Impaired terrestrial and arboreal locomotor performance in the western fence lizard (Sceloporus occidentalis) after exposure to an AChE-inhibiting pesticide

We examined the effects of a commonly used AChE-inhibiting pesticide on terrestrial and arboreal sprint performance, important traits for predator avoidance and prey capture, in the western fence lizard (Sceloporus occidentalis). Lizards were exposed to carbaryl (2.5, 25, and 250 microg/g) and were raced before and 4, 24, and 96 h after dosing. In the terrestrial setting, exposure to low concentrations of carbaryl had stimulatory effects on performance, but exposure to the highest concentration was inhibitory. No stimulatory effects of carbaryl were noted in the arboreal environment and performance in lizards was reduced after exposure to both the medium and highest dose of carbaryl. Our findings suggest that acute exposure to high concentrations of carbaryl can have important sublethal consequences on fitness-related traits in reptiles and that arboreal locomotor performance is a more sensitive indicator of AChE-inhibiting pesticide poisoning than terrestrial locomotor performance.     

Macroinvertebrate Assemblages on Woody Debris and Their Relations with Environmental Variables in the Lower Sacramento and San Joaquin River Drainages, California

Data from 25 sites were used to evaluate associations between macroinvertebrate assemblages on large woody debris (snags) and environmental variables in the lower San Joaquin and Sacramento River drainages in California as part of the U.S. Geological Survey's National Water Quality Assessment Program. Samples were collected from 1993 to 1995 in the San Joaquin River drainage and in 1996 and 1997 in the Sacramento River drainage. Macroinvertebrate taxa were aggregated to the family (or higher) level of taxonomic organization, resulting in 39 taxa for analyses. Only the 31 most common taxa were used for two-way indicator species analysis (TWINSPAN) and canonical correspondence analysis (CCA). TWINSPAN analysis defined four groups of snag samples on the basis of macroinvertebrate assemblages. Analysis of variance identified differences in environmental and biotic characteristics among the groups. These results combined with the results of CCA indicated that mean dominant substrate type, gradient, specific conductance, water temperature, percentage of the basin in agricultural land use, percentage of the basin in combined agricultural and urban land uses, and elevation were important factors in explaining assemblage structure. Macroinvertebrate assemblages on snags may be useful in family level bioassessments of environmental conditions in valley floor habitats.     

Simulating Unstressed Crop Development and Growth Using the Unified Plant Growth Model (UPGM)

Since initial development of the EPIC model in 1989, the EPIC plant growth component has been incorporated into other erosion and crop management models (e.g., WEPS, WEPP, SWAT, ALMANAC, and GPFARM) and subsequently modified to meet research objectives of the model developers. This has resulted in different versions of the same base plant growth component. The objectives of this study are the following: (1) describe the standalone Unified Plant Growth Model (UPGM), initially derived from the WEPS plant growth model, to be used for merging enhancements from other EPIC-based plant growth models; and (2) describe and evaluate new phenology, seedling emergence, and canopy height sub-models derived from the Phenology Modular Modeling System (PhenologyMMS V1.2) and incorporated into UPGM. A 6-year (2005–2010) irrigated maize (Zea mays L.) study from northeast Colorado was used to calibrate and evaluate UPGM running both the original (i.e., based on WEPS) and new phenology, seedling emergence, and canopy height sub-models. Model statistics indicated the new sub-models usually resulted in better simulation results than the original sub-models. For example when comparing original and new sub-models, respectively, for predicting canopy height, the root mean square error (RMSE) was 53.7 and 40.7 cm, index of agreement (d) was 0.84 and 0.92, relative error (RE) was 26.0 and ?1.26 %, and normalized objective function (NOF) was 0.47 and 0.33. The new sub-models predict leaf number (old sub-models do not), with mean values for 4 years of 2.43 leaves (RMSE), 0.78 (d), 18.38 % (RE), and 0.27 (NOF). Simulating grain yield, final above ground biomass, and harvest index showed little difference when running the original or new sub-models. Both the new phenology and seedling emergence sub-models respond to varying water deficits, increasing the robustness of UPGM for more diverse environmental conditions. Future research will continue working to incorporate existing enhancements from other EPIC-based plant growth models to unify them into one model such as multispecies competition and N cycling.     

