an RNA sequencing approach to elucidate the molecular interplay of a soil microbial community in response to a plant pathogen and its biocontrol agent, in order to examine the molecular patterns activated by the microorganisms. A simplified soil microcosm containing 11 soil microorganisms was incubated with a plant root pathogen (Armillaria mellea) and its biocontrol agent (Trichoderma atroviride) for 24 h under controlled conditions. More than 46 million paired-end reads were obtained for each replicate and 28,309 differentially expressed genes were identified in total. Pathway analysis revealed complex adaptations of soil microorganisms to the harsh conditions of the soil matrix and to reciprocal microbial competition/cooperation relationships. Both the phytopathogen and its biocontrol agent were specifically recognised by the simplified soil microcosm: defence reaction mechanisms and neutral adaptation processes were activated in response to competitive (T. atroviride) or non-competitive (A. mellea) microorganisms, respectively. Moreover, activation of resistance mechanisms dominated in the simplified soil microcosm in the presence of both A. mellea and T. atroviride. Biocontrol processes of T. atroviride were already activated during incubation in the simplified soil microcosm, possibly to occupy niches in a competitive ecosystem, and they were not further enhanced by the introduction of A. mellea. This work represents an additional step towards understanding molecular interactions between plant pathogens and biocontrol

ENANTIOSELECTIVE REDUCTIVE TRANSFORMATION OF CHIRAL POLYCHLORINATED BIPHENYLS IN LAKE SEDIMENT MICROCOSMS

EPA Science Inventory

The transformation rates and enantiomeric ratios of two chiral poylchlorinated biphenyls (PCBs), 2,2',3,4',5',6-hexachlorobiphenyl (2,2',3,4',5',6-HCB) and 2,2',3,3',4,4',5,6-octachlorobiphenyl (2,2',3,3',4,4',5,6-OCB), were determined in anaerobic lake sediment microcosms (25oC)...

Terrestrial Microcosm Evaluation of Two Army Smoke-Producing Compounds.

DTIC Science & Technology

1988-01-29

a greenhouse under natural or controlled photoperiods (depending on the time of year) with rainfall input simulated. Parameters monitored S ’a. ’ ’a...Sixty intact soil-core microcosms that had been extracted from an undisturbed (for m. iy years) field site were set up in a greenhouse under strict...tests. The 60 cures were divided equally between two greenhouse bays, 30 cores for exposure to RP/BR and 30 cores for exposure to WP. Within each group

BIODEGRADATION OF POLYCYCLIC AROMATIC HYDROCARBONS (PAH) FROM CRUDE OIL IN SANDY-BEACH MICROCOSMS.

EPA Science Inventory

Though the lower n-alkanes are considered the most degradable components of crude oil, our experiments with microcosms simulating oiled beaches showed substantial depletion of fluorene, phenanthrene, dibenzothiophene, and other PAH in control treatments consisting of raw seawater...

Fate of pathogenic bacteria in microcosms mimicking human body sites.

PubMed

Castellani, Francesco; Ghidini, Valentina; Tafi, Maria Carla; Boaretti, Marzia; Lleo, Maria M

2013-07-01

During the infectious process, pathogens may reach anatomical sites where they are exposed to substances interfering with their growth. These substances can include molecules produced by the host, and his resident microbial population, as well as exogenous antibacterial drugs. Suboptimal concentrations of inhibitory molecules and stress conditions found in vivo (high or low temperatures, lack of oxygen, extreme pH) might induce in bacteria the activation of survival mechanisms blocking their division capability but allowing them to stay alive. These "dormant" bacteria can be reactivated in particular circumstances and would be able to express their virulence traits. In this study, it was evaluated the effect of some environmental conditions, such as optimal and suboptimal temperatures, direct light and antibiotic sub-inhibitory concentrations doses of antibiotic, on the human pathogens Escherichia coli and Enterococcus faecalis when incubated in fluids accumulated in the body of patients with different pathologies. It is shown that inoculation in a number of accumulated body fluids and the presence of gentamicin, reliable conditions encountered during pathological states, induce stress-responding strategies enabling bacteria to persist in microcosms mimicking the human body. Significant differences were detected in Gram-negative and Gram-positive species with E. faecalis surviving, as starved or viable but non-culturable forms, in any microcosm and condition tested and E. coli activating a viable but non-culturable state only in some clinical samples. The persistence of bacteria under these conditions, being non-culturable, might explain some recurrent infections without isolation of the causative agent after application of the standard microbiological methods.

Biotransformation at 10 C of di-n-butyl phthalate in subsurface microcosms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chauret, C.; Inniss, W.E.; Mayfield, C.I.

1996-09-01

Di-n-butyl phthalate (DBP) was found to be transformed by microorganisms under aerobic and anaerobic conditions at 10 C in microcosms simulating the Canadian Forces Base (CFB) Borden subsurface environment. Biotransformation of DBP was observed under aerobic, nitrate-reducing, Fe(III)-reducing, and sulfate-reducing conditions. The biotransformation of DBP in the microcosms was significantly decrease3d as the redox potential was lowered, especially under sulfate-reducing conditions. However, other factors such as nutrient depletion and buildup of toxic intermediates could have affected the biotransformation rates. The highest DBP biotransformation rate (0.57 {micro}g DBP{center_dot}g sediment{sup {minus}1}{center_dot}day{sup {minus}1}) was under sulfate-reducing conditions. Biotransformation of DBP at 10 Cmore » was significantly enhanced by the addition of 10 mM NaNO{sub 3} suggesting that both the addition of nitrate and high redox conditions favor its biotransformation in subsurface environments.« less

Applicability of Hydrogen Peroxide in Brown Tide Control – Culture and Microcosm Studies

PubMed Central

Randhawa, Varunpreet; Thakkar, Megha; Wei, Liping

2012-01-01

Brown tide algal blooms, caused by the excessive growth of Aureococcus anophagefferens, recur in several northeastern US coastal bays. Direct bloom control could alleviate the ecological and economic damage associated with bloom outbreak. This paper explored the effectiveness and safety of natural chemical biocide hydrogen peroxide (H2O2) for brown tide bloom control. Culture studies showed that H2O2 at 1.6 mg L−1 effectively eradicated high density A. anophagefferens within 24-hr, but caused no significant growth inhibition in the diatoms, prymnesiophytes, green algae and dinoflagellates of >2–3 μm cell sizes among 12 phytoplankton species tested over 1-week observation. When applied to brown tide bloom prone natural seawater in a microcosm study, this treatment effectively removed the developing brown tide bloom, while the rest of phytoplankton assemblage (quantified via HPLC based marker pigment analyses), particularly the diatoms and green algae, experienced only transient suppression then recovered with total chlorophyll a exceeding that in the controls within 72-hr; cyanobacteria was not eradicated but was still reduced about 50% at 72-hr, as compared to the controls. The action of H2O2 against phytoplankton as a function of cell size and cell wall structure, and a realistic scenario of H2O2 application were discussed. PMID:23082223

Hydrocarbon biodegradation by Arctic sea-ice and sub-ice microbial communities during microcosm experiments, Northwest Passage (Nunavut, Canada).

PubMed

Garneau, Marie-Ève; Michel, Christine; Meisterhans, Guillaume; Fortin, Nathalie; King, Thomas L; Greer, Charles W; Lee, Kenneth

2016-10-01

The increasing accessibility to navigation and offshore oil exploration brings risks of hydrocarbon releases in Arctic waters. Bioremediation of hydrocarbons is a promising mitigation strategy but challenges remain, particularly due to low microbial metabolic rates in cold, ice-covered seas. Hydrocarbon degradation potential of ice-associated microbes collected from the Northwest Passage was investigated. Microcosm incubations were run for 15 days at -1.7°C with and without oil to determine the effects of hydrocarbon exposure on microbial abundance, diversity and activity, and to estimate component-specific hydrocarbon loss. Diversity was assessed with automated ribosomal intergenic spacer analysis and Ion Torrent 16S rRNA gene sequencing. Bacterial activity was measured by (3)H-leucine uptake rates. After incubation, sub-ice and sea-ice communities degraded 94% and 48% of the initial hydrocarbons, respectively. Hydrocarbon exposure changed the composition of sea-ice and sub-ice communities; in sea-ice microcosms, Bacteroidetes (mainly Polaribacter) dominated whereas in sub-ice microcosms, the contribution of Epsilonproteobacteria increased, and that of Alphaproteobacteria and Bacteroidetes decreased. Sequencing data revealed a decline in diversity and increases in Colwellia and Moritella in oil-treated microcosms. Low concentration of dissolved organic matter (DOM) in sub-ice seawater may explain higher hydrocarbon degradation when compared to sea ice, where DOM was abundant and composed of labile exopolysaccharides. © Fisheries and Oceans Canada [2016].

Effects of hydrocarbon contamination on a free living marine nematode community: results from microcosm experiments.

PubMed

Mahmoudi, Ezzeddine; Essid, Naceur; Beyrem, Hamouda; Hedfi, Amor; Boufahja, Fehmi; Vitiello, Pierre; Aissa, Patricia

2005-11-01

Anthropogenic inputs of crude and refined petroleum hydrocarbons into the sea require knowledge of the effects of these contaminants on the receiving assemblages of organisms. A microcosm experiment was carried out to study the influence of diesel on a free living nematode community of a Tunisian lagoon. Sediments were contaminated by diesel that ranged in concentration from 0.5 to 20 mg diesel kg(-1) dry weight (dw), and effects were examined after 90 days. Gradual changes in community structure were revealed depending on the quantity of diesel administrated. In the medium (1 mg diesel kg(-1) and 5 mg diesel kg(-1) (dw)) and high (10 mg diesel kg(-1), 15 mg diesel kg(-1) and 20 mg kg(-1) (dw)) treated microcosms, most univariate measures, including diversity and species richness, decreased significantly with increasing level of diesel contamination whereas nematode assemblage from the low treated microcosm (0.5 mg diesel kg(-1) (dw)) remained unaffected. Results from multivariate analyses of the species abundance data demonstrated that responses of nematode species to the diesel treatments were varied: Chaetonema sp. was eliminated at all doses tested and seemed to be intolerant species to diesel contamination; Pomponema sp. and Oncholaimus campylocercoïdes were significantly affected at all diesel contamination levels but they were not eliminated, these species were categorized as "diesel-sensitive"; Hypodontolaimus colesi, Daptonema trabeculosum and Daptonema fallax which significantly increased respectively at 0.5, 1 and 5 mg diesel kg(-1) (dw) concentrations and appeared to be "opportunistic" species at these doses whereas Marylynnia stekhoveni which increased at all high doses (10, 15 and 20 mg diesel kg(-1) (dw)) seemed to be a "diesel-resistant" species.

Habitat Complexity in Aquatic Microcosms Affects Processes Driven by Detritivores

PubMed Central

Flores, Lorea; Bailey, R. A.; Elosegi, Arturo; Larrañaga, Aitor; Reiss, Julia

2016-01-01

Habitat complexity can influence predation rates (e.g. by providing refuge) but other ecosystem processes and species interactions might also be modulated by the properties of habitat structure. Here, we focussed on how complexity of artificial habitat (plastic plants), in microcosms, influenced short-term processes driven by three aquatic detritivores. The effects of habitat complexity on leaf decomposition, production of fine organic matter and pH levels were explored by measuring complexity in three ways: 1. as the presence vs. absence of habitat structure; 2. as the amount of structure (3 or 4.5 g of plastic plants); and 3. as the spatial configuration of structures (measured as fractal dimension). The experiment also addressed potential interactions among the consumers by running all possible species combinations. In the experimental microcosms, habitat complexity influenced how species performed, especially when comparing structure present vs. structure absent. Treatments with structure showed higher fine particulate matter production and lower pH compared to treatments without structures and this was probably due to higher digestion and respiration when structures were present. When we explored the effects of the different complexity levels, we found that the amount of structure added explained more than the fractal dimension of the structures. We give a detailed overview of the experimental design, statistical models and R codes, because our statistical analysis can be applied to other study systems (and disciplines such as restoration ecology). We further make suggestions of how to optimise statistical power when artificially assembling, and analysing, ‘habitat complexity’ by not confounding complexity with the amount of structure added. In summary, this study highlights the importance of habitat complexity for energy flow and the maintenance of ecosystem processes in aquatic ecosystems. PMID:27802267

ANAEROBIC SOIL DISINFESTATION IN MICROCOSMS OF TWO SANDY SOILS.

PubMed

Stremińska, M A; Runia, W T; Termorshuizen, A J; Feil, H; Van Der Wurff, A W G

2014-01-01

In recent years, anaerobic soil disinfestation (ASD) has been proposed as an alternative control method of soil-borne plant pathogens. It involves adding a labile carbon source, irrigating the soil to stimulate decomposition of organic material and then covering the soil with air-tight plastic to limit gas exchange. During the ASD process, soil microorganisms switch from aerobic to anaerobic metabolism. As a result, by-products of anaerobic metabolism are released into the soil environment such as various organic acids and gases. These by-products are reported to have a negative effect on survival of soil-borne plant pathogens. However, the efficacy of ASD to reduce soil-borne pathogens in practice may vary significantly. Therefore, we studied the efficacy of the ASD process in two different soils. In addition, it was investigated whether a pre-treatment with an anaerobic bacterial inoculum prior to ASD affected the efficacy of the process. Two sandy soils (dune sand and glacial sand) were inoculated in 2 L soil microcosms. We tested the efficacy of ASD treatment against the potato cyst nematode Globodera pallida. For each soil, three treatments were used: control treatment (no Herbie addition, aerobic incubation), ASD 1 (organic substrate addition, anaerobic incubation) and ASD 2 (organic substrate and anaerobic bacterial inoculum addition, anaerobic incubation). Soil microcosms were incubated in the dark at 20°C for two weeks. We observed that anaerobic soil disinfestation treatments were highly effective against Potato Cyst Nematode (PCN), with pathogen being eradicated totally in all but one ASD treatment (glacial sand ASD2) within two weeks. The relative abundance of Firmicutes (spore-forming bacteria, often fermentative) in total bacteria increased significantly in ASD treated soils. Numbers of these bacteria correlated positively with increased concentrations of acetic and butyric acids in soil water phase in ASD treatments.

The effects of high-tannin leaf litter from transgenic poplars on microbial communities in microcosm soils.

PubMed

Winder, Richard S; Lamarche, Josyanne; Constabel, C Peter; Hamelin, Richard C

2013-01-01

The impacts of leaf litter from genetically modified hybrid poplar accumulating high levels of condensed tannins (proanthocyanidins) were examined in soil microcosms consisting of moss growing on sieved soil. Moss preferentially proliferated in microcosms with lower tannin content; DGGE (denaturing gradient gel electrophoresis) detected increased fungal diversity in microcosms with low-tannin litter. The proportion of cloned rDNA sequences from Actinobacteria decreased with litter addition while Bacteroidetes, Chloroflexi, Cyanobacteria, and α-Proteobacteria significantly increased. β-Proteobacteria were proportionally more numerous at high-tannin levels. Tannins had no significant impact on overall diversity of bacterial communities analyzed with various estimators. There was an increased proportion of N-fixing bacteria corresponding to the addition of litter with low-tannin levels. The addition of litter increased the proportion of Ascomycota/Basidiomycota. Dothideomycetes, Pucciniomycetes, and Tremellomycetes also increased and Agaricomycetes decreased. Agaricomycetes and Sordariomycetes were significantly more abundant in controls, whereas Pucciniomycetes increased in soil with litter from transformed trees (P = 0.051). Richness estimators and diversity indices revealed no significant difference in the composition of fungal communities; PCoA (principal coordinate analyses) partitioned the fungal communities into three groups: (i) those with higher amounts of added tannin from both transformed and untransformed treatments, (ii) those corresponding to soils without litter, and (iii) those corresponding to microcosms with litter added from trees transformed only with a β-glucuronidase control vector. While the litter from transformed poplars had significant effects on soil microbe communities, the observed impacts reflected known impacts on soil processes associated with tannins, and were similar to changes that would be expected from natural variation in

In-situ Subaqueous Capping of Mercury-Contaminated Sediments in a Fresh-Water Aquatic System, Part I-Bench-Scale Microcosm Study to Assess Methylmercury Production

EPA Science Inventory

Bench-scale microcosm experiments were designed to provide a better understanding of the potential for Hg methylation in sediments from an aquatic environment. Experiments were conducted to examine the function of sulfate concentration, lactate concentration, the presence/absenc...

Genotypic variability enhances the reproducibility of an ecological study.

PubMed

Milcu, Alexandru; Puga-Freitas, Ruben; Ellison, Aaron M; Blouin, Manuel; Scheu, Stefan; Freschet, Grégoire T; Rose, Laura; Barot, Sebastien; Cesarz, Simone; Eisenhauer, Nico; Girin, Thomas; Assandri, Davide; Bonkowski, Michael; Buchmann, Nina; Butenschoen, Olaf; Devidal, Sebastien; Gleixner, Gerd; Gessler, Arthur; Gigon, Agnès; Greiner, Anna; Grignani, Carlo; Hansart, Amandine; Kayler, Zachary; Lange, Markus; Lata, Jean-Christophe; Le Galliard, Jean-François; Lukac, Martin; Mannerheim, Neringa; Müller, Marina E H; Pando, Anne; Rotter, Paula; Scherer-Lorenzen, Michael; Seyhun, Rahme; Urban-Mead, Katherine; Weigelt, Alexandra; Zavattaro, Laura; Roy, Jacques

2018-02-01

Many scientific disciplines are currently experiencing a 'reproducibility crisis' because numerous scientific findings cannot be repeated consistently. A novel but controversial hypothesis postulates that stringent levels of environmental and biotic standardization in experimental studies reduce reproducibility by amplifying the impacts of laboratory-specific environmental factors not accounted for in study designs. A corollary to this hypothesis is that a deliberate introduction of controlled systematic variability (CSV) in experimental designs may lead to increased reproducibility. To test this hypothesis, we had 14 European laboratories run a simple microcosm experiment using grass (Brachypodium distachyon L.) monocultures and grass and legume (Medicago truncatula Gaertn.) mixtures. Each laboratory introduced environmental and genotypic CSV within and among replicated microcosms established in either growth chambers (with stringent control of environmental conditions) or glasshouses (with more variable environmental conditions). The introduction of genotypic CSV led to 18% lower among-laboratory variability in growth chambers, indicating increased reproducibility, but had no significant effect in glasshouses where reproducibility was generally lower. Environmental CSV had little effect on reproducibility. Although there are multiple causes for the 'reproducibility crisis', deliberately including genetic variability may be a simple solution for increasing the reproducibility of ecological studies performed under stringently controlled environmental conditions.

Microcosm experiments approach to quantify nitrogen leaching from mineral and organic fertilized soil

NASA Astrophysics Data System (ADS)

Severus Sandor, Mignon; Sandor, Valentina; Mihai Onica, Bogdan; Brad, Traian

2017-04-01

The use of nitrogen inputs to improve agricultural soils fertility is a common practice in arable lands. Depending of nitrogen forms only a part of introduced nitrogen will be effectively used by the crops while another part can be leached from soil with negative impact on the environment. In temperate climate these losses are greater during spring time when rains are frequent and crop plants are in the early growth stage. In a microcosm experiments we simulated this kind of conditions in order to assess nitrogen losses from two different soils (Chernozem, Luvisol) fertilized with mineral (ammonium nitrate) and organic (mustard as green manure, slurry manure and cattle manure) fertilizers. From each microcosms we obtained 100 ml of leachate which was filtered and analyzed from N-NO3 and N-NH4. The leachate was obtained by adding distillate water at the microcosm surface two times during the experiment at a ten days interval. Preliminary results showed that only small quantity of ammonium was leached from fertilized soils, mainly after 20 days of incubation. These amounts were higher in Chernozem soil than in Luvisol and registered the highest amount in cattle manure fertilized soils. In general, the nitrate was leached from soils in high quantities. The highest value was measured in Chernozem soil when cattle manure was used as fertilizer (1200 mg/l) and represents a cumulative amount. For most of the treatments the cumulative loss of nitrate nitrogen was double in Chernozem soil than in Luvisol. The highest quantity of leaching nitrate was measured for both soils in manure fertilized soil.

Persistence of pentolite (PETN and TNT) in soil microcosms and microbial enrichment cultures.

PubMed

Arbeli, Ziv; Garcia-Bonilla, Erika; Pardo, Cindy; Hidalgo, Kelly; Velásquez, Trigal; Peña, Luis; C, Eliana Ramos; Avila-Arias, Helena; Molano-Gonzalez, Nicolás; Brandão, Pedro F B; Roldan, Fabio

2016-05-01

Pentolite is a mixture (1:1) of 2,4,6-trinitrotoluene (TNT) and pentaerythritol tetranitrate (PETN), and little is known about its fate in the environment. This study was aimed to determine the dissipation of pentolite in soils under laboratory conditions. Microcosm experiments conducted with two soils demonstrated that dissipation rate of PETN was significantly slower than that of TNT. Interestingly, the dissipation of PETN was enhanced by the presence of TNT, while PETN did not enhanced the dissipation of TNT. Pentolite dissipation rate was significantly faster under biostimulation treatment (addition of carbon source) in soil from the artificial wetland, while no such stimulation was observed in soil from detonation field. In addition, the dissipation rate of TNT and PETN in soil from artificial wetland under biostimulation was significantly faster than the equivalent abiotic control, although it seems that non-biological processes might also be important for the dissipation of TNT and PETN. Transformation of PETN was also slower during establishment of enrichment culture using pentolite as the sole nitrogen source. In addition, transformation of these explosives was gradually reduced and practically stopped after the forth cultures transfer (80 days). DGGE analysis of bacterial communities from these cultures indicates that all consortia were dominated by bacteria from the order Burkholderiales and Rhodanobacter. In conclusion, our results suggest that PETN might be more persistent than TNT.

Detection of Salmonella enterica Serovar Montevideo and Newport in Free-ranging Sea Turtles and Beach Sand in the Caribbean and Persistence in Sand and Seawater Microcosms.

PubMed

Ives, A-K; Antaki, E; Stewart, K; Francis, S; Jay-Russell, M T; Sithole, F; Kearney, M T; Griffin, M J; Soto, E

2017-09-01

Salmonellae are Gram-negative zoonotic bacteria that are frequently part of the normal reptilian gastrointestinal flora. The main objective of this project was to estimate the prevalence of non-typhoidal Salmonella enterica in the nesting and foraging populations of sea turtles on St. Kitts and in sand from known nesting beaches. Results suggest a higher prevalence of Salmonella in nesting leatherback sea turtles compared with foraging green and hawksbill sea turtles. Salmonella was cultured from 2/9 and identified by molecular diagnostic methods in 3/9 leatherback sea turtle samples. Salmonella DNA was detected in one hawksbill turtle, but viable isolates were not recovered from any hawksbill sea turtles. No Salmonella was detected in green sea turtles. In samples collected from nesting beaches, Salmonella was only recovered from a single dry sand sample. All recovered isolates were positive for the wzx gene, consistent with the O:7 serogroup. Further serotyping characterized serovars Montevideo and Newport present in cloacal and sand samples. Repetitive-element palindromic PCR (rep-PCR) fingerprint analysis and pulsed-field gel electrophoresis of the 2014 isolates from turtles and sand as well as archived Salmonella isolates recovered from leatherback sea turtles in 2012 and 2013, identified two distinct genotypes and four different pulsotypes, respectively. The genotyping and serotyping were directly correlated. To determine the persistence of representative strains of each serotype/genotype in these environments, laboratory-controlled microcosm studies were performed in water and sand (dry and wet) incubated at 25 or 35°C. Isolates persisted for at least 32 days in most microcosms, although there were significant decreases in culturable bacteria in several microcosms, with the greatest reduction in dry sand incubated at 35°C. This information provides a better understanding of the epizootiology of Salmonella in free-ranging marine reptiles and the potential

Dental plaque microcosm biofilm behavior on calcium phosphate nanocomposite with quaternary ammonium.

PubMed

Cheng, Lei; Weir, Michael D; Zhang, Ke; Wu, Eric J; Xu, Sarah M; Zhou, Xuedong; Xu, Hockin H K

2012-08-01

Half of dental restorations fail in 10 years, with secondary caries as the main reason. Calcium phosphate composites could remineralize tooth lesions. The objectives of this study were to: (1) impart antibacterial activity to a composite with nanoparticles of amorphous calcium phosphate (NACP); and (2) investigate the effect of quaternary ammonium dimethacrylate (QADM) on mechanical and dental plaque microcosm biofilm properties for the first time. The NACP and glass particles were filled into a dental resin that contained bis(2-methacryloyloxy-ethyl) dimethyl-ammonium bromide, the QADM. NACP nanocomposites containing 0%, 7%, 14%, and 17.5% of QADM by mass, respectively, were photo-cured. A commercial composite with no antibacterial activity was used as control. Mechanical properties were measured in three-point flexure. A human saliva microcosm model was used to grow biofilms on composites. Live/dead assay, metabolic activity, colony-forming unit (CFU) counts, and lactic acid production of biofilms on the composites were measured. Increasing QADM mass fraction monotonically reduced the biofilm viability, CFU and lactic acid. Biofilms on NACP nanocomposite with 17.5% QADM had metabolic activity that was 30% that on a commercial composite control (p<0.05). Total microorganisms, total streptococci, and mutans streptococci CFU counts (mean ± sd; n = 6) on composite control was 6-fold those on NACP +17.5% QADM nanocomposite. Composite control had long strings of bacterial cells with normal short-rod shapes, while some cells on NACP-QADM nanocomposites disintegrated into pieces. Adding QADM to NACP did not decrease the composite strength and elastic modulus, which matched (p>0.1) those of a commercial composite without Ca-PO(4) or antibacterial activity. A dental plaque microcosm model was used to evaluate the novel NACP-QADM nanocomposite. The nanocomposite greatly reduced the biofilm viability, metabolic activity and lactic acid, while its mechanical properties

Reductive Dechlorination of 1,2,4-Trichlorobenzene and Its Metabolites at a Contaminated Site in Nanjing, China: Concordance between Field and Microcosm Data

NASA Astrophysics Data System (ADS)

Qiao, W.; Lomheim, L.; Luo, F.; Ye, S.; Wu, J.; Edwards, E.

2016-12-01

Chlorinated benzenes (CBs) are widespread contaminants at many industrial sites, posing a threat to human health and the environment. Bioremediation has the advantage of using natural biological processes to possibly completely destroy target pollutants. A three-year site investigation was conducted from 2012 to 2014 at a former chemical plant in Nanjing, China, which was contaminated by chlorobenzenes (CBs) and benzene. The aquifer was located within a silty clay and clayey silt with extremely low permeability. Soil and groundwater sample analyses revealed that the main contaminants were 1,2,4-tichlorobenzene (TCB) with highest concentration of 7300ug/L, dichlorobenzene (DCB) isomers, monochlorobenzene (MCB) and benzene. The contaminants were mainly located in the vicinity of a former wastewater basin and production facilities of chemical products. TCB was used as a solvent and leaked during the plant manufacturing processes. It is assumed that DCB isomers, MCB and benzene were derived from the anaerobic subsequent dehalogenation of 1,2,4-TCB. A corresponding lab microcosm study was conducted to prove the assumption of indigenous CBs biodegradation. The contaminated soil and groundwater from the site were used to conduct the lab microcosms study to keep the lab experimental conditions the same as the site and to be comparable with the site investigation results. The lab microcosms study results demonstrated that 1,4-DCB, 1,2-DCB and 1,3-DCB were the anaerobic dechlorination product of 1,2,4-TCB, and 1,2-DCB, 1,3-DCB can be transformed to MCB, and benzene can be degraded to CO2 under sulfate reducing condition. The lab microcosms study results were consistent with the site investigation results, which will provide a theoretical proposition on site remediation strategy making. This research method of combing the site investigation with the lab study can be applied and transferable to any other contaminated sites of concern. The site investigation and lab study can

Variation pattern of terrestrial antibiotic resistances and bacterial communities in seawater/freshwater mixed microcosms.

PubMed

Zhang, Kai; Zhang, Ying; Xin, Rui; Zhang, Yongpeng; Niu, Zhiguang

2018-06-01

The ocean is the final place where pollutants generated by human activities are deposited. As a result, the long-range transport of the ocean can facilitate the diffusion of terrestrial contaminants, including ARGs. However, to our knowledge, little research has been devoted to discussing the content change of terrestrial ARGs and the reason for the change in coastal area. This study established various microcosms, in which seawater and freshwater were mixed at different ratio to simulate the environmental conditions of different regions in coastal areas. Four ARGs were quantified, and 16S pyrosequencing was conducted. The results showed that the terrestrial ARGs influenced the concentration of the corresponding ARGs in coastal areas, and the content change pattern of each ARG was distinct. The influence of salinity on the ARG content was limited in most cases. Moreover, most dominant bacteria from freshwater had significant positive correlation (p < 0.05) with selected ARGs, except for bla TEM . The dominant bacteria in freshwater diminished dramatically in microcosms with a high proportion of seawater. Freshwater may have a strong impact on the bacteria composition of seawater, and the materials from freshwater may prompt the growth of some bacteria (include potential hosts of ARGs) in coastal area. Copyright © 2018 Elsevier Ltd. All rights reserved.

CHANGES IN ENANTIOMERIC FRACTIONS DURING MICROBIAL REDUCTIVE DECHLORINATION OF PCB132, PCB149, AND AROCLOR 1254 IN LAKE HARTWELL SEDIMENT MICROCOSMS

EPA Science Inventory

Enantioselectivity of microbial reductive dechlorination of chiral PCBs in sediments from Lake Hartwell, SC, was determined by microcosm studies and enantiomer-specific GC analysis. Sediments from two locations in the vicinity of the highest levels of PCB contamination were used...

Influence of linear alkylbenzene sulfonate (LAS) on the structure of Alphaproteobacteria, Actinobacteria, and Acidobacteria communities in a soil microcosm.

PubMed

Sánchez-Peinado, M del Mar; González-López, Jesús; Martínez-Toledo, M Victoria; Pozo, Clementina; Rodelas, Belén

2010-03-01

Linear alkylbenzene sulfonate (LAS) is the most used anionic surfactant in a worldwide scale and is considered a high-priority pollutant. LAS is regarded as a readily biodegradable product under aerobic conditions in aqueous media and is mostly removed in wastewater treatment plants, but an important fraction (20-25%) is immobilized in sewage sludge and persists under anoxic conditions. Due to the application of the sludge as a fertilizer, LAS reaches agricultural soil, and therefore, microbial toxicity tests have been widely used to evaluate the influence of LAS on soil microbial ecology. However, molecular-based community-level analyses have been seldom applied in studies regarding the effects of LAS on natural or engineered systems, and, to our knowledge, there are no reports of their use for such appraisals in agricultural soil. In this study, a microcosm system is used to evaluate the effects of a commercial mixture of LAS on the community structure of Alphaproteobacteria, Actinobacteria, and Acidobacteria in an agricultural soil. The microcosms consisted of agricultural soil columns (800 g) fed with sterile water (8 ml h(-1)) added of different concentration of LAS (10 or 50 mg l(-1)) for periods of time up to 21 days. Sterile water was added to control columns for comparison. The structures of Alphaproteobacteria, Actinobacteria, and Acidobacteria communities were analyzed by a cultivation independent method (temperature gradient gel electrophoresis (TGGE) separation of polymerase chain reaction (PCR)-amplified partial 16S rRNA genes). Relevant populations were identified by subsequent reamplification, DNA sequencing, and database comparisons. Cluster analysis of the TGGE fingerprints taking into consideration both the number of bands and their relative intensities revealed that the structure of the Alphaproteobacteria community was significantly changed in the presence of LAS, at both concentrations tested. The average number of bands was significantly

Multivariate analysis of the impacts of the turbine fuel JP-4 in a microcosm toxicity test with implications for the evaluation of ecosystem dynamics and risk assessment.

PubMed

Landis, W G; Matthews, R A; Markiewicz, A J; Matthews, G B

1993-12-01

Turbine fuels are often the only aviation fuel available in most of the world. Turbine fuels consist of numerous constituents with varying water solubilities, volatilities and toxicities. This study investigates the toxicity of the water soluble fraction (WSF) of JP-4 using the Standard Aquatic Microcosm (SAM). Multivariate analysis of the complex data, including the relatively new method of nonmetric clustering, was used and compared to more traditional analyses. Particular emphasis is placed on ecosystem dynamics in multivariate space.The WSF is prepared by vigorously mixing the fuel and the SAM microcosm media in a separatory funnel. The water phase, which contains the water-soluble fraction of JP-4 is then collected. The SAM experiment was conducted using concentrations of 0.0, 1.5 and 15% WSF. The WSF is added on day 7 of the experiments by removing 450 ml from each microcosm including the controls, then adding the appropriate amount of toxicant solution and finally bringing the final volume to 3 L with microcosm media. Analysis of the WSF was performed by purge and trap gas chromatography. The organic constituents of the WSF were not recoverable from the water column within several days of the addition of the toxicant. However, the impact of the WSF on the microcosm was apparent. In the highest initial concentration treatment group an algal bloom ensued, generated by the apparent toxicity of the WSF of JP-4 to the daphnids. As the daphnid populations recovered the algal populations decreased to control values. Multivariate methods clearly demonstrated this initial impact along with an additional oscillation seperating the four treatment groups in the latter segment of the experiment. Apparent recovery may be an artifact of the projections used to describe the multivariate data. The variables that were most important in distinguishing the four groups shifted during the course of the 63 day experiment. Even this simple microcosm exhibited a variety of dynamics

Evaluation of ethyl tert-butyl ether biodegradation in a contaminated aquifer by compound-specific isotope analysis and in situ microcosms.

PubMed

Bombach, Petra; Nägele, Norbert; Rosell, Mònica; Richnow, Hans H; Fischer, Anko

2015-04-09

Ethyl tert-butyl ether (ETBE) is an upcoming groundwater pollutant in Europe whose environmental fate has been less investigated, thus far. In the present study, we investigated the in situ biodegradation of ETBE in a fuel-contaminated aquifer using compound-specific stable isotope analysis (CSIA), and in situ microcosms in combination with total lipid fatty acid (TLFA)-stable isotope probing (SIP). In a first field investigation, CSIA revealed insignificant carbon isotope fractionation, but low hydrogen isotope fractionation of up to +14‰ along the prevailing anoxic ETBE plume suggesting biodegradation of ETBE. Ten months later, oxygen injection was conducted to enhance the biodegradation of petroleum hydrocarbons (PH) at the field site. Within the framework of this remediation measure, in situ microcosms loaded with [(13)C6]-ETBE (BACTRAP(®)s) were exposed for 119 days in selected groundwater wells to assess the biodegradation of ETBE by TLFA-SIP under the following conditions: (i) ETBE as main contaminant; (ii) ETBE as main contaminant subjected to oxygen injection; (iii) ETBE plus other PH; (iv) ETBE plus other PH subjected to oxygen injection. Under all conditions investigated, significant (13)C-incorporation into microbial total lipid fatty acids extracted from the in situ microcosms was found, providing clear evidence of ETBE biodegradation. Copyright © 2014 Elsevier B.V. All rights reserved.

Laboratory evidence of MTBE biodegradation in Borden aquifer material

NASA Astrophysics Data System (ADS)

Schirmer, Mario; Butler, Barbara J.; Church, Clinton D.; Barker, James F.; Nadarajah, Nalina

2003-02-01

Mainly due to intrinsic biodegradation, monitored natural attenuation can be an effective and inexpensive remediation strategy at petroleum release sites. However, gasoline additives such as methyl tert-butyl ether (MTBE) can jeopardize this strategy because these compounds often degrade, if at all, at a slower rate than the collectively benzene, toluene, ethylbenzene and the xylene (BTEX) compounds. Investigation of whether a compound degrades under certain conditions, and at what rate, is therefore important to the assessment of the intrinsic remediation potential of aquifers. A natural gradient experiment with dissolved MTBE-containing gasoline in the shallow, aerobic sand aquifer at Canadian Forces Base (CFB) Borden (Ontario, Canada) from 1988 to 1996 suggested that biodegradation was the main cause of attenuation for MTBE within the aquifer. This laboratory study demonstrates biologically catalyzed MTBE degradation in Borden aquifer-like environments, and so supports the idea that attenuation due to biodegradation may have occurred in the natural gradient experiment. In an experiment with batch microcosms of aquifer material, three of the microcosms ultimately degraded MTBE to below detection, although this required more than 189 days (or >300 days in one case). Failure to detect the daughter product tert-butyl alcohol (TBA) in the field and the batch experiments could be because TBA was more readily degradable than MTBE under Borden conditions.

Monitoring Arthrobacter protophormiae RKJ100 in a 'tag and chase' method during p-nitrophenol bio-remediation in soil microcosms.

PubMed

Pandey, Gunjan; Pandey, Janmejay; Jain, Rakesh K

2006-05-01

Monitoring of micro-organisms released deliberately into the environment is essential to assess their movement during the bio-remediation process. During the last few years, DNA-based genetic methods have emerged as the preferred method for such monitoring; however, their use is restricted in cases where organisms used for bio-remediation are not well characterized or where the public domain databases do not provide sufficient information regarding their sequence. For monitoring of such micro-organisms, alternate approaches have to be undertaken. In this study, we have specifically monitored a p-nitrophenol (PNP)-degrading organism, Arthrobacter protophormiae RKJ100, using molecular methods during PNP degradation in soil microcosm. Cells were tagged with a transposon-based foreign DNA sequence prior to their introduction into PNP-contaminated microcosms. Later, this artificially introduced DNA sequence was PCR-amplified to distinguish the bio-augmented organism from the indigenous microflora during PNP bio-remediation.

Effects of reclamation on macrobenthic assemblages in the coastline of the Arabian Gulf: a microcosm experimental approach.

PubMed

Naser, Humood A

2011-03-01

Coastal reclamation and modifications are extensively carried out in Bahrain, which may physically smother the coastal and subtidal habitats resulting in changes to abundance and distribution of macrobenthic assemblages. A microcosm laboratory experiment using three common macrobenthic invertebrates from a proposed reclaimed coastal area was preformed to examine their responses to mud burial using marine sediment collected from a designated borrow area. Significant difference in numbers of survived organisms between control and experimental treatments with a survival percentage of 41.8% for all of the selected species was observed. The polychaete Perinereis nuntia showed the highest percentage of survival (57.1%) followed by the bivalve Tellinavaltonis (42.3%) and the gastropod Cerithidea cingulata (24.0%). Quantifying species responses to sediment burial resulted from dredging and reclamation will aid in predicting the expected ecological impacts associated with coastal developments and subsequently minimizing these impacts and maintaining a sustainable use of coastal and marine ecosystems in the Arabian Gulf. Copyright © 2010 Elsevier Ltd. All rights reserved.

Prairie restoration at the National Wildlife Health Laboratory (Wisconsin)

USGS Publications Warehouse

Windingstad, R.M.

1986-01-01

The National Wildlife Health Laboratory (NWHL), U.S. Fish and Wildlife Service in Madison are in the process of a 7-ha prairie restoration project on their lands to create a microcosmic representation of presettlement Wisconsin. Visiting scientists, personnel from local schools and universities, and neighboring public will eventually be able to use this land for its educational and esthetic value while becoming more familiar with the goals and objectives of the Fish and Wildlife Service and the NWHL. Self-guiding nature trails and a kiosk will facilitate public use after the project is completed.

Determining the effects of pollutants on soil faunal communities and trophic structure using a refined microcosm system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parmelee, R.W.; Phillips, C.T.; Checkai, R.T.

1997-06-01

The authors used a refined microcosm technique to investigate the toxicity of copper, cadmium, malathion, and the polychlorinated biphenyl, to trophic groups of soil nematodes and to the microarthropod community. Comparisons of changes in nematode abundance in control soils through time indicated that day 7 was the most appropriate time to sample the microcosms after chemical application. Nematode abundance was reduced after exposure to copper at 100 {micro}g/g, with fungivore, bacterivore, and omnivore-predator nematodes being the most sensitive groups. Cadmium did not affect the nematode or microarthropod communities. Microarthropods were far more sensitive to malathion than were nematodes, and totalmore » microarthropod abundance was lower than controls at 400 {micro}g/g. Prostigmatid mites and other arthropods were the most affected groups. PCB also had a greater negative impact on microarthropods than on nematodes. Total microarthropod abundance declined at 2,500 {micro}g/g, with prostigmatid and oribatid mites exhibiting the highest susceptibility. Strong differential sensitivity between nematode and microarthropod communities indicates that both groups should be examined to fully evaluate the biological impact of chemicals on soils. The authors conclude that microcosms with field-collected soil microfaunal communities offer high resolution of the ecotoxicologic effects of chemicals in complex soil systems.« less

Effects of acute gamma-irradiation on the aquatic microbial microcosm in comparison with chemicals.

PubMed

Fuma, Shoichi; Ishii, Nobuyoshi; Takeda, Hiroshi; Miyamoto, Kiriko; Yanagisawa, Kei; Doi, Kazutaka; Kawaguchi, Isao; Tanaka, Nobuyuki; Inamori, Yuhei; Polikarpov, Gennady G

2009-12-01

Effects of acute gamma-irradiation were investigated in the aquatic microcosm consisting of green algae (Chlorella sp. and Scenedesmus sp.) and a blue-green alga (Tolypothrix sp.) as producers; an oligochaete (Aeolosoma hemprichi), rotifers (Lecane sp. and Philodina sp.) and a ciliate protozoan (Cyclidium glaucoma) as consumers; and more than four species of bacteria as decomposers. At 100 Gy, populations were not affected in any taxa. At 500-5000 Gy, one or three taxa died out and populations of two or three taxa decreased over time, while that of Tolypothrix sp. increased. This Tolypothrix sp. increase was likely an indirect effect due to interspecies interactions. The principal response curve analysis revealed that the main trend of the effects was a dose-dependent population decrease. For a better understanding of radiation risks in aquatic microbial communities, effect doses of gamma-rays compared with copper, herbicides and detergents were evaluated using the radiochemoecological conceptual model and the effect index for microcosm.

Trichloroacetic acid (TCA) and trifluoroacetic acid (TFA) mixture toxicity to the macrophytes Myriophyllum spicatum and Myriophyllum sibiricum in aquatic microcosms.

PubMed

Hanson, Mark L; Sibley, Paul K; Mabury, Scott A; Solomon, Keith R; Muir, Derek C G

2002-02-21

Trichloroacetic acid (TCA) and trifluoroacetic acid (TFA) have been detected together in environmental water samples throughout the world. TCA may enter into aquatic systems via rainout as the degradation product of chlorinated solvents, herbicide use, as a by-product of water disinfection and from emissions of spent bleach liquor of kraft pulp mills. Sources of TFA include degradation of hydrofluorocarbons (HFCs) refrigerants and pesticides. These substances are phytotoxic and widely distributed in aquatic environments. A study to assess the risk of a binary mixture of TCA and TFA to macrophytes in aquatic microcosms was conducted as part of a larger study on haloacetic acids. M. spicatum and M. sibiricum were exposed to 0.1, 1, 3 and 10 mg/l of both TCA and TFA (neutralized with sodium hydroxide) in replicate (n = 3) 12000 l aquatic microcosms for 49 days in an one-way analysis of variance design. Each microcosm was stocked with 14 individual apical shoots per species. The plants were sampled at regular intervals and assessed for the somatic endpoints of plant length, root growth, number of nodes and wet and dry mass and the biochemical endpoints of chlorophyll-a, chlorophyll-b, carotenoid content and citric acid levels. Results indicate that there were statistically significant effects of the TCA/TFA mixture on certain pigment concentrations immediately after the start of exposure (2-7 days), but the plants showed no signs of stress thereafter. These data suggest that TCA/TFA mixtures at environmentally relevant concentrations do not pose a significant risk to these aquatic macrophytes.

The effect of chronic silver nanoparticles on aquatic system in microcosms.

PubMed

Jiang, Hong Sheng; Yin, Liyan; Ren, Na Na; Xian, Ling; Zhao, Suting; Li, Wei; Gontero, Brigitte

2017-04-01

Silver nanoparticles (AgNPs) inevitably discharge into aquatic environments due to their abundant use in antibacterial products. It was reported that in laboratory conditions, AgNPs display dose-dependent toxicity to aquatic organisms, such as bacteria, algae, macrophytes, snails and fishes. However, AgNPs could behave differently in natural complex environments. In the present study, a series of microcosms were established to investigate the distribution and toxicity of AgNPs at approximately 500 μg L -1 in aquatic systems. As a comparison, the distribution and toxicity of the same concentration of AgNO 3 were also determined. The results showed that the surface layer of sediment was the main sink of Ag element for both AgNPs and AgNO 3 . Both aquatic plant (Hydrilla verticillata) and animals (Gambusia affinis and Radix spp) significantly accumulated Ag. With short-term treatment, phytoplankton biomass was affected by AgNO 3 but not by AgNPs. Chlorophyll content of H. verticillata increased with both AgNPs and AgNO 3 short-term exposure. However, the biomass of phytoplankton, aquatic plant and animals was not significantly different between control and samples treated with AgNPs or AgNO 3 for 90 d. The communities, diversity and richness of microbes were not significantly affected by AgNPs and AgNO 3 ; in contrast, the nitrification rate and its related microbe (Nitrospira) abundance significantly decreased. AgNPs and AgNO 3 may affect the nitrogen cycle and affect the environment and, since they might be also transferred to food web, they represent a risk for health. Copyright © 2017 Elsevier Ltd. All rights reserved.

Recent advances in the use of estuarine meiobenthos to assess contaminated sediment effects in multi-species whole sediment microcosms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandler, G.T.; Coull, B.C.; Schizas, N.V.

1995-12-31

Many marine meiobenthic taxa (i.e. invertebrates passing a 1-mm sieve but retaining on a 0.063 mm sieve) are ideal for ``whole-sediment`` and porewater bioassay of sedimented pollutants. Annual production of meiobenthos is 5--10 times that of the more commonly studied macrobenthos, and > 95% of all meiobenthos live in the oxic zone of muddy sediments at densities of 4--12 million per M{sup 2}. Most spend their entire lifecycles, burrowing freely and feeding on/within the sediment:porewater matrix, many taxa undergo 10--14 generations per year, most larval/juvenile stages are benthic, and many have easily quantifiable reproductive output. Furthermore, many meiobenthic taxa canmore » be cultured indefinitely over multiple life-cycles within simple sediment microcosms consisting of sealed whole-sediment cores collected intact from intertidal mudflats. The authors describe several recent technical developments exploiting meiofaunal sediment culture for rapid contaminated sediment bioassays of toxicant effects on survival, reproduction and population growth of meiobenthic taxa in whole-sediment microcosms. Currently meiobenthic copepods, nematodes, foraminifers and polychaetes are being continuously cultured to study these parameters under exposure to model sediment-associated toxicants (e.g. cadmium). Bioassays are run for 21-d under flowing seawater. With this approach, fertile benthic copepods (e.g. Amphiascus tenuiremis) can be added to core microcosms to assess survival and growth of a fixed population cohort. All other meiobenthic taxa are enumerated relative to controls and evaluated for toxicant effects on higher order community-level endpoints. This approach exploits meiobenthos` high abundance and rapid reproductive rates to yield on a micro scale better endpoints than much larger sediment mesocosms targeted at macrofaunal endpoints.« less

Investigation into ammonia stress on Cyperus alternifolius and its impact on nutrient removal in microcosm experiments.

PubMed

Tao, Wendong; Han, Jianqiu; Li, Hanyan

2015-11-01

Ammonia stress on plants has been investigated at discrete ammonia concentrations in constructed wetlands. This study introduced a Gaussian model to simulate the kinetics of ammonia stress and investigated reversible and irreversible ammonia stress on Cyperus alternifolius in wetland-like microcosms. Ammonia stress on plant weight increase and oxygen release potential started at weekly ammonia concentrations of 27 and 28 mg N/L, reached 50% inhibition at 178 and 158 mg N/L, and resulted in lethal effects at 311 and 303 mg N/L, respectively. The stress of one-time ammonia concentrations up to 400 mg N/L could be reversible. Ammonia concentrations constantly above 219 mg N/L exerted irreversible stress. In the microcosms with ammonia concentrations above the 50% inhibition levels, plants played a minor role in nitrogen removal. Nitrogen removal performance was not affected considerably by ammonia stress. Orthophosphate removal was suppressed by ammonia stress due to less plant uptake. Design and operation of constructed wetlands should consider wastewater ammonia concentration so that the integrity of constructed wetland ecosystems can be maintained. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects Of Nutrient Source And Supply On Crude Oil Biodegradation In Continuous-Flow Beach Microcosms

EPA Science Inventory

Ammonium and nitrate were used as nitrogen sources to support microbial biodegradation of crude oil in continuous-flow beach microcosms to determine whether either nutrient was more effective in open systems, such as intertidal shorelines. No differences in the rate or the exten...

Distinct succession patterns of abundant and rare bacteria in temporal microcosms with pollutants.

PubMed

Jiao, Shuo; Luo, Yantao; Lu, Mingmei; Xiao, Xiao; Lin, Yanbing; Chen, Weimin; Wei, Gehong

2017-06-01

Elucidating the driving forces behind the temporal dynamics of abundant and rare microbes is essential for understanding the assembly and succession of microbial communities. Here, we explored the successional trajectories and mechanisms of abundant and rare bacteria via soil-enrichment subcultures in response to various pollutants (phenanthrene, n-octadecane, and CdCl 2 ) using time-series Illumina sequencing datasets. The results reveal different successional patterns of abundant and rare sub-communities in eighty pollutant-degrading consortia and two original soil samples. A temporal decrease in α-diversity and high turnover rate for β-diversity indicate that deterministic processes are the main drivers of the succession of the abundant sub-community; however, the high cumulative species richness indicates that stochastic processes drive the succession of the rare sub-community. A functional prediction showed that abundant bacteria contribute primary functions to the pollutant-degrading consortia, such as amino acid metabolism, cellular responses to stress, and hydrocarbon degradation. Meanwhile, rare bacteria contribute a substantial fraction of auxiliary functions, such as carbohydrate-active enzymes, fermentation, and homoacetogenesis, which indicates their roles as a source of functional diversity. Our study suggests that the temporal succession of microbes in polluted microcosms is mainly associated with abundant bacteria rather than the high proportion of rare taxa. The major forces (i.e., stochastic or deterministic processes) driving microbial succession could be dependent on the low- or high-abundance community members in temporal microcosms with pollutants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Wrinkly-Spreader Fitness in the Two-Dimensional Agar Plate Microcosm: Maladaptation, Compensation and Ecological Success

PubMed Central

Spiers, Andrew J.

2007-01-01

Bacterial adaptation to new environments often leads to the establishment of new genotypes with significantly altered phenotypes. In the Wrinkly Spreader (WS), ecological success in static liquid microcosms was through the rapid colonisation of the air-liquid interface by the production of a cellulose-based biofilm. Rapid surface spreading was also seen on agar plates, but in this two-dimensional environment the WS appears maladapted and rapidly reverts to the ancestral smooth (SM)-like colony genotype. In this work, the fitness of WS relative to SM in mixed colonies was found to be low, confirming the WS instability on agar plates. By examining defined WS mutants, the maladaptive characteristic was found to be the expression of cellulose. SM-like revertants had a higher growth rate than WS and no longer expressed significant amounts of cellulose, further confirming that the expression of this high-cost polymer was the basis of maladaptation and the target of compensatory mutation in developing colonies. However, examination of the fate of WS-founded populations in either multiple-colony or single mega-colony agar plate microcosms demonstrated that the loss of WS lineages could be reduced under conditions in which the rapid spreading colony phenotype could dominate nutrient and oxygen access more effectively than competing SM/SM-like genotypes. WS-like isolates recovered from such populations showed increased WS phenotype stability as well as changes in the degree of colony spreading, confirming that the WS was adapting to the two-dimensional agar plate microcosm. PMID:17710140

Methyl t-Butyl Ether Mineralization in Surface-Water Sediment Microcosms under Denitrifying Conditions

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.; Landmeyer, J.E.

2001-01-01

Mineralization of [U-14C] methyl t-butyl ether (MTBE) to 14CO2 without accumulation of t-butyl alcohol (TBA) was observed in surface-water sediment microcosms under denitrifying conditions. Methanogenic activity and limited transformation of MTBE to TBA were observed in the absence of denitrification. Results indicate that bed sediment microorganisms can effectively degrade MTBE to nontoxic products under denitrifying conditions.

In situ microcosms to study the impact of heavy metals resuspended by dredging on periphyton in a tropical estuary.

PubMed

Nayar, S; Goh, B P L; Chou, L M; Reddy, S

2003-08-20

Ponggol estuary, located on the northeastern coast of Singapore, is heavily impacted by reclamation, dredging, construction and shipping. Tin, lead, nickel, cadmium, copper and zinc in the particulate and dissolved fraction and in sediments were monitored biweekly in the estuary from July 1999 to June 2000. The concentrations of tin, lead, nickel, cadmium, copper and zinc were observed to range from ND-92 ppm, ND-303 ppm, ND-2818 ppm, ND-74 ppm, ND-1117 ppm and ND-137000 ppm, respectively, in the dissolved, particulate and sediments fractions. Intensive dredging activity occurred during the monitoring period, and this may have led to the resuspension and increased bioavailability of particulate metals. Periphytic algae were established on glass slides and exposed to previously measured environmental levels of heavy metals using in situ estuarine microcosms. The toxicity of heavy metals in various fractions to periphytic algae was assessed from the changes in their chlorophyll a content. Cadmium had the least significant effect followed by lead, zinc, nickel, tin and copper at all concentrations tested. A reduction in periphyton biomass (with respect to controls) of 95-100% was observed for treatments with metals in particulate form. In addition, exposure to contaminated sediments for 3 days significantly decreased chlorophyll a by 90-99% compared to controls. High concentrations of zinc (9893-17240 mg l(-1)), copper (5-11 mg l(-1)) and cadmium (1-1.8 mg l(-1)) recorded in the aqueous phase of treatment microcosms, and attributed to release from the contaminated sediments, could account for the toxicity to periphyton.

Identification of degradation routes of metamitron in soil microcosms using 13C-isotope labeling.

PubMed

Wang, Shizong; Miltner, Anja; Nowak, Karolina M

2017-01-01

Metamitron is one of the most commonly used herbicide in sugar beet and flower bulb cultures. Numerous laboratory and field studies on sorption and degradation of metamitron were performed. Detailed biodegradation studies in soil using 13 C-isotope labeling are still missing. Therefore, we aimed at providing a detailed turnover mass balance of 13 C 6 -metamitron in soil microcosms over 80 days. In the biotic system, metamitron mineralized rapidly, and 13 CO 2 finally constituted 60% of the initial 13 C 6 -metamitron equivalents. In abiotic control experiments CO 2 rose to only 7.4% of the initial 13 C 6 -metamitron equivalents. The 13 C label from 13 C 6 -metamitron was incorporated into microbial amino acids that were ultimately stabilized in the soil organic matter forming presumably harmless biogenic residues. Finally, 13 C label from 13 C 6 -metamitron was distributed between the 13 CO 2 and the 13 C-biogenic residues indicating nearly complete biodegradation. The parallel increase of 13 C-alanine, 13 C-glutamate and 13 CO 2 indicates that metamitron was initially biodegraded via the desamino-metamitron route suggesting its relevance in the growth metabolism. In later phases of biodegradation, the "Rhodococcus route" was indicated by the low 13 CO 2 evolution and the high relevance of the pyruvate pathway, which aims at biomolecule synthesis and seems to be related to starvation. This is a first report on the detailed degradation route of metamitron in soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dynamic changes in the structure of microbial communities in Baltic Sea coastal seawater microcosms modified by crude oil, shale oil or diesel fuel.

PubMed

Viggor, Signe; Juhanson, Jaanis; Jõesaar, Merike; Mitt, Mario; Truu, Jaak; Vedler, Eve; Heinaru, Ain

2013-08-25

The coastal waters of the Baltic Sea are constantly threatened by oil spills, due to the extensive transportation of oil products across the sea. To characterise the hydrocarbon-degrading bacterial community of this marine area, microcosm experiments on diesel fuel, crude oil and shale oil were performed. Analysis of these microcosms, using alkane monooxygenase (alkB) and 16S rRNA marker genes in PCR-DGGE experiments, demonstrated that substrate type and concentration strongly influence species composition and the occurrence of alkB genes in respective oil degrading bacterial communities. Gammaproteobacteria (particularly the genus Pseudomonas) and Alphaproteobacteria were dominant in all microcosms treated with oils. All alkB genes carried by bacterial isolates (40 strains), and 8 of the 11 major DGGE bands from the microcosms, had more than 95% sequence identity with the alkB genes of Pseudomonas fluorescens. However, the closest relatives of the majority of sequences (54 sequences from 79) of the alkB gene library from initially collected seawater DNA were Actinobacteria. alkB gene expression, induced by hexadecane, was recorded in isolated bacterial strains. Thus, complementary culture dependent and independent methods provided a more accurate picture about the complex seawater microbial communities of the Baltic Sea. Copyright © 2013 Elsevier GmbH. All rights reserved.

Effect of amorphous calcium phosphate and silver nanocomposites on dental plaque microcosm biofilms.

