Growth and damping of interfacial waves on a diffuse interface

The resonant interaction of surface and internal waves produces a nonlinear mechanism for energy transfer among wave components in oceans, lakes, and estuaries. In many field situations, the stratification may be well approximated by a two-layer fluid with a diffuse interface. The growth and damping rates of sub-harmonic interfacial waves generated by a surface wave through a three-wave resonant interaction are measured in the laboratory. These measurements are compared with theoretical predictions. A diffuse interface reduces the damping rate and increases the growth rate. The predicted growth rate provides excellent comparison with the laboratory measurements. The inclusion of the effects of a diffuse interface significantly improve the comparison.     

Thermally enhanced hydrolysis for treatment of pesticides and explosives

Thermally enhanced hydrolysis of halogenated alkanes such as 1,1,1‐trichlorethane has become a proven method of in situ soil and groundwater remediation. Electrical resistance heating is commonly used to heat soil and groundwater to accelerate the rate of hydrolysis. This article provides practical information to extend the hydrolysis remediation toolkit to include treatment of common pesticides and explosives. Sites with comingled volatile compounds, pesticides, and/or explosives can also be treated via a single solution.     

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.     

Application of a benthic observed/expected-type model for assessing Central Appalachian streams influenced by regional stressors in West Virginia and Kentucky

Stream bioassessments rely on taxonomic composition at sites compared with natural, reference conditions. We developed and tested an observed/expected (O/E) predictive model of taxonomic completeness and an index of compositional dissimilarity (BC index) for Central Appalachian streams using combined macroinvertebrate datasets from riffle habitats in West Virginia (WV) and Kentucky (KY). A total of 102 reference sites were used to calibrate the O/E model, which was then applied to assess over 1,200 sites sampled over a 10-year period. Using an all subsets discriminant function analysis (DFA) procedure, we tested combinations of 14 predictor variables that produced DF and O/E models of varying performance. We selected the most precise model using a probability of capture at >0.5 (O/E _0.5, SD?=?0.159); this model was constructed with only three simple predictor variables—Julian day, latitude, and whether a site was in ecoregion 69a. We evaluated O/E and BC indices between reference and test sites and compared their response to regional stressors, including coal mining, residential development, and acid deposition. The Central Appalachian O/E and BC indices both showed excellent discriminatory power and were significantly correlated to a variety of regional stressors; in some instances, the BC index was slightly more sensitive and responsive than the O/E _0.5 model. These indices can be used to supplement existing bioassessment tools crucial to detecting and diagnosing stream impacts in the Central Appalachian region of WV and KY.     

Comparison of precipitation chemistry measurements obtained by the Canadian Air and Precipitation Monitoring Network and National Atmospheric Deposition Program for the period 1995–2004

Precipitation chemistry and depth measurements obtained by the Canadian Air and Precipitation Monitoring Network (CAPMoN) and the US National Atmospheric Deposition Program/National Trends Network (NADP/NTN) were compared for the 10-year period 1995–2004. Colocated sets of CAPMoN and NADP instrumentation, consisting of precipitation collectors and rain gages, were operated simultaneously per standard protocols for each network at Sutton, Ontario and Frelighsburg, Ontario, Canada and at State College, PA, USA. CAPMoN samples were collected daily, and NADP samples were collected weekly, and samples were analyzed exclusively by each network’s laboratory for pH, H^?+?, Ca^2?+?, Mg^2?+?, Na^?+?, K^?+?, $\text{NH}_{4}^{+}$ , Cl^???, $\text{NO}_{3}^{-}$ , and $\text{SO}_{4}^{2-}$ . Weekly and annual precipitation-weighted mean concentrations for each network were compared. This study is a follow-up to an earlier internetwork comparison for the period 1986–1993, published by Alain Sirois, Robert Vet, and Dennis Lamb in 2000. Median weekly internetwork differences for 1995–2004 data were the same to slightly lower than for data for the previous study period (1986–1993) for all analytes except $\text{NO}_{3}^{-}$ , $\text{SO}_{4}^{2-}$ , and sample depth. A 1994 NADP sampling protocol change and a 1998 change in the types of filters used to process NADP samples reversed the previously identified negative bias in NADP data for hydrogen-ion and sodium concentrations. Statistically significant biases (α = 0.10) for sodium and hydrogen-ion concentrations observed in the 1986–1993 data were not significant for 1995–2004. Weekly CAPMoN measurements generally are higher than weekly NADP measurements due to differences in sample filtration and field instrumentation, not sample evaporation, contamination, or analytical laboratory differences.     

