Author: Keith Thomas CialinoPublisher:
ISBN:
Category : Neponset River Watershed (Mass.)
Languages : en
Pages : 576
Book Description
Fluxes of Dissolved Organic Carbon During Storm Events in the Neponset River Watershed
Author: Keith Thomas CialinoPublisher:
ISBN:
Category : Neