SFS Annual Meeting

5/23/2018  |   09:00 - 09:15   |  321

BIOAVAILABILITY OF DISSOLVED ORGANIC MATTER IN A CYANOBACTERIAL BLOOMING LAKE AND INPACTS ON EMERGING CONTAMINANT BEHAVIOUR Cyanobacterial blooms frequently occur in eutrophic freshwater lakes, subsequently, substantial amounts of dissolved organic matters (DOM) are produced. The laboratory four-stage plug-flow bioreactor was developed and successfully separated the cyanobacteria-derived DOM isolated from the eutrophic freshwater lake into continuum classes of bioavailable compounds. The results showed that the total loss of 79% of dissolved organic carbon over time was accompanied by depletion of protein-like fluorescent components, especially the relatively hydrophilic ones. Consistently, ultrahigh resolution mass spectrometry (FT-ICR-MS) revealed that smaller, less aromatic, more oxygenated, and nitrogen-rich molecules were preferentially consumed by microorganisms with the production of lipid-like species, whereas recalcitrant molecules were primarily composed of carboxylic-rich alicyclic compounds. In addition, the bioavailability of DOM was negatively correlated with microbial community diversity in the bioreactor. Moreover, the bioavailability of DOM was found to affect the behavior of emerging contaminates in lakes, and recalcitrant components could stimulate the biodegradation of emerging contaminates. Results from this study provide deeper insights into the relevant biogeochemical processes of cyanobacteria-derived DOM and impact on the fate of emerging contaminant in eutrophic lakes.

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


Leilei Bai (Co-Presenter/Co-Author), Nanjing Institute of Geography and Limnology, xiaobai003@163.com;


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5/23/2018  |   09:15 - 09:30   |  321

EXPLORING SPATIOTEMPORAL VARIATION IN STREAM DISSOLVED ORGANIC MATTER TO BETTER UNDERSTAND HYDROECOLOGICAL REGIMES IN A MONTANE, URBANIZING WATERSHED Headwater streams integrate chemical outputs of adjacent terrestrial ecosystems, and high-elevation watersheds are sensitive to climate and land-use influences. Dissolved organic matter (DOM) composition in stream water reflects an aggregation of biogeochemical flux; thus, variations in its character may inform understanding of stream spatiotemporal processing patterns. We explored the potential for signals in DOM fluorescence and molecular composition to represent hydroecological processing regimes in montane headwater streams over hourly, seasonal, and inter-annual resolutions. We expected the contribution of locally derived DOM during the algal growing season (summer through autumn) would be controlled largely by stream biomass production, which is influenced by initial scouring snowmelt flow, time of day, and nutrient loading. Terrestrial DOM signatures were observed continuously, describing a dominant hydrologic connection throughout watershed compartments. DOM composition and reactivity fluctuated spatially and within diel cycles; this variation was not apparent using an overall PARAFAC fluorescent model approach, therefore supplementary comparative models were considered. Variation in DOM composition appeared to be a function of local processes and nighttime biogeochemical processing. This work contributes a useful approach toward using spatiotemporal variation in DOM composition to infer the hydroecological regimes of watershed ecosystems.

Juliana D'Andrilli (Primary Presenter/Author), Montana State University, juliana@montana.edu;


Meryl Storb (Co-Presenter/Co-Author), USGS WY-MT Water Science Center, mstorb@usgs.gov;


Robert Payn (Co-Presenter/Co-Author), Montana State University, Montana Institute on Ecosystems, rpayn@montana.edu;


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5/23/2018  |   09:30 - 09:45   |  321

CONCENTRATION AND COMPOSITION OF DISSOLVED ORGANIC MATTER IN TEMPORARY DEPRESSIONAL WETLANDS ON THE DELMARVA PENINSULA VARY BETWEEN WETLANDS AND SEASONS Small, seasonally inundated depressional wetlands occur throughout the Delmarva Peninsula. Many form surface connections to perennial streams when inundated, exporting water and materials that may affect stream ecosystem structure or function. These wetlands are known to contain high concentrations of dissolved organic carbon (DOC) in the form of dissolved organic matter (DOM), but this material has not been characterized in detail. Understanding variation in DOM between wetlands and between seasons is necessary to understand the role of DOM in carbon cycling in these wetlands, and is the basis of understanding the potential impact of DOM exports on stream ecosystems. We describe spatial and temporal variability in DOC concentrations and optical properties of surface water DOM in 20 wetlands distributed across a small area (<1600 hectares). Additionally, we report the likely molecular formulae of solid phase extracts from several wetlands. DOC concentrations varied between wetlands and through time (from 10 to over 40 mg/L). Canopy cover or wetland size may explain seasonal differences in optical properties. Delmarva wetland DOM resembles material described elsewhere as terrestrially-derived and humic, but the variation here presents opportunities to refine ecological implications within these categories.

