Author: Publisher:
ISBN:
Category : Neches River (Tex.)
Languages : en
Pages : 93
Book Description
Organic Carbon Dynamics of the Neches River and Its Floodplain
Author: Dissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 868
Book Description
Carbon Dynamics on Floodplains of the Yangtze and Mekong Rivers
Author: Benjamin L. MillerPublisher:
ISBN:
Category :
Languages : en
Pages : 182
Book Description
The lateral expansion and contraction of rivers across their floodplains inextricably links aquatic and terrestrial ecosystem processes for part of each year, yet our understanding of the ecological responses to this seasonal hydrologic forcing is distinctly incomplete. The Flood Pulse Concept (FPC) predicts how in-situ primary production and respiration respond to this forcing. Although many of its predictions remain untested, the FPC is highly-cited and continues to guide hypotheses of ecosystem studies in tropical and subtropical flood-pulse rivers. In Chapter 1 of this dissertation, I reviewed the literature published from 1989 to 2019 on tropical rivers to provide an updated narrative of how primary production and respiration change in response to the seasonal flood-pulse. The literature shows that the in-situ respiration of a combination of aquatic and terrestrial organic carbon (C) exceeds primary production in tropical and subtropical flood-pulse rivers (i.e.,ecosystems are net heterotrophic). For the remainder of the dissertation, I propose that this net heterotrophy changes in response to flood-pulse hydrology and is sustained by both aerobic and anaerobic metabolism, contributing to the composition of dissolved C gases in water, atmospheric emissions of C gases, and the energetic base of aquatic food webs. I further propose that such cycling of C in flood-pulse rivers is fundamentally changed by hydropower development, which alters the magnitude and timing of the seasonal flood-pulse. A central theme that has emerged from the dissertation research presented here is the importance of anaerobic metabolism, specifically CH4 production and oxidation, within inland waters. Anaerobic metabolism has been largely ignored in studies of aquatic C cycling and ecosystem metabolism, with implications for C accounting in other flood-pulse and anaerobic ecosystems, worldwide. Collectively, this work demonstrates that CH4 production and oxidation contribute significantly to CO2 oversaturation, atmospheric C fluxes, and aquatic biota, challenging existing assumptions about terrestrial-aquatic transfers, net heterotrophy, and food web support within flood-pulse rivers and lakes.
Dissolved Organic Carbon Dynamics in the Upper Hudson River Basin
Author: Jennifer A. VaughnDissolved Organic Carbon Dynamics in Lakes and Streams in Northern Wisconsin
Author: Vanessa CzeszynskiPublisher:
ISBN:
Category : Aquatic ecology
Languages : en
Pages : 0
Book Description
Dissolved organic carbon (DOC) is naturally occurring; however, various aspects of global climate change are increasing anthropogenic DOC in freshwater systems. Here we focus on lakes and streams in the Northern Lakes and Forests region of Wisconsin. This study aimed to 1) determine DOC concentration and composition in these systems, 2) compare DOC dynamics between system types and each month sampled, and 3) determine if relationships exist between DOC and nutrient quantities and microbial community production. This study found that DOC ranged from 2.62 - 61.35 mg/L, with no differences in DOC concentrations between the system types or months sampled. However, DOC composition differed greatly between system type and months, with lakes having more autochthonous carbon and streams having more allochthonous carbon (p
Dissolved Organic Carbon Dynamics in a Small Stream
Author: Carole-Jay CiaioPublisher:
ISBN:
Category : Carbon cycle (Biogeochemistry)
Languages : en
Pages : 86
Book Description
Studies the relationship between flow rate and Dissolved Organic Carbon (DOC) in Chillisquaque Creek ("a weak positive relationship") and that between rainstorms, flow rate and DOC (significant).
