A5009457955- Marine and coastal ecosystems
- Isotope Analysis in Ecology
- Microplastics and Plastic Pollution
- Recycling and Waste Management Techniques
- Marine Biology and Ecology Research
- Water Quality Monitoring and Analysis
- Geology and Paleoclimatology Research
- Fish Ecology and Management Studies
- School Choice and Performance
- Mass Spectrometry Techniques and Applications
- Hydrocarbon exploration and reservoir analysis
- Mercury impact and mitigation studies
- Teacher Education and Leadership Studies
- Groundwater and Isotope Geochemistry
- Methane Hydrates and Related Phenomena
- Soil and Water Nutrient Dynamics
- Hydrology and Watershed Management Studies
- Water Quality and Pollution Assessment
- International Relations and Foreign Policy
- Ocean Acidification Effects and Responses
- Atmospheric and Environmental Gas Dynamics
- Analytical chemistry methods development
- Atmospheric chemistry and aerosols
- Nuclear Issues and Defense
- Aquatic Ecosystems and Phytoplankton Dynamics
University of Minnesota, Duluth
2015-2024
University of Minnesota
2009-2023
Minnesota Department of Natural Resources
2023
Article 19
2016-2021
Duluth Clinic
2014-2019
National Louis University
2014-2019
University of Iowa
2015
Michigan State University
2014
Oxford Research Group
2013
Old Dominion University
2002-2010
A new approach for parameterizing dissolved organic matter (DOM) ultraviolet‐visible absorption spectra is presented. Two distinct spectral slope regions (275‐295 nm and 350‐400 nm) within log‐transformed were used to compare DOM from contrasting water types, ranging wetlands (Great Dismal Swamp Suwannee River) photobleached oceanic (Atlantic Ocean). On the basis of size‐fractionation studies (ultrafiltration gel filtration chromatography), 275‐295‐nm region ratio these slopes ( S R ; :...
While plastic pollution in marine and freshwater systems is an active area of research, there not yet in-depth understanding the distributions, chemical compositions, fates plastics aquatic environments. In this study, magnitude, distribution, common polymers microplastic surface waters western Lake Superior are determined. Analytical methodology, including estimates ambient contamination during sample collection processing, described employed. Microscopy, pyrolysis-gas chromatography/mass...
Flooding is a major disturbance that impacts aquatic ecosystems and the ecosystem services they provide. Predicted increases in global flood risk due to land use change water cycle intensification will likely only increase frequency severity of these impacts. Extreme flooding events can cause loss life significant destruction property infrastructure, effects are easily recognized frequently reported media. However, also has many other on people through freshwater services, which often go...
Applying two-dimensional correlation spectroscopy to 13C NMR and FTIR spectra of the high molecular-weight dissolved organic matter (HMW-DOM) isolated along an Elizabeth River/Chesapeake Bay salinity transect shows that HMW-DOM consists three major components have different biogeochemical reactivities. The first appears be a heteropolysaccharide (HPS) component its contribution carbon increases as we approach marine offshore. second composed carboxyl-rich compounds (CRC); percentage...
We present a lake‐wide investigation of Lake Superior carbon and organic matter biogeochemistry using radiocarbon, stable isotope, concentrations. Dissolved inorganic (DIC) abundance in the lake was 121–122 Tg C, with offshore concentration δ 13 C values being laterally homogenous tightly coupled to physical thermal regime biochemical processes. Offshore Δ 14 DIC (50–65‰) exhibited lateral homogeneity more enriched than co‐occurring atmospheric CO 2 (∼38‰); nearshore (36–38‰) similar . (DOC)...
This study applies radiocarbon and stable carbon isotopic distributions to investigate sources cycling within Lake Superior. We report the (Δ 14 C) isotope ( δ 13 values concentrations dissolved organic (DOC), particulate (POC), inorganic (DIC) in lake's western basin water column. Samples were taken during spring mixing late‐summer thermal stratification over a 2‐yr period (2007–2009). Distinct processes operating surface (photosynthesis) deep waters (sediment resuspension pore‐water...
Identifying the sources and fate of microplastics in natural systems has garnered a great deal attention because their implications for ecosystem health. This work characterizes size fraction, morphology, color, polymer composition western Lake Superior its adjacent harbor sampled August September 2021. The results reveal that overall microplastic counts are similar, with stations ranging from 0.62 to 3.32 per liter lake ranged 0.83 1.4 liter. However, meaningful differences between sample...
An amplified enzyme-linked immunosorbent assay (amp-ELISA) was compared with the AOAC Official Method 977.26 for detection of Clostridium botulinum and its toxins in foods. Eleven laboratories participated results 10 were used study. Two anaerobic culture media, tryptone peptone glucose yeast extract (TPGY) cooked meat medium (CMM) to generate toxic samples types A, B, E, F botulinal strains. Nonbotulinal clostridia also tested. The toxicity each determined by method, cultures then diluted,...
We performed laboratory studies to determine the effects of salinity on photodegradation dissolved organic matter (DOM) from Great Dismal Swamp, Virginia, an important source terrestrial DOM lower Chesapeake Bay. Samples were created by mixing Swamp water (ionic strength ~ 0 mol L-1) with modified artificial seawater solutions differing salinities while keeping final carbon (DOC) concentration constant. These samples then irradiated for 24 h in a light box providing ultraviolet (UV) similar...