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Nitrate is a major agricultural pollutant found in drainage waters. Immature yard-waste compost was selected as a filter media to study its feasibility for removing nitrate from drainage water. Different operation parameters were tested to examine the denitrification efficiency, including the amounts of compost packed in columns, the flow rate, and the compost storage periods. The experimental results suggested that hydraulic retention time was the major factor to determine the extent of nitrate removal, although the amount of compost packed could also contribute to the nitrate removal efficiency. The effluent nitrate concentration increased as the flow rate decreased, and the compost column reduced nitrate concentrations from 20mg/L to less than 5mg/L within 1.5h. The solution pH increased at the onset of experiment because of denitrification, but stabilized at a pH of about 7.8, suggesting that the compost had a buffering capacity to maintain a suitable pH for denitrification. Storing compost under air-dried conditions may diminish the extent nitrate removed initially, but the effects were not apparent after longer applications. It appeared that immature yard-waste compost may be a suitable material to remove nitrate from tile drainage water because of its relatively large organic carbon content, high microbial activity, and buffering capacity. [Copyright &y& Elsevier]

An extensively instrumented compacted earthen liner was constructed at the Illinois State Geological Survey facility in Champaign, Ill. in 1987. A pond of water 0.31 m deep was maintained on top of the 7.3 m×14.6 m×0.9 m thick liner for 14 years. One of the goals of the project was to evaluate the long-term performance of a compacted earthen liner by monitoring the long-term changes in water content and density. The water content of the earthen liner showed no trend with depth or time. The liner density remained essentially constant from construction through excavation in 2002. The liner did not become fully saturated. Upon excavation of the liner, the degree of saturation was 80.0±6.3% after 14 years of ponding under a hydraulic head of 0.31 m. The results imply that properly designed and constructed earthen liners may reduce the possibility of pollutants leaching from municipal solid waste containment facilities by remaining partially saturated for years and maintaining the placement density. [ABSTRACT FROM AUTHOR]

A low-diversity microbial community, dominated by the γ-proteobacterium H alomonas sulfidaeris, was detected in samples of warm saline formation porewater collected from the Cambrian Mt. Simon Sandstone in the Illinois Basin of the North American Midcontinent (1.8 km/5872 ft burial depth, 50° C, pH 8, 181 bars pressure). These highly porous and permeable quartz arenite sandstones are directly analogous to reservoirs around the world targeted for large-scale hydrocarbon extraction, as well as subsurface gas and carbon storage. A new downhole low-contamination subsurface sampling probe was used to collect in situ formation water samples for microbial environmental metagenomic analyses. Multiple lines of evidence suggest that this H. sulfidaeris-dominated subsurface microbial community is indigenous and not derived from drilling mud microbial contamination. Data to support this includes V1- V3 pyrosequencing of formation water and drilling mud, as well as comparison with previously published microbial analyses of drilling muds in other sites. Metabolic pathway reconstruction, constrained by the geology, geochemistry and present-day environmental conditions of the Mt. Simon Sandstone, implies that H. sulfidaeris-dominated subsurface microbial community may utilize iron and nitrogen metabolisms and extensively recycle indigenous nutrients and substrates. The presence of aromatic compound metabolic pathways suggests this microbial community can readily adapt to and survive subsurface hydrocarbon migration. [ABSTRACT FROM AUTHOR]

Abstract: Recently, brine samples from the Cambrian-age Mount Simon Formation (the deepest, most inaccessible sedimentary rock formation of the Illinois Basin) and the overlying Ironton–Galesville Formation were collected as part of a major research effort evaluating the feasibility of sequestration of carbon dioxide in deep geologic formations. Halide and halide/cation ratios (especially Cl/Br and Na/Br ratios) from groundwater samples collected during this investigation suggest that the brines of the Cambrian-age strata formed by the evaporation of seawater well beyond the point of halite precipitation. The Cl/Br and Na/Br ratios, the presence of Mississippi-Valley-Type (MVT) ore mineralization in close proximity to the Illinois Basin, and the tectonic history of the region and the Illinois Basin suggest that components of ore-forming brines and perhaps crystalline basement brine are likely still present within the Mount Simon Formation. Halide and cation/halide ratio plots show that these brines have mixed with and have been diluted by subaerially evaporated seawater, seawater and dilute groundwater. Movement of brines out of the Mount Simon Formation and/or exchange with brines of other formations is constrained by the overlying, siltstone- and shale-rich Eau Claire Formation, a low-permeability layer. The most plausible interpretation of the halide and halide/cation ratio data is that the brines of the Cambrian-age strata were introduced to the Illinois Basin from outside of the basin, perhaps when the Illinois Basin was connected to the Arkoma (Oklahoma and Arkansas) and Black Warrior Basins (Alabama and Mississippi) via the Reelfoot Rift during Cambrian and early Ordovician time. In addition, the presence of some percentage of high NaCl, low Cl/Br brines from the crystalline basement is suggested given the geochemical relationships of the halide and cation/halide ratios and the tectonic history of the Illinois Basin. Finally, halide and cation/halide ratios determined by this investigation, and regional geochemical evidence and hydrogeologic modeling (by others) suggest that the brines of these strata probably were affected by regional hydrothermal activity during Permian time that was responsible for the MVT ore deposits of the Midwestern U.S. Thus, the brines of the deepest strata of the Illinois Basin constitute a different, more complex type of fluid than those found elsewhere in the basin. Halide and halide-cation ratios suggest that these deep brines are dominated by residual evaporitic brine (possibly originating as ore-forming brines) with dilution by seawater and dilute groundwater. Other components may include subaerially evaporated seawater and crystalline basement brines. [Copyright &y& Elsevier]

