Dyan Pratt

Microbial community composition is consistent across anaerobic digesters processing wheat-based fuel ethanol waste streams.

Biochemical methane potential (BMP) assays were conducted on byproducts from dry-grind wheat-based ethanol plants amended with feedlot manure at two input ratios. Whole stillage (WST), thin stillage (TST) and wet cake (WCK) were tested alone and with 1:1 and 2:1 ratios (VS basis) of byproduct:feedlot manure in bench-scale batch reactors. The addition of manure increased both the rate and consistency of methane production in triplicate reactors. In addition, digesters co-digesting thin stillage and cattle manure at 1:1 and 2:1 stillage:manure produced 125% and 119% expected methane based on the biomethane potential of each substrate digested individually. Bacterial community analysis using universal target amplification and pyrosequencing indicated there was a numerically dominant core of 42 bacteria that was universally present in the reactors regardless of input material. A smaller-scale analysis of the archaeal community showed that both hydrogenotrophic and acetoclastic methanogens were present in significant quantities.

Livestock Mortalities Burial Leachate Chemistry after Two Years of Decomposition

A study was performed to determine the chemical composition of animal mortality leachate arising in a burial setting. Three species of livestock were used: bovine, swine and poultry. Leachate collected from lined burial pits over two years of decomposition was analyzed for major and minor ions. Livestock mortality leachate contains on average, concentrations of 12,600 mg/L of ammonium-N, 46,000 mg/L alkalinity (as bicarbonate), 2,600 mg/L chloride, 3,600 mg/L sulphate, 2,300 mg/L potassium, 1,800 mg/L sodium, 1,500 mg/L phosphorus along with relative lesser amounts of iron, calcium and magnesium. Maximum concentrations of select samples had concentrations of ammonium-N and bicarbonate up to 50% higher than these average values. The pH of the leachate was near neutral. In comparison to earthen manure storages and landfills, the strength of the leachate was 2-4 times higher.

Determination of Microbial Communities beneath Livestock Burial Sites

A ten year old livestock burial site near Pierceland, Saskatchewan was continuously cored and analyzed for microbial communities at varying depths below the soil surface by molecular methods. 16S rRNA gene targets and quantitative PCR was utilized to provide a quantitative analysis of genomes per gram of soil and cpn-60 targets were used to amplify DNA for taxonomic profiling by 454 pyrosequencing. Quantification results demonstrate a three orders of magnitude greater difference in genomes at depths within and up to two meters below the burial trench as compared to a background core. Topsoil and depths below 6 meters show similar quantities of microbes for both the core through the burial trench and the background core. A total of 5905 OTUs was found at a variety of abundances in all of the 13 core samples that were analyzed. Taxonomic analysis indicated that the overall community composition changed considerably with increasing depth, and that the burial core community was distinct from the control core at the same depth. In the burial core, organisms that are associated with phosphate accumulation, nitrogen fixation, and ammonium oxidation were found in highest abundance near the surface (up to 2.5 m), while organisms associated with sulfate reduction were concentrated just below the burial depth (4.5-4.8 m). The microbial community at the burial site (3.75 m) was dominated by anaerobic microorganisms.

A comparison of extraction systems for plant water stable isotope analysis

RATIONALE The stable isotope ratios of water (δ2 H and δ18 O values) have been widely used to trace water in plants in a variety of physiological, ecohydrological, biogeochemical and hydrological studies. In such work, the analyte must first be extracted from samples, prior to isotopic analysis. While cryogenic vacuum distillation is currently the most widely used method reported in the literature, a variety of extraction-collection-analysis methods exist. A formal inter-method comparison on plant tissues has yet to be carried out. METHODS We performed an inter-method comparison of six plant water extraction techniques: direct vapour equilibration, microwave extraction, two unique versions of cryogenic vacuum distillation, centrifugation, and high-pressure mechanical squeezing. These methods were applied to four isotopically unique plant portions (head, stem, leaf, and root crown) of spring wheat (Triticum aestivum L.). Extracted plant water was analyzed via spectrometric (OA-ICOS) and mass-based (IRMS) analysis systems when possible. Spring wheat was grown under controlled conditions with irrigation inputs of a known isotopic composition. RESULTS The tested methods of extraction yielded markedly different isotopic signatures. Centrifugation, microwave extraction, direct vapour equilibration, and high-pressure mechanical squeezing produced water more enriched in 2 H and 18 O content. Both cryogenic vacuum distillation systems and the high-pressure mechanical squeezing method produced water more depleted in 2 H and 18 O content, depending upon the plant portion extracted. The various methods also produced differing concentrations of co-extracted organic compounds, depending on the mode of extraction. Overall, the direct vapor equilibration method outperformed all other methods. CONCLUSIONS Despite its popularity, cryogenic vacuum distillation was outperformed by the direct vapor equilibration method in terms of limited co-extraction of volatile organic compounds, rapid sample throughput, and near instantaneous returned stable isotope results. More research is now needed with other plant species, especially woody plants, to see how far the findings from this study could be extended.