PubMed

Cheng, Lei; Weir, Michael D; Xu, Hockin H K; Antonucci, Joseph M; Lin, Nancy J; Lin-Gibson, Sheng; Xu, Sarah M; Zhou, Xuedong

2012-07-01

A dental composite containing amorphous calcium phosphate nanoparticles (NACP) was developed that released calcium (Ca) and phosphate (PO(4)) ions and possessed acid-neutralization capability. There has been little study on incorporation of antibacterial agents into calcium phosphate composites. The objective of this study was to investigate the effect of silver nanoparticle (NAg) mass fraction in NACP nanocomposite on mechanical properties and dental plaque microcosm biofilm for the first time. NACP nanoparticles of 116 nm were synthesized via a spray-drying technique. NAg nanoparticles were synthesized using Ag 2-ethylhexanoate and 2-(tert-butylamino)ethyl methacrylate, yielding NAg of particle size of 2.7 nm that were well-dispersed in the resin. Five NACP nanocomposites were fabricated with NAg mass fractions of 0, 0.028, 0.042, 0.088, and 0.175%, respectively. Mechanical properties of NACP nanocomposites containing 0-0.042% of NAg matched those of a commercial composite without antibacterial activity. Live/dead assay of dental plaque microcosm biofilms showed complete coverage with live bacteria on commercial composite. However, there were increasingly more dead bacteria with higher NAg content in the NACP nanocomposite. Colony-forming unit (CFU) counts for total microorganisms, total streptococci, and mutans streptococci for NACP nanocomposite with 0.042% NAg were about 1/4 those of commercial composite. Lactic acid production on NACP nanocomposite with 0.042% NAg was 1/3 that on commercial composite. In conclusion, novel NACP-NAg nanocomposites were developed which possessed good mechanical properties and potent antibacterial properties, with substantially reduced biofilm viability and lactic acid production. Hence, the NACP-NAg nanocomposites are promising for dental restorations with remineralizing and antibacterial capabilities. Copyright © 2012 Wiley Periodicals, Inc.

Effect of amorphous calcium phosphate and silver nanocomposites on dental plaque microcosm biofilms

PubMed Central

Cheng, Lei; Weir, Michael D.; Xu, Hockin H. K.; Antonucci, Joseph M.; Lin, Nancy J.; Lin-Gibson, Sheng; Xu, Sarah M.; Zhou, Xuedong

2012-01-01

A dental composite containing amorphous calcium phosphate nanoparticles (NACP) was developed that released calcium (Ca) and phosphate (PO4) ions and possessed acid-neutralization capability. There has been little study on incorporation of antibacterial agents into calcium phosphate composites. The objective of this study was to investigate the effect of silver nanoparticle (NAg) mass fraction in NACP nanocomposite on mechanical properties and dental plaque microcosm biofilm for the first time. NACP nanoparticles of 116 nm were synthesized via a spray-drying technique. NAg nanoparticles were synthesized using Ag 2-ethylhexanoate and 2-(tert-butylamino)ethyl methacrylate, yielding NAg of particle size of 2.7 nm that were well-dispersed in the resin. Five NACP nanocomposites were fabricated with NAg mass fractions of 0, 0.028, 0.042, 0.088, and 0.175%, respectively. Mechanical properties of NACP nanocomposites containing 0–0.042% of NAg matched those of a commercial composite without antibacterial activity. Live/dead assay of dental plaque microcosm biofilms showed complete coverage with live bacteria on commercial composite. However, there were increasingly more dead bacteria with higher NAg content in the NACP nanocomposite. Colony-forming unit (CFU) counts for total microorganisms, total Streptococci, and mutans Streptococci for NACP nanocomposite with 0.042% NAg were about 1/4 those of commercial composite. Lactic acid production on NACP nanocomposite with 0.042% NAg was 1/3 that on commercial composite. In conclusion, novel NACP–NAg nanocomposites were developed which possessed good mechanical properties and potent antibacterial properties, with substantially reduced biofilm viability and lactic acid production. Hence, the NACP–NAg nanocomposites are promising for dental restorations with remineralizing and antibacterial capabilities. PMID:22566464

Effects of the antibiotic enrofloxacin on the ecology of tropical eutrophic freshwater microcosms.

PubMed

Rico, Andreu; Dimitrov, Mauricio R; Van Wijngaarden, René P A; Satapornvanit, Kriengkrai; Smidt, Hauke; Van den Brink, Paul J

2014-02-01

The main objective of the present study was to assess the ecological impacts of the fluoroquinolone antibiotic enrofloxacin on the structure and functioning of tropical freshwater ecosystems. Enrofloxacin was applied at a concentration of 1, 10, 100 and 1,000 μg/L for 7 consecutive days in 600-L outdoor microcosms in Thailand. The ecosystem-level effects of enrofloxacin were monitored on five structural (macroinvertebrates, zooplankton, phytoplankton, periphyton and bacteria) and two functional (organic matter decomposition and nitrogen cycling) endpoint groups for 4 weeks after the last antibiotic application. Enrofloxacin was found to dissipate relatively fast from the water column (half-dissipation time: 11.7h), and about 11% of the applied dose was transformed into its main by-product ciprofloxacin after 24h. Consistent treatment-related effects on the invertebrate and primary producer communities and on organic matter decomposition could not be demonstrated. Enrofloxacin significantly affected the structure of leaf-associated bacterial communities at the highest treatment level, and reduced the abundance of ammonia-oxidizing bacteria and ammonia-oxidizing archaea in the sediments, with calculated NOECs of 10 and <1 μg/L, respectively. The ammonia concentration in the microcosm water significantly increased in the highest treatment level, and nitrate production was decreased, indicating a potential impairment of the nitrification function at concentrations above 100 μg/L. The results of this study suggest that environmentally relevant concentrations of enrofloxacin are not likely to result in direct or indirect toxic effects on the invertebrate and primary producer communities, nor on important microbially mediated functions such as nitrification. Copyright © 2014 Elsevier B.V. All rights reserved.

Field and microcosm experiments to evaluate the effects of agricultural Cu treatment on the density and genetic structure of microbial communities in two different soils.

PubMed

Ranjard, Lionel; Echairi, Abdelwahad; Nowak, Virginie; Lejon, David P H; Nouaïm, Rachida; Chaussod, Rémi

2006-11-01

The effects of Cu amendment on indigenous soil microorganisms were investigated in two soils, a calcareous silty clay (Ep) and a sandy soil (Au), by means of a 1-year field experiment and a two-month microcosm incubation. Cu was added as 'Bordeaux mixture' [CuSO(4), Ca(OH)(2)] at the standard rate used in viticulture (B1=16 kg Cu kg(-1) soil) and at a higher level of contamination (B3=48 kg Cu ha(-1) soil). More extractable Cu was observed in sandy soil (Au) than in silty soil (Ep). Furthermore, total Cu and Cu-EDTA declined with time in Au soil, whereas they remained stable in Ep soil. Quantitative modifications of the microflora were assessed by C-biomass measurements and qualitative modifications were assessed by the characterization of the genetic structure of bacterial and fungal communities from DNA directly extracted from the soil, using B- and F-ARISA (bacterial and fungal automated ribosomal intergenic spacer analysis). In the field study, no significant modifications were observed in C-biomass whereas microcosm incubation showed a decrease in B3 contamination only. ARISA fingerprinting showed slight but significant modifications of bacterial and fungal communities in field and microcosm incubation. These modifications were transient in all cases, suggesting a short-term effect of Cu stress. Microcosm experiments detected the microbial community modifications with greater precision in the short-term, while field experiments showed that the biological effects of Cu contamination may be overcome or hidden by pedo-climatic variations.

Treatment of synthetic textile wastewater containing dye mixtures with microcosms.

PubMed

Yaseen, Dina A; Scholz, Miklas

2018-01-01

The aim was to assess the ability of microcosms (laboratory-scale shallow ponds) as a post polishing stage for the remediation of artificial textile wastewater comprising two commercial dyes (basic red 46 (BR46) and reactive blue 198 (RB198)) as a mixture. The objectives were to evaluate the impact of Lemna minor L. (common duckweed) on the water quality outflows; the elimination of dye mixtures, organic matter, and nutrients; and the impact of synthetic textile wastewater comprising dye mixtures on the L. minor plant growth. Three mixtures were prepared providing a total dye concentration of 10 mg/l. Findings showed that the planted simulated ponds possess a significant (p < 0.05) potential for improving the outflow characteristics and eliminate dyes, ammonium-nitrogen (NH 4 -N), and nitrate-nitrogen (NO 3 -N) in all mixtures compared with the corresponding unplanted ponds. The removal of mixed dyes in planted ponds was mainly due to phyto-transformation and adsorption of BR46 with complete aromatic amine mineralisation. For ponds containing 2 mg/l of RB198 and 8 mg/l of BR46, removals were around 53%, which was significantly higher than those for other mixtures: 5 mg/l of RB198 and 5 mg/l of BR46 and 8 mg/l of RB198 and 2 mg/l of BR46 achieved only 41 and 26% removals, respectively. Dye mixtures stopped the growth of L. minor, and the presence of artificial wastewater reduced their development.

Bacterial community shift in the coastal Gulf of Mexico salt-marsh sediment microcosm in vitro following exposure to the Mississippi Canyon Block 252 oil (MC252).

PubMed

Koo, Hyunmin; Mojib, Nazia; Huang, Jonathan P; Donahoe, Rona J; Bej, Asim K

2015-08-01

In this study, we examined the responses by the indigenous bacterial communities in salt-marsh sediment microcosms in vitro following treatment with Mississippi Canyon Block 252 oil (MC252). Microcosms were constructed of sediment and seawater collected from Bayou La Batre located in coastal Alabama on the Gulf of Mexico. We used an amplicon pyrosequencing approach on microcosm sediment metagenome targeting the V3-V5 region of the 16S rRNA gene. Overall, we identified a shift in the bacterial community in three distinct groups. The first group was the early responders (orders Pseudomonadales and Oceanospirillales within class Gammaproteobacteria), which increased their relative abundance within 2 weeks and were maintained 3 weeks after oil treatment. The second group was identified as early, but transient responders (order Rhodobacterales within class Alphaproteobacteria; class Epsilonproteobacteria), which increased their population by 2 weeks, but returned to the basal level 3 weeks after oil treatment. The third group was the late responders (order Clostridiales within phylum Firmicutes; order Methylococcales within class Gammaproteobacteria; and phylum Tenericutes), which only increased 3 weeks after oil treatment. Furthermore, we identified oil-sensitive bacterial taxa (order Chromatiales within class Gammaproteobacteria; order Syntrophobacterales within class Deltaproteobacteria), which decreased in their population after 2 weeks of oil treatment. Detection of alkane (alkB), catechol (C2,3DO) and biphenyl (bph) biodegradation genes by PCR, particularly in oil-treated sediment metacommunity DNA, delineates proliferation of  the hydrocarbon degrading bacterial community. Overall, the indigenous bacterial communities in our salt-marsh sediment in vitro microcosm study responded rapidly and shifted towards members of the taxonomic groups that are capable of surviving in an MC252 oil-contaminated environment.

Interactions among buffelgrass, phenanthrene and phenanthrene-degrading bacteria in gnotobiotic microcosms.

PubMed

Robert, Francoise M; Sun, Wenhao H; Toma, Marisa; Jones, Ryan K; Tang, Chung-Shih

2008-07-15

An experiment was undertaken in gnotobiotic microcosms to determine the role of buffelgrass (Cenchrus ciliaris) and a phenanthrene-degrading bacterium (strain PM600) in the degradation of phenanthrene. The Gram-negative bacterium was identified as a Sphingomonas sp. by 16S rRNA gene sequence analysis and as S. paucimobilis by biochemical tests (API 20 NE strips). Its yellow pigment corresponded to nostoxanthin and its cellular fatty acids were typical of the genus Sphingomonas. Moreover, it was devoid of lipopolysaccharides. Strain PM600 was tested for growth on mineral medium supplemented with No. 2 diesel, hexadecane, mineral oil, pristane, phenanthrene, and pyrene as single carbon sources. It was capable of utilizing phenanthrene only. In the gnotobiotic microcosms silica sand was either or not supplemented with 150 mg of phenanthrene kg(-1) sand, inoculated with strain PM600, and planted to sterile young seedlings of buffelgrass. After 28 days, 67% of the reduction of the phenanthrene concentration was assigned to degradation by the bacterium and ca. 20% to abiotic factors. No statistically significant effect of the young buffelgrass was found. In the absence of phenanthrene, the bacterial population significantly increased in the rhizosphere of buffelgrass. However, in the presence of buffelgrass and phenanthrene, the bacterial population preferentially responded to phenanthrene. The growth of buffelgrass was severely curtailed by phenanthrene in the absence of the bacterium. However, strain PM600 effectively protected buffelgrass against the phytotoxicity of phenanthrene.

[Dental plaque microcosm biofilm behavior on a resin composite incorporated with nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt].

PubMed

Junling, Wu; Qiang, Zhang; Ruinan, Sun; Ting, Zhu; Jianhua, Ge; Chuanjian, Zhou

2015-12-01

To develop a resin composite incorporated with nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt, and to measure its effect on human dental plaque microcosm biofilm. A novel nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt was synthesized according to methods introduced in previous research. Samples of the novel nano-antibacterial inorganic fillers were modified by a coupling agent and then added into resin composite at 0%, 5%, 10%, 15% or 20% mass fractions; 0% composite was used as control. A flexural test was used to measure resin composite mechanical properties. Results showed that a dental plaque microcosm biofilm model with human saliva as inoculum was formed. Colony-forming unit (CFU) counts, lactic acid production, and live/dead assay of biofilm on the resin composite were calculated to test the effect of the resin composite on human dental plaque microcosm biofilm. The incorporation of nano-antibacterial inorganic fillers with as much as 15% concentration into the resin composite showed no adverse effect on the mechanical properties of the resin composite (P > 0.05). Resin composite containing 5% or more nano-antibacterial inorganic fillers significantly inhibited the metabolic activity of dental plaque microcosm biofilm, suggesting its strong antibacterial potency (P < 0.05). This novel resin composite exhibited a strong antibacterial property upon the addition of up to 5% nano-antibacterial inorganic fillers, thereby leading to effective caries inhibition in dental application.

Protein relative abundance patterns associated with sucrose-induced dysbiosis are conserved across taxonomically diverse oral microcosm biofilm models of dental caries.

PubMed

Rudney, Joel D; Jagtap, Pratik D; Reilly, Cavan S; Chen, Ruoqiong; Markowski, Todd W; Higgins, LeeAnn; Johnson, James E; Griffin, Timothy J

2015-12-19

The etiology of dental caries is multifactorial, but frequent consumption of free sugars, notably sucrose, appears to be a major factor driving the supragingival microbiota in the direction of dysbiosis. Recent 16S rRNA-based studies indicated that caries-associated communities were less diverse than healthy supragingival plaque but still displayed considerable taxonomic diversity between individuals. Metagenomic studies likewise have found that healthy oral sites from different people were broadly similar with respect to gene function, even though there was an extensive individual variation in their taxonomic profiles. That pattern may also extend to dysbiotic communities. In that case, shifts in community-wide protein relative abundance might provide better biomarkers of dysbiosis that can be achieved through taxonomy alone. In this study, we used a paired oral microcosm biofilm model of dental caries to investigate differences in community composition and protein relative abundance in the presence and absence of sucrose. This approach provided large quantities of protein, which facilitated deep metaproteomic analysis. Community composition was evaluated using 16S rRNA sequencing and metaproteomic approaches. Although taxonomic diversity was reduced by sucrose pulsing, considerable inter-subject variation in community composition remained. By contrast, functional analysis using the SEED ontology found that sucrose induced changes in protein relative abundance patterns for pathways involving glycolysis, lactate production, aciduricity, and ammonia/glutamate metabolism that were conserved across taxonomically diverse dysbiotic oral microcosm biofilm communities. Our findings support the concept of using function-based changes in protein relative abundance as indicators of dysbiosis. Our microcosm model cannot replicate all aspects of the oral environment, but the deep level of metaproteomic analysis it allows makes it suitable for discovering which proteins are

BIODEGRADATION OF A PAH MIXTURE BY NATIVE SUBSURFACE MICROBIOTA. (R828770)

EPA Science Inventory

Laboratory microcosm studies were conducted to estimate biodegradation rates for a mixture of five polycyclic aromatic hydrocarbon compounds (PAHs). Static microcosms were assembled using soil samples from two locations collected at a No. 2 fuel oil-contaminated site in the At...

BIODEGRADATION OF A PAH MIXTURE BY NATIVE SUBSURFACE MICROBIOTA. (R828770C004)

EPA Science Inventory

Laboratory microcosm studies were conducted to estimate biodegradation rates for a mixture of five polycyclic aromatic hydrocarbon compounds (PAHs). Static microcosms were assembled using soil samples from two locations collected at a No. 2 fuel oil-contaminated site in the At...

A Natal Microcosm

NASA Technical Reports Server (NTRS)

2004-01-01

In the quest to better understand the birth of stars and the formation of new worlds, astronomers have used NASA's Spitzer Space Telescope to examine the massive stars contained in a cloudy region called Sharpless 140. This cloud is a fascinating microcosm of a star-forming region since it exhibits, within a relatively small area, all of the classic manifestations of stellar birth.

Sharpless 140 lies almost 3000 light-years from Earth in the constellation Cepheus. At its heart is a cluster of three deeply embedded young stars, which are each several thousand times brighter than the Sun. Though they are strikingly visible in this image from Spitzer's infrared array camera, they are completely obscured in visible light, buried within the core of the surrounding dust cloud.

The extreme youth of at least one of these stars is indicated by the presence of a stream of gas moving at high velocities. Such outflows are signatures of the processes surrounding a star that is still gobbling up material as part of its formation.

The bright red bowl, or arc, seen in this image traces the outer surface of the dense dust cloud encasing the young stars. This arc is made up primarily of organic compounds called polycyclic aromatic hydrocarbons, which glow on the surface of the cloud. Ultraviolet light from a nearby bright star outside of the image is 'eating away' at these molecules. Eventually, this light will destroy the dust envelope and the masked young stars will emerge.

This false-color image was taken on Oct. 11, 2003 and is composed of photographs obtained at four wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red).

A Natal Microcosm

NASA Image and Video Library

2004-05-11

In the quest to better understand the birth of stars and the formation of new worlds, astronomers have used NASA's Spitzer Space Telescope to examine the massive stars contained in a cloudy region called Sharpless 140. This cloud is a fascinating microcosm of a star-forming region since it exhibits, within a relatively small area, all of the classic manifestations of stellar birth. Sharpless 140 lies almost 3000 light-years from Earth in the constellation Cepheus. At its heart is a cluster of three deeply embedded young stars, which are each several thousand times brighter than the Sun. Though they are strikingly visible in this image from Spitzer's infrared array camera, they are completely obscured in visible light, buried within the core of the surrounding dust cloud. The extreme youth of at least one of these stars is indicated by the presence of a stream of gas moving at high velocities. Such outflows are signatures of the processes surrounding a star that is still gobbling up material as part of its formation. The bright red bowl, or arc, seen in this image traces the outer surface of the dense dust cloud encasing the young stars. This arc is made up primarily of organic compounds called polycyclic aromatic hydrocarbons, which glow on the surface of the cloud. Ultraviolet light from a nearby bright star outside of the image is "eating away" at these molecules. Eventually, this light will destroy the dust envelope and the masked young stars will emerge. This false-color image was taken on Oct. 11, 2003 and is composed of photographs obtained at four wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red). http://photojournal.jpl.nasa.gov/catalog/PIA05878

Marine Microcosm Experiments on Effects of Copper and Tributylin-Based Antifouling Paint Leachates

DTIC Science & Technology

1988-06-01

consumers in HliOrg microcosms were probably the thick carpets of green algae ( Cladophora socialis) that developed in those tanks during leachate and...and bottom substrate in the SPG-4 tanks were dominated by a low-diversity community composed primarily of Cladophora socialis, a filamentous green...coverage and diversity of species after 4 weeks of’ exposure. Moderate to thick growths of filamentous green algae ( Cladophora socialis) covered with

Uncovering stability mechanisms in microbial ecosystems - combining microcosm experiments, computational modelling and ecological theory in a multidisciplinary approach

NASA Astrophysics Data System (ADS)

Worrich, Anja; König, Sara; Banitz, Thomas; Centler, Florian; Frank, Karin; Kästner, Matthias; Miltner, Anja; Thullner, Martin; Wick, Lukas

2015-04-01

Although bacterial degraders in soil are commonly exposed to fluctuating environmental conditions, the functional performance of the biodegradation processes can often be maintained by resistance and resilience mechanisms. However, there is still a gap in the mechanistic understanding of key factors contributing to the stability of such an ecosystem service. Therefore we developed an integrated approach combining microcosm experiments, simulation models and ecological theory to directly make use of the strengths of these disciplines. In a continuous interplay process, data, hypotheses, and central questions are exchanged between disciplines to initiate new experiments and models to ultimately identify buffer mechanisms and factors providing functional stability. We focus on drying and rewetting-cycles in soil ecosystems, which are a major abiotic driver for bacterial activity. Functional recovery of the system was found to depend on different spatial processes in the computational model. In particular, bacterial motility is a prerequisite for biodegradation if either bacteria or substrate are heterogeneously distributed. Hence, laboratory experiments focussing on bacterial dispersal processes were conducted and confirmed this finding also for functional resistance. Obtained results will be incorporated into the model in the next step. Overall, the combination of computational modelling and laboratory experiments identified spatial processes as the main driving force for functional stability in the considered system, and has proved a powerful methodological approach.

Study on the effects of near-future ocean acidification on marine yeasts: a microcosm approach

NASA Astrophysics Data System (ADS)

Krause, Evamaria; Wichels, Antje; Erler, René; Gerdts, Gunnar

2013-12-01

Marine yeasts play an important role in biodegradation and nutrient cycling and are often associated with marine flora and fauna. They show maximum growth at pH levels lower than present-day seawater pH. Thus, contrary to many other marine organisms, they may actually profit from ocean acidification. Hence, we conducted a microcosm study, incubating natural seawater from the North Sea at present-day pH (8.10) and two near-future pH levels (7.81 and 7.67). Yeasts were isolated from the initial seawater sample and after 2 and 4 weeks of incubation. Isolates were classified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and representative isolates were identified by partial sequencing of the large subunit rRNA gene. From the initial seawater sample, we predominantly isolated a yeast-like filamentous fungus related to Aureobasidium pullulans, Cryptococcus sp., Candida sake, and various cold-adapted yeasts. After incubation, we found more different yeast species at near-future pH levels than at present-day pH. Yeasts reacting to low pH were related to Leucosporidium scottii, Rhodotorula mucilaginosa, Cryptococcus sp., and Debaryomyces hansenii. Our results suggest that these yeasts will benefit from seawater pH reductions and give a first indication that the importance of yeasts will increase in a more acidic ocean.

Microcosmic mechanisms for protein incomplete release and stability of various amphiphilic mPEG-PLA microspheres.

PubMed

Wei, Yi; Wang, Yu Xia; Wang, Wei; Ho, Sa V; Qi, Feng; Ma, Guang Hui; Su, Zhi Guo

2012-10-02

The microcosmic mechanisms of protein (recombinant human growth hormone, rhGH) incomplete release and stability from amphiphilic poly(monomethoxypolyethylene glycol-co-D,L-lactide) (mPEG-PLA, PELA) microspheres were investigated. PELA with different hydrophilicities (PELA-1, PELA-2, and PELA-3) based on various ratios of mPEG to PLA were employed to prepare microspheres exhibiting a narrow size distribution using a combined double emulsion and premix membrane emulsification method. The morphology, rhGH encapsulation efficiency, in vitro release profile, and rhGH stability of PELA microspheres during the release were characterized and compared in detail. It was found that increasing amounts of PLA enhanced the encapsulation efficiency of PELA microspheres but reduced both the release rate of rhGH and its stability. Contact angle, atomic force microscope (AFM), and quartz crystal microbalance with dissipation (QCM-D) techniques were first combined to elucidate the microcosmic mechanism of incomplete release by measuring the hydrophilicity of the PELA film and its interaction with rhGH. In addition, the pH change within the microsphere microenvironment was monitored by confocal laser scanning microscopy (CLSM) employing a pH-sensitive dye, which clarified the stability of rhGH during the release. These results suggested that PELA hydrophilicity played an important role in rhGH incomplete release and stability. Thus, the selection of suitable hydrophilic polymers with adequate PEG lengths is critical in the preparation of optimum protein drug sustained release systems. This present work is a first report elucidating the microcosmic mechanisms responsible for rhGH stability and its interaction with the microspheres. Importantly, this research demonstrated the application of promising new experimental methods in investigating the interaction between biomaterials and biomacromolecules, thus opening up a range of exciting potential applications in the biomedical field

[Effect on the respiration of bacteria in microcosm by the disinfectant of chlorine].

PubMed

Lu, Yi; Wang, Ying; Ren, Lijun; Wang, Lin

2007-03-01

To observe respiratory volume of bacteria as the physiology activity index to evaluate the effect of sodium hypochlorite (NaClO) on the microenvironment. The water and soil from Wuhan Muoshui Lake were selected as research object. Man-made microcosms were designed and constructed. The sodium hypochlorite was put into the microcosms every 24 hour for 13 days. The bacteria respiratory volume and the general bacterial population were observed. The results showed that the bacteria in the low-dose disinfectant were stimulated and its respiration volumes were increased in the beginning of the experiment. But several days later, the bacteria were inhibited or killed predominantly which led to the decrease of its respiration volumes. In high-dose group, the bacteria were killed obviously in the beginning and their respiration volumes decreased immediately. After the disinfectant was given up, the respiratory volume resumed gradually to the initial condition. This change process accorded with the general bacterial population as a whole. The respiratory volume of bacteria was related with the dose of disinfectant. The change of the respiratory volume of bacteria was related with the dose of sodium hypochlorite. The disinfectant effect on the metabolic activity of microorganism would be lighter if it under the dose 10 mg/L.

Resuscitation by Ferrioxamine E of Stressed Salmonella enterica Serovar Typhimurium from Soil and Water Microcosms

PubMed Central

Reissbrodt, R.; Heier, H.; Tschäpe, H.; Kingsley, R. A.; Williams, P. H.

2000-01-01

Storage of Salmonella enterica serovar Typhimurium strains in soil and water microcosms resulted in loss of culturability on standard plating media. Prior incubation in buffered peptone water supplemented with ferrioxamine E markedly extended the time that bacteria were recoverable by plating, except in the case of mutants deficient in ferrioxamine E uptake. PMID:10966440

Biodegradation potential of MTBE in a fractured chalk aquifer under aerobic conditions in long-term uncontaminated and contaminated aquifer microcosms.

PubMed

Shah, Nadeem W; Thornton, Steven F; Bottrell, Simon H; Spence, Michael J

2009-01-26

metabolites occurred. The availability of dissolved O2 did not affect MTBE biodegradation significantly, with similar MTBE biodegradation behaviour and rates down to ca. 0.7 mg/L dissolved O2 concentration. The results indicate that aerobic MTBE biodegradation could be significant in the plume fringe, during mixing of the contaminant plume and uncontaminated groundwater and that, relative to the plume migration, aerobic biodegradation is important for MTBE attenuation. Moreover, should the groundwater dissolved O2 concentration fall to zero such that MTBE biodegradation was inhibited, an engineered approach to enhance in situ bioremediation could supply O2 at relatively low levels (e.g. 2-3 mg/L) to effectively stimulate MTBE biodegradation, which has significant practical advantages. The study shows that aerobic MTBE biodegradation can occur at environmentally significant rates in this aquifer, and that long-term microcosm experiments (100s days) may be necessary to correctly interpret contaminant biodegradation potential in aquifers to support site management decisions.

Microbial composition in microcosms amended with natural and mineral fertilizers under different water regimes

NASA Astrophysics Data System (ADS)

Brad, Traian; Chiriac, Cecilia; Szekeres, Edina; Coman, Cristian; Rudi, Knut; Sandor, Mignon

2017-04-01

Twenty microcosm enclosures containing two types of soil (i.e. a rich Chernozemic and a poorer soil) were fertilized with mineral (NPK-complex) and organic (Gülle, manure and a green fertilizer) materials and placed under dry and wet water regimes. After 10, 20 and 30 days of the experiment, soil samples were analyzed for the structure and composition of microbial communities using next generation sequencing techniques (Illumina) and statistical analysis. The differences between bacteria communities in different soil types, and in different fertilization and hydric treatments were analyzed using quantitative phylogenetic distances and the ANOSIM test. The two types of soil especially selected for the structure of microbial communities, while moisture and the type of fertilizer appeared to have a smaller influence on microbial diversity in microcosms. The alpha-diversity indices (species richness, evenness and phylogenetic diversity) had higher values for the poorer soil compared to the rich Chernozemic soil. For both soil types, the highest bacteria diversity values were obtained after fertilization with manure. The microbial communities in the analyzed soils were complex and dominated by sequences belonging to Actinobacteria, Proteobacteria, Acidobacteria and Firmicutes.

Effect of vegetation removal and water table drawdown on the non-methane biogenic volatile organic compound emissions in boreal peatland microcosms

NASA Astrophysics Data System (ADS)

Faubert, Patrick; Tiiva, Päivi; Rinnan, Åsmund; Räty, Sanna; Holopainen, Jarmo K.; Holopainen, Toini; Rinnan, Riikka

2010-11-01

Biogenic volatile organic compound (BVOC) emissions are important in the global atmospheric chemistry and their feedbacks to global warming are uncertain. Global warming is expected to trigger vegetation changes and water table drawdown in boreal peatlands, such changes have only been investigated on isoprene emission but never on other BVOCs. We aimed at distinguishing the BVOCs released from vascular plants, mosses and peat in hummocks (dry microsites) and hollows (wet microsites) of boreal peatland microcosms maintained in growth chambers. We also assessed the effect of water table drawdown (-20 cm) on the BVOC emissions in hollow microcosms. BVOC emissions were measured from peat samples underneath the moss surface after the 7-week-long experiment to investigate whether the potential effects of vegetation and water table drawdown were shown. BVOCs were sampled using a conventional chamber method, collected on adsorbent and analyzed with GC-MS. In hummock microcosms, vascular plants increased the monoterpene emissions compared with the treatment where all above-ground vegetation was removed while no effect was detected on the sesquiterpenes, other reactive VOCs (ORVOCs) and other VOCs. Peat layer from underneath the surface with intact vegetation had the highest sesquiterpene emissions. In hollow microcosms, intact vegetation had the highest sesquiterpene emissions. Water table drawdown decreased monoterpene and other VOC emissions. Specific compounds could be closely associated to the natural/lowered water tables. Peat layer from underneath the surface of hollows with intact vegetation had the highest emissions of monoterpenes, sesquiterpenes and ORVOCs whereas water table drawdown decreased those emissions. The results suggest that global warming would change the BVOC emission mixtures from boreal peatlands following changes in vegetation composition and water table drawdown.

Anaerobic oxidation of ethene coupled to sulfate reduction in microcosms and enrichment cultures.

PubMed

Fullerton, Heather; Crawford, Michael; Bakenne, Ademola; Freedman, David L; Zinder, Stephen H

2013-01-01

Ethene is considered recalcitrant under anaerobic conditions, but biological reduction to ethane and oxidation to CO2 have been reported; however, little is known about these processes or the organisms carrying them out. In this report we describe sulfate dependent ethene consumption in microcosms prepared with sediments from a freshwater canal. A first dose of 0.6 mmol/L ethene was consumed within 77 days, and a second dose was largely consumed twelve days later. Material from this microcosm was transferred into growth medium with ethene as the only electron donor (except for trace amounts of vitamins) and sulfate as the electron acceptor. Four doses of ethene were consumed at increasing rates, and the cultures have been transferred at least eight times in this medium. Conversion of [(14)C]ethene primarily to (14)CO2 was demonstrated in fifth and sixth generation cultures, as well as production of sulfide in other cultures, confirming the ethene/sulfate couple. Ovoid cells 1-2 μm in diameter were found in cultures containing ethene and sulfate, and quantitative PCR showed large increases in bacterial 16S rRNA gene copy number. Over half of a 16S rRNA gene clone library from a sixth-generation culture was a phylotype with a sequence ca. 90% identical with a clade of Deltaproteobacteria that includes Desulfovirga adipica and several Syntrophobacter spp. These studies have solidified the concept that deficits in mass balances for chloroethene fate in sulfate reducing zones of contaminated groundwater sites may be due to ethene oxidation, and suggest a unique phylotype is involved in this process.

Effects of transgenic Bt rice on growth, reproduction, and superoxide dismutase activity of Folsomia candida (Collembola: Isotomidae) in laboratory studies.

PubMed

Bai, Yaoyu; Yan, Ruihong; Ke, Xin; Ye, Gongyin; Huang, Fangneng; Luo, Yongming; Cheng, Jiaan

2011-12-01

Transgenic rice expressing Bacillus thuringiensis (Bt) CrylAb protein is expected to be commercialized in China in the near future. The use of Bt rice for controlling insect pests sparks intensive debates regarding its biosafety. Folsomia candida is an euedaphic species and is often used as a "standard" test organism in assessing effects of environmental pollutants on soil organisms. In this study, growth, development, reproduction, and superoxide dismutase activity (SOD) of F. candida were investigated in the laboratory for populations reared on leaf tissue or leaf-soil mixtures of two CrylAb rice lines and a non-Bt rice isoline. Two independent tests were performed: 1) a 35-d test using petri dishes containing yeast diet (positive control) or fresh rice leaf tissue, and 2) a 28-d test in soil-litter microcosms containing yeast or a mixture of soil and rice leaf tissue. Biological parameters measured in both tests were number of progeny production, population growth rate, and SOD activity. For the petri dish test, data measured also included insect body length and number of exuviation. There were no significant differences between the populations reared on Bt and non-Bt rice leaf tissue in all measured parameters in both tests and for both Bt rice lines, suggesting no significant effects of the CrylAb protein in Bt rice on F. candida in the laboratory studies. Results of this study should add additional biosafety proofs for use of Bt rice to manage rice pests in China.

Effects of the phenylurea herbicide diuron on natural riverine microbial communities in an experimental study.

PubMed

Pesce, Stéphane; Fajon, Céline; Bardot, Corinne; Bonnemoy, Frédérique; Portelli, Christophe; Bohatier, Jacques

2006-07-20

The effects of the phenylurea herbicide diuron (10 microgl(-1)) on natural riverine microbial communities were investigated using a three-week laboratory microcosm study. During the first six days, a latency period was observed both in the algal and the bacterial communities despite favorable abiotic conditions and independently of diuron exposure. From the second week, an intense algal bloom (chlorophyll a concentrations and cell abundances) was observed in the uncontaminated microcosms but not in the treated microcosms. The bloom stimulated the bacterial community and led to an increase in heterotrophic bacterial production ([3H]thymidine incorporation), activity (CTC reduction) and cell abundance. In parallel, shifts in bacterial community composition were recorded by polymerase chain reaction (PCR)-temporal temperature gradient gel electrophoresis (TTGE) analysis, whereas no major variation was detected using the fluorescent in situ hybridization (FISH) method. In the treated microcosms, the diuron acted not by damaging the initial communities but by inhibiting the algal bloom and indirectly maintaining constant bacterial conditions throughout the experiment. These inhibitory effects, which were recorded in terms of abundance, activity and diversity, suggest that exposure to diuron can decrease the recovery capacities of microbial communities and delay the resumption of an efficient microbial food web despite favorable environmental conditions.

Microbiological and Hydrogeochemical Controls on Anaerobic Biodegradation of Petroleum Hydrocarbons: Case Study from Fort McCoy, WI

NASA Astrophysics Data System (ADS)

Schreiber, M. E.; Zwolinski, M. D.; Taglia, P. J.; Bahr, J. M.; Hickey, W. J.

2001-05-01

We are investigating the role of anaerobic processes that control field-scale BTEX loss using a variety of experimental and numerical techniques. Tracer tests, laboratory microcosms, and in situ microcosms (ISMs) were designed to examine BTEX biodegradation under intrinsic and enhanced anaerobic conditions in a BTEX plume at Fort McCoy, WI. In the tracer tests, addition of nitrate resulted in loss of toluene, ethylbenzene, and m, p-xylenes but not benzene. Laboratory microcosm and ISM experiments confirmed that nitrate addition is not likely to enhance benzene biodegradation at the site. Excess nitrate losses were observed in both field and laboratory experiments, indicating that reliance on theoretical stoichiometric equations to estimate contaminant mass losses should be re-evaluated. To examine changes in microbial community during biodegradation of BTEX under enhanced nitrate-reducing conditions, DNA was extracted from laboratory microcosm sediment, the 16S-rRNA gene was amplified using eubacterial primers, and products were separated by denaturing gradient gel electrophoresis. Banding patterns suggest that nitrate caused more of a community change than BTEX. These data suggest that nitrate plays an important role in microbial population selection. Numerical simulations were conducted to simulate the evolution of the BTEX plume and to quantify BTEX losses due to intrinsic and nitrate-enhanced biodegradation. Results suggest that the majority of intrinsic BTEX mass loss has occurred under aerobic and iron-reducing conditions. Due to depletion of solid-phase Fe(III) over time, however, future BTEX losses under iron-reducing conditions will decrease, and methanogenesis will play an increasingly important role in controlling biodegradation. The simulations also suggest that although nitrate addition will decrease TEX concentrations, source removal with intrinsic biodegradation is likely the most effective treatment method for the site.

Biodegradation of organic chemicals in soil/water microcosms system: Model development

USGS Publications Warehouse

Liu, L.; Tindall, J.A.; Friedel, M.J.; Zhang, W.

2007-01-01

The chemical interactions of hydrophobic organic contaminants with soils and sediments may result in strong binding and slow subsequent release rates that significantly affect remediation rates and endpoints. In order to illustrate the recalcitrance of chemical to degradation on sites, a sorption mechanism of intraparticle sequestration was postulated to operate on chemical remediation sites. Pseudo-first order sequestration kinetics is used in the study with the hypothesis that sequestration is an irreversibly surface-mediated process. A mathematical model based on mass balance equations was developed to describe the fate of chemical degradation in soil/water microcosm systems. In the model, diffusion was represented by Fick's second law, local sorption-desorption by a linear isotherm, irreversible sequestration by a pseudo-first order kinetics and biodegradation by Monod kinetics. Solutions were obtained to provide estimates of chemical concentrations. The mathematical model was applied to a benzene biodegradation batch test and simulated model responses correlated well compared to measurements of biodegradation of benzene in the batch soil/water microcosm system. A sensitivity analysis was performed to assess the effects of several parameters on model behavior. Overall chemical removal rate decreased and sequestration increased quickly with an increase in the sorption partition coefficient. When soil particle radius, a, was greater than 1 mm, an increase in radius produced a significant decrease in overall chemical removal rate as well as an increase in sequestration. However, when soil particle radius was less than 0.1 mm, an increase in radius resulted in small changes in the removal rate and sequestration. As pseudo-first order sequestration rate increased, both chemical removal rate and sequestration increased slightly. Model simulation results showed that desorption resistance played an important role in the bioavailability of organic chemicals in porous

Group as social microcosm: Within-group interpersonal style is congruent with outside group relational tendencies.

PubMed

Goldberg, Simon B; Hoyt, William T

2015-06-01

The notion that individuals' interpersonal behaviors in the context of therapy reflects their interpersonal behaviors outside of therapy is a fundamental hypothesis underlying numerous systems of psychotherapy. The social microcosm hypothesis, in particular, claims the interpersonal therapy group becomes a reflection of group members' general tendencies, and can thus be used as information about members' interpersonal functioning as well as an opportunity for learning and behavior change. The current study tested this hypothesis using data drawn from 207 individuals participating in 22 interpersonal process groups. Ratings were made on 2 key interpersonal domains (Dominance and Affiliation) at baseline and at Weeks 2, 5, and 8 of the group. Two-level multilevel models (with participants nested within groups) were used to account for the hierarchical structure, and the social relations model (SRM; Kenny, 1994) was used to estimate peer ratings (target effects in SRM) unconfounded with rater bias. Participants showed consensus at all time points during the interpersonal process groups on one another's levels of dominance and affiliation. In addition, self- and peer ratings were stable across time and correlated with one another. Importantly, self-ratings made prior to group significantly predicted ratings (self- and peer) made within the group, with effect sizes within the medium range. Taken together, these results provide robust support for the social microcosm hypothesis and the conjecture that interpersonal style within-group therapy is reflective of broader interpersonal tendencies. (c) 2015 APA, all rights reserved).

Detection by denaturing gradient gel electrophoresis of ammonia-oxidizing bacteria in microcosms of crude oil-contaminated mangrove sediments.

PubMed

dos Santos, A C F; Marques, E L S; Gross, E; Souza, S S; Dias, J C T; Brendel, M; Rezende, R P

2012-01-27

Currently, the effect of crude oil on ammonia-oxidizing bacterium communities from mangrove sediments is little understood. We studied the diversity of ammonia-oxidizing bacteria in mangrove microcosm experiments using mangrove sediments contaminated with 0.1, 0.5, 1, 2, and 5% crude oil as well as non-contaminated control and landfarm soil from near an oil refinery in Camamu Bay in Bahia, Brazil. The evolution of CO(2) production in all crude oil-contaminated microcosms showed potential for mineralization. Cluster analysis of denaturing gradient gel electrophoresis-derived samples generated with primers for gene amoA, which encodes the functional enzyme ammonia monooxygenase, showed differences in the sample contaminated with 5% compared to the other samples. Principal component analysis showed divergence of the non-contaminated samples from the 5% crude oil-contaminated sediment. A Venn diagram generated from the banding pattern of PCR-denaturing gradient gel electrophoresis was used to look for operational taxonomic units (OTUs) in common. Eight OTUs were found in non-contaminated sediments and in samples contaminated with 0.5, 1, or 2% crude oil. A Jaccard similarity index of 50% was found for samples contaminated with 0.1, 0.5, 1, and 2% crude oil. This is the first study that focuses on the impact of crude oil on the ammonia-oxidizing bacterium community in mangrove sediments from Camamu Bay.

Survival, growth, and body residues of hyalella azteca (Saussure) exposed to fipronil contaminated sediments from non-vegetated and vegetated microcosms.

PubMed

Kröger, Robert; Lizotte, Richard E; Moore, Matthew T

2009-09-01

We assessed chronic effects of fipronil and metabolite contaminated sediments from non-vegetated and Thallia dealbata vegetated wetland microcosms on Hyalella azteca during wet and dry exposures. Mean sediment concentrations (ng g(-1)) ranged from 0.72-1.26, 0.01-0.69, 0.07-0.23, and 0.49-7.87 for fipronil, fipronil-sulfide, fipronil-sulfone, and fipronil-desulfinyl, respectively. No significant differences in animal survival or growth were observed between non-vegetated and vegetated microcosms during wet or dry exposures. Mean animal body residue concentrations (ng g(-1)) ranged from 28.4-77.6, 0-30.7, and 8.3-43.8 for fipronil, fipronil-sulfide, and fipronil-sulfone. Fipronil-desulfinyl was not detected in any animal samples.

Effect of quaternary ammonium and silver nanoparticle-containing adhesives on dentin bond strength and dental plaque microcosm biofilms

PubMed Central

Zhang, Ke; Melo, Mary Anne S.; Cheng, Lei; Weir, Michael D.; Bai, Yuxing; Xu, Hockin H. K.

2012-01-01

Objectives Antibacterial bonding agents are promising to hinder the residual and invading bacteria at the tooth-restoration interfaces. The objectives of this study were to develop an antibacterial bonding agent by incorporation of quaternary ammonium dimethacrylate (QADM) and nanoparticles of silver (NAg), and to investigate the effect of QADM-NAg adhesive and primer on dentin bond strength and plaque microcosm biofilm response for the first time. Methods Scotchbond Multi-Purpose adhesive and primer were used as control. Experimental adhesive and primer were made by adding QADM and NAg into control adhesive and primer. Human dentin shear bond strengths were measured (n = 10). A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate biofilm metabolic activity, colony-forming unit (CFU) counts, lactic acid production, and live/dead staining assay (n = 6). Results Adding QADM and NAg into adhesive and primer did not compromise the dentin shear bond strength which ranged from 30 to 35 MPa (p > 0.1). Scanning electron microscopy (SEM) examinations revealed numerous resin tags, which were similar for the control and the QADM and NAg groups. Adding QADM or NAg markedly reduced the biofilm viability, compared to adhesive control. QADM and NAg together in the adhesive had a much stronger antibacterial effect than using each agent alone (p < 0.05). Adding QADM and NAg in both adhesive and primer had the strongest antibacterial activity, reducing metabolic activity, CFU, and lactic acid by an order of magnitude, compared to control. Significance Without compromising dentin bond strength and resin tag formation, the QADM and NAg containing adhesive and primer achieved strong antibacterial effects against microcosm biofilms for the first time. QADM-NAg adhesive and primer are promising to combat residual bacteria in tooth cavity and invading bacteria at the margins, thereby to inhibit secondary caries. QADM and NAg incorporation may have a

Effect of quaternary ammonium and silver nanoparticle-containing adhesives on dentin bond strength and dental plaque microcosm biofilms.

PubMed

Zhang, Ke; Melo, Mary Anne S; Cheng, Lei; Weir, Michael D; Bai, Yuxing; Xu, Hockin H K

2012-08-01

Antibacterial bonding agents are promising to hinder the residual and invading bacteria at the tooth-restoration interfaces. The objectives of this study were to develop an antibacterial bonding agent by incorporation of quaternary ammonium dimethacrylate (QADM) and nanoparticles of silver (NAg), and to investigate the effect of QADM-NAg adhesive and primer on dentin bond strength and plaque microcosm biofilm response for the first time. Scotchbond Multi-Purpose adhesive and primer were used as control. Experimental adhesive and primer were made by adding QADM and NAg into control adhesive and primer. Human dentin shear bond strengths were measured (n = 10). A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate biofilm metabolic activity, colony-forming unit (CFU) counts, lactic acid production, and live/dead staining assay (n = 6). Adding QADM and NAg into adhesive and primer did not compromise the dentin shear bond strength which ranged from 30 to 35MPa (p>0.1). Scanning electron microscopy (SEM) examinations revealed numerous resin tags, which were similar for the control and the QADM and NAg groups. Adding QADM or NAg markedly reduced the biofilm viability, compared to adhesive control. QADM and NAg together in the adhesive had a much stronger antibacterial effect than using each agent alone (p<0.05). Adding QADM and NAg in both adhesive and primer had the strongest antibacterial activity, reducing metabolic activity, CFU, and lactic acid by an order of magnitude, compared to control. Without compromising dentin bond strength and resin tag formation, the QADM and NAg containing adhesive and primer achieved strong antibacterial effects against microcosm biofilms for the first time. QADM-NAg adhesive and primer are promising to combat residual bacteria in tooth cavity and invading bacteria at the margins, thereby to inhibit secondary caries. QADM and NAg incorporation may have a wide applicability to other dental bonding

In situ and laboratory studies on the fate of specific organic compounds in an anaerobic landfill leachate plume, 1. Experimental conditions and fate of phenolic compounds

NASA Astrophysics Data System (ADS)

Nielsen, Per H.; Albrechtsen, Hans-Jørgen; Heron, Gorm; Christensen, Thomas H.

1995-11-01

The transformation of specific organic compounds was investigated by in situ and laboratory experiments in an anaerobic landfill leachate pollution plume at four different distances from the landfill. This paper presents the experimental conditions in the in situ microcosm and laboratory batch microcosm experiments performed and the results on the fate of 7 phenolic compounds. Part 2 of this series of papers, also published in this issue, presents the results on the fate of 8 aromatic compounds and 4 chlorinated aliphatic compounds. The redox conditions in the plume were characterized as methanogenic, Fe(III)-reducing and NO 3--reducing by the redox sensitive species present in groundwater and sediment and by bioassays. With a few exceptions the aquifer redox conditions were maintained throughout the experiments as monitored by redox sensitive species present in groundwater during the experiments, by redox sensitive species present in the sediment after the experiments and by bioassays performed after the experiments. Transformation of nitrophenol was very fast close to the landfill in strongly reducing conditions, while transformation was slower in the more oxidized part of the plume. Lag phases for the nitrophenols were short (maximum 10 days). Phenol was only transformed in the more distant part of the plume in experiments where NO 3-, Fe(III) and Mn(IV) reduction was dominant. Lag phases for phenol were either absent or lasted up to 2 months. Dichlorophenols were only transformed in experiments representing strongly reducing, presumably methanogenic, redox conditions close to the landfill after lag phases of up to 3 months. Transformation of o-cresol was not observed in any of the experiments throughout the plume. Generally, there was good accordance between the results obtained by in situ and laboratory experiments, both concerning redox conditions and the fate of the phenolic compounds. However, for phenol and 2,4-dichlorophenol, transformation was observed

Chlorodifluoroacetic acid fate and toxicity to the macrophytes Lemna gibba, Myriophyllum spicatum, and Myriophyllum sibiricum in aquatic microcosms.

PubMed

Hanson, M L; Sibley, P K; Mabury, S A; Muir, D C; Solomon, K R

2001-12-01

Chlorodifluoroacetic acid (CDFA) is a novel haloacetic acid (HAA) and has been recently documented in aquatic systems. It is a suspected degradation product of the refrigerants 1,1,2-trichloro-1,1-difluoroethane (CFC-113) and 1-chloro-1,1-difluoroethane (HCFC-142b). Haloacetic acids can be phytotoxic, putatively acting through inhibition of the citric acid cycle. Replicate (n = 3) 12,000-L model aquatic ecosystems (microcosms) were dosed once at 0.5, 1, 5, and 20 mg/L of neutralized CDFA. Three microcosms served as controls. Each microcosm was stocked with eight individual apical shoots of both Myriophyllum spicatum and Myriophyllum sibiricum and sampled at regular intervals over a 42-d exposure period. The plants were assessed for the somatic endpoints of plant length, root growth, node number, and wet and dry mass and the biochemical endpoints of chlorophyll-a/b and carotenoid content as well as citric acid levels. The duckweed Lemna gibba was also introduced into these systems and monitored over a period of 14 d for wet/dry mass, plant/frond number, chlorophyll content, and growth rate. Concentrations of CDFA remained constant in the water column over the course of the fate investigation (241 d), indicating that this compound undergoes little, if any, degradation in aquatic systems. Results showed few statistically significant differences from controls for all three plant species with exposure to CDFA but no biologically relevant impacts. Overall, CDFA does not appear to pose any risk to these aquatic macrophytes at current environmental concentrations.

LOSS OF ORGANIC CHEMICALS IN SOIL: PURE COMPOUND TREATABILITY STUDIES

EPA Science Inventory

Comprehensive screening data on the treatability of 32 organic chemicals in soil were developed. Of the evaluated chemicals, 22 were phenolic compounds. Aerobic batch laboratory microcosm experiments were conducted using two soils: an acidic clay soil with <1% organic matter and ...

Field and laboratory evidence for intrinsic biodegradation of vinyl chloride contamination in a Fe(III)-reducing aquifer

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.; Wilson, J.T.

1998-01-01

Intrinsic bioremediation of chlorinated ethenes in anaerobic aquifers previously has not been considered feasible, due, in large part, to 1) the production of vinyl chloride during microbial reductive dechlorination of higher chlorinated contaminants and 2) the apparent poor biodegradability of vinyl chloride under anaerobic conditions. In this study, a combination of field geochemical analyses and laboratory radiotracer ([1,2-14C] vinyl chloride) experiments was utilized to assess the potential for intrinsic biodegradation of vinyl chloride contamination in an Fe(III)-reducing, anaerobic aquifer. Microcosm experiments conducted under Fe(III)-reducing conditions with material from the Fe(III)-reducing, chlorinated-ethene contaminated aquifer demonstrated significant oxidation of [1,2-14C] vinyl chloride to 14CO2 with no detectable production of ethene or other reductive dehalogenation products. Rates of degradation derived from the microcosm experiments (0.9-1.3% d-1) were consistent with field-estimated rates (0.03-0.2% d-1) of apparent vinyl chloride degradation. Field estimates of apparent vinyl chloride biodegradation were calculated using two distinct approaches; 1) a solute dispersion model and 2) a mass balance assessment. These findings demonstrate that degradation under Fe(III) reducing conditions can be an environmentally significant mechanism for intrinsic bioremediation of vinyl chloride in anaerobic ground-water systems.

A soil microcosm to test the effects of pollutants on soil nematode and microarthropod communities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parmelee, R.W.; Wentsel, R.S.; Checkai, R.T.

1995-12-31

Previous studies have demonstrated that microcosms with field collected soil nematode and microarthropod communities are suitable model systems to detect effects of toxins on soil food web structure and function. The authors investigated the toxicity of copper, cadmium, malathion, and Aroclor 1254 to nematodes (total, bacterivores, fungivores, herbivores, omnivore-predators, hatchlings) and microarthropods (Prostigmata, Mesostigmata, Oribatida, Collembola, other arthropods). Nematodes were sensitive indicators of copper application, and total numbers were reduced at 100 {micro}g g{sup {minus}1}. Fungivore, bacterivore and omnivore-predators were the most susceptible trophic groups. Cadmium had no effects on either nematode or microarthropod communities. Microarthropods were more sensitive tomore » malathion than nematodes, and total microarthropod abundance was lower than controls at 320 {micro}g g{sup {minus}1}. Prostigmatid mites and other arthropods were the most affected groups. Only the herbivore nematode trophic group was affected by malathion, and numbers did not decline until 1,280 {micro}g g{sup {minus}1}. Aroclor 1254 also had a greater negative impact on microarthropods than on nematodes. Total microarthropod abundance declined at 2,500 {micro}g g{sup {minus}1}, while there was no effect on nematodes. Prostigmatid and oribatid mites were the most susceptible groups to PCB application. Strong differential sensitivity between nematode and microarthropod communities indicates that both groups need to be examined to fully evaluate the impact of chemicals on soil systems. The authors conclude that microcosms with field-collected communities of soil microfauna offer high resolution of the ecotoxicological effects of chemicals in complex soil systems.« less

A field method using microcosms to evaluate transfer of Cd, Cu, Ni, Pb and Zn from sewage sludge amended forest soils to Helix aspersa snails.

PubMed

Scheifler, R; Ben Brahim, M; Gomot-de Vaufleury, A; Carnus, J-M; Badot, P-M

2003-01-01

Juvenile Helix aspersa snails exposed in field microcosms were used to assess the transfer of Cd, Cu, Ni, Pb and Zn from forest soils amended with liquid and composted sewage sludge. Zn concentrations and contents were significantly higher in snails exposed to liquid and composted sludge after 5 and 7 weeks of exposure, when compared with control. Trends were less clear for the other metals. Present results show that Zn, among the cocktail of metallic trace elements (MTE) coming from sewage sludge disposal, represents the principal concern for food chain transfer and secondary poisoning risks. The microcosm design used in this experiment was well suited for relatively long-term (about 2 months) active biomonitoring with H. aspersa snails. The snails quickly indicated the variations of MTE concentrations in their immediate environment. Therefore, the present study provides a simple but efficient field tool to evaluate MTE bioavailability and transfer.

Evaluation of the biodegradation of Alaska North Slope oil in microcosms using the biodegradation model BIOB

PubMed Central

Torlapati, Jagadish; Boufadel, Michel C.

2014-01-01

We present the details of a numerical model, BIOB that is capable of simulating the biodegradation of oil entrapped in the sediment. The model uses Monod kinetics to simulate the growth of bacteria in the presence of nutrients and the subsequent consumption of hydrocarbons. The model was used to simulate experimental results of Exxon Valdez oil biodegradation in laboratory columns (Venosa et al., 2010). In that study, samples were collected from three different islands: Eleanor Island (EL107), Knight Island (KN114A), and Smith Island (SM006B), and placed in laboratory microcosms for a duration of 168 days to investigate oil bioremediation through natural attenuation and nutrient amendment. The kinetic parameters of the BIOB model were estimated by fitting to the experimental data using a parameter estimation tool based on Genetic Algorithms (GA). The parameter values of EL107 and KN114A were similar whereas those of SM006B were different from the two other sites; in particular biomass growth at SM006B was four times slower than at the other two islands. Grain size analysis from each site revealed that the specific surface area per unit mass of sediment was considerably lower at SM006B, which suggest that the surface area of sediments is a key control parameter for microbial growth in sediments. Comparison of the BIOB results with exponential decay curves fitted to the data indicated that BIOB provided better fit for KN114A and SM006B in nutrient amended treatments, and for EL107 and KN114A in natural attenuation. In particular, BIOB was able to capture the initial slow biodegradation due to the lag phase in microbial growth. Sensitivity analyses revealed that oil biodegradation at all three locations were sensitive to nutrient concentration whereas SM006B was sensitive to initial biomass concentration due to its slow growth rate. Analyses were also performed to compare the half-lives of individual compounds with that of the overall polycyclic aromatic hydrocarbons

Effects of the pyrethroid insecticide gamma-cyhalothrin on aquatic invertebrates in laboratory and outdoor microcosm tests.

