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Composting swine slurries has several advantages, liquid slurries are converted to solids at lower moisture, the total volume and weight of material is reduced and the stabilized product is more easily transported off-site. Despite this, swine waste is generally stored, treated and applied in its liquid form. High-rise finishing facilities (HRFF) permit liquid slurries to be converted to solids which are partially decomposed underneath the HRFF and then finished in compost windrows. The purpose of this study was to evaluate the effect of turning frequency and ambient weather conditions on biological, physical and chemical properties of composted slurry-woodchip mixtures from HRFF. Compost trials were conducted in either fall (FT) or spring (ST) and piles were turned once or three times per week or upon compost temperature reaching 65°C. Physical, chemical and microbiological characteristics were measured over the course of 112 (FT) or 143 (ST) days of composting. Total carbon, total nitrogen (N) and inorganic N decreased in all piles. Ammonium decreased while nitrate increased in all piles (including unturned), but total N losses were greatest in piles turned more frequently during the ST. Microbial populations of nitrifiers were dominated by ammonia-oxidizing archaea (3.0×10(3)-4.2×10(6)cellsg(-1) compost) but ammonia oxidizing bacteria (below detection to 6.0×10(5)cellsg(-1) compost) varied in response to turning and compost temperature; denitrifiers were present in high concentrations throughout the process. Swine HRFF materials composted well in windrows regardless of turning frequency and despite significant differences in starting materials and low initial C/N. Volume reduction, low moisture and low readily degradable organic matter suggest that the finished compost would have lower transportation costs and should provide value as a soil conditioner.

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The inability to incorporate manure into permanent pasture leads to the concentration of nutrients near the soil surface with the potential to be transported off site by runoff water. In this study, we used rainfall simulations to examine the effect of broiler chicken (Gallus gallus domesticus) litter application method and the runoff timing on nutrient and E. coli losses from tall fescue (Festuca arundinacea Schreb.) pasture on a Hartsells sandy loam soil (fine-loamy, siliceous, subactive, thermic Typic Hapludults)) in Crossville, AL. Treatments included two methods of litter application (surface broadcast and subsurface banding), commercial fertilizer, and control. Litter was applied at a rate of 8.97 Mg ha(-1). Treatments were assigned to 48 plots with four blocks (12 plots each) arranged in a randomized complete block design to include three replications in each block. Simulated rainfall was applied to treatments as follows: Day 1, block 1 (runoff 1); Day 8, block 2 (runoff 2); Day 15, block 3 (runoff 3); and Day 22, block 4 (runoff 4). Total phosphorus (TP), inorganic N, and Escherichia coli concentrations in runoff from broadcast litter application were all significantly greater than from subsurface litter banding. The TP losses from broadcast litter applications averaged 6.8 times greater than those from subsurface litter applications. About 81% of the runoff TP was in the form of dissolved reactive phosphorus (DRP) for both litter-application methods. The average losses of NO(3)-N and total suspended solids (TSS) from subsurface banding plots were 160 g ha(-1) and 22 kg ha(-1) compared to 445 g ha(-1) and 69 kg ha(-1) for the broadcast method, respectively. Increasing the time between litter application and the first runoff event helped decrease nutrient and E. coli losses from surface broadcast litter, but those losses generally remained significantly greater than controls and subsurface banded, regardless of runoff timing. This study shows that subsurface litter banding into perennial grassland can substantially reduce nutrient and pathogen losses in runoff compared to the traditional surface-broadcast practice.

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Escherichia coli is a commonly used indicator organism for detecting the presence of fecal-borne pathogenic microorganisms in water supplies. The importance of E. coli as an indicator organism has led to numerous studies looking at cell properties and transport behavior of this microorganism. In many of these studies, however, only a single strain of E. coli was used even though research has shown that significant genetic variability exists among different strains of E. coli. If this genetic diversity results in differences in cell properties that affect transport, different strains of E. coli may exhibit different rates of transport in the environment. Therefore, the objectives of our study were to investigate the variability in surface characteristics and transport behavior of E. coli isolates obtained from six different sources: beef cattle, dairy cattle, horse, human, poultry, and wildlife. Cell properties such as electrophoretic mobility, cell size and shape, hydrophobicity, charge density, and extracellular polymeric substance composition were measured for each isolate. In addition, the transport behavior of each isolate was assessed by measuring transport through 10-cm packed beds of clean quartz sand. Our results show a large diversity in cell properties and transport behavior for the different E. coli isolates. This diversity in transport behavior must be taken into account when making assessments of the suitability of using E. coli as an indicator organism for specific pathogenic microorganisms in groundwater environments as well as modeling the movement of E. coli in the subsurface.

