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1.
J Environ Manage ; 280: 111710, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33308931

RESUMO

Reducing harmful algal blooms in Lake Erie, situated between the United States and Canada, requires implementing best management practices to decrease nutrient loading from upstream sources. Bi-national water quality targets have been set for total and dissolved phosphorus loads, with the ultimate goal of reaching these targets in 9-out-of-10 years. Row crop agriculture dominates the land use in the Western Lake Erie Basin thus requiring efforts to mitigate nutrient loads from agricultural systems. To determine the types and extent of agricultural management practices needed to reach the water quality goals, we used five independently developed Soil and Water Assessment Tool models to evaluate the effects of 18 management scenarios over a 10-year period on nutrient export. Guidance from a stakeholder group was provided throughout the project, and resulted in improved data, development of realistic scenarios, and expanded outreach. Subsurface placement of phosphorus fertilizers, cover crops, riparian buffers, and wetlands were among the most effective management options. But, only in one realistic scenario did a majority (3/5) of the models predict that the total phosphorus loading target would be met in 9-out-of-10 years. Further, the dissolved phosphorus loading target was predicted to meet the 9-out-of-10-year goal by only one model and only in three scenarios. In all scenarios evaluated, the 9-out-of-10-year goal was not met based on the average of model predictions. Ensemble modeling revealed general agreement about the effects of several practices although some scenarios resulted in a wide range of uncertainty. Overall, our results demonstrate that there are multiple pathways to approach the established water quality goals, but greater adoption rates of practices than those tested here will likely be needed to attain the management targets.


Assuntos
Monitoramento Ambiental , Lagos , Agricultura , Canadá , Eutrofização , Fósforo/análise , Qualidade da Água
2.
Sci Total Environ ; 759: 143920, 2021 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-33339624

RESUMO

The need for effective water quality models to help guide management and policy, and extend monitoring information, is at the forefront of recent discussions related to watershed management. These models are often calibrated and validated at the basin outlet, which ensures that models are capable of evaluating basin scale hydrology and water quality. However, there is a need to understand where these models succeed or fail with respect to internal process representation, as these watershed-scale models are used to inform management practices and mitigation strategies upstream. We evaluated an ensemble of models-each calibrated to in-stream observations at the basin outlet-against discharge and nutrient observations at the farm field scale to determine the extent to which these models capture field-scale dynamics. While all models performed well at the watershed outlet, upstream performance varied. Models tended to over-predict discharge through surface runoff and subsurface drainage, while under-predicting phosphorus loading through subsurface drainage and nitrogen loading through surface runoff. Our study suggests that while models may be applied to predict impacts of management at the basin scale, care should be taken in applying the models to evaluate field-scale management and processes in the absence of data that can be incorporated at that scale, even with the use of multiple models.

3.
J Environ Manage ; 279: 111803, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33341725

RESUMO

Coastal eutrophication is a leading cause of degraded water quality around the world. Identifying the sources and their relative contributions to impaired downstream water quality is an important step in developing management plans to address water quality concerns. Recent mass-balance studies of Total Phosphorus (TP) loads of the Maumee River watershed highlight the considerable phosphorus contributions of non-point sources, including agricultural sources, degrading regional downstream water quality. This analysis builds upon these mass-balance studies by using the Soil and Water Assessment Tool to simulate the movement of phosphorus from manure, inorganic fertilizer, point sources, and soil sources, and respective loads of TP and Dissolved Reactive Phosphorus (DRP). This yields a more explicit estimation of source contribution from the watershed. Model simulations indicate that inorganic fertilizers contribute a greater proportion of TP (45% compared to 8%) and DRP (58% compared to 12%) discharged from the watershed than manure sources in the March-July period, the season driving harmful algal blooms. Although inorganic fertilizers contributed a greater mass of TP and DRP than manure sources, the two sources had similar average delivery fractions of TP (2.7% for inorganic fertilizers vs. 3.0% for manure sources) as well as DRP (0.7% for inorganic fertilizers vs. 1.2% for manure sources). Point sources contributed similar proportions of TP (5%) and DRP (12%) discharged in March-July as manure sources. Soil sources of phosphorus contributed over 40% of the March-July TP load and 20% of the March-July DRP load from the watershed to Lake Erie. Reductions of manures and inorganic fertilizers corresponded to a greater proportion of phosphorus delivered from soil sources of phosphorus, indicating that legacy phosphorus in soils may need to be a focus of management efforts to reach nutrient load reduction goals. In agricultural watersheds aground the world, including the Maumee River watershed, upstream nutrient management should not focus solely on an individual nutrient source; rather a comprehensive approach involving numerous sources should be undertaken.