PubMed

van Wijngaarden, René P A; Barber, Ian; Brock, Theo C M

2009-02-01

The sensitivity of a range of freshwater lentic invertebrates to gamma-cyhalothrin (GCH), a single enantiomer of the synthetic pyrethroid lambda-cyhalothrin, was assessed in single species laboratory tests and an outdoor multi-species ecosystem test. The most sensitive species in the laboratory single species tests with GCH was Chaoborus obscuripes (96 h EC(50): 3.8 ng/l). The species sensitivity distribution curve, based on the laboratory 96 h EC(50) acute toxicity data for eight species, gave a median HC(5) value for GCH of 2.12 ng/l. The NOEC(community) derived from the multi-species ecosystem test was 5 ng/l, and the insects Chaoborus sp. and Caenis sp. were identified as the most sensitive species. The results indicate that the median HC(5), based on eight species selected to include those known to be sensitive to pyrethroids, provided a good estimation of the NOEC(community) for GCH. Furthermore, the results for GCH indicated that the endpoints typically used in higher-tier risk assessments for pesticides in Europe (HC(5) and NOEC(community)) were consistent with expectations when compared to the equivalent endpoints for the racemate LCH.

Anaerobic degradation of 1,1,2,2-tetrachloroethane and association with microbial communities in a freshwater tidal wetland, Aberdeen Proving Ground, Maryland : laboratory experiments and comparisons to field data

USGS Publications Warehouse

Lorah, Michelle M.; Voytek, Mary A.; Kirshtein, Julie D.; Jones, Elizabeth J.

2003-01-01

Defining biodegradation rates and processes is a critical part of assessing the feasibility of monitored natural attenuation as a remediation method for ground water containing organic contaminants. During 1998?2001, the U.S. Geological Survey conducted a microbial study at a freshwater tidal wetland along the West Branch Canal Creek, Aberdeen Proving Ground, Maryland, as part of an investigation of natural attenuation of chlorinated volatile organic compounds (VOCs) in the wetland sediments. Geochemical analyses and molecular biology techniques were used to investigate factors controlling anaerobic degradation of 1,1,2,2-tetrachloroethane (TeCA), and to characterize the microbial communities that potentially are important in its degradation. Rapid TeCA and daughter product degradation observed in laboratory experiments and estimated with field data confirm that natural attenuation is a feasible remediation method at this site. The diverse microbial community that seems to be involved in TeCA degradation in the wetland sediments varies with changing spatial and seasonal conditions, allowing continued effective natural attenuation throughout the year. Rates of TeCA degradation in anaerobic microcosm experiments conducted with wetland sediment collected from two different sites (WB23 and WB30) and during three different seasons (March?April 1999, July?August 1999, and October?November 2000) showed little spatial variability but high seasonal variability. Initial first-order degradation rate constants for TeCA ranged from 0.10?0.01 to 0.16?0.05 per day (half-lives of 4.3 to 6.9 days) for March?April 1999 and October?November 2000 microcosms incubated at 19 degrees Celsius, whereas lower rate constants of 0 ? 0.03 and 0.06 ? 0.03 per day were obtained in July?August 1999 microcosms incubated at 19 degrees Celsius. Microbial community profiles showed that low microbial biomass and microbial diversity in the summer, possibly due to competition for nutrients by the

Behavior of pollutant-degrading microorganisms in aquifers: Predictions for genetically engineered organisms

USGS Publications Warehouse

Krumme, M.L.; Smith, R.L.; Egestorff, J.; Thiem, S.M.; Tiedje, J.M.; Timmis, K.N.; Dwyer, D.F.

1994-01-01

Bioremediation via environmental introductions of degradative microorganisms requires that the microbes survive in substantial numbers and effect an increase in the rate and extent of pollutant removal. Combined field and microcosm studies were used to assess these abilities for laboratory-grown bacteria. Following introduction into a contaminated aquifer, viable cells of Pseudomonas sp. B13 were present in the contaminant plume for 447 days; die-off was rapid in pristine areas. In aquifer microcosms, survival of B13 and FR120, a genetically engineered derivative of B13 having enhanced catabolic capabilities for substituted aromatics, was comparable to B13 field results; both bacteria degraded target pollutants in microcosms made with aquifer samples from the aerobic zone of the pollutant plume. Results suggest that field studies with nonrecombinant microorganisms may be coupled to laboratory studies with derivative strains to estimate their bioremediative efficacy. Furthermore, laboratory strains of bacteria can survive for extended periods of time in nature and thus may have important bioremediative applications. ?? 1994 American Chemical Society.

Visual Representations of Microcosm in Textbooks of Chemistry: Constructing a Systemic Network for Their Main Conceptual Framework

ERIC Educational Resources Information Center

Papageorgiou, George; Amariotakis, Vasilios; Spiliotopoulou, Vasiliki

2017-01-01

The main objective of this work is to analyse the visual representations (VRs) of the microcosm depicted in nine Greek secondary chemistry school textbooks of the last three decades in order to construct a systemic network for their main conceptual framework and to evaluate the contribution of each one of the resulting categories to the network.…

[Explore microcosmic connection between autophagy mechanism and follicular development based on "kidney governing reproduction" theory].

PubMed

Bai, Jun; Wu, Ke-Ming; Gao, Ran-Ran

2018-03-01

In the theory of traditional Chinese medicine(TCM) that "kidney storing essence and governing reproduction", reproductive essence is an important part of the kidney essence and acts as the original material of offspring embryos. Sperm, oocyte and zygote should be all included in the range of reproductive essence. Ovum is the essence of reproduction from inborn. The follicles maturation depends on the quality of oocyte and the vigor of kidney essence. Meanwhile, discharge of mature ovum relies on the stimulation and promotion by kidney Qi. Autophagy almost exists in different cells stages and all various of mammalian cells. Many studies have found that autophagy not only participates in the formation of follicles, but also in every phase of the follicles development, and is involved in the occurrence and development of ovarian diseases. Recently, more and more scholars believe that autophagy is a new field to explore the microcosmic relationship between autophagy and TCM. Kidney-nourishing TCM could promote follicular growth and improve variety clinical symptoms by inhibiting the apoptosis of ovarian granulosa cells and reducing follicular atresia. Meanwhile, apoptosis of ovarian granulosa cells is closely related to autophagy of ovarian granulosa cells. In order to provide some theoretical foundation for kidney-nourishing therapy's promoting effect on follicular growth and improving effect on ovarian function, also to further explore the molecular mechanism of kidney-nourishing medicine in promoting follicular development, this paper would explain the microcosmic relationship between autophagy and follicular development based on the theory of "kidney governing reproduction". All of these would be of great significance to prevent and intervene the diseases of reproductive system timely and effectively. Copyright© by the Chinese Pharmaceutical Association.

Degradation of 1,1,2,2-tetrachloroethane in a freshwater tidal wetland: Field and laboratory evidence

USGS Publications Warehouse

Lorah, M.M.; Olsen, L.D.

1999-01-01

Degradation reactions controlling the fate of 1,1,2,2-tetrachloroethane (PCA) in a freshwater tidal wetland that is a discharge area for a contaminated aquifer were investigated by a combined field and laboratory study. Samples from nested piezometers and porous-membrane sampling devices (peepers) showed that PCA concentrations decreased and that less chlorinated daughter products formed as the groundwater became increasingly reducing along upward flow paths through the wetland sediments. The cis and trans isomers of 1,2-dichloroethylene (12DCE) and vinyl chloride (VC) were the predominant daughter products detected from degradation of PCA in the field and in microcosms constructed under methanogenic conditions. Significantly lower ratios of cis-12DCE to trans-12DCE were produced by PCA degradation than by degradation of trichloroethylene, a common co-contaminant with PCA. 1,1,2-Trichloroethane (112TCA) and 1,2-dichloroethane (12DCA) occurred simultaneously with 12DCE, indicating simultaneous hydrogenolysis and dichloroelimination of PCA. From an initial PCA concentration of about 1.5 ??mol/L, concentrations of PCA and its daughter products decreased to below detection within a 1.0-m vertical distance in the wetland sediments and within 34 days in the microcosms. The results indicate that natural attenuation of PCA through complete anaerobic biodegradation can occur in wetlands before sensitive surface water receptors are reached.

Arbuscular-mycorrhizal networks inhibit Eucalyptus tetrodonta seedlings in rain forest soil microcosms.

PubMed

Janos, David P; Scott, John; Aristizábal, Catalina; Bowman, David M J S

2013-01-01

Eucalyptus tetrodonta, a co-dominant tree species of tropical, northern Australian savannas, does not invade adjacent monsoon rain forest unless the forest is burnt intensely. Such facilitation by fire of seedling establishment is known as the "ashbed effect." Because the ashbed effect might involve disruption of common mycorrhizal networks, we hypothesized that in the absence of fire, intact rain forest arbuscular mycorrhizal (AM) networks inhibit E. tetrodonta seedlings. Although arbuscular mycorrhizas predominate in the rain forest, common tree species of the northern Australian savannas (including adult E. tetrodonta) host ectomycorrhizas. To test our hypothesis, we grew E. tetrodonta and Ceiba pentandra (an AM-responsive species used to confirm treatments) separately in microcosms of ambient or methyl-bromide fumigated rain forest soil with or without severing potential mycorrhizal fungus connections to an AM nurse plant, Litsea glutinosa. As expected, C. pentandra formed mycorrhizas in all treatments but had the most root colonization and grew fastest in ambient soil. E. tetrodonta seedlings also formed AM in all treatments, but severing hyphae in fumigated soil produced the least colonization and the best growth. Three of ten E. tetrodonta seedlings in ambient soil with intact network hyphae died. Because foliar chlorosis was symptomatic of iron deficiency, after 130 days we began to fertilize half the E. tetrodonta seedlings in ambient soil with an iron solution. Iron fertilization completely remedied chlorosis and stimulated leaf growth. Our microcosm results suggest that in intact rain forest, common AM networks mediate belowground competition and AM fungi may exacerbate iron deficiency, thereby enhancing resistance to E. tetrodonta invasion. Common AM networks-previously unrecognized as contributors to the ashbed effect-probably help to maintain the rain forest-savanna boundary.

Survival, Biofilm Formation, and Growth Potential of Environmental and Enteric Escherichia coli Strains in Drinking Water Microcosms

PubMed Central

Abberton, Cathy L.; Bereschenko, Ludmila; van der Wielen, Paul W. J. J.

2016-01-01

ABSTRACT Escherichia coli is the most commonly used indicator for fecal contamination in drinking water distribution systems (WDS). The assumption is that E. coli bacteria are of enteric origin and cannot persist for long outside their host and therefore act as indicators of recent contamination events. This study investigates the fate of E. coli in drinking water, specifically addressing survival, biofilm formation under shear stress, and regrowth in a series of laboratory-controlled experiments. We show the extended persistence of three E. coli strains (two enteric isolates and one soil isolate) in sterile and nonsterile drinking water microcosms at 8 and 17°C, with T90 (time taken for a reduction in cell number of 1 log10 unit) values ranging from 17.4 ± 1.8 to 149 ± 67.7 days, using standard plate counts and a series of (reverse transcription-)quantitative PCR [(RT-)Q-PCR] assays targeting 16S rRNA, tuf, uidA, and rodA genes and transcripts. Furthermore, each strain was capable of attaching to a surface and replicating to form biofilm in the presence of nutrients under a range of shear stress values (0.6, 2.0, and 4.4 dynes [dyn] cm−2; BioFlux system; Fluxion); however, cell numbers did not increase when drinking water flowed over the biofilm (P > 0.05 by t test). Finally, E. coli regrowth within drinking water microcosms containing polyethylene PE-100 pipe wall material was not observed in the biofilm or water phase using a combination of culturing and Q-PCR methods for E. coli. The results of this work highlight that when E. coli enters drinking water it has the potential to survive and attach to surfaces but that regrowth within drinking water or biofilm is unlikely. IMPORTANCE The provision of clean, safe drinking water is fundamental to society. WDS deliver water to consumers via a vast network of pipes. E. coli is used as an indicator organism for recent contamination events based on the premise that it cannot survive for long outside its host. A key

Survival, Biofilm Formation, and Growth Potential of Environmental and Enteric Escherichia coli Strains in Drinking Water Microcosms.

PubMed

Abberton, Cathy L; Bereschenko, Ludmila; van der Wielen, Paul W J J; Smith, Cindy J

2016-09-01

Escherichia coli is the most commonly used indicator for fecal contamination in drinking water distribution systems (WDS). The assumption is that E. coli bacteria are of enteric origin and cannot persist for long outside their host and therefore act as indicators of recent contamination events. This study investigates the fate of E. coli in drinking water, specifically addressing survival, biofilm formation under shear stress, and regrowth in a series of laboratory-controlled experiments. We show the extended persistence of three E. coli strains (two enteric isolates and one soil isolate) in sterile and nonsterile drinking water microcosms at 8 and 17°C, with T90 (time taken for a reduction in cell number of 1 log10 unit) values ranging from 17.4 ± 1.8 to 149 ± 67.7 days, using standard plate counts and a series of (reverse transcription-)quantitative PCR [(RT-)Q-PCR] assays targeting 16S rRNA, tuf, uidA, and rodA genes and transcripts. Furthermore, each strain was capable of attaching to a surface and replicating to form biofilm in the presence of nutrients under a range of shear stress values (0.6, 2.0, and 4.4 dynes [dyn] cm(-2); BioFlux system; Fluxion); however, cell numbers did not increase when drinking water flowed over the biofilm (P > 0.05 by t test). Finally, E. coli regrowth within drinking water microcosms containing polyethylene PE-100 pipe wall material was not observed in the biofilm or water phase using a combination of culturing and Q-PCR methods for E. coli The results of this work highlight that when E. coli enters drinking water it has the potential to survive and attach to surfaces but that regrowth within drinking water or biofilm is unlikely. The provision of clean, safe drinking water is fundamental to society. WDS deliver water to consumers via a vast network of pipes. E. coli is used as an indicator organism for recent contamination events based on the premise that it cannot survive for long outside its host. A key public health

Laboratory Governance: Issues for the Study Group on Regional Laboratories.

ERIC Educational Resources Information Center

Schultz, Thomas; Dominic, Joseph

Background information and an analysis of issues involved in the governance of new regional educational laboratories are presented. The new laboratories are to be established through a 1984 competition administered by the National Institute of Education (NIE). The analysis is designed to assist the Study Group on Regional Laboratories to advise…

Biotransformation of BTEX under anaerobic, denitrifying conditions: Field and laboratory observations

NASA Astrophysics Data System (ADS)

Barbaro, J. R.; Barker, J. F.; Lemon, L. A.; Mayfield, C. I.

1992-11-01

Three natural-gradient injection experiments in the Borden aquifer (Ontario, Canada) (˜ 100-300 days in duration) and a 452-day laboratory microcosm experiment were performed to evaluate the biotransformation of BTEX (benzene, toluene, ethylbenzene and o-, m-, p-xylenes) derived from gasoline under anaerobic, denitrifying conditions. Both NO 3-- amended and unamended control (i.e. no NO 3- added) experiments were performed. In the unamended control injection experiment, toluene biotransformed between 1 and 5 m from the injection well. All other aromatic compounds were recalcitrant in this field experiment and all aromatic compounds were recalcitrant in unamended control microcosms. After an acclimatization period, toluene biotransformed relatively rapidly in the presence of NO 3- in both the laboratory and field to a residual level of ˜ 100 μg L -1. In the presence of NO 3- the xylene isomers and ethylbenzene biotransformed to a lesser degree. Benzene was recalcitrant in all experiments. The acetylene blockage technique was used to demonstrate that denitrifying bacteria were active in the presence of NO 3-. In the NO 3--amended injection experiments, little BTEX mass loss occurred beyond the 1-m multilevel-piezometer fence. However, NO 3- continued to decline downgradient, suggesting that other sources of carbon were being utilized by denitrifying bacteria in preference to residual BTEX. In addition to observations on mass loss, these experiments provided evidence of inhibition of BTEX biotransformation in the presence of acetylene, and competitive utilization between toluene, ethylbenzene and the xylene isomers. Given the recalcitrance of benzene and high thresholds of the compounds that did biotransform, the addition of NO 3- as an alternate electron acceptor would not be successful in this aquifer as a remedial measure.

Effects of diquat and fomesafen applied alone and in combination with a nonylphenol polyethoxylate adjuvant on Lemna minor in aquatic indoor microcosms.

PubMed

Gorzerino, Caroline; Quemeneur, Alphonse; Hillenweck, Anne; Baradat, Maryse; Delous, Georges; Ollitrault, Martine; Azam, Didier; Caquet, Thierry; Lagadic, Laurent

2009-03-01

The influence of tank-mix adjuvants on pesticide toxicity remains largely unknown. Agral 90, a nonylphenol polyethoxylated tank-mix adjuvant, has been used with diquat (bipyridylium herbicide) and fomesafen (diphenyl-ether herbicide) in aquatic indoor microcosms in order to compare the toxicity of the single compounds and of binary herbicide-adjuvant mixtures to Lemna minor. Twenty-four microcosms were used and treatments were performed with substances alone or with herbicide-adjuvant binary mixtures, at two concentrations levels (44.4 and 222.2 microg/L for the herbicides, and 100 and 500 microg/L for Agral 90). Toxicity was assessed weekly for 1 month through growth measurements, as inferred from the relative frond number (RFN) and relative frond area (RFA). Concentrations of diquat and fomesafen in water and sediments were measured weekly. The herbicides showed very different behaviour in microcosms, with a rapid disappearance of diquat from the aqueous phase whereas fomesafen levels remained almost constant over time. Diquat strongly inhibited the growth of L. minor whereas fomesafen had no effect on plant growth. Presence of the adjuvant only slightly reduced the effect of the lowest concentration of diquat, probably as a result of dispersion of the herbicide at the water surface. It is concluded that tank-mix adjuvant designed to improve herbicide efficiency in the terrestrial environment did not have any effect on aquatic plants when applied to the aquatic environment.

Effect of organic loading on nitrification and denitrification in a marine sediment microcosm

USGS Publications Warehouse

Caffrey, J.M.; Sloth, N.P.; Kaspar, H.F.; Blackburn, T.H.

1993-01-01

The effects of organic additions on nitrification and denitrification were examined in sediment microcosms. The organic material, heat killed yeast, had a C/N ratio of 7.5 and was added to sieved, homogenized sediments. Four treatments were compared: no addition (control, 30 g dry weight (dw) m-2 mixed throughout the 10 cm sediment column (30 M), 100 g dw m-2 mixed throughout sediments (100M), and 100 g dw m-2 mixed into top 1 cm (100S). After the microcosms had been established for 7-11 days, depth of O2 penetration, sediment-water fluxes and nitrification rates were measured. Nitrification rates were measured using three different techniques: N-serve and acetylene inhibition in intact cores, and nitrification potentials in slurries. Increased organic additions decreased O2 penetration from 2.7 to 0.2 mm while increasing both O2 consumption, from 30 to 70 mmol O2 m-2 d-1, and NO3- flux into sediments. Nitrification rates in intact cores were similar for the two methods. Highest rates occurred in the 30 M treatment, while the lowest rate was measured in the 100S treatment. Total denitrification rates (estimated from nitrification and nitrate fluxes) increased with increased organic addition, because of the high concentrations of NO3- (40 ??M) in the overlying water. The ratio of nitrification: denitrification was used as an indication of the importance of nitrification as the NO3- supply for denitrification. This ratio decreased from 1.55 to 0.05 with increased organic addition.

Use of Acetate, Propionate, and Butyrate for Reduction of Nitrate and Sulfate and Methanogenesis in Microcosms and Bioreactors Simulating an Oil Reservoir.

PubMed

Chen, Chuan; Shen, Yin; An, Dongshan; Voordouw, Gerrit

2017-04-01

Acetate, propionate, and butyrate (volatile fatty acids [VFA]) occur in oil field waters and are frequently used for microbial growth of oil field consortia. We determined the kinetics of use of these VFA components (3 mM each) by an anaerobic oil field consortium in microcosms containing 2 mM sulfate and 0, 4, 6, 8, or 13 mM nitrate. Nitrate was reduced first, with a preference for acetate and propionate. Sulfate reduction then proceeded with propionate (but not butyrate) as the electron donor, whereas the fermentation of butyrate (but not propionate) was associated with methanogenesis. Microbial community analyses indicated that Paracoccus and Thauera ( Paracoccus - Thauera ), Desulfobulbus , and Syntrophomonas - Methanobacterium were the dominant taxa whose members catalyzed these three processes. Most-probable-number assays showed the presence of up to 10 7 /ml of propionate-oxidizing sulfate-reducing bacteria (SRB) in waters from the Medicine Hat Glauconitic C field. Bioreactors with the same concentrations of sulfate and VFA responded similarly to increasing concentrations of injected nitrate as observed in the microcosms: sulfide formation was prevented by adding approximately 80% of the nitrate dose needed to completely oxidize VFA to CO 2 in both. Thus, this work has demonstrated that simple time-dependent observations of the use of acetate, propionate, and butyrate for nitrate reduction, sulfate reduction, and methanogenesis in microcosms are a good proxy for these processes in bioreactors, monitoring of which is more complex. IMPORTANCE Oil field volatile fatty acids acetate, propionate, and butyrate were specifically used for nitrate reduction, sulfate reduction, and methanogenic fermentation. Time-dependent analyses of microcosms served as a good proxy for these processes in a bioreactor, mimicking a sulfide-producing (souring) oil reservoir: 80% of the nitrate dose required to oxidize volatile fatty acids to CO 2 was needed to prevent souring in both

Use of Acetate, Propionate, and Butyrate for Reduction of Nitrate and Sulfate and Methanogenesis in Microcosms and Bioreactors Simulating an Oil Reservoir

PubMed Central

Shen, Yin; An, Dongshan; Voordouw, Gerrit

2017-01-01

ABSTRACT Acetate, propionate, and butyrate (volatile fatty acids [VFA]) occur in oil field waters and are frequently used for microbial growth of oil field consortia. We determined the kinetics of use of these VFA components (3 mM each) by an anaerobic oil field consortium in microcosms containing 2 mM sulfate and 0, 4, 6, 8, or 13 mM nitrate. Nitrate was reduced first, with a preference for acetate and propionate. Sulfate reduction then proceeded with propionate (but not butyrate) as the electron donor, whereas the fermentation of butyrate (but not propionate) was associated with methanogenesis. Microbial community analyses indicated that Paracoccus and Thauera (Paracoccus-Thauera), Desulfobulbus, and Syntrophomonas-Methanobacterium were the dominant taxa whose members catalyzed these three processes. Most-probable-number assays showed the presence of up to 107/ml of propionate-oxidizing sulfate-reducing bacteria (SRB) in waters from the Medicine Hat Glauconitic C field. Bioreactors with the same concentrations of sulfate and VFA responded similarly to increasing concentrations of injected nitrate as observed in the microcosms: sulfide formation was prevented by adding approximately 80% of the nitrate dose needed to completely oxidize VFA to CO2 in both. Thus, this work has demonstrated that simple time-dependent observations of the use of acetate, propionate, and butyrate for nitrate reduction, sulfate reduction, and methanogenesis in microcosms are a good proxy for these processes in bioreactors, monitoring of which is more complex. IMPORTANCE Oil field volatile fatty acids acetate, propionate, and butyrate were specifically used for nitrate reduction, sulfate reduction, and methanogenic fermentation. Time-dependent analyses of microcosms served as a good proxy for these processes in a bioreactor, mimicking a sulfide-producing (souring) oil reservoir: 80% of the nitrate dose required to oxidize volatile fatty acids to CO2 was needed to prevent souring in both

A strategy for aromatic hydrocarbon bioremediation under anaerobic conditions and the impacts of ethanol: A microcosm study

NASA Astrophysics Data System (ADS)

Chen, Yu Dao; Barker, James F.; Gui, Lai

2008-02-01

Increased use of ethanol-blended gasoline (gasohol) and its potential release into the subsurface have spurred interest in studying the biodegradation of and interactions between ethanol and gasoline components such as benzene, toluene, ethylbenzene and xylene isomers (BTEX) in groundwater plumes. The preferred substrate status and the high biological oxygen demand (BOD) posed by ethanol and its biodegradation products suggests that anaerobic electron acceptors (EAs) will be required to support in situ bioremediation of BTEX. To develop a strategy for aromatic hydrocarbon bioremediation and to understand the impacts of ethanol on BTEX biodegradation under strictly anaerobic conditions, a microcosm experiment was conducted using pristine aquifer sand and groundwater obtained from Canadian Forces Base Borden, Canada. The initial electron accepter pool included nitrate, sulfate and/or ferric iron. The microcosms typically contained 400 g of sediment, 600˜800 ml of groundwater, and with differing EAs added, and were run under anaerobic conditions. Ethanol was added to some at concentrations of 500 and 5000 mg/L. Trends for biodegradation of aromatic hydrocarbons for the Borden aquifer material were first developed in the absence of ethanol, The results showed that indigenous microorganisms could degrade all aromatic hydrocarbons (BTEX and trimethylbenzene isomers-TMB) under nitrate- and ferric iron-combined conditions, but not under sulfate-reducing conditions. Toluene, ethylbenzene and m/p-xylene were biodegraded under denitrifying conditions. However, the persistence of benzene indicated that enhancing denitrification alone was insufficient. Both benzene and o-xylene biodegraded significantly under iron-reducing conditions, but only after denitrification had removed other aromatics. For the trimethylbenzene isomers, 1,3,5-TMB biodegradation was found under denitrifying and then iron-reducing conditions. Biodegradation of 1,2,3-TMB or 1,2,4-TMB was slower under iron

Arbuscular-Mycorrhizal Networks Inhibit Eucalyptus tetrodonta Seedlings in Rain Forest Soil Microcosms

PubMed Central

Janos, David P.; Scott, John; Aristizábal, Catalina; Bowman, David M. J. S.

2013-01-01

Eucalyptus tetrodonta, a co-dominant tree species of tropical, northern Australian savannas, does not invade adjacent monsoon rain forest unless the forest is burnt intensely. Such facilitation by fire of seedling establishment is known as the "ashbed effect." Because the ashbed effect might involve disruption of common mycorrhizal networks, we hypothesized that in the absence of fire, intact rain forest arbuscular mycorrhizal (AM) networks inhibit E. tetrodonta seedlings. Although arbuscular mycorrhizas predominate in the rain forest, common tree species of the northern Australian savannas (including adult E. tetrodonta) host ectomycorrhizas. To test our hypothesis, we grew E. tetrodonta and Ceiba pentandra (an AM-responsive species used to confirm treatments) separately in microcosms of ambient or methyl-bromide fumigated rain forest soil with or without severing potential mycorrhizal fungus connections to an AM nurse plant, Litsea glutinosa. As expected, C. pentandra formed mycorrhizas in all treatments but had the most root colonization and grew fastest in ambient soil. E. tetrodonta seedlings also formed AM in all treatments, but severing hyphae in fumigated soil produced the least colonization and the best growth. Three of ten E. tetrodonta seedlings in ambient soil with intact network hyphae died. Because foliar chlorosis was symptomatic of iron deficiency, after 130 days we began to fertilize half the E. tetrodonta seedlings in ambient soil with an iron solution. Iron fertilization completely remedied chlorosis and stimulated leaf growth. Our microcosm results suggest that in intact rain forest, common AM networks mediate belowground competition and AM fungi may exacerbate iron deficiency, thereby enhancing resistance to E. tetrodonta invasion. Common AM networks–previously unrecognized as contributors to the ashbed effect–probably help to maintain the rain forest–savanna boundary. PMID:23460899

Nitrogen removal in Myriophyllum aquaticum wetland microcosms for swine wastewater treatment: 15 N-labelled nitrogen mass balance analysis.

PubMed

Zhang, Shunan; Liu, Feng; Xiao, Runlin; He, Yang; Wu, Jinshui

2017-01-01

Ecological treatments are effective for treating agricultural wastewater. In this study, wetland microcosms vegetated with Myriophyllum aquaticum were designed for nitrogen (N) removal from two strengths of swine wastewater, and 15 N-labelled ammonium (NH 4 + -N) was added to evaluate the dominant NH 4 + -N removal pathway. The results showed that 98.8% of NH 4 + -N and 88.3% of TN (TN: 248.6 mg L -1 ) were removed from low-strength swine wastewater (SW1) after an incubation of 21 days, with corresponding values for high-strength swine wastewater (SW2) being 99.2% of NH 4 + -N and 87.8% of TN (TN: 494.9 mg L -1 ). Plant uptake and soil adsorption respectively accounted for 24.0% and 15.6% of the added 15 N. Meanwhile, above-ground tissues of M. aquaticum had significantly higher biomass and TN content than below-ground (P < 0.05). 15 N mass balance analysis indicated that gas losses contributed 52.0% to the added 15 N, but the N 2 O flux constituted only 7.5% of total gas losses. The dynamics of NO 3 - -N and N 2 O flux revealed that strong nitrification and denitrification occurred in M. aquaticum microcosms, which was a dominant N removal pathway. These findings demonstrated that M. aquaticum could feasibly be used to construct wetlands for high N-loaded animal wastewater treatment. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Dichloroethene and Vinyl Chloride Degradation Potential in Wetland Sediments at Twin Lakes and Pen Branch, Savannah River National Laboratory, South Carolina

USGS Publications Warehouse

Bradley, Paul M.

2007-01-01

A series of 14C-radiotracer-based microcosm experiments was conducted to assess the mechanisms and products of degradation of dichloroethene (DCE) and vinyl chloride (VC) in wetland sediments at the Department of Energy (DOE) Savannah River National Laboratory. This project investigated the potential for biotic and abiotic DCE and VC degradation in wetland sediments from the Twin Lakes area of the C-BRP investigative unit and from the portion of Pen Branch located directly down gradient from the CMP investigative unit. Substantial degradation of [1,2-14C] DCE and [1,2-14C] VC to 14CO2 was observed in all viable sediment microcosms prepared under oxic conditions. These results indicate that microbial mineralization processes, involving direct oxidation or cometabolic oxidation, are the primary mechanisms of DCE and VC biodegradation in Twin Lake and Pen Branch sediments under oxic conditions. Substantial degradation of [1,2-14C] DCE and [1,2-14C] VC was observed in all viable sediment microcosms incubated under anoxic conditions. Production of 14CO2 was observed in all sediment microcosms under anoxic conditions. In general, the accumulation of mineralization products (14CO2 and 14CH4) was comparable to the accumulation of those reduced daughter products (14C-VC, 14C-ethene or 14C-ethane) traditionally identified with chloroethene reductive dechlorination. These results indicate that microbial mineralization processes can be an important component of DCE and VC degradation in Twin Lake and Pen Branch sediments under anoxic conditions. These results demonstrate that an evaluation of the efficiency of in situ DCE and VC biodegradation in Twin Lakes and Pen Branch that is based solely on the observed accumulation of reduced daughter products may underestimate substantially the total extent of contaminant biodegradation and, thus, the contribution of biodegradation to overall contaminant attenuation. No evidence of abiotic degradation of [1,2-14C] DCE or [1,2-14C] VC

Temporal succession in carbon incorporation from macromolecules by particle-attached bacteria in marine microcosms: Particle-attached bacteria incorporating organic carbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayali, Xavier; Stewart, Benjamin; Mabery, Shalini

Here, we investigated bacterial carbon assimilation from stable isotope-labelled macromolecular substrates (proteins; lipids; and two types of polysaccharides, starch and cellobiose) while attached to killed diatom detrital particles during laboratory microcosms incubated for 17 days. Using Chip-SIP (secondary ion mass spectrometry analysis of RNA microarrays), we identified generalist operational taxonomic units (OTUs) from the Gammaproteobacteria, belonging to the genera Colwellia, Glaciecola, Pseudoalteromonas and Rheinheimera, and from the Bacteroidetes, genera Owenweeksia and Maribacter, that incorporated the four tested substrates throughout the incubation period. Many of these OTUs exhibited the highest isotope incorporation relative to the others, indicating that they were likelymore » the most active. Additional OTUs from the Gammaproteobacteria, Bacteroidetes and Alphaproteobacteria exhibited generally (but not always) lower activity and did not incorporate all tested substrates at all times, showing species succession in organic carbon incorporation. We also found evidence to suggest that both generalist and specialist OTUs changed their relative substrate incorporation over time, presumably in response to changing substrate availability as the particles aged. This pattern was demonstrated by temporal succession from relatively higher starch incorporation early in the incubations, eventually switching to higher cellobiose incorporation after 2 weeks.« less

Fate of metal resistance genes in arable soil after manure application in a microcosm study.

PubMed

Xiong, Wenguang; Zeng, Zhenling; Zhang, Yiming; Ding, Xueyao; Sun, Yongxue

2015-03-01

Manure application contributes to the spread and persistence of metal resistance genes (MRGs) in the environment. We investigated the fate of copper (Cu) and zinc (Zn) resistance genes (pcoA, pcoD and zntA) in arable soil after Cu/Zn-containing manure application. Manure with or without addition of metals (Cu/Zn) was added in a soil microcosm over 2 months. Soil samples were collected for analysis on day 0, 30 and 60. The abundances of all MRGs (pcoA, pcoD and zntA) in manure group were significantly higher than those in untreated soil and manure+metals groups. All MRGs dissipated 1.2-1.3 times faster in manure group (from -90 ± 8% to -93 ± 7%) than those in manure+metals group (from -68 ± 8% to -78 ± 5%). The results indicated that manure from healthy pigs contributed to the occurrence of metals (Cu/Zn) and MRGs (pcoA, pcoD and zntA) in arable soil. The significant effects of manure application on the accumulation of pcoA, pcoD and zntA lasted for 1-2 months. Cu/Zn can slow down the dissipation of pcoA, pcoD and zntA after manure application. This is the first report to investigate the fate of MRGs in soil after manure application. Copyright © 2014 Elsevier Inc. All rights reserved.

Entry of Yersinia Pestis into the Viable but Nonculturable State in a Low-Temperature Tap Water Microcosm

DTIC Science & Technology

2011-03-16

to enter the VBNC state [17,18,19,20]. In addition, many other bacterial pathogens, including Francisella tularensis, Vibrio cholerae, and Escherichia...sterilized distilled water microcosms at 4uC after 21 days [31]. Likewise, Linder and Oliver reported that Vibrio vulnificus entered the VBNC state... Vibrio cholerae, and Escherichia coli enter the VBNC state [12,21]. In addition, the two closest pathogenic relatives of Y. pestis, namely Y

Evaluation of the biodegradability of petroleum in microcosm systems by using mangrove sediments from Camamu Bay, Bahia, Brazil.

PubMed

Santos, A C F; Rezende, R P; Brendel, M; Souza, S S; Gonçalves, A C S; Dias, J C T

2014-03-24

We investigated the biodegradability of oil in mangrove sediment from Camamu Bay and measured its effect on the bacterial community. Microcosms of mangrove sediment were contaminated with 0.1, 0.5, 1, 2, and 5% (w/v) oil, and the microbial activity was compared to that in uncontaminated sediment. The evolution of CO2 and gas chromatography showed the mineralization of oil compounds, which could reach 100%. Bacterial diversity was determined by polymerase chain reaction using a set of primers for the V3 and V6-V8 regions of 16S rDNA. The band profile obtained by denaturing gradient gel electrophoresis of the amplicons that were obtained for the V3 region showed a negative correlation between band number and oil concentration, whereas that of the V6-V8 region showed a positive correlation between band numbers and oil concentration. The latter also gave similar results for microcosms that were contaminated with 2 and 5% oil. These results demonstrate the mangrove sediment's capacity to recover from oil contamination (in vitro) and suggest that native mangrove microorganisms contain enzymes necessary for the catabolism of oil.

Behavior of N-ethyl perfluorooctane sulfonamido acetic acid (N-EtFOSAA) in biosolids amended soil-plant microcosms of seven plant species: Accumulation and degradation.

PubMed

Wen, Bei; Pan, Ying; Shi, Xiaoli; Zhang, Hongna; Hu, Xiaoyu; Huang, Honglin; Lv, Jitao; Zhang, Shuzhen

2018-06-13

Perfluorooctane sulfonate (PFOS) precursors have been found extensively in sewage sludge and biosolids-amended soils. The degradation of these precursors are regarded as a significant source of PFOS in the environment. In this study, the accumulation of N-ethyl perfluorooctane sulfonamido acetic acid (N-EtFOSAA) in the plants of seven species, namely alfalfa, lettuce, maize, mung bean, radish, ryegrass, and soybean from biosolids-amended soil, and the degradation kinetics of N-EtFOSAA in soil-plant microcosms were evaluated over 60 days. N-EtFOSAA was found in the roots of all plant species, while was not in stems and leaves. The root concentration factors of N-EtFOSAA ranged 0.52-1.37 (pmol/g root )/(pmol/g soil ). Stepwise multiple regression analysis was used to elucidate the accumulation of N-EtFOSAA in the roots of plants. The results showed that the root protein and lipid contents explain 85.0% of the variation in root N-EtFOSAA levels (P < 0.05). Four degradation products, including N-ethyl perfluorooctane sulfonamide (N-EtFOSA), perfluorooctane sulfonamide acetate (FOSAA), perfluorooctane sulfonamide (FOSA) and PFOS were found in soils and plant roots, stems and leaves, indicating the degradation of N-EtFOSAA in soil-plant system. Degradation kinetics fitted a first-order kinetic model well. Degradation rate constants of N-EtFOSAA in the microcosms with plants ranged 0.063-0.165 d -1 , which was 1.40-3.6 times higher than those without plants. Degradation rate constant of maize was relatively higher than those of other plant species. The results is the first to reveal N-EtFOSAA accumulation in plants and degradation in soil-plant microcosms. Copyright © 2018. Published by Elsevier B.V.

Inhibitory Effect of Veterinary Antibiotics on Denitrification in Groundwater: A Microcosm Approach

PubMed Central

Kim, Kangjoo; Cho, Ju-Sik; Lee, Young Han; Joo, Young Kyoo; Lee, Sang Soo

2014-01-01

Veterinary antibiotics in groundwater may affect natural microbial denitrification process. A microcosm study was conducted to evaluate the influence of sulfamethazine and chlortetracycline at different concentrations (0, 0.01, 0.1, and 1.0 mg/L) on nitrate reduction in groundwater under denitrifying condition. Decrease in nitrate removal and nitrite production was observed with the antibiotics. Maximum inhibition of nitrate removal was observed after seven days of incubation with 0.01 mg/L sulfamethazine (17.0%) and 1.0 mg/L chlortetracycline (15.4%). The nitrite production was inhibited with 1.0 mg/L sulfamethazine to 82.0% and chlortetracycline to 31.1%. The initial/final nitrate concentrations indicated that 0.01 mg/L sulfamethazine and 1.0 mg/L chlortetracycline were most effective in inhibiting activity of denitrifying bacteria in groundwater. After 12 days of incubation, the sulfamethazine biodegradation was observed whereas chlortetracycline was persistent. Sulfamethazine and chlortetracycline in groundwater could inhibit the growth and capability of naturally occurring denitrifying bacteria, thereby threatening nitrate pollution in groundwater. PMID:24757442

Migration of Chemotactic Bacteria Transverse to Flow in Response to a Benzoate Source Plume Created in a Saturated Sand-Packed Microcosm

NASA Astrophysics Data System (ADS)

Ford, R.; Boser, B.

2012-12-01

Bioremediation processes depend on contact between microbial populations and the groundwater contaminants that they biodegrade. Chemotaxis, the ability of bacteria to sense a chemical gradient and swim preferentially toward locations of higher concentration, can enhance the transport of bacteria toward contaminant sources that may not be readily accessible by advection and dispersion alone. A two-dimensional rectangular-shaped microcosm packed with quartz sand was used to quantify the effect of chemotaxis on the migration of bacteria within a saturated model aquifer system. Artificial groundwater was pumped through the microcosm at a rate of approximately 1 m/day. A plume of sodium benzoate was created by continuous injection into an upper port of the microcosm to generate a chemical gradient in the vertical direction transverse to flow. Chemotactic bacteria, Pseudomonas putida F1, or the nonchemotactic mutant, P. putida F1 CheA, were injected with a conservative tracer in a port several centimeters below the benzoate position. As the injectates traversed the one-meter length of the microcosm, samples were collected from a dozen effluent ports to determine vertical concentration distributions for the bacteria, benzoate and tracer. A moment analysis was implemented to estimate the center of mass, variance, and skewness of the concentration profiles. The transverse dispersion coefficient and the transverse dispersivity for chemotactic and nonchemotactic bacteria were also evaluated. Experiments performed with a continuous injection of bacteria showed that the center of mass for chemotactic bacteria was closer to the benzoate source on average than the nonchemotactic control (relative to the conservative tracer). These results demonstrated that chemotaxis can increase bacterial transport toward contaminants, potentially enhancing the effectiveness of in situ bioremediation. Experiments with 2 cm and 3 cm spacing between bacteria and benzoate injection locations were

Survival, growth, and body residues of Hyalella azteca (Saussure) exposed to fipronil contaminated sediments from non-vegetated and vegetated microcosms

USDA-ARS?s Scientific Manuscript database

We assessed chronic effects of fipronil and metabolite contaminated sediments from non-vegetated and Thallia dealbata vegetated wetland microcosms on Hyalella azteca during wet and dry exposures. Mean sediment concentrations (ng g-1) ranged from 0.72-1.26, 0.01-0.69, 0.07-0.23, and 0.49-7.87 for fip...

Data quality scoring system for microcosm and mesocosm studies used to derive a level of concern for atrazine.

PubMed

Giddings, Jeffrey M; Campana, David; Nair, Shyam; Brain, Richard

2018-04-16

The US Environmental Protection Agency (USEPA) has historically used different methods to derive an aquatic level of concern (LoC) for atrazine, though all have generally relied on an expanding set of mesocosm and microcosm ("cosm") studies for calibration. The database of results from ecological effects studies with atrazine in cosms now includes 108 data points from 39 studies and forms the basis for assessing atrazine's potential to impact aquatic plant communities. Inclusion of the appropriate cosm studies and accurate interpretation of each data point-delineated as binary scores of "effect" (effect score 1) or "no effect" (effect score 0) of a specific atrazine exposure profile on plant communities in a single study-is critical to USEPA's approach to determining the LoC. We reviewed the atrazine cosm studies in detail and carefully interpreted their results in terms of the binary effect scores. The cosm database includes a wide range of experimental systems and study designs, some of which are more relevant to natural plant communities than others. Moreover, the studies vary in the clarity and consistency of their results. We therefore evaluated each study against objective criteria for relevance and reliability to produce a weighting score that can be applied to the effect scores when calculating the LoC. This approach is useful because studies that are more relevant and reliable have greater influence on the LoC than studies with lower weighting scores. When the current iteration of USEPA's LoC approach, referred to as the plant assemblage toxicity index (PATI), was calibrated with the weighted cosm data set, the result was a 60-day LoC of 21.2 μg/L. Integr Environ Assess Manag 2018;00:000-000. © 2018 The Authors. Integrated Environmental Assessment and Management Published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC). © 2018 The Authors. Integrated Environmental Assessment and Management Published by

Local knowledge, environmental politics, and the founding of ecology in the United States. Stephen Forbes and "The Lake as a Microcosm" (1887).

PubMed

Schneider, D W

2000-12-01

Stephen Forbes's "The Lake as a Microcosm" is one of the founding documents of the science of ecology in the United States. By tracing the connections between scientists and local fishermen underlying the research on floodplain lakes presented in "The Lake as a Microcosm," this essay shows how the birth of ecology was tied to local knowledge and the local politics of environmental transformation. Forbes and the other scientists of the Illinois Natural History Survey relied on fishermen for manual labor, expertise in catching fish, and knowledge of the natural history of the fishes. As Forbes and his colleagues worked in close contact with fishermen, they also adopted many of their political concerns over the privatization of the floodplain and became politically active in supporting their interests. The close connection between scientists and local knowledge forced the ecologists to reframe the boundaries of ecology as objective or political, pure or applied, local or scientific.

[Microcosmic mechanisms of amorphous indomethacin crystallization and the influence of nano-coating on crystallization].

PubMed

Hui, Ou-Yang; Yi, Tao; Zheng, Qin; Liu, Feng

2011-06-01

Amorphous drugs have higher solubility, better oral bioavailability and are easier to be absorbed than their crystalline counterparts. However, the amorphous drugs, with weak stability, are so easy to crystallize that they will lose the original advantages. Polarization microscope, scanning electron microscope, differential scanning calorimetry, X-ray diffractomer and Raman spectroscopy were used to study the microcosmic crystallization mechanisms of amorphous indometacin and the performance of the drug crystals. The results showed that the growth rate of amorphous indometacin crystals at the free surface was markedly faster than that through the bulk, and that the crystal growth rate decreased observably after spraying an ultrathin melting gold (10 nm) at the free surface of the drug. These results indicated that the high growth rates of amorphous drugs crystals at the free surface were the key to their stability and that an ultrathin coating could be applied to enhance the stability of amorphous drugs.

Herbicide mitigation in microcosms simulating stormwater basins subject to polluted water inputs.

PubMed

Bois, P; Huguenot, D; Jézéquel, K; Lollier, M; Cornu, J Y; Lebeau, T

2013-03-01

Non-point source pollution as a result of wine-growing activity is of high concern. Stormwater basins (SWB) found downstream of vineyard watersheds could show a potential for the mitigation of runoff water containing herbicides. In this study, mitigation of vinery-used herbicides was studied in microcosms with a very similar functioning to that recorded in SWB. Mitigation efficiency of glyphosate, diuron and 3,4-dichloroaniline (3,4-DCA) was investigated by taking into account hydraulic flow rate, mitigation duration, bioaugmentation and plant addition. Mitigation efficiency measured in water ranged from 63.0% for diuron to 84.2% for 3,4-DCA and to 99.8% for glyphosate. Water-storage duration in the SWB and time between water supplies were shown to be the most influential factors on the mitigation efficiency. Six hours water-storage duration allowed an efficient sorption of herbicides and their degradation by indigenous microorganisms in 5 weeks. Neither bioaugmentation nor plant addition had a significant effect on herbicide mitigation. Our results show that this type of SWB are potentially relevant for the mitigation of these herbicides stemming from wine-growing activity, providing a long enough hydraulic retention time. Copyright © 2012 Elsevier Ltd. All rights reserved.

The fate of isoproturon in a freshwater microcosm with Lemna minor as a model organism.

PubMed

Böttcher, Thomas; Schroll, Reiner

2007-01-01

Degradation, bioaccumulation and volatile loss of the 14C-labeled phenylurea herbicide isoproturon (IPU) was examined in a freshwater microcosm with the free floating macrophyte species Lemna minor during a 21-day exposure time. Isoproturon volatilisation was very low with 0.13+/-0.01% of the initially applied herbicide. Only a minor amount of the herbicide was completely metabolised, presumably by rhizosphere microorganisms and released as 14CO2. In total, about 9% isoproturon was removed from the aquatic medium during 21 days. The major portion of the pesticide was removed by bioaccumulation of Lemna minor (5.0+/-0.8%) and the bioconcentration factor (BCF) based on freshweight was 15.8+/-0.2. However, this study indicated a high persistence of IPU in freshwater ecosystems and a potential hazard due to bioaccumulation in non-target species. The novel experimental system of this study, developed for easy use and multiple sampling abilities, enabled quantitatively studying the fate of isoproturon and showed high reproducibility with a mean average (14)C-recovery rate of 97.1+/-0.7%.

Ecological impacts of time-variable exposure regimes to the fungicide azoxystrobin on freshwater communities in outdoor microcosms.

PubMed

Zafar, Mazhar Iqbal; Belgers, J Dick M; Van Wijngaarden, Rene P A; Matser, Arriënne; Van den Brink, Paul J

2012-05-01

This paper evaluates the effects of different time-varying exposure patterns of the strobilurin fungicide azoxystrobin on freshwater microsocosm communities. These exposure patterns included two treatments with a similar peak but different time-weighted average (TWA) concentrations, and two treatments with similar TWA but different peak concentrations. The experiment was carried out in outdoor microcosms under four different exposure regimes; (1) a continuous application treatment of 10 μg/L (CAT(10)) for 42 days (2), a continuous application treatment of 33 μg/L (CAT(33)) for 42 days (3), a single application treatment of 33 μg/L (SAT(33)) and (4) a four application treatment of 16 μg/L (FAT(16)), with a time interval of 10 days. Mean measured 42-d TWA concentrations in the different treatments were 9.4 μg/L (CAT(10)), 32.8 μg/L (CAT(33)), 14.9 μg/L (SAT(33)) and 14.7 μg/L (FAT(16)). Multivariate analyses demonstrated significant changes in zooplankton community structure in all but the CAT(10) treated microcosms relative to that of controls. The largest adverse effects were reported for zooplankton taxa belonging to Copepoda and Cladocera. By the end of the experimental period (day 42 after treatment), community effects were of similar magnitude for the pulsed treatment regimes, although the magnitude of the initial effect was larger in the SAT(33) treatment. This indicates that for long-term effects the TWA is more important for most zooplankton species in the test system than the peak concentration. Azoxystrobin only slightly affected some species of the macroinvertebrate, phytoplankton and macrophyte assemblages. The overall no observed ecologically adverse effect concentrations (NOEAEC) in this study was 10 µg/L.

Degradation of trichloroethylene by Pseudomonas cepacia G4 and the constitutive mutant strain G4 5223 PR1 in aquifer microcosms

USGS Publications Warehouse

Krumme, M.L.; Timmis, K.N.; Dwyer, D.F.

1993-01-01

Pseudomonas cepacia G4 degrades trichloroethylene (TCE) via a degradation pathway for aromatic compounds which is induced by substrates such as phenol and tryptophan. P. cepacia G4 5223 PR1 (PR1) is a Tn5 insertion mutant which constitutively expresses the toluene ortho-monooxygenase responsible for TCE degradation. In groundwater microcosms, phenol-induced strain G4 and noninduced strain PR1 degraded TCE (20 and 50 microM) to nondetectable levels (< 0.1 microM) within 24 h at densities of 10(8) cells per ml; at lower densities, degradation of TCE was not observed after 48 h. In aquifer sediment microcosms, TCE was reduced from 60 to < 0.1 microM within 24 h at 5 x 10(8) PR1 organisms per g (wet weight) of sediment and from 60 to 26 microM over a period of 10 weeks at 5 x 10(7) PR1 organisms per g. Viable G4 and PR1 cells decreased from approximately 10(7) to 10(4) per g over the 10-week period.

Microcosm investigation on phytoremediation of Cr using Azolla pinnata.

PubMed

Rai, Prabhat Kumar

2010-01-01

The extent of Chromium (Cr) pollution in Singrauli industrial region, India was assessed and phytoremediation capacity of a small water fern, Azolla pinnata R.BR (Azollaceae) was observed to purify waters polluted by Cr under microcosm condition. Azolla pinnata endemic to India is a potential hyper-accumulator of heavy metals. During 13 days of the experiment the fern was grown in the aqueous medium containing Cr3+ and CrO4(2-) ions, each in a concentration 0.5, 1.0, and 3.0 mg L(-1). The presence of these ions caused a + 3.1 to -37.5% inhibition of Azolla pinnata growth in comparison to the control. After 13 days of the experiment, metal contents in the solution was decreased up to 70% (CrO4(2-) 3.0 mg L(-1) treatment) to 88% (CrO4(2-) 0.5 mg L(-1) treatment). In the Azolla pinnata tissues, the concentration of couple of the ionic forms of Cr under investigation ranged from 415 to 1095 mg kg(-1) dry mass (dm); the highest level being found for Cr (III) containing solution.

Laboratory-Scale Evidence for Lightning-Mediated Gene Transfer in Soil

PubMed Central

Demanèche, Sandrine; Bertolla, Franck; Buret, François; Nalin, Renaud; Sailland, Alain; Auriol, Philippe; Vogel, Timothy M.; Simonet, Pascal

2001-01-01

Electrical fields and current can permeabilize bacterial membranes, allowing for the penetration of naked DNA. Given that the environment is subjected to regular thunderstorms and lightning discharges that induce enormous electrical perturbations, the possibility of natural electrotransformation of bacteria was investigated. We demonstrated with soil microcosm experiments that the transformation of added bacteria could be increased locally via lightning-mediated current injection. The incorporation of three genes coding for antibiotic resistance (plasmid pBR328) into the Escherichia coli strain DH10B recipient previously added to soil was observed only after the soil had been subjected to laboratory-scale lightning. Laboratory-scale lightning had an electrical field gradient (700 versus 600 kV m−1) and current density (2.5 versus 12.6 kA m−2) similar to those of full-scale lightning. Controls handled identically except for not being subjected to lightning produced no detectable antibiotic-resistant clones. In addition, simulated storm cloud electrical fields (in the absence of current) did not produce detectable clones (transformation detection limit, 10−9). Natural electrotransformation might be a mechanism involved in bacterial evolution. PMID:11472916

Production and processing of a 59-kilodalton exochitinase during growth of Streptomyces lividans carrying pCHIO12 in soil microcosms amended with crab or fungal chitin.

PubMed Central

Vionis, A P; Niemeyer, F; Karagouni, A D; Schrempf, H

1996-01-01

Streptomyces lividans (pCHIO12), which carries the previously cloned Streptomyces olivaceoviridis exo-chiO1 gene on a multicopy vector, secretes a 59-kDa exochitinase, consisting of a catalytic domain (40 kDa), a central fibronectin type III-like module, and a chitin-binding domain (12 kDa). The propagation rate of S. lividans (pCHIO12) was higher in soil microcosms amended with fungal mycelia than in those containing crab chitin. Comparative biochemical and immunological studies allowed the following conclusions to be drawn. Within soil microcosm systems amended with crab shell chitin or chitin-containing Aspergillus proliferans mycelia, the strain expressed the clones exo-chiO1 gene and produced high quantities of a 59-kDa exochitinase. The enzyme was preferentially attached via its binding domain to the pellet from soil or liquid cultures. In contrast, truncated forms of 47, 40, and 25 kDa could be easily extracted from soil. The relative proportions of the 59-kDa enzyme and its truncated forms varied depending on the source of chitin and differed in soil and in liquid cultures. PMID:8633877

The biological control of Ancylostoma spp. dog infective larvae by Duddingtonia flagrans in a soil microcosm.

PubMed

Maciel, A S; Freitas, L G; Campos, A K; Lopes, E A; Araújo, J V

2010-10-29

Experiments to evaluate the potential ability of the nematode-trapping fungus Duddingtonia flagrans (Isolate CG768) to prey on the Ancylostoma spp. dog infective larvae (L(3)) in pasteurized soil were performed through several laboratory assays. A microcosm approach was used with increasing fungal concentrations in an inoculum of a chlamydospore water suspension. The highest fungal concentrations provide a more consistent larval reduction than the lowest concentrations, but no difference was observed from 10,000 to 25,000 chlamydospores per grain of soil. When using D. flagrans in a water suspension, in white rice and in milled maize, there were reductions in the larval population of 72.0%, 78.4% and 79.4%, respectively, but there was no difference between white rice and milled maize (p<0.05). To evaluate the nematode control by D. flagrans inoculated in milled maize at 10,000 chlamydospores per grain of soil under greenhouse conditions, observations were performed at 10, 15, 20, 25 and 30 days after inoculation and the percent reduction in the larval population was 61.4%, 73.2%, 70.8%, 64.5% and 57%, respectively (p<0.05). There was an inverse relationship between the number of L(3) recovered from the soil and the total days of exposure to the fungus (p<0.05). These results showed that D. flagrans could present some potential to be used as a non-chemotherapeutic alternative for regulation of Ancylostoma spp. populations in the environment. Copyright © 2010 Elsevier B.V. All rights reserved.

Clinical Laboratory Automation: A Case Study

PubMed Central

Archetti, Claudia; Montanelli, Alessandro; Finazzi, Dario; Caimi, Luigi; Garrafa, Emirena

2017-01-01

Background This paper presents a case study of an automated clinical laboratory in a large urban academic teaching hospital in the North of Italy, the Spedali Civili in Brescia, where four laboratories were merged in a unique laboratory through the introduction of laboratory automation. Materials and Methods The analysis compares the preautomation situation and the new setting from a cost perspective, by considering direct and indirect costs. It also presents an analysis of the turnaround time (TAT). The study considers equipment, staff and indirect costs. Results The introduction of automation led to a slight increase in equipment costs which is highly compensated by a remarkable decrease in staff costs. Consequently, total costs decreased by 12.55%. The analysis of the TAT shows an improvement of nonemergency exams while emergency exams are still validated within the maximum time imposed by the hospital. Conclusions The strategy adopted by the management, which was based on re-using the available equipment and staff when merging the pre-existing laboratories, has reached its goal: introducing automation while minimizing the costs. Significance for public health Automation is an emerging trend in modern clinical laboratories with a positive impact on service level to patients and on staff safety as shown by different studies. In fact, it allows process standardization which, in turn, decreases the frequency of outliers and errors. In addition, it induces faster processing times, thus improving the service level. On the other side, automation decreases the staff exposition to accidents strongly improving staff safety. In this study, we analyse a further potential benefit of automation, that is economic convenience. We study the case of the automated laboratory of one of the biggest hospital in Italy and compare the cost related to the pre and post automation situation. Introducing automation lead to a cost decrease without affecting the service level to patients

Clinical Laboratory Automation: A Case Study.

