Conestoga Rovers and Associates

Plymouth, MI, United States

Conestoga Rovers and Associates

Plymouth, MI, United States

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Tate P.T.,Conestoga Rovers and Associates | Shin W.S.,Kyungpook National University | Pardue J.H.,Louisiana State University | Jackson W.A.,Texas Tech University
Water, Air, and Soil Pollution | Year: 2012

The massive oil release from the Deep Water Horizon disaster has reemphasized the need to remediate oil impacted marshes. Due to the physically fragile nature of salt water marshes, bioremediation is often proposed as an appropriate technology and nutrient amendment is often proposed as a means of accelerating biodegradation of crude oil. However, no information is currently available concerning the efficacy of in situ nutrient amendments in Gulf Coast salt marshes. An experimental crude oil spill (142 l over 100 m2) was conducted to evaluate the efficacy of nitrogen amendment to stimulate bioremediation in a Spartina alterniflora dominated Louisiana salt marsh. A randomized complete block design with replication (n=10) was utilized to test the hypothesis that additions of fast-release ammonium nitrate (60 g N/m 2) and slow-release urea (30 gN/m 2) fertilizers could enhance biodegradation of selected crude oil components in the marsh. Crude oil degradation was monitored by analyzing sediment samples for branched and unbranched alkanes over the 180-day study period. The compound/hopane ratio was used to correct for nonbiological losses. No consistent statistically significant effect of fertilizer addition on degradation rates was observed, despite success in increasing the porewater ammonium and NaCl-extractable ammonium over the time frame of the trial. Intrinsic pseudo-first order degradation rates of alkanes in all plots were substantial (0.003-0.008 day -1). Existing, background levels of N did not appear to limit biodegradation rates in Spartinadominated salt marshes. These results suggest that nutrient amendments will not be successful in stimulation biodegradation of crude oil in these systems. © Springer Science+Business Media B.V. 2011.


Wei X.,Guangxi Medical University | Wei X.,Rush University Medical Center | Ai J.,Rush University Medical Center | Deng Y.,Rush University Medical Center | And 5 more authors.
BMC Genomics | Year: 2014

Background: High throughput transcriptomics profiles such as those generated using microarrays have been useful in identifying biomarkers for different classification and toxicity prediction purposes. Here, we investigated the use of microarrays to predict chemical toxicants and their possible mechanisms of action.Results: In this study, in vitro cultures of primary rat hepatocytes were exposed to 105 chemicals and vehicle controls, representing 14 compound classes. We comprehensively compared various normalization of gene expression profiles, feature selection and classification algorithms for the classification of these 105 chemicals into14 compound classes. We found that normalization had little effect on the averaged classification accuracy. Two support vector machine (SVM) methods, LibSVM and sequential minimal optimization, had better classification performance than other methods. SVM recursive feature selection (SVM-RFE) had the highest overfitting rate when an independent dataset was used for a prediction. Therefore, we developed a new feature selection algorithm called gradient method that had a relatively high training classification as well as prediction accuracy with the lowest overfitting rate of the methods tested. Analysis of biomarkers that distinguished the 14 classes of compounds identified a group of genes principally involved in cell cycle function that were significantly downregulated by metal and inflammatory compounds, but were induced by anti-microbial, cancer related drugs, pesticides, and PXR mediators.Conclusions: Our results indicate that using microarrays and a supervised machine learning approach to predict chemical toxicants, their potential toxicity and mechanisms of action is practical and efficient. Choosing the right feature and classification algorithms for this multiple category classification and prediction is critical. © 2014 Wei et al.; licensee BioMed Central Ltd.