Assuntos
Lagos , Fósforo , Agricultura , Monitoramento Ambiental , Fósforo/análise , Rios , Qualidade da Água
4.
J Environ Manage ; : 111506, 2020 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-33168300

RESUMO

Watershed-scale hydrologic models are frequently used to inform conservation and restoration efforts by identifying critical source areas (CSAs; alternatively 'hotspots'), defined as areas that export relatively greater quantities of nutrients and sediment. The CSAs can then be prioritized or 'targeted' for conservation and restoration to ensure efficient use of limited resources. However, CSA simulations from watershed-scale hydrologic models may be uncertain and it is critical that the extent and implications of this uncertainty be conveyed to stakeholders and decision makers. We used an ensemble of four independently developed Soil and Water Assessment Tool (SWAT) models and a SPAtially Referenced Regression On Watershed attributes (SPARROW) model to simulate CSA locations for flow, phosphorus, nitrogen, and sediment within the ~17,000-km2 Maumee River watershed at the HUC-12 scale. We then assessed uncertainty in CSA simulations determined as the variation in CSA locations across the models. Our application of an ensemble of models - differing with respect to inputs, structure, and parameterization - facilitated an improved accounting of CSA prediction uncertainty. We found that the models agreed on the location of a subset of CSAs, and that these locations may be targeted with relative confidence. However, models more often disagreed on CSA locations. On average, only 16%-46% of HUC-12 subwatersheds simulated as a CSA by one model were also simulated as a CSA by a different model. Our work shows that simulated CSA locations are highly uncertain and may vary substantially across models. Hence, while models may be useful in informing conservation and restoration planning, their application to identify CSA locations would benefit from comprehensive uncertainty analyses to avoid inefficient use of limited resources.

5.
J Environ Manage ; 276: 111248, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32891029

RESUMO

The discharge of excess nutrients to surface waters causes eutrophication, resulting in algal blooms, hypoxia, degraded water quality, reduced and contaminated fisheries, threats to potable water supplies, and decreases in tourism, cultural activities, and coastal economies. An understanding of the contribution of urban runoff to eutrophication is needed to inform management strategies. More broadly, the seasonality in nutrient concentrations and loads in urban runoff needs further analysis since algal blooms and hypoxia are seasonal in nature. This study quantifies the variation of nutrients and sediment in stormwater runoff across seasons from four urban residential sewersheds located in Columbus, Ohio, USA. An average of 62 runoff events at each sewershed were sampled using automated samplers during stormflow and analyzed for nutrients and total suspended solids (TSS). Spring total nitrogen concentrations had a significantly (p < 0.05) higher median concentration (2.19 mg/L) than fall (1.55 mg/L) and summer (1.50 mg/L). Total phosphorus concentrations were significantly higher in spring (0.22 mg/L) and fall (0.23 mg/L) than summer (0.15 mg/L). TSS concentrations were significantly higher in the spring (74.5 mg/L) and summer (56.5 mg/L) than the fall (34.0 mg/L). In contrast, seasonal loading differences for nutrients or sediment were rare because runoff volume varied in such a way as to offset significant concentration differences and significant seasonality in rainfall intensity. Annual pollutant loadings were similar in magnitude to other residential and even some agricultural runoff studies. Although nutrient loads are the key indicator for determining algal biomass, nutrient concentrations are important for real-time algal growth. Future research efforts should be focused not only on understanding how seasonal urban concentrations and loads impact coastal eutrophication, but also developing improved watershed management focused on critical periods. Improved designs for stormwater control measures need to account for seasonality in pollutant discharge.


