Tuesday, May 19, 2015
10:30 - 12:00

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10:30 - 10:45: / 101B FROM THE HILLSLOPE TO THE STREAM: RAPID TRANSFORMATION OF DISSOLVED ORGANIC MATTER QUALITY IN HEADWATER REACHES OF A MOUNTAIN CATCHMENT

5/19/2015  |   10:30 - 10:45   |  101B

FROM THE HILLSLOPE TO THE STREAM: RAPID TRANSFORMATION OF DISSOLVED ORGANIC MATTER QUALITY IN HEADWATER REACHES OF A MOUNTAIN CATCHMENT Dissolved organic matter (DOM) transport is a key biogeochemical process in headwater catchments. Studies evaluating DOM mobility have indicated that transformations reflect both sorption and microbial uptake. We studied these processes in a semi-arid montane catchment as part of the Boulder Creek Critical Zone observatory. During low flow, we conducted two tracer experiments by injecting water soluble soil organic matter into a headwater stream reach. Downstream changes in DOM quality were followed based on fluorescence spectroscopy. The results indicated rapid transformation and removal of some soil humic fluorophores within the hyporheic zone. During the high-flow, snowmelt period, we monitored DOM quality on a daily basis within the shallow soil (10 – 25 cm depth) and the stream and compared the results to bi-monthly groundwater samples. In the stream, a pronounced transition occurred from fluorescent DOM being dominated by protein-like material to being dominated by more humic-like material. The FDOM in the soil interstitial water and the groundwater did not change in character. These results indicate that hyporheic processes and shifts in hydrologic connectivity are both major controls on DOM quality.

Diane McKnight (Primary Presenter/Author), University of Colorado, diane.mcknight@colorado.edu;


Rachel Gabor (Co-Presenter/Co-Author), University of Colorado, rachel.gabor@colorado.edu;


Margaret Burns (Co-Presenter/Co-Author), University of Colorado, margaret.a.burns1@gmail.com;


Holly Barnard (Co-Presenter/Co-Author), University of Colorado - Boulder, holly.barnard@colorado.edu;


10:45 - 11:00: / 101B FROM THE HILLSLOPE TO THE STREAM: RAPID TRANSFORMATION OF DISSOLVED ORGANIC MATTER QUALITY IN HEADWATER REACHES OF A MOUNTAIN CATCHMENT

5/19/2015  |   10:45 - 11:00   |  101B

FROM THE HILLSLOPE TO THE STREAM: RAPID TRANSFORMATION OF DISSOLVED ORGANIC MATTER QUALITY IN HEADWATER REACHES OF A MOUNTAIN CATCHMENT Dissolved organic matter (DOM) transport is a key biogeochemical process in headwater catchments. Studies evaluating DOM mobility have indicated that transformations reflect both sorption and microbial uptake. We studied these processes in a semi-arid montane catchment as part of the Boulder Creek Critical Zone observatory. During low flow, we conducted two tracer experiments by injecting water soluble soil organic matter into a headwater stream reach. Downstream changes in DOM quality were followed based on fluorescence spectroscopy. The results indicated rapid transformation and removal of some soil humic fluorophores within the hyporheic zone. During the high-flow, snowmelt period, we monitored DOM quality on a daily basis within the shallow soil (10 – 25 cm depth) and the stream and compared the results to bi-monthly groundwater samples. In the stream, a pronounced transition occurred from fluorescent DOM being dominated by protein-like material to being dominated by more humic-like material. The FDOM in the soil interstitial water and the groundwater did not change in character. These results indicate that hyporheic processes and shifts in hydrologic connectivity are both major controls on DOM quality.