PubMed

Archetti, Claudia; Montanelli, Alessandro; Finazzi, Dario; Caimi, Luigi; Garrafa, Emirena

2017-04-13

This paper presents a case study of an automated clinical laboratory in a large urban academic teaching hospital in the North of Italy, the Spedali Civili in Brescia, where four laboratories were merged in a unique laboratory through the introduction of laboratory automation. The analysis compares the preautomation situation and the new setting from a cost perspective, by considering direct and indirect costs. It also presents an analysis of the turnaround time (TAT). The study considers equipment, staff and indirect costs. The introduction of automation led to a slight increase in equipment costs which is highly compensated by a remarkable decrease in staff costs. Consequently, total costs decreased by 12.55%. The analysis of the TAT shows an improvement of nonemergency exams while emergency exams are still validated within the maximum time imposed by the hospital. The strategy adopted by the management, which was based on re-using the available equipment and staff when merging the pre-existing laboratories, has reached its goal: introducing automation while minimizing the costs.

Mountains, Melting Pot, and Microcosm: Health Care Delay and Dengue/Zika Interplay on Hawaii Island.

PubMed

Baenziger, Nancy L

2016-11-01

Human history in the Hawaiian Islands offers a sobering study in the population dynamics of infectious disease. The indigenous population numbering an estimated half million people prior to Western contact in 1778 was reduced to less than 24,000 by 1920. Much of the decline occurred in the earliest decades after contact with Western diseases including measles, chicken pox, polio, tuberculosis, and venereal disease. A recent outbreak on the Island of Hawaii (also called the Big Island) of imported dengue fever, an illness endemic in 100 countries affecting an estimated 100-400 million people worldwide, provides insights into the problems and prospects for health care policy in managing mosquito-borne disease in a multicultural setting of geographic isolation and health care provider shortage. This incident represents in microcosm a practice run, applicable in many contexts, for an initial localized appearance of Zika virus infection, with important lessons for effective health care management in a rapidly moving and fluid arena.

Influence of water table on carbon dioxide, carbon monoxide, and methane fluxes from taiga bog microcosms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Funk, D.W.; Pullmann, E.R.; Peterson, K.M.

1994-09-01

Hydrological changes, particularly alterations in water table level, may largely overshadow the more direct effects of global temperature increase upon carbon cycling in arctic and subarctic wetlands. Frozen cores (n=40) of intact soils and vegetation were collected from a bog near Fairbanks, Alaska, and fluxes of CO{sub 2}, CH{sub 4}, and Co in response to water table variation were studied under controlled conditions in the Duke University phytotron. Core microcosms thawed to a 20-cm depth over 30 days under a 20 hour photoperiod with a day/night temperature regime of 20/10{degrees}C. After 30 days the water table in 20 microcosms wasmore » decreased from the soil surface to -15 cm and maintained at the soil surface in 20 control cores. Outward fluxes of CO{sub 2} (9-16 g m{sup -2}d{sup -1}) and CO (3-4 mg m{sup -2}d{sup -1}) were greatest during early thaw and decreased to near zero for both gases before the water table treatment started. Lower water table tripled CO{sub 2} flux to the atmosphere when compared with control cores. Carbon monoxide was emitted at low rates from high water table cores and consumed by low water table cores. Methane fluxes were low (<1 mg m{sup -2}d{sup -1}) in all cores during thaw. High water table cores increased CH{sub 4} flux to 8-9 mg m{sup -2}d{sup -1} over 70 days and remained high relative to the low water table cores (<0.74 mg m{sup -2}d{sup -1}). Although drying of wetland taiga soils may decrease CH{sub 4} emissions to the atmosphere, the associated increase in CO{sub 2} due to aerobic respiration will likely increase the global warming potential of gas emissions from these soils. 43 refs., 4 figs.« less

Zero-gravity cloud physics laboratory: Experiment program definition and preliminary laboratory concept studies

NASA Technical Reports Server (NTRS)

Eaton, L. R.; Greco, E. V.

1973-01-01

The experiment program definition and preliminary laboratory concept studies on the zero G cloud physics laboratory are reported. This program involves the definition and development of an atmospheric cloud physics laboratory and the selection and delineations of a set of candidate experiments that must utilize the unique environment of zero gravity or near zero gravity.

Ecological effects of spring and late summer applications of lambda-cyhalothrin on freshwater microcosms.

PubMed

Van Wijngaarden, R P A; Brock, T C M; van den Brink, P J; Gylstra, R; Maund, S J

2006-02-01

The aim of the study was to compare the effects of the pyrethroid insecticide lambda-cyhalothrin (treated at 10, 25, 50, 100, 250 ng active ingredient a.i./L) on a drainage ditch ecosystem in spring and late summer. Microcosms (water volume approximately 430 L) were established using enclosures in a 50-cm-deep experimental ditch system containing communities typical of macrophyte-dominated freshwater ecosystems. Effects on macroinvertebrates, zooplankton, phytoplankton, macrophytes, and community metabolism were assessed and evaluated using univariate and multivariate statistical techniques. The macroinvertebrate community responded most clearly to treatment and, as anticipated, insects and crustaceans were among the most sensitive organisms. Statistical analysis showed that the underlying community structure was significantly different between the spring and summer experiments. However, the most sensitive species (Chaoborus obscuripes and Gammarus pulex) were abundant in spring as well as in late summer. In spring and late summer, only slight and transient effects were observed at the community level in the 10-ng/L treatment. Overall, the study did not show substantial differences in the responses of sensitive taxa between spring and late summer treatments, and effects thresholds were similar irrespective of season of treatment.

Laboratory observations of biocide efficiency against Legionella in model cooling tower systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, W.M.; Eccles, J.; Fricker, C.

1999-07-01

The efficacy of specific oxidizing and non-oxidizing biocides was examined using a model cooling system inoculated with a microcosm containing an environmental isolate of Legionella pneumophila. The microcosm was prepared in a two-stage chemostat, which provided a consistent source of microbiological inoculum for the study. The microcosm consisted of both sessile (within biofilms) and planktonic Legionella in association with other microorganisms, including Pseudomonas species and cyst-forming ameobae. A procedure was established to successfully transfer the chemostat grown inoculum to the model cooling system and establish both sessile and planktonic forms of Legionella in the model cooling system. The greatest biocidalmore » effect for all of the biocides was observed immediately after dosing. This effect was relatively short-lived even for the slow acting biocides such isothiazolin (as 8 ppm active) where an effect was only observed over the first 12 hours. The faster acting biocides, DBNPA (as 8 ppm active) and gluteraldehyde (as 27 ppm active), did initially reduce Legionella populations but did not totally eliminate Legionella or provide lasting control. Chlorine and bromine (as 0.5--1.5 ppm free halogen), and ozone (as 0.1--0.5 ppm free reserve) reduced and controlled Legionella populations so long as a free reserve of oxidant was maintained. Legionella recovered quickly after biocide dosing, reestablishing similar levels to those observed before dosing.« less

A simple HPLC-DAD method for simultaneous detection of two organophosphates, profenofos and fenthion, and validation by soil microcosm experiment.

PubMed

Mahajan, Rishi; Chatterjee, Subhankar

2018-05-05

Indiscriminate use of two broad spectrum pesticides, profenofos and fenthion, in agricultural system, often results in their accumulation in a non-target niche and leaching into water bodies. The present study, therefore, aims at developing a simple and rapid HPLC method that allows simultaneous extraction and detection of these two pesticides, especially in run-off water. Extraction of the two pesticides from spiked water samples using dichloromethane resulted in recovery ranging between 80 and 90%. An HPLC run of 20 min under optimized chromatographic parameters (mobile phase: methanol (75%) and water (25%); flow rate of 0.8 ml min -1 ; diode array detector at wavelength 210 nm) resulted in a significant difference in retention times of two pesticides (4.593 min) which allows a window of opportunity to study any possible intermediates/transformants of the parent compounds while evaluating run-off waters from agricultural fields. The HPLC method developed allowed simultaneous detection of profenofos and fenthion with a single injection into the HPLC system with 0.0328 mg l -1 (32.83 ng ml -1 ) being the limit of detection (LOD) and 0.0995 mg l -1 (99.5 ng ml -1 ) as the limit of quantification (LOQ) for fenthion; for profenofos, LOD and LOQ were 0.104 mg l -1 (104.50 ng ml -1 ) and 0.316 mg l -1 (316.65 ng ml -1 ), respectively. The findings were further validated using the soil microcosm experiment that allowed simultaneous detection and quantification of profenofos and fenthion. The findings indicate towards the practical significance of the methodology developed as the soil microcosm experiment closely mimics the agricultural run-off water under natural environmental conditions.

Tethered gravity laboratories study

NASA Technical Reports Server (NTRS)

Lucchetti, F.

1989-01-01

Variable Gravity Laboratory studies are discussed. The following subject areas are covered: (1) conceptual design and engineering analysis; (2) control strategies (fast crawling maneuvers, main perturbations and their effect upon the acceleration level); and (3) technology requirements.

A temporal study on fate of Al2O3 nanoparticles in a fresh water microcosm at environmentally relevant low concentrations.

PubMed

Pakrashi, Sunandan; Dalai, Swayamprava; Ritika; Sneha, B; Chandrasekaran, N; Mukherjee, Amitava

2012-10-01

This study on a microcosm, brings out the temporal changes in physico-chemical behavior of aluminum oxide nanoparticles (for a period of 210 days), at environmentally relevant concentrations (1000 μg/L and below). The dynamics of particle behavior in terms of mean hydrodynamic diameter, specific surface area and dissolution of soluble aluminum and, their possible ecological implications have been presented in this study. A thorough statistical analysis brings out nanoparticle behavior, where a rapid aggregation of particles (79±13 nm at 0 h to 1464±80 nm at 48 h), with a decrease in specific surface area (32 m2/g at 0 h to 1.7 m2/g at 48 h) was observed. Ion release profile indicated a significant increase in soluble aluminum concentration only after 36 h (277±15 μg/L at 0 h to 462±3 μg/L at 36 h) which reduced over a period of 60 days (279±20 μg/L). A differential response at 1000 μg/L concentration was observed, short term exposure (5 days) showed an immediate effect on the resident algal population (∼25% decreased viability) and the long term (7 months/210 days) exposure showed a gradual recovery. Thus, nanomaterials may not have the stipulated toxic response, at low concentration and longer standing period, presumably owing to the complexity of the natural systems. Copyright © 2012 Elsevier Inc. All rights reserved.

Responses of aquatic insects to Cu and Zn in stream microcosms: understanding differences between single species tests and field responses.

PubMed

Clements, William H; Cadmus, Pete; Brinkman, Stephen F

2013-07-02

Field surveys of metal-contaminated streams suggest that some aquatic insects, particularly mayflies (Ephemeroptera) and stoneflies (Plecoptera), are highly sensitive to metals. However, results of single species toxicity tests indicate these organisms are quite tolerant, with LC50 values often several orders of magnitude greater than those obtained using standard test organisms (e.g., cladocerans and fathead minnows). Reconciling these differences is a critical research need, particularly since water quality criteria for metals are based primarily on results of single species toxicity tests. In this research we provide evidence based on community-level microcosm experiments to support the hypothesis that some aquatic insects are highly sensitive to metals. We present results of three experiments that quantified effects of Cu and Zn, alone and in combination, on stream insect communities. EC50 values, defined as the metal concentration that reduced abundance of aquatic insects by 50%, were several orders of magnitude lower than previously published values obtained from single species tests. We hypothesize that the short duration of laboratory toxicity tests and the failure to evaluate effects of metals on sensitive early life stages are the primary factors responsible for unrealistically high LC50 values in the literature. We also observed that Cu alone was significantly more toxic to aquatic insects than the combination of Cu and Zn, despite the fact that exposure concentrations represented theoretically similar toxicity levels. Our results suggest that water quality criteria for Zn were protective of most aquatic insects, whereas Cu was highly toxic to some species at concentrations near water quality criteria. Because of the functional significance of aquatic insects in stream ecosystems and their well-established importance as indicators of water quality, reconciling differences between field and laboratory responses and understanding the mechanisms responsible

Evaluation of aquatic plants for removing polar microcontaminants: a microcosm experiment.

PubMed

Matamoros, Víctor; Nguyen, Loc Xuan; Arias, Carlos A; Salvadó, Victòria; Brix, Hans

2012-08-01

Microcosm wetland systems (5 L containers) planted with Salvinia molesta, Lemna minor, Ceratophyllum demersum, and Elodea canadensis were investigated for the removal of diclofenac, triclosan, naproxen, ibuprofen, caffeine, clofibric acid and MCPA. After 38 days of incubation, 40-99% of triclosan, diclofenac, and naproxen were removed from the planted and unplanted reactors. In covered control reactors no removal was observed. Caffeine and ibuprofen were removed from 40% to 80% in planted reactors whereas removals in control reactors were much lower (2-30%). Removal of clofibric acid and MCPA were negligible in both planted and unplanted reactors. The findings suggested that triclosan, diclofenac, and naproxen were removed predominantly by photodegradation, whereas caffeine and naproxen were removed by biodegradation and/or plant uptake. Pseudo-first-order removal rate constants estimated from nonlinear regressions of time series concentration data were used to describe the contaminant removals. Removal rate constants ranged from 0.003 to 0.299 d(-1), with half-lives from 2 to 248 days. The formation of two major degradation products from ibuprofen, carboxy-ibuprofen and hydroxy-ibuprofen, and a photodegradation product from diclofenac, 1-(8-Chlorocarbazolyl)acetic acid, were followed as a function of time. This study emphasizes that plants contribute to the elimination capacity of microcontaminants in wetlands systems through biodegradation and uptake processes. Copyright © 2012 Elsevier Ltd. All rights reserved.

Laboratory Plasma Studies

DTIC Science & Technology

1989-05-23

Intense Rela- tivistic Electron Beams S . A Compact Accelerator Powercd by the Relativistic Klystron Amplifier T. Numerical and Experimental Studies of...Research Laboratory Washingto, IX 2075.6000 NRL Memorandum Report 6419 Megavolt, Multi-Kiloamp K - Band Gyrotron Oscillator Experiment W. M. BLACK,* S . H...Ka- Band Gyrotron Oscillator Experiments with Slotted and Unslotted Cavities S . H. GOLD, MEMBER, IEEE. A. W. FLIFLET, MEMBER, IEEE, W. M. MANHEIMER

Detection of Oxytetracycline Production by Streptomyces rimosus in Soil Microcosms by Combining Whole-Cell Biosensors and Flow Cytometry

PubMed Central

Hansen, Lars Hestbjerg; Ferrari, Belinda; Sørensen, Anders Hay; Veal, Duncan; Sørensen, Søren Johannes

2001-01-01

Combining the high specificity of bacterial biosensors and the resolution power of fluorescence-activated cell sorting (FACS) provided qualitative detection of oxytetracycline production by Streptomyces rimosus in soil microcosms. A plasmid containing a transcriptional fusion between the tetR-regulated Ptet promoter from Tn10 and a FACS-optimized gfp gene was constructed. When harbored by Escherichia coli, this plasmid produces large amounts of green fluorescent protein (GFP) in the presence of tetracycline. This tetracycline biosensor was used to detect the production of oxytetracycline by S. rimosus introduced into sterile soil. The tetracycline-induced GFP-producing biosensors were detected by FACS analysis, enabling the detection of oxytetracycline encounters by single biosensor cells. This approach can be used to study interactions between antibiotic producers and their target organisms in soil. PMID:11133451

Assessment of agglomeration, co-sedimentation and trophic transfer of titanium dioxide nanoparticles in a laboratory-scale predator-prey model system

NASA Astrophysics Data System (ADS)

Gupta, Govind Sharan; Kumar, Ashutosh; Shanker, Rishi; Dhawan, Alok

2016-08-01

Nano titanium dioxide (nTiO2) is the most abundantly released engineered nanomaterial (ENM) in aquatic environments. Therefore, it is prudent to assess its fate and its effects on lower trophic-level organisms in the aquatic food chain. A predator-and-prey-based laboratory microcosm was established using Paramecium caudatum and Escherichia coli to evaluate the effects of nTiO2. The surface interaction of nTiO2 with E. coli significantly increased after the addition of Paramecium into the microcosm. This interaction favoured the hetero-agglomeration and co-sedimentation of nTiO2. The extent of nTiO2 agglomeration under experimental conditions was as follows: combined E. coli and Paramecium > Paramecium only > E. coli only > without E. coli or Paramecium. An increase in nTiO2 internalisation in Paramecium cells was also observed in the presence or absence of E. coli cells. These interactions and nTiO2 internalisation in Paramecium cells induced statistically significant (p < 0.05) effects on growth and the bacterial ingestion rate at 24 h. These findings provide new insights into the fate of nTiO2 in the presence of bacterial-ciliate interactions in the aquatic environment.

Assessment of agglomeration, co-sedimentation and trophic transfer of titanium dioxide nanoparticles in a laboratory-scale predator-prey model system

PubMed Central

Gupta, Govind Sharan; Kumar, Ashutosh; Shanker, Rishi; Dhawan, Alok

2016-01-01

Nano titanium dioxide (nTiO2) is the most abundantly released engineered nanomaterial (ENM) in aquatic environments. Therefore, it is prudent to assess its fate and its effects on lower trophic-level organisms in the aquatic food chain. A predator-and-prey-based laboratory microcosm was established using Paramecium caudatum and Escherichia coli to evaluate the effects of nTiO2. The surface interaction of nTiO2 with E. coli significantly increased after the addition of Paramecium into the microcosm. This interaction favoured the hetero-agglomeration and co-sedimentation of nTiO2. The extent of nTiO2 agglomeration under experimental conditions was as follows: combined E. coli and Paramecium > Paramecium only > E. coli only > without E. coli or Paramecium. An increase in nTiO2 internalisation in Paramecium cells was also observed in the presence or absence of E. coli cells. These interactions and nTiO2 internalisation in Paramecium cells induced statistically significant (p < 0.05) effects on growth and the bacterial ingestion rate at 24 h. These findings provide new insights into the fate of nTiO2 in the presence of bacterial-ciliate interactions in the aquatic environment. PMID:27530102

Soil microcosm for testing the effects of chemical pollutants on soil fauna communities and trophic structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parmelee, R.W.; Wentsel, R.S.; Phillips, C.T.

1993-08-01

A microcosm technique is presented that uses community and trophic-level analysis of soil nematodes and microarthropods to determine the effects of chemicals on soil systems. Forest soil was treated with either copper, p-nitrophenol, or trinitrotoluene. Nematodes were sorted into bacterivore, fungivore, herbivore, and omnivore-predator trophic groups, and a hatchling category. Microarthropods were sorted to the acarine suborders Prostigmata, Mesostigmata, and Oribatida; the insectan order Collembola; and a miscellaneous group. Omnivore-predator nematodes and meso-stigmatid and oribatid mites were the groups most sensitive to copper and were significantly reduced at levels as low as 100 [mu]g g[sup [minus]1] copper. Total nematode andmore » microarthropod numbers declined above 200 [mu]g g[sup [minus]1] copper. Trophic structure analysis suggested that high sensitivity of nematode predators to intermediate levels of copper reduced predation on herbivore nematodes and resulted in greater numbers of nematodes compared to controls. p-Nitrophenol was very toxic to the nematode community, and all trophic groups were significantly reduced above 20 [mu]g g[sup [minus]1]. However, there was no effect of p-nitrophenol on microarthropods. Trinitrotoluene had no significant negative effect on total abundance of either groups of soil fauna, but oribatids were significantly reduced at 200 [mu]g g[sup [minus]1]. The results demonstrated that soil nematodes and microarthropods were sensitive indicators of environmental contaminants and that trophic-structure and community analysis has the potential to detect more subtle indirect effects of chemicals on soil food-web structure. The authors conclude that microcosms with field communities of soil microfauna offer high resolution of the ecotoxicological effects of chemicals in complex soil systems.« less

Effects of chronic γ-irradiation on the aquatic microbial microcosm: equi-dosimetric comparison with effects of heavy metals.

PubMed

Fuma, Shoichi; Kawaguchi, Isao; Kubota, Yoshihisa; Yoshida, Satoshi; Kawabata, Zen'ichiro; Polikarpov, Gennady G

2012-02-01

Effects of chronic γ-irradiation were investigated in the aquatic microcosm consisting of flagellate algae Euglena gracilis as producers, ciliate protozoa Tetrahymena thermophila as consumers and bacteria Escherichia coli as decomposers. At 1.1 Gy day(-1), no effects were observed. At 5.1 Gy day(-1), cell densities of E. coli showed a tendency to be lower than those of controls. At 9.7 and 24.7 Gy day(-1), population decrease was observed in E. coli. E. gracilis and T. thermophila died out after temporal population decrease and subsequent population increase in T. thermophila. It is likely that this temporal population increase was an indirect effect due to interspecies interactions. Effect dose rates of γ-rays were compared with effect concentrations of some metals using the radiochemoecological conceptual model and the effect index for microcosm. Comparison of these community-level effects data with environmental exposure data suggests that ionising radiation, gadolinium and dysprosium have low risks to affect aquatic microbial communities while manganese, nickel and copper have considerable risks. Effects of chronic irradiation were smaller than those of acute irradiation, and an acute to chronic ratio was calculated to be 28 by dividing an acute dose by chronic daily dose rate at which the effect index was 10%. This ratio would be useful for community-level extrapolation from acute to chronic radiation effects. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effect of salivary pellicle on antibacterial activity of novel antibacterial dental adhesives using a dental plaque microcosm biofilm model

PubMed Central

Li, Fang; Weir, Michael D.; Fouad, Ashraf F.; Xu, Hockin H.K.

2014-01-01

Objectives Antibacterial primer and adhesive are promising to inhibit biofilms and caries. Since restorations in vivo are exposed to saliva, one concern is the attenuation of antibacterial activity due to salivary pellicles. The objective of this study was to investigate the effects of salivary pellicles on bonding agents containing a new monomer dimethylaminododecyl methacrylate (DMADDM) or nanoparticles of silver (NAg) against biofilms for the first time. Methods DMADDM and NAg were synthesized and incorporated into Scotchbond Multi-Purpose adhesive and primer. Specimens were either coated or not coated with salivary pellicles. A microcosm biofilm model was used with mixed saliva from ten donors. Two types of culture medium were used: an artificial saliva medium (McBain), and Brain Heart Infusion (BHI) medium without salivary proteins. Metabolic activity, colony-forming units (CFU), and lactic acid production of plaque microcosm biofilms were measured (n = 6). Results Bonding agents containing DMADDM and NAg greatly inhibited biofilm activities, even with salivary pellicles. When using BHI, the pre-coating of salivary pellicles on resin surfaces significantly decreased the antibacterial effect (p < 0.05). When using artificial saliva medium, pre-coating of salivary pellicles on resin did not decrease the antibacterial effect. These results suggest that artificial saliva yielded medium-derived pellicles on resin surfaces, which provided attenuating effects on biofilms similar to salivary pellicles. Compared with the commercial control, the DMADDM-containing bonding agent reduced biofilm CFU by about two orders of magnitude. Significance Novel DMADDM- and NAg-containing bonding agents substantially reduced biofilm growth even with salivary pellicle coating on surfaces, indicating a promising usage in saliva-rich environment. DMADDM and NAg may be useful in a wide range of primers, adhesives and other restoratives to achieve antibacterial and anti

Effect of salivary pellicle on antibacterial activity of novel antibacterial dental adhesives using a dental plaque microcosm biofilm model.

PubMed

Li, Fang; Weir, Michael D; Fouad, Ashraf F; Xu, Hockin H K

2014-02-01

Antibacterial primer and adhesive are promising to inhibit biofilms and caries. Since restorations in vivo are exposed to saliva, one concern is the attenuation of antibacterial activity due to salivary pellicles. The objective of this study was to investigate the effects of salivary pellicles on bonding agents containing a new monomer dimethylaminododecyl methacrylate (DMADDM) or nanoparticles of silver (NAg) against biofilms for the first time. DMADDM and NAg were synthesized and incorporated into Scotchbond Multi-Purpose adhesive and primer. Specimens were either coated or not coated with salivary pellicles. A microcosm biofilm model was used with mixed saliva from ten donors. Two types of culture medium were used: an artificial saliva medium (McBain), and Brain Heart Infusion (BHI) medium without salivary proteins. Metabolic activity, colony-forming units (CFU), and lactic acid production of plaque microcosm biofilms were measured (n=6). Bonding agents containing DMADDM and NAg greatly inhibited biofilm activities, even with salivary pellicles. When using BHI, the pre-coating of salivary pellicles on resin surfaces significantly decreased the antibacterial effect (p<0.05). When using artificial saliva medium, pre-coating of salivary pellicles on resin did not decrease the antibacterial effect. These results suggest that artificial saliva yielded medium-derived pellicles on resin surfaces, which provided attenuating effects on biofilms similar to salivary pellicles. Compared with the commercial control, the DMADDM-containing bonding agent reduced biofilm CFU by about two orders of magnitude. Novel DMADDM- and NAg-containing bonding agents substantially reduced biofilm growth even with salivary pellicle coating on surfaces, indicating a promising usage in saliva-rich environment. DMADDM and NAg may be useful in a wide range of primers, adhesives and other restoratives to achieve antibacterial and anti-caries capabilities. Published by Elsevier Ltd.

Microbial Consortia Development and Microcosm and Column Experiments for Enhanced Bioremediation of Chlorinated Volatile Organic Compounds, West Branch Canal Creek Wetland Area, Aberdeen Proving Ground, Maryland

USGS Publications Warehouse

Lorah, Michelle M.; Majcher, Emily H.; Jones, Elizabeth J.; Voytek, Mary A.

2008-01-01

Chlorinated solvents, including 1,1,2,2-tetrachloroethane, tetrachloroethene, trichloroethene, carbon tetrachloride, and chloroform, are reaching land surface in localized areas of focused ground-water discharge (seeps) in a wetland and tidal creek in the West Branch Canal Creek area, Aberdeen Proving Ground, Maryland. In cooperation with the U.S. Army Garrison, Aberdeen Proving Ground, Maryland, the U.S. Geological Survey is developing enhanced bioremediation methods that simulate the natural anaerobic degradation that occurs without intervention in non-seep areas of the wetland. A combination of natural attenuation and enhanced bioremediation could provide a remedy for the discharging ground-water plumes that would minimize disturbance to the sensitive wetland ecosystem. Biostimulation (addition of organic substrate or nutrients) and bioaugmentation (addition of microbial consortium), applied either by direct injection at depth in the wetland sediments or by construction of a permeable reactive mat at the seep surface, were tested as possible methods to enhance anaerobic degradation in the seep areas. For the first phase of developing enhanced bioremediation methods for the contaminant mixtures in the seeps, laboratory studies were conducted to develop a microbial consortium to degrade 1,1,2,2-tetrachloroethane and its chlorinated daughter products under anaerobic conditions, and to test biostimulation and bioaugmentation of wetland sediment and reactive mat matrices in microcosms. The individual components required for the direct injection and reactive mat methods were then combined in column experiments to test them under groundwater- flow rates and contaminant concentrations observed in the field. Results showed that both direct injection and the reactive mat are promising remediation methods, although the success of direct injection likely would depend on adequately distributing and maintaining organic substrate throughout the wetland sediment in the seep

TiO2 nanoparticles for the remediation of eutrophic shallow freshwater systems: Efficiency and impacts on aquatic biota under a microcosm experiment.

PubMed

Bessa da Silva, Márcia; Abrantes, Nelson; Nogueira, Verónica; Gonçalves, Fernando; Pereira, Ruth

2016-09-01

The application of nanomaterials (NMs) in the remediation of eutrophic waters, particularly in the control of internal loading of nutrients, has been started, but limited investigations evaluated the effectiveness of these new treatment approaches and of their potential impacts on species from shallow freshwater lakes. The present work investigated, under a microcosm experiment, the application of a TiO2 nanomaterial both for reducing nutrient (mainly phosphorus and nitrogen forms) desorption and release from sediments (preventive treatment-PT) and for eliminating algal blooms (remediation treatment-RT). Furthermore, we also intended to assess the potential impacts of nano-TiO2 application on key freshwater species. The results showed the effectiveness of nano-TiO2 in controlling the release of phosphates from surface sediment and the subsequent reduction of total phosphorus in the water column. A reduction in total nitrogen was also observed. Such changes in nutrient dynamics contributed to a progressive inhibition of development of algae after the application of the NM in PT microcosms. Concerning the ability of nano-TiO2 to interact with algal cells, this interaction has likely occurred, mainly in RT, enhancing the formation of aggregates and their rapid settlement, thus reducing the algal bloom. Both treatments caused deleterious effects on freshwater species. In PT, Daphnia magna and Lemna minor showed a significant inhibition of several endpoints. Conversely, no inhibitory effect on the growth of Chironomus riparius was recorded. In opposite, C. riparius was the most affected species in RT microcosms. Such difference was probably caused by the formation of larger TiO2-algae aggregates in RT, under a high algal density, that rapidly settled in the sediment, becoming less available for pelagic species. In summary, despite the effectiveness of both treatments in controlling internal nutrient loading and in the mitigating algal bloom episodes, their negative

Effects of chemical additives on hydrocarbon disappearance and biodegradation in freshwater marsh microcosms.

PubMed

Nyman, J A; Klerks, P L; Bhattacharyya, S

2007-09-01

We determined how a cleaner and a dispersant affected hydrocarbon biodegradation in wetland soils dominated by the plant Panicum hemitomon, which occurs throughout North and South America. Microcosms received no hydrocarbons, South Louisiana crude, or diesel; and no additive, a dispersant, or a cleaner. We determined the concentration of four total petroleum hydrocarbon (TPH) measures and 43 target hydrocarbons in water and sediment fractions 1, 7, 31, and 186 days later. Disappearance was distinguished from biodegradation via hopane-normalization. After 186 days, TPH disappearance ranged from 24% to 97%. There was poor correlation among the four TPH measures, which indicated that each quantified a different suite of hydrocarbons. Hydrocarbon disappearance and biodegradation were unaltered by these additives under worse-case scenarios. Any use of these additives must generate benefits that outweigh the lack of effect on biodegradation demonstrated in this report, and the increase in toxicity that we reported earlier.

The Microcosm Mediates the Persistence of Shiga Toxin-Producing Escherichia coli in Freshwater Ecosystems

PubMed Central

Mauro, Steven A.; Opalko, Hannah; Lindsay, Kyle; Colon, Michael P.

2013-01-01

Water is a major route for infection of humans by exotoxin-producing bacteria, including Shiga toxin-producing Escherichia coli (STEC). While STEC has the potential to be present in nearly every type of water source, its distribution is sporadic, and an understanding of factors that govern its emergence and persistence within water is lacking. In this study, we examined the influence of microbe content on STEC persistence in freshwater. We found that depletion of microbes in the water leads to a considerable increase in the persistence of STEC, an effect that can be mitigated by adding grazing protists to the water. STEC strains appear to be more resistant to the impact of grazing protists than E. coli strains that lack the Shiga toxin (stx) gene. Our results demonstrate that the microcosm can dramatically influence the persistence of STEC in aquatic ecosystems and that the overall impact by microbes on STEC strains is fundamentally different from that of non-STEC strains of bacteria. Overall, these results provide insight into why STEC and possibly other exotoxin-producing bacterial pathogens display such variability in abundance, distribution, and persistence in aquatic ecosystems. PMID:23747699

Traditional and Host-Associated Fecal Indicator Bacterial Patterns in Southern California Watersheds: Field Source Identification Studies and Laboratory Microcosms Investigating Presence and Persistence in Water and Sediments

NASA Astrophysics Data System (ADS)

Mika, Kathryn Beth

microbial source tracking tools including indicator ratios and detection frequencies. Source identification studies do not necessarily have to be long-term to identify consistent sources of pollution. For example, within the first four months of sampling at Ventura, the increased frequency of detection of HF183 at the Marina Dock sample location was apparent, and a dry weather influx of HF183 was seen in the Keys channels. In addition to the many sources of FIB to the environment such as storm drains, leaking sewers, and wildlife, there are important environmental reservoirs such as sand and seaweed that can foster FIB growth and persistence in the environment. As such, it is important to understand the effect of different factors on the ability of bacteria to survive and persist in these reservoirs. Microcosm experiments conducted during the course of this dissertation research found that in dry beach sand (0.1% moisture), the addition of moisture was detrimental to the survival of the indicators studied (General Bacteroidales, E. coli, and enterococci). While increased moisture was not always detrimental to bacterial survival, these results point to the ability of bacteria to persist for long periods of time in beach environments under in-situ conditions (including dry sand). These findings point to the importance of understanding the behavior of indicator bacteria populations that have evolved to survive in environmental conditions so that their potential impact on overlying or adjacent water quality can be better understood. In summation, results from this research point to the importance of selecting indicators and sample locations that are most relevant to watershed concerns rather than using a first tier such as FIB to preferentially select sites for further analysis. Measuring a marker for human fecal pollution in both watershed studies provided useful information for potential human inputs that would have been missed if sites were chosen based on

Environmental Fate of 14C Radiolabeled 2,4-Dinitroanisole in Soil Microcosms.

PubMed

Olivares, Christopher I; Madeira, Camila L; Sierra-Alvarez, Reyes; Kadoya, Warren; Abrell, Leif; Chorover, Jon; Field, Jim A

2017-11-21

2,4-Dinitrosanisole (DNAN) is an insensitive munitions component replacing conventional explosives. While DNAN is known to biotransform in soils to aromatic amines and azo-dimers, it is seldom mineralized by indigenous soil bacteria. Incorporation of DNAN biotransformation products into soil as humus-bound material could serve as a plausible remediation strategy. The present work studied biotransformation of DNAN in soil and sludge microcosms supplemented with uniformly ring-labeled 14 C-DNAN to quantify the distribution of label in soil, aqueous, and gaseous phases. Electron donor amendments, different redox conditions (anaerobic, aerobic, sequential anaerobic-aerobic), and the extracellular oxidoreductase enzyme horseradish peroxidase (HRP) were evaluated to maximize incorporation of DNAN biotransformation products into the nonextractable soil humus fraction, humin. Irreversible humin incorporation of 14 C-DNAN occurred at higher rates in anaerobic conditions, with a moderate increase when pyruvate was added. Additionally, a single dose of HRP resulted in an instantaneous increased incorporation of 14 C-DNAN into the humin fraction. 14 C-DNAN incorporation to the humin fraction was strongly correlated (R 2 = 0.93) by the soil organic carbon (OC) amount present (either intrinsic or amended). Globally, our results suggest that DNAN biotransformation products can be irreversibly bound to humin in soils as a remediation strategy, which can be enhanced by adding soil OC.

Environmental Sciences Laboratory dedication, February 26-27, 1979

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auerbach, S.I.; Millemann, N.T.

1980-09-01

The dedication of the new Environmental Sciences Laboratory coincided with the 25th year of the establishment of the science of ecology at Oak Ridge National Laboratory. That quarter century witnessed the evolution of ecology from an obscure, backwater discipline of biology to a broadly used, everyday household word. The transition reflected broad and basic changes in our social and cultural view of the world. This was brought about as a result of the awareness developed in our society of the importance of the environment, coupled with efforts of ecologists and other environmental scientists who identified, clarified, and formulated the issuesmore » and challenges of environmental protection for both the lay public and the scientific community. In many respects, the activities in ecology at ORNL were a microcosm of the broader social scene; the particular problems of the environment associated with atomic energy needed to be defined in scientific terms and articulated in both the specific and general sense for a larger audience which was unfamiliar with the field and somewhat alien to its concepts and philosophy. The success of this effort is reflected in the existence of the new Environmental Sciences Laboratory. This dedication volume brings together the thoughts and reflections of many of these scientists whose efforts contributed in a unique and individualistic fashion not only to ORNL but also to the national identification of ecology and its importance to the achievement of our national goals. Their remarks and presentations are not only a pleasant and personally gratifying recapitulation of the past and of ORNL's contributions to ecology but also portend some of the challenges to ecology in the future.« less

Draft Test Guideline: Generic Freshwater Microcosm Test, Laboratory

EPA Pesticide Factsheets

The following draft test guideline is part of a series of test guidelines that have been developed by EPA for use in the testing of pesticides and toxic substances, and the development of test data for submission to the Agency for review.

Consortia of low-abundance bacteria drive sulfate reduction-dependent degradation of fermentation products in peat soil microcosms

DOE PAGES

Hausmann, Bela; Knorr, Klaus-Holger; Schreck, Katharina; ...

2016-03-25

A cryptic sulfur cycle and effectively competes with methanogenic degradation pathways sustains dissimilatory sulfate reduction in peatlands. In a series of peat soil microcosms incubated over 50 days, we identified bacterial consortia that responded to small, periodic additions of individual fermentation products (formate, acetate, propionate, lactate or butyrate) in the presence or absence of sulfate. Under sulfate supplementation, net sulfate turnover (ST) steadily increased to 16–174 nmol cm –3 per day and almost completely blocked methanogenesis. 16S rRNA gene and cDNA amplicon sequencing identified microorganisms whose increases in ribosome numbers strongly correlated to ST. Natively abundant (greater than or equalmore » to0.1% estimated genome abundance) species-level operational taxonomic units (OTUs) showed no significant response to sulfate. In contrast, low-abundance OTUs responded significantly to sulfate in incubations with propionate, lactate and butyrate. These OTUs included members of recognized sulfate-reducing taxa (Desulfosporosinus, Desulfopila, Desulfomonile, Desulfovibrio) and also members of taxa that are either yet unknown sulfate reducers or metabolic interaction partners thereof. The most responsive OTUs markedly increased their ribosome content but only weakly increased in abundance. Responsive Desulfosporosinus OTUs even maintained a constantly low population size throughout 50 days, which suggests a novel strategy of rare biosphere members to display activity. Interestingly, two OTUs of the non-sulfate-reducing genus Telmatospirillum (Alphaproteobacteria) showed strongly contrasting preferences towards sulfate in butyrate-amended microcosms, corroborating that closely related microorganisms are not necessarily ecologically coherent. We show that diverse consortia of low-abundance microorganisms can perform peat soil sulfate reduction, a process that exerts control on methane production in these climate-relevant ecosystems.« less

PHYSICAL AND BIOLOGICAL PARAMETERS THAT DETERMINE THE FATE OF 'P'-CHLOROPHENOL IN LABORATORY TEST SYSTEMS

EPA Science Inventory

Shake flask and microcosm studies were conducted to determine the fate of parachlorophenol (p-CP) in water and sediment systems and the role of sediment and nonsediment surfaces in the biodegradation process. Biodegradation of p-CP in estuarine water samples in shake flasks was s...

Hydrogen sulfide production by sulfate-reducing bacteria utilizing additives eluted from plastic resins.

PubMed

Tsuchida, Daisuke; Kajihara, Yusuke; Shimidzu, Nobuhiro; Hamamura, Kengo; Nagase, Makoto

2011-06-01

In the present study it was demonstrated that organic additives eluted from plastic resins could be utilized as substrates by sulfate-reducing bacteria. Two laboratory-scale experiments, a microcosm experiment and a leaching experiment, were conducted using polyvinyl chloride (PVC) as a model plastic resin. In the former experiment, the conversion of sulfate to sulfide was evident in microcosms that received plasticized PVC as the sole carbon source, but not in those that received PVC homopolymer. Additionally, dissolved organic carbon accumulated only in microcosms that received plasticized PVC, indicating that the dissolved organic carbon originated from additives. In the leaching experiment, phenol and bisphenol A were found in the leached solutions. These results suggest that the disposal of waste plastics in inert waste landfills may result in the production of H(2)S.

Biodegradation and environmental behavior of biodiesel mixtures in the sea: An initial study.

PubMed

DeMello, Jared A; Carmichael, Catherine A; Peacock, Emily E; Nelson, Robert K; Samuel Arey, J; Reddy, Christopher M

2007-07-01

Biodiesel, a mixture of fatty acid methyl esters (FAMEs) derived from animal fats or vegetable oils, is rapidly moving towards the mainstream as an alternative source of energy. However, the behavior of biodiesel, or blends of biodiesel with fossil diesel, in the marine environment have yet to be fully understood. Hence, we performed a series of initial laboratory experiments and simple calculations to evaluate the microbial and environmental fate of FAMEs. Aerobic seawater microcosms spiked with biodiesel or mixtures of biodiesel and fossil diesel revealed that the FAMEs were degraded at roughly the same rate as n-alkanes, and more rapidly than other hydrocarbon components. The residues extracted from these different microcosms became indistinguishable within weeks. Preliminary results from physical-chemical calculations suggest that FAMEs in biodiesel mixtures will not affect the evaporation rates of spilled petroleum hydrocarbons but may stabilize oil droplets in the water column and thereby facilitate transport.

Positive priming of terrestrially derived dissolved organic matter in a freshwater microcosm system

NASA Astrophysics Data System (ADS)

Bianchi, Thomas S.; Thornton, Daniel C. O.; Yvon-Lewis, Shari A.; King, Gary M.; Eglinton, Timothy I.; Shields, Michael R.; Ward, Nicholas D.; Curtis, Jason

2015-07-01

The role of priming processes in the remineralization of terrestrially derived dissolved organic carbon (TDOC) in aquatic systems has been overlooked. We provide evidence for TDOC priming using a lab-based microcosm experiment in which TDOC was primed by the addition of 13C-labeled algal dissolved organic carbon (ADOC) or a 13C-labeled disaccharide (trehalose). The rate of TDOC remineralization to carbon dioxide (CO2) occurred 4.1 ± 0.9 and 1.5 ± 0.3 times more rapidly with the addition of trehalose and ADOC, respectively, relative to experiments with TDOC as the sole carbon source over the course of a 301 h incubation period. Results from these controlled experiments provide fundamental evidence for the occurrence of priming of TDOC by ADOC and a simple disaccharide. We suggest that priming effects on TDOC should be considered in carbon budgets for large-river deltas, estuaries, lakes, hydroelectric reservoirs, and continental shelves.

Tethered gravity laboratories study

NASA Technical Reports Server (NTRS)

Lucchetti, F.

1990-01-01

The scope of the study is to investigate ways of controlling the microgravity environment of the International Space Station by means of a tethered system. Four main study tasks were performed. First, researchers analyzed the utilization of the tether systems to improve the lowest possible steady gravity level on the Space Station and the tether capability to actively control the center of gravity position in order to compensate for activities that would upset the mass distribution of the Station. The purpose of the second task was to evaluate the whole of the experiments performable in a variable gravity environment and the related beneficial residual accelerations, both for pure and applied research in the fields of fluid, materials, and life science, so as to assess the relevance of a variable g-level laboratory. The third task involves the Tethered Variable Gravity Laboratory. The use of the facility that would crawl along a deployed tether and expose experiments to varying intensities of reduced gravity is discussed. Last, a study performed on the Attitude Tether Stabilizer concept is discussed. The stabilization effect of ballast masses tethered to the Space Station was investigated as a means of assisting the attitude control system of the Station.

Human Laboratory Studies on Cannabinoids and Psychosis.

PubMed

Sherif, Mohamed; Radhakrishnan, Rajiv; D'Souza, Deepak Cyril; Ranganathan, Mohini

2016-04-01

Some of the most compelling evidence supporting an association between cannabinoid agonists and psychosis comes from controlled laboratory studies in humans. Randomized, double-blind, placebo-controlled, crossover laboratory studies demonstrate that cannabinoid agonists, including phytocannabinoids and synthetic cannabinoids, produce a wide range of positive, negative, and cognitive symptoms and psychophysiologic deficits in healthy human subjects that resemble the phenomenology of schizophrenia. These effects are time locked to drug administration, are dose related, and are transient and rarely necessitate intervention. The magnitude of effects is similar to the effects of ketamine but qualitatively distinct from other psychotomimetic drugs, including ketamine, amphetamine, and salvinorin A. Cannabinoid agonists have also been shown to transiently exacerbate symptoms in individuals with schizophrenia in laboratory studies. Patients with schizophrenia are more vulnerable than healthy control subjects to the acute behavioral and cognitive effects of cannabinoid agonists and experience transient exacerbation of symptoms despite treatment with antipsychotic medications. Furthermore, laboratory studies have failed to demonstrate any "beneficial" effects of cannabinoid agonists in individuals with schizophrenia-challenging the cannabis self-medication hypothesis. Emerging evidence suggests that polymorphisms of several genes related to dopamine metabolism (e.g., COMT, DAT1, and AKT1) may moderate the effects of cannabinoid agonists in laboratory studies. Cannabinoid agonists induce dopamine release, although the magnitude of release does not appear to be commensurate to the magnitude and spectrum of their acute psychotomimetic effects. Interactions between the endocannabinoid, gamma-aminobutyric acid, and glutamate systems and their individual and interactive effects on neural oscillations provide a plausible mechanism underlying the psychotomimetic effects of

The effect of bioturbation by Lumbriculus variegatus on transport and distribution of lead in a freshwater microcosm.

PubMed

Blankson, Emmanuel R; Klerks, Paul L

2016-05-01

The present study investigated the effect of bioturbation by the oligochaete worm Lumbriculus variegatus on the transport and environmental distribution of lead (Pb). Experiments used L. variegatus at densities of 0 ind./m(2), 2093 ind./m(2), and 8372 ind./m(2), in freshwater microcosms with Pb-spiked sediment. At the end of the 14-d experiment, Pb levels in the water column, tissues of L. variegatus, and sediment were determined, and bioturbation was quantified using luminophores. The bioturbation by L. variegatus increased Pb transport from the sediment to the water column. However, it did not significantly affect Pb bioaccumulation by L. variegatus or Pb levels in the sediment. The biodiffusion coefficient (Db) was positively related to worm density, but did not differ between Pb-spiked sediment and uncontaminated sediment. The latter finding suggests that Pb at the 100 μg/g concentration used in the present study did not affect L. variegatus bioturbation. The present study shows that bioturbation can enhance Pb transfer across the sediment-water interface and thus enhance Pb availability to organisms in the water column. © 2015 SETAC.

Use of urban composts for the regeneration of a burnt Mediterranean soil: a laboratory approach.

PubMed

Cellier, Antoine; Francou, Cédric; Houot, Sabine; Ballini, Christine; Gauquelin, Thierry; Baldy, Virginie

2012-03-01

In Mediterranean region, forest fires are a major problem leading to the desertification of the environment. Use of composts is considered as a solution for soil and vegetation rehabilitation. In this study, we determined under laboratory conditions the effects of three urban composts and their mode of application (laid on the soil surface or mixed into the soil) on soil restoration after fire: a municipal waste compost (MWC), a compost of sewage sludge mixed with green waste (SSC) and a green waste compost (GWC). Carbon (C) and nitrogen (N) mineralisation, total microbial biomass, fungal biomass and soil characteristics were measured during 77-day incubations in microcosms. The impact of composts input on hydrological behaviour related to erodibility was estimated by measuring runoff, retention and percolation (i.e. infiltration) of water using a rainfall simulator under laboratory conditions. Input of composts increased organic matter and soil nutrient content, and enhanced C and N mineralisation and total microbial biomass throughout the incubations, whereas it increased sporadically fungal biomass. For all these parameters, the MWC induced the highest improvement while GWC input had no significant effect compared to the control. Composts mixed with soil weakly limited runoff and infiltration whereas composts laid at the soil surface significantly reduced runoff and increased percolation and retention, particularly with the MWC. Copyright © 2010 Elsevier Ltd. All rights reserved.

Aquatic risk assessment of a realistic exposure to pesticides used in bulb crops: a microcosm study.

PubMed

van Wijngaarden, René P A; Cuppen, Jan G M; Arts, Gertie H P; Crum, Steven J H; van den Hoorn, Martin W; van den Brink, Paul J; Brock, Theo C M

2004-06-01

The fungicide fluazinam, the insecticide lambda-cyhalothrin, and the herbicides asulam and metamitron were applied to indoor freshwater microcosms (water volume approximately 0.6 m3). The treatment regime was based on a realistic application scenario in tulip cultivation. Concentrations of each pesticide were equal to 0%, 0.2%, 0.5%, 2%, and 5% spray drift emission of label-recommended rates. Contribution of compounds to the toxicity of the pesticide package was established by expressing their concentrations as fractions of toxic units. The fate of the compounds in the water, and responses of phytoplankton, zooplankton, periphyton, macroinvertebrates, macrophytes, decomposition, and water quality were followed for 13 weeks. The half-lives of lambda-cyhalothrin, metamitron, and fluazinam were 1 to 2 d; that of asulam was >30 d. No consistent effects could be demonstrated for the 0.2% treatment regime that was therefore considered the no-observed-effect concentration community (NOEC). The macroinvertebrate populations of Gammarus pulex, Asellus aquaticus, and Proasellus meridianus were the most sensitive end points, followed by species of copepods and cladocerans. Responses mainly were due to lambda-cyhalothrin. The 0.5% treatment regime resulted in short-term effects. Pronounced effects were observed at the 2% and 5% treatment levels. At the end of the experiment, the macrophyte biomass that consisted of Elodea nuttallii, showed a decline at the two highest treatment levels, asulam being the causal factor (NOEC: 0.5% treatment level). Primary production was reduced at the 5% treatment level only. In our experiment, the first-tier risk assessment procedure for individual compounds was adequate for protecting sensitive populations exposed to realistic combinations of pesticides. Spray drift reduction measures seem to be efficient in protecting aquatic ecosystems in agricultural areas.

Genetically engineered Pseudomonas putida X3 strain and its potential ability to bioremediate soil microcosms contaminated with methyl parathion and cadmium.

PubMed

Zhang, Rong; Xu, Xingjian; Chen, Wenli; Huang, Qiaoyun

2016-02-01

A multifunctional Pseudomonas putida X3 strain was successfully engineered by introducing methyl parathion (MP)-degrading gene and enhanced green fluorescent protein (EGFP) gene in P. putida X4 (CCTCC: 209319). In liquid cultures, the engineered X3 strain utilized MP as sole carbon source for growth and degraded 100 mg L(-1) of MP within 24 h; however, this strain did not further metabolize p-nitrophenol (PNP), an intermediate metabolite of MP. No discrepancy in minimum inhibitory concentrations (MICs) to cadmium (Cd), copper (Cu), zinc (Zn), and cobalt (Co) was observed between the engineered X3 strain and its host strain. The inoculated X3 strain accelerated MP degradation in different polluted soil microcosms with 100 mg MP kg(-1) dry soil and/or 5 mg Cd kg(-1) dry soil; MP was completely eliminated within 40 h. However, the presence of Cd in the early stage of remediation slightly delayed MP degradation. The application of X3 strain in Cd-contaminated soil strongly affected the distribution of Cd fractions and immobilized Cd by reducing bioavailable Cd concentrations with lower soluble/exchangeable Cd and organic-bound Cd. The inoculated X3 strain also colonized and proliferated in various contaminated microcosms. Our results suggested that the engineered X3 strain is a potential bioremediation agent showing competitive advantage in complex contaminated environments.

Case Studies in Sustainability Used in an Introductory Laboratory Course to Enhance Laboratory Instruction

ERIC Educational Resources Information Center

Luster-Teasley, Stephanie; Hargrove-Leak, Sirena; Gibson, Willietta; Leak, Roland

2017-01-01

This educational research seeks to develop novel laboratory modules by using Case Studies in the Science Teaching method to introduce sustainability and environmental engineering laboratory concepts to 21st century learners. The increased interest in "going green" has led to a surge in the number of engineering students studying…

Effects of N and P fertilisation on greenhouse gas (GHG) production in floodplain fen peat: A microcosm fertilisation experiment.

NASA Astrophysics Data System (ADS)

Stanley, Kieran; Heppell, Catherine; Belyea, Lisa; Baird, Andrew

2016-04-01

CH4 production. Samples fertilised with P+G had the highest CH4 production (ANCOVA, between factors: treatment and site; covariate: time; F4,120= 15.026, p < 0.001). Samples fertilised with N (N+G and N+P+G) showed CH4 inhibition in comparison to G and P+G additions. CH4 production was significantly greater from the nutrient-rich peat than from the lower-nutrient peat (ANCOVA, between factors: treatment and site; covariate: time; F1,120= 38.646, p < 0.01). However, a decline in CH4 concentration in the microcosms suggests that CH4 oxidation occurred after 150 hours at the lower-nutrient site. Owing to the anaerobic conditions within the microcosms, aerobic methanotrophy cannot occur, suggesting anaerobic CH4 oxidation occurred along with denitrification. However, NO and N2 concentrations were not measured in this study, so this suggestion requires examination in future work.

Fate of microbial metabolites of hydrocarbons in a coastal plain aquifer: The role of electron acceptors

USGS Publications Warehouse

Cozzarelli, I.M.; Herman, J.S.; Baedecker, M. Jo

1995-01-01

A combined field and laboratory study was undertaken to understand the distribution and geochemical conditions that influence the prevalence of low molecular weight organic acids in groundwater of a shallow aquifer contaminated with gasoline. Aromatic hydrocarbons from gasoline were degraded by microbially mediated oxidation-reduction reactions, including reduction of nitrate, sulfate, and Fe(III). The biogeochemical reactions changed overtime in response to changes in the hydrogeochemical conditions in the aquifer. Aliphatic and aromatic organic acids were associated with hydrocarbon degradation in anoxic zones of the aquifer. Laboratory microcosms demonstrated that the biogeochemical fate of specific organic acids observed in groundwater varied with the structure of the acid and the availability of electron acceptors. Benzoic and phenylacetic acid were degraded by indigenous aquifer microorganisms when nitrate was supplied as an electron acceptor. Aromatic acids with two or more methyl substituants on the benzene ring persisted under nitrate-reducing conditions. Although iron reduction and sulfate reduction were important processes in situ and occurred in the microcosms, these reactions were not coupled to the biological oxidation of aromatic organic acids that were added to the microcosms as electron donors. ?? 1995 American Chemical Society.

In situ determination of the effects of lead and copper on cyanobacterial populations in microcosms.

PubMed

Burnat, Mireia; Diestra, Elia; Esteve, Isabel; Solé, Antonio

2009-07-10

Biomass has been studied as biomarker to evaluate the effect of heavy metals on microbial communities. Nevertheless, the most important methodological problem when working with natural and artificial microbial mats is the difficulty to evaluate changes produced on microorganism populations that are found in thicknesses of just a few mm depth. Here, we applied for first time a recently published new method based on confocal laser scanning microscopy and image-program analysis to determine in situ the effect of Pb and Cu stress in cyanobacterial populations. The results showed that both in the microcosm polluted by Cu and by Pb, a drastic reduction in total biomass for cyanobacterial and Microcoleus sp. (the dominant filamentous cyanobacterium in microbial mats) was detected within a week. According to the data presented in this report, this biomass inspection has a main advantage: besides total biomass, diversity, individual biomass of each population and their position can be analysed at microscale level. CLSM-IA could be a good method for analyzing changes in microbial biomass as a response to the addition of heavy metals and also to other kind of pollutants.

Effects of cadmium and resource quality on freshwater detritus processing chains: a microcosm approach with two insect species.

PubMed

Campos, Diana; Alves, Artur; Lemos, Marco F L; Correia, António; Soares, Amadeu M V M; Pestana, João L T

2014-07-01

Detritus processing is vital for freshwater ecosystems that depend on the leaf litter from riparian vegetation and is mediated by microorganisms and aquatic invertebrates. Shredder invertebrates transform coarse particulate organic matter into fine particulate organic matter used as food by collector species. Direct and indirect effects of contaminants can impair detritus processing and thus affect the functioning of these ecosystems. Here, we assessed the combined effects of a toxic metal (cadmium) and resource quality (leaf species) on detritus processing and shredder-collector interactions. We considered two types of leaves, alder and eucalyptus that were microbially conditioned under different Cd concentrations in the laboratory. The microbial communities present on leaves were analyzed by Denaturing Gradient Gel Electrophoresis (DGGE), and we also measured microbial respiration rates. Sericostoma vittatum (a caddisfly shredder) and Chironomus riparius (a midge collector) were also exposed to Cd and allowed to consume the corresponding alder or eucalyptus leaves. We evaluated C. riparius growth and leaf mass loss in multispecies microcosms. Cadmium exposure affected leaf conditioning and fungal diversity on both leaf species, as assessed by DGGE. Cadmium exposure also affected the mass loss of alder leaves by reductions in detritivore feeding, and impaired C. riparius growth. Chironomus riparius consumed alder leaf discs in the absence of shredders, but S. vittatum appear to promote C. riparius growth in treatments containing eucalyptus. These results show that indirect effects of contaminants along detritus-processing chains can occur through effects on shredder-collector interactions such as facilitation but they also depend on the nutritional quality of detritus and on sensitivity and feeding plasticity of detritivore species.