Assuntos
Chuva , Poluentes Químicos da Água , Monitoramento Ambiental , Nitrogênio/análise , Nutrientes , Ohio , Fósforo/análise , Movimentos da Água , Poluentes Químicos da Água/análise
6.
Sci Total Environ ; 747: 141112, 2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-32791405

RESUMO

How anticipated climate change might affect long-term outcomes of present-day agricultural conservation practices remains a key uncertainty that could benefit water quality and biodiversity conservation planning. To explore this issue, we forecasted how the stream fish communities in the Western Lake Erie Basin (WLEB) would respond to increasing amounts of agricultural conservation practice (ACP) implementation under two IPCC future greenhouse gas emission scenarios (RCP4.5: moderate reductions; RCP8.5: business-as-usual conditions) during 2020-2065. We used output from 19 General Circulation Models to drive linked agricultural land use (APEX), watershed hydrology (SWAT), and stream fish distribution (boosted regression tree) models, subsequently analyzing how projected changes in habitat would influence fish community composition and functional trait diversity. Our models predicted both positive and negative effects of climate change and ACP implementation on WLEB stream fishes. For most species, climate and ACPs influenced species in the same direction, with climate effects outweighing those of ACP implementation. Functional trait analysis helped clarify the varied responses among species, indicating that more extreme climate change would reduce available habitat for large-bodied, cool-water species with equilibrium life-histories, many of which also are of importance to recreational fishing (e.g., northern pike, smallmouth bass). By contrast, available habitat for warm-water, benthic species with more periodic or opportunistic life-histories (e.g., northern hogsucker, greater redhorse, greenside darter) was predicted to increase. Further, ACP implementation was projected to hasten these shifts, suggesting that efforts to improve water quality could come with costs to other ecosystem services (e.g., recreational fishing opportunities). Collectively, our findings demonstrate the need to consider biological outcomes when developing strategies to mitigate water quality impairment and highlight the value of physical-biological modeling approaches to agricultural and biological conservation planning in a changing climate.


Assuntos
Ecossistema , Rios , Agricultura , Animais , Mudança Climática , Conservação dos Recursos Naturais , Hidrologia
7.
Sci Total Environ ; 724: 138004, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32408425

RESUMO

Hydrologic models are applied increasingly with climate projections to provide insights into future hydrologic conditions. However, both hydrologic models and climate models can produce a wide range of predictions based on model inputs, assumptions, and structure. To characterize a range of future predictions, it is common to use multiple climate models to drive hydrologic models, yet it is less common to also use a suite of hydrologic models. It is also common for hydrologic models to report riverine discharge and assume that nutrient loading will follow similar patterns, but this may not be the case. In this study, we characterized uncertainty from both climate models and hydrologic models in predicting riverine discharge and nutrient loading. Six climate models drawn from the Coupled Model Intercomparison Project Phase 5 ensemble were used to drive five independently developed and calibrated Soil and Water Assessment Tool models to assess hydrology and nutrient loadings for mid-century (2046-2065) in the Maumee River Watershed,the largest watershedsdraining to the Laurentian Great Lakes. Under those conditions, there was no clear agreement on the direction of change in future nutrient loadings or discharge. Analysis of variance demonstrated that variation among climate models was the dominant source of uncertainty in predicting future total discharge, tile discharge (i.e. subsurface drainage), evapotranspiration, and total nitrogen loading, while hydrologic models were the main source of uncertainty in predicted surface runoff and phosphorus loadings. This innovative study quantifies the importance of hydrologic model in the prediction of riverine nutrient loadings under a future climate.