Diane McKnight (Primary Presenter/Author), University of Colorado, diane.mcknight@colorado.edu;


Rachel Gabor (Co-Presenter/Co-Author), University of Colorado, rachel.gabor@colorado.edu;


Margaret Burns (Co-Presenter/Co-Author), University of Colorado, margaret.a.burns1@gmail.com;


Holly Barnard (Co-Presenter/Co-Author), University of Colorado - Boulder, holly.barnard@colorado.edu;


11:00 - 11:15: / 101B HG SPECIATION AND PERIPHYTON COMPOSITION MATTER IN HG ACCUMULATION TO PERIPHYTIC COMMUNITIES OF CONTAMINATED RIVER

5/19/2015  |   11:00 - 11:15   |  101B

HG SPECIATION AND PERIPHYTON COMPOSITION MATTER IN HG ACCUMULATION TO PERIPHYTIC COMMUNITIES OF CONTAMINATED RIVER Periphyton is known to play an important role in biogeochemical cycles of nutrients and trace metals such as Hg in freshwaters. Nonetheless, its role in the different processes underlying Hg biogeochemistry cycle is still poorly understood. The present study explores inorganic Hg (IHg) and methymercury (MeHg) speciation, uptake to in-situ grown periphyton and possible linkages with periphyton composition in Olt River (Romania) contaminated by Hg containing effluents from a chloro-alkali production plant. IHg and MeHg contents in water and periphyton were analysed, together with different water quality parameters. Biofilm taxonomic composition was characterized by pyrosequencing. Results showed a decrease of IHg and MeHg concentrations in water and periphyton communities with the distance from the effluent release. IHg in periphyton increased linearly with the concentrations of Hg(OH)2 in water, while enhanced MeHg contents were found in peripyton rich in chlorophyll containing microorganisms. Pyrosequencing analysis revealed the predominance of the phototrophic microorganisms in all sites, followed by bacteria and fungi. The phylum composition was dependent on Hg concentrations in water, with Hg-tolerant phylums predominance in the sites with higher Hg concentrations.

Vera Slaveykova (Primary Presenter/Author), University of Geneva, vera.slaveykova@unige.ch;


Perrine Dranguet (Co-Presenter/Co-Author), University of Geneva, perrine.dranguet@unige.ch;


Séverine Le Faucheur (Co-Presenter/Co-Author), University of Geneva, severine.lefaucheur@unige.ch;


Claudia Cosio (Co-Presenter/Co-Author), University of Geneva, claudia.cosio@unige.ch;


11:15 - 11:30: / 101B THE EFFECT OF RANDOM PARAMETER ERRORS ON PREDICTABILITY OF LONG-TERM CHANGE IN FRESHWATER PCO2 CALCULATED FROM THERMODYNAMIC EQUILIBRIA

5/19/2015  |   11:15 - 11:30   |  101B

THE EFFECT OF RANDOM PARAMETER ERRORS ON PREDICTABILITY OF LONG-TERM CHANGE IN FRESHWATER PCO2 CALCULATED FROM THERMODYNAMIC EQUILIBRIA Most estimates of CO2 evasion from inland waters rely on calculating pCO2 using carbonate equilibria models. Therefore, the quality of input parameters directly influences uncertainty in pCO2 estimates and detection level of pCO2 temporal trends. We used North Temperate Lakes Long Term Ecological Research datasets to quantify random errors in the measurements of pH, alkalinity and dissolved inorganic carbon. Monte Carlo simulations were used to propagate uncertainties into long-term records in parameters and pCO2 calculated from three thermodynamic equilibria models to determine the resultant precision of pCO2 estimates. Random parameter errors were generally below 2% and varied by lake type. Temporal trends in pCO2 differed across lakes and thermodynamic equilibrium model type. Each carbonate equilibrium model showed different sensitivities to random uncertainties and many trends were insignificant. We use model simulations to show the level of pCO2 trend that can be detected for a given precision of input parameters, and the implications for designing a set of acceptable precision criteria. Our results highlight the possible challenges in predicting long-term change in aquatic carbon efflux with existing long-term data.