Brusseau M.L.,University of Arizona | Matthieu III D.E.,University of Arizona | Carroll K.C.,University of Arizona | Mainhagu J.,University of Arizona | And 4 more authors.
Journal of Contaminant Hydrology | Year: 2013

The objective of this study was to characterize the temporal behavior of contaminant mass discharge, and the relationship between reductions in contaminant mass discharge and reductions in contaminant mass, for a very heterogeneous, highly contaminated source-zone field site. Trichloroethene is the primary contaminant of concern, and several lines of evidence indicate the presence of organic liquid in the subsurface. The site is undergoing groundwater extraction for source control, and contaminant mass discharge has been monitored since system startup. The results show a significant reduction in contaminant mass discharge with time, decreasing from approximately 1 to 0.15 kg/d over five years. Two methods were used to estimate the mass of contaminant present in the source area at the initiation of the remediation project. One was based on a comparison of two sets of core data, collected 3.5 years apart, which suggests that a significant (~ 80%) reduction in aggregate sediment-phase TCE concentrations occurred between sampling events. The second method was based on fitting the temporal contaminant mass discharge data with a simple exponential source-depletion function. Relatively similar estimates, 784 and 993 kg, respectively, were obtained with the two methods. These data were used to characterize the relationship between reductions in contaminant mass discharge (CMDR) and reductions in contaminant mass (MR). The observed curvilinear relationship exhibits a reduction in contaminant mass discharge essentially immediately upon the initiation of mass reduction. This behavior is consistent with a system wherein significant quantities of mass are present in hydraulically poorly accessible domains for which mass removal is influenced by rate-limited mass transfer. The results obtained from the present study are compared to those obtained from other field studies to evaluate the impact of system properties and conditions on mass-discharge and mass-removal behavior. The results indicate that factors such as domain scale, hydraulic-gradient status (induced or natural), and flushing-solution composition had insignificant impact on the CMDR-MR profiles and thus on underlying mass-removal behavior. Conversely, source-zone age, through its impact on contaminant distribution and accessibility, was implicated as a critical factor influencing the nature of the CMDR-MR relationship. © 2013 Elsevier B.V.


Marino D.J.,Conestoga Rovers and Associates
Journal of Toxicology and Environmental Health - Part A: Current Issues | Year: 2012

Since the early 1970s, the National Cancer Institute (NCI) and National Toxicology Program (NTP) have conducted carcinogenesis and toxicology studies on several hundred chemicals using the B6C3F1 mouse. A number of publications have examined growth, survival, and tumor incidence over time, including the impact of changes in housing and diet. However, no reports have been published to date examining the variation in organ weights over time, especially in light of reported body weight effects associated with housing and diet changes. Therefore, all available absolute and relative organ weight data for untreated control B6C3F1 mice were collected from 2-wk, 3-mo, and 15-mo NCI/NTP investigations with report dates through August 2010 in order to examine organ weight changes over time and by study type. Study data were grouped into 5-yr intervals by initiation date. Body weights in males increased over time except in 2-wk studies, while body weights in females rose through 1993 and remained constant or declined thereafter. Higher body weights were noted in individually housed mice, and in drinking water studies compared to feed or inhalation studies. Elevated organ weights were typically associated with increased body weights except that lower organ weights were evident as early as 2-wk on study with the introduction of the NTP-2000 diet in 1994. Relative organ weights decreased over time in males and females. Finally, organ weight coefficients of variation (standard deviation/mean) declined over time in 2-wk, 3-mo, and 15-mo studies, which may reflect improved data collection methods or reduced interlaboratory variability. © 2012 Copyright Taylor and Francis Group, LLC.


Marino D.J.,Conestoga Rovers and Associates
Journal of Toxicology and Environmental Health - Part A: Current Issues | Year: 2012