Margaret Palmer (Co-Presenter/Co-Author), National Socio-Environmental Synthesis Center, mpalmer@sesync.org;


Michael Gonsior (Co-Presenter/Co-Author), Chesapeake Biological Laboratory , gonsior@umces.edu;


Alec Armstrong (Primary Presenter/Author), University of Maryland, aarmstrong@mica.edu;


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5/23/2018  |   09:45 - 10:00   |  321

ACTIVE TRANSFORMATION OF NATURAL DISSOLVED ORGANIC MATTER REGULATED BY SIZE AND COMPOSITION Dissolved organic matter (DOM) plays an important role in regulating water quality, ecological function, and the fate and transport of trace elements and pollutants in aquatic environments. Natural DOM samples were incubated in dark for 21 days to examine dynamic changes in molecular size and composition induced by microbial degradation and self-assembly. Results showed that the concentrations of total organic carbon, carbohydrates, and protein-like substances decreased during incubation, while those of humic- and fulvic-like substances remained relatively constant, indicating humic substances are more resistant to microbial utilization compared to carbohydrates and protein-like DOM. Despite the different extents in decline, these DOM components had a similar transformation pathway from the <1 kDa to colloids (1 kDa–0.45 ?m) and further to microparticles (>0.45 ?m). Overall, carbohydrates and protein-like substances, especially the high molecular weight components, were preferentially decomposed by microorganisms whereas humic- and fulvic-like DOM components significantly coagulated through abiotic self-assembly. The contrasting degradation/transformation pathways between the humic-like and protein-like substances along the size continuum, as also characterized by flow field-flow fractionation analysis, demonstrated that the dynamic transformation and degradation of DOM is regulated by both molecular size and organic composition.

Huacheng Xu (Primary Presenter/Author), Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, hcxu@niglas.ac.cn;


Laodong Guo (Co-Presenter/Co-Author), School of Freshwater Sciences, University of Wisconsin-Milwaukee, guol@uwm.edu;


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5/23/2018  |   10:00 - 10:15   |  321

THE FATE OF TERRESTRIALLY DERIVED DISSOLVED ORGANIC MATTER IN ONE SUB-TROPICAL AND THREE TEMPERATE LAKES OF VARYING TROPHIC STATUS Freshwater ecosystems outgas a substantial quantity of carbon dioxide (CO2). The processing of dissolved organic matter (DOM) by biodegradation and photodegradation can result in the release of CO2, but the relative importance of these two processes is poorly understood. In contrast to previous findings, recent research in Arctic lakes and streams found that photodegradation was more important than biodegradation in the oxidation of terrestrially-derived DOC to CO2. We studied three temperate lakes ranging in trophic status (dystrophic, eutrophic, and oligotrophic) and one sub-tropical lake (dystrophic) to assess the relative importance of biodegradation vs. photodegradation in oxidizing DOC to CO2. We also assessed changes in dissolved oxygen, color, and spectral slope during the experiments. We found photodegradation was the dominant process in all lakes, but its importance varied with lake trophic status. When exposed to sunlight, DOC from the dystrophic lakes (temperate and sub-tropical) produced measurable quantities of CO2, whereas DOC from the eutrophic and oligotrophic lake exhibited a stronger response in their optical characteristics. Our results indicate sunlight is an important degradation process, but the amount of CO2 released varies with the trophic status of the lake.

Jennifer Brentrup (Co-Presenter/Co-Author), Dartmouth College, Department of Biological Sciences, Jennifer.A.Brentrup@dartmouth.edu;


Sarah Magyan (Co-Presenter/Co-Author), Gannon University, Biology Department, magyan001@knights.gannon.edu;


Lesley Knoll (Co-Presenter/Co-Author), University of Minnesota, Itasca Biological Station and Laboratories, lbknoll@umn.edu;


Craig Williamson (Co-Presenter/Co-Author), Miami University, Global Change Limnology Laboratory, Department of Biology, willia85@miamioh.edu;


Chris Dempsey (Primary Presenter/Author), Gannon University, Biology Department, dempsey007@gannon.edu;


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