8.
Sci Total Environ ; 723: 138033, 2020 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-32392682

RESUMO

Non-point stormwater runoff is a major contamination source of receiving waterbodies. Heightened incidence of waterborne disease outbreaks related to recreational use and source water contamination is associated with extreme rainfall events. Such extreme events are predicted to increase in some regions due to climate change. Consequently, municipal separate storm sewer systems (MS4s) conveying pathogens to receiving waters are a growing public health concern. In addition, the spread of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria in various environmental matrices, including urban runoff, is an emerging threat. The resistome and microbiota profile of MS4 discharges has yet to be fully characterized. To address this knowledge gap, we first analyzed the relationship between rainfall depth and intensity and E. coli densities (fecal indicator) in stormwater from four MS4 outflows in Columbus, Ohio, USA during the spring and summer of 2017. Microbial source tracking (MST) was conducted to examine major fecal contamination sources in the study sewersheds. A subset of samples was analyzed for microbial and resistome profiles using a metagenomic approach. The results showed a significant positive relationship between outflow E. coli density and rainfall intensity. MST results indicate prevalent fecal contamination from ruminant populations in the study sites (91% positive among the samples tested). Protobacteria and Actinobacteria were two dominant bacteria at a phylum level. A diverse array of ARGs and potentially pathogenic bacteria (e.g. Salmonella enterica Typhimurium), fungi (e.g. Scedosporium apiospermum), and protists (e.g. Acanthamoeba palestinensis) were found in urban stormwater outflows that discharge into adjacent streams. The most prevalent ARGs among samples were ß-lactam resistance genes and the most predominant virulence genes within bacterial community were related with Staphylococcus aureus. A comprehensive contamination profile indicates a need for sustainable strategies to manage urban stormwater runoff amid increasingly intense rainfall events to protect public and environmental health.


Assuntos
Microbiota , Microbiologia da Água , Resistência Microbiana a Medicamentos , Monitoramento Ambiental , Escherichia coli , Ohio , Chuva
10.
Behav Res Methods ; 51(4): 1706-1716, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30761464

RESUMO

With the explosion of "big data," digital repositories of texts and images are growing rapidly. These datasets present new opportunities for psychological research, but they require new methodologies before researchers can use these datasets to yield insights into human cognition. We present a new method that allows psychological researchers to take advantage of text and image databases: a procedure for measuring human categorical representations over large datasets of items, such as arbitrary words or pictures. We call this method discrete Markov chain Monte Carlo with people (d-MCMCP). We illustrate our method by evaluating the following categories over datasets: emotions as represented by facial images, moral concepts as represented by relevant words, and seasons as represented by images drawn from large online databases. Three experiments demonstrate that d-MCMCP is powerful and flexible enough to work with complex, naturalistic stimuli drawn from large online databases.


Assuntos
Cadeias de Markov , Método de Monte Carlo , Cognição , Bases de Dados Factuais , Emoções , Humanos
11.
Harmful Algae ; 77: 1-10, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30005796

RESUMO

Mycosporine-like amino acids (MAAs) are UV-absorbing metabolites found in cyanobacteria. While their protective role from UV in Microcystis has been studied in a laboratory setting, a full understanding of the ecology of MAA-producing versus non-MAA-producing Microcystis in natural environments is lacking. This study presents a new tool for quantifying MAA-producing Microcystis and applies it to obtain insight into the dynamics of MAA-producing and non-MAA-producing Microcystis in Lake Erie. This study first developed a sensitive, specific TaqMan real-time PCR assay that targets MAA synthetase gene C (mysC) of Microcystis (quantitative range: 1.7 × 101 to 1.7 × 107 copies/assay). Using this assay, Microcystis was quantified with a MAA-producing genotype (mysC+) in water samples (n = 96) collected during March-November 2013 from 21 Lake Erie sites (undetectable - 8.4 × 106 copies/ml). The mysC+ genotype comprised 0.3-37.8% of the Microcystis population in Lake Erie during the study period. The proportion of the mysC+ genotype during high solar UV irradiation periods (mean = 18.8%) was significantly higher than that during lower UV periods (mean = 9.7%). Among the MAAs, shinorine (major) and porphyra (minor) were detected with HPLC-PDA-MS/MS from the Microcystis isolates and water samples. However, no significant difference in the MAA concentrations existed between higher and lower solar UV periods when the MAA concentrations were normalized with Microcystis mysC abundance. Collectively, this study's findings suggest that the MAA-producing Microcystis are present in Lake Erie, and they may be ecologically advantageous under high UV conditions, but not to the point that they exclusively predominate over the non-MAA-producers.


