Browsing by Subject "Wetland"
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Item Biogeochemical Interactions and Cycling of Sulfur, Iron, and Carbon in Sulfate-Impacted Riparian Wetlands and Wild Rice Waters(2018-08) Torgeson, JoshuaSulfide accumulation in the porewater of freshwater aquatic systems has been shown to inhibit the growth of many aquatic macrophytes, including wild rice. While interactions between sulfur (S), carbon (C), and iron (Fe) cycles are recognized, secondary “cryptic” S cycles are much less understood; these cycles favor reduction of sulfate over Fe, contrary to traditional thermodynamic expectations; these “cryptic” cycles have been suggested to occur at Second Creek through models by Ng et al. (2017). Using field observations, hydrologic monitoring, and geochemical analyses, we found that changes in hyporheic flux result in changes in porewater SO42- concentrations. Additionally, we have found that intermediate valence S species may act as primary sinks for excess dissolved sulfide. Our comparison study between a SO42--impacted stream and a less-impacted river demonstrates that the accumulation of porewater sulfide may be suppressed through limited TOC, excess sediment Fe, or through generation of S-intermediates.Item Constructed wetland used to treat nitrate pollution generated from agricultural tile drainage waters in Southern Minnesota(2014-09) Ross, Nikol BaileyNitrate molecules are highly soluble in water and are bioavailable to plants. These properties are why excess nitrates in water are one of the main causes of hypoxia in the northern Gulf of Mexico. Over 90% of these nitrates originate from non-point sources such as agricultural fields. In fields with tile drainage systems nitrates have a swift passageway from field to surface waters. This study focuses on one Midwestern farm field located in southern Minnesota, along Elm Creek, a Blue Earth tributary. Tile drainage water from this field discharges into Elm Creek at a concentration averaging 23.0 mg/L NO3 as NO3-N. During the spring of 2013 a three celled treatment wetland was constructed adjacent to Elm Creek. The tile drainage system was re-routed to discharge into the constructed wetland. In the 2013 field season water volumes were monitored continuously and water samples were taken from the inlet, the wetland cells, and the outlet on a periodic basis. During the season the volume of tile drainage water that reached Elm Creek as surface water was reduced by 82%. The concentration of NO3-N in the water was not significantly reduced. However, the total load of NO3-N that reached Elm Creek as surface water was reduced by 262 to 332 pounds (14.4-18.2 lbs./acre). Most of the water that did not reach Elm Creek infiltrated into the subsurface soils and still contained NO3-N. Using the MPCA's (2013) estimates of groundwater denitrification for agroecoregions, a 45% reduction rate was applied at this location. When the 45% reduction rate is applied to the subsurface load it is estimated that 113.0 to 134 lbs. (6.21-7.36 lbs./acre) of NO3-N were removed from the infiltrated water. Thus a total of 124 to 172 lbs. (6.81-9.45 lbs./acre) of NO3-N were removed from the entire wetland system which accounts for 37.1-43.3% of the NO3-N.A concurrent laboratory experiment was set up in 2013 to test the effectiveness of different soils and vegetation at removing nitrate loads. Wetland mesocosm experiments were set up with soil collected from the field site and the design vegetation used in the field cells. Three vegetated mesocosm tanks were planted in Coland soils with Switchgrass (Panicum virgatum), Fringed Sedge (Carex crinita) and a tank with an equal mix of Dark Green Bulrush (Scirpus atrovirens), Panicum virgatum, and Carex crinita. The results showed that the mixed vegetation regime and the Panicum virgatum had significantly greater nitrate removal than the control (Coland bare soil). The mixed vegetation mesocosm had the highest amount of nitrate removal after 10 days at 34.9%. There was no significant difference in the nitrate removal rates in the soils tested.Item Establishment of Native Sedge Vegetation in Created Wetlands(Minnesota Department of Transportation, 1999-02) Budelsky, Rachel A.; Cushing, Edward J.; Galatowitsch, Susan M.This report presents the results of a four-year study on techniques for revegetation of native sedges in created basins. Although often the dominant genus in shallow wetlands, sedges (Carex spp.) do not readily recolonize after restoration or creation of the water table. It is unlikely that sedges will naturally establish in created wetlands. The results of seed germination studies on five Carex species suggest the highest germination rates in fresh seeds - with one exception. Wet/cold