The Fischer 344 (F344) rat has been the standard rat strain used in toxicology studies conducted by the National Cancer Institute (NCI) and the National Toxicology Program (NTP). However, the numerous reports published to date on growth, survival, and tumor incidence have not included an overall compilation of organ weight data. Notably, dose-related organ weight effects are endpoints used by regulatory agencies to develop toxicity reference values (TRVs) for use in human health risk assessments. In addition, physiologically-based pharmacokinetic (PBPK) models, which utilize relative organ weights, are increasingly being used to develop TRVs. Because a compilation of organ weights for F344 rats could prove beneficial for TRV development and PBPK modeling, all available absolute and relative organ weight data for untreated control F344 rats were collected from NCI/NTP feed, drinking-water, and inhalation studies in order to develop age-specific distributions. Results showed that organ weights were collected more frequently at 2-wk (59 studies), 3-mo (148 studies), and 15-mo (38 studies) intervals than at other intervals and more frequently from feeding and inhalation than from drinking-water studies. Liver, right kidney, lung, heart, thymus, and brain weights were most frequently collected. From the collected data, the mean and standard deviation for absolute and relative organ weights were calculated. Findings showed age-related increases in absolute weights and decreases in relative weights for brain, liver, right kidney, lung, heart, thyroid, and right testis. The results suggest a general variability trend in absolute organ weights of brain < right testis < heart < right kidney < liver < lung < thymus < thyroid. © 2012 Copyright Taylor and Francis Group, LLC.


Marino D.J.,Conestoga Rovers and Associates
Journal of Toxicology and Environmental Health - Part A: Current Issues | Year: 2012

The B6C3F1 mouse is the standard mouse strain used in toxicology studies conducted by the National Cancer Institute (NCI) and the National Toxicology Program (NTP). While numerous reports have been published on growth, survival, and tumor incidence, no overall compilation of organ weight data is available. Importantly, organ weight change is an endpoint used by regulatory agencies to develop toxicity reference values (TRVs) for use in human health risk assessments. Furthermore, physiologically based pharmacokinetic (PBPK) models, which utilize relative organ weights, are increasingly being used to develop TRVs. Therefore, all available absolute and relative organ weight data for untreated control B6C3F1 mice were collected from NCI/NTP studies in order to develop age-specific distributions. Results show that organ weights were collected more frequently in NCI/NTP studies at 2-wk (60 studies), 3-mo (147 studies), and 15-mo (40 studies) intervals than at other intervals, and more frequently from feeding and inhalation than drinking water studies. Liver, right kidney, lung, heart, thymus, and brain weights were most frequently collected. From the collected data, the mean and standard deviation for absolute and relative organ weights were calculated. Results show age-related increases in absolute liver, right kidney, lung, and heart weights and relatively stable brain and right testis weights. The results suggest a general variability trend in absolute organ weights of brain < right testis < right kidney < heart < liver < lung < spleen < thymus. This report describes the results of this effort. © 2012 Copyright Taylor and Francis Group, LLC.


Marino D.J.,Conestoga Rovers and Associates
Toxicology Mechanisms and Methods | Year: 2012

The B6C3F1 mouse is the standard mouse strain used in National Toxicology Program (NTP) carcinogenesis studies. Over time, increased liver tumorigenesis that was correlated with elevated body weights was noted in males and females. NTP therefore replaced the NIH-07 diet with the NTP-2000 diet and returned to group housing of females as lower body weights were noted in group housed mice. However, recent studies reported study-type differences in body weights at 3 months using the NTP-2000 diet with higher weights evident in drinking water and inhalation studies compared to feed studies. Therefore, body weight and tumor incidence data were collected for untreated control mice from all 2-year NTP feed (12), drinking water (8), water gavage (6) and inhalation (10) studies that used the NTP-2000 diet in order to assess the impact of study type on body weights and tumor incidences. Results show statistically significant elevated body weights and liver tumor incidences in males and females from drinking water, water gavage and inhalation studies compared to results from feed studies. Thus, the elevated body weights and liver tumorigenesis noted in mice using the NIH-07 diet were also evident using the NTP-2000 diet, which was introduced to address body weight elevations. Given the study-type dependent effects noted, these results emphasize the importance of carefully selecting historical control data for B6C3F1 mice. Moreover, because of the association between body weight and liver tumorigenesis, these results may have implications regarding dose-level selection for carcinogenicity studies involving B6C3F1 mice based on the maximum tolerated dose. © 2012 Informa Healthcare USA, Inc.