Assuntos
Toxinas Bacterianas/metabolismo , Proliferação Nociva de Algas , Lagos/microbiologia , Microcystis/metabolismo , Reação em Cadeia da Polimerase em Tempo Real/métodos , Toxinas Bacterianas/análise , Microcystis/genética , Microcystis/crescimento & desenvolvimento , Ohio , Análise Espaço-Temporal
12.
Food Res Int ; 102: 234-245, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-29195944

RESUMO

Microcystin (MC), a hepatotoxin that can adversely affect human health, has become more prevalent in freshwater ecosystems worldwide, owing to an increase in toxic cyanobacteria blooms. While consumption of water and fish are well-documented exposure pathways of MCs to humans, less is known about the potential transfer to humans through consumption of vegetables that have been irrigated with MC-contaminated water. Likewise, the impact of MC on the performance of food crops is understudied. To help fill these information gaps, we conducted a controlled laboratory experiment in which we exposed lettuce, carrots, and green beans to environmentally relevant concentrations of MC-LR (0, 1, 5, and 10µg/L) via two irrigation methods (drip and spray). We used ELISA and LC-MS/MS to quantify MC-LR concentrations and in different parts of the plant (edible vs. inedible fractions), measured plant performance (e.g., size, mass, edible leaves, color), and calculated human exposure risk based on accumulation patterns. MC-LR accumulation was positively dose-dependent, with it being greater in the plants (2.2-209.2µg/kg) than in soil (0-19.4µg/kg). MC-LR accumulation varied among vegetable types, between plant parts, and between irrigation methods. MC-LR accumulation led to reduced crop growth and quality, with MC-LR persisting in the soil after harvest. Observed toxin accumulation patterns in edible fractions of plants also led to estimates of daily MC-LR intake that exceeded both the chronic reference dose (0.003µg/kg of body weight) and total daily intake guidelines (0.04µg/kg of body weight). Because the use of MC-contaminated water is common in many parts of the world, our collective findings highlight the need for guidelines concerning the use of MC-contaminated water in irrigation, as well as consumption of these crops.


Assuntos
Irrigação Agrícola , Abastecimento de Alimentos , Microcistinas/análise , Saúde Pública , Microbiologia do Solo , Verduras/microbiologia , Cromatografia Líquida , Produtos Agrícolas/microbiologia , Cianobactérias , Ensaio de Imunoadsorção Enzimática , Espectrometria de Massas em Tandem , Poluição da Água
13.
Behav Res Methods ; 48(3): 829-42, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26428910

RESUMO

Online data collection has begun to revolutionize the behavioral sciences. However, conducting carefully controlled behavioral experiments online introduces a number of new of technical and scientific challenges. The project described in this paper, psiTurk, is an open-source platform which helps researchers develop experiment designs which can be conducted over the Internet. The tool primarily interfaces with Amazon's Mechanical Turk, a popular crowd-sourcing labor market. This paper describes the basic architecture of the system and introduces new users to the overall goals. psiTurk aims to reduce the technical hurdles for researchers developing online experiments while improving the transparency and collaborative nature of the behavioral sciences.


Assuntos
Pesquisa Comportamental/métodos , Coleta de Dados/métodos , Internet , Projetos de Pesquisa , Crowdsourcing
14.
Public Hist ; 37(1): 25-38, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26281238

RESUMO

The maritime historian working as litigation support and expert witness faces many challenges, including identifying and analyzing case law associated with admiralty subjects, cultural resource management law, and general historical topics. The importance of the unique knowledge of the historian in the maritime context is demonstrated by a case study of attempts to salvage the shipwreck Atlantic, the remains of a merchant vessel built and enrolled in the United States and lost in the Canadian waters of Lake Erie in 1852.


Assuntos
Prova Pericial , História , Propriedade/legislação & jurisprudência , Navios/legislação & jurisprudência , Great Lakes Region , História do Século XIX , Ontário , Propriedade/história , Navios/história
15.
Environ Technol ; 36(9-12): 1308-18, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25515031