Economics of Coke Oven Charging Controls

This study was undertaken to determine which of several alternative air pollution abatement systems affords the most economical solution to the control of atmospheric emissions during the charging of coal into by-product coke ovens. The study was limited to the consideration of existing by-product batteries, and the assumption was made that no coking plant has the alternative to do nothing nor will the plant choose to delay abatement through legal procedures. The data indicate that a jumper pipe installation with a new larry car provides the most economical control.     

Design and Verification of a Programmable Gas Dispensing System for Exposing Plants to Dynamic Concentrations of Air Pollutants

Abstract

Landfills represent a source of distributed emissions source over an irregular and heterogeneous surface. In the method termed “Other Test Method-10” (OTM-10), the U.S. Environmental Protection Agency (EPA) has proposed a method to quantify emissions from such sources by the use of vertical radial plume mapping (VRPM) techniques combined with measurement of wind speed to determine the average emission flux per unit area per time from nonpoint sources. In such application, the VRPM is used as a tool to estimate the mass of the gas of interest crossing a vertical plane. This estimation is done by fitting the field-measured concentration spatial data to a Gaussian or some other distribution to define a plume crossing the vertical plane. When this technique is applied to landfill surfaces, the VRPM plane may be within the emitting source area itself. The objective of this study was to investigate uncertainties associated with using OTM-10 for landfills. The spatial variability of emission in the emitting domain can lead to uncertainties of –34 to 190% in the measured flux value when idealistic scenarios were simulated. The level of uncertainty might be higher when the number and locations of emitting sources are not known (typical field conditions). The level of uncertainty can be reduced by improving the layout of the VRPM plane in the field in accordance with an initial survey of the emission patterns. The change in wind direction during an OTM-10 testing setup can introduce an uncertainty of 20% of the measured flux value. This study also provides estimates of the area contributing to flux (ACF) to be used in conjunction with OTM-10 procedures. The estimate of ACF is a function of the atmospheric stability class and has an uncertainty of 10–30%.     

Research and Evaluation of Organic Hazardous Air Pollutant Source Emission Test Methods

Abstract

Title III of the Clean Air Act Amendments of 1990 has increased the need for well defined and tested stationary source emission sampling and analysis methods. The Methods Branch of the Air Measurements Research Division of U.S. EPA's Office of Research and Development is responsible for a major methods development and evaluation program intended to help fill that need. This paper summarizes recent developments from several of the component projects of that program. Primary emphasis is placed on status and references for methods for organic hazardous air pollutants, such as phosgene, methanol, chloroform, acetonitrile, isocyanates, aldehydes, halogenated organics, non-halogenated organics, and volatile organic material     

Pilot-Scale Evaluation of an Incinerability Ranking System for Hazardous Organic Compounds

The U.S. Environmental Protection Agency’s (EPA) hazardous waste incinerator performance standards specify a minimum destruction and removal efficiency (DRE) for principal organic hazardous constituents (POHCs) designated in the incinerator waste feed. In the past, selection of appropriate POHCs for incinerator trial burns has been based largely on their heats of combustion. Attempting to improve upon this approach, the University of Dayton Research Institute (UDRI), under contract to the EPA Risk Reduction Engineering Laboratory, has developed a thermal stability-based ranking of compound "incinerability". The subject study was conducted to evaluate the laboratory-developed ranking system in a pilot-scale incinerator.

Mixtures of POHCs, spanning the ranking scale from most- to least-difficult to destroy (Class 1 to Class 7, respectively), were prepared and combined with a clay-based sorbent matrix. These mixtures were then fed into the rotary kiln incineration system at the U.S. EPA Incineration Research Facility (IRF). In a series of five tests, the following conditions were evaluated: baseline/ typical operation; thermal failure (quenching); mixing failure (overcharging); matrix failure (low feed H/CI ratio); and a worst-case combination of the three failure modes.

Under baseline conditions, mixing failure, and matrix failure, kiln-exit DREs for each compound were comparable from test to test. Operating conditions in these 3 modes appeared to be sufficient to effect considerable destruction (greater than 99.99 percent DRE) of all compounds. As a result, separation of the highest-ranked POHCs from the lowest-ranked POHCs according to observed DRE was not possible; a correlation between POHC ranking and DRE could not be confirmed.

