A5038898780- Marine and coastal ecosystems
- Climate change and permafrost
- Cryospheric studies and observations
- Atmospheric and Environmental Gas Dynamics
- Microbial Community Ecology and Physiology
- Geology and Paleoclimatology Research
- Isotope Analysis in Ecology
- Arctic and Antarctic ice dynamics
- Methane Hydrates and Related Phenomena
- Soil and Water Nutrient Dynamics
- Polar Research and Ecology
- Water Quality Monitoring and Analysis
- Fish Ecology and Management Studies
- Marine Biology and Ecology Research
- Water Quality and Pollution Assessment
- Atmospheric chemistry and aerosols
- Groundwater and Isotope Geochemistry
- Peatlands and Wetlands Ecology
- Aquatic Ecosystems and Phytoplankton Dynamics
- Hydrology and Watershed Management Studies
- Mercury impact and mitigation studies
- Geological Studies and Exploration
- Coastal wetland ecosystem dynamics
- Diverse Musicological Studies
- Ocean Acidification Effects and Responses
National High Magnetic Field Laboratory
2016-2025
Florida State University
2016-2025
University of California, Davis
2006-2023
University of Alaska Southeast
2021-2023
School of the Art Institute of Chicago
2023
University of Tennessee at Knoxville
2023
Tall Timbers Research Station and Land Conservancy
2022
Woodwell Climate Research Center
2010-2022
Medtronic (United States)
2022
Sainsbury Laboratory
2022
The fluorescent properties of dissolved organic matter (DOM) are often studied in order to infer DOM characteristics aquatic environments, including source, quantity, composition, and behavior. While a potentially powerful technique, single widely implemented standard method for correcting presenting fluorescence measurements is lacking, leading difficulties when comparing data collected by different research groups. This paper reports on large-scale interlaboratory comparison which natural...
Congo River water was filtered and then irradiated for 57 d in a solar simulator, resulting extensive photodegradation of dissolved organic matter (DOM). Whole‐water (i.e., unfractionated) DOM analyzed pre‐ post‐irradiation using ultrahigh resolution Fourier transform ion cyclotron mass spectrometry (FT‐ICR MS), revealing the following three pools classified based upon their photoreactivity: (1) photo‐resistant, (2) photo‐labile, (3) photo‐produced. Photo‐resistant heterogeneous, with most...
Abstract Globally, inland waters receive a significant but ill‐defined quantity of terrestrial carbon (C). When summed, the contemporary estimates for three possible fates C in (storage, outgassing, and export) highlight that landscapes may deliver upward 5.1 Pg annually. This review flux over last decade has revealed an average increase ∼ 0.3 yr −1 , indicating historical underestimation amount terrestrial‐C exported to waters. The continual also underscores large data gaps uncertainty. As...
Global biomass burning generates 40 million to 250 tons of charcoal every year, part which is preserved for millennia in soils and sediments. We have quantified dissolution products a wide range rivers worldwide show that globally, major portion the annual production lost from via subsequent transport ocean. The global flux soluble accounts 26.5 ± 1.8 per ~10% riverine dissolved organic carbon (DOC). suggest mobilization DOC out mechanistically coupled. This study closes gap budget provides...
Dissolved organic carbon (DOC) concentration and chromophoric dissolved matter (CDOM) parameters were measured over a range of discharge in 30 U.S. rivers, covering diverse assortment fluvial ecosystems terms watershed size landscape drained. Relationships between CDOM absorption at wavelengths ( 254 , 350 440 ) DOC the watersheds found to correlate strongly positively for majority rivers. However, four rivers (Colorado, Colombia, Rio Grande St. Lawrence) exhibited statistically weak...
Photochemical degradation of Congo River dissolved organic matter (DOM) was investigated to examine the fate terrigenous DOM derived from tropical ecosystems. Tropical riverine receives greater exposure solar radiation, particularly in large river plumes discharging directly into open ocean. Initial exhibited carbon (DOC) concentration and compositional characteristics typical rich blackwater systems. During a 57 day irradiation experiment, shown be highly photoreactive with decrease DOC,...
High‐latitude northern rivers export globally significant quantities of dissolved organic carbon (DOC) to the Arctic Ocean. Climate change, and its associated impacts on hydrology potential mobilization ancient matter from permafrost, is likely modify flux, composition, thus biogeochemical cycling fate exported DOC in Arctic. This study examined concentration composition (DOM) across hydrograph Siberia's Kolyma River, with a particular focus spring freshet period when majority annual load...