RESUMO

Minimal attention is paid towards the performance of the 40 million small-scale digesters which frequently operate at psychrophilic temperatures. Understanding the levels of microbial and chemical indicators at various loading rates and temperatures is useful for improving treatment efficiency and management strategies for small-scale digesters. In this study, semi-continuous anaerobic digesters were operated in replicate at four different loading rates (control, 0.3, 0.8 and 1.3 kg VS/m(3)/day) and housed in an environment that simulated seasonal change (27.5°C,10°C and 27.5°C). The results illustrate that class B quality biosolids were generated for all treatments as per guidelines from the United States Environmental Protection Agency (USEPA). The simulated seasonal change did not influence Escherichia coli or faecal coliform levels, while it did appear to have an effect upon levels of Enterococci. Reduced loading rates led to a more stable environment (in terms of pH, levels of volatile fatty acids (VFAs) and total inorganic carbonate (TIC)) as well as lower levels of indicator bacteria, but generated slightly lower biogas volumes (high--53.23 L vs. low--53.19 L) over the course of the study. The results provide important data to improve the performance of small-scale psychrophilic digesters, specifically by reducing loading rates to prevent souring during winter months.


Assuntos
Reatores Biológicos , Desinfecção , Enterococcus , Escherichia coli , Anaerobiose , Biocombustíveis/análise , Concentração de Íons de Hidrogênio , Estações do Ano , Temperatura
16.
Physiother Can ; 64(3): 245-54, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23729959

RESUMO

PURPOSE: To examine academically dishonest behaviours based on physical therapy (PT) students' current practices and educators' prior behaviours as PT students. METHOD: A Web-based questionnaire was sent to 174 students and 250 educators from the PT programme at the University of Toronto. The questionnaire gathered data on demographics as well as on the prevalence of, seriousness of, and contributing factors to academic dishonesty (AD). RESULTS: In all, 52.4% of educators and 44.3% of students responded to the questionnaire over a 6-week data-collection period. Scenarios rated the most serious were the least frequently performed by educators and students. The impact of generation on attitudes and prevalence of AD was not significant. The factors most commonly reported as contributing to AD were school-related pressure, disagreement with evaluation methods, and the perception that "everyone else does it." CONCLUSION: This study parallels the findings of similar research conducted in other health care programmes: AD does occur within the PT curriculum. AD was more prevalent in situations associated with helping peers than in those associated with personal gain. The consistency in behaviours reported across generations suggests that some forms of cheating are accepted as the social norm and may be a function of the environment.

17.
Cogn Sci ; 36(1): 150-62, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-21972923

RESUMO

Exploring how people represent natural categories is a key step toward developing a better understanding of how people learn, form memories, and make decisions. Much research on categorization has focused on artificial categories that are created in the laboratory, since studying natural categories defined on high-dimensional stimuli such as images is methodologically challenging. Recent work has produced methods for identifying these representations from observed behavior, such as reverse correlation (RC). We compare RC against an alternative method for inferring the structure of natural categories called Markov chain Monte Carlo with People (MCMCP). Based on an algorithm used in computer science and statistics, MCMCP provides a way to sample from the set of stimuli associated with a natural category. We apply MCMCP and RC to the problem of recovering natural categories that correspond to two kinds of facial affect (happy and sad) from realistic images of faces. Our results show that MCMCP requires fewer trials to obtain a higher quality estimate of people's mental representations of these two categories.


Assuntos
Emoções , Expressão Facial , Cadeias de Markov , Método de Monte Carlo , Adulto , Afeto , Algoritmos , Humanos
18.
Waste Manag Res ; 29(11): 1117-23, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21890875

RESUMO

In this study, the organic loading rate (OLR) of a high-solids anaerobic digestion (HSAD) system was increased from 3.4 to 5.0 gVS L(-1) day(-1) and reactor stability, performance and microbial community structure were determined. Laboratory simulations (3.5 L) of the full-scale process (500 dry ton year(-1)) were conducted using continuously stirred-tank mesophilic reactors. OLRs of 3.4 gVS L(-1)day(-1) (equal to the full-scale HSAD), 4.0, 4.5 and 5.0 gVS L(-1)day(-1) were evaluated. Biochemical parameters and archaeal community dynamics were measured over 42 days of steady state operation. Results showed that increasing OLR increased the amount of organic matter conversion and resulted in higher organic matter removal and volumetric methane (CH4) production (VMP) rates. The highest volatile solids (VS) removal and VMP results of 54 ± 2% and 1.4 ± 0.1 L CH4 L(-1)day(-1) were observed for 5.0 gVS L(-1) day(-1). The efficiency of reactor conversion of organic matter to CH(4) was found to be similar in all the treatments with an average value of 0.57 ± 0.07 LCH(4) gVS(-1) (removed). 16S rRNA gene terminal restriction fragment polymorphism (T-RFLP) analyses revealed that archaeal TRFs remained stable during the experiment accounting for an average relative abundance (RA) of 81 ± 1%. Archaea consistent with multiple terminal restriction fragments (TRFs) included members of the Euryarchaeota and Crenarchaeota phyla, including acetoclastic and hydrogenotrophic groups. In conclusion, this laboratory-scale study suggests that performance and stability as well as the archaeal community structure in this HSAD system was unaffected by increasing the OLR by nearly 50% and that this increase resulted in a similar increase in the amount of CH(4) gas generated.