Effects of Nitrogen Addition on Litter Decomposition and CO2 Release: Considering Changes in Litter Quantity

PubMed Central

Li, Hui-Chao; Hu, Ya-Lin; Mao, Rong; Zhao, Qiong; Zeng, De-Hui

2015-01-01

This study aims to evaluate the impacts of changes in litter quantity under simulated N deposition on litter decomposition, CO2 release, and soil C loss potential in a larch plantation in Northeast China. We conducted a laboratory incubation experiment using soil and litter collected from control and N addition (100 kg ha−1 year−1 for 10 years) plots. Different quantities of litter (0, 1, 2 and 4 g) were placed on 150 g soils collected from the same plots and incubated in microcosms for 270 days. We found that increased litter input strongly stimulated litter decomposition rate and CO2 release in both control and N fertilization microcosms, though reduced soil microbial biomass C (MBC) and dissolved inorganic N (DIN) concentration. Carbon input (C loss from litter decomposition) and carbon output (the cumulative C loss due to respiration) elevated with increasing litter input in both control and N fertilization microcosms. However, soil C loss potentials (C output–C input) reduced by 62% in control microcosms and 111% in N fertilization microcosms when litter addition increased from 1 g to 4 g, respectively. Our results indicated that increased litter input had a potential to suppress soil organic C loss especially for N addition plots. PMID:26657180

[External quality assessment in clinical biochemistry laboratories: pilot study in 11 laboratories of Lomé (Togo)].

PubMed

Kouassi, Kafui; Fétéké, Lochina; Assignon, Selom; Dorkenoo, Ameyo; Napo-Koura, Gado

2015-01-01

This study aims to evaluate the performance of a few biochemistry analysis and make recommendations to the place of the stakeholders. It is a cross-sectional study conducted between the October 1(st), 2012 and the July 31, 2013 bearing on the results of 5 common examinations of clinical biochemistry, provided by 11 laboratories volunteers opening in the public and private sectors. These laboratories have analysed during the 3 cycles, 2 levels (medium and high) of serum concentration of urea, glucose, creatinine and serum aminotransferases. The performance of laboratories have been determined from the acceptable limits corresponding to the limits of total errors, defined by the French Society of Clinical Biology (SFBC). A system of internal quality control is implemented by all laboratories and 45% of them participated in international programs of external quality assessment (EQA). The rate of acceptable results for the entire study was of 69%. There was a significant difference (p<0.002) between the performance of the group of laboratories engaged in a quality approach and the group with default implementation of the quality approach. Also a significant difference was observed between the laboratories of the central level and those of the peripheral level of our health system (p<0.047). The performance of the results provided by the laboratories remains relatively unsatisfactory. It is important that the Ministry of Health put in place a national program of EQA with mandatory participation.

Aquatic toxicity of ivermectin in cattle dung assessed using microcosms.

PubMed

Mesa, Leticia M; Lindt, I; Negro, L; Gutierrez, M F; Mayora, G; Montalto, L; Ballent, M; Lifschitz, A

2017-10-01

Ivermectin (IVM) is a parasiticide widely used for livestock. It is a semisynthetic derivative of avermectin, a macrocyclic lactone produced by Streptomyces avermitilis. This drug is only partly metabolized by livestock; considerable amounts of parent drug are excreted mostly via feces. To simulate exposure of aquatic invertebrates and macrophytes to direct excretion of cattle dung into surface waters, a microcosm experiment with IVM spiked in cattle dung was conducted. The objectives of this study were to characterize accumulation of IVM in water, sediment+dung, roots of the floating fern Salvinia and the zooplankton Ceriodaphnia dubia, the amphipod Hyalella and the apple snail Pomacea; to determine the effect of this drug spiked in cattle dung on life-history traits of these invertebrates; and to evaluate the influence of IVM on aquatic nutrient cycling. Dung was spiked with IVM to attain concentrations of 1150, 458, 50 and 22µgkg -1 dung fresh weight, approximating those found in cattle dung at days 3, 7, 16 and 29 following subcutaneous injection. Concentrations found in dung during the first week of excretion were lethally toxic to Ceriodaphnia dubia and Hyalella, whereas no mortality was observed in Pomacea. Concentrations of IVM in roots, sediment + dung and Pomacea increased significantly from the lowest to the highest treatment level. The effect of this drug on decomposition and release of nutrients from dung would have negative consequences for nutrient cycling in water. Increasing concentrations in sediment + dung with days of the experiment suggested that toxic concentrations would persist for an extended period in the water-sediment system. IVM represents an ecological risk for aquatic ecosystems, underscoring the need for livestock management strategies to limit its entry into water bodies. Copyright © 2017 Elsevier Inc. All rights reserved.

Impact of Deepwater Horizon Oil Contamination on the Aqueous Geochemistry of Salt Marsh Sediment/Seawater Microcosms

NASA Astrophysics Data System (ADS)

Rentschler, E. K.; Donahoe, R. J.

2011-12-01

On April 20th, 2010, the Deepwater Horizon oil drilling rig, located in the Gulf of Mexico about 41 miles off the Louisiana coast, exploded, burned for two days, and sank. Approximately 4.9 million gallons of crude oil were released and traveled with ocean currents to reach the coasts of Louisiana, Mississippi, Alabama, and Florida. Previous studies have primarily considered the direct impact of oil and dispersant contamination on coastal ecosystems, but have not examined the potential impact of the accident on the inorganic geochemistry of coastal waters and sediments. In this study, microcosm experiments were conducted to determine how oil contamination will affect the concentration and distribution of trace elements in a salt marsh environment. Uncontaminated sediment and seawater, collected from a salt marsh at Bayou la Batre, Alabama, were measured into jars and spiked with 500 ppm MC-252 oil. Twenty jars, including duplicates and both sterile and non-sterile controls, were placed on a shaker table at 100 rpm. The jars were sacrificed at predetermined time intervals (0 h, 6 h, 12 h, 24 h, 48 h, 7 d, and 14 d), and the aqueous samples prepared for analysis by ICP-OES and IC. The pH for the water in the time series experiment ranged from 7.16 to 8.06. Seawater alkalinity was measured at 83.07 mg CaCO3/L. ICP-OES data show variations in aqueous element concentrations over the 14 day microcosm experiment. Significant positive correlations (>0.75) were found for the following pairs of elements: calcium and magnesium, calcium and sodium, magnesium and sodium, silica and boron, beryllium and boron, iron and silica, manganese and silica, boron and manganese, arsenic and nickel, beryllium and selenium, beryllium and zinc, copper and chloride, bromide and sulfate. Aqueous iron concentrations were highly correlated with solution pH. The presence of iron oxide and clays in the sediment indicates a potential for adsorption of trace elements sourced from the environment and

Site-specific variability in BTEX biodegradation under denitrifying conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kao, C.M.; Borden, R.C.

1997-03-01

Laboratory microcosm experiments were conducted to evaluate the feasibility of benzene, toluene, ethylbenzene, m-xylene, and o-xylene (BTEX) biodegradation under denitrifying conditions. Nine different sources of inocula, including contaminated and uncontaminated soil cores from four different sites and activated sludge, were used to establish microcosms. BTEX was not degraded under denitrifying conditions in microcosms inoculated with aquifer material from Rocky Point and Traverse City. However, rapid depletion of glucose under denitrifying conditions was observed in microcosms containing Rocky Point aquifer material. TEX degradation was observed in microcosms containing Rocky Point aquifer material. TEX degradation was observed in microcosms containing aquifer materialmore » from Fort Bragg and Sleeping Bear Dunes and sewage sludge. Benzene was recalcitrant in all microcosms tested. The degradation of o-xylene ceased after toluene, ethylbenzene, and m-xylene were depleted in the Fort Bragg and sludge microcosms, but o-xylene continued to degrade in microcosms with contaminated Sleeping Bear Dunes soil. The most probable number (MPN) of denitrifiers in these nine different inocula were measured using a microtiter technique. There was no correlation between the MPN of denitrifiers and the TEX degradation rate under denitrifying conditions. Experimental results indicate that the degradation sequence and TEX degradation rate under denitrifying conditions may differ among sites. Results also indicate that denitrification alone may not be a suitable bioremediation technology for gasoline-contaminated aquifers because of the inability of denitrifiers to degrade benzene.« less

Standardization of Laboratory Methods for the PERCH Study

PubMed Central

Karron, Ruth A.; Morpeth, Susan C.; Bhat, Niranjan; Levine, Orin S.; Baggett, Henry C.; Brooks, W. Abdullah; Feikin, Daniel R.; Hammitt, Laura L.; Howie, Stephen R. C.; Knoll, Maria Deloria; Kotloff, Karen L.; Madhi, Shabir A.; Scott, J. Anthony G.; Thea, Donald M.; Adrian, Peter V.; Ahmed, Dilruba; Alam, Muntasir; Anderson, Trevor P.; Antonio, Martin; Baillie, Vicky L.; Dione, Michel; Endtz, Hubert P.; Gitahi, Caroline; Karani, Angela; Kwenda, Geoffrey; Maiga, Abdoul Aziz; McClellan, Jessica; Mitchell, Joanne L.; Morailane, Palesa; Mugo, Daisy; Mwaba, John; Mwansa, James; Mwarumba, Salim; Nyongesa, Sammy; Panchalingam, Sandra; Rahman, Mustafizur; Sawatwong, Pongpun; Tamboura, Boubou; Toure, Aliou; Whistler, Toni; O’Brien, Katherine L.; Murdoch, David R.

2017-01-01

Abstract The Pneumonia Etiology Research for Child Health study was conducted across 7 diverse research sites and relied on standardized clinical and laboratory methods for the accurate and meaningful interpretation of pneumonia etiology data. Blood, respiratory specimens, and urine were collected from children aged 1–59 months hospitalized with severe or very severe pneumonia and community controls of the same age without severe pneumonia and were tested with an extensive array of laboratory diagnostic tests. A standardized testing algorithm and standard operating procedures were applied across all study sites. Site laboratories received uniform training, equipment, and reagents for core testing methods. Standardization was further assured by routine teleconferences, in-person meetings, site monitoring visits, and internal and external quality assurance testing. Targeted confirmatory testing and testing by specialized assays were done at a central reference laboratory. PMID:28575358

[Quality Management and Quality Specifications of Laboratory Tests in Clinical Studies--Challenges in Pre-Analytical Processes in Clinical Laboratories].

PubMed

Ishibashi, Midori

2015-01-01

The cost, speed, and quality are the three important factors recently indicated by the Ministry of Health, Labour and Welfare (MHLW) for the purpose of accelerating clinical studies. Based on this background, the importance of laboratory tests is increasing, especially in the evaluation of clinical study participants' entry and safety, and drug efficacy. To assure the quality of laboratory tests, providing high-quality laboratory tests is mandatory. For providing adequate quality assurance in laboratory tests, quality control in the three fields of pre-analytical, analytical, and post-analytical processes is extremely important. There are, however, no detailed written requirements concerning specimen collection, handling, preparation, storage, and shipping. Most laboratory tests for clinical studies are performed onsite in a local laboratory; however, a part of laboratory tests is done in offsite central laboratories after specimen shipping. As factors affecting laboratory tests, individual and inter-individual variations are well-known. Besides these factors, standardizing the factors of specimen collection, handling, preparation, storage, and shipping, may improve and maintain the high quality of clinical studies in general. Furthermore, the analytical method, units, and reference interval are also important factors. It is concluded that, to overcome the problems derived from pre-analytical processes, it is necessary to standardize specimen handling in a broad sense.

Indirect Evidence Link PCB Dehalogenation with Geobacteraceae in Anaerobic Sediment-Free Microcosms

PubMed Central

Praveckova, Martina; Brennerova, Maria V.; Holliger, Christof; De Alencastro, Felippe; Rossi, Pierre

2016-01-01

Although polychlorinated biphenyls (PCBs) production was brought to a halt 30 years ago, recalcitrance to degradation makes them a major environmental pollutant at a global scale. Previous studies confirmed that organohalide-respiring bacteria (OHRB) were capable of utilizing chlorinated congeners as electron acceptor. OHRB belonging to the Phyla Chloroflexi and Firmicutes are nowadays considered as the main PCB-dechlorinating organisms. In this study, we aimed at exploring the involvement of other taxa in PCB dechlorination using sediment-free microcosms (SFMs) and the Delor PCB mixture. High rates of congener dehalogenation (up to 96%) were attained in long-term incubations of up to 692 days. Bacterial communities were dominated by Chloroflexi, Proteobacteria, and Firmicutes, among strictly simplified community structures composed of 12 major phyla only. In a first batch of SFMs, Dehalococcoides mccartyi closely affiliated with strains CG4 and CBDB1 was considered as the main actor associated with congener dehalogenation. Addition of 2-bromoethanesulfonate (BES), a known inhibitor of methanogenic activity in a second batch of SFMs had an adverse effect on the abundance of Dehalococcoides sp. Only two sequences affiliated to this Genus could be detected in two (out of six) BES-treated SFMs, contributing to a mere 0.04% of the communities. BES-treated SFMs showed very different community structures, especially in the contributions of organisms involved in fermentation and syntrophic activities. Indirect evidence provided by both statistical and phylogenetic analysis validated the implication of a new cluster of actors, distantly affiliated with the Family Geobacteraceae (Phylum δ-Proteobacteria), in the dehalogenation of low chlorinated PCB congeners. Members of this Family are known already for their dehalogenation capacity of chlorinated solvents. As a result, the present study widens the knowledge for the phylogenetic reservoir of indigenous PCB dechlorinating

Indirect Evidence Link PCB Dehalogenation with Geobacteraceae in Anaerobic Sediment-Free Microcosms.

PubMed

Praveckova, Martina; Brennerova, Maria V; Holliger, Christof; De Alencastro, Felippe; Rossi, Pierre

2016-01-01

Although polychlorinated biphenyls (PCBs) production was brought to a halt 30 years ago, recalcitrance to degradation makes them a major environmental pollutant at a global scale. Previous studies confirmed that organohalide-respiring bacteria (OHRB) were capable of utilizing chlorinated congeners as electron acceptor. OHRB belonging to the Phyla Chloroflexi and Firmicutes are nowadays considered as the main PCB-dechlorinating organisms. In this study, we aimed at exploring the involvement of other taxa in PCB dechlorination using sediment-free microcosms (SFMs) and the Delor PCB mixture. High rates of congener dehalogenation (up to 96%) were attained in long-term incubations of up to 692 days. Bacterial communities were dominated by Chloroflexi, Proteobacteria, and Firmicutes, among strictly simplified community structures composed of 12 major phyla only. In a first batch of SFMs, Dehalococcoides mccartyi closely affiliated with strains CG4 and CBDB1 was considered as the main actor associated with congener dehalogenation. Addition of 2-bromoethanesulfonate (BES), a known inhibitor of methanogenic activity in a second batch of SFMs had an adverse effect on the abundance of Dehalococcoides sp. Only two sequences affiliated to this Genus could be detected in two (out of six) BES-treated SFMs, contributing to a mere 0.04% of the communities. BES-treated SFMs showed very different community structures, especially in the contributions of organisms involved in fermentation and syntrophic activities. Indirect evidence provided by both statistical and phylogenetic analysis validated the implication of a new cluster of actors, distantly affiliated with the Family Geobacteraceae (Phylum δ-Proteobacteria), in the dehalogenation of low chlorinated PCB congeners. Members of this Family are known already for their dehalogenation capacity of chlorinated solvents. As a result, the present study widens the knowledge for the phylogenetic reservoir of indigenous PCB dechlorinating

Degradation and metabolite formation of estrogen conjugates in an agricultural soil

USDA-ARS?s Scientific Manuscript database

Estrogen conjugates are precursors of free estrogens such as 17beta-estradiol (E2) and estrone (E1), which causes potent endocrine disrupting effects on aquatic organisms. In this study, microcosm laboratory experiments were conducted in an agricultural soil to investigate the aerobic degradation an...

Ammonia concentration determines differential growth of ammonia-oxidising archaea and bacteria in soil microcosms.

PubMed

Verhamme, Daniel T; Prosser, James I; Nicol, Graeme W

2011-06-01

The first step of nitrification, oxidation of ammonia to nitrite, is performed by both ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) in soil, but their relative contributions to ammonia oxidation and existence in distinct ecological niches remain to be determined. To determine whether available ammonia concentration has a differential effect on AOA and AOB growth, soil microcosms were incubated for 28 days with ammonium at three concentrations: native (control), intermediate (20 μg NH(4)(+)-N per gram of soil) and high (200 μg NH(4)(+)-N per gram of soil). Quantitative PCR demonstrated growth of AOA at all concentrations, whereas AOB growth was prominent only at the highest concentration. Similarly, denaturing gradient gel electrophoresis (DGGE) analysis revealed changes in AOA communities at all ammonium concentrations, whereas AOB communities changed significantly only at the highest ammonium concentration. These results provide evidence that ammonia concentration contributes to the definition of distinct ecological niches of AOA and AOB in soil.

Ammonia concentration determines differential growth of ammonia-oxidising archaea and bacteria in soil microcosms

PubMed Central

Verhamme, Daniel T; Prosser, James I; Nicol, Graeme W

2011-01-01

The first step of nitrification, oxidation of ammonia to nitrite, is performed by both ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) in soil, but their relative contributions to ammonia oxidation and existence in distinct ecological niches remain to be determined. To determine whether available ammonia concentration has a differential effect on AOA and AOB growth, soil microcosms were incubated for 28 days with ammonium at three concentrations: native (control), intermediate (20 μg NH4+-N per gram of soil) and high (200 μg NH4+-N per gram of soil). Quantitative PCR demonstrated growth of AOA at all concentrations, whereas AOB growth was prominent only at the highest concentration. Similarly, denaturing gradient gel electrophoresis (DGGE) analysis revealed changes in AOA communities at all ammonium concentrations, whereas AOB communities changed significantly only at the highest ammonium concentration. These results provide evidence that ammonia concentration contributes to the definition of distinct ecological niches of AOA and AOB in soil. PMID:21228892

Diverse Reductive Dehalogenases Are Associated with Clostridiales-Enriched Microcosms Dechlorinating 1,2-Dichloroethane

PubMed Central

Merlino, Giuseppe; Marzorati, Massimo; Rizzi, Aurora; Lavazza, Davide; de Ferra, Francesca; Carpani, Giovanna

2015-01-01

The achievement of successful biostimulation of active microbiomes for the cleanup of a polluted site is strictly dependent on the knowledge of the key microorganisms equipped with the relevant catabolic genes responsible for the degradation process. In this work, we present the characterization of the bacterial community developed in anaerobic microcosms after biostimulation with the electron donor lactate of groundwater polluted with 1,2-dichloroethane (1,2-DCA). Through a multilevel analysis, we have assessed (i) the structural analysis of the bacterial community; (ii) the identification of putative dehalorespiring bacteria; (iii) the characterization of functional genes encoding for putative 1,2-DCA reductive dehalogenases (RDs). Following the biostimulation treatment, the structure of the bacterial community underwent a notable change of the main phylotypes, with the enrichment of representatives of the order Clostridiales. Through PCR targeting conserved regions within known RD genes, four novel variants of RDs previously associated with the reductive dechlorination of 1,2-DCA were identified in the metagenome of the Clostridiales-dominated bacterial community. PMID:26273600

A multiple testing approach for hazard evaluation of complex mixtures in the aquatic environment: the use of diesel oil as a model

USGS Publications Warehouse

Johnson, B. Thomas

1989-01-01

Traditional single species toxicity tests and multiple component laboratory-scaled microcosm assays were combined to assess the toxicological hazard of diesel oil, a model complex mixture, to a model aquatic environment. The immediate impact of diesel oil dosed on a freshwater community was studied in a model pond microcosm over 14 days: a 7-day dosage and a 7-day recovery period. A multicomponent laboratory microcosm was designed to monitor the biological effects of diesel oil (1·0 mg litre−1) on four components: water, sediment (soil + microbiota), plants (aquatic macrophytes and algae), and animals (zooplanktonic and zoobenthic invertebrates). To determine the sensitivity of each part of the community to diesel oil contamination and how this model community recovered when the oil dissipated, limnological, toxicological, and microbiological variables were considered. Our model revealed these significant occurrences during the spill period: first, a community production and respiration perturbation, characterized in the water column by a decrease in dissolved oxygen and redox potential and a concomitant increase in alkalinity and conductivity; second, marked changes in microbiota of sediments that included bacterial heterotrophic dominance and a high heterotrophic index (0·6), increased bacterial productivity, and the marked increases in numbers of saprophytic bacteria (10 x) and bacterial oil degraders (1000 x); and third, column water acutely toxic (100% mortality) to two model taxa: Selenastrum capricornutum and Daphnia magna. Following the simulated clean-up procedure to remove the oil slick, the recovery period of this freshwater microcosm was characterized by a return to control values. This experimental design emphasized monitoring toxicological responses in aquatic microcosm; hence, we proposed the term ‘toxicosm’ to describe this approach to aquatic toxicological hazard evaluation. The toxicosm as a valuable toxicological tool for screening

Degradation Network Reconstruction in Uric Acid and Ammonium Amendments in Oil-Degrading Marine Microcosms Guided by Metagenomic Data

PubMed Central

Bargiela, Rafael; Gertler, Christoph; Magagnini, Mirko; Mapelli, Francesca; Chen, Jianwei; Daffonchio, Daniele; Golyshin, Peter N.; Ferrer, Manuel

2015-01-01

Biostimulation with different nitrogen sources is often regarded as a strategy of choice in combating oil spills in marine environments. Such environments are typically depleted in nitrogen, therefore limiting the balanced microbial utilization of carbon-rich petroleum constituents. It is fundamental, yet only scarcely accounted for, to analyze the catabolic consequences of application of biostimulants. Here, we examined such alterations in enrichment microcosms using sediments from chronically crude oil-contaminated marine sediment at Ancona harbor (Italy) amended with natural fertilizer, uric acid (UA), or ammonium (AMM). We applied the web-based AromaDeg resource using as query Illumina HiSeq meta-sequences (UA: 27,893 open reading frames; AMM: 32,180) to identify potential catabolic differences. A total of 45 (for UA) and 65 (AMM) gene sequences encoding key catabolic enzymes matched AromaDeg, and their participation in aromatic degradation reactions could be unambiguously suggested. Genomic signatures for the degradation of aromatics such as 2-chlorobenzoate, indole-3-acetate, biphenyl, gentisate, quinoline and phenanthrene were common for both microcosms. However, those for the degradation of orcinol, ibuprofen, phenylpropionate, homoprotocatechuate and benzene (in UA) and 4-aminobenzene-sulfonate, p-cumate, dibenzofuran and phthalate (in AMM), were selectively enriched. Experimental validation was conducted and good agreement with predictions was observed. This suggests certain discrepancies in action of these biostimulants on the genomic content of the initial microbial community for the catabolism of petroleum constituents or aromatics pollutants. In both cases, the emerging microbial communities were phylogenetically highly similar and were composed by very same proteobacterial families. However, examination of taxonomic assignments further revealed different catabolic pathway organization at the organismal level, which should be considered for designing

An assessment of natural biotransformation of petroleum hydrocarbons and chlorinated solvents at an aquifer plume transect

NASA Astrophysics Data System (ADS)

Skubal, Karen L.; Barcelona, Michael J.; Adriaens, Peter

2001-05-01

Field biogeochemical characterization and laboratory microcosm studies were performed to assess the potential for future biotransformation of trichloroethylene (TCE) and toluene in a plume containing petroleum hydrocarbons and chlorinated solvents at the former Wurtsmith Air Force Base in Oscoda, MI. In situ terminal electron accepting processes (TEAPs), contaminant composition and microbial phylogeny were studied at a plume transect 100 m downgradient of the source. The presence of reduced electron acceptors, relevant microbial communities, and elevated dissolved methane and carbon dioxide concentrations at the transect, as well as downgradient accumulation of BTEX metabolites and dechlorination products, indicated that past or current reductive dechlorination at the transect was likely driven by BTEX biodegradation in the methanogenic zone. However, TCE and toluene mineralization in sediment-groundwater microcosms without added electron acceptors did not exceed 5% during 300 days of incubation and was nearly invariant with original sediment TEAP, even following amendments of nitrogen and phosphorus. Mineralization rates were on the order of 0.0015-0.03 μmol/g day. After 8 months, microcosms showed evidence of methanogenesis, but CH 4 and CO 2 production arose from the degradation of contaminants other than toluene. Cis-dichloroethylene was observed in only one methanogenic microcosm after more than 500 days. It appears likely that spatially and temporally dynamic redox zonation at the plume transect will prevent future sustained reductive dehalogenation of highly chlorinated solvents, for during the course of a year, the predominant TEAP at the highly contaminated water table shifted from methanogenesis to iron- and sulfate-reduction. It is recommended that biotransformation studies combine considerations of long-term, spatially relevant changes in redox zonation with laboratory-scale studies of electron donor utilization and cometabolic substrate transformation

Assessing local planning to control groundwater depletion: California as a microcosm of global issues

NASA Astrophysics Data System (ADS)

Nelson, Rebecca L.

2012-01-01

Groundwater pumping has caused excessive groundwater depletion around the world, yet regulating pumping remains a profound challenge. California uses more groundwater than any other U.S. state, and serves as a microcosm of the adverse effects of pumping felt worldwide—land subsidence, impaired water quality, and damaged ecosystems, all against the looming threat of climate change. The state largely entrusts the control of depletion to the local level. This study uses internationally accepted water resources planning theories systematically to investigate three key aspects of controlling groundwater depletion in California, with an emphasis on local-level action: (a) making decisions and engaging stakeholders; (b) monitoring groundwater; and (c) using mandatory, fee-based and voluntary approaches to control groundwater depletion (e.g., pumping restrictions, pumping fees, and education about water conservation, respectively). The methodology used is the social science-derived technique of content analysis, which involves using a coding scheme to record these three elements in local rules and plans, and State legislation, then analyzing patterns and trends. The study finds that Californian local groundwater managers rarely use, or plan to use, mandatory and fee-based measures to control groundwater depletion. Most use only voluntary approaches or infrastructure to attempt to reduce depletion, regardless of whether they have more severe groundwater problems, or problems which are more likely to have irreversible adverse effects. The study suggests legal reforms to the local groundwater planning system, drawing upon its empirical findings. Considering the content of these recommendations may also benefit other jurisdictions that use a local groundwater management planning paradigm.

Microcosm assays and Taguchi experimental design for treatment of oil sludge containing high concentration of hydrocarbons.

PubMed

Castorena-Cortés, G; Roldán-Carrillo, T; Zapata-Peñasco, I; Reyes-Avila, J; Quej-Aké, L; Marín-Cruz, J; Olguín-Lora, P

2009-12-01

Microcosm assays and Taguchi experimental design was used to assess the biodegradation of an oil sludge produced by a gas processing unit. The study showed that the biodegradation of the sludge sample is feasible despite the high level of pollutants and complexity involved in the sludge. The physicochemical and microbiological characterization of the sludge revealed a high concentration of hydrocarbons (334,766+/-7001 mg kg(-1) dry matter, d.m.) containing a variety of compounds between 6 and 73 carbon atoms in their structure, whereas the concentration of Fe was 60,000 mg kg(-1) d.m. and 26,800 mg kg(-1) d.m. of sulfide. A Taguchi L(9) experimental design comprising 4 variables and 3 levels moisture, nitrogen source, surfactant concentration and oxidant agent was performed, proving that moisture and nitrogen source are the major variables that affect CO(2) production and total petroleum hydrocarbons (TPH) degradation. The best experimental treatment yielded a TPH removal of 56,092 mg kg(-1) d.m. The treatment was carried out under the following conditions: 70% moisture, no oxidant agent, 0.5% of surfactant and NH(4)Cl as nitrogen source.

Direct and indirect effects of the fungicide Carbendazim in tropical freshwater microcosms.

PubMed

Daam, Michiel A; Satapornvanit, Kriengkrai; Van den Brink, Paul J; Nogueira, António J A

2010-02-01

Direct and indirect effects of the fungicide carbendazim on ecosystem structure and functioning were studied < or =8 weeks after application (nominal concentrations: 0, 3.3, 33, 100, and 1000 microg/L) to outdoor microcosms in Thailand. Direct effects on macroinvertebrates are discussed in detail in a separate article. The present article presents the effects on other end points and discusses the hypothesized ecologic effect chain. Negative treatment effects on the zooplankton community were only recorded for the highest carbendazim treatment (NOEC(community) = 100 microg/L). The rotifer Keratella tropica, cladocerans (Moina micrura, Ceriodaphnia cornuta, and Diaphanosoma sp.), and cyclopoid copepods were decreased or even eliminated at this treatment level. The decrease in zooplankton and macroinvertebrate abundances was accompanied by an increase in numbers of several tolerant invertebrates, presumably caused by a release from competition and predation. The death of sensitive invertebrates probably also led to an overall decreased grazing pressure because increased levels of chlorophyll-a and bloom of the floating macrophyte Wolffia sp. were noted. The increase in primary producers is discussed to be the probable cause of changes in physicochemical water conditions, eventually resulting in an anoxic water layer during the last 3 weeks of the experiment. This is likely to have resulted in decreased invertebrate abundances noted in that period. Furthermore, the decreased decomposition of Musa (banana) leaves observed 8 weeks after application is considered to be the indirect effect of a decreased microbial activity resulting from these anoxic water conditions, rather than a direct toxic effect of carbendazim.

Influences of aquatic plants on the fate of the pyrethroid insecticide lambda-cyhalothrin in aquatic environments.

PubMed

Hand, L H; Kuet, S F; Lane, M C; Maund, S J; Warinton, J S; Hill, I R

2001-08-01

Aquatic exposure assessments for pesticides are generally based on laboratory studies performed in water alone or water sediment systems. Although aquatic macrophytes, which include a variety of bryophytes, macroalgae, and angiosperms, can be a significant component of many aquatic ecosystems, their impact on pesticide fate is generally not included in exposure assessments. To investigate the influence of aquatic plants on the fate and behavior of the pyrethroid insecticide lambda (lambda)-cyhalothrin, two laboratory experiments (to assess adsorption and degradation) and an indoor microcosm study (to assess fate under semirealistic conditions) were conducted. In the laboratory studies, adsorption to macrophytes was extensive and essentially irreversible, and degradation occurred rapidly by cleavage of the ester bond. In the indoor microcosm, which contained water, sediment, and macrophytes from a pond, degradation was also rapid, with DT50 and DT90 values of less than 3 and 19 h, respectively, for dissipation from the water column and of less than 3 and 56 h, respectively, for the whole system. For adsorptive and readily degraded pesticides like lambda-cyhalothrin, we conclude that macrophytes have considerable influence on fate and behavior in surface waters.

LABORATORY SCALE STEAM INJECTION TREATABILITY STUDIES

EPA Science Inventory

Laboratory scale steam injection treatability studies were first developed at The University of California-Berkeley. A comparable testing facility has been developed at USEPA's Robert S. Kerr Environmental Research Center. Experience has already shown that many volatile organic...

LABORATORY MICROCOSM EXPERIMENTS OF OXIDATION PROCESSES AFTER STEAM INJECTION

EPA Science Inventory

Aggressive thermal methods such as steam injection or resistive heating are known to be effective for the recovery of many types of volatile and semivolatile compounds. It has been suggested that oxidation or other chemical reactions that occur at remediation temperatures can ai...

Thermal adaptation of heterotrophic soil respiration in laboratory microcosms.

Treesearch

Mark A. Bradford; Brian W. Watts; Christian A. Davies

2010-01-01

Respiration of heterotrophic microorganisms decomposing soil organic carbon releases carbon dioxide from soils to the atmosphere. In the short term, soil microbial respiration is strongly dependent on temperature. In the long term, the response of heterotrophic soil respiration to temperature is uncertain. However, following established evolutionary tradeoffs, mass-...

Draft Test Guideline: Site-Specific Aquatic Microcosm Test, Laboratory

EPA Pesticide Factsheets

The following draft test guideline is part of a series of test guidelines that have been developed by EPA for use in the testing of pesticides and toxic substances, and the development of test data for submission to the Agency for review.

[Study of quality of a branch laboratory--an opinion of a laboratory manager].

PubMed

Yazawa, Naoyuki

2006-11-01

At the stage of establishing a branch laboratory, quality evaluation is extremely difficult. Even the results of a control survey by the headquarters of the branch laboratory are unhelpful. For a clinical laboratory, the most important function is to provide reliable data all the time, and to maintain the reliability of clinical doctors with informed responses. We mostly refer to control surveys and daily quality control data to evaluate a clinical laboratory, but we rarely check its fundamental abilities, such as planning events, preserving statistical data about the standard range, using the right method for quality control and others. This is generally disregarded and it is taken for granted that they will be correct the first time. From my six years of experience working with X's branch laboratory, I realized that there might be some relation between the quality of a branch laboratory and the fundamental abilities of the company itself. I would never argue that all branch laboratories are ineffective, but they should be conscious of fundamental activities. The referring laboratory, not the referral laboratory, should be responsible for ensuring that the referral laboratory's examination results and findings are correct.

Laboratory studies in ultraviolet solar physics

NASA Technical Reports Server (NTRS)

Parkinson, W. H.; Kohl, J. L.; Gardner, L. D.; Raymond, J. C.; Smith, P. L.

1991-01-01

The research activity comprised the measurement of basic atomic processes and parameters which relate directly to the interpretation of solar ultraviolet observations and to the development of comprehensive models of the component structures of the solar atmosphere. The research was specifically directed towards providing the relevant atomic data needed to perform and to improve solar diagnostic techniques which probe active and quiet portions of the solar chromosphere, the transition zone, the inner corona, and the solar wind acceleration regions of the extended corona. The accuracy with which the physical conditions in these structures can be determined depends directly on the accuracy and completeness of the atomic and molecular data. These laboratory data are used to support the analysis programs of past and current solar observations (e.g., the Orbiting solar Observatories, the Solar Maximum Mission, the Skylab Apollo Telescope Mount, and the Naval Research Laboratory's rocket-borne High Resolution Telescope and Spectrograph). In addition, we attempted to anticipate the needs of future space-borne solar studies such as from the joint ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft. Our laboratory activities stressed two categories of study: (1) the measurement of absolute rate coefficients for dielectronic recombination and electron impact excitation; and (2) the measurement of atomic transition probabilities for solar density diagnostics. A brief summary of the research activity is provided.

The impact of different proportions of a treated effluent on the biotransformation of selected micro-contaminants in river water microcosms.

PubMed

Nödler, Karsten; Tsakiri, Maria; Licha, Tobias

2014-10-10

Attenuation of micro-contaminants is a very complex field in environmental science and evidence suggests that biodegradation rates of micro-contaminants in the aqueous environment depend on the water matrix. The focus of the study presented here is the systematic comparison of biotransformation rates of caffeine, carbamazepine, metoprolol, paracetamol and valsartan in river water microcosms spiked with different proportions of treated effluent (0%, 0.1%, 1%, and 10%). Biotransformation was identified as the dominating attenuation process by the evolution of biotransformation products such as atenolol acid and valsartan acid. Significantly decreasing biotransformation rates of metoprolol were observed at treated effluent proportions ≥ 0.1% whereas significantly increasing biotransformation rates of caffeine and valsartan were observed in the presence of 10% treated effluent. Potential reasons for the observations are discussed and the addition of adapted microorganisms via the treated effluent was suggested as the most probable reason. The impact of additional phosphorus on the biodegradation rates was tested and the experiments revealed that phosphorus-limitation was not responsible.

The Essential Role for Laboratory Studies in Atmospheric Chemistry.

PubMed

Burkholder, James B; Abbatt, Jonathan P D; Barnes, Ian; Roberts, James M; Melamed, Megan L; Ammann, Markus; Bertram, Allan K; Cappa, Christopher D; Carlton, Annmarie G; Carpenter, Lucy J; Crowley, John N; Dubowski, Yael; George, Christian; Heard, Dwayne E; Herrmann, Hartmut; Keutsch, Frank N; Kroll, Jesse H; McNeill, V Faye; Ng, Nga Lee; Nizkorodov, Sergey A; Orlando, John J; Percival, Carl J; Picquet-Varrault, Bénédicte; Rudich, Yinon; Seakins, Paul W; Surratt, Jason D; Tanimoto, Hiroshi; Thornton, Joel A; Tong, Zhu; Tyndall, Geoffrey S; Wahner, Andreas; Weschler, Charles J; Wilson, Kevin R; Ziemann, Paul J

2017-03-07

Laboratory studies of atmospheric chemistry characterize the nature of atmospherically relevant processes down to the molecular level, providing fundamental information used to assess how human activities drive environmental phenomena such as climate change, urban air pollution, ecosystem health, indoor air quality, and stratospheric ozone depletion. Laboratory studies have a central role in addressing the incomplete fundamental knowledge of atmospheric chemistry. This article highlights the evolving science needs for this community and emphasizes how our knowledge is far from complete, hindering our ability to predict the future state of our atmosphere and to respond to emerging global environmental change issues. Laboratory studies provide rich opportunities to expand our understanding of the atmosphere via collaborative research with the modeling and field measurement communities, and with neighboring disciplines.

Scattering of phytoplankton cells from cytometry during a microcosm experiment

NASA Astrophysics Data System (ADS)

Moutier, W.; Duforêt-Gaurier, L.; Loisel, H.; Thyssen, M.; Mériaux, X.; Desailly, D.; Courcot, L.; Dugenne, M.

2016-02-01

This study presents an application of the CytoSense flow cytometer (CytoBuoy b.v., NL) as a powerful tool to analyze optical properties of phytoplankton cells. Recently, Duforêt et al., (2015) developed a methodology to derive the forward, sideward and backward cross section (σFWS, σSWS and σbb, respectively) of individual particles from the CytoSense. For the first time, this methodology was applied to phytoplankton cultures. A 20 day microcosm experiment was conducted on two phytoplankton species (Chlamydomonas concordia and Thalassiosira pseudonana). We realized daily sampling for biogeochemical and flow cytometer analysis and carried out optical measurements. Scanning electron migrographs (SEM) were performed at different life stages to investigate the cells morphology.First, CytoSense estimates were tested against radiative transfer computations. The comparison exercise, is based on radiative transfer simulations because for phytoplankton cultures, in situ measurements of σFWS and σSWS, particle by particle, are not available in literature. For that purpose, we build a database of 590,000 simulations, considering homogeneous and multi-layered spheres, to represent the optical properties of a large diversity of phytoplankton cells. Comparison showed that the CytoSense estimates for the cultures are consistent with values predicted by the theory. Second, the flow cytometer was used to analyze the temporal course of the forward and the sideward efficiency during the entire life-cycle. Results showed differences between the two species. From an ACP analysis, the variation of the optical properties were associated with the chlorophyll-a concentration by living cell, the thickness of the frustule and the aggregate formation. To finish, the bulk backscattering coefficient was rebuilt from σbb of individual cells and compare with the bb measured by a WET Labs ECO-BB9. Relative errors (RE) were between 0.3 and 0.47 and the mean RE was of 0.36. A such work shows

Nitrification Is a Primary Driver of Nitrous Oxide Production in Laboratory Microcosms from Different Land-Use Soils.

PubMed

Liu, Rui; Hu, Hangwei; Suter, Helen; Hayden, Helen L; He, Jizheng; Mele, Pauline; Chen, Deli

2016-01-01

Most studies on soil N2O emissions have focused either on the quantifying of agricultural N2O fluxes or on the effect of environmental factors on N2O emissions. However, very limited information is available on how land-use will affect N2O production, and nitrifiers involved in N2O emissions in agricultural soil ecosystems. Therefore, this study aimed at evaluating the relative importance of nitrification and denitrification to N2O emissions from different land-use soils and identifying the potential underlying microbial mechanisms. A (15)N-tracing experiment was conducted under controlled laboratory conditions on four agricultural soils collected from different land-use. We measured N2O fluxes, nitrate ([Formula: see text]), and ammonium ([Formula: see text]) concentration and (15)N2O, (15)[Formula: see text], and (15)[Formula: see text] enrichment during the incubation. Quantitative PCR was used to quantify ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). Our results showed that nitrification was the main contributor to N2O production in soils from sugarcane, dairy pasture and cereal cropping systems, while denitrification played a major role in N2O production in the vegetable soil under the experimental conditions. Nitrification contributed to 96.7% of the N2O emissions in sugarcane soil followed by 71.3% in the cereal cropping soil and 70.9% in the dairy pasture soil, while only around 20.0% of N2O was produced from nitrification in vegetable soil. The proportion of nitrified nitrogen as N2O (PN2O-value) varied across different soils, with the highest PN2O-value (0.26‰) found in the cereal cropping soil, which was around 10 times higher than that in other three systems. AOA were the abundant ammonia oxidizers, and were significantly correlated to N2O emitted from nitrification in the sugarcane soil, while AOB were significantly correlated with N2O emitted from nitrification in the cereal cropping soil. Our findings suggested that soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morton, R.D.; Duke, T.W.; Macauley, J.M.

Effects of a used drilling fluid on an experimental seagrass community (Thalassia testudinum) were measured by exposing the community to the suspended particulate phase (SPP) in laboratory microcosms. Structure of the macroinvertebrate assemblage, growth and chlorophyll content of grass and associated epiphytes, and rates of decomposition as indicated by weight loss of grass leaves in treated and untreated microcosms were compared. There were statistically significant differences in community structure and function among untreated microcosms and those receiving the clay and drilling fluid. For example, drilling fluid and clay caused a significant loss in the number of the ten most numericallymore » abundant (dominant) macroinvertebrates, and drilling fluid decreased the rate at which Thalassia leaves decomposed.« less

A qualitative case study of instructional support for web-based simulated laboratory exercises in online college chemistry laboratory courses

NASA Astrophysics Data System (ADS)

Schulman, Kathleen M.

This study fills a gap in the research literature regarding the types of instructional support provided by instructors in online introductory chemistry laboratory courses that employ chemistry simulations as laboratory exercises. It also provides information regarding students' perceptions of the effectiveness of that instructional support. A multiple case study methodology was used to carry out the research. Two online introductory chemistry courses were studied at two community colleges. Data for this study was collected using phone interviews with faculty and student participants, surveys completed by students, and direct observation of the instructional designs of instructional support in the online Blackboard web sites and the chemistry simulations used by the participating institutions. The results indicated that the instructors provided multiple types of instructional support that correlated with forms of effective instructional support identified in the research literature, such as timely detailed feedback, detailed instructions for the laboratory experiments, and consistency in the instructional design of lecture and laboratory course materials, including the chemistry lab simulation environment. The students in one of these courses identified the following as the most effective types of instructional support provided: the instructor's feedback, opportunities to apply chemistry knowledge in the chemistry lab exercises, detailed procedures for the simulated laboratory exercises, the organization of the course Blackboard sites and the chemistry lab simulation web sites, and the textbook homework web sites. Students also identified components of instructional support they felt were missing. These included a desire for more interaction with the instructor, more support for the simulated laboratory exercises from the instructor and the developer of the chemistry simulations, and faster help with questions about the laboratory exercises or experimental

The Essential Role for Laboratory Studies in Atmospheric Chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burkholder, James B.; Abbatt, Jonathan P. D.; Barnes, Ian

Laboratory studies of atmospheric chemistry characterize the nature of atmospherically relevant processes down to the molecular level, providing fundamental information used to assess how human activities drive environmental phenomena such as climate change, urban air pollution, ecosystem health, indoor air quality, and stratospheric ozone depletion. Laboratory studies have a central role in addressing the incomplete fundamental knowledge of atmospheric chemistry. This paper highlights the evolving science needs for this community and emphasizes how our knowledge is far from complete, hindering our ability to predict the future state of our atmosphere and to respond to emerging global environmental change issues. Finally,more » laboratory studies provide rich opportunities to expand our understanding of the atmosphere via collaborative research with the modeling and field measurement communities, and with neighboring disciplines.« less

Laboratory Information Management System (LIMS): A case study

NASA Technical Reports Server (NTRS)

Crandall, Karen S.; Auping, Judith V.; Megargle, Robert G.

1987-01-01

In the late 70's, a refurbishment of the analytical laboratories serving the Materials Division at NASA Lewis Research Center was undertaken. As part of the modernization efforts, a Laboratory Information Management System (LIMS) was to be included. Preliminary studies indicated a custom-designed system as the best choice in order to satisfy all of the requirements. A scaled down version of the original design has been in operation since 1984. The LIMS, a combination of computer hardware, provides the chemical characterization laboratory with an information data base, a report generator, a user interface, and networking capabilities. This paper is an account of the processes involved in designing and implementing that LIMS.

In-situ subaqueous capping of mercury-contaminated sediments in a fresh-water aquatic system, Part I-Bench-scale microcosm study to assess methylmercury production.

PubMed

Randall, Paul M; Fimmen, Ryan; Lal, Vivek; Darlington, Ramona

2013-08-01

Bench-scale microcosm experiments were designed to provide a better understanding of the potential for Hg methylation in sediments from an aquatic environment. Experiments were conducted to examine the function of sulfate concentration, lactate concentration, the presence/absence of an aqueous inorganic Hg spike, and the presence/absence of inoculums of Desulfovibrio desulfuricans, a strain of sulfate-reducing bacteria (SRB) commonly found in the natural sediments of aquatic environments. Incubations were analyzed for both the rate and extent of (methylmercury) MeHg production. Methylation rates were estimated by analyzing MeHg and Hg after 2, 7, 14, 28, and 42 days. The production of metabolic byproducts, including dissolved gases as a proxy for metabolic utilization of carbon substrate, was also monitored. In all treatments amended with lactate, sulfate, Hg, and SRB, MeHg was produced (37ng/g-sediment dry weight) after only 48h of incubation and reached a maximum sediment concentration of 127ng/g-sediment dry weight after the 42 day incubation period. Aqueous phase production of MeHg was observed to be 10ng/L after 2 day, reaching a maximum observed concentration of 32.8ng/L after 14 days, and declining to 10.8ng/L at the end of the incubation period (42 day). The results of this study further demonstrates that, in the presence of an organic carbon substrate, sulfate, and the appropriate consortia of microorganisms, sedimentary Hg will be transformed into MeHg through bacterial metabolism. Further, this study provided the basis for evaluation of an in-situ subaqueous capping strategy that may limit (or potentially enhance) MeHg production. Published by Elsevier Inc.

A Three-Year Feedback Study of a Remote Laboratory Used in Control Engineering Studies

ERIC Educational Resources Information Center

Chevalier, Amélie; Copot, Cosmin; Ionescu, Clara; De Keyser, Robin

2017-01-01

This paper discusses the results of a feedback study for a remote laboratory used in the education of control engineering students. The goal is to show the effectiveness of the remote laboratory on examination results. To provide an overview, the two applications of the remote laboratory are addressed: 1) the Stewart platform, and 2) the quadruple…

Biodegradation of phenanthrene in bioaugmented microcosm by consortium ASP developed from coastal sediment of Alang-Sosiya ship breaking yard.

PubMed

Patel, Vilas; Patel, Janki; Madamwar, Datta

2013-09-15

A phenanthrene-degrading bacterial consortium (ASP) was developed using sediment from the Alang-Sosiya shipbreaking yard at Gujarat, India. 16S rRNA gene-based molecular analyses revealed that the bacterial consortium consisted of six bacterial strains: Bacillus sp. ASP1, Pseudomonas sp. ASP2, Stenotrophomonas maltophilia strain ASP3, Staphylococcus sp. ASP4, Geobacillus sp. ASP5 and Alcaligenes sp. ASP6. The consortium was able to degrade 300 ppm of phenanthrene and 1000 ppm of naphthalene within 120 h and 48 h, respectively. Tween 80 showed a positive effect on phenanthrene degradation. The consortium was able to consume maximum phenanthrene at the rate of 46 mg/h/l and degrade phenanthrene in the presence of other petroleum hydrocarbons. A microcosm study was conducted to test the consortium's bioremediation potential. Phenanthrene degradation increased from 61% to 94% in sediment bioaugmented with the consortium. Simultaneously, bacterial counts and dehydrogenase activities also increased in the bioaugmented sediment. These results suggest that microbial consortium bioaugmentation may be a promising technology for bioremediation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Knowledge Retention for Computer Simulations: A study comparing virtual and hands-on laboratories

NASA Astrophysics Data System (ADS)

Croom, John R., III

The use of virtual laboratories has the potential to change physics education. These low-cost, interactive computer activities interest students, allow for easy setup, and give educators a way to teach laboratory based online classes. This study investigated whether virtual laboratories could replace traditional hands-on laboratories and whether students could retain the same long-term knowledge in virtual laboratories as compared to hands-on laboratories. This study is a quantitative quasi-experiment that used a multiple posttest design to determine if students using virtual laboratories would retain the same knowledge as students who performed hands-on laboratories after 9 weeks. The study was composed of 336 students from 14 school districts. Students had their performances on the laboratories and their retention of the laboratories compared to a series of factors that might have affected their retention using a pretest and two posttests, which were compared using a t test. The results showed no significant difference in short-term learning between the hands-on laboratory groups and virtual laboratory groups. There was, however, a significant difference (p = .005) between the groups in long-term retention; students in the hands-on laboratory groups retained more information than those in the virtual laboratory groups. These results suggest that long-term learning is enhanced when a laboratory contains a hands-on component. Finally, the results showed that both groups of students felt their particular laboratory style was superior to the alternative method. The findings of this study can be used to improve the integration of virtual laboratories into science curriculum.

21 CFR 58.185 - Reporting of nonclinical laboratory study results.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Reporting of nonclinical laboratory study results. 58.185 Section 58.185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Reporting of nonclinical laboratory study results. (a) A final report shall be prepared for each nonclinical...

21 CFR 58.185 - Reporting of nonclinical laboratory study results.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Reporting of nonclinical laboratory study results. 58.185 Section 58.185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Reporting of nonclinical laboratory study results. (a) A final report shall be prepared for each nonclinical...

21 CFR 58.185 - Reporting of nonclinical laboratory study results.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Reporting of nonclinical laboratory study results. 58.185 Section 58.185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Reporting of nonclinical laboratory study results. (a) A final report shall be prepared for each nonclinical...

Removal of diclofenac and sulfamethoxazole from synthetic municipal waste water in microcosm downflow constructed wetlands: Start-up results.

PubMed

Nowrotek, Monika; Sochacki, Adam; Felis, Ewa; Miksch, Korneliusz

2016-01-01

The objectives of this study were to investigate the start-up removal of pharmaceutical compounds diclofenac and sulfamethoxazole in microcosm downflow constructed wetlands and their effect on the performance of the studied constructed wetlands, and also to assess the effect of plants on the removal of these compounds. The experimental system that was used in this 86-day experiment consisted of 24 columns filled up to 70 cm with predominantly sandy material. Four types of columns were used (six replicates) depending on the presence of plants (Phalaris arundinacea L. var. picta L.) and the presence of pharmaceutical compounds in the influent. The influent was synthetic municipal waste water to which a mixture of 5 mg/L of diclofenac and 5 mg/L of sulfamethoxazole was added. The observed removal of diclofenac was moderate (approx. 50%) and the removal of sulfamethoxazole was relatively low (24-30%). It was found that the removal of diclofenac and sulfamethoxazole was not affected by the vegetation. The presence of diclofenac and sulfamethoxazole in the influent had significant effect on the effluent concentration of N-NO3 and the water loss in the columns, which in both cases were lower than in the control columns. The scope for further research was discussed.

Comparison of laboratory single species and field population-level effects of the pyrethroid insecticide lambda-cyhalothrin on freshwater invertebrates.

PubMed

Schroer, A F W; Belgers, J D M; Brock, T C M; Matser, A M; Maund, S J; Van den Brink, P J

2004-04-01

The toxicity of the pyrethroid insecticide lambda-cyhalothrin to freshwater invertebrates has been investigated using data from short-term laboratory toxicity tests and in situ bioassays and population-level effects in field microcosms. In laboratory tests, patterns of toxicity were consistent with previous data on pyrethroids. The midge Chaoborus obscuripes was most sensitive (48- and 96-h EC50 = 2.8 ng/L). Other insect larvae (Hemiptera, Ephemeroptera) and macrocrustacea (Amphipoda, Isopoda) were also relatively sensitive, with 48- and 96-h EC50 values between 10 and 100 ng/L. Generally, microcrustacea (Cladocera, Copepoda) and larvae of certain insect groups (Odonata and Chironomidae) were less sensitive, with 48-h EC50 values higher than 100 ng/L. Mollusca and Plathelminthes were insensitive and were unaffected at concentrations at and above the water solubility (5 microg/L). Generally, the EC50 values based on initial population responses in field enclosures were similar to values derived from laboratory tests with the same taxa. Also, the corresponding fifth and tenth percentile hazard concentrations (HC5 and HC10) were similar (laboratory HC5 = 2.7 ng/L and field HC5 = 4.1 ng/L; laboratory and field HC10 = 5.1 ng/L), at least when based on the same sensitive taxonomic groups (insects and crustaceans) and when a similar concentration range was taken into account. In the three field enclosure experiments and at a treatment level of 10 ng/L, consistent effects were observed for only one population (Chaoborus obscuripes), with recovery taking place within 3 to 6 weeks. The laboratory HC5 (2.7 ng/L) and HC10 (5.1 ng/L) based on acute EC50 values of all aquatic arthropod taxa were both lower than this 10 ng/L, a concentration that might represent the "regulatory acceptable concentration." The HC5 and HC10 values in this study in The Netherlands (based on static laboratory tests with freshwater arthropods) were very similar to those derived from a previous study in

Successful Sampling Strategy Advances Laboratory Studies of NMR Logging in Unconsolidated Aquifers

NASA Astrophysics Data System (ADS)

Behroozmand, Ahmad A.; Knight, Rosemary; Müller-Petke, Mike; Auken, Esben; Barfod, Adrian A. S.; Ferré, Ty P. A.; Vilhelmsen, Troels N.; Johnson, Carole D.; Christiansen, Anders V.

2017-11-01

The nuclear magnetic resonance (NMR) technique has become popular in groundwater studies because it responds directly to the presence and mobility of water in a porous medium. There is a need to conduct laboratory experiments to aid in the development of NMR hydraulic conductivity models, as is typically done in the petroleum industry. However, the challenge has been obtaining high-quality laboratory samples from unconsolidated aquifers. At a study site in Denmark, we employed sonic drilling, which minimizes the disturbance of the surrounding material, and extracted twelve 7.6 cm diameter samples for laboratory measurements. We present a detailed comparison of the acquired laboratory and logging NMR data. The agreement observed between the laboratory and logging data suggests that the methodologies proposed in this study provide good conditions for studying NMR measurements of unconsolidated near-surface aquifers. Finally, we show how laboratory sample size and condition impact the NMR measurements.

Evaluation of TCDD biodegradability under different redox conditions.

PubMed

Kao, C M; Chen, S C; Liu, J K; Wu, M J

2001-09-01

Polychlorinated dibenzo-p-dioxins have been generated as unwanted by-products in many industrial processes. Although their widespread distribution in different environmental compartments has been recognized, little is known about their fate in the ultimate environment sinks. The highly stable dioxin isomer 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been called the most toxic compound known to man. In this laboratory microcosm study, TCDD bioavailability was evaluated under five reduction/oxidation (redox) conditions including aerobic biodegradation, aerobic cometabolism, methanogenesis, iron reduction, and reductive dechlorination. Activated sludge and aquifer sediments from a TCDD and a pentachlorophenol (PCP) contaminated site were used as the inocula. Acetate, sludge cake, and cane molasses were used as the primary substrates (carbon sources) in cometabolism and reductive dechlorination microcosms. After a 90-day incubation period, microcosms constructed under reductive dechlorination conditions were the only treatment showing promising remediation results. The highest TCDD degradation rate [up to 86% of TCDD removal (with an initial concentration of 96 microg/kg of soil)] was observed in the microcosms with anaerobic activated sludge as the microbial inocula and sludge cakes as the primary substrates. Except for reductive dechlorination microcosms, no significant TCDD removal was observed in the microcosms prepared under other conditions. Thus, application of an effective primary substrate to enhance the reductive dechlorination process is a feasible method for TCDD bioremediation. Bioremediation expense can be significantly reduced by the supplement of some less expensive alternative substrates (e.g., sludge cakes, cane molasses). Results would be useful in designing a scale-up in situ or on-site bioremediation system such as bioslurry reactor for field application.

A Science Librarian in the Laboratory: A Case Study

ERIC Educational Resources Information Center

Tomaszewski, Robert

2011-01-01

A science librarian in the laboratory can become a "point of access" for database instruction and provide a learning opportunity for students to develop their information literacy skills. A case study describes how a librarian in an organic chemistry laboratory helps the class run smoothly and identifies the science librarian as an ally and a…

Effect of concentration gradients on biodegradation in bench-scale sand columns with HYDRUS modeling of hydrocarbon transport and degradation.

PubMed

Horel, Agota; Schiewer, Silke; Misra, Debasmita

2015-09-01

The present research investigated to what extent results obtained in small microcosm experiments can be extrapolated to larger settings with non-uniform concentrations. Microbial hydrocarbon degradation in sandy sediments was compared for column experiments versus homogenized microcosms with varying concentrations of diesel, Syntroleum, and fish biodiesel as contaminants. Syntroleum and fish biodiesel had higher degradation rates than diesel fuel. Microcosms showed significantly higher overall hydrocarbon mineralization percentages (p < 0.006) than columns. Oxygen levels and moisture content were likely not responsible for that difference, which could, however, be explained by a strong gradient of fuel and nutrient concentrations through the column. The mineralization percentage in the columns was similar to small-scale microcosms at high fuel concentrations. While absolute hydrocarbon degradation increased, mineralization percentages decreased with increasing fuel concentration which was corroborated by saturation kinetics; the absolute CO2 production reached a steady plateau value at high substrate concentrations. Numerical modeling using HYDRUS 2D/3D simulated the transport and degradation of the investigated fuels in vadose zone conditions similar to those in laboratory column experiments. The numerical model was used to evaluate the impact of different degradation rate constants from microcosm versus column experiments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morton, R.D.; Duke, T.W.; Macauley, J.M.