Riverine Floodplain Heterogeneity as a Controller of Organic Matter Dynamics and Terrestrial Invertebrate Distribution
Author: Simone Daniela LanghansPublisher:
ISBN:
Category :
Languages : en
Pages : 161
Book Description
Dissolved Organic Carbon Dynamics in Urban and Desert Stream Ecosystems
Author: Jennifer EdmondsPublisher:
ISBN:
Category : Carbon cycle (Biogeochemistry)
Languages : en
Pages : 370
Book Description
Carbon Dynamics in the Hyporheic Zone of a Headwater Mountain Stream in the Cascade Mountains, Oregon
Author: Hayley A. Corson-RikertPublisher:
ISBN:
Category : Carbon cycle (Biogeochemistry)
Languages : en
Pages : 114
Book Description
This study investigated carbon dynamics in the hyporheic zone of a steep, forested catchment in the Cascade Mountains of western Oregon, USA. Water samples were collected monthly from a headwater stream and well network during baseflow conditions from July to December 2013 and again in March 2014. We also sampled during one fall storm event, collecting pre-storm, rising leg, and extended high flow samples. The well network is located at the base of Watershed 1 (WS1) of the H.J. Andrews Experimental Forest and spans the full width of the floodplain (~14 m) along a 29 m reach of stream. We measured pH, temperature, water level, major anions, major cations, DOC, DIC, and total alkalinity. Flow paths, travel time to wells and hydraulic conductivity were available from previous studies. During baseflow periods, hyporheic DOC decreased with median travel time through the subsurface. DIC concentrations increased with travel time, but the magnitude of this increase in DIC was too large to be explained by metabolism of stream water DOC. This suggests that there are additional sources of DIC and/or DOC in the subsurface, and that hyporheic DIC concentrations are not well linked to stream-source DOC. The most likely supplemental sources of DIC to hyporheic water are soil CO2 and microbial respiration of DOC leached from buried particulate organic matter and from overlying soils. Overall, the hyporheic zone appears to be a source of DIC to the stream. In summer, the hyporheic zone is likely isolated from vertical infiltration or lateral inflow of soil water, and particulate organic carbon is not present in stream water. Thus, spatial patterns in hyporheic zone biogeochemistry must result from underlying spatial patterns in hyporheic flowpaths, groundwater inputs, and buried particulate organic carbon. With the transition to the rainy season throughout the fall and early winter, vertical infiltration and leaching of accumulated solutes from the overlying soil appear to become important sources of carbon that help explain patterns in hyporheic zone biogeochemistry. During a small November storm event, DOC and nitrate concentrations in the stream displayed clockwise hysteresis. Travel time appeared to be associated with both nitrate and DOC response patterns in the hyporheic zone. In wells with long travel times, DOC and nitrate concentrations showed a clockwise hysteresis pattern that mimicked and even exceeded that observed in the stream. We hypothesize that these solutes were flushed from overlying soils into the hyporheic zone via vertically infiltrating rainwater. In wells with short travel times, we observed only a small peak in DOC and nitrate concentrations during the storm, potentially due to lateral infiltration of stream water later in the event. Overall, temporal patterns in hyporheic solute chemistry during the November storm differed from patterns we observed in the well network. This suggests that whole-watershed processes that controlled stream water chemistry during this storm event were different than those that controlled solute concentrations in the hyporheic zone. Nonetheless, the hyporheic zone must have been linked to the stream. That measurements in our well network reveal a very different response between the stream and the hyporheic zone suggests that: 1) Our hyporheic zone is not representative of stream-hyporheic riparian processes that occur within the larger watershed, or 2) Hillslope-stream or within-stream processes dominate during storms, and at these times the influence of the hyporheic zone on the stream is much weaker than during baseflow. During both baseflow and storm periods, the hydrology of the WS1 system is complex - hyporheic exchange flows follow extended, non-linear flow paths through a heterogeneous subsurface and may be augmented by lateral inflows of groundwater and, during storms, vertical infiltration of soil water. Our results from both baseflow and storm sampling suggest that a complex set of physical mechanisms and biogeochemical processes influence carbon transport and transformation within this hyporheic environment.
Linking Seasonal and Spatial Stream Carbon Dynamics to Landscape Characteristics in Selected Watersheds on the Olympic Peninsula
Author: Roxana RautuPublisher:
ISBN:
Category :
Languages : en
Pages : 53
Book Description
Understanding the factors that affect freshwater export of terrestrially derived carbon is key to creating a comprehensive model of stream ecology and to developing an accurate carbon budget. Though efforts have been made to quantify carbon in Pacific Northwest forests, little is known about the carbon in their freshwater systems. To begin informing this knowledge gap, we collected dissolved organic carbon (DOC) and water quality data along the stream networks of four small, fish-bearing watersheds in the Olympic Experimental State Forest on the Olympic Peninsula, WA during the summer and fall of 2018. Conditional reference random forest models were used to explore how landscape characteristics and climatic variables affect the spatial and temporal variability of carbon composition and water quality parameters. We found that slope-related variables and precipitation were the primary drivers of carbon export. The strengths and magnitudes of these relationships were different for the summer and fall. We also identified two pools of different carbon composition that were present in three of the four study watersheds. The results of this study give us a first look at the drivers of carbon export and the quantity and quality of carbon being exported through freshwater systems. Our work also advises on the spatial and temporal considerations of stream carbon monitoring. We identify three key questions to pursue in future studies that will improve our understanding of stream carbon on the Olympic Peninsula and allow us to monitor it going forward. Our results indicate that future research should explore seasonal variability, hyporheic influences, and management impacts on carbon dynamics.