Assuntos
Archaea/metabolismo , Reatores Biológicos/microbiologia , Eliminação de Resíduos/métodos , Esgotos/microbiologia , Anaerobiose , Archaea/genética , Cidades , Concentração de Íons de Hidrogênio , Metano/metabolismo , RNA Arqueal/genética , RNA Ribossômico 16S/genética , Esgotos/química
19.
Disabil Rehabil Assist Technol ; 6(3): 225-42, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-20929425

RESUMO

PURPOSE: This exploratory study examined the relationships between consumers' involvement in the pre-purchase decision-making process, their perceptions of feeling informed, and their degree of being satisfied with and use of assistive technology (AT). Does consumer information and participation in decision-making process lead to improved satisfaction and use of AT? METHOD: A link to an project-specific web-based survey, sent to several online disability forums and independent living centres, resulted in a sample of 145 individuals with a range of disabilities, who used a range of AT and were geographically dispersed. RESULTS: There is a significant relationship between being feeling informed and being satisfied with an AT device (F(13,278) = 27.79, p = 0.000). Feeling that personal needs were not assessed led to lower satisfaction (ß = -0.15, p < 0.07), while feeling informed resulted from a number of different factors. Lack of consumer involvement in the pre-purchase decision-making process led to somewhat greater rates of abandonment in some categories of AT (some with small n's). CONCLUSIONS: Talking with other users, auditioning the device and searching the Internet are important ways for consumers to gather information. When consumers feel informed, they are more likely to be satisfied with the AT and retain it.


Assuntos
Comportamento do Consumidor , Pessoas com Deficiência/psicologia , Equipamentos de Autoajuda/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Tomada de Decisões , Feminino , Pesquisas sobre Serviços de Saúde , Humanos , Disseminação de Informação , Internet , Masculino , Pessoa de Meia-Idade , Análise de Regressão , Estatística como Assunto , Fatores de Tempo , Estados Unidos , Adulto Jovem
20.
Bioresour Technol ; 101(12): 4362-70, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20153173

RESUMO

A co-digestion investigation was conducted using small-scale digesters in Costa Rica to optimize their ability to treat animal wastewater and produce renewable energy. Increases in methane production were quantified when swine manure was co-digested with used cooking grease in plug-flow digesters that operated at ambient temperate without mixing. The co-digestion experiments were conducted on 12 field-scale digesters (250 L each) using three replications of four treatment groups: the control (T0), which contained only swine manure and no waste oil, and T2.5, T5, and T10, which contained 2.5%, 5%, and 10% used cooking grease (by volume) combined with swine manure. The T2.5 treatment had the greatest methane (CH(4)) production (45 L/day), a 124% increase from the control, with a total biogas production of 67.3 L/day and 66.9% CH(4) in the produced biogas. Increasing the grease concentration beyond T2.5 produced biogas with a lower percentage of CH(4), and thus, did not result in any additional benefits. A batch study showed that methane production could be sustained for three months in digesters that co-digested swine manure and used cooking grease without daily inputs. The investigation proved that adding small amounts of grease to the influent is a simple way to double energy production without affecting other digester benefits.


Assuntos
Biocombustíveis/análise , Temperatura Alta , Esterco/análise , Metano/biossíntese , Óleos/química , Eliminação de Resíduos Líquidos/economia , Eliminação de Resíduos Líquidos/instrumentação , Animais , Culinária , Sulfeto de Hidrogênio/análise , Estações do Ano , Esgotos , Suínos , Fatores de Tempo
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