Determining Capture Zones for Three-Dimensional, Heterogeneous, Anisotropic Aquifers by Monte Carlo Analysis, Jon Paul Jones, Department of Geology and Geological Engineering, Box 8358, University of North Dakota, Grand Forks, ND 58202-8358. [Advisor: Dr. Philip J. Gerla, Department of Geology and Geological Engineering] M.S. December 1998. Ph.D. Program, University of Waterloo, Canada

Most methods of delineating capture zones for pump-and-treat remedial design and wellhead protection assume a two-dimensional, homogeneous aquifer. Real aquifers, however, are three-dimensional and heterogeneous, thereby introducing uncertainty in capture zone analysis. This study used a Monte Carlo analysis of three sets of statistical parameters defining aquifer heterogeneity. Each set had a difference variance for the mean ln(K), which varied among the sets by a factor of four. The ensemble means of the capture zones for each set were estimated from 120 realizations. Realizations of the hydraulic conductivity fields were generated using the method of fast Fourier transforms and incorporated into a confined, 128 m long by 64 m wide grid that included sufficient vertical layers to maintain the vertical correlation length. The U.S. Geological Survey MODFLOW code coupled with MODPATH was used to simulate the capture zones surrounding a pumping well within a simple flow system defined by constant head boundaries on the narrow edges of the grid. Mapping the capture zones for many aquifer realizations with similar stochastic properties provided the data required to construct 1%, 80%, and 90% quantile intervals. These figures begin to show how heterogeneity reduces the size of the capture zones estimated for statistically homogeneous aquifers.

Effects of Bait Fish on Prairie Wetland Ecosystems, Kyle D. Zimmer, Department of Zoology, North Dakota State University, Fargo, ND 58105. [Advisor: Malcolm Butler, Department of Zoology] Ph.D. expected May 2001. Currently Graduate Research Fellow, Department of Biology, NDSU.

Fish populations affect biotic and abiotic components of aquatic systems, and may influence aquatic ecosystem structure. Fathead minnows are naturally found in some prairie wetlands, but intentional stocking and landscape alterations have likely increased the number of wetlands supporting a minnow population. My objectives are to quantify effects of fathead minnows on restored and natural wetlands, and to determine if restored wetlands are more susceptible to fish influences. To reach these objectives I am studying 20 wetlands equally partitioned among four groups of wetlands: natural without fish, natural with fish, restored without fish, and restored with fish. I am testing effects of fish (presence/absence), wetland history (restored/natural), and fish-history interactions on ecological characteristics of wetlands. Characteristics measured include abundance of aquatic invertebrates, amphibians, and submerged macrophytes, as well as water-column levels of chlorophyll a, turbidity, nitrogen, and phosphorus. Results indicate that fathead minnows have dramatic impacts on the biota and water quality of wetlands. Wetlands with fathead minnows have fewer aquatic insects, large cladocerans, ostracods, calanoid copepods, and larval and adult tiger salamanders, as well as higher levels of chlorophyll a, total phosphorus, and turbidity compared to fishless sites. In contrast, wetland history had much less of an influence, with no consistent differences observed between restored and natural wetlands, and no consistent fish-history interactions. These results indicate that fathead minnows affect the species assemblage and abiotic components of both restored and natural wetlands, and restored and natural wetlands respond similarly to fish influences. Finally, similarities of measured variables in restored and natural wetlands indicate that wetland restorations are biologically successful.

Investigation of Ammonia Removal by Nitrification in Biological Treatment Systems Relevant to Moorhead Minnesota, Andrew T. Bradshaw, Department of Civil Engineering, North Dakota State University, Fargo, ND 58105. [Advisor: Wei Lin, Department of Civil Engineering] M.S. expected May 2001. Currently, Environmental Engineer, Moorhead (Minnesota) Water Treatment Plant.

The project is focused on nitrification of ammonia to nitrate by bacteria in biological or secondary wastewater treatment process. A literature review has been conducted as well as necessary background research pertaining to the history of flow characteristics and state of ammonia removal at the Moorhead Minnesota Waste Water Treatment Plant. This WWTP has occasional problems with the levels of ammonia discharges to the Red River of the North. The sequencing batch reactors have been constructed and set up; including necessary pumps, tubing, monitoring equipment, and operating scheme. The City of Moorhead has contributed toward purchasing necessary reagents, and much of the lab analysis are being performed at the wastewater plant. Initial start-up of the experiment occurred in the late summer of 1998. Four SBRs are being operated at a 3, 6, 9, and 12 day mean cell residence time. The time required for stabilization is being monitored.