Abstract Climate change induced permafrost thaw in the Arctic is mobilizing ancient dissolved organic carbon (DOC) into headwater streams; however, DOC exported from mouth of major arctic rivers appears predominantly modern. Here we highlight that (>20,000 years B.P.) rapidly utilized by microbes (~50% loss <7 days) and decay rates (0.12 to 0.19 day −1 ) exceed those for a river (Kolyma: 0.09 ). Permafrost exhibited unique molecular signatures, including high levels aliphatics were...
The seasonal and spatial variability of dissolved organic matter (DOM) quantity chemical composition were investigated in the Yukon River basin Alaska, United States, northwestern Canada. Dissolved carbon (DOC), chromophoric DOM (CDOM), lignin phenols measured across a range source waters hydrograph. Strong relationships determined between CDOM both DOC phenols, highlighting potential for deriving detailed temporal distributions from monitoring. Maximum concentrations parameters observed...
Abstract Ongoing climate warming in the Arctic will thaw permafrost and remobilize substantial terrestrial organic carbon (OC) pools. Around a quarter of northern OC resides Siberian Yedoma deposits, oldest form carbon. However, our understanding degradation fate this ancient coastal fluvial environments still remains rudimentary. Here, we show that dissolved (DOC, >21,000 14 C years), DOC ever reported, is mobilized stream waters draining outcrops. Furthermore, highly biolabile: 34 ±...
The link between composition and reactivity of dissolved organic matter (DOM) is central to understanding the role aquatic systems play in global carbon cycle; yet, unifying concepts driving molecular have yet be established. We characterized 37 DOM isolates from diverse ecosystems, including their stable radiocarbon isotopes (δ13C-dissolved (DOC) Δ14C-DOC), optical properties (absorbance fluorescence), (ultrahigh resolution mass spectrometry). Isolates encompassed end-members allochthonous...
Northern permafrost soils store a vast reservoir of carbon, nearly twice that the present atmosphere. Current and projected climate warming threatens widespread thaw these frozen, organic carbon (OC)-rich soils. Upon thaw, mobilized OC in dissolved particulate forms can enter streams rivers, which are important processors conduits for dioxide (CO2) to Here, we demonstrate ancient (DOC) leached from 35,800 y B.P. is rapidly mineralized CO2. During 200-h experiments novel...
Northern high-latitude rivers are major conduits of carbon from land to coastal seas and the Arctic Ocean. warming is promoting terrestrial permafrost thaw shifting hydrologic flowpaths, leading fluvial mobilization ancient stores. Here we describe (14)C (13)C characteristics dissolved organic networks across Kolyma River Basin (Siberia), isotopic changes during bioincubation experiments. Microbial communities utilized (11,300 >50,000 years) in waters millennial-aged (up 10,000 headwater...
As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release offset by increased production Arctic boreal biomass; however, lack robust estimates net balance increases risk further overshooting international emissions targets. Precise empirical or model-based assessments critical factors driving are unlikely in near future, so address gap, we present from 98...
Abstract Northern rivers connect a land area of approximately 20.5 million km 2 to the Arctic Ocean and surrounding seas. These account for ~10% global river discharge transport massive quantities dissolved particulate materials that reflect watershed sources impact biogeochemical cycling in ocean. In this paper, multiyear data sets from coordinated sampling program are used characterize organic carbon (POC) nitrogen (PN) export six largest within pan‐Arctic (Yenisey, Lena, Ob', Mackenzie,...
Abstract. As Arctic regions warm and frozen soils thaw, the large organic carbon pool stored in permafrost becomes increasingly vulnerable to decomposition or transport. The transfer of newly mobilized atmosphere its potential influence upon climate change will largely depend on degradability delivered aquatic ecosystems. Dissolved (DOC) is a key regulator metabolism, yet knowledge mechanistic controls DOC biodegradability currently poor due scarcity long-term data sets, limited spatial...
We review the published results on Congo Basin hydrology and summarize historic ongoing research. Annual rainfall is ~1900 mm/yr along an east-west trend across basin, decreasing northward southward to ~1100 mm/yr. Historic studies using lysimeters, pans, models suggest that annual potential evapotranspiration varies little basin at 1100 1200 Over past century, river discharge data have been collected hundreds of stream gauges with recent 96 locations now publicly available. River...