Nitrate Reduction Approaches

Resource /Energy Economics and Policy, Q25,

Micro-level econometric and water-quality modeling: simulation of nutrient management policy effects

Large surface areas of lakes and streams are impaired by nutrient contributions from agricultural nonpoint sources. This research develops a fully integrated economic and water quality model of an actual watershed to assess alternative nutrient abatement polities in terms of their economic efficiency and water quality effects. The policies examined include fertilizer taxes, application rate caps, uniform reductions, and a cap-and-trade fertilizer application right trading scheme. A micro-econometric field scale model of nutrient application is estimated using USDA Agricultural Resource Management Survey (ARMS) data combined with prices and spatially detailed soil data. Estimation results are interfaced with the Soil and Water Assessment Tool (SWAT) to determine the changes in water quality that would result from each scenario. Results suggest that, given a fixed expenditure, the differences in water quality effects across policies are small. However, a uniformly-applied application cap can provide the largest improvement due to the spatial distribution of application patterns. Additionally, there is a great deal of variability in results at the sub-watershed level as compared to the watershed outlet

Cropland Cash Rental Rates in the Upper Mississippi River Basin

The report documents the creation of estimates for cropland cash rental rates in the Upper Mississippi River Basin in 1997. Although the basic data come from disparate sources, we employ a unifying estimation procedure based on the presumption that the cropland cash rental rate is an increasing function of corn yield potential. The rates are estimated at some 42,000 National Resources Inventory data points representing cropland in Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, South Dakota, and Wisconsin

Indications and Relative Utility of Lower Endoscopy in the Management of Clostridium difficile Infection

Background. Diagnosis and management of Clostridium difficile infection (CDI) rely upon clinical assessments and diagnostic studies. Among diagnostic tests, lower gastrointestinal (GI) endoscopy in the setting of CDI remains controversial. Objective. To describe the role of lower endoscopy in CDI management. Methods. Retrospective study of lower endoscopies in CDI at four metropolitan hospitals, July 2005 through December 2007. Results. Of 1760 CDI inpatients, 45 lower endoscopies were performed on 43 patients. Most common indications were ruling out other etiologies (42%), inconclusive stool studies (36%), and worsening course (11%). Most endoscopies (73%) had positive findings, including pseudomembranous colitis (49%) and nonspecific colitis (24%). Biopsies were performed in 31 cases, more with nonspecific colitis (10/11, 92%) compared to pseudomembranous colitis (14/22, 64%). Conclusion. While not recommended as a primary screening tool, lower GI endoscopy can add valuable information in CDI when other colonic pathologies may exist, studies are inconclusive, or clinical status worsens

Estimating Physical Activity and Sleep using the Combination of Movement and Heart Rate: A Systematic Review and Meta-Analysis

International Journal of Exercise Science 16(7): 1514-1539, 2023. The purpose of this meta-analysis was to quantify the difference in physical activity and sleep estimates assessed via 1) movement, 2) heart rate (HR), or 3) the combination of movement and HR (MOVE+HR) compared to criterion indicators of the outcomes. Searches in four electronic databases were executed September 21-24 of 2021. Weighted mean was calculated from standardized group-level estimates of mean percent error (MPE) and mean absolute percent error (MAPE) of the proxy signal compared to the criterion measurement method for physical activity, HR, or sleep. Standardized mean difference (SMD) effect sizes between the proxy and criterion estimates were calculated for each study across all outcomes, and meta-regression analyses were conducted. Two-One-Sided-Tests method were conducted to meta-analytically evaluate the equivalence of the proxy and criterion. Thirty-nine studies (physical activity k = 29 and sleep k = 10) were identified for data extraction. Sample size weighted means for MPE were -38.0%, 7.8%, -1.4%, and -0.6% for physical activity movement only, HR only, MOVE+HR, and sleep MOVE+HR, respectively. Sample size weighted means for MAPE were 41.4%, 32.6%, 13.3%, and 10.8% for physical activity movement only, HR only, MOVE+HR, and sleep MOVE+HR, respectively. Few estimates were statistically equivalent at a SMD of 0.8. Estimates of physical activity from MOVE+HR were not statistically significantly different from estimates based on movement or HR only. For sleep, included studies based their estimates solely on the combination of MOVE+HR, so it was impossible to determine if the combination produced significantly different estimates than either method alone

Possible Missing Sources of Atmospheric Glyoxal Part II: Oxidation of Toluene Derived from the Primary Production of Marine Microorganisms.

BACKGROUND: Glyoxal has been implicated as a significant contributor to the formation of secondary organic aerosols, which play a key role in our ability to estimate the impact of aerosols on climate. Elevated concentrations of glyoxal over open ocean waters suggest that there exists an additional source, different from urban and forest environments, which has yet to be identified. METHODS: Based on mass spectrometric analyses of nascent sea spray aerosols (SSAs) and gas-phase molecules generated during the course of a controlled algal bloom, the work herein suggests that marine microorganisms are capable of excreting toluene in response to environmental stimuli. Additional culture flask experiments demonstrated that pathogenic attack could also serve as a trigger for toluene formation. Using solid-phase microextraction methods, the comparison of samples collected up-channel and over the breaking wave suggests it was transferred across the air-water interface primarily through SSA formation. RESULTS: The presence and then absence of phenylacetic acid in the SSA days prior to the appearance of toluene support previous reports that proposed toluene is produced as a metabolite of phenylalanine through the Shikimate pathway. As a result, once in the atmosphere, toluene is susceptible to oxidation and subsequent degradation into glyoxal. CONCLUSIONS: This work adds to a minimal collection of literature that addresses the primary production of aromatic hydrocarbons from marine microorganisms and provides a potential missing source of glyoxal that should be considered when accounting for its origins in remote ocean regions

Taxon-Specific Aerosolization of Bacteria and Viruses In an Experimental Ocean-Atmosphere Mesocosm

Ocean-derived, airborne microbes play important roles in Earth’s climate system and human health, yet little is known about factors controlling their transfer from the ocean to the atmosphere. Here, we study microbiomes of isolated sea spray aerosol (SSA) collected in a unique ocean–atmosphere facility and demonstrate taxon-specific aerosolization of bacteria and viruses. These trends are conserved within taxonomic orders and classes, and temporal variation in aerosolization is similarly shared by related taxa. We observe enhanced transfer into SSA of Actinobacteria, certain Gammaproteobacteria, and lipid-enveloped viruses; conversely, Flavobacteriia, some Alphaproteobacteria, and Caudovirales are generally under-represented in SSA. Viruses do not transfer to SSA as efficiently as bacteria. The enrichment of mycolic acid-coated Corynebacteriales and lipid-enveloped viruses (inferred from genomic comparisons) suggests that hydrophobic properties increase transport to the sea surface and SSA. Our results identify taxa relevant to atmospheric processes and a framework to further elucidate aerosolization mechanisms influencing microbial and viral transport pathways