Effects of Wind Mixers on Wastewater Stabilization Lagoon Systems. Lee Beauvais,Department of Civil Engineering, North Dakota State University, Fargo, ND 58105. [Advisor: Wei Lin, Department of Civil Engineering] M.S. expected May 2001. Currently, Environmental Engineer, Moore Engineering, West Fargo, ND.

The City of West Fargo uses a system of lagoons to treat its wastewater before the effluent is ultimately discharged into the Sheyenne River. Because of springtime odor problems associated with anaerobic conditions that develop under winter ice, wind generated mixers have been installed in the smaller of two primary lagoons to prevent septic conditions from occurring during winter. In addition to being able to keep the lagoons from going septic during winter, these wind mixers may be beneficial in the removal of BOD, nutrients, and suspended solids throughout the year. The purpose of this research is to determine the potential for additional treatment resulting from the mixing caused by the wind mixers. The objectives of this thesis project include the determination of the potential to increase the loading rate into the primary lagoon and a quantification of the affect of wind mixers on the removal rates of BOD and ammonia within primary lagoons. The primary lagoon containing the wind mixers has been monitored beginning after the first spring discharge, through subsequent filling and treatment, and ending at the time of the next discharge. Following this discharge, the mixers will be pinned to prevent mixing, and the lagoon will be monitored for the next cycle. The concentration and variation within the lagoon of such parameters as the BOD5, suspended solids, dissolved oxygen, fecal coliforms, and ammonia are being monitored throughout the two treatment cycles. From this data and climatic data, comparison of the wastewater stabilization rates can be made in order to determine the extent of the effects, if any, the wind mixers have on overall wastewater stabilization within the lagoon.

Presentations

Zimmer, K.D., M.G. Butler, M.A. Hanson, and W.G. Duffy. 1999. Influences of fathead minnows on nitrogen and phosphorus cycling in a prairie wetland. North American Benthological Society Meeting, Duluth, MN.

Hanson, M.A., K.D. Zimmer, and M.G. Butler. 1999. Prairie wetland food webs: consequences of stabilized water levels. North American Benthological Society Meeting, Duluth, MN.

Publications

Zimmer, K.D., M.A. Hanson, and M.G. Butler. In press. Factors Influencing Invertebrate Communities in Prairie Wetlands: A Multivariate Approach, Canadian Journal of Fisheries and Aquatic Science.

Noraker, T., K.D. Zimmer, M.G. Butler, and M.A. Hanson. (in press), Dispersion And Distribution Of Marked Fathead Minnows (Pimephales promelas), in Prairie Wetlands. Journal of Freshwater Ecology, Vol. 14.

Butler, M.D., K.D. Zimmer, M.A. Hanson and W.G. Duffy, 1998, Influences of Fathead Minnows on Nutrient Partitioning, Water Clarity, and Ecosystem Structure in Prairie Wetlands, Rept. No. ND96-02, North Dakota Water Resources Research Institute, North Dakota State University, Fargo, North Dakota, 72 pages.

Jones, J.P., P.J. Gerla, and S.F. Korom. 1998. Stochastic Analysis of Three-dimensional, Heterogeneous Capture Zones, in Proceedings of MODFLOW '98, E. Poeter, C. Zheng, and M. Hill, eds., Colorado School of Mines, Golden CO, vol. 2, pp. 751-758.

Theses and Dissertations

Jones, Jon Paul, Determining Capture Zones for Three-Dimensional, Heterogeneous, Anisotropic Aquifers by Monte Carlo Analysis, Department of Geology and Geological Engineering, “M.S. Thesis,” Department of Geology and Geological Engineering, University of North Dakota, Grand Forks, ND.

Preliminary Results from a In-Situ Denitrification Test within the Elk Valley Aquifer., Department of Geological Engineering, Box 8358, University of North Dakota, Grand Forks, ND 58202-8358. [Advisor: Dr. Scott F. Korom, Department of Geology and Geological Engineering] M.S. December 1998. Currently, Research Associate and Manager of the UND Water Quality Laboratory, Department of Geology and Geological Engineering.

Nitrate concentrations in the Elk Valley Aquifer (EVA) in Northeast North Dakota tend to be greatest at the water table and decrease with depth. Denitrification is a likely explanation for this stratifi­cation with sulfide minerals and organic carbon in the shale of the aquifer sediments serving as electron donors.

