Browsing by Author "Chun, Chan Lan"

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    Environmental Impacts of Potassium Acetate as a Road Salt Alternative (University of Minnesota evaluation)
    (Minnesota Department of Transportation, 2022-07) Gulliver, John S.; Chun, Chan Lan; Weiss, Peter T.; Erickson, Andrew J.; Herb, William; Henneck, Jerry; Cassidy, Kathryn
    Road salt (NaCl) is used predominantly across the state for winter road anti-icing (as brine) and de-icing (as a solid) operations. Road salt is used because it is inexpensive and effective, but the thousands of tons used annually have resulted in increasing chloride concentrations of surface water bodies throughout Minnesota. In many cases, chloride concentrations are above regulatory limits, which results in the loss of aquatic biota and the water body being labeled as impaired. Thus, there is a need for one or more road salt alternatives (RSAs) that are effective, relatively inexpensive, and environmentally friendly. This report investigates the environmental impacts of potassium acetate (Kac), which is effective at lower temperatures than most other potential RSAs and is also less corrosive to steel than conventional road salt. Field measurements indicate that current applications of KAc do not have a substantial influence on biochemical oxygen demand (BOD) and microbiological water quality in Lake Superior. However, KAc concentrations due to application to 25% of the roads in the Miller Creek watershed are predicted to be above the toxic limit for water fleas. We believe that KAc could be used in the most precarious winter driving safety locations, but not over all watershed roads or for all storms. Acetate could be used as a general organic anti-icer, but in combination with another cation, such as sodium or magnesium.
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    Mobile Water Treatment Demonstration System for Sulfate Reduction
    (University of Minnesota Duluth, 2022-08) Cai, Meijun; Rao, Shashi; Post, Sara P; Hanson, Adrian; Chun, Chan Lan; Johnson, Lucinda B; Hudak, George J; Weberg, Rolf
    The State of Minnesota adopted a sulfate standard of 10 mg/L for wild rice waters in 1973. Although under review, current technology for achieving this standard is a challenge for small industries and municipalities. Membrane-based technologies such as nanofiltration and reverse osmosis are capable of treating water to reach the Minnesota wild rice water sulfate standard; however, they typically require high capital and operation costs. Therefore, there is a need to develop cost-effective sulfate treatment alternatives. The Natural Resources Research Institute (NRRI) has developed a treatment system based on barite chemical precipitation reactions to reduce sulfate levels in water from 60-200 mg/L to below 10 mg/L. This system was demonstrated at bench-scale batch and continuous tests. The data collected from these lab tests were used to scale up the process to a trailer-based modular demonstration treatment system. This study highlights the outcomes of field pilot tests conducted by NRRI using this treatment system. The objectives of the field pilot trials were to: (1) Evaluate the efficacy of the chemical precipitation process when scaled up from 200 ml/min to 2 GPM; (2) Study the effect of co-existing chelating organics of the raw wastewater on barite precipitation reactions; (3) Optimize the chemical reagent dosage levels; (4) Investigate the potential of reusing process sludge to promote precipitation reactions; (5) Identify strategies to minimize scale formation on process equipment; and (6) Estimate the chemical reagent costs. The pilot tests were conducted using effluent from two municipal wastewater treatment plants (WWTP)—the Virginia WWTP and the Grand Rapids WWTP in northeastern Minnesota—from June 2021 until October 2021.
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    Seasonal influence on detection probabilities for multiple aquatic invasive species using environmental DNA
    (2023-12-14) Rounds, Christopher; Arnold, Todd W; Chun, Chan Lan; Dumke, Josh; Totsch, Anna; Keppers, Adelle; Edbald, Katarina; García, Samantha M; Larson, Eric R; Nelson, Jenna KR; Hansen, Gretchen JA; round060@umn.edu; Rounds, Christopher; University of Minnesota Fisheries Systems Ecology Lab
    Aquatic invasive species (AIS) are a threat to freshwater ecosystems. Documenting AIS prevalence is critical to effective management and early detection. However, conventional monitoring for AIS is time and resource intensive and is rarely applied at the resolution and scale required for effective management. Monitoring using environmental DNA (eDNA) of AIS has the potential to enable surveillance at a fraction of the cost of conventional methods, but key questions remain related to how eDNA detection probability varies among environments, seasons, and multiple species with different life histories. To quantify spatiotemporal variation in the detection probability of AIS using eDNA sampling, we surveyed 20 lakes with known populations of four aquatic invasive species: Common Carp (Cyprinus carpio), Rusty Crayfish (Faxonius rusticus), Spiny Waterflea (Bythotrephes longimanus), and Zebra Mussels (Dreissena polymorpha). We collected water samples at 10 locations per lake, five times throughout the open water season. Quantitative PCR was used with species-specific assays to determine the presence of species DNA in water samples. Using Bayesian occupancy models, we quantified the effects of lake and site characteristics and sampling season on eDNA detection probability. These results provide critical information for decision makers interested in using eDNA as a multispecies monitoring tool and highlight the importance of sampling when species are in DNA releasing life history stages.