Effects of a used drilling fluid on an experimental seagrass community (Thalassia testudinum Konig et Sims) were measured by exposing the community to the suspended particulate phase (SPP) in laboratory microcosms. Structure of the macroinvertebrate assemblage, growth, and chlorophyll content of grass and associated epiphytes, and rates of decomposition as indicated by weight loss of grass leaves in treated and untreated microcosms were compared. There were statistically significant differences in community structure and function among untreated microcosms and those receiving the clay and drilling fluid. For example, drilling fluid and clay caused a significant decrease in the numbers of themore » ten most numerically abundant (dominant) macroinvertebrates, and drilling fluid decreased the rate at which Thalassia leaves decomposed.« less

Comparative metagenomic analysis of microcosm structures and lignocellulolytic enzyme systems of symbiotic biomass-degrading consortia.

PubMed

Wongwilaiwalin, Sarunyou; Laothanachareon, Thanaporn; Mhuantong, Wuttichai; Tangphatsornruang, Sithichoke; Eurwilaichitr, Lily; Igarashi, Yasuo; Champreda, Verawat

2013-10-01

Decomposition of lignocelluloses by cooperative microbial actions is an essential process of carbon cycling in nature and provides a basis for biomass conversion to fuels and chemicals in biorefineries. In this study, structurally stable symbiotic aero-tolerant lignocellulose-degrading microbial consortia were obtained from biodiversified microflora present in industrial sugarcane bagasse pile (BGC-1), cow rumen fluid (CRC-1), and pulp mill activated sludge (ASC-1) by successive subcultivation on rice straw under facultative anoxic conditions. Tagged 16S rRNA gene pyrosequencing revealed that all isolated consortia originated from highly diverse environmental microflora shared similar composite phylum profiles comprising mainly Firmicutes, reflecting convergent adaptation of microcosm structures, however, with substantial differences at refined genus level. BGC-1 comprising cellulolytic Clostridium and Acetanaerobacterium in stable coexistence with ligninolytic Ureibacillus showed the highest capability on degradation of agricultural residues and industrial pulp waste with CMCase, xylanase, and β-glucanase activities in the supernatant. Shotgun pyrosequencing of the BGC-1 metagenome indicated a markedly high relative abundance of genes encoding for glycosyl hydrolases, particularly for lignocellulytic enzymes in 26 families. The enzyme system comprised a unique composition of main-chain degrading and side-chain processing hydrolases, dominated by GH2, 3, 5, 9, 10, and 43, reflecting adaptation of enzyme profiles to the specific substrate. Gene mapping showed metabolic potential of BGC-1 for conversion of biomass sugars to various fermentation products of industrial importance. The symbiotic consortium is a promising simplified model for study of multispecies mechanisms on consolidated bioprocessing and a platform for discovering efficient synergistic enzyme systems for biotechnological application.

Changes in Microbial (Bacteria and Archaea) Plankton Community Structure after Artificial Dispersal in Grazer-Free Microcosms

PubMed Central

Karayanni, Hera; Meziti, Alexandra; Spatharis, Sofie; Genitsaris, Savvas; Courties, Claude; Kormas, Konstantinos A.

2017-01-01

Microbes are considered to have a global distribution due to their high dispersal capabilities. However, our knowledge of the way geographically distant microbial communities assemble after dispersal in a new environment is limited. In this study, we examined whether communities would converge because similar taxa would be selected under the same environmental conditions, or would diverge because of initial community composition, after artificial dispersal. To this aim, a microcosm experiment was performed, in which the temporal changes in the composition and diversity of different prokaryoplankton assemblages from three distant geographic coastal areas (Banyuls-sur-Mer in northwest Mediterranean Sea, Pagasitikos Gulf in northeast Mediterranean and Woods Hole, MA, USA in the northwest Atlantic), were studied. Diversity was investigated using amplicon pyrosequencing of the V1–V3 hypervariable regions of the 16S rRNA. The three assemblages were grown separately in particle free and autoclaved Banyuls-sur-mer seawater at 18 °C in the dark. We found that the variability of prokaryoplankton community diversity (expressed as richness, evenness and dominance) as well as the composition were driven by patterns observed in Bacteria. Regarding community composition, similarities were found between treatments at family level. However, at the OTU level microbial communities from the three different original locations diverge rather than converge during incubation. It is suggested that slight differences in the composition of the initial prokaryoplankton communities, resulted in separate clusters the following days even when growth took place under identical abiotic conditions. PMID:28587211

Microbial community dynamics during assays of harbour oil spill bioremediation: a microscale simulation study.

PubMed

Cappello, S; Caruso, G; Zampino, D; Monticelli, L S; Maimone, G; Denaro, R; Tripodo, B; Troussellier, M; Yakimov, M; Giuliano, L

2007-01-01

Microcosm experiments simulating an oil spill event were performed to evaluate the response of the natural microbial community structure of Messina harbour seawater following the accidental load of petroleum. An experimental harbour seawater microcosm, supplemented with nutrients and crude oil, was monitored above 15 days in comparison with unpolluted ones (control microcosms). Bacterial cells were counted with a Live/Dead BacLight viability kit; leucine aminopeptidase, beta-glucosidase, alkaline phosphatase, lipase and esterase enzymes were measured using fluorogenic substrates. The microbial community dynamic was monitored by isolation of total RNA, RT-PCR amplification of 16S rRNA, cloning and sequencing. Oil addition stimulated an increase of the total bacterial abundance, leucine aminopeptidase and phosphatase activity rates, as well as a change in the community structure. This suggested a prompt response of micro-organisms to the load of petroleum hydrocarbons. The present study on the viability, specific composition and metabolic characteristics of the microbial community allows a more precise assessment of oil pollution. Both structural and functional parameters offer interesting perspectives as indicators to monitor changes caused by petroleum hydrocarbons. A better knowledge of microbial structural successions at oil-polluted sites is essential for environmental bioremediation. Data obtained in microcosm studies improve our understanding of natural processes occurring during oil spills.

Niche and neutral processes both shape community structure in parallelized, aerobic, single carbon-source enrichments

DOE Data Explorer

Flynn, Theodore M.; Koval, Jason C.; Greenwald, Stephanie M.; Owens, Sarah M.; Kemner, Kenneth M.; Antonopoulos, Dionysios A.

2017-01-01

We present DNA sequence data in FASTA-formatted files from aerobic environmental microcosms inoculated with a sole carbon source. DNA sequences are of 16S rRNA genes present in DNA extracted from each microcosm along with the environmental samples (soil, water) used to inoculate them. These samples were sequenced using the Illumina MiSeq platform at the Environmental Sample Preparation and Sequencing Facility at Argonne National Laboratory. This data is compatible with standard microbiome analysis pipelines (e.g., QIIME, mothur, etc.).

Effects of lambda-cyhalothrin in two ditch microcosm systems of different trophic status.

PubMed

Roessink, Ivo; Arts, Gertie H P; Belgers, J Dick M; Bransen, Fred; Maund, Steve J; Brock, Theo C M

2005-07-01

The fate and effects of the pyrethroid insecticide lambda-cyhalothrin were compared in mesotrophic (macrophyte-dominated) and eutrophic (phytoplankton-dominated) ditch microcosms (approximately 0.5 m3). Lambda-cyhalothrin was applied three times at one-week intervals at concentrations of 10, 25, 50, 100, and 250 ng/L. The rate of dissipation of lambda-cyhalothrin in the water column of the two types of test systems was similar. After 1 d, only 30% of the amount applied remained in the water phase. Initial, direct effects were observed primarily on arthropod taxa. The most sensitive species was the phantom midge (Chaoborus obscuripes). Threshold levels for slight and transient direct toxic effects were similar (10 ng/L) between types of test systems. At treatment levels of 25 ng/L and higher, apparent population and community responses occurred. At treatments of 100 and 250 ng/L, the rate of recovery of the macroinvertebrate community was lower in the macrophyte-dominated systems, primarily because of a prolonged decline of the amphipod Gammarus pulex. This species occurred at high densities only in the macrophyte-dominated enclosures. Indirect effects (e.g., increase of rotifers and microcrustaceans) were more pronounced in the plankton-dominated test systems, particularly at treatment levels of 25 ng/L and higher.

Changes in Arctic and Antarctic Sea Ice as a Microcosm of Global Climate Change

NASA Technical Reports Server (NTRS)

Parkinson, Claire L.

2014-01-01

Polar sea ice is a key element of the climate system and has now been monitored through satellite observations for over three and a half decades. The satellite observations reveal considerable information about polar ice and its changes since the late 1970s, including a prominent downward trend in Arctic sea ice coverage and a much lesser upward trend in Antarctic sea ice coverage, illustrative of the important fact that climate change entails spatial contrasts. The decreasing ice coverage in the Arctic corresponds well with contemporaneous Arctic warming and exhibits particularly large decreases in the summers of 2007 and 2012, influenced by both preconditioning and atmospheric conditions. The increasing ice coverage in the Antarctic is not as readily explained, but spatial differences in the Antarctic trends suggest a possible connection with atmospheric circulation changes that have perhaps been influenced by the Antarctic ozone hole. The changes in the polar ice covers and the issues surrounding those changes have many commonalities with broader climate changes and their surrounding issues, allowing the sea ice changes to be viewed in some important ways as a microcosm of global climate change.

Zero-gravity cloud physics laboratory: Candidate experiments definition and preliminary concept studies

NASA Technical Reports Server (NTRS)

Eaton, L. R.; Greco, R. V.; Hollinden, A. B.

1973-01-01

The candidate definition studies on the zero-g cloud physics laboratory are covered. This laboratory will be an independent self-contained shuttle sortie payload. Several critical technology areas have been identified and studied to assure proper consideration in terms of engineering requirements for the final design. Areas include chambers, gas and particle generators, environmental controls, motion controls, change controls, observational techniques, and composition controls. This unique laboratory will allow studies to be performed without mechanical, aerodynamics, electrical, or other type techniques to support the object under study. This report also covers the candidate experiment definitions, chambers and experiment classes, laboratory concepts and plans, special supporting studies, early flight opportunities and payload planning data for overall shuttle payload requirements assessments.

Adaptive radiation of Pseudomonas fluorescens SBW25 in experimental microcosms provides an understanding of the evolutionary ecology and molecular biology of A-L interface biofilm formation.

PubMed

Koza, Anna; Kusmierska, Anna; McLaughlin, Kimberley; Moshynets, Olena; Spiers, Andrew J

2017-07-03

Combined experimental evolutionary and molecular biology approaches have been used to investigate the adaptive radiation of Pseudomonas fluorescens SBW25 in static microcosms leading to the colonisation of the air-liquid interface by biofilm-forming mutants such as the Wrinkly Spreader (WS). In these microcosms, the ecosystem engineering of the early wild-type colonists establishes the niche space for subsequent WS evolution and colonisation. Random WS mutations occurring in the developing population that deregulate diguanylate cyclases and c-di-GMP homeostasis result in cellulose-based biofilms at the air-liquid interface. These structures allow Wrinkly Spreaders to intercept O2 diffusing into the liquid column and limit the growth of competitors lower down. As the biofilm matures, competition increasingly occurs between WS lineages, and niche divergence within the biofilm may support further diversification before system failure when the structure finally sinks. A combination of pleiotropic and epistasis effects, as well as secondary mutations, may explain variations in WS phenotype and fitness. Understanding how mutations subvert regulatory networks to express intrinsic genome potential and key innovations providing a selective advantage in novel environments is key to understanding the versatility of bacteria, and how selection and ecological opportunity can rapidly lead to substantive changes in phenotype and in community structure and function. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Laboratory Studies of Interstellar PAH Analogs

NASA Technical Reports Server (NTRS)

Salama, Farid; DeVincenzi, Donald (Technical Monitor)

2000-01-01

Polycyclic aromatic hydrocarbons (PAHs) are now considered to be an important and ubiquitous component of the organic material in space. PAHs are found in a large variety of extraterrestrial materials such as interplanetary dust particles (IDPs) and meteoritic materials. PAHs are also good candidates to account for the infrared emission bands (UIRs) and the diffuse interstellar optical absorption bands (DIBs) detected in various regions of the interstellar medium. The recent observations made with the Infrared Space Observatory (ISO) have confirmed the ubiquitous nature of the UIR bands and their carriers. PAHs are though to form through chemical reactions in the outflow from carbon-rich stars in a process similar to soot formation. Once injected in the interstellar medium, PAHs are further processed by the interstellar radiation field, interstellar shocks and energetic particles. A major, dedicated, laboratory effort has been undertaken over the past years to measure the physical and chemical characteristics of these complex molecules and their ions under experimental conditions that mimic the interstellar conditions. These measurements require collision-free conditions where the molecules and ions are cold and chemically isolated. The spectroscopy of PAHs under controlled conditions represents an essential diagnostic tool to study the evolution of extraterrestrial PAHs. The Astrochemistry Laboratory program will be discussed through its multiple aspects: objectives, approach and techniques adopted, adaptability to the nature of the problem(s), results and implications for astronomy as well as for molecular spectroscopy. A review of the data generated through laboratory simulations of space environments and the role these data have played in our current understanding of the properties of interstellar PAHs will be presented. The discussion will also introduce the newest generation of laboratory experiments that are currently being developed in order to provide a

Analysis of Factors Influencing PM2.5 in Beijing: A Microcosmic and Dynamic Perspective for Sustainable Development

NASA Astrophysics Data System (ADS)

Wang, Yani; Wang, Jun; Tao, Guiping

2017-12-01

Haze pollution has become a hot issue concerned with the process of modernization and one serious problem requiring urgent solution, especially in Beijing. PM2.5 is the main reason causing haze and its harm. Although there has been research centering on factors affecting PM2.5, little attention has been devoted to the microcosmic and dynamic effects on it. Vector auto-regression (VAR) mode is applied in this study to explore the interaction between PM2.5, PM10, SO2, CO and NO2. Results of Granger causality tests tell that there exists causal relationship between PM10, SO2, CO, NO2 and PM2.5. Impulse response functions (IRFs) show that the response of PM2.5 to a shock in CO is positive and large in the short period, while the reaction of PM2.5 to a shock in SO2 increases over time. Meanwhile, variance decomposition indicate that PM2.5 is more closely related to CO in the short term while SO2’ influence accounts for a higher proportion in the long run. The findings provide a novel perspective to analyze the factors influencing PM2.5 dynamically and contribute to a better understanding of haze and its relationship with sustainable development.

Laboratory and 3-D-distinct element analysis of failure mechanism of slope under external surcharge

NASA Astrophysics Data System (ADS)

Li, N.; Cheng, Y. M.

2014-09-01

Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed post-failure conditions of the slopes have not been considered in sufficient details. There are however increasing interest on the consequences after the initiation of failure which includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more details and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanism and the post-failure mechanism of slope will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure which can give additional information not available from the classical methods of analysis.

EPA worst case water microcosms for testing phage biocontrol of Salmonella.

PubMed

McLaughlin, Michael R; Brooks, John P

2008-01-01

A microplate method was developed as a tool to test phages for their ability to control Salmonella in aqueous environments. The method used EPA (U.S. Environmental Protection Agency) worst case water (WCW) in 96-well plates. The WCW provided a consistent and relatively simple defined turbid aqueous matrix, high in total organic carbon (TOC) and total dissolved salts (TDS), to simulate swine lagoon effluent, without the inconvenience of malodor and confounding effects from other biological factors. The WCW was originally defined to simulate high turbidity and organic matter in water for testing point-of-use filtration devices. Use of WCW to simulate lagoon effluent for phage testing is a new and innovative application of this matrix. Control of physical and chemical parameters (TOC, TDS, turbidity, temperature, and pH) allowed precise evaluation of microbiological parameters (Salmonella and phages). In a typical application, wells containing WCW were loaded with Salmonella enterica susp. enterica serovar Typhimurium (ATCC14028) and treated with phages alone and in cocktail combinations. Mean Salmonella inactivation rates (k, where the lower the value, the greater the inactivation) of phage treatments ranged from -0.32 to -1.60 versus -0.004 for Salmonella controls. Mean log(10) reductions (the lower the value, the greater the reduction) of Salmonella phage treatments were -1.60 for phage PR04-1, -2.14 for phage PR37-96, and -2.14 for both phages in a sequential cocktail, versus -0.08 for Salmonella controls. The WCW microcosm system was an effective tool for evaluating the biocontrol potential of Salmonella phages.

Ammonia oxidation-dependent growth of group I.1b Thaumarchaeota in acidic red soil microcosms.

PubMed

Wu, Yucheng; Conrad, Ralf

2014-07-01

Accumulating evidence suggests that Thaumarchaeota may control nitrification in acidic soils. However, the composition of the thaumarchaeotal communities and their functioning is not well known. Therefore, we studied nitrification activity in relation to abundance and composition of Thaumarchaeota in an acidic red soil from China, using microcosms incubated with and without cellulose amendment. Cellulose was selected to simulate the input of crop residues used to increase soil fertility by local farming. Accumulation of NO3-(-N) was correlated with the growth of Thaumarchaeota as determined by qPCR of 16S rRNA and ammonia monooxygenase (amoA) genes. Both nitrification activity and thaumarchaeotal growth were inhibited by acetylene. They were also inhibited by cellulose amendment, possibly due to the depletion of ammonium by enhanced heterotrophic assimilation. These results indicated that growth of Thaumarchaeota was dependent on ammonia oxidation. The thaumarchaeotal 16S rRNA gene sequences in the red soil were dominated by a clade related to soil fosmid clone 29i4 within the group I.1b, which is widely distributed but so far uncultured. The archaeal amoA sequences were mainly related to the Nitrososphaera sister cluster. These observations suggest that fosmid clone 29i4 and Nitrososphaera sister cluster represent the same group of Thaumarchaeota and dominate ammonia oxidation in acidic red soil. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Laboratory-based versus non-laboratory-based method for assessment of cardiovascular disease risk: the NHANES I Follow-up Study cohort

PubMed Central

Gaziano, Thomas A; Young, Cynthia R; Fitzmaurice, Garrett; Atwood, Sidney; Gaziano, J Michael

2008-01-01

Summary Background Around 80% of all cardiovascular deaths occur in developing countries. Assessment of those patients at high risk is an important strategy for prevention. Since developing countries have limited resources for prevention strategies that require laboratory testing, we assessed if a risk prediction method that did not require any laboratory tests could be as accurate as one requiring laboratory information. Methods The National Health and Nutrition Examination Survey (NHANES) was a prospective cohort study of 14 407 US participants aged between 25–74 years at the time they were first examined (between 1971 and 1975). Our follow-up study population included participants with complete information on these surveys who did not report a history of cardiovascular disease (myocardial infarction, heart failure, stroke, angina) or cancer, yielding an analysis dataset N=6186. We compared how well either method could predict first-time fatal and non-fatal cardiovascular disease events in this cohort. For the laboratory-based model, which required blood testing, we used standard risk factors to assess risk of cardiovascular disease: age, systolic blood pressure, smoking status, total cholesterol, reported diabetes status, and current treatment for hypertension. For the non-laboratory-based model, we substituted body-mass index for cholesterol. Findings In the cohort of 6186, there were 1529 first-time cardiovascular events and 578 (38%) deaths due to cardiovascular disease over 21 years. In women, the laboratory-based model was useful for predicting events, with a c statistic of 0·829. The c statistic of the non-laboratory-based model was 0·831. In men, the results were similar (0·784 for the laboratory-based model and 0·783 for the non-laboratory-based model). Results were similar between the laboratory-based and non-laboratory-based models in both men and women when restricted to fatal events only. Interpretation A method that uses non-laboratory

Intrinsic bioremediation of MTBE-contaminated groundwater at a petroleum-hydrocarbon spill site

NASA Astrophysics Data System (ADS)

Chen, K. F.; Kao, C. M.; Chen, T. Y.; Weng, C. H.; Tsai, C. T.

2006-06-01

An oil-refining plant site located in southern Taiwan has been identified as a petroleum-hydrocarbon [mainly methyl tert-butyl ether (MTBE) and benzene, toluene, ethylbenzene, and xylenes (BTEX)] spill site. In this study, groundwater samples collected from the site were analyzed to assess the occurrence of intrinsic MTBE biodegradation. Microcosm experiments were conducted to evaluate the feasibility of biodegrading MTBE by indigenous microorganisms under aerobic, cometabolic, iron reducing, and methanogenic conditions. Results from the field investigation and microbial enumeration indicate that the intrinsic biodegradation of MTBE and BTEX is occurring and causing the decrease in MTBE and BTEX concentrations. Microcosm results show that the indigenous microorganisms were able to biodegrade MTBE under aerobic conditions using MTBE as the sole primary substrate. The detected biodegradation byproduct, tri-butyl alcohol (TBA), can also be biodegraded by the indigenous microorganisms. In addition, microcosms with site groundwater as the medium solution show higher MTBE biodegradation rate. This indicates that the site groundwater might contain some trace minerals or organics, which could enhance the MTBE biodegradation. Results show that the addition of BTEX at low levels could also enhance the MTBE removal. No MTBE removal was detected in iron reducing and methanogenic microcosms. This might be due to the effects of low dissolved oxygen (approximately 0.3 mg/L) within the plume. The low iron reducers and methanogens (<1.8×103 cell/g of soil) observed in the aquifer also indicate that the iron reduction and methanogenesis are not the dominant biodegradation patterns in the contaminant plume. Results from the microcosm study reveal that preliminary laboratory study is required to determine the appropriate substrates and oxidation-reduction conditions to enhance the biodegradation of MTBE. Results suggest that in situ or on-site aerobic bioremediation using indigenous

Variability of creatinine measurements in clinical laboratories: results from the CRIC study.

PubMed

Joffe, Marshall; Hsu, Chi-yuan; Feldman, Harold I; Weir, Matthew; Landis, J R; Hamm, L Lee

2010-01-01

Estimating equations using serum creatinine (SCr) are often used to assess glomerular filtration rate (GFR). Such creatinine (Cr)-based formulae may produce biased estimates of GFR when using Cr measurements that have not been calibrated to reference laboratories. In this paper, we sought to examine the degree of this variation in Cr assays in several laboratories associated with academic medical centers affiliated with the Chronic Renal Insufficiency Cohort (CRIC) Study; to consider how best to correct for this variation, and to quantify the impact of such corrections on eligibility for participation in CRIC. Variability of Cr is of particular concern in the conduct of CRIC, a large multicenter study of subjects with chronic renal disease, because eligibility for the study depends on Cr-based assessment of GFR. A library of 5 large volume plasma specimens from apheresis patients was assembled, representing levels of plasma Cr from 0.8 to 2.4 mg/dl. Samples from this library were used for measurement of Cr at each of the 14 CRIC laboratories repetitively over time. We used graphical displays and linear regression methods to examine the variability in Cr, and used linear regression to develop calibration equations. We also examined the impact of the various calibration equations on the proportion of subjects screened as potential participants who were actually eligible for the study. There was substantial variability in Cr assays across laboratories and over time. We developed calibration equations for each laboratory; these equations varied substantially among laboratories and somewhat over time in some laboratories. The laboratory site contributed the most to variability (51% of the variance unexplained by the specimen) and variation with time accounted for another 15%. In some laboratories, calibration equations resulted in differences in eligibility for CRIC of as much as 20%. The substantial variability in SCr assays across laboratories necessitates calibration

Effect of phytoplankton on Escherichia coli survival in laboratory microcosms

USDA-ARS?s Scientific Manuscript database

Fecal contamination of water sources is an important water quality issue for agricultural irrigation ponds. Escherichia coli is a common microbial indicator used to evaluate recreational and irrigation water quality. Nuisance algae commonly grow in low- or no-flow irrigation water source The objecti...

Going GLP: Conducting Toxicology Studies in Compliance with Good Laboratory Practices.

PubMed

Carroll, Erica Eggers

2016-01-01

Good laboratory practice standards are US federal regulations enacted as part of the Federal Insecticide, Fungicide, and Rodenticide Act (40 CFR Part 160), the Toxic Substance Control Act (40 CFR Part 792), and the Good Laboratory Practice for Nonclinical Laboratory Studies (21 CFR Part 58) to support protection of public health in the areas of pesticides, chemicals, and drug investigations in response to allegations of inaccurate data acquisition. Essentially, good laboratory practices (GLPs) are a system of management controls for nonclinical research studies involving animals to ensure the uniformity, consistency, reliability, reproducibility, quality, and integrity of data collected as part of chemical (including pharmaceuticals) tests, from in vitro through acute to chronic toxicity tests. The GLPs were established in the United States in 1978 as a result of the Industrial Bio-Test Laboratory scandal which led to congressional hearings and actions to prevent fraudulent data reporting and collection. Although the establishment of infrastructure for GLPs compliance is labor-intensive and time-consuming, achievement and maintenance of GLP compliance ensures the accuracy of the data collected from each study, which is critical for defending results, advancing science, and protecting human and animal health. This article describes how and why those in the US Army Medical Department responsible for protecting the public health of US Army and other military personnel made the policy decision to have its toxicology laboratory achieve complete compliance with GLP standards, the first such among US Army laboratories. The challenges faced and how they were overcome are detailed.

Field and lab conditions alter microbial enzyme and biomass dynamics driving decomposition of the same leaf litter

PubMed Central

Rinkes, Zachary L.; Sinsabaugh, Robert L.; Moorhead, Daryl L.; Grandy, A. Stuart; Weintraub, Michael N.

2013-01-01

Fluctuations in climate and edaphic factors influence field decomposition rates and preclude a complete understanding of how microbial communities respond to plant litter quality. In contrast, laboratory microcosms isolate the intrinsic effects of litter chemistry and microbial community from extrinsic effects of environmental variation. Used together, these paired approaches provide mechanistic insights to decomposition processes. In order to elucidate the microbial mechanisms underlying how environmental conditions alter the trajectory of decay, we characterized microbial biomass, respiration, enzyme activities, and nutrient dynamics during early (<10% mass loss), mid- (10–40% mass loss), and late (>40% mass loss) decay in parallel field and laboratory litter bag incubations for deciduous tree litters with varying recalcitrance (dogwood < maple < maple-oak mixture < oak). In the field, mass loss was minimal (<10%) over the first 50 days (January–February), even for labile litter types, despite above-freezing soil temperatures and adequate moisture during these winter months. In contrast, microcosms displayed high C mineralization rates in the first week. During mid-decay, the labile dogwood and maple litters in the field had higher mass loss per unit enzyme activity than the lab, possibly due to leaching of soluble compounds. Microbial biomass to litter mass (B:C) ratios peaked in the field during late decay, but B:C ratios declined between mid- and late decay in the lab. Thus, microbial biomass did not have a consistent relationship with litter quality between studies. Higher oxidative enzyme activities in oak litters in the field, and higher nitrogen (N) accumulation in the lab microcosms occurred in late decay. We speculate that elevated N suppressed fungal activity and/or biomass in microcosms. Our results suggest that differences in microbial biomass and enzyme dynamics alter the decay trajectory of the same leaf litter under field and lab conditions

Semiconductor laser joint study program with Rome Laboratory

NASA Astrophysics Data System (ADS)

Schaff, William J.; Okeefe, Sean S.; Eastman, Lester F.

1994-09-01

A program to jointly study vertical-cavity surface emitting lasers (VCSEL) for high speed vertical optical interconnects (VOI) has been conducted under an ES&E between Rome Laboratory and Cornell University. Lasers were designed, grown, and fabricated at Cornell University. A VCSEL measurement laboratory has been designed, built, and utilized at Rome Laboratory. High quality VCSEL material was grown and characterized by fabricating conventional lateral cavity lasers that emitted at the design wavelength of 1.04 microns. The VCSEL's emit at 1.06 microns. Threshold currents of 16 mA at 4.8 volts were obtained for 30 microns diameter devices. Output powers of 5 mW were measured. This is 500 times higher power than from the light emitting diodes employed previously for vertical optical interconnects. A new form of compositional grading using a cosinusoidal function has been developed and is very successful for reducing diode series resistance for high speed interconnection applications. A flip-chip diamond package compatible with high speed operation of 16 VCSEL elements has been designed and characterized. A flip-chip device binding effort at Rome Laboratory was also designed and initiated. This report presents details of the one-year effort, including process recipes and results.

An Exploratory Study of Objective Attainment in the Divergent Physics Laboratory.

ERIC Educational Resources Information Center

Lerch, Robert Donald

Students enrolled in the introductory physics laboratory at New Mexico State University participated in this study. A stated set of objectives, developed by Dr. John M. Fowler of the Commission on College Physics, was used in the laboratory. This study attempted to measure student achievement based on the use of these objectives as opposed to the…

Biodegradation of trichloroethylene and its anaerobic daughter products in freshwater wetland sediments

USGS Publications Warehouse

Lorah, M.M.; Olsen, L.D.

2001-01-01

Laboratory microcosms were prepared under methanogenic, sulfate-reducing, and aerobic conditions using sediment and groundwater from a freshwater wetland that is a discharge area for a trichloroethylene (TCE) to evaluate potential biodegradation rates of TCE and its anaerobic daughter products (cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, and vinyl chloride (VC)). Anaerobic degradation of TCE was about an order of magnitude faster under methanogenic conditions than under sulfate-reducing conditions. Both 12DCE and VC were found under sulfate-reducing conditions in the microcosms containing the wetland sediment, but their production, especially for VC, was substantially slower than under methanogenic conditions. Methane concentrations remained approximately constant (when losses in the formalin-amended controls are considered) in the microcosms amended with TCE and increased in the microcosms amended with the 12DCE isomers and VC during the first 18-25 days of incubation. The most rapid decrease in concentrations of TCE, cis-12DCE, trans-12DCE, and VC was found after aerobic methane-oxidizing conditions were definitely established.

High Pb concentration stress on Typha latifolia growth and Pb removal in microcosm wetlands.

PubMed

Han, Jianqiu; Chen, Fengzhen; Zhou, Yumei; Wang, Chaohua

2015-01-01

When constructed wetlands are used to treat high-Pb wastewater, Pb may become a stress to wetland plants, which subsequently reduces treatment performance and the other ecosystem services. To facilitate the design and operation of constructed wetlands for treatment of Pb-rich wastewater, we investigated the irreversible inhibitory level of Pb for Typha latifolia through experiments in microcosm wetlands. Seven horizontal subsurface flow constructed wetlands were built with rectangular plastic tanks and packed with marble chips and sand. All wetlands were transplanted with nine stems of Typha latifolia each. The wetlands were batch operated in a greenhouse with artificial wastewater (10 L each) for 12 days. Influent to the seven wetlands had different concentrations of Pb: 0 mg/L, 10 mg/L, 25 mg/L, 50 mg/L, 100 mg/L, 200 mg/L, and 500 mg/L, respectively. The results suggested that leaf chlorophyll relative content, relative growth rate, photosynthetic characteristics, activities of superoxide dismutase, peroxidase, and content of malondialdehyde were not affected when initial Pb concentration was at 100 mg/L and below. But when initial Pb concentration was above 100 mg/L, all of them were seriously affected. We conclude that high Pb concentrations wastewater could inhibit the growth of Typha latifolia and decrease the removal rate of wetlands.

Frontiers of the food-energy-water trilemma: Sri Lanka as a microcosm of tradeoffs

NASA Astrophysics Data System (ADS)

Perrone, Debra; Hornberger, George

2016-01-01

Food, energy, and water are three critical resources for humanity. As climate variability, population growth, and lifestyle changes amplify the stress placed on each of the resources, the interrelationships among food, energy, and water systems become more pronounced. Political conflict, social and cultural norms, and spatial and temporal distribution of the resources add additional layers of complexity. It is in this context that the significance of understanding the impacts of water scarcity on the decisions around food and energy productions has emerged. Our work establishes tradeoff frontiers (TFs) as a method useful in illustrating the system-level tradeoffs between allocating water for food and water for energy. This paper illustrates how TFs can be used to (1) show how scarcity in water resources affects the tradeoffs between food and energy and (2) explore the political and social constraints that can move production away from what is feasible technically. We use Sri Lanka, a country where water resources are variable both in space and time and a country with relatively self-contained energy and agricultural sectors, as a microcosm of the food security, energy security, and water security trilemma. Nevertheless, our application of tradeoff frontiers is applicable widely to other systems.

Competitive outcome of Daphnia-Simocephalus experimental microcosms: salinity versus priority effects.

PubMed

Loureiro, Cláudia; Pereira, Joana L; Pedrosa, M Arminda; Gonçalves, Fernando; Castro, Bruno B

2013-01-01

Competition is a major driving force in freshwaters, especially given the cyclic nature and dynamics of pelagic food webs. Competition is especially important in the initial species assortment during colonization and re-colonization events, which depends strongly on the environmental context. Subtle changes, such as saline intrusion, may disrupt competitive relationships and, thus, influence community composition. Bearing this in mind, our objective was to assess whether low salinity levels (using NaCl as a proxy) alter the competitive outcome (measured as the rate of population biomass increase) of Daphnia-Simocephalus experimental microcosms, taking into account interactions with priority effects (sequential species arrival order). With this approach, we aimed to experimentally demonstrate a putative mechanism of differential species sorting in brackish environments or in freshwaters facing secondary salinization. Experiments considered three salinity levels, regarding NaCl added (0.00, 0.75 and 1.50 g L(-1)), crossed with three competition scenarios (no priority, priority of Daphnia over Simocephalus, and vice-versa). At lower NaCl concentrations (0.00 and 0.75 g L(-1)), Daphnia was a significantly superior competitor, irrespective of the species inoculation order, suggesting negligible priority effects. However, the strong decrease in Daphnia population growth at 1.50 g L(-1) alleviated the competitive pressure on Simocephalus, causing an inversion of the competitive outcome in favour of Simocephalus. The intensity of this inversion depended on the competition scenario. This salinity-mediated disruption of the competitive outcome demonstrates that subtle environmental changes produce indirect effects in key ecological mechanisms, thus altering community composition, which may lead to serious implications in terms of ecosystem functioning (e.g. lake regime shifts due to reduced grazing) and biodiversity.

OPTIMIZING BTEX BIODEGRADATION UNDER DENITRIFYING CONDITIONS

EPA Science Inventory

Laboratory tests were conducted to determine optimum conditions for benzene, toluene, ethylbenzene, and xylene (collectively known as BTEX) biodegradation by aquifer microorganisms under denitrifying conditions. Microcosms, constructed with aquifer samples from Traverse City, Mic...

Staffing benchmarks for clinical laboratories: a College of American Pathologists Q-Probes study of laboratory staffing at 98 institutions.

PubMed

Jones, Bruce A; Darcy, Teresa; Souers, Rhona J; Meier, Frederick A

2012-02-01

Publicly available information concerning laboratory staffing benchmarks is scarce. One of the few publications on this topic summarized the findings of a Q-Probes study performed in 2004. This publication reports a similar survey with data collected in 2010. To assess the relationship between staffing levels in specified laboratory sections and test volumes in these sections and quantify management span of control. The study defined 4 laboratory sections: anatomic pathology (including cytology), chemistry/hematology/immunology, microbiology, and transfusion medicine. It divided staff into 3 categories: management, nonmanagement (operational or bench staff), and doctoral (MD, PhD) supervisory staff. People in these categories were tabulated as full-time equivalents and exclusions specified. Tests were counted in uniform formats, specified for each laboratory section, according to Medicare rules for the bundling and unbundling of tests. Ninety-eight participating institutions provided data that showed significant associations between test volumes and staffing for all 4 sections. There was wide variation in productivity based on volume. There was no relationship between testing volume per laboratory section and management span of control. Higher productivity in chemistry/hematology/immunology was associated with a higher fraction of tests coming from nonacute care patients. In both the 2004 and 2010 studies, productivity was inseparably linked to test volume. Higher test volume was associated with higher productivity ratios in chemistry/hematology/immunology and transfusion medicine sections. The impact of various testing services on productivity is section-specific.

Effects of a physico-chemical treatment of a dredged sediment on its ecotoxicity after discharge in laboratory gravel pit microcosms.

PubMed

Clément, Bernard; Vaille, Gilles; Moretto, Robert; Vernus, Emmanuel; Abdelghafour, Mohammed

2010-03-15

In France, dredged sediments may be dumped into submerged gravel pits. As a consequence, adverse effects may be expected. In addition, groundwater quality may be impacted due to hydraulic communications with gravel pits. The immersion of dredged sediments into gravel pits should thus be restricted to clean or slightly contaminated sediments to minimize the impacts on aquatic ecosystems and human safe. For highly contaminated sediments, alternatives may be treatments aiming at removing or/and neutralizing contaminants. The Novosol treatment was aimed at neutralizing metals by complexation with orthophosphoric acid and discarding organic pollutants by calcination. The efficiency of the Novosol treatment was assessed in a scenario of sediment immersion into experimental laboratory gravel pits (LGP). A 180L water compartment was set up in each system so as to simulate the gravel pit, and various living organisms were introduced. Following a period of colonization and stabilization, raw and treated sediments were introduced into two different LGPs, and the fate and effects of pollutants were studied during the period of deposition and post-deposition. The treatment had positive effects on survival and development of benthic populations and reproduction of pond snails but the introduction of the treated sediment was followed by an increase in salinity (phosphates, sulphates) and a peak of hexavalent chromium at concentrations above drinkability limits and likely to have impaired invertebrate populations of the water column. The results of this study suggest that discharge of contaminated sediments at a high solid:liquid ratio (1:10) in gravel pits or equivalent aquatic ecosystems may have only limited effects on biota and ground water quality. The Novosol treatment should, however, be improved so as to increase efficiency of oxidised chromium complexation during the phosphatation step. (c) 2009 Elsevier B.V. All rights reserved.

Laboratory and 3-D distinct element analysis of the failure mechanism of a slope under external surcharge

NASA Astrophysics Data System (ADS)

Li, N.; Cheng, Y. M.

2015-01-01

Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed post-failure conditions of the slopes have not been considered in sufficient detail. There is however increasing interest in the consequences after the initiation of failure that includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more detail and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and a laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanisms and the post-failure mechanisms of slopes will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure, which can give additional information not available from the classical methods of analysis.

A Community of Congruence among Secondary Social Studies Teachers: A Case Study

ERIC Educational Resources Information Center

Province, Rachael

2012-01-01

The purpose of this case study was to explore the community of one purposely selected department of secondary social studies teachers. I aimed to provide insight into the nature of one community of congruence amid the many constraints and systemic pressures in school systems today. Many have suggested that education is a microcosm of larger…

Effects of non-steroidal anti-inflammatory drugs on cyanobacteria and algae in laboratory strains and in natural algal assemblages.

PubMed

Bácsi, István; B-Béres, Viktória; Kókai, Zsuzsanna; Gonda, Sándor; Novák, Zoltán; Nagy, Sándor Alex; Vasas, Gábor

2016-05-01

In recent years measurable concentrations of non-steroidal anti-inflammatory drugs (NSAIDs) have been shown in the aquatic environment as a result of increasing human consumption. Effects of five frequently used non-steroidal anti-inflammatory drugs (diclofenac, diflunisal, ibuprofen, mefenamic acid and piroxicam in 0.1 mg ml(-1) concentration) in batch cultures of cyanobacteria (Synechococcus elongatus, Microcystis aeruginosa, Cylindrospermopsis raciborskii), and eukaryotic algae (Desmodesmus communis, Haematococcus pluvialis, Cryptomonas ovata) were studied. Furthermore, the effects of the same concentrations of NSAIDs were investigated in natural algal assemblages in microcosms. According to the changes of chlorophyll-a content, unicellular cyanobacteria seemed to be more tolerant to NSAIDs than eukaryotic algae in laboratory experiments. Growth of eukaryotic algae was reduced by all drugs, the cryptomonad C. ovata was the most sensitive to NSAIDs, while the flagellated green alga H. pluvialis was more sensitive than the non-motile green alga D. communis. NSAID treatments had weaker impact in the natural assemblages dominated by cyanobacteria than in the ones dominated by eukaryotic algae, confirming the results of laboratory experiments. Diversity and number of functional groups did not change notably in cyanobacteria dominated assemblages, while they decreased significantly in eukaryotic algae dominated ones compared to controls. The results highlight that cyanobacteria (especially unicellular ones) are less sensitive to the studied, mostly hardly degradable NSAIDs, which suggest that their accumulation in water bodies may contribute to the expansion of cyanobacterial mass productions in appropriate environmental circumstances by pushing back eukaryotic algae. Thus, these contaminants require special attention during wastewater treatment and monitoring of surface waters. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of copper toxicity using site specific algae and water chemistry: Field validation of laboratory bioassays.

PubMed

Fawaz, Elyssa G; Salam, Darine A; Kamareddine, Lina

2018-07-15

Studies of metal toxicity to microalgae have predominantly been conducted using single non-target algae species and without due regard for the chemistry of the treated waters, leading to ineffective or excessive algaecide treatments. In this study, indigenous multi-algal species (Scenedesmus quadricauda, and Scenedesmus subspicatus and Oscillatoria agardhii) were used in laboratory toxicity bioassays under simulated field water chemistry (pH = 7.2, hardness = 196 mg L -1 as CaCO 3 , and alkalinity = 222 mg L -1 as CaCO 3 ) to determine the optimum copper sulfate treatment dose to control algae growth in an irrigation canal. Toxicity bioassays were conducted using copper sulfate in chelated (with EDTA) and non-chelated (without EDTA) forms to assess the influence of the use of synthetic chelators in toxicity studies. Also, copper toxicity to the indigenous algae species was measured in the non-modified EPA test medium (pH = 7.5, hardness = 92 mg L -1 as CaCO 3 , alkalinity = 10 mg L -1 as CaCO 3 and EDTA= 300 µg L -1 ) to assess the impact of the water chemistry on algae inhibitory algal dosages. Under simulated water chemistry conditions, lower toxicity was measured in the test flasks with the chelated form of copper (96 h- EC 50 = 386.67 µg L -1 as Cu) as compared to those with the non-chelated metal (96 h-EC 50 = 217.17 µg L -1 as Cu). In addition, higher copper toxicity was measured in the test flasks prepared with the non-modified EPA medium using chelated copper (96 h-EC 50 = 65.93 µg L -1 as Cu) as compared to their analogous microcosms with modified water chemistry (96 h-EC 50 = 386.67 µg L -1 as Cu), the increased water hardness and alkalinity in the latter case contributing to the decrease of the metal bioavailability. Results from laboratory experiments showed good correlation with copper dosages used in a small scale field testing to control algae growth, increasing confidence in

Hiero-Dermato-Glyphics: Laboratory Study of the Skin

ERIC Educational Resources Information Center

Roark, Oakley F.

1977-01-01

Explains several laboratory exercises using the skin, including the mapping of receptors, counting of sweat glands, computation of total skin area, comparison of various animal skins, measurement of the palm triradius angle, and study of epidermal ridges (dermatoglyphics) in males and females. (CS)

Laboratory Practices of Beginning Secondary Science Teachers: A Five-Year Study

ERIC Educational Resources Information Center

Wong, Sissy S.; Firestone, Jonah B.; Luft, Julie A.; Weeks, Charles B.

2013-01-01

During the beginning years of teaching, science teachers develop the knowledge and skills needed to design and implement science laboratories. In this regard, this quantitative study focused on the reported laboratory practices of 61 beginning secondary science teachers who participated in four different induction programs. The results…

Developing Medicare Competitive Bidding: A Study of Clinical Laboratories

PubMed Central

Hoerger, Thomas J.; Meadow, Ann

1997-01-01

Competitive bidding to derive Medicare fees promises several advantages over administered fee systems. The authors show how incentives for cost savings, quality, and access can be incorporated into bidding schemes, and they report on a study of the clinical laboratory industry conducted in preparation for a bidding demonstration. The laboratory industry is marked by variable concentration across geographic markets and, among firms themselves, by social and economic heterogeneity. The authors conclude that these conditions can be accommodated by available bidding design options and by careful selection of bidding markets. PMID:10180003

Laboratory studies of imitation/field studies of tradition: towards a synthesis in animal social learning.

PubMed

Galef, Bennett G

2015-03-01

Here I discuss: (1) historical precedents that have resulted in comparative psychologists accepting the two-action method as the "gold standard" in laboratory investigations of imitation learning, (2) evidence suggesting that the two-action procedure may not be adequate to answer questions concerning the role of imitation in the development of traditional behaviors of animals living in natural habitat, and (3) an alternative approach to the laboratory study of imitation that might increase the relevance of laboratory studies of imitation to the work of behavioral ecologists/primatologists interested in animal traditions and their relationship to human cumulative culture. This article is part of a Special Issue entitled: Tribute to Tom Zentall. Copyright © 2014 Elsevier B.V. All rights reserved.

A Manpower Study of Technical Personnel in Hospital Clinical Laboratories. Final Report.

ERIC Educational Resources Information Center

Harkness, James P., And Others

As one of the efforts related to closing the gap between the growing demands for clinical laboratory workers and the supply of well-trained workers, the volume and quality of laboratory procedures and the general characteristics of workers in North Carolina hospitals were studied. Approaches to the study included tests on "unknowns" by…

Knowledge, attitude, and practice (KAP) of 'teaching laboratory' technicians towards laboratory safety and waste management: a pilot interventional study.

PubMed

El-Gilany, A-H; El-Shaer, S; Khashaba, E; El-Dakroory, S A; Omar, N

2017-06-01

A quasi-experimental study was performed on 20 technicians working in the Faculty of Medicine, Mansoura University, Egypt. The knowledge, attitude, and practice (KAP) of laboratory technicians was measured before and two months after enrolling them in an intervention programme about laboratory best practice procedures. The programme addressed laboratory safety and medical waste management. The assessment was performed using a validated Arabic self-administered questionnaire. Pre- and post-intervention scores were compared using non-parametric tests. There are significant increases in the scores of KAP after implementation of the training programme. Copyright © 2017 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

[Tuberculosis Laboratory Surveillance Network (TuLSA) study group. The first step for national tuberculosis laboratory surveillance: Ankara, 2011].

PubMed

Sezen, Figen; Albayrak, Nurhan; Özkara, Şeref; Karagöz, Alper; Alp, Alpaslan; Duyar Ağca, Filiz; İnan Süer, Asiye; Müderris, Tuba; Ceyhan, İsmail; Durmaz, Rıza; Ertek, Mustafa

2015-04-01

The most effective method for monitoring country-level drug resistance frequency and to implement the necessary control measures is the establishment of a laboratory-based surveillance system. The aim of this study was to summarize the follow up trend of the drug-resistant tuberculosis (TB) cases, determine the load of resistance and evaluate the capacities of laboratories depending on laboratory quality assurance system for the installation work of National Tuberculosis Laboratory Surveillance Network (TuLSA) which has started in Ankara in 2011. TuLSA studies was carried out under the coordination of National Tuberculosis Reference Laboratory (NRL) with the participation of TB laboratories and dispensaries. Specimens of TB patients, reported from health institutions, were followed in TB laboratories, and the epidemiological information was collected from the dispensaries. One isolate per patient with the drug susceptibility test (DST) results were sent to NRL from TB laboratories and in NRL the isolates were rechecked with the genotypical (MTBDRplus, Hain Lifescience, Germany) and phenotypical (MGIT 960, BD, USA) DST methods. Molecular epidemiological analysis were also performed by spoligotyping and MIRU/VNTR. Second-line DST was applied to the isolates resistant to rifampin. A total of 1276 patients were reported between January 1st to December 31th 2011, and 335 cases were defined as "pulmonary TB from Ankara province". The mean age of those patients was 43.4 ± 20 years, and 67.5% were male. Three hundred seventeen (94.6%) patients were identified as new cases. The average sample number obtained from pulmonary TB cases was 3.26 ± 2.88, and 229 (68.3%) of them was culture positive. DST was applied to all culture positive isolates; 90.4% (207/229) of cases were susceptible to the five drugs tested (ethambutol, isoniazid, pyrazinamide, rifampicin, streptomycin). Eight (3.5%) of the isolates were multidrug-resistant (MDR-TB), while no extensively drug

Role of microbial activity in Fe(III) hydroxysulfate mineral transformations in an acid mine drainage-impacted site from the Dabaoshan Mine.

PubMed

Bao, Yanping; Guo, Chuling; Lu, Guining; Yi, Xiaoyun; Wang, Han; Dang, Zhi

2018-03-01

Fe(III) hydroxysulfate minerals are secondary minerals commonly found in acid mine drainage (AMD) sites and have a major impact on water and soil quality in these environments. While previous studies showed that the Fe(III) hydroxysulfate mineral transformation could be mediated by some bacterial strains under laboratory conditions, the role of indigenous microbial activity in Fe(III) hydroxysulfate mineral transformation in natural environment has received little attention. In this study, microcosms were constructed with AMD-affected river water and sediment from the Dabaoshan Mine that was either left unamended or enriched with nutrients (lactate, nitrogen, and phosphorus (LNP)) and biosynthetic minerals (schwertmannite or jarosite). The results show that microbial activity played a decisive role in the mineralogical transformation of schwertmannite/jarosite in the AMD-contaminated site when organic carbon was available. The accumulation of Fe(II) and sulfide in microcosms amended with LNP indicates that schwertmannite/jarosite transformation is mediated by microbial reduction. XRD, SEM and FTIR analyses suggest that schwertmannite was completely transformed to goethite in the Sch-LNP microcosms at the end of their incubation. Jarosite in the Jar-LNP microcosms was also transformed to goethite, but at a much slower rate than schwertmannite. Bacterial community analysis reveals that the stimulated indigenous bacteria promote the mineralogical transformation of schwertmannite/jarosite. Most of these bacteria, including Geobacter, Desulfosporosinus, Geothrix, Desulfurispora, Desulfovibrio, and Anaeromyxobacter, are known to reduce iron and/or sulfate. The mineralogical transformation of schwertmannite and jarosite exerts significant control on the geochemistry of AMD-contaminated systems. Copyright © 2018 Elsevier B.V. All rights reserved.

Assessing the Response of Nematode Communities to Climate Change-Driven Warming: A Microcosm Experiment.

PubMed

Gingold, Ruth; Moens, Tom; Rocha-Olivares, Axayácatl

2013-01-01

Biodiversity has diminished over the past decades with climate change being among the main responsible factors. One consequence of climate change is the increase in sea surface temperature, which, together with long exposure periods in intertidal areas, may exceed the tolerance level of benthic organisms. Benthic communities may suffer structural changes due to the loss of species or functional groups, putting ecological services at risk. In sandy beaches, free-living marine nematodes usually are the most abundant and diverse group of intertidal meiofauna, playing an important role in the benthic food web. While apparently many functionally similar nematode species co-exist temporally and spatially, experimental results on selected bacterivore species suggest no functional overlap, but rather an idiosyncratic contribution to ecosystem functioning. However, we hypothesize that functional redundancy is more likely to observe when taking into account the entire diversity of natural assemblages. We conducted a microcosm experiment with two natural communities to assess their stress response to elevated temperature. The two communities differed in diversity (high [HD] vs. low [LD]) and environmental origin (harsh vs. moderate conditions). We assessed their stress resistance to the experimental treatment in terms of species and diversity changes, and their function in terms of abundance, biomass, and trophic diversity. According to the Insurance Hypothesis, we hypothesized that the HD community would cope better with the stressful treatment due to species functional overlap, whereas the LD community functioning would benefit from species better adapted to harsh conditions. Our results indicate no evidence of functional redundancy in the studied nematofaunal communities. The species loss was more prominent and size specific in the HD; large predators and omnivores were lost, which may have important consequences for the benthic food web. Yet, we found evidence for

Clinical laboratory studies of disinfection with Sporicidin.

PubMed Central

Isenberg, H D

1985-01-01

The clinical microbiology laboratory evaluation of disinfectants can serve as a guide for their application to reduce hospital-acquired infections. The use of Sporicidin, a glutaraldehyde-phenol formulation, was evaluated by the application of modified MIC and MBC determinations for standard organisms. In addition, the effect of this formulation on bacteria that may proliferate in water at ambient temperatures was studied. This investigation indicated that such studies can help the clinical microbiologist to guide the use of disinfectants and sterilants for the maintenance of a safe hospital environment. PMID:3932457

An Experimental Study of a BSCS-Style Laboratory Approach for University General Biology.

ERIC Educational Resources Information Center

Leonard, William H.

1983-01-01

A Biological Sciences Curriculum Study (BSCS) inquiry approach for university general biology laboratory was tested against a well-established commercial program judged to be highly directive. The BSCS was found to be more effective in learning biology laboratory concepts than the commercial program as measured by a laboratory concepts test.…

Safety in the Chemical Laboratory. Epidemiology of Accidents in Academic Chemistry Laboratories, Part 2. Accident Intervention Study, Legal Aspects, and Observations.

ERIC Educational Resources Information Center

Hellmann, Margaret A.; And Others

1986-01-01

Reports on a chemistry laboratory accident intervention study conducted throughout the state of Colorado. Addresses the results of an initial survey of institutions of higher learning. Discusses some legal aspects concerning academic chemistry accidents. Provides some observations about academic chemistry laboratory accidents on the whole. (TW)

Tracer Studies In A Laboratory Beach Subjected To Waves

EPA Science Inventory

This work investigated the washout of dissolved nutrients from beaches due to waves by conducting tracer studies in a laboratory beach facility. The effects of waves were studied in the case where the beach was subjected to the tide, and that in which no tidal action was present...

Preliminary study: Formaldehyde exposure in laboratories of Sharjah university in UAE

PubMed Central

Ahmed, Hafiz Omer

2011-01-01

Objectives Laboratory technicians, students, and instructors are at high risk, because they deal with chemicals including formaldehyde. Thus, this preliminary study was conducted to measure the concentration of formaldehyde in the laboratories of the University of Sharjah in UAE. Materials and Methods: Thirty-two air samples were collected and analyzed for formaldehyde using National Institute for Occupational Safety and Health (NIOSH) method 3500. In this method, formaldehyde reacts with chromotropic acid in the presence of sulfuric acid to form a colored solution. The absorbance of the colored solution is read in spectrophotometer at wavelength 580 nm and is proportional to the quantity of the formaldehyde in the solution. Results: For the anatomy laboratory and in the presence of the covered cadaver, the mean concentration of formaldehyde was found to be 0.100 ppm with a range of 0.095–0.105 ppm. Whereas for the other laboratories, the highest mean concentration of formaldehyde was 0.024 ppm in the general microbiology laboratory and the lowest mean concentration of formaldehyde was 0.001 ppm in the environmental health laboratory. The 8-hour (time-weighted average) concentration of formaldehyde was found to be ranging between 0.0003 ppm in environmental health laboratory and 0.026 ppm in the anatomy laboratory. Conclusions: The highest level of concentration of formaldehyde in the presence of the covered cadaver in anatomy laboratory exceeded the recommended ceiling standard established by USA-NIOSH which is 0.1 ppm, but below the ceiling standard established by American Conference of Governmental Industrial Hygienists which is 0.3 ppm. Thus, it is recommended that formaldehyde levels should be measured periodically specially during the dissection in the anatomy laboratory, and local exhaust ventilation system should be installed and personal protective equipment such as safety glass and gloves should be available and be used to prevent direct skin or eye

Peeking under the Iron Curtain: Development of a Microcosm for Imaging the Colonization of Steel Surfaces by Mariprofundus sp. Strain DIS-1, an Oxygen-Tolerant Fe-Oxidizing Bacterium

PubMed Central

Adaktylou, Irini J.; Emerson, David

2016-01-01

ABSTRACT Microbially influenced corrosion (MIC) is a major cause of damage to steel infrastructure in the marine environment. Despite their ability to grow directly on Fe(II) released from steel, comparatively little is known about the role played by neutrophilic iron-oxidizing bacteria (FeOB). Recent work has shown that FeOB grow readily on mild steel (1018 MS) incubated in situ or as a substrate for pure cultures in vitro; however, details of how they colonize steel surfaces are unknown yet are important for understanding their effects. In this study, we combine a novel continuously upwelling microcosm with confocal laser scanning microscopy (CLSM) to determine the degree of colonization of 1018 MS by the marine FeOB strain DIS-1. 1018 MS coupons were incubated with sterile seawater (pH 8) inoculated with strain DIS-1. Incubations were performed both under oxic conditions and in an anoxic-to-oxic gradient. Following incubations of 1 to 10 days, the slides were removed from the microcosms and stained to visualize both cells and stalk structures. Stained coupons were visualized by CLSM after being mounted in a custom frame to preserve the three-dimensional structure of the biofilm. The incubation of 1018 MS coupons with strain DIS-1 under oxic conditions resulted in initial attachment of cells within 2 days and nearly total coverage of the coupon with an ochre film within 5 days. CLSM imaging revealed a nonadherent biofilm composed primarily of the Fe-oxide stalks characteristic of strain DIS-1. When incubated with elevated concentrations of Fe(II), DIS-1 colonization of 1018 MS was inhibited. IMPORTANCE These experiments describe the growth of a marine FeOB in a continuous culture system and represent direct visualizations of steel colonization by FeOB. We anticipate that these experiments will lay the groundwork for studying the mechanisms by which FeOB colonize steel and help to elucidate the role played by marine FeOB in MIC. These observations of the

Peeking under the Iron Curtain: Development of a Microcosm for Imaging the Colonization of Steel Surfaces by Mariprofundus sp. Strain DIS-1, an Oxygen-Tolerant Fe-Oxidizing Bacterium.