A correlation between predicted and observed incinerability was more evident for the thermal failure and worst-case conditions. Kiln-exit DREs for the four POHCs predicted to be most stable (those in Classes 1 and 2) ranged from 99% to 99.99% under these conditions, and were generally lower than DREs for the POHCs predicted to be more easily destroyed. Statistically significant correlations above the 99 percent and 93 percent confidence intervals were identified for the thermal-failure and worst-case tests, respectively.     

Reductive dechlorination of a chlorinated solvent plume in Houston,Texas

Chlorinated solvents such as tetrachloroethene (perchloroethene, PCE) and trichloroethene (TCE) have been extensively used in various industrial applications for many years. Because neither are typically consumed through their various uses, they are often released to the environment through industrial application or disposal. Once released, PCE and TCE tend to migrate downward into groundwater, where they persist. In the current case study, cheese whey was used as a groundwater amendment to facilitate the reductive dechlorination of a chlorinated solvent plume underlying an auto dealer/repair shop in Harris County, Texas. From September 2010 to January 2014, over 32,000 gallons of cheese whey were injected into the subsurface resulting in a marked reduction in oxidation–reduction potential (ORP) and nitrate concentrations, coupled with an increase in ferrous iron concentrations. Statistical trend analyses indicate the primary contaminants, PCE and TCE, as well as the daughter product cis‐1,2‐dichloroethene (cDCE), all exhibited a positive response, as evidenced by statistically decreasing trends, and/or reversal in concentration trends, subsequent to cheese whey injections. Maximum concentrations of PCE and TCE in key test wells decreased by as much as 98.97 percent and 99.17 percent, respectively. In addition, the bacterial genus Dehalococcoides, capable of complete reduction of PCE to non‐toxic ethene, was found to be more abundant in the treatment area, as compared to background concentrations. Because cheese whey is a by‐product of the cheese making process, the cost of the product is essentially limited to transport. This study demonstrates cheese whey to be an effective groundwater amendment at a cost which is orders of magnitude lower than popular industry alternatives.     

A robust weighted EM algorithm for use-availability data

Wildlife sampling for habitat selection often combines a random background sample with a random sample of used sites, because the background sample could contain too few used sites to be informative for rare species. This approach is referred to as use-availability sampling. Two variants are considered where there is: (1) a random background sample including used and unused sites augmented with a sample of used sites, and (2) a sample of used sites augmented with a contaminated background sample, i.e. use is not recorded. A weighted estimator first proposed by Manski and Lerman (Econometrica 45(8):1977?C1988, 1977) forms the basis for our suggested approach. The weighted estimator has been shown to perform better than the usual unweighted approach with uncontaminated data and mis-specified logit models (Xie and Manski in Sociol Methods Res 17(3):283?C302, 1989). A weighted EM algorithm is developed for use with contaminated background data. We show that the weighted estimator continues to perform well with contaminated data and maintains its robustness to model mis-specification. The weighted estimator has not been previously used for use-availability sampling due to reliance on the assumption that only the intercept is biased, which is valid for a correct logit model. We show that adjusting the intercept may not eliminate the bias with an incorrect logit model. In this case, the weighted estimator is a relatively simple and effective alternative.     

OPTIMAL CONTROL OF RESERVOIR RELEASES TO MINIMIZE SEDIMENTATION IN RIVERS AND RESERVOIRS1

ABSTRACT: An optimal control methodology and computational model are developed to evaluate multi‐reservoir release schedules that minimize sediment scour and deposition in rivers and reservoirs. The sedimentation problem is formulated within a discrete‐time optimal control framework in which reservoir releases represent control variables and reservoir bed elevations, storage levels, and river bed elevations represent state variables. Constraints imposed on reservoir storage levels and releases are accommodated using a penalty function method. The optimal control model consists of two interfaced components: a one‐dimensional finite‐difference simulation module used to evaluate flow hydraulics and sediment transport dynamics, and a successive approximation linear quadratic regulator (SALQR) optimization algorithm used to update reservoir release policies and solve the augmented control problem. Hypothetical two‐reservoir and five‐reservoir networks are used to demonstrate the methodology and its capabilities, which is a vital phase towards the development of a more robust optimal control model and application to an existing multiple‐reservoir river network.