Ferguson J.E.,Conestoga Rovers and Associates
ASABE - International Symposium on Air Quality and Waste Management for Agriculture 2010 | Year: 2010

Odor is a contaminant receiving increased attention in the agricultural industry. As residential sprawl encroaches on agricultural land and farm size increases, odor complaints are becoming more common. This paper provides an overview of odor considerations in agriculture including sampling methods, methods for mitigating odor and odor regulations. Odor continues to be a topic of interest to the United States Environmental Protection Agency (EPA) although they not federally regulated at this time. As the number of odor complaints increases, environmental exemptions for agriculture are being rescinded by local governments. The management of odor from the agricultural industry is essential. Odor regulations are varied within countries and around the world, and are much less consistent than the regulations surrounding toxic and other risk based criteria. Odor is almost always comprised of more than one compound and the synergistic effects between compounds make predicting odor strength difficult. Proper sampling and analytical techniques are required to present a representative odor profile for various operations. In the summer of 2011, the EPA anticipates publishing emission estimating methodologies for animal feeding operations, which can be used in place of expensive sampling programs to develop emission profiles. An emission profile is required to understand where improvements can best be made to eliminate or reduce odor emissions to minimize potential off-site impacts. This paper addresses various odor regulations in the United States, approved sampling procedures, sample analysis methods, air dispersion modeling, abatement strategies, and agricultural best management practices. This paper discusses the sources of odor in agriculture and how odor is quantified in industry and in regulation. A variety of odor sampling methods are discussed. The paper reviews forced choice olfactometry and explains how odor concentration is defined. Once odor is quantified, the concentration can be used in a dispersion model to predict the concentration experienced by off site receptors. This paper also provides an overview of proven odor abatement technologies including scrubbers, biofilters, and digesters. An introduction to best management practices for odor abatement including manure handling and application techniques, building ventilation, and separation distances from residents. An overview of the EPA consent decree and the status of the decree are outlined.


Lorint C.,University of Petrosani | Radulescu M.,Conestoga Rovers and Associates | Buia G.,University of Petrosani
Environmental Geochemistry and Health | Year: 2012

The current study represents a preliminary investigation made into the influence of cattle grazing in the area of a bauxite quarry (Comarnic-Poieni, Romania) on the cow milk chemistry. Weathering and surface runoff in the bauxite quarry contaminate the local chemistry of the soil, vegetation and water. During cattle transhumance, cyclic feeding patterns occur, with grazing alternating between clean pastures and the area of the quarry. Soil and water samples were collected from the contaminated area of the quarry. Raw milk samples were collected during two stages, corresponding to the periods of grazing on clean pasture and the quarry area, respectively. Based on the obtained data, the relationship between cattle grazing and the composition of milk was interpreted. Preliminary results indicated a direct correlation of increased concentration of Al in the milk, following grazing in the bauxite quarry. © 2011 Springer Science+Business Media B.V.


Wiens T.C.,Conestoga Rovers and Associates
Proceedings of Meetings on Acoustics | Year: 2013

Urban noise is an emerging nuisance issue for growing communities. The analysis method discussed herein can be used to industry's advantage. A road traffic noise model was developed by Conestoga-Rovers & Associates (CRA) to approximate the ambient community noise levels present within a 200 km2 project area. Road corridors that included highways, city streets, and country side-roads were modeled to evaluate the existing road traffic generated ambient noise environment. An acoustical model and US Department of Transportation Federal Highway Administration Traffic Noise Model calculation standard was used to account for a variety of real-world variables such as Daily Average Traffic Counts, turning counts, speed limits, road composition, elevation, road width, and traffic composition. The model generated noise contours that were used to identify areas of elevated ambient noise levels within the project area that may prove suitable for a medium-sized industrial facility. This quantification of the ambient community noise environment allowed for the identification of optimal industrial sites within the project area. Locating new facilities within urbanized areas with elevated ambient conditions promotes complementary adjacent land use and sustainable urban densification by minimizing adverse community noise impacts and reducing post-construction noise abatement costs for industry. © 2013 Acoustical Society of America.

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