• Use of multiple gene amplicons to understand aquifer microbiomes. • Distinct spatiotemporal changes occur in suspended and attached microbial communities. • Each functional gene community exhibits unique spatiotemporal changes. • Different ecological processes control community and functional gene assembly. Despite the clear ecological significance of the microbiomes inhabiting groundwater and connected ecosystems, our current understanding of their habitats, functionality, and the ecological processes controlling their assembly have been limited. In this study, an efficient pipeline combining geochemistry, high-throughput FluidigmTM functional gene amplification and sequencing was developed to analyze the suspended and attached microbial communities inhabiting five groundwater monitoring wells in the Illinois Basin, USA. The dominant taxa in the suspended and the attached microbial communities exhibited significantly different spatial and temporal changes in both alpha- and beta-diversity. Further analyses of representative functional genes affiliated with N 2 fixation (nifH), methane oxidation (pmoA), and sulfate reduction (dsrB , and aprA), suggested functional redundancy within the shallow aquifer microbiomes. While more diversified functional gene taxa were observed for the suspended microbial communities than the attached ones except for pmoA , different levels of changes over time and space were observed between these functional genes. Notably, deterministic and stochastic ecological processes shaped the assembly of microbial communities and functional gene reservoirs differently. While homogenous selection was the prevailing process controlling assembly of microbial communities, the neutral processes (e.g., dispersal limitation, drift and others) were more important for the functional genes. The results suggest complex and changing shallow aquifer microbiomes, whose functionality and assembly vary even between the spatially proximate habitats and fractions. This research underscored the importance to include all the interface components for a more holistic understanding of the biogeochemical processes in aquifer ecosystems, which is also instructive for practical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

A field-scale compacted soil liner was constructed at the University of Illinois at Urbana-Champaign by the U.S. Environmental Protection Agency (USEPA) and Illinois State Geological Survey in 1988 to investigate chemical transport rates through low permeability compacted clay liners (CCLs). Four tracers (bromide and three benzoic acid tracers) were each added to one of four large ring infiltrometers (LRIs) while tritium was added to the pond water (excluding the infiltrometers). Results from the long-term transport of Br- from the localized source zone of LRI are presented in this paper. Core samples were taken radially outward from the center of the Br- LRI and concentration depth profiles were obtained. Transport properties were evaluated using an axially symmetric transport model. Results indicate that (1) transport was diffusion controlled; (2) transport due to advection was negligible and well within the regulatory limits of ksat<=1×10-7 cm/s; (3) diffusion rates in the horizontal and vertical directions were the same; and (4) small positioning errors due to compression during soil sampling did not affect the best fit advection and diffusion values. The best-fit diffusion coefficient for bromide was equal to the molecular diffusion coefficient multiplied by a tortuosity factor of 0.27, which is within 8% of the tortuosity factor (0.25) found in a related study where tritium transport through the same liner was evaluated. This suggests that the governing mechanisms for the transport of tritium and bromide through the CCL were similar. These results are significant because they address transport through a composite liner from a localized source zone which occurs when defects or punctures in the geomembrane of a composite system are present. [ABSTRACT FROM AUTHOR]

A 13-year study of tritium transport through a field-scale earthen liner was conducted by the Illinois State Geological Survey to determine the long-term performance of compacted soil liners in limiting chemical transport. Two field-sampling procedures (pressurevacuum lysimeter and core sampling) were used to determine the vertical tritium concentration profiles at different times and locations within the liner. Profiles determined by the two methods were similar and consistent. Analyses of the concentration profiles showed that the tritium concentration was relatively uniformly distributed horizontally at each sampling depth within the liner and thus there was no apparent preferential transport. A simple one-dimensional analytical solution to the advective-dispersive solute transport equation was used to model tritium transport through the liner. Modeling results showed that diffusion was the dominant contaminant transport mechanism. The measured tritium concentration profiles were accurately modeled with an effective diffusion coefficient of 6 x 10[sup -4] mm²/s, which is in the middle of the range of values reported in the literature. [ABSTRACT FROM AUTHOR]