Two stainless steel chambers were placed below the water table about 2 km west of Larimore, ND in the Elk Valley aquifer. The chambers were made from 1.5-m lengths of 40-cm diameter pipe. They formed in-situ microcosms (ISMs) to test the hypothesis that denitrification occurs in the sediments of the EVA. On October 30, 1997 about 87 L of water were removed from the research ISM and spiked with enough potassium nitrate and potassium bromide, which serves as a tracer for nitrate, to yield a nitrate-nitrogen (N) concentration of 140 mg/L and a bromide concentration of 83 mg/L. The water was then pumped back into the research ISM. This task was repeated for the control ISM except only potassium bromide was added to yield a bromide concentration of 675 mg/L. The ionic strengths of the chemicals added to both ISMs were about equal. Since installation, both ISMs have been sampled monthly. Preliminary results for the control ISM show bicarbonate, bromide, and sulfate concentrations have decreased to about 80% of their initial concentrations. Presumably the bromide has decreased because of dilution with native groundwater, which has low bromide concentrations. It is not evident why the bicarbonate and sulfate concentrations have decreased. Preliminary results for the research ISM show a decrease in bicarbonate, bromide, and nitrate-N. However, the nitrate-N has decreased at a faster rate than the bromide, which supports the hypothesis that denitrification is occurring in this ISM. Nitrate reduction was accompanied by an increase in sulfate concentration to 276% of its initial concentration. These results indicate that sulfides served as the electron donors for the observed denitrification. Furthermore, the background arsenic concentration in the research ISM was 11.0 ± 13.6 (±1 standard deviation) mg/L compared to 109 ±101 mg/L in the control ISM. This result may indicate that the oxidizing conditions caused by the addition of nitrate is oxidizing arsenic (III) to arsenic (V), which is typically less soluble in groundwater environments.

Estimating the Effect Wetlands Have on Flood Hydrographs Through Computer Simulation. Aaron J. Meyer, Department of Agricultural Economics, North Dakota State University, Fargo, ND 58105. [Advisor: Dr. Jay A. Leitch, Department of Agricultural Economics] M.S. May, 1998. Currently, Water Resource Protection and Program Management Specialist, Stearns County SWCD, Waite Park, MN.

The purpose of this study was to assess how effectively wetlands provide flood control. Synthetic watersheds, partially based on actual watersheds, were modeled to estimate the effect wetland location, initial water levels, storm intensities, and watershed shape have on flood hydrographs. Comparisons of the percentage changes in peak and total flows were made among simulated outlet hydrographs. Upland wetlands provided the greatest reductions in peak flows, while wetland location had no effect on total flows. Reductions in total flows were influenced by initial wetland water levels, but reductions in peak flows were not. Wetlands provided greater flood control for high frequency storms than for low frequency storms. Watershed shape primarily influenced lag times and had no effect on how wetlands influenced flood hydrographs. Understanding how wetlands affect flood hydrographs will help to formulate better flood prevention policies and management of wetlands.

Phytoplankton Community Structure Under Ice in Shallow North Dakota Lakes. Karen A. Phillips, Department of Botany-Biology, North Dakota State University, Fargo, ND 58105. [Advisor: Dr. Marvin Fawley, Department of Botany-Biology] Ph.D. May 1998. Currently, Post-Doctoral Research Associate, Department of Biology, NDSU.