Salmonella survival in manure-treated soils during simulated seasonal temperature exposure

Addition of animal manure to soil can provide opportunity for Salmonella contamination of soil, water, and food. This study examined how exposure of hog manure-treated loamy sand and clay soils to different simulated seasonal temperature sequences influenced the length of Salmonella survival. A six-strain cocktail of Salmonella serovars (Agona, Hadar, Heidelberg, Montevideo, Oranienburg, and Typhimurium) was added to yield 5 log cfu/g directly to about 5 kg of the two soils and moisture adjusted to 60 or 80% of field capacity (FC). Similarly, the Salmonella cocktail was mixed with fresh manure slurry from a hog nursery barn and the latter added to the two soils at 25 g/kg to achieve 5 log cfu/g Salmonella. Manure was mixed either throughout the soil or with the top kilogram of soil and the entire soil volume was adjusted to 60 or 80% FC. Soil treatments were stored 180 d at temperature sequences representing winter to summer (-18, 4, 10, 25 degrees C), spring to summer (4, 10, 25, 30 degrees C), or summer to winter (25, 10, 4, -18 degrees C) seasonal periods with each temperature step lasting 45 d. Samples for Salmonella recovery by direct plating or enrichment were taken at 0, 7, and 15 d post-inoculation and thereafter at 15-d intervals to 180 d. Salmonella numbers decreased during application to soil and the largest decreases occurred within the first week. Higher soil moisture, manure addition, and storage in the clay soil increased Salmonella survival. Salmonella survived longest (> or = 180 d) in both soils during summer-winter exposure but was not isolated after 160 d from loamy sand soil exposed to other seasonal treatments. For all but one treatment decimal reduction time (DRT45d) values calculated from the first 45 d after application were < or = 30 d and suggested that a 30-d delay between field application of manure in the spring or fall and use of the land would provide reasonable assurance that crop and animal contamination by Salmonella would be minimized.     

The mobility of thiobencarb and fipronil in two flooded rice-growing soils

The mobility of the rice pesticides thiobencarb (S-[(4-chlorophenyl) methyl] diethylcarbamothioate) and fipronil ([5-amino-3-cyano-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl]pyrazole) were investigated in the glasshouse under flooded conditions using two Australian rice-growing soils. When using leakage rates of 10 mm day(-1), less than 20% of applied thiobencarb and fipronil remained in the water column after 10 days due to rapid transfer to the soil phase. Up to 70% and 65% of the applied thiobencarb and fipronil, respectively, were recovered from the 0-1 cm layer of soils. Only 5-7% of each pesticide was recovered from the 1-2 cm layer, and less than 2% was recovered from each 1 cm layer in the 2-10 cm region of the soils. Analysis of the water leaking from the base of the soil cores showed between 5-10% of the applied thiobencarb and between 10-20% of the applied fipronil leaching from the soil cores. The high levels of pesticide in the effluent was attributed to preferential flow of pesticide-laden water via soil macropores resulting from the wetting and drying process, worm holes and root channels.     

Role of protein, amino acids, and enzyme activity on odor production from anaerobically digested and dewatered biosolids.

The main objective of this research was to test the hypothesis that bioavailable protein and, more specifically, the sulfur-containing amino acids within the protein, can be degraded by proteolytic enzymes to produce odor-causing compounds--mainly volatile sulfur compounds (VSCs)--during biosolids storage. To achieve these objectives, samples of digester effluent and cake solids were collected at 11 different wastewater treatment plants in North America, and the samples were analyzed for protein and amino acid content and general protein-degrading enzyme activity. At the same time, cake samples were stored using headspace bottles, the concentration of VSCs were measured using gas chromatography, and olfactometry measurements were made by a trained odor panel. The results showed that the bound cake protein content and methionine content was well-correlated with VSC production and the detection threshold measured by the odor panel.     

A spectroscopic study of the bromination of the endocrine disruptor ethynylestradiol

Bromination of ethynylestradiol (EE2) was studied using fluorescence and conventional and stopped-flow absorbance spectroscopy. EE2 transformations in the presence of bromine were determined to proceed through sequential reactions. The first step is very rapid and results in the formation of a brominated cyclohexadienone that is susceptible to reduction but in oxidative conditions it undergoes a transformation into monobromo-EE2 in a first-order OH- -accelerated reaction. The transformation from monobromo-EE2 to dibromo-EE2 follows a similar mechanism. The rates of reactions of bromine-substituted EE2 species are orders of magnitude lower than that of the parent compound indicating that these species can persist in conditions typical for water treatment operations.