Malgorzata Golub (Primary Presenter/Author), University of Wisconsin - Madison, mgolub@wisc.edu;


Ankur R. Desai (Co-Presenter/Co-Author), University of Wisconsin - Madison, desai@aos.wisc.edu;


Christina K. Remucal (Co-Presenter/Co-Author), University of Wisconsin - Madison, remucal@wisc.edu;


Galen A. McKinley (Co-Presenter/Co-Author), University of Wisconsin - Madison, gamckinley@wisc.edu;


Emily Stanley (Co-Presenter/Co-Author), University of Wisconsin - Madison, ehstanley@wisc.edu;


11:30 - 11:45: / 101B UTILIZATION AND ENVIRONMENTAL IMPACT OF ORGANIC CARBON FROM CYANOBACTERIAL BLOOM BIOMASS IN A EUTROPHIC LAKE

5/19/2015  |   11:30 - 11:45   |  101B

UTILIZATION AND ENVIRONMENTAL IMPACT OF ORGANIC CARBON FROM CYANOBACTERIAL BLOOM BIOMASS IN A EUTROPHIC LAKE Cyanobacterial blooms frequently occur in eutrophic freshwater lakes, subsequently, substantial amounts of organic carbon are produced. A majority of the algal-derived organic carbon will be utilized by microbial communities in lakes. Bacterial community composition in cyanobacterial phycosphere was highly organized and showed obvious difference from phytoplankton. Furthermore, bacterial communities of different sized aggregates within the cyanobacterial phycosphere varied with dependence on aggregate size. Bacterial species on large and small-size aggregates likely have the ability to degrade high and low molecular weight compounds respectively, possibly operating in sequence and synergy to catalyze the turnover of complex organic matters. In addition, extracellular polymeric substances from bloom-forming cyanobacteria play an important role in the fate of contaminants. After decaying, cyanobacterial bloom biomass settles onto the lake sediments, which led to the occurrence of hypoxia and the release of phosphorus from sediments but improved the degradation of polycyclic aromatic hydrocarbons in sediments. Therefore, organic carbon from cyanobacterial bloom had multi-functions for lake biogeochemistry processes and water environment quality, and thus needs to be considered in the management and remediation of freshwater ecosystems.

Helong Jiang (POC,Primary Presenter), State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing , hljiang@niglas.ac.cn;


11:45 - 12:00: / 101B CLIMACTIC CHANGE IN LAKE MICHIGAN: BIG EVENTS, BASIN-WIDE IMPACT

5/19/2015  |   11:45 - 12:00   |  101B

CLIMACTIC CHANGE IN LAKE MICHIGAN: BIG EVENTS, BASIN-WIDE IMPACT Ecosystem engineering of Lake Michigan by benthic bivalve invaders has exceeded any previous event since human settlement. Dreissenids are not the only force acting upon lake metabolism, however, and both meteorological and human manipulation have also exerted outstanding influences on Lake Michigan structure and function. Much like Keeling's Mauna Loa carbon dioxide data, aspects of lake biogeochemistry contain multi-decadally consistent seasonal cycles upon which major trends or alterations are superimposed. In this work, a focus on geological features interacting with hydrodynamics indicate a major role of the Mid-Lake Reef Complex, a multi-seamount-like structure in south central Lake Michigan, in basin- and even lake-wide ecosystem function. Annual oscillations of dissolved silicate suddenly dampened dramatically following Quagga Mussel establishment, accompanied by major increases in water clarity. Meteorological events including the Great Flood of 2008 produced readily-discernable anomalies. All these are signals on a continuous trend of decreasing biomass and dampened nutrient cycles resulting from decades of phosphorus management. The oligotrophicated water column belies a newly organic-rich benthos different from any of the other Great Lakes of North America.

Russell Cuhel (Primary Presenter/Author), UW-Milwaukee School of Freshwater Sciences, rcuhel@uwm.edu;


Carmen Aguilar (Co-Presenter/Co-Author), UW-Milwaukee School of Freshwater Sciences, aguilar@uwm.edu;