PubMed

Mumford, Adam C; Adaktylou, Irini J; Emerson, David

2016-11-15

Microbially influenced corrosion (MIC) is a major cause of damage to steel infrastructure in the marine environment. Despite their ability to grow directly on Fe(II) released from steel, comparatively little is known about the role played by neutrophilic iron-oxidizing bacteria (FeOB). Recent work has shown that FeOB grow readily on mild steel (1018 MS) incubated in situ or as a substrate for pure cultures in vitro; however, details of how they colonize steel surfaces are unknown yet are important for understanding their effects. In this study, we combine a novel continuously upwelling microcosm with confocal laser scanning microscopy (CLSM) to determine the degree of colonization of 1018 MS by the marine FeOB strain DIS-1. 1018 MS coupons were incubated with sterile seawater (pH 8) inoculated with strain DIS-1. Incubations were performed both under oxic conditions and in an anoxic-to-oxic gradient. Following incubations of 1 to 10 days, the slides were removed from the microcosms and stained to visualize both cells and stalk structures. Stained coupons were visualized by CLSM after being mounted in a custom frame to preserve the three-dimensional structure of the biofilm. The incubation of 1018 MS coupons with strain DIS-1 under oxic conditions resulted in initial attachment of cells within 2 days and nearly total coverage of the coupon with an ochre film within 5 days. CLSM imaging revealed a nonadherent biofilm composed primarily of the Fe-oxide stalks characteristic of strain DIS-1. When incubated with elevated concentrations of Fe(II), DIS-1 colonization of 1018 MS was inhibited. These experiments describe the growth of a marine FeOB in a continuous culture system and represent direct visualizations of steel colonization by FeOB. We anticipate that these experiments will lay the groundwork for studying the mechanisms by which FeOB colonize steel and help to elucidate the role played by marine FeOB in MIC. These observations of the interaction between an Fe

BIOTRANSFORMATION OF GASOLINE-CONTAMINATED GROUNDWATER UNDER MIXED ELECTRON-ACCEPTOR CONDITIONS

EPA Science Inventory

This project represents a cooperative effort between the University of Waterloo and the U.S. Environmental Protection Agency. This report summarizes research conducted using both laboratory batch microcosms and field-scale sheet-piling cells to evaluate whether bioremediation of...

[Quality assessment of microscopic examination in tuberculosis diagnostic laboratories: a preliminary study].

PubMed

Simşek, Hülya; Ceyhan, Ismail; Tarhan, Gülnur; Güner, Uğur

2010-10-01

Recently, the diagnosis of pulmonary tuberculosis (TB) has based on smear microscopy in the Direct Observed Treatment Strategy (DOTS) programme which provides the basis of treatment worldwide. Microscopic detection of AFB (Acid-Fast Bacilli) is one of the main components in the National TB Control Programmes (NTCP). Precision level in microscopy procedures and evaluations are the most important steps for accurate diagnosis of the disease and to initiate proper treatment. Therefore, the external quality assessment (EQA) is the most important implement to provide the reliability and validity of tests. In countries where NTCP are performed, this task is fulfilled by the National Reference Laboratories (NRL) according to the guidelines of the World Health Organization (WHO). For this purpose a pilot study was initiated by the central NRL of Turkey for EQA of AFB smear microscopy as part of the NTCP on January 1, 2005. A total of 5 laboratories of which 2 were district TB laboratories (A, B), 2 were tuberculosis control dispensaries (C, D), 1 was a national reference laboratory (E), participated in this study. Blind re-checking method (re-examination of randomly selected slides) was used for the evaluation, and the slides were sent to the central NRL with 3 months interval, four times a year, selected according to LQAS (Lot Quality Assurance Sampling) guides. In the re-evaluation of the slides, false positivity (FP), false negativity (FN) and quantification errors (QE) were noted. Laboratory A, sent totally 525 slides between January 1, 2005 and April 1, 2008. In the result of re-checking, 514 (97.9%) slides were found concordant, and 11 (2.1%) were discordant (10 FP, 1 FN). Laboratory B, participated in the study between October 1, 2005 and July 1, 2006 and of the 67 re-examined slides, 60 (89.5%) were concordant and 7 (10.5%) were discordant (2 FP, 0 FN, 5 QE). Laboratory C, sent 235 slides between January 1, 2005 and April 1, 2006; of them 218 (92.8%) were detected

How toxic is coal ash? A laboratory toxicity case study

DOE PAGES

Sherrard, Rick M.; Carriker, Neil; Greeley, Jr., Mark Stephen

2014-12-08

Under a consent agreement among the Environmental Protection Agency (EPA) and proponents both for and against stricter regulation, EPA is to issue a new coal ash disposal rule by the end of 2014. Laboratory toxicity investigations often yield conservative estimates of toxicity because many standard test species are more sensitive than resident species, thus could provide information useful to the rule-making. However, few laboratory studies of coal ash toxicity are available; most studies reported in the literature are based solely on field investigations. In this paper, we describe a broad range of toxicity studies conducted for the Tennessee Valley Authoritymore » (TVA) Kingston ash spill, results of which help provide additional perspective on the toxicity of coal ash.« less

BIODEGRADATION OF AROMATIC HYDROCARBONS BY AQUIFER MICROORGANISMS UNDER DENITRIFYING CONDITIONS

EPA Science Inventory

A series of laboratory tests were conducted to evaluate whether denitrification would be a suitable alternative for biorestoration of an aquifer contaminated with JP-4 jet fuel. Microcosms were prepared from both uncontaminated and contaminated-aquifer material from the site, in ...

Teaching Population Growth Using Cultures of Vinegar Eels, "Turbatrix aceti" (Nematoda)

ERIC Educational Resources Information Center

Wallace, Robert L.

2005-01-01

A simple laboratory exercise is presented that follows the population growth of the common vinegar eel, "Turbatrix aceti" (Nematoda), in a microcosm using a simple culture medium. It lends itself to an exercise in a single semester course. (Contains 4 figures.)

Impact of Oil on Bacterial Community Structure in Bioturbated Sediments

PubMed Central

Stauffert, Magalie; Cravo-Laureau, Cristiana; Jézéquel, Ronan; Barantal, Sandra; Cuny, Philippe; Gilbert, Franck; Cagnon, Christine; Militon, Cécile; Amouroux, David; Mahdaoui, Fatima; Bouyssiere, Brice; Stora, Georges; Merlin, François-Xavier; Duran, Robert

2013-01-01

Oil spills threaten coastlines where biological processes supply essential ecosystem services. Therefore, it is crucial to understand how oil influences the microbial communities in sediments that play key roles in ecosystem functioning. Ecosystems such as sediments are characterized by intensive bioturbation due to burrowing macrofauna that may modify the microbial metabolisms. It is thus essential to consider the bioturbation when determining the impact of oil on microbial communities. In this study, an experimental laboratory device maintaining pristine collected mudflat sediments in microcosms closer to true environmental conditions – with tidal cycles and natural seawater – was used to simulate an oil spill under bioturbation conditions. Different conditions were applied to the microcosms including an addition of: standardized oil (Blend Arabian Light crude oil, 25.6 mg.g−1 wet sediment), the common burrowing organism Hediste (Nereis) diversicolor and both the oil and H. diversicolor. The addition of H. diversicolor and its associated bioturbation did not affect the removal of petroleum hydrocarbons. After 270 days, 60% of hydrocarbons had been removed in all microcosms irrespective of the H. diversicolor addition. However, 16S-rRNA gene and 16S-cDNA T-RFLP and RT-PCR-amplicon libraries analysis showed an effect of the condition on the bacterial community structure, composition, and dynamics, supported by PerMANOVA analysis. The 16S-cDNA libraries from microcosms where H. diversicolor was added (oiled and un-oiled) showed a marked dominance of sequences related to Gammaproteobacteria. However, in the oiled-library sequences associated to Deltaproteobacteria and Bacteroidetes were also highly represented. The 16S-cDNA libraries from oiled-microcosms (with and without H. diversicolor addition) revealed two distinct microbial communities characterized by different phylotypes associated to known hydrocarbonoclastic bacteria and dominated by

Impact of oil on bacterial community structure in bioturbated sediments.

PubMed

Stauffert, Magalie; Cravo-Laureau, Cristiana; Jézéquel, Ronan; Barantal, Sandra; Cuny, Philippe; Gilbert, Franck; Cagnon, Christine; Militon, Cécile; Amouroux, David; Mahdaoui, Fatima; Bouyssiere, Brice; Stora, Georges; Merlin, François-Xavier; Duran, Robert

2013-01-01

Oil spills threaten coastlines where biological processes supply essential ecosystem services. Therefore, it is crucial to understand how oil influences the microbial communities in sediments that play key roles in ecosystem functioning. Ecosystems such as sediments are characterized by intensive bioturbation due to burrowing macrofauna that may modify the microbial metabolisms. It is thus essential to consider the bioturbation when determining the impact of oil on microbial communities. In this study, an experimental laboratory device maintaining pristine collected mudflat sediments in microcosms closer to true environmental conditions--with tidal cycles and natural seawater--was used to simulate an oil spill under bioturbation conditions. Different conditions were applied to the microcosms including an addition of: standardized oil (Blend Arabian Light crude oil, 25.6 mg.g⁻¹ wet sediment), the common burrowing organism Hediste (Nereis) diversicolor and both the oil and H. diversicolor. The addition of H. diversicolor and its associated bioturbation did not affect the removal of petroleum hydrocarbons. After 270 days, 60% of hydrocarbons had been removed in all microcosms irrespective of the H. diversicolor addition. However, 16S-rRNA gene and 16S-cDNA T-RFLP and RT-PCR-amplicon libraries analysis showed an effect of the condition on the bacterial community structure, composition, and dynamics, supported by PerMANOVA analysis. The 16S-cDNA libraries from microcosms where H. diversicolor was added (oiled and un-oiled) showed a marked dominance of sequences related to Gammaproteobacteria. However, in the oiled-library sequences associated to Deltaproteobacteria and Bacteroidetes were also highly represented. The 16S-cDNA libraries from oiled-microcosms (with and without H. diversicolor addition) revealed two distinct microbial communities characterized by different phylotypes associated to known hydrocarbonoclastic bacteria and dominated by Gammaproteobacteria

Response of sago pondweed, a submerged aquatic macrophyte, to herbicides in three laboratory culture systems

USGS Publications Warehouse

Fleming, W.J.; Ailstock, M.S.; Momot, J.J.; Norman, C.M.; Gorsuch, Joseph W.; Lower, William R.; Wang, Wun-cheng; Lewis, M.A.

1991-01-01

The phytotoxicity of atrazine, paraquat, glyphosate, and alachlor to sago pondweed (Potamogeton pectinatus), a submerged aquatic macrophyte, was tested under three types of laboratory culture conditions. In each case, tests were conducted in static systems, the test period was four weeks, and herbicide exposure was chronic, resulting from a single addition of herbicide to the test vessels at the beginning of the test period. The three sets of test conditions employed were(1) axenic cultures in 125-mL flasks containing a nutrient media and sucrose; (2) a microcosm system employing 18.9-L buckets containing a sand, shell, and peat substrate; and (3) an algae-free system employing O.95-L jars containing reconstituted freshwater and a nutrient agar substrate. The primary variable measured was biomass production. Plants grew well in all three test systems, with biomass of untreated plants increasing by a factor of about 5 to 6.5 during the four-week test period. Biomass production in response to herbicide exposure differed significantly among culture systems, which demonstrates the need for a standardized testing protocol for evaluating the effects of toxics on submerged aquatic plants.

SPRUCE Deep Peat Microbial Diversity, CO2 and CH4 Production in Response to Nutrient, Temperature, and pH Treatments during Incubation Studies.

DOE Data Explorer

A., Kluber Laurel [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Allen, Samantha A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hendershot, Nicholas [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hanson, Paul J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Schadt, Christopher W. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

2014-09-01

This data set contains the results of a microcosm incubation study on deep peat collected from the SPRUCE experimental site in the S1 Bog in September 2014. Microcosms were monitored for CO2 and CH4 production, and microbial community dynamics were assessed using qPCR and amplicon sequencing.The experiment was designed with a full factorial design with elevated temperature, nitrogen (N), (P), and pH treatments was used with samples from each transect serving replicates. In all, 96 microcosms were constructed to account for the 16 treatment combinations (N x P x pH x temperature), 2 time points, and 3 replicates. Temperature treatments were 6 °C, to mimic the SPRUCE ambient plot temperatures, and 15 °C to mimic the SPRUCE +9 °C treatment.

Characterization of bacterial functional groups and microbial activity in microcosms with glyphosate application

NASA Astrophysics Data System (ADS)

Moyano, Sofia; Bonetto, Mariana; Baigorria, Tomas; Pegoraro, Vanesa; Ortiz, Jimena; Faggioli, Valeria; Conde, Belen; Cazorla, Cristian; Boccolini, Monica

2017-04-01

Glyphosate is a worldwide used herbicide as c. 90% of transgenic crops are tolerant to it. Microbial degradation of glyphosate molecule in soil is considered the most important process that determines its persistence in the environment. However, the impact of this herbicide on target groups of soil biota remains poorly understood. Our objective was to characterize the abundance of bacterial groups and global microbial activity, under controlled conditions with application of increasing doses of glyphosate. A bioassay was carried out in microcosms using an agricultural soil (Typic Argiudoll) with registered history of glyphosate application from National Institute of Agricultural Technology (INTA, EEA Marcos Juarez, Argentina). Glyphosate of commercial formulation (74.7%) was used and the following treatments were evaluated: Soil without glyphosate (control), and Soil with doses equivalent to 1.12 and 11.2 kg ai ha-1. Microbiological parameters were estimated at 3, 7, 14 and 21 days after herbicide application by counting heterotrophic, cellulolytic, nitrogen fixing (N), and nitrifying bacteria; and fluorescein diacetate hydrolysis (FDA), microbial respiration (MR) and microbial biomass (C-BM). The N cycle related bacteria showed greater sensitivity to glyphosate with significant increases in abundance. On the other hand the C cycle parameters were strongly conditioned by the time elapsed since the application of the herbicide, as did the MR. The FDA declined with the highest dose, while the C-BM was not affected. Therefore, we conclude that in the studied experimental conditions glyphosate stimulated bacterial growth (i.e. target abundances) representing a source of N, C and nutrients. On the other hand, enzymatic activity (FDA) decreased when glyphosate was applied in the highest dose, whereas, it had no effect on the MR nor C-BM, which could be attributable to the organic matter content of the soil. However, future research in field conditions is necessary, for

Temporal variation in temperature determines disease spread and maintenance in Paramecium microcosm populations

PubMed Central

Duncan, Alison B.; Fellous, Simon; Kaltz, Oliver

2011-01-01

The environment is rarely constant and organisms are exposed to temporal and spatial variations that impact their life histories and inter-species interactions. It is important to understand how such variations affect epidemiological dynamics in host–parasite systems. We explored effects of temporal variation in temperature on experimental microcosm populations of the ciliate Paramecium caudatum and its bacterial parasite Holospora undulata. Infected and uninfected populations of two P. caudatum genotypes were created and four constant temperature treatments (26°C, 28°C, 30°C and 32°C) compared with four variable treatments with the same mean temperatures. Variable temperature treatments were achieved by alternating populations between permissive (23°C) and restrictive (35°C) conditions daily over 30 days. Variable conditions and high temperatures caused greater declines in Paramecium populations, greater fluctuations in population size and higher incidence of extinction. The additional effect of parasite infection was additive and enhanced the negative effects of the variable environment and higher temperatures by up to 50 per cent. The variable environment and high temperatures also caused a decrease in parasite prevalence (up to 40%) and an increase in extinction (absence of detection) (up to 30%). The host genotypes responded similarly to the different environmental stresses and their effect on parasite traits were generally in the same direction. This work provides, to our knowledge, the first experimental demonstration that epidemiological dynamics are influenced by environmental variation. We also emphasize the need to consider environmental variance, as well as means, when trying to understand, or predict population dynamics or range. PMID:21450730

Rapid bacterial colonization of low-density polyethylene microplastics in coastal sediment microcosms.

PubMed

Harrison, Jesse P; Schratzberger, Michaela; Sapp, Melanie; Osborn, A Mark

2014-09-23

Synthetic microplastics (≤5-mm fragments) are emerging environmental contaminants that have been found to accumulate within coastal marine sediments worldwide. The ecological impacts and fate of microplastic debris are only beginning to be revealed, with previous research into these topics having primarily focused on higher organisms and/or pelagic environments. Despite recent research into plastic-associated microorganisms in seawater, the microbial colonization of microplastics in benthic habitats has not been studied. Therefore, we employed a 14-day microcosm experiment to investigate bacterial colonization of low-density polyethylene (LDPE) microplastics within three types of coastal marine sediment from Spurn Point, Humber Estuary, U.K. Bacterial attachment onto LDPE within sediments was demonstrated by scanning electron microscopy and catalyzed reporter deposition fluorescence in situ hybridisation (CARD-FISH). Log-fold increases in the abundance of 16S rRNA genes from LDPE-associated bacteria occurred within 7 days with 16S rRNA gene numbers on LDPE surfaces differing significantly across sediment types, as shown by quantitative PCR. Terminal-restriction fragment length polymorphism (T-RFLP) analysis demonstrated rapid selection of LDPE-associated bacterial assemblages whose structure and composition differed significantly from those in surrounding sediments. Additionally, T-RFLP analysis revealed successional convergence of the LDPE-associated communities from the different sediments over the 14-day experiment. Sequencing of cloned 16S rRNA genes demonstrated that these communities were dominated after 14 days by the genera Arcobacter and Colwellia (totalling 84-93% of sequences). Attachment by Colwellia spp. onto LDPE within sediments was confirmed by CARD-FISH. These results demonstrate that bacteria within coastal marine sediments can rapidly colonize LDPE microplastics, with evidence for the successional formation of plastisphere-specific bacterial

An international study of how laboratories handle and evaluate patient samples after detecting an unexpected APTT prolongation.

PubMed

Ajzner, Éva; Rogic, Dunja; Meijer, Piet; Kristoffersen, Ann Helen; Carraro, Paolo; Sozmen, Eser; Faria, Ana Paula; Sandberg, Sverre

2015-09-01

An unexpectedly detected prolonged activated partial thromboplastin time (APTT) can be a harmless laboratory finding, but can also reflect a thrombotic tendency or a bleeding disorder. The assistance of laboratory professionals in the interpretation of an unexpectedly detected prolonged APTT (uAPTT) is often required. The way in which uAPTTs are evaluated in laboratories was assessed in this international study with the aim of determining whether laboratory professionals are able to fulfill this need. Postanalytical practices after uAPTT were investigated and the mixing study methodology (if used) was studied by circulating a case report with a questionnaire to staff in the invited laboratories. In addition, the interpretations of those staff regarding the presence or absence of inhibitors in three APTT mixing study scenarios were examined. Large within- and between-country variations were detected in both postanalytical practices and mixing study methodologies among the 990 responding laboratories, 90% of which were in 13 countries. Shortcomings regarding the investigation of uAPTTs leading to potentially incorrect or delayed clinical diagnoses were found in 88% of the laboratories. Of the laboratories to which the interpretative questions were sent, 49% interpreted all mixing study scenarios correctly. uAPTTs were investigated appropriately and all mixing study scenarios interpreted correctly in parallel in only 9.6% of the participating laboratories. The clinical requirement for the assistance of laboratory professionals in the interpretation of uAPTTs cannot be met at most of the participating laboratories. Laboratory professionals should be trained in the evaluation of ordinary laboratory tests, such as that for uAPTTs.

Report of the Field and Laboratory Utilization Study Group. Appendix

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1975-12-01

These appendices (ERDA organization and management, summary of other resources, and FLU study considerations/inputs) provide detailed and quantitative information in support of the findings and recommendations presented in the report of the field and laboratory utilization study group. (RWR)

Influence of phosphate and copper on reductive dechlorination of thiobencarb in California rice field soils.

PubMed

Gunasekara, Amrith S; Tenbrook, Patti L; Palumbo, Amanda J; Johnson, Catherine S; Tjeerdema, Ronald S

2005-12-28

The potential for reductive dechlorination of the herbicide thiobencarb (TB) by microbes and its prevention in saturated anaerobic rice field soils was examined in laboratory microcosms. TB is effective in controlling both annual grasses and broadleaf weeds. In anoxic microcosms, TB was effectively degraded within 30 days to its dechlorinated product, deschlorothiobencarb (DTB), in two Sacramento Valley rice field soils. TB dechlorination, and subsequent degradation, followed pseudo-zero- (lag phase) and first-order (degradation phase) kinetics. Logistic regression analysis (r2 > 0.841) produced a half-life (t(1/2)) in nonsterile soils ranging from 10 to 15 days, which was also observed when microcosms were amended with low concentrations (<3 mg L(-1)) of copper (Cu2+; as the fungicides Cu(OH)2 and CuSO4.5H2O). High Cu2+ concentrations (>40 mg L(-1)) were added to the microcosms to determine if copper toxicity to dechlorinating microbes is concentration dependent within the range used. After 30 days, the low-copper-amended soils closely resembled the nonsterile experiments to which no Cu2+ was added while the high-copper-amended microcosms were similar to the sterile experiment. Microcosms were also separately amended with 5.7 g L(-1) phosphate (PO4(2-); as KH2PO4), a nutrient regularly applied to rice fields. Phosphate-amended experiments also showed TB degradation, but no DTB formation, indicating the phosphate played a role, possibly as a microbial inhibitor or an alternative electron acceptor, in limiting the dechlorination of TB. In summary, TB dechlorination was inhibited at high Cu(OH)2, CuSO4.5H2O, and KH2PO4 concentrations.

Effect of imbalanced nutrients and immigration on Prymnesium parvum community dominance and toxicity: Results from in-lake microcosm experiments

USGS Publications Warehouse

Errera, R.M.; Roelke, D.L.; Kiesling, R.L.; Brooks, B.W.; Grover, J.P.; Schwierzke, L.; Urena-Boeck, F.; Baker, J.W.; Pinckney, J.L.

2008-01-01

Prymnesium parvum, a haptophyte species, forms harmful blooms, including those that have caused severe fish kills in Texas, USA, over the past 6 yr. We studied P. parvum dynamics using in situ microcosm experiments at Lake Possum Kingdom, Texas, during 3 seasons (fall 2004, winter and spring 2005). Experimental treatments included full and partial nutrient enrichment (encompassing nitrogen [N] and phosphorus [P] deficient treatments), P. parvum immigration and combinations of these factors. In the control and N and P deficient treatments, P. parvum populations dominated the community, but only in the N deficient treatments did P. parvum experience a significant growth in the population. In contrast, when nutrients were not limiting, P. parvum tended to lose its competitive edge to other taxa such as chlorophytes, euglenophytes and diatoms, which then dominated the community. Population growth of P. parvum was also stimulated through immigration, but only during the winter experiment, a period of the year when bloom initiation is common. This finding suggests that movement into the water column may be an important process leading to P. parvum bloom initiation. Toxicity of P. parvum to fish was also affected by the nutrient changes: during conditions of no nutrient addition P. parvum was most toxic; intermediate toxicity was observed under N and P deficient conditions, and full nutrient enrichments resulted in nearly non-toxic conditions. ?? Inter-Research 2008.

Laboratory and Space Plasma Studies

NASA Astrophysics Data System (ADS)

Hyman, Ellis

1996-08-01

The work performed by Science Applications International Corporation (SAIC), encompasses a wide range of topics in experimental, computational, and analytical laboratory and space plasma physics. The accomplishments described in this report have been in support of the programs of the Laser Plasma Branch (Code 6730) and other segments of the Plasma Physics Division at the Naval Research Laboratory (NRL) and cover the period 27 September 1993 to August 1, 1996. SAIC's efforts have been supported by sub-contracts or consulting agreements with Pulse Sciences, Inc., Clark Richardson, and Biskup Consulting Engineers, Pharos Technical Enterprises, Plex Corporation, Cornell University, Stevens Institute of Technology, the University of Connecticut, Plasma Materials and Technologies, Inc., and GaSonics International, Inc. In the following discussions section we will describe each of the topics investigated and the results obtained. Much of the research work has resulted in journal publications and NRL Memorandum Reports in which the investigation is described in detail. These reports are included as Appendices to this Final Report.

NETL Extreme Drilling Laboratory Studies High Pressure High Temperature Drilling Phenomena

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyons, K.D.; Honeygan, S.; Moroz, T.H.

2008-12-01

The U.S. Department of Energy's National Energy Technology Laboratory (NETL) established the Extreme Drilling Laboratory to engineer effective and efficient drilling technologies viable at depths greater than 20,000 ft. This paper details the challenges of ultradeep drilling, documents reports of decreased drilling rates as a result of increasing fluid pressure and temperature, and describes NETL's research and development activities. NETL is invested in laboratory-scale physical simulation. Its physical simulator will have capability of circulating drilling fluids at 30,000 psi and 480°F around a single drill cutter. This simulator is not yet operational; therefore, the results will be limited to themore » identification of leading hypotheses of drilling phenomena and NETL's test plans to validate or refute such theories. Of particular interest to the Extreme Drilling Laboratory's studies are the combinatorial effects of drilling fluid pressure, drilling fluid properties, rock properties, pore pressure, and drilling parameters, such as cutter rotational speed, weight on bit, and hydraulics associated with drilling fluid introduction to the rock-cutter interface. A detailed discussion of how each variable is controlled in a laboratory setting will be part of the conference paper and presentation.« less

Relative importance of nutrients and mortality factors on prokaryotic community composition in two lakes of different trophic status: microcosm experiments.

PubMed

Jardillier, Ludwig; Boucher, Delphine; Personnic, Sébastien; Jacquet, Stéphan; Thénot, Aurélie; Sargos, Denis; Amblard, Christian; Debroas, Didier

2005-08-01

The effect of nutrient resources (N and P enrichment) and of different grazing communities on the prokaryotic community composition (PCC) was investigated in two freshwater ecosystems: Sep reservoir (oligomesotrophic) and lake Aydat (eutrophic). An experimental approach using microcosms was chosen, that allowed control of both predation levels, by size fractionation of predators, and resources, by nutrient amendments. Changes in PCC were monitored by fluorescent in situ hybridization (FISH) and terminal-restriction fragment length polymorphism (T-RFLP). The main mortality agents were (i) heterotrophic nanoflagellates and virus-like particles in Aydat and (ii) cladocerans in Sep. All the nutritional elements assayed (N-NO3, P-PO4 and N-NH4) together with prokaryotic production (PP) always accounted for a significant part of the variations in PCC. Overall, prokaryotic diversity was mainly explained by resources in Sep, by a comparable contribution of resources and mortality factors in lake Aydat and, to a lesser extent, by the combined action of both.

Laboratory Based Case Studies: Closer to the Real World

ERIC Educational Resources Information Center

Dinan, Frank J.

2005-01-01

Case-based laboratories offer students the chance to approximate real science. Based on interesting stories that pose problems requiring experimental solutions, they avoid the cookbook approach characteristic of traditional undergraduate laboratory instruction. Instead, case-based laboratories challenge students to develop, as much as possible,…

Laboratory studies of in vivo fluorescence of phytoplankton

NASA Technical Reports Server (NTRS)

Brown, C. A., Jr.; Farmer, F. H.; Jarrett, O., Jr.; Staton, W. L.

1978-01-01

A lidar system is developed that uses four selected excitation wavelengths to induce chlorophyll 'a' fluorescence which is indicative of both the concentration and diversity of phytoplankton. The operating principles of the system and the results of measurements of phytoplankton fluorescence in a controlled laboratory environment are presented. A comparative study of results from lidar fluorosensor laboratory tank tests using representative species of phytoplankton in single and multispecies cultures from each of four color groups reveals that (1) there is good correlation between the fluorescence of chlorophyll 'a' remotely simulated and detected by the lidar system and in-situ measurements using four similar excitation wavelengths in a flow-through fluorometer; (2) good correlation exists between the total chlorophyll 'a' calculated from lidar-fluorosensor data and measurements obtained by the Strickland-Parsons method; and (3) the lidar fluorosensor can provide an index of population diversity.

Response of Bacterioplankton Communities to Cadmium Exposure in Coastal Water Microcosms with High Temporal Variability

PubMed Central

Wang, Kai; Xiong, Jinbo; Chen, Xinxin; Zheng, Jialai; Hu, Changju; Yang, Yina; Zhu, Jianlin

2014-01-01

Multiple anthropogenic disturbances to bacterial diversity have been investigated in coastal ecosystems, in which temporal variability in the bacterioplankton community has been considered a ubiquitous process. However, far less is known about the temporal dynamics of a bacterioplankton community responding to pollution disturbances such as toxic metals. We used coastal water microcosms perturbed with 0, 10, 100, and 1,000 μg liter−1 of cadmium (Cd) for 2 weeks to investigate temporal variability, Cd-induced patterns, and their interaction in the coastal bacterioplankton community and to reveal whether the bacterial community structure would reflect the Cd gradient in a temporally varying system. Our results showed that the bacterioplankton community structure shifted along the Cd gradient consistently after a 4-day incubation, although it exhibited some resistance to Cd at low concentration (10 μg liter−1). A process akin to an arms race between temporal variability and Cd exposure was observed, and the temporal variability overwhelmed Cd-induced patterns in the bacterial community. The temporal succession of the bacterial community was correlated with pH, dissolved oxygen, NO3−-N, NO2−-N, PO43−-P, dissolved organic carbon, and chlorophyll a, and each of these parameters contributed more to community variance than Cd did. However, elevated Cd levels did decrease the temporal turnover rate of community. Furthermore, key taxa, affiliated to the families Flavobacteriaceae, Rhodobacteraceae, Erythrobacteraceae, Piscirickettsiaceae, and Alteromonadaceae, showed a high frequency of being associated with Cd levels during 2 weeks. This study provides direct evidence that specific Cd-induced patterns in bacterioplankton communities exist in highly varying manipulated coastal systems. Future investigations on an ecosystem scale across longer temporal scales are needed to validate the observed pattern. PMID:25326310

Studying Sexual Aggression: A Review of the Evolution and Validity of Laboratory Paradigms

PubMed Central

Davis, Kelly Cue; George, William H.; Nagayama Hall, Gordon C.; Parrott, Dominic J.; Tharp, Andra Teten; Stappenbeck, Cynthia A.

2018-01-01

Objective Researchers have endeavored for decades to develop and implement experimental assessments of sexual aggression and its precursors to capitalize on the many scientific advantages offered by laboratory experiments, such as rigorous control of key variables and identification of causal relationships. The purpose of this review is to provide an overview of and commentary on the evolution of these laboratory-based methods. Conclusions To date, two primary types of sexual aggression laboratory studies have been developed: those that involve behavioral analogues of sexual aggression and those that assess postulated precursors to sexually aggressive behavior. Although the study of sexual aggression in the laboratory is fraught with methodological challenges, validity concerns, and ethical considerations, advances in the field have resulted in greater methodological rigor, more precise dependent measures, and improved experimental validity, reliability, and realism. Because highly effective sexual aggression prevention strategies remain elusive, continued laboratory-based investigation of sexual aggression coupled with translation of critical findings to the development and modification of sexual aggression prevention programs remains an important task for the field. PMID:29675289

Evaluation of Non-Laboratory and Laboratory Prediction Models for Current and Future Diabetes Mellitus: A Cross-Sectional and Retrospective Cohort Study

PubMed Central

Hahn, Seokyung; Moon, Min Kyong; Park, Kyong Soo; Cho, Young Min

2016-01-01

Background Various diabetes risk scores composed of non-laboratory parameters have been developed, but only a few studies performed cross-validation of these scores and a comparison with laboratory parameters. We evaluated the performance of diabetes risk scores composed of non-laboratory parameters, including a recently published Korean risk score (KRS), and compared them with laboratory parameters. Methods The data of 26,675 individuals who visited the Seoul National University Hospital Healthcare System Gangnam Center for a health screening program were reviewed for cross-sectional validation. The data of 3,029 individuals with a mean of 6.2 years of follow-up were reviewed for longitudinal validation. The KRS and 16 other risk scores were evaluated and compared with a laboratory prediction model developed by logistic regression analysis. Results For the screening of undiagnosed diabetes, the KRS exhibited a sensitivity of 81%, a specificity of 58%, and an area under the receiver operating characteristic curve (AROC) of 0.754. Other scores showed AROCs that ranged from 0.697 to 0.782. For the prediction of future diabetes, the KRS exhibited a sensitivity of 74%, a specificity of 54%, and an AROC of 0.696. Other scores had AROCs ranging from 0.630 to 0.721. The laboratory prediction model composed of fasting plasma glucose and hemoglobin A1c levels showed a significantly higher AROC (0.838, P < 0.001) than the KRS. The addition of the KRS to the laboratory prediction model increased the AROC (0.849, P = 0.016) without a significant improvement in the risk classification (net reclassification index: 4.6%, P = 0.264). Conclusions The non-laboratory risk scores, including KRS, are useful to estimate the risk of undiagnosed diabetes but are inferior to the laboratory parameters for predicting future diabetes. PMID:27214034

Antimicrobial action of minocycline microspheres versus 810-nm diode laser on human dental plaque microcosm biofilms.

PubMed

Song, Xiaoqing; Yaskell, Tina; Klepac-Ceraj, Vanja; Lynch, Michael C; Soukos, Nikolaos S

2014-02-01

The purpose of this study is to investigate the antimicrobial effects of minocycline hydrochloride microspheres versus infrared light at 810 nm from a diode laser on multispecies oral biofilms in vitro. These biofilms were grown from dental plaque inoculum (oral microcosms) and were obtained from six systemically healthy individuals with generalized chronic periodontitis. Multispecies biofilms were derived using supra- and subgingival plaque samples from mesio-buccal aspects of premolars and molars exhibiting probing depths in the 4- to 5-mm range and 1- to 2-mm attachment loss. Biofilms were developed anaerobically on blood agar surfaces in 96-well plates using a growth medium of prereduced, anaerobically sterilized brain-heart infusion with 2% horse serum. Minocycline HCl 1 mg microspheres were applied on biofilms on days 2 and 5 of their development. Biofilms were also exposed on days 2 and 5 of their growth to 810-nm light for 30 seconds using a power of 0.8 W in a continuous-wave mode. The susceptibility of microorganisms to minocycline or infrared light was evaluated by a colony-forming assay and DNA probe analysis at different time points. At all time points of survival assessment, minocycline was more effective (>2 log10 colony-forming unit reduction) than light treatment (P <0.002). Microbial analysis did not reveal susceptibility of certain dental plaque pathogens to light, and it was not possible after treatment with minocycline due to lack of bacterial growth. The cumulative action of minocycline microspheres on multispecies oral biofilms in vitro led to enhanced killing of microorganisms, whereas a single exposure of light at 810 nm exhibited minimal and non-selective antimicrobial effects.

Laboratory Experiments and Instrument Intercomparison Studies of Carbonaceous Aerosol Particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidovits, Paul

Aerosols containing black carbon (and some specific types of organic particulate matter) directly absorb incoming light, heating the atmosphere. In addition, all aerosol particles backscatter solar light, leading to a net-cooling effect. Indirect effects involve hydrophilic aerosols, which serve as cloud condensation nuclei (CCN) that affect cloud cover and cloud stability, impacting both atmospheric radiation balance and precipitation patterns. At night, all clouds produce local warming, but overall clouds exert a net-cooling effect on the Earth. The effect of aerosol radiative forcing on climate may be as large as that of the greenhouse gases, but predominantly opposite in sign andmore » much more uncertain. The uncertainties in the representation of aerosol interactions in climate models makes it problematic to use model projections to guide energy policy. The objective of our program is to reduce the uncertainties in the aerosol radiative forcing in the two areas highlighted in the ASR Science and Program Plan. That is, (1) addressing the direct effect by correlating particle chemistry and morphology with particle optical properties (i.e. absorption, scattering, extinction), and (2) addressing the indirect effect by correlating particle hygroscopicity and CCN activity with particle size, chemistry, and morphology. In this connection we are systematically studying particle formation, oxidation, and the effects of particle coating. The work is specifically focused on carbonaceous particles where the uncertainties in the climate relevant properties are the highest. The ongoing work consists of laboratory experiments and related instrument inter-comparison studies both coordinated with field and modeling studies, with the aim of providing reliable data to represent aerosol processes in climate models. The work is performed in the aerosol laboratory at Boston College. At the center of our laboratory setup are two main sources for the production of aerosol

A study of 6S workplace improvement in Ergonomic Laboratory

NASA Astrophysics Data System (ADS)

Sari, AD; Suryoputro, MR; Rahmillah, FI

2017-12-01

This article discusses 6S implementation in Ergonomic Laboratory, Department of Industrial Engineering, Islamic University of Indonesia. This research is improvement project of 5S implementation in Ergonomic laboratory. Referring to the 5S implementation of the previous year, there have been improvements from environmental conditions or a more organized workplace however there is still a lack of safety aspects. There are several safeties problems such as equipment arrangement, potential hazards of room dividers that cause injury several times, placement of fire extinguisher, no evacuation path and assembly point in case of fire, as well as expired hydrant condition and lack of awareness of stakeholders related to safety. Therefore, this study aims to apply the 6S kaizen method to the Ergonomic laboratory to facilitate the work process, reduce waste, improve work safety and improve staff performance. Based on the score 6S assessment increased audit results by 32 points, before implementation is 75 point while after implementation is 107 point. This has implications for better use for mitigate people in laboratory area, save time when looking for tools and materials, safe workplace, as well as improving the culture and spirit of ‘6S’ on staff due to better and safetier working environment.

Urine culture contamination: a College of American Pathologists Q-Probes study of 127 laboratories.

PubMed

Bekeris, Leonas G; Jones, Bruce Allen; Walsh, Molly K; Wagar, Elizabeth A

2008-06-01

While urine culture contamination may not be completely avoidable, some laboratories have lower contamination rates than others. A College of American Pathologists (CAP) 1998 Q-Probes study showed that many interventions commonly assumed to reduce contamination were not demonstrably effective. This article revisits the issue. To examine the frequency of urine culture contamination, review current laboratory practices in the collection of urine culture specimens, and determine practice characteristics that may be associated with the contamination rate. Laboratories participating in a CAP Q-Probes study were required to prospectively collect data on 120 consecutive urine culture specimens and provide information on the patient's demographics (age and sex), the location where the specimen was collected, how the specimen was handled, the number of isolates in quantities greater than or equal to 10,000 colony-forming units (CFU)/mL, and whether the laboratory considered the specimen to be contaminated. Specific inclusion and exclusion criteria were provided to the participants. Each laboratory completed a supplemental questionnaire that probed for specific laboratory urine culture collection practices. One hundred twenty-seven laboratories participated in the study. Results from a total of 14,739 urine specimens were received. For the purpose of this study, a urine specimen was determined to be contaminated if the culture yielded more than 2 isolates in quantities greater than or equal to 10,000 CFU/mL. Using these criteria the median institution had a contamination rate of 15.0%. Laboratories in the 10th percentile (low performance) had an average contamination rate of 41.7%, while laboratories in the 90th percentile had an average rate of 0.8%. The collection site had no influence on the contamination rate, but postcollection processing, especially refrigeration of the specimen, had a substantial effect. Providing instruction to patients produced a statistically

GeoBrain Computational Cyber-laboratory for Earth Science Studies

NASA Astrophysics Data System (ADS)

Deng, M.; di, L.

2009-12-01

Computational approaches (e.g., computer-based data visualization, analysis and modeling) are critical for conducting increasingly data-intensive Earth science (ES) studies to understand functions and changes of the Earth system. However, currently Earth scientists, educators, and students have met two major barriers that prevent them from being effectively using computational approaches in their learning, research and application activities. The two barriers are: 1) difficulties in finding, obtaining, and using multi-source ES data; and 2) lack of analytic functions and computing resources (e.g., analysis software, computing models, and high performance computing systems) to analyze the data. Taking advantages of recent advances in cyberinfrastructure, Web service, and geospatial interoperability technologies, GeoBrain, a project funded by NASA, has developed a prototype computational cyber-laboratory to effectively remove the two barriers. The cyber-laboratory makes ES data and computational resources at large organizations in distributed locations available to and easily usable by the Earth science community through 1) enabling seamless discovery, access and retrieval of distributed data, 2) federating and enhancing data discovery with a catalogue federation service and a semantically-augmented catalogue service, 3) customizing data access and retrieval at user request with interoperable, personalized, and on-demand data access and services, 4) automating or semi-automating multi-source geospatial data integration, 5) developing a large number of analytic functions as value-added, interoperable, and dynamically chainable geospatial Web services and deploying them in high-performance computing facilities, 6) enabling the online geospatial process modeling and execution, and 7) building a user-friendly extensible web portal for users to access the cyber-laboratory resources. Users can interactively discover the needed data and perform on-demand data analysis and

Atmospheric cloud physics laboratory project study

NASA Technical Reports Server (NTRS)

Schultz, W. E.; Stephen, L. A.; Usher, L. H.

1976-01-01

Engineering studies were performed for the Zero-G Cloud Physics Experiment liquid cooling and air pressure control systems. A total of four concepts for the liquid cooling system was evaluated, two of which were found to closely approach the systems requirements. Thermal insulation requirements, system hardware, and control sensor locations were established. The reservoir sizes and initial temperatures were defined as well as system power requirements. In the study of the pressure control system, fluid analyses by the Atmospheric Cloud Physics Laboratory were performed to determine flow characteristics of various orifice sizes, vacuum pump adequacy, and control systems performance. System parameters predicted in these analyses as a function of time include the following for various orifice sizes: (1) chamber and vacuum pump mass flow rates, (2) the number of valve openings or closures, (3) the maximum cloud chamber pressure deviation from the allowable, and (4) cloud chamber and accumulator pressure.

Laboratory studies of the interaction of ions with condensed gases: Planetary applications

NASA Technical Reports Server (NTRS)

Boring, J. W.; Johnson, R. E.

1990-01-01

The work described is concerned with laboratory studies of the processes that produce the ejection of molecules from the surfaces of condensed gas solids, the change in the chemistry of the surface materials, and the relationship of these results to processes occurring in the solar system. Included is a discussion of the experimental techniques employed in making these laboratory measurements.

Rhizosphere effect of colonizer plant species on the development of soil microbial community during primary succession on postmining sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elhottova, D.; Kristufek, V.; Maly, S.

2009-07-01

The impact of pioneer plant species Tussilago farfara on structural, functional, and growth characterization of microbial community colonizing the spoil colliery substrate was studied in a laboratory microcosm experiment. Microcosms consisting of spoil substrate (0.7 dm{sup 3} of tertiary alkaline clay sediment from Sokolov brown-coal mine area) from a pioneer site (without vegetation, 5 years after heaping) were cultivated in a greenhouse with one plant of this species. Plant roots substantially increased microbial diversity and biomass after one season (7 months) of cultivation. Roots influenced the microbial community and had nearly twice the size, higher growth, and metabolic potential inmore » comparison to the control. The development of microbial specialists improves the plant nutrient status. Bacterial nitrogen (N{sub 2}) fixators (Bradyrhizobium japonicum, Rhizobium radiobacter) and arbuscular mycorrhizal fungi were confirmed in the rhizosphere of Tussilago farfara.« less

Comparison of microbiological diagnosis of urinary tract infection in young children by routine health service laboratories and a research laboratory: Diagnostic cohort study.

PubMed

Birnie, Kate; Hay, Alastair D; Wootton, Mandy; Howe, Robin; MacGowan, Alasdair; Whiting, Penny; Lawton, Michael; Delaney, Brendan; Downing, Harriet; Dudley, Jan; Hollingworth, William; Lisles, Catherine; Little, Paul; O'Brien, Kathryn; Pickles, Timothy; Rumsby, Kate; Thomas-Jones, Emma; Van der Voort, Judith; Waldron, Cherry-Ann; Harman, Kim; Hood, Kerenza; Butler, Christopher C; Sterne, Jonathan A C

2017-01-01

To compare the validity of diagnosis of urinary tract infection (UTI) through urine culture between samples processed in routine health service laboratories and those processed in a research laboratory. We conducted a prospective diagnostic cohort study in 4808 acutely ill children aged <5 years attending UK primary health care. UTI, defined as pure/predominant growth ≥105 CFU/mL of a uropathogen (the reference standard), was diagnosed at routine health service laboratories and a central research laboratory by culture of urine samples. We calculated areas under the receiver-operator curve (AUC) for UTI predicted by pre-specified symptoms, signs and dipstick test results (the "index test"), separately according to whether samples were obtained by clean catch or nappy (diaper) pads. 251 (5.2%) and 88 (1.8%) children were classified as UTI positive by health service and research laboratories respectively. Agreement between laboratories was moderate (kappa = 0.36; 95% confidence interval [CI] 0.29, 0.43), and better for clean catch (0.54; 0.45, 0.63) than nappy pad samples (0.20; 0.12, 0.28). In clean catch samples, the AUC was lower for health service laboratories (AUC = 0.75; 95% CI 0.69, 0.80) than the research laboratory (0.86; 0.79, 0.92). Values of AUC were lower in nappy pad samples (0.65 [0.61, 0.70] and 0.79 [0.70, 0.88] for health service and research laboratory positivity, respectively) than clean catch samples. The agreement of microbiological diagnosis of UTI comparing routine health service laboratories with a research laboratory was moderate for clean catch samples and poor for nappy pad samples and reliability is lower for nappy pad than for clean catch samples. Positive results from the research laboratory appear more likely to reflect real UTIs than those from routine health service laboratories, many of which (particularly from nappy pad samples) could be due to contamination. Health service laboratories should consider adopting procedures used in

Comparison of microbiological diagnosis of urinary tract infection in young children by routine health service laboratories and a research laboratory: Diagnostic cohort study

PubMed Central

Birnie, Kate; Hay, Alastair D.; Wootton, Mandy; Howe, Robin; MacGowan, Alasdair; Whiting, Penny; Lawton, Michael; Delaney, Brendan; Downing, Harriet; Dudley, Jan; Hollingworth, William; Lisles, Catherine; Little, Paul; O’Brien, Kathryn; Pickles, Timothy; Rumsby, Kate; Thomas-Jones, Emma; Van der Voort, Judith; Waldron, Cherry-Ann; Harman, Kim; Hood, Kerenza; Butler, Christopher C.; Sterne, Jonathan A. C.

2017-01-01

Objectives To compare the validity of diagnosis of urinary tract infection (UTI) through urine culture between samples processed in routine health service laboratories and those processed in a research laboratory. Population and methods We conducted a prospective diagnostic cohort study in 4808 acutely ill children aged <5 years attending UK primary health care. UTI, defined as pure/predominant growth ≥105 CFU/mL of a uropathogen (the reference standard), was diagnosed at routine health service laboratories and a central research laboratory by culture of urine samples. We calculated areas under the receiver-operator curve (AUC) for UTI predicted by pre-specified symptoms, signs and dipstick test results (the “index test”), separately according to whether samples were obtained by clean catch or nappy (diaper) pads. Results 251 (5.2%) and 88 (1.8%) children were classified as UTI positive by health service and research laboratories respectively. Agreement between laboratories was moderate (kappa = 0.36; 95% confidence interval [CI] 0.29, 0.43), and better for clean catch (0.54; 0.45, 0.63) than nappy pad samples (0.20; 0.12, 0.28). In clean catch samples, the AUC was lower for health service laboratories (AUC = 0.75; 95% CI 0.69, 0.80) than the research laboratory (0.86; 0.79, 0.92). Values of AUC were lower in nappy pad samples (0.65 [0.61, 0.70] and 0.79 [0.70, 0.88] for health service and research laboratory positivity, respectively) than clean catch samples. Conclusions The agreement of microbiological diagnosis of UTI comparing routine health service laboratories with a research laboratory was moderate for clean catch samples and poor for nappy pad samples and reliability is lower for nappy pad than for clean catch samples. Positive results from the research laboratory appear more likely to reflect real UTIs than those from routine health service laboratories, many of which (particularly from nappy pad samples) could be due to contamination. Health service

Metabolic adaptation and in situ attenuation of chlorinated ethenes by naturally occurring microorganisms in a fractured dolomite aquifer near Niagara Falls, New York

USGS Publications Warehouse

Yager, R.M.; Bilotta, S.E.; Mann, C.L.; Madsen, E.L.

1997-01-01

A combination of hydrogeological, geochemical, and microbiological methods was used to document the biotransformation of trichloroethene (TCE) to ethene, a completely dechlorinated and environmentally benign compound, by naturally occurring microorganisms within a fractured dolomite aquifer. Analyses of groundwater samples showed that three microbially produced TCE breakdown products (cis-1,2-dichloroethene, vinyl chloride, and ethene) were present in the contaminant plume. Hydrogen (H2) concentrations in groundwater indicated that iron reduction was the predominant terminal electron-accepting process in the most contaminated geologic zone of the site. Laboratory microcosms prepared with groundwater demonstrated complete sequential dechlorination of TCE to ethene. Microcosm assays also revealed that reductive dechlorination activity was present in waters from the center but not from the periphery of the contaminant plume. This dechlorination activity indicated that naturally occurring microorganisms have adapted to utilize chlorinated ethenes and suggested that dehalorespiring rather than cometabolic, microbial processes were the cause of the dechlorination. The addition of pulverized dolomite to microcosms enhanced the rate of reductive dechlorination, suggesting that hydrocarbons in the dolomite aquifer may serve as electron donors to drive microbially mediated reductive dechlorination reactions. Biodegradation of the chlorinated ethenes appears to contribute significantly to decontamination of the site.A combination of hydrogeological, geochemical, and microbiological methods was used to document the biotransformation of trichloroethene (TCE) to ethene, a completely dechlorinated and environmentally benign compound, by naturally occurring microorganisms within a fractured dolomite aquifer. Analyses of groundwater samples showed that three microbially produced TCE breakdown products (cis-1,2-dichloroethene, vinyl chloride, and ethene) were present in the

Productivity of Veterans Health Administration laboratories: a College of American Pathologists Laboratory Management Index Program (LMIP) study.

PubMed

Valenstein, Paul N; Wang, Edward; O'Donohue, Tom

2003-12-01

The Veterans Health Administration (VA) operates the largest integrated laboratory network in the United States. To assess whether the unique characteristics of VA laboratories impact efficiency of operations, we compared the productivity of VA and non-VA facilities. Financial and activity data were prospectively collected from 124 VA and 131 non-VA laboratories enrolled in the College of American Pathologists Laboratory Management Index Program (LMIP) during 2002. In addition, secular trends in 5 productivity ratios were calculated for VA and non-VA laboratories enrolled in LMIP from 1997 through 2002. Veterans Health Administration and non-VA facilities did not differ significantly in size. Inpatients accounted for a lower percentage of testing at VA facilities than non-VA facilities (21.7% vs 37.3%; P <.001). Technical staff at the median VA facility were paid more than at non-VA facilities (28.11/h dollars vs 22.60/h dollars, salaries plus benefits; P <.001), VA laboratories employed a smaller percentage of nontechnical staff (30.0% vs 41.9%; P <.001), and workers at VA laboratories worked less time per hour paid (85.5% vs 88.5%; P <.001). However, labor productivity was significantly higher at VA than at non-VA facilities (30 448 test results/total full-time equivalent (FTE)/y vs 19 260 results/total FTE; P <.001), resulting in lower labor expense per on-site test at VA sites than at non-VA sites (1.79 dollars/result vs 2.08 dollars/result; P <.001). Veterans Health Administration laboratories paid less per test for consumables (P =.003), depreciation, and maintenance than their non-VA counterparts (all P <.001), resulting in lower overall cost per on-site test result (2.64 dollars vs 3.40 dollars; P <.001). Cost per referred (sent-out) test did not differ significantly between the 2 groups. Analysis of 6-year trends showed significant increases in both VA (P <.001) and non-VA (P =.02) labor productivity (on-site tests/total FTE). Expenses at VA laboratories

Virtual Laboratory "vs." Traditional Laboratory: Which Is More Effective for Teaching Electrochemistry?

ERIC Educational Resources Information Center

Hawkins, Ian; Phelps, Amy J.

2013-01-01

The use of virtual laboratories has become an increasing issue regarding science laboratories due to the increasing cost of hands-on laboratories, and the increase in distance education. Recent studies have looked at the use of virtual tools for laboratory to be used as supplements to the regular hands-on laboratories but many virtual tools have…

Impact of pyrene and cadmium co-contamination on prokaryotic community in coastal sediment microcosms.

PubMed

Ding, Qifang; Huang, Xiaolin; Hu, Hanjing; Hong, Man; Zhang, Demin; Wang, Kai

2017-12-01

Acute ecological impacts of co-contamination of polycyclic aromatic hydrocarbons (PAHs) and heavy metals on diversity and composition of coastal benthic prokaryotes were unclear. We took pyrene (Pyr) and cadmium (Cd) as the representatives and mimicked an eight-week exposure of moderate and high levels of Pyr, Cd and their mixtures. 16S rRNA amplicon sequencing was used to investigate interaction of the contaminants in temporal succession of prokaryotes. Generally, concentrations of Pyr and HCl-extractable Cd in the sediments were stable over time. Effects and interaction of Pyr and Cd on prokaryotic α-diversity were temporally- and dose-dependent with a decreasing trend in richness and Shannon index under various contamination regimes, particularly in the single-Cd contaminated groups at the early stage. Temporal variability and Pyr-induced pattern in prokaryotic composition were observed. However, Pyr and Cd showed a persistent interaction in prokaryotic composition after 7 days, altering successional trajectories of communities. The communities under Pyr contamination regardless of Cd could be at a developing stage for an active PAH-degrading community with appearance of a pioneer Cycloclasticus phylotype, persistently showing a strong correlation with Pyr level. The associations of phylotypes and Cd level were short-lived and weak, corresponding to the overall resistance of prokaryotic composition to Cd. In the high-throughput sequencing era, using microcosm experiment, we renewed the knowledge about how prokaryotes vary in terms of α-diversity, composition and specific taxa in response to co-contamination of model contaminants at a temporal scale. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biogeochemical modeling of CO2 and CH4 production in anoxic Arctic soil microcosms

NASA Astrophysics Data System (ADS)

Tang, Guoping; Zheng, Jianqiu; Xu, Xiaofeng; Yang, Ziming; Graham, David E.; Gu, Baohua; Painter, Scott L.; Thornton, Peter E.

2016-09-01

Soil organic carbon turnover to CO2 and CH4 is sensitive to soil redox potential and pH conditions. However, land surface models do not consider redox and pH in the aqueous phase explicitly, thereby limiting their use for making predictions in anoxic environments. Using recent data from incubations of Arctic soils, we extend the Community Land Model with coupled carbon and nitrogen (CLM-CN) decomposition cascade to include simple organic substrate turnover, fermentation, Fe(III) reduction, and methanogenesis reactions, and assess the efficacy of various temperature and pH response functions. Incorporating the Windermere Humic Aqueous Model (WHAM) enables us to approximately describe the observed pH evolution without additional parameterization. Although Fe(III) reduction is normally assumed to compete with methanogenesis, the model predicts that Fe(III) reduction raises the pH from acidic to neutral, thereby reducing environmental stress to methanogens and accelerating methane production when substrates are not limiting. The equilibrium speciation predicts a substantial increase in CO2 solubility as pH increases, and taking into account CO2 adsorption to surface sites of metal oxides further decreases the predicted headspace gas-phase fraction at low pH. Without adequate representation of these speciation reactions, as well as the impacts of pH, temperature, and pressure, the CO2 production from closed microcosms can be substantially underestimated based on headspace CO2 measurements only. Our results demonstrate the efficacy of geochemical models for simulating soil biogeochemistry and provide predictive understanding and mechanistic representations that can be incorporated into land surface models to improve climate predictions.

Laboratory experiments in the study of the chemistry of the outer planets.

PubMed

Scattergood, T W

1987-01-01

The investigation of chemical evolution of bodies in our solar system has, in the past, included observations, theoretical modeling, and laboratory simulations. Of these programs, the last one has been the most criticized due to the inherent difficulties in accurately recreating alien environments in the laboratory. Processes such as wall reactions and changes in chemistry due to difficulties in achieving realistic conditions of temperature, pressure, composition, and energy flux may yield results which are not truly representative of the systems being modeled. However, many laboratory studies have been done which have yielded data useful in planetary science. Gross simulations of atmospheric chemistry have placed constraints on the nature of complex molecules expected in planetary atmospheres. More precise studies of specific chemical processes have provided information about the sources and properties of product gases and aerosols. Determinations of basic properties such as spectral features and reaction rate constants yield data useful in the interpretation of observations and in computational modeling. Alone, and in conjunction with modeling, laboratory experiments will continue to be used to further our understanding of the outer solar system, and some experiments that need to be done are listed.

Laboratory Needs for Interstellar Ice Studies

NASA Astrophysics Data System (ADS)

Boogert, Abraham C. A.