storage also can prolong seed viability for at least two-and-a-half years. Dry storage is not recommended for wetland sedge seeds. Short-term wet/cold treatment after prolonged dry storage does not improve germination rates. Sensitive to deep water, rising water levels, and competition during the establishment year, seedlings grew well across a wide range of water depths in subsequent growing seasons. Both species outcompeted annual weeds within two to three growing seasons, but not Phalaris arundinacea (reed canary grass). The study recommends weed control during the establishment year to prevent the invasion of P. arundinacea. Wetland soil promotes seedling growth relative to other soils, but does not affect germination rates. Because of the potential for the introduction of undesirable weeds, the study does not recommend the use of donor wetland soil. Instead, study results suggest the potential for the use of organic top-dressings.Item Field Guide for Maintaining Rural Roadside Ditches(2014) Brady, Valerie; Axler, Richard P.; Schomberg, JesseItem Human Impacts to Minnesota Wetlands(University of Minnesota Duluth, 1991) Johnston, Carol AMinnesota’s 3.6 million ha of wetlands have been impacted by a variety of human activities, including agricultural drainage, urbanization, water control, and nonpoint source pollution. More than half of Minnesota's wetlands have been destroyed since the first European settlers arrived, an average loss of about 35,600 ha/yr. Drainage for agriculture is the major cause of wetland loss in Minnesota, particularly in southern Minnesota and the Red River Valley. In addition to impacting wetlands directly, wetland drainage affects downstream areas by increasing flood flows, and releasing sediment and nutrients. Urban development and highway construction affect a smaller proportion of Minnesota’s wetlands, but substantially alter their physical, chemical, and biological properties. Hydrology has a major influence on the structure and function of wetlands, so changes in the frequency, duration, depth, and timing o f wetland flooding can severely impact wetlands. While wetlands can assimilate low levels o f sediment and nutrient enrichment, excessive inputs can be detrimental. Peat harvesting is not currently extensive in Minnesota, but could cause substantial impacts. Cumulative impact, the incremental impact o f an action when added to other past, present, and reasonably foreseeable future actions, is becoming an area of increasing concern.Item Impact of large-scale irrigation on a closed basin wetland: Water flow alterations and participatory irrigation management effects on the Sultan Marshes ecosystem in Turkey(2008-07) Celik, Filiz DadaserThis dissertation analyzes alterations in a closed-basin wetland system resulting from the construction of a large-scale irrigation project in its catchment. The study was conducted at the Sultan Marshes ecosystem (Develi Basin, Turkey), which has been severely degraded within the last 20 years due to diversion of its major water sources for agricultural irrigation. Spatial changes in the Sultan Marshes from 1980 to 2003 were analyzed using satellite remote sensing. Changes in the areal coverages of lakes, marshes, agricultural, and steppe areas determined by unsupervised classification of four Landsat images showed that both lakes and marshes became smaller after construction of the irrigation project. Steppe areas expanded onto wetlands. Significant portion of northern (Kepir) marshes were converted to agriculture. Hydrologic changes in the Sultan Marshes were analyzed statistically and used to develop a dynamic hydrologic model of the system. Water levels dropped more than one meter in the lakes and marshes from 1993 to 2003, and decreases were observed in ground-water levels and spring flows, although precipitation and evaporation rates remained mostly stable. Simulations with the hydrologic model showed that even if surface water continues to be used for irrigation, reductions in appropriations from ground water and springs would restore and protect water levels in the marshes. Agricultural and environmental changes in the Develi Basin were analyzed after the irrigation management was transferred from state to "irrigation associations" in 1994. The analyses showed that irrigated areas and water use in the Develi Basin showed significant fluctuations. The area allocated to production of high water-consuming plants increased. Water fee collection rates were lower than 100%. Although soil and water quality in the Develi Basin did not change significantly, ground-water levels, flow rates from springs and water levels in the Sultan Marshes all dropped. Four recommendations were developed that would help to resolve the conflict between