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AIMS: To investigate the processes controlling the transport of Mycobacterium avium subsp. paratuberculosis (Map) through aquifer materials. METHODS AND RESULTS: We measured two important surface characteristics known to affect bacterial attachment to sediment surfaces: surface charge and hydrophobicity. We then measured the transport of Map through laboratory columns packed with aquifer sand with varying ionic strength solutions and sediment surface charge. We found that Map has a strong negative charge and is highly hydrophobic and that the transport of Map through positively charged Fe-coated sands was reduced compared with transport through negatively charged clean quartz sand, although Map transport for all treatments was low compared with the transport behaviour reported in the literature for other bacteria. CONCLUSIONS: Our results suggest that the potential for groundwater contamination by Map is low; however, the organism may remain bound to the soil near the surface where it can be ingested by grazing animals or be released during run off events. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study looking at the surface characteristics and transport behaviour of Map through aquifer materials and therefore provides important information for understanding the movement of Map in the environment.

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The influence of bacterial starvation on cell transport has been examined using two Escherichia coli isolates: one from human (HU) and one from dairy cattle (DC). To better understand the fate of starved bacteria, experiments were conducted in a packed bed column using cells that had been incubating at room temperature without nutrients for 6, 12, and 18h, as well as cells, which had not been starved (referred to as time zero). Complimentary cell characterization techniques were conducted to evaluate the hydrophobicity, mobility, size, and surface charge density of the cells at the conditions considered. It was observed that non-starved HU cells were more adhesive than starved HU cells. This behavior is attributed to the relatively high hydrophobicity of the starved cells, which resulted from greater extracellular polymeric substance (EPS) presence. Non-starved DC cells were also the most adhesive whereas 18h starved cells were the least adhesive, although cell characterization results did not correlate to transport trends like HU cells. For both isolates, the cells after 6h of starvation showed high levels of sugar relative to protein in the EPS. Additionally, following 6h of starvation, the cells did not follow expected transport trends as anticipated from the cellular characterization. Our results suggest transport behavior of environmental E. coli isolates differs in terms of isolate host and starvation conditions. Possible mechanisms responsible for this are changes in key cell surface characteristics and synthesis of starvation-induced proteins. This study highlights the importance of consistency in bacterial preparation for experimental studies and has considerable implications for future evaluation and prediction of E. coli fate in subsurface environments.

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AIMS: To evaluate the survival of Campylobacter jejuni relative to that of Escherichia coli in groundwater microcosms varying in nutrient composition. METHODS AND RESULTS: Studies were conducted in groundwater and deionized water incubated for up to 470 days at 4 degrees C. Samples were taken for culturable and total cell counts, nutrient and molecular analysis. Die-off in groundwater microcosms was between 2.5 and 13 times faster for C. jejuni than for E. coli. Campylobacter jejuni had the lowest decay rate and longest culturability in microcosms with higher dissolved organic carbon (4 mg l(-1)). Escherichia coli survival was the greatest when the total dissolved nitrogen (12.0 mg l(-1)) was high. The transition of C. jejuni to the coccoid stage was independent of culturability. CONCLUSION: The differences in the duration of survival and response to water nutrient composition between the two organisms suggest that E. coli may be present in the waters much longer and respond to water composition much differently than C. jejuni. SIGNIFICANCE AND IMPACT OF THE STUDY: The data from these studies would aid in the evaluation of the utility of E. coli as an indicator of C. jejuni. This study also provided new information about the effect of nutrient composition on C. jejuni viability.