2012-05-01

A large fraction of the molecules in dense interstellar and circumstellar environments is stored in icy grain mantles. The mantles are formed by a complex interplay between chemical and physical processes. Key questions on the accretion and desorption processes and the chemistry on the grain surfaces and within the icy mantles can only be answered by laboratory experiments. Recent infrared (2-30 micron) spectroscopic surveys of large samples of Young Stellar Objects (YSOs) and background stars tracing quiescent cloud material have shown that the ice band profiles and depths vary considerably as a function of environment. Using laboratory spectra in the identification process, it is clear that a rather complex mixture of simple species (CH3OH, CO2, H2O, CO) exists even in the quiescent cloud phase. Variations of the local physical conditions (CO freeze out) and time scales (CH3OH formation) appear to be key factors in the observed variations. Sublimation and thermal processing dominate as YSOs heat their environments. The identification of several ice absorption features is still disputed. I will outline laboratory work (e.g., on salts, PAHs, and aliphatic hydrocarbons) needed to further constrain the ice band identification as well as the thermal and chemical history of the carriers. Such experiments will also be essential to interpret future high spectral resolution SOFIA and JWST observations.

Can the algicidal material Ca-aminoclay be harmful when applied to a natural ecosystem? An assessment using microcosms.

PubMed

Jung, Seung Won; Yun, Suk Min; Yoo, Jae Won; Zhun, Li; Jang, Pung-Guk; Lim, Dhong-Il; Lee, Young-Chul; Lee, Hyun Uk; Lee, Taek-Kyun; Heo, Jinbee; Lee, Jin Hwan; Han, Myung-Soo

2015-11-15

We assessed the ability of an artificial clay (Ca-aminoclay) to suppress harmful algal bloom species (HABs) such as Cochlodinium polykrikoides and Chattonella marina and investigated the ecological responses in the closed and open microcosm systems. The Ca-aminoclay induced rapidly and selectively cell lysis in the HABs. However, applying Ca-aminoclay could cause adverse impacts in terms of biological and environmental changes. The bacterioplankton abundance increased and then, the abundances of heterotrophic nanoflagellates and ciliates increased rapidly. Extremely poor environmental conditions such as increase in nutrients and development of anoxic conditions were sustained continuously in a closed system, while the environmental conditions in open systems deteriorated before recovering to the initial conditions. We evaluated the potential for the occurrence of a bloom of another phytoplankton after HABs had been controlled using the Ca-aminoclay. The Ca-aminoclay controlled blooms of Chattonella marina in mixed cell cultures containing a Tetraselmis chui. However, T. chui increased over time and then bloomed. Therefore, caution should be taken when considering the direct application of Ca-aminoclay in natural environments even though it offers the rapid removal of HABs. Copyright © 2015 Elsevier B.V. All rights reserved.

Exploring the links between quality assurance and laboratory resources. An audit-based study.

PubMed

Singh, Navjeevan; Panwar, Aru; Masih, Vipin Fazal; Arora, Vinod K; Bhatia, Arati

2003-01-01

To investigate and rectify the problems related to Ziehl-Neelsen (Z-N) staining in a cytology laboratory in the context of quality assurance. An audit based quality assurance study of 1,421 patients with clinical diagnoses of tubercular lymphadenopathy who underwent fine needle aspiration cytology. Data from 8 months were audited (group 1). Laboratory practices related to selection of smears for Z-N staining were studied. A 2-step corrective measure based on results of the audit was introduced for 2 months (group 2). Results were subjected to statistical analysis using the chi 2 test. Of 1,172 patients in group 1,368 had diagnoses other than tuberculosis. Overall acid-fast bacillus (AFB) positivity was 42%. AFB positivity in 249 patients in group 2 was 89% (P < .0001). Several issues in the laboratory are linked to quality assurance. Solving everyday problems can have far-reaching benefits for the performance of laboratory personnel, resources and work flow.

How do laboratory technicians perceive their role in the tuberculosis diagnostic process? A cross-sectional study among laboratory technicians in health centers of Central Java Province, Indonesia.

PubMed

Widjanarko, Bagoes; Widyastari, Dyah Anantalia; Martini, Martini; Ginandjar, Praba

2016-01-01

Detection of acid-fast bacilli in respiratory specimens serves as an initial pulmonary tuberculosis (TB) diagnosis. Laboratories are the essential and fundamental part of all health systems. This study aimed to describe how laboratory technicians perceived their own self and work. This included perceived self-efficacy, perceived role, perceived equipment availability, perceived procedures, perceived reward and job, and perceived benefit of health education, as well as level of knowledge and attitudes related to work performance of laboratory technicians. This was a cross-sectional quantitative study involving 120 laboratory technicians conducted in Central Java. Interviews and observation were conducted to measure performance and work-related variables. Among 120 laboratory technicians, 43.3% showed fairly good performance. They complied with 50%-75% of all procedures, including sputum collection, laboratory tools utilization, sputum smearing, staining, smear examination, grading of results, and universal precaution practice. Perceived role, perceived self-efficacy, and knowledge of laboratory procedures were significantly correlated to performance, besides education and years of working as a laboratory technician. Perceived equipment availability was also significantly correlated to performance after the education variable was controlled. Most of the laboratory technicians believed that they have an important role in TB patients' treatment and should display proper self-efficacy in performing laboratory activities. The result may serve as a basic consideration to develop a policy for enhancing motivation of laboratory technicians in order to improve the TB control program.

How do laboratory technicians perceive their role in the tuberculosis diagnostic process? A cross-sectional study among laboratory technicians in health centers of Central Java Province, Indonesia

PubMed Central

Widjanarko, Bagoes; Widyastari, Dyah Anantalia; Martini, Martini; Ginandjar, Praba

2016-01-01

Purpose Detection of acid-fast bacilli in respiratory specimens serves as an initial pulmonary tuberculosis (TB) diagnosis. Laboratories are the essential and fundamental part of all health systems. This study aimed to describe how laboratory technicians perceived their own self and work. This included perceived self-efficacy, perceived role, perceived equipment availability, perceived procedures, perceived reward and job, and perceived benefit of health education, as well as level of knowledge and attitudes related to work performance of laboratory technicians. Methods This was a cross-sectional quantitative study involving 120 laboratory technicians conducted in Central Java. Interviews and observation were conducted to measure performance and work-related variables. Results Among 120 laboratory technicians, 43.3% showed fairly good performance. They complied with 50%–75% of all procedures, including sputum collection, laboratory tools utilization, sputum smearing, staining, smear examination, grading of results, and universal precaution practice. Perceived role, perceived self-efficacy, and knowledge of laboratory procedures were significantly correlated to performance, besides education and years of working as a laboratory technician. Perceived equipment availability was also significantly correlated to performance after the education variable was controlled. Conclusion Most of the laboratory technicians believed that they have an important role in TB patients’ treatment and should display proper self-efficacy in performing laboratory activities. The result may serve as a basic consideration to develop a policy for enhancing motivation of laboratory technicians in order to improve the TB control program. PMID:27660502

Short-term changes in the composition of active marine bacterial assemblages in response to diesel oil pollution.

PubMed

Lanfranconi, Mariana P; Bosch, Rafael; Nogales, Balbina

2010-09-01

The changes caused by diesel oil pollution in the metabolically active bacterioplankton from an oligotrophic coastal location were analysed in laboratory microcosms (44 l) using 16S ribosomal RNA (16S rRNA) as molecular marker. The aim was to simulate typical hydrocarbon pollution events in a coastal area exploited for seasonal touristic activities. The experiment consisted in addition of low amounts of diesel oil without nutrients to seawater collected at different times (winter and summer). Bacterial diversity was analysed by terminal-restriction fragment length polymorphism (T-RFLP) profiling of 16S rRNAs after reverse transcription polymerase chain reaction (RT-PCR), and by generation of 16S rRNA clone libraries in control and diesel-polluted microcosms. Diesel addition caused a twofold increase in prokaryotic numbers in comparison with controls at the end of the experiment, both in winter and summer microcosms. Bacterioplankton composition, determined by 16S rRNA T-RFLP data, changed rapidly (within 17 h) in response to treatment. The resulting communities were different in microcosms with water collected in summer and winter. A reduction in diversity (Shannon index, calculated on the basis of T-RFLP data) was observed only in summer microcosms. This was due to the rapid increase of phylotypes affiliated to the Oceanospirillaceae, not observed in winter microcosms. After diesel treatment there was a reduction in the number of phylotypes related to SAR11, SAR86 and picocyanobacteria, while phylotypes of the Roseobacter clade, and the OMG group seemed to be favoured. Our results show that diesel pollution alone caused profound effects on the bacterioplankton of oligotrophic seawater, and explained many of the differences in diversity reported previously in pristine and polluted sites in this coastal area. © 2010 The Authors; Journal compilation © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.

Development of performance properties of ternary mixtures : laboratory study on concrete.

DOT National Transportation Integrated Search

2011-03-01

This research project is a comprehensive study of how supplementary cementitious materials (SCMs) can be used to : improve the performance of concrete mixtures. This report summarizes the findings of the Laboratory Study on Concrete : phase of this w...

Transferability and within- and between-laboratory reproducibilities of EpiSensA for predicting skin sensitization potential in vitro: A ring study in three laboratories.

PubMed

Mizumachi, Hideyuki; Sakuma, Megumi; Ikezumi, Mayu; Saito, Kazutoshi; Takeyoshi, Midori; Imai, Noriyasu; Okutomi, Hiroko; Umetsu, Asami; Motohashi, Hiroko; Watanabe, Mika; Miyazawa, Masaaki

2018-05-03

The epidermal sensitization assay (EpiSensA) is an in vitro skin sensitization test method based on gene expression of four markers related to the induction of skin sensitization; the assay uses commercially available reconstructed human epidermis. EpiSensA has exhibited an accuracy of 90% for 72 chemicals, including lipophilic chemicals and pre-/pro-haptens, when compared with the results of the murine local lymph node assay. In this work, a ring study was performed by one lead and two naive laboratories to evaluate the transferability, as well as within- and between-laboratory reproducibilities, of EpiSensA. Three non-coded chemicals (two lipophilic sensitizers and one non-sensitizer) were tested for the assessment of transferability and 10 coded chemicals (seven sensitizers and three non-sensitizers, including four lipophilic chemicals) were tested for the assessment of reproducibility. In the transferability phase, the non-coded chemicals (two sensitizers and one non-sensitizer) were correctly classified at the two naive laboratories, indicating that the EpiSensA protocol was transferred successfully. For the within-laboratory reproducibility, the data generated with three coded chemicals tested in three independent experiments in each laboratory gave consistent predictions within laboratories. For the between-laboratory reproducibility, 9 of the 10 coded chemicals tested once in each laboratory provided consistent predictions among the three laboratories. These results suggested that EpiSensA has good transferability, as well as within- and between-laboratory reproducibility. Copyright © 2018 John Wiley & Sons, Ltd.

Laboratory studies of cometary ice analogues

NASA Astrophysics Data System (ADS)

Schmitt, B.; Espinasse, S.; Grim, R. J. A.; Greenberg, J. M.; Klinger, J.

1989-12-01

Laboratory studies were performed in order to simulate the physico-chemical processes that are likely to occur in the near surface layers of short and intermediate period comets. Pure H2O ice as well as CO:H2O, CO2:H2O, CH4:H2O, CO:CO2:H2O, and NH3:H2O ice mixtures were studied in the temperature range between 10 and 180 K. The evolution of the composition of ice mixtures, the crystallization of H2O ice as well as the formation and decompostion of clathrate hydrate by different processes were studied as a function of temperature and time. Using the results together with numerical modeling, predictions are made about the survival of amorphous ice, CO, CO2, CH4, and NH3 in the near surface layers of short period comets. The likeliness of finding clathrate and molecular hydrates is discussed. It is proposed that the analytical methods developed here could be fruitfully adapted to the analysis of returned comet samples.

A Feasibility Study for Mobile Marketing and Distribution Occupational Laboratories in North Dakota.

ERIC Educational Resources Information Center

Kohns, Donald P.

A study determined the feasibility of a mobile laboratory for marketing and distribution in North Dakota. It attempted to answer four questions: (1) What types of staffing, equipment, curriculum, and delivery systems are presently being utilized in mobile laboratories throughout the nation? (2) What significant information obtained from mobile…

Sediment laboratory quality-assurance project: studies of methods and materials

USGS Publications Warehouse

Gordon, J.D.; Newland, C.A.; Gray, J.R.

2001-01-01

In August 1996 the U.S. Geological Survey initiated the Sediment Laboratory Quality-Assurance project. The Sediment Laboratory Quality Assurance project is part of the National Sediment Laboratory Quality-Assurance program. This paper addresses the fmdings of the sand/fme separation analysis completed for the single-blind reference sediment-sample project and differences in reported results between two different analytical procedures. From the results it is evident that an incomplete separation of fme- and sand-size material commonly occurs resulting in the classification of some of the fme-size material as sand-size material. Electron microscopy analysis supported the hypothesis that the negative bias for fme-size material and the positive bias for sand-size material is largely due to aggregation of some of the fine-size material into sand-size particles and adherence of fine-size material to the sand-size grains. Electron microscopy analysis showed that preserved river water, which was low in dissolved solids, specific conductance, and neutral pH, showed less aggregation and adhesion than preserved river water that was higher in dissolved solids and specific conductance with a basic pH. Bacteria were also found growing in the matrix, which may enhance fme-size material aggregation through their adhesive properties. Differences between sediment-analysis methods were also investigated as pan of this study. Suspended-sediment concentration results obtained from one participating laboratory that used a total-suspended solids (TSS) method had greater variability and larger negative biases than results obtained when this laboratory used a suspended-sediment concentration method. When TSS methods were used to analyze the reference samples, the median suspended sediment concentration percent difference was -18.04 percent. When the laboratory used a suspended-sediment concentration method, the median suspended-sediment concentration percent difference was -2

[Comparability study of analytical results between a group of clinical laboratories].

PubMed

Alsius-Serra, A; Ballbé-Anglada, M; López-Yeste, M L; Buxeda-Figuerola, M; Guillén-Campuzano, E; Juan-Pereira, L; Colomé-Mallolas, C; Caballé-Martín, I

2015-01-01

To describe the study of the comparability of the measurements levels of biological tests processed in biochemistry in Catlab's 4 laboratories. Quality requirements, coefficients of variation and total error (CV% and TE %) were established. Controls were verified with the precision requirements (CV%) in each test and each individual laboratory analyser. Fresh serum samples were used for the comparability study. The differences were analysed using a Microsoft Access® application that produces modified Bland-Altman plots. The comparison of 32 biological parameters that are performed in more than one laboratory and/or analyser generated 306 Bland-Altman graphs. Of these, 101 (33.1%) fell within the accepted range of values based on biological variability, and 205 (66.9%) required revision. Data were re-analysed based on consensus minimum specifications for analytical quality (consensus of the Asociación Española de Farmacéuticos Analistas (AEFA), the Sociedad Española de Bioquímica Clínica y Patología Molecular (SEQC), the Asociación Española de Biopatología Médica (AEBM) and the Sociedad Española de Hematología y Hemoterapia (SEHH), October 2013). With the new specifications, 170 comparisons (56%) fitted the requirements and 136 (44%) required additional review. Taking into account the number of points that exceeded the requirement, random errors, range of results in which discrepancies were detected, and range of clinical decision, it was shown that the 44% that required review were acceptable, and the 32 tests were comparable in all laboratories and analysers. The analysis of the results showed that the consensus requirements of the 4 scientific societies were met. However, each laboratory should aim to meet stricter criteria for total error. Copyright © 2015 SECA. Published by Elsevier Espana. All rights reserved.

Laboratory studies with the systemic trichononacide, metronidazole

PubMed Central

Jennison, R. F.; Stenton, P.; Watt, Leslie

1961-01-01

Laboratory studies with the trichomonacidal agent, metronidazole, show that 66 strains of T. vaginalis were killed in three days by concentrations of 0·0625 μg./ml. to 1 μg./ml. Estimations of serum and urine levels in nine volunteers, the serum levels in 31 women, and the urine levels in 33 women show that metronidazole is rapidly absorbed and excreted in high concentration in the urine. Development of resistance to metronidazole by T. vaginalis has not been demonstrated either in vivo or in vitro. No toxic effect was demonstrated in the blood, liver, or kidney. PMID:13789871

The case for investigating social context in laboratory studies of smoking.

PubMed

Dimoff, John D; Sayette, Michael A

2017-03-01

With increasing frequency, addiction is conceived of as a brain disease, and such accounts seem especially pertinent with regard to the rapid delivery of nicotine to the brain via cigarette smoke. Moreover, drug administration trials (cigarette puffs) suggest that the behavior of smoking becomes automatized, with individuals developing prototypical approaches to smoking a cigarette. Compared with presumably more social activities, such as drinking alcohol, there may be little opportunity for social processes to influence smoking behavior. However, survey research examining smoking motivation often reveals a broadly defined 'social' factor and field research suggests that social context does influence smoking. We posit that laboratory smoking research has largely ignored social contextual factors that may help to understand better the precise mechanisms underlying smoking behavior and smoking motivation. We reviewed laboratory studies examining the effect of social context (operationalized as modeling) on smoking behavior. Studies were identified by searching PsychInfo and Medline using the following keywords: smoking, nicotine, tobacco, cigarette, consumption, topography, puff, smoking behavior, cigarettes smoked, modeling, imitation, social context, social influence and peer pressure. The reference and citation lists of these studies were then searched to identify additional studies. Few laboratory smoking studies target social context. Those few studies indicate that smoking behavior can be influenced by the presence of others. There is also some evidence that social context influences the effects of smoking as well as processes related to self-perception and self-regulation that reinforce smoking and hamper smoking cessation efforts. © 2016 Society for the Study of Addiction.

Detection of Cryptosporidium and Giardia in clinical laboratories in Europe--a comparative study.

PubMed

Manser, M; Granlund, M; Edwards, H; Saez, A; Petersen, E; Evengard, B; Chiodini, P

2014-01-01

To determine the routine diagnostic methods used and compare the performance in detection of oocysts of Cryptosporidium species and cysts of Giardia intestinalis in faecal samples by European specialist parasitology laboratories and European clinical laboratories. Two sets of seven formalin-preserved faecal samples, one containing cysts of Giardia intestinalis and the other, containing oocysts of Cryptosporidium, were sent to 18 laboratories. Participants were asked to examine the specimens using their routine protocol for detecting these parasites and state the method(s) used. Eighteen laboratories answered the questionnaire. For detection of Giardia, 16 of them used sedimentation/concentration followed by light microscopy. Using this technique the lower limit of detection of Giardia was 17.2 cysts/mL of faeces in the best performing laboratories. Only three of 16 laboratories used fluorescent-conjugated antibody-based microscopy. For detection of Cryptosporidium acid-fast staining was used by 14 of the 17 laboratories that examined the samples. With this technique the lower limit of detection was 976 oocysts/mL of faeces. Fluorescent-conjugated antibody-based microscopy was used by only five of the 17 laboratories. There was variation in the lower limit of detection of cysts of Giardia and oocysts of Cryptosporidium between laboratories using the same basic microscopic methods. Fluorescent-conjugated antibody-based microscopy was not superior to light microscopy under the conditions of this study. There is a need for a larger-scale multi-site comparison of the methods used for the diagnosis of these parasites and the development of a Europe-wide laboratory protocol based upon its findings. © 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.

Laboratory Study of Wave Generation Near Dipolarization Fronts

NASA Astrophysics Data System (ADS)

Tejero, E. M.; Enloe, C. L.; Amatucci, B.; Crabtree, C. E.; Ganguli, G.; Malaspina, D.

2017-12-01

Experiments conducted in the Space Physics Simulation Chamber at the Naval Research Laboratory (NRL) create plasma equilibria that replicate those found in dipolarization fronts. These experiments were designed to study the dynamics of boundary layers, such as dipolarization fronts, and it was found that there are instabilities generated by highly inhomogeneous plasma flows. It has previously been shown that these highly inhomogeneous flows can generate waves in the lower hybrid frequency range. Analysis of satellite observations indicate that the sheared flows are a plausible explanation for the observed lower hybrid waves at dipolarization fronts since they can generate longer wavelengths compared to the electron gyroradius, which is consistent with observations. Recent experiments at NRL have demonstrated that these flows can also generate electromagnetic waves in the whistler band. These waves are large amplitude, bursty waves that exhibit frequency chirps similar to whistler mode chorus. Recent results from these experiments and comparisons to in situ observations will be presented. * Work supported by the Naval Research Laboratory Base Program and NASA Grant No. NNH17AE70I.

Insights into environmental controls on microbial communities in a continental serpentinite aquifer using a microcosm-based approach

PubMed Central

Crespo-Medina, Melitza; Twing, Katrina I.; Kubo, Michael D. Y.; Hoehler, Tori M.; Cardace, Dawn; McCollom, Tom; Schrenk, Matthew O.

2014-01-01

Geochemical reactions associated with serpentinization alter the composition of dissolved organic compounds in circulating fluids and potentially liberate mantle-derived carbon and reducing power to support subsurface microbial communities. Previous studies have identified Betaproteobacteria from the order Burkholderiales and bacteria from the order Clostridiales as key components of the serpentinite–hosted microbiome, however there is limited knowledge of their metabolic capabilities or growth characteristics. In an effort to better characterize microbial communities, their metabolism, and factors limiting their activities, microcosm experiments were designed with fluids collected from several monitoring wells at the Coast Range Ophiolite Microbial Observatory (CROMO) in northern California during expeditions in March and August 2013. The incubations were initiated with a hydrogen atmosphere and a variety of carbon sources (carbon dioxide, methane, acetate, and formate), with and without the addition of nutrients and electron acceptors. Growth was monitored by direct microscopic counts; DNA yield and community composition was assessed at the end of the 3 month incubation. For the most part, results indicate that bacterial growth was favored by the addition of acetate and methane, and that the addition of nutrients and electron acceptors had no significant effect on microbial growth, suggesting no nutrient- or oxidant-limitation. However, the addition of sulfur amendments led to different community compositions. The dominant organisms at the end of the incubations were closely related to Dethiobacter sp. and to the family Comamonadaceae, which are also prominent in culture-independent gene sequencing surveys. These experiments provide one of first insights into the biogeochemical dynamics of the serpentinite subsurface environment and will facilitate experiments to trace microbial activities in serpentinizing ecosystems. PMID:25452748

Insights into environmental controls on microbial communities in a continental serpentinite aquifer using a microcosm-based approach.

PubMed

Crespo-Medina, Melitza; Twing, Katrina I; Kubo, Michael D Y; Hoehler, Tori M; Cardace, Dawn; McCollom, Tom; Schrenk, Matthew O

2014-01-01

Geochemical reactions associated with serpentinization alter the composition of dissolved organic compounds in circulating fluids and potentially liberate mantle-derived carbon and reducing power to support subsurface microbial communities. Previous studies have identified Betaproteobacteria from the order Burkholderiales and bacteria from the order Clostridiales as key components of the serpentinite-hosted microbiome, however there is limited knowledge of their metabolic capabilities or growth characteristics. In an effort to better characterize microbial communities, their metabolism, and factors limiting their activities, microcosm experiments were designed with fluids collected from several monitoring wells at the Coast Range Ophiolite Microbial Observatory (CROMO) in northern California during expeditions in March and August 2013. The incubations were initiated with a hydrogen atmosphere and a variety of carbon sources (carbon dioxide, methane, acetate, and formate), with and without the addition of nutrients and electron acceptors. Growth was monitored by direct microscopic counts; DNA yield and community composition was assessed at the end of the 3 month incubation. For the most part, results indicate that bacterial growth was favored by the addition of acetate and methane, and that the addition of nutrients and electron acceptors had no significant effect on microbial growth, suggesting no nutrient- or oxidant-limitation. However, the addition of sulfur amendments led to different community compositions. The dominant organisms at the end of the incubations were closely related to Dethiobacter sp. and to the family Comamonadaceae, which are also prominent in culture-independent gene sequencing surveys. These experiments provide one of first insights into the biogeochemical dynamics of the serpentinite subsurface environment and will facilitate experiments to trace microbial activities in serpentinizing ecosystems.

Microbial Community Shifts due to Hydrofracking: Observations from Field-Scale Observations and Laboratory-Scale Incubations

NASA Astrophysics Data System (ADS)

Mouser, P. J.; Ansari, M.; Hartsock, A.; Lui, S.; Lenhart, J.

2012-12-01

The use of fluids containing chemicals and variable water sources during the hydrofracking of unconventional shale is the source of considerable controversy due to perceived risks from altered subsurface biogeochemistry and the potential for contaminating potable water supplies. Rapid shifts in subsurface biogeochemistry are often driven by available macronutrients combined with the abundance and metabolic condition of the subsurface microbiota. While the depth that fracturing occurs in the Marcellus formation is reasonably deep to pose little risk to groundwater supplies, no published studies have systematically characterized the indigenous microbial population and how this community is altered through variable fluid management practices (e.g., chemical composition, source water makeup). In addition, limited information is available on how shallower microbial communities and geochemical conditions might be affected through the accidental release of these fluids to groundwater aquifers. Our measurements indicate field-applied and laboratory-generated fracking fluids contain levels of organic carbon greater than 300 mg/l and nitrogen concentrations greater than 80 mg/l that may differentially stimulate microbial growth in subsurface formations. In contrast to certain inorganic constituents (e.g., chloride) which increase in concentration through the flowback period; dissolved organic carbon levels decrease with time after the fracturing process through multiple attenuation processes (dilution, sorption, microbial utilization). Pyrosequencing data of the 16S rRNA gene indicate a shift from a more diverse source water microbial community to a less diverse community typical of a brine formation as time after fracturing increases. The introduction of varying percentages of a laboratory-generated fracking fluid to microcosm bottles containing groundwater and aquifer media stimulated biogeochemical changes similar to the introduction of landfill leachate, another

Midcontinent microcosm: Geology of the Atkins lake - Marengo falls area (Field trip 2)

USGS Publications Warehouse

Bjørnerud, Marcia; Cannon, William F.

2011-01-01

Archean and Proterozoic rocks exposed over about 16km2 between Atkins Lake and Coffee Lake in southeastern Bayfield County (Fig. 1) chronicle almost all of the major Precambrian geologic events in the history of the southern Superior Craton. The oldest rocks are part of a locally gneissic quartz monzonite complex, the Puritan Batholith, with an igneous Rb-Sr age of 2710+140 Ma (Sims et al., 1977). At the regional scale, this complex is part of one of the youngest Archean granite-greenstone belts in the Superior Province, and it intrudes greenstones of the Neoarchean Ramsay Formation. In the Atkins Lake – Marengo River area, the Puritan Batholith is nonconformably overlain by the Paleoproterozoic (ca. 2200 Ma) Bad River Dolomite. The Bad River Dolomite is in turn separated by an unconformity from rocks of the ca. 1875 Ma Menominee Group (Palms Formation and Ironwood Iron-formation), which locally contain mafic volcanic rocks and diabase sills (Cannon et al., 2008). These Paleoproterozoic rocks provide insight into climate and biogeochemical cycles during the transition to an oxidizing atmosphere (Bekker et al., 2006) and have deformational fabrics (folds, strong cleavage, local mylonite zones) that record the ca. 1850 Ma Penokean Orogeny. The youngest rocks in the area are Mesoproterozoic basaltic lava flows (Siemens Creek Volcanics, ca. 1110 Ma) and a layered mafic complex (the Mineral Lake Intrusion, also ca. 1100 Ma), both related to the Mid-continent Rift. All of the stratified units show static contact metamorphic textures near their contacts with the Mineral Lake Intrusion. Thus the area constitutes a microcosm of the regional bedrock geology, and the cross-cutting relationships among the units provide clear constraints on the relative timing of different phases of deformation and magmatism (Cannon etal., 2008, Bjørnerud, 2010a).

Laboratory study of spectral waves over a muddy bottom

NASA Astrophysics Data System (ADS)

Maxeiner, E.; Dalrymple, R. A.

2010-12-01

The attenuation of water waves propagating over a muddy ocean floor has been studied extensively both analytically and experimentally over the past 30 years. Possible mechanisms for this include surface wave interactions with the bottom, surface wave interactions with waves formed at the water/mud interface (lutocline) and shear instability at the water/mud interface. Typically these studies have focused on monochromatic waves. Observations of wave attenuation in the field, however, are subject to a spectrum of wave frequencies and sizes. A few field studies (Sheremet and Stone, 2003; Elgar and Raubenheimer, 2008) have explored the possible effects that a wide spectrum of wave frequencies may have on wave damping mechanisms. In this study, the wave attenuation exhibited by a sea spectrum over a muddy bottom is studied experimentally in a laboratory for the first time. Using an 18 m-long wave tank at the Coastal Engineering Laboratory at Johns Hopkins University, a piston-style wave maker is used to create both monochromatic and spectral waves. A 10 m-long section of the tank floor incorporates a recessed layer of kaolinite clay which subsequently mixes with the overlying water in the presence of waves. Testing consists of three phases. First, a series of monochromatic wave trains are produced over a range of wave frequencies and in a range of water depths to assess the damping behavior with respect to a variety of parameters such as wave frequency, wave height and water depth. Damping is assessed by comparing wave height at various longitudinal locations in the tank. Second, “wave beats” are created by superimposing waves of two frequencies to create a longer envelope. Third, the wave maker is used to generate a representative random sea condition, based on the Pierson-Moskowitz sea spectrum. For this type of testing, damping is assessed by measuring wave energy flux over a period of time at various longitudinal locations in the tank. Spectral analysis is also

Citrate and malonate increase microbial activity and alter microbial community composition in uncontaminated and diesel-contaminated soil microcosms

NASA Astrophysics Data System (ADS)

Martin, Belinda C.; George, Suman J.; Price, Charles A.; Shahsavari, Esmaeil; Ball, Andrew S.; Tibbett, Mark; Ryan, Megan H.

2016-09-01

Petroleum hydrocarbons (PHCs) are among the most prevalent sources of environmental contamination. It has been hypothesized that plant root exudation of low molecular weight organic acid anions (carboxylates) may aid degradation of PHCs by stimulating heterotrophic microbial activity. To test their potential implication for bioremediation, we applied two commonly exuded carboxylates (citrate and malonate) to uncontaminated and diesel-contaminated microcosms (10 000 mg kg-1; aged 40 days) and determined their impact on the microbial community and PHC degradation. Every 48 h for 18 days, soil received 5 µmol g-1 of (i) citrate, (ii) malonate, (iii) citrate + malonate or (iv) water. Microbial activity was measured daily as the flux of CO2. After 18 days, changes in the microbial community were assessed by a community-level physiological profile (CLPP) and 16S rRNA bacterial community profiles determined by denaturing gradient gel electrophoresis (DGGE). Saturated PHCs remaining in the soil were assessed by gas chromatography-mass spectrometry (GC-MS). Cumulative soil respiration increased 4- to 6-fold with the addition of carboxylates, while diesel contamination resulted in a small, but similar, increase across all carboxylate treatments. The addition of carboxylates resulted in distinct changes to the microbial community in both contaminated and uncontaminated soils but only a small increase in the biodegradation of saturated PHCs as measured by the n-C17 : pristane biomarker. We conclude that while the addition of citrate and malonate had little direct effect on the biodegradation of saturated hydrocarbons present in diesel, their effect on the microbial community leads us to suggest further studies using a variety of soils and organic acids, and linked to in situ studies of plants, to investigate the role of carboxylates in microbial community dynamics.

Intergenerational studies on the effects of cerium oxide nanoparticles in wheat

EPA Science Inventory

The intergenerational impacts of engineered nanomaterials in plants are not yet well understood. A soil microcosm study was performed to assess the physiology, phenology, yield and nutrient uptake in wheat (Triticum aestivum) exposed to nanoceria (nCeO2). Seeds from parental plan...

Variances and uncertainties of the sample laboratory-to-laboratory variance (S(L)2) and standard deviation (S(L)) associated with an interlaboratory study.

PubMed

McClure, Foster D; Lee, Jung K

2012-01-01

The validation process for an analytical method usually employs an interlaboratory study conducted as a balanced completely randomized model involving a specified number of randomly chosen laboratories, each analyzing a specified number of randomly allocated replicates. For such studies, formulas to obtain approximate unbiased estimates of the variance and uncertainty of the sample laboratory-to-laboratory (lab-to-lab) STD (S(L)) have been developed primarily to account for the uncertainty of S(L) when there is a need to develop an uncertainty budget that includes the uncertainty of S(L). For the sake of completeness on this topic, formulas to estimate the variance and uncertainty of the sample lab-to-lab variance (S(L)2) were also developed. In some cases, it was necessary to derive the formulas based on an approximate distribution for S(L)2.

Links between sulphur oxidation and sulphur-oxidising bacteria abundance and diversity in soil microcosms based on soxB functional gene analysis.

PubMed

Tourna, Maria; Maclean, Paul; Condron, Leo; O'Callaghan, Maureen; Wakelin, Steven A

2014-06-01

Sulphur-oxidising bacteria (SOB) play a key role in the biogeochemical cycling of sulphur in soil ecosystems. However, the ecology of SOB is poorly understood, and there is little knowledge about the taxa capable of sulphur oxidation, their distribution, habitat preferences and ecophysiology. Furthermore, as yet there are no conclusive links between SOB community size or structure and rates of sulphur oxidation. We have developed a molecular approach based on primer design targeting the soxB functional gene of nonfilamentous chemolithotrophic SOB that allows assessment of both abundance and diversity. Cloning and sequencing revealed considerable diversity of known soxB genotypes from agricultural soils and also evidence for previously undescribed taxa. In a microcosm experiment, abundance of soxB genes increased with sulphur oxidation rate in soils amended with elemental sulphur. Addition of elemental sulphur to soil had a significant effect in the soxB gene diversity, with the chemolithotrophic Thiobacillus-like Betaproteobacteria sequences dominating clone libraries 6 days after sulphur application. Using culture-independent methodology, the study provides evidence for links between abundance and diversity of SOB and sulphur oxidation. The methodology provides a new tool for investigation of the ecology and role of SOB in soil sulphur biogeochemistry. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

21 CFR 58.130 - Conduct of a nonclinical laboratory study.

Code of Federal Regulations, 2010 CFR

2010-04-01

... specimen in a manner that precludes error in the recording and storage of data. (d) Records of gross... that specimen histopathologically. (e) All data generated during the conduct of a nonclinical laboratory study, except those that are generated by automated data collection systems, shall be recorded...

21 CFR 58.130 - Conduct of a nonclinical laboratory study.

Code of Federal Regulations, 2013 CFR

2013-04-01

... specimen in a manner that precludes error in the recording and storage of data. (d) Records of gross... that specimen histopathologically. (e) All data generated during the conduct of a nonclinical laboratory study, except those that are generated by automated data collection systems, shall be recorded...

21 CFR 58.130 - Conduct of a nonclinical laboratory study.

Code of Federal Regulations, 2011 CFR

2011-04-01

... specimen in a manner that precludes error in the recording and storage of data. (d) Records of gross... that specimen histopathologically. (e) All data generated during the conduct of a nonclinical laboratory study, except those that are generated by automated data collection systems, shall be recorded...

SEWER SEDIMENT GATE AND VACUUM FLUSHING TANKS: LABORATORY FLUME STUDIES

EPA Science Inventory

The objective of this study was to test the performance of a traditional gate-flushing device and a newly designed vacuum-flushing device in removing sediments from combined sewers and CSO storage tanks. A laboratory hydraulic flune was used to simulate a reach of sewer or storag...

Biogeochemical modeling of CO 2 and CH 4 production in anoxic Arctic soil microcosms

DOE PAGES

Tang, Guoping; Zheng, Jianqiu; Xu, Xiaofeng; ...

2016-09-12

Soil organic carbon turnover to CO 2 and CH 4 is sensitive to soil redox potential and pH conditions. But, land surface models do not consider redox and pH in the aqueous phase explicitly, thereby limiting their use for making predictions in anoxic environments. Using recent data from incubations of Arctic soils, we extend the Community Land Model with coupled carbon and nitrogen (CLM-CN) decomposition cascade to include simple organic substrate turnover, fermentation, Fe(III) reduction, and methanogenesis reactions, and assess the efficacy of various temperature and pH response functions. Incorporating the Windermere Humic Aqueous Model (WHAM) enables us to approximatelymore » describe the observed pH evolution without additional parameterization. Though Fe(III) reduction is normally assumed to compete with methanogenesis, the model predicts that Fe(III) reduction raises the pH from acidic to neutral, thereby reducing environmental stress to methanogens and accelerating methane production when substrates are not limiting. Furthermore, the equilibrium speciation predicts a substantial increase in CO 2 solubility as pH increases, and taking into account CO 2 adsorption to surface sites of metal oxides further decreases the predicted headspace gas-phase fraction at low pH. Without adequate representation of these speciation reactions, as well as the impacts of pH, temperature, and pressure, the CO 2 production from closed microcosms can be substantially underestimated based on headspace CO 2 measurements only. Our results demonstrate the efficacy of geochemical models for simulating soil biogeochemistry and provide predictive understanding and mechanistic representations that can be incorporated into land surface models to improve climate predictions.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whitford, W.G.; Elkins, N.Z.; Parker, L.W.

In laboratory microcosms of coal mine spoil amended with bark and wood chips, the activity of termites increased organic matter and increased total nitrogen. Termite survival was reduced in microcosms with spoil and paper or straw amendments. Field studies evaluating the efficacy of organic amendments in developing a soil biota showed that decomposition rates of wood chip-bark amended spoil were the same as unmined soil and that decomposition rates were lower than all other mulch-spoil combinations. Wood and bark amended-spoil had the highest density and diversity of soil fauna. Top dressing spoils with borrow soil did not improve any ofmore » the soil biological parameters measured. Based on these data it was recommended that reclamation procedures be changed to eliminate borrow soil top-dressing and that wood removed from mined areas be returned to the contoured spoil as wood chip amendment in addition to straw mulch.« less

The ability of indigenous micro-organisms to degrade isoproturon, atrazine and mecoprop within aerobic UK aquifer systems.

PubMed

Johnson, Andrew C; White, Craig; Bhardwaj, C Lal; Dixon, Andy

2003-12-01

The potential for the herbicides isoproturon, atrazine and mecoprop to degrade in the major UK aquifers of chalk, sandstone and limestone was studied using laboratory microcosms spiked at 100 microg litre(-1). Significant mecoprop degradation was only observed in sandstone groundwater samples. Atrazine transformation, based on the formation of metabolites, did occur in most groundwater samples, but only at a rate of 1-3% per year. A potential to degrade isoproturon was observed in groundwater samples from each of the aquifer types, with the most rapid and consistent degradation occurring at the sandstone field site. Biodegradation was confirmed by the formation of monodesmethyl- and didesmethyl-isoproturon. Isoproturon degradation potential rates obtained from the groundwater microcosms could not be correlated with either dissolved organic carbon or numbers of bacteria in the groundwater. It was noted that the ability of the groundwater at a field site to degrade a pesticide was not related to performance of the soil above.

Safety in laboratories: Indian scenario.

PubMed

Mustafa, Ajaz; Farooq, A Jan; Qadri, Gj; S A, Tabish

2008-07-01

Health and safety in clinical laboratories is becoming an increasingly important subject as a result of emergence of highly infectious diseases such as Hepatitis and HIV. A cross sectional study was carried out to study the safety measures being adopted in clinical laboratories of India. Heads of laboratories of teaching hospitals of India were subjected to a standardized, pretested questionnaire. Response rate was 44.8%. only 60% of laboratories had person in-charge of safety in laboratory. Seventy three percent of laboratories had safety education program regarding hazards. In 91% of laboratories staff is using protective clothing while working in laboratories. Hazardous material regulations are followed in 78% of laboratories. Regular health check ups are carried among laboratory staff in 43.4% of laboratories.Safety manual is available in 56.5% of laboratories. 73.9% of laboratories are equipped with fire extinguishers. Fume cupboards are provided in 34.7% of laboratories and they are regularly checked in 87.5% of these laboratories. In 78.26% of laboratories suitable measures are taken to minimize formation of aerosols.In 95.6% of laboratories waste is disposed off as per bio-medical waste management handling rules. Laboratory of one private medical college was accredited with NABL and safety parameters were better in that laboratory. Installing safety engineered devices apparently contributes to significant decrease in injuries in laboratories; laboratory safety has to be a part of overall quality assurance programme in hospitals. Accreditation has to be made necessary for all laboratories.

Linking Stoichiometric Homeostasis of Microorganisms with Soil Phosphorus Dynamics in Wetlands Subjected to Microcosm Warming

PubMed Central

Wang, Hang; Li, HongYi; Zhang, ZhiJian; Muehlbauer, Jeffrey D.; He, Qiang; Xu, XinHua; Yue, ChunLei; Jiang, DaQian

2014-01-01

Soil biogeochemical processes and the ecological stability of wetland ecosystems under global warming scenarios have gained increasing attention worldwide. Changes in the capacity of microorganisms to maintain stoichiometric homeostasis, or relatively stable internal concentrations of elements, may serve as an indicator of alterations to soil biogeochemical processes and their associated ecological feedbacks. In this study, an outdoor computerized microcosm was set up to simulate a warmed (+5°C) climate scenario, using novel, minute-scale temperature manipulation technology. The principle of stoichiometric homeostasis was adopted to illustrate phosphorus (P) biogeochemical cycling coupled with carbon (C) dynamics within the soil-microorganism complex. We hypothesized that enhancing the flux of P from soil to water under warming scenarios is tightly coupled with a decrease in homeostatic regulation ability in wetland ecosystems. Results indicate that experimental warming impaired the ability of stoichiometric homeostasis (H) to regulate biogeochemical processes, enhancing the ecological role of wetland soil as an ecological source for both P and C. The potential P flux from soil to water ranged from 0.11 to 34.51 mg m−2 d−1 in the control and 0.07 to 61.26 mg m−2 d−1 in the warmed treatment. The synergistic function of C-P acquisition is an important mechanism underlying C∶P stoichiometric balance for soil microorganisms under warming. For both treatment groups, strongly significant (p<0.001) relationships fitting a negative allometric power model with a fractional exponent were found between n-HC∶P (the specialized homeostatic regulation ability as a ratio of soil highly labile organic carbon to dissolved reactive phosphorus in porewater) and potential P flux. Although many factors may affect soil P dynamics, the n-HC∶P term fundamentally reflects the stoichiometric balance or interactions between the energy landscape (i.e., C) and flow of resources

A cross-laboratory preclinical study on the effectiveness of interleukin-1 receptor antagonist in stroke

PubMed Central

Maysami, Samaneh; Wong, Raymond; Pradillo, Jesus M; Denes, Adam; Dhungana, Hiramani; Malm, Tarja; Koistinaho, Jari; Orset, Cyrille; Rahman, Mahbubur; Rubio, Marina; Schwaninger, Markus; Vivien, Denis; Bath, Philip M; Rothwell, Nancy J

2015-01-01

Stroke represents a global challenge and is a leading cause of permanent disability worldwide. Despite much effort, translation of research findings to clinical benefit has not yet been successful. Failure of neuroprotection trials is considered, in part, due to the low quality of preclinical studies, low level of reproducibility across different laboratories and that stroke co-morbidities have not been fully considered in experimental models. More rigorous testing of new drug candidates in different experimental models of stroke and initiation of preclinical cross-laboratory studies have been suggested as ways to improve translation. However, to our knowledge, no drugs currently in clinical stroke trials have been investigated in preclinical cross-laboratory studies. The cytokine interleukin 1 is a key mediator of neuronal injury, and the naturally occurring interleukin 1 receptor antagonist has been reported as beneficial in experimental studies of stroke. In the present paper, we report on a preclinical cross-laboratory stroke trial designed to investigate the efficacy of interleukin 1 receptor antagonist in different research laboratories across Europe. Our results strongly support the therapeutic potential of interleukin 1 receptor antagonist in experimental stroke and provide further evidence that interleukin 1 receptor antagonist should be evaluated in more extensive clinical stroke trials. PMID:26661169

Laboratory performance in the Sediment Laboratory Quality-Assurance Project, 1996-98

USGS Publications Warehouse

Gordon, John D.; Newland, Carla A.; Gagliardi, Shane T.

2000-01-01

Analytical results from all sediment quality-control samples are compiled and statistically summarized by the USGS, Branch of Quality Systems, both on an intra- and interlaboratory basis. When evaluating these data, the reader needs to keep in mind that every measurement has an error component associated with it. It is premature to use the data from the first five SLQA studies to judge any of the laboratories as performing in an unacceptable manner. There were, however, some notable differences in the results for the 12 laboratories that participated in the five SLQA studies. For example, the overall median percent difference for suspended-sediment concentration on an individual laboratory basis ranged from –18.04 to –0.33 percent. Five of the 12 laboratories had an overall median percent difference for suspended-sediment concentration of –2.02 to –0.33 percent. There was less variability in the median difference for the measured fine-size material mass. The overall median percent difference for fine-size material mass ranged from –10.11 to –4.27 percent. Except for one laboratory, the median difference for fine-size material mass was within a fairly narrow range of –6.76 to –4.27 percent. The median percent difference for sand-size material mass differed among laboratories more than any other physical sediment property measured in the study. The overall median percent difference for the sand-size material mass ranged from –1.49 percent to 26.39 percent. Five of the nine laboratories that do sand/fine separations had overall median percent differences that ranged from –1.49 to 2.98 percent for sand-size material mass. Careful review of the data reveals that certain laboratories consistently produced data within statistical control limits for some or all of the physical sediment properties measured in this study, whereas other laboratories occasionally produced data that exceeded the control limits.

Assessment of factors limiting algal growth in acidic pit lakes--a case study from Western Australia, Australia.

PubMed

Kumar, R Naresh; McCullough, Clint D; Lund, Mark A; Larranaga, Santiago A

2016-03-01

Open-cut mining operations can form pit lakes on mine closure. These new water bodies typically have low nutrient concentrations and may have acidic and metal-contaminated waters from acid mine drainage (AMD) causing low algal biomass and algal biodiversity. A preliminary study was carried out on an acidic coal pit lake, Lake Kepwari, in Western Australia to determine which factors limited algal biomass. Water quality was monitored to obtain baseline data. pH ranged between 3.7 and 4.1, and solute concentrations were slightly elevated to levels of brackish water. Concentrations of N were highly relative to natural lakes, although concentrations of FRP (<0.01 mg/L) and C (total C 0.7-3.7 and DOC 0.7-3.5 mg/L) were very low, and as a result, algal growth was also extremely low. Microcosm experiment was conducted to test the hypothesis that nutrient enrichment will be able to stimulate algal growth regardless of water quality. Microcosms of Lake Kepwari water were amended with N, P and C nutrients with and without sediment. Nutrient amendments under microcosm conditions could not show any significant phytoplankton growth but was able to promote benthic algal growth. P amendments without sediment showed a statistically higher mean algal biomass concentration than controls or microcosms amended with phosphorus but with sediment did. Results indicated that algal biomass in acidic pit lake (Lake Kepwari) may be limited primarily by low nutrient concentrations (especially phosphorus) and not by low pH or elevated metal concentrations. Furthermore, sediment processes may also reduce the nutrient availability.

Fate, toxicity and bioconcentration of cadmium on Pseudokirchneriella subcapitata and Lemna minor in mid-term single tests.

PubMed

Clément, Bernard; Lamonica, Dominique

2018-03-01

In the frame of a project which consists in modeling a laboratory microcosm under cadmium pressure, we initiated this study on the fate and effects of cadmium in the presence of either the microalga Pseudokirchneriella subcapitata or the duckweed Lemna minor, two organisms of the microcosm. For each organism, growth inhibition tests on a duration of 2-3 weeks were carried out with the objective of linking effects with total dissolved, ionic and internalized forms of cadmium. Numbers of organisms (algal cells or duckweed fronds) in 2-L beakers filled with synthetic nutritive medium containing EDTA were counted during the course of assays, while cadmium concentrations in the water and in the organisms were measured. Free cadmium fraction was calculated using PHREEQC, a computer program for chemical speciation. Results showed that cadmium toxicity to microalgae could be correlated to the free divalent fraction of this metal, limited by the presence of EDTA, and to its concentration in the organisms. Bioconcentration factors for our medium were suggested for P. subcapitata (111,000 on the basis of free cadmium concentration) and L. minor (17,812 on the basis of total dissolved concentration). No effect concentrations were roughly estimated around 400 µg/g for Pseudokirchneriella subcapitata and 200-300 µg/g for Lemna minor. This study is a first step towards a fate model based on chemical speciation for a better understanding of microcosm results.

Biofilm resilience to desiccation in groundwater aquifers: a laboratory and field study.

PubMed

Weaver, L; Webber, J B; Hickson, A C; Abraham, P M; Close, M E

2015-05-01

Groundwater is used as a precious resource for drinking water worldwide. Increasing anthropogenic activity is putting increasing pressure on groundwater resources. One impact of increased groundwater abstraction coupled with increasing dry weather events is the lowering of groundwater levels within aquifers. Biofilms within groundwater aquifers offer protection to the groundwater by removing contaminants entering the aquifer systems from land use activities. The study presented investigated the impact of desiccation events on the biofilms present in groundwater aquifers using field and laboratory experiments. In both field and laboratory experiments a reduction in enzyme activity (glucosidase, esterase and phosphatase) was seen during desiccation compared to wet controls. However, comparing all the data together no significant differences were seen between either wet or desiccated samples or between the start and end of the experiments. In both field and laboratory experiments enzyme activity recovered to start levels after return to wet conditions. The study shows that biofilms within groundwater systems are resilient and can withstand periods of desiccation (4 months). Copyright © 2014 Elsevier B.V. All rights reserved.

A STUDY OF SMALL GROUP DYNAMICS AND PRODUCTIVITY IN THE BSCS LABORATORY BLOCK PROGRAM.

ERIC Educational Resources Information Center

HURD, PAUL DEHART; ROWE, MARY BUDD

THE RELATIONSHIP BETWEEN SMALL GROUP COMPATIBILITY AND ACHIEVEMENT IN THE BIOLOGICAL SCIENCE CURRICULUM STUDY LABORATORY BLOCK PROGRAM WAS TESTED. STUDENTS IN 14 CLASSES FROM FOUR HIGH SCHOOLS WERE ASSIGNED TO FOUR-MEMBER LABORATORY GROUPS CLASSIFIED AS COMPATIBLE OR INCOMPATIBLE. GROUP CLASSIFICATION WAS VALIDATED BY OBSERVERS WHO WERE NOT AWARE…

[Laboratory and clinical study of intravenous miconazole].

PubMed

Sawae, Y; Okada, K; Kumagai, Y

1987-02-01

Laboratory and clinical study was carried out on miconazole (MCZ), a new synthetic imidazole. The antifungal activity of MCZ was studied and expressed as MICs for clinical isolates. The drug proved to have the highest activity against Cryptococcus neoformans, with MICs of no more than 0.16 micrograms/ml for all isolates of this species. MICs of Torulopsis glabrata were 0.08-5 micrograms/ml for all isolates and those of Candida albicans and Candida tropicalis were 5-20 micrograms/ml for more than 90% of the isolates. Most of other strains were less than 10 micrograms/ml. When 3 healthy adult men were administered each with 200 mg of MCZ by intravenous drip infusion for 1.25 hours, the mean serum MCZ concentration was 1.39 micrograms/ml at the end of the infusion, then decreased rapidly to 0.49 microgram/ml in following 30 minutes, and then decreased gradually to 0.17 microgram/ml 6 hours later. The mean cumulative urinary excretion rate of the drug was as low as 3.0% at this stage. A total of 25 patients with ages of 30-78 years, comprising 17 men and 8 women, were treated with 200-1,800 mg of MCZ daily for 3-93 days. The clinical effectiveness was ascertained in 19 cases among the patients; 9 cases with candidiasis, 3 with cryptococcosis and 7 with aspergillosis. Clinical responses were excellent in 2, good in 9 and poor in 8 cases, and its efficacy rates was 58%. The efficacy rate of the combination therapy with other antifungal agents was 60% in comparison with 57% of MCZ alone. Adverse reactions to the drug such as nausea, vomiting and anorexia were observed in 3 cases (12%). Abnormal changes in laboratory parameters were also observed: 3 patients with elevations of GOT and GPT, and another with eosinophilia.

[The external evaluation of study quality: the role in maintaining the reliability of laboratory information].

PubMed

Men'shikov, V V

2013-08-01

The external evaluation of quality of clinical laboratory examinations was gradually introduced in USSR medical laboratories since 1970s. In Russia, in the middle of 1990 a unified all-national system of external evaluation quality was organized known as the Federal center of external evaluation of quality at the basis of laboratory of the state research center of preventive medicine. The main positions of policy in this area were neatly formulated in the guidance documents of ministry of Health. Nowadays, the center of external evaluation of quality proposes 100 and more types of control studies and permanently extends their specter starting from interests of different disciplines of clinical medicine. The consistent participation of laboratories in the cycles of external evaluation of quality intrinsically promotes improvement of indicators of properness and precision of analysis results and increases reliability of laboratory information. However, a significant percentage of laboratories does not participate at all in external evaluation of quality or takes part in control process irregularly and in limited number of tests. The managers of a number of medical organizations disregard the application of the proposed possibilities to increase reliability of laboratory information and limit financing of studies in the field of quality control. The article proposes to adopt the national standard on the basis of ISO 17043 "Evaluation of compliance. The common requirements of professional competence testing".

Needs and Nonviolent Communication in the Religious Studies Classroom

ERIC Educational Resources Information Center

Agnew, Elizabeth N.

2012-01-01

Religious studies classrooms are microcosms of the public square in bringing together individuals of diverse identities and ideological commitments. As such, these classrooms create the necessity and opportunity to foster effective modes of conversation. In this essay, I argue that communication attuned to shared human needs--among them needs for…

A comparison of the survival of F+RNA and F+DNA coliphages in lake water microcosms.

PubMed

Long, Sharon C; Sobsey, Mark D

2004-03-01

The survival of seven F+RNA phages (MS2 Group I ATCC type strain, two Group I environmental isolates, a Group II environmental isolate, a Group III environmental isolate, and two Group IV environmental isolates) and six F+DNA phages (M13, fd, f1, and ZJ/2 ATCC type strains, and two environmental isolates) were examined in microcosms using a surface drinking water source. Phages were spiked into replicate aliquots of a source water at about 20,000 pfu/ml. Replicate spikes were incubated at 4 and 20 degrees C and monitored for 110 days. At 4 degrees C, Groups I and II F+ RNA phages were detectable through 110 days, with reductions of about 1 and 3 log10, respectively. The Group III F+RNA phage demonstrated 5 log10 reduction after 3 weeks, and the Group IV F+RNA phages were reduced to detection limits (5 log10 reduction) within 10 days. Of the F+DNA phages, all four type strains were detectable with about 2.5 log10 reduction after 110 days at 4 degrees C. The F+DNA environmental isolates were detectable with about a 4 log10 reduction after 110 days at 4 degrees C. All phages demonstrated faster decay at 20 degrees C. These results suggest that differences in F+ phage survival may influence their prevalence in environmental waters and the ability to attribute their prevalence to specific human and animal sources of faecal contamination.

Seven Principles of Instructional Content Design for a Remote Laboratory: A Case Study on ERRL

ERIC Educational Resources Information Center

Cagiltay, N. E.; Aydin, E.; Aydin, C. C.; Kara, A.; Alexandru, M.

2011-01-01

This paper discusses the results of a study of the requirements for developing a remote radio frequency (RF) laboratory for electrical engineering students. It investigates students' preferred usage of the technical content of a state-of-the-art RF laboratory. The results of this study are compared to previous findings, which dealt with other user…

Case study: improving efficiency in a large hospital laboratory.

PubMed

Bartel, Marilynn

2004-01-01

Saint Francis Health System (SFHS) consists of three hospitals and one clinic: Saint Francis Hospital (SFH); Broken Arrow Medical Center; Laureate Psychiatric Hospital; and Warren Clinic. SFHS has 670 physicians on staff and serves medical (oncology, orthopedic, neurology, and renal), surgical, cardiac, women and infant, pediatric, transplant, and trauma patients in Tulsa County, Oklahoma, which has a population of 660,000. SFH incorporates 706 staffed beds, including 126 pediatric beds and 119 critical care beds. Each year, the health system averages 38,000 admissions, 70,000 emergency department visits, 25,000 surgeries, and 3,500 births. Saint Francis Laboratory is located within the main hospital facility (SFH) and functions as a core lab for the health system. The lab also coordinates lab services with Saint Francis Heart Hospital, a physician-system joint venture. The Optimal Equipment Configuration (OEC) Project was designed by the Clinical Laboratory Services division of Premier, a group purchasing organization, with the goal of determining whether laboratories could improve efficiency and decrease unit cost by using a single-source vendor. Participants included seven business partners (Abbott, Bayer, Beckman/Coulter, Dade/Behring, J&J/ Ortho, Olympus, and Roche) and 21 laboratory sites (a small, mid-sized, and large site for each vendor). SFH laboratory staff embraced Premier's concept and viewed the OEC project as an opportunity to "energize" laboratory operations. SFH partnered with Abbott, their primary equipment vendor, for the project. Using resources and tools made available through the project, the laboratory was re-engineered to simplify workflow, increase productivity, and decrease costs by adding automation and changing to centralized specimen processing. Abbott and SFH shared a common vision for the project and enhanced their partnership through increased communication and problem solving. Abbott's area representatives provided for third