Influence of Mass Burial of Animal Carcasses on the Types and Quantities of Microorganisms within a Burial Site

Microbial communities were characterized through a depth of 10 m in and near an eight-year-old burial site that was implemented as a control measure for cases of chronic wasting disease among wild elk. Quantitative PCR based on the 16S rRNA-encoding gene showed that the burial trench had significantly (2 to 5 orders of magnitude) more bacterial 16S rRNA-encoding genes g-1 soil within and up to 2 m below the burial site compared to a nonburial control core sample at the same depths. Topsoil and depths below the burial site (>6 m) showed similar quantities of 16S rRNA genes for both cores. Furthermore, when microbial communities were examined by cpn60 universal target amplification and pyrosequencing, 5825 operational taxonomic units (OTU) were found at a variety of abundances in all of the 13 core samples that were analyzed. Taxonomic analysis indicated that the overall community composition changed considerably with increasing depth, and that the burial core community was distinct from that of the control core at all depths. Organisms associated with phosphate accumulation, nitrogen fixation, and ammonium oxidation were found in highest abundance near the surface of the burial core (up to 2.5 m), while organisms associated with ammonification were found at the burial depth, consistent with an increase in ammonium concentration in pore water. Sequences from organisms associated with dissimilatory metal reduction were concentrated just below the burial depth (4.5 to 5.5 m). Anaerobic microorganisms dominated the microbial community at the burial site (3.75 m). The approaches described in this study provided distinct sequences that can be used to develop molecular assays for organism tracking and overall fingerprinting of microbes associated with burial sites. These data can be helpful in site evaluation and may help in the selection of future burial sites.

A portable experimental hillslope for frozen-ground studies

Frozen ground hydrological effects on runoff, storage and release have been observed in the field and tested in numerical models, but few physical models of frozen slopes (at scales from 1-15 m) exist partly because the design of such an experiment requires new engineering design for realistic whole-slope freezing and physical model innovation. Here we present a new freezable tilting hillslope physical model for hydrological system testing under a variety of climate conditions with the ability to perform multiple (up to 20 per year) freeze/thaw cycles. The 4 by 2 m hillslope is mobile and tiltable based on a modified tri-axle 4.88 m (16’) dump trailer to facilitate testing multiple configurations. The system includes controllable boundary conditions on all surfaces; examples of side and base flow boundary conditions include permeable membranes, impermeable barriers, semi-permeable configurations as well as constant head conditions. To simulate cold regions and to freeze the hillslope in a realistic and controlled manner, insulation and a removable freezer system are incorporated onto the top boundary of the hillslope. The freezing system is designed to expedite the freezing process by the addition of a 10,130 KJ (9,600 BTU) refrigeration coil to the top-center of the insulated ceiling. Center placement provides radial freezing of the hillslope in a top-down fashion, similar to what natural systems encounter in the environment. The perimeter walls are insulated with 100 mm of spray-foam insulation, while the base of the hillslope is not insulated to simulate natural heat fluxes beneath the frozen layer of soil. Our preliminary testing shows that covers can be frozen down to -10°C in approximately 7 days, with subsequent thaw on a similar timeframe.

Livestock Mortalities Burial Leachate Chemistry: The First Nine Months

A study was performed to determine the leachate chemistry from five livestock mortalities burial pits. Three species were used in this study, poultry, swine and bovine. Leachate chemistry was measured five times over a period of nine months. It was found that the chemical composition and concentrations of the leachate varies slightly by species but in general follows the same trend over the time period. Ammonium and bicarbonate are the major anions and cations respectively. Bovine leachate showed the highest values for ammonium and bicarbonate at 992 meq/L (3 months) and 875 meq/L (9 months) respectively. .