agricultural and wetland water requirements: (1) a basin-wide approach water planning, (2) more realistic water pricing, (3) demand-based irrigation scheduling, and (4) rehabilitation of the irrigation system. Economic costs and benefits associated with water diversions from agriculture to the wetlands were estimated, and the optimum or economically-efficient amount of water diversion was determined. When only direct-use values of the wetland (reed cutting, animal grazing and ecotourism) were included, the annual optimum amount of water diversion to the wetlands was found to be 5.2 million m 3 yr -1 (165 L s -1 ) compared to about 62 million m 3 yr -1 (1,957 L s -1 ) used in irrigation. Diversion of 5.2 million m 3 yr -1 water would be sufficient to restore the conditions in the marshes. The analysis showed that economically-efficient restoration of water levels in the Sultan Marshes is feasible with moderate amounts of water diversion.Item Influences of riparian buffers and soil variability on the hydrology of seasonal wetlands in Northern Minnesota(2012-12) Tersteeg, Daniel PatrickThe objectives of this research were to determine what effect buffering seasonal ponds following harvest of adjacent upland forest has on pond hydrology; as well as to investigate soil morphology associated with these ponds. Study areas were established in north central Minnesota in 2000 and buffer treatments assigned randomly to ponds included: control, uncut buffer, partial buffer, and clearcut buffer. One year of pre-harvest and five years of post-harvest data was collected to examine hydrologic characteristics and distinguish any differences between buffer treatments. Soil texture and hydraulic conductivity was analyzed to determine the influence on formation of seasonal ponds on the landscape. The results suggest that it is possible to manipulate hydrologic characteristics in seasonal ponds following upland harvest based on the type of buffer treatment. The presence of both Bt horizon formation and lithologic discontinuity suggests seasonal pond formation can be attributed to both geogenic and pedogenic processes.Item Literature Pertaining to the Environmental Impacts of Turfgrass Management on Wetlands(University of Minnesota Duluth, 1990) Johnston, Carol AThis report lists references pertaining to the environmental impact of turfgrass management, in the following categories: General Wetland References, Impacts of Wetland Loss, Construction Impacts to Wetlands, Impacts of Pesticides on Wetlands, Nonpoint Source Pollution from Urbanization, Impacts of Recreation, Cumulative Impacts to WetlandsItem Photochemical Production of Reactive Intermediates in Inland Surface Waters(2017-09) McCabe, AndrewReactive intermediates form when dissolved natural organic matter (DOM) absorbs sunlight in surface waters. These reactive intermediates include triplet excited states of dissolved organic matter (T*), reactive oxygen species, carbonate radical, and halide radicals. They are associated with a variety of physicochemical processes, including carbon and metal cycling, pathogen inactivation, and reactions with trace organic contaminants. T* is particularly important in these processes because it can react either through electron or energy transfer mechanisms and it is responsible for the formation of secondary reactive intermediates, such as singlet oxygen and radicals. The quantity and composition of DOM are key variables that control the rate and efficiency of T* formation, defined as the ratio of the rate of T* formation to the total rate of light absorption. As DOM is transported through aquatic environments, its composition is altered by natural and anthropogenically-influenced biogeochemical processes. Here, DOM composition is related to the reactivity of T* in stormwater and in temperate wetlands, two important aquatic systems involved in the production and transport of DOM. The rate and efficiency of T* formation were measured with two chemical probes, 2,4,6-trimethylphenol and trans,trans-2,4-hexadienoic acid, that quantify rates of T* electron transfer and energy transfer, respectively. DOM composition was characterized using absorption spectrophotometry, fluorescence spectroscopy, and Fourier transform ion cyclotron mass spectrometry. Within our sample set, the observed range in the efficiency of T* formation is <1%–14%, and shows a distinct dependence on watershed vegetative land cover and open water extent. The rate of T* formation increases with the concentration of dissolved organic carbon (DOC) while the efficiency of T* formation is independent of DOC. The data reported here suggests that DOM derived from vascular plants has a dual role, controlling both the rate of light absorption and the efficiency of T* formation.