Winter phytoplankton dynamics under ice in temperate lake systems are not well understood. The general model of freshwater phytoplankton seasonal distribution suggests that phyto­plankton survival is minimal under winter conditions. A review of the primary literature indicates that winter phytoplankton dynamics are oversimplified in the general model of seasonal distribution. The winter phytoplankton communities are often highly diverse and may produce a significant portion of the overall biomass in temperate systems. However, long-term studies of winter phytoplankton community structure have not been performed. For three consecutive winters (1994-1997), phytoplankton samples were collected under ice at four sites on three lakes in Arrowwood National Wildlife Refuge (ANWR), near Pingree, North Dakota. Three separate studies evolved from the ANWR collections: 1) phytoplankton community structure; 2) phytoplankton blooms associated with elevated oxygen levels; and 3) diversity of coccoid green algae. In the first study, 85 taxa were identified and enumerated. The winter phytoplankton community under the ice was dominated by winter annuals such as Synura uvella and Peridinium aciculiferum and eurythermal organisms such as cryptomonads, euglenoids and coccoid green algae. In the second study, a dramatic increase in oxygen concentration that was associated with a phytoplankton bloom during late February and early March of 1996 and 1997 was observed. In 1996, the bloom was composed of the dinoflagellate, Peridinium aciculiferum, and several species of cryptomonads. However, in 1997, a similar bloom of P. aciculiferum was followed by a bloom of several species of euglenoids. Finally in the third study, HPLC and PCR based methods were used to examine the diversity of autosporic coccoid green algae isolated from ANWR. Six 18S rDNA genotypes of coccoid trebouxiophytes, 3 genotypes of coccoid chlorophytes and 1 genotype of coccoid eustigmatophyte were detected in winter isolates from the Arrowwood refuge lakes. The overall results of these studies clearly indicate that a diverse phytoplankton community thrives despite the thick ice cover and very cold conditions.

Environmentally Friendly Determination of “Oil and Grease” in North Dakota Water Sources. Richard J. Jaeger, Department of Chemistry, University of North Dakota, Grand Forks, ND 58202. [Advisor: David T. Pierce, Department of Chemistry] Ph.D. expected 1999.

This research involves the production of an environmentally friendly method for the detection of various organic contaminants in water. The method involves a simple way of com­bining solid phase microextraction (SPME) with a quartz crystal microbalance (QCM) for determining various organic pollutants. The instrumentation includes the use of a commercially available QCM crystal coated with a poly(dimethylsiloxane) film that is placed in a flow-through cell in which contaminated solutions are passed over the crystal for analysis. The organic pollutants are selectively extracted from the aqueous phase into the polymer coating, based on solid phase microextraction theory. The QCM is a piezoelectric device capable of extremely sensitive mass measurements. The detector is a quartz crystal that oscillates in a mechanically resonant mode by application of an alternating, high- frequency voltage across electrodes deposited on both sides of the crystal. The electrodes overlap in the center of the crystal with tabs extending from each to the edge of the crystal where electrical contact is made. Alternating potential across the crystal causes vibrational motion of the quartz crystal that is influenced by the inertia of a mass deposited on the surface of the crystal face.

Results obtained to date indicate that poly(dimethylsiloxane) films can be placed onto QCM crystals with varied thickness, and are completely reusable after an extraction is performed. Interaction equilibrium times between the contaminants and the layered films are less than four minutes, which is an order of magnitude faster than similar techniques used to determine various organic pollutants in water. Preliminary experiments to develop the sensor concentrated on individual organic pollutants instead of aggregate “oil and grease” samples. The research project has determined precise interactions between the film and aromatic BTEX compounds (benzene, toluene, ethylbenzene, xylene) and various aliphatic compounds (hexane, heptane, octane) commonly found in real water samples. This method allows each compound to have a distinct preference towards the film with detection limits near 200 ppb.

Presentations

A Device for Measuring Denitrification in the Unconsolidated Shaly Deposits of the Elk Valley Aquifer. A.J. Schlag and S.F. Korom, Geology and Geological Engineering, University of North Dakota, Grand Forks, ND. Joint EPSCoR North Dakota/South Dakota State Conference, September 26-27, 1997,

Phillips, Karen and Marvin Fawley, 1998, Winter phytoplankton blooms associated with elevated oxygen levels under ice in shallow North Dakota lakes, ASLO/ESA joint meeting, St. Louis, MO.

Phillips, Karen and Marvin Fawley, 1998, Diversity of coccoid algae isolated from the Arrowwood National Wildlife Refuge lakes, North Dakota, during winter, Phycological Society of America Annual Meeting, Flagstaff, AZ.

Publications

Marvin W. Fawley, Survey of the Phytoplankton Communities Involved in Oxygen Supersaturation Under the Ice in Shallow North Dakota Lakes, Technical Completion Report No. ND94-05, North Dakota Water Resources Research Institute, October, 1997, 6 pp.

Theses and Dissertations

Meyer, Aaron J. 1998. Estimating the Effect Wetlands Have on Flood Hydrographs Through Computer Simulation. M.S. Thesis, North Dakota State University, Fargo, May, 1998.

Phillips, Karen A., Phytoplankton community structure under ice in shallow North Dakota lakes, Ph.D. Dissertation, North Dakota State University, Fargo, ND, 104 pp., May 1998.