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Data from a large-scale canal-drawdown test were used to estimate the specific yield (sy) of the Biscayne Aquifer, an unconfined limestone aquifer in southeast Florida. The drawdown test involved dropping the water level in a canal by about 30 cm and monitoring the response of hydraulic head in the surrounding aquifer. Specific yield was determined by analyzing data from the unsteady portion of the drawdown test using an analytical stream-aquifer interaction model (Zlotnik and Huang 1999). Specific yield values computed from drawdown at individual piezometers ranged from 0.050 to 0.57, most likely indicating heterogeneity of specific yield within the aquifer (small-scale variation in hydraulic conductivity may also have contributed to the differences in sy among piezometers). A value of 0.15 (our best estimate) was computed based on all drawdown data from all piezometers. We incorporated our best estimate of specific yield into a large-scale two-dimensional numerical MODFLOW-based ground water flow model and made predictions of head during a 183-day period at four wells located 337 to 2546 m from the canal. We found good agreement between observed and predicted heads, indicating our estimate of specific yield is representative of the large portion of the Biscayne Aquifer studied here. This work represents a practical and novel approach to the determination of a key hydrogeological parameter (the storage parameter needed for simulation and calculation of transient unconfined ground water flow), at a large spatial scale (a common scale for water resource modeling), for a highly transmissive limestone aquifer (in which execution of a traditional pump test would be impractical and would likely yield ambiguous results). Accurate estimates of specific yield and other hydrogeological parameters are critical for management of water supply, Everglades environmental restoration, flood control, and other issues related to the ground water hydrology of the Biscayne Aquifer.

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The injection of bacteria in the subsurface has been identified as a potential method for in situ cleanup of contaminated aquifers. For high bacterial loadings, the presence of previously deposited bacteria can result in decreased deposition rates--a phenomenon known as blocking. Miscible displacement experiments were performed on short sand columns (approximately 5 cm) to determine how bacterial deposition on positively charged metal-oxyhydroxide-coated sands is affected by the presence of previously deposited bacteria. Approximately 8 pore volumes of a radiolabeled bacterial suspension at a concentration of approximately 1 x 10(9) cells ml-1 were introduced into the columns followed by a 2-pore-volume flush of cell-free buffer. It was found that the presence of Al- and Fe-coated sand increased both deposition rates and maximum fractional surface coverage of bacteria on the sediment surfaces. The effect of grain size on maximum bacterial retention capacity, however, was not significant. Decreasing ionic strength from 10(-1) to 10(-2) M KCl resulted in noticeable decreases in sticking efficiency (alpha) and maximum surface coverage (thetamax) for clean silica sand--results consistent with DLVO theory. In columns containing positively charged Al- and Fe-coated sands, however, changes in alpha and thetamax due to decreasing ionic strength were minimal. These findings demonstrate the importance of geochemical controls on the maximum bacterial retention capacity of sands.

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A series of microcosm experiments was performed using serial dilutions of a sewage microbial community to inoculate a set of batch cultures in sterile sewage. After inoculation, the dilution-defined communities were allowed to regrow for several days and a number of community attributes were measured in the regrown assemblages. Based upon a set of numerical simulations, community structure was expected to differ along the dilution gradient; the greatest differences in structure were anticipated between the undiluted-low-dilution communities and the communities regrown from the very dilute (more than 10(-4)) inocula. Furthermore, some differences were expected among the lower-dilution treatments (e.g., between undiluted and 10(-1)) depending upon the evenness of the original community. In general, each of the procedures used to examine the experimental community structures separated the communities into at least two, often three, distinct groups. The groupings were consistent with the simulated dilution of a mixture of organisms with a very uneven distribution. Significant differences in community structure were detected with genetic (amplified fragment length polymorphism and terminal restriction fragment length polymorphism), physiological (community level physiological profiling), and culture-based (colony morphology on R2A agar) measurements. Along with differences in community structure, differences in community size (acridine orange direct counting), composition (ratio of sewage medium counts to R2A counts, monitoring of each colony morphology across the treatments), and metabolic redundancy (i.e., generalist versus specialist) were also observed, suggesting that the differences in structure and diversity of communities maintained in the same environment can be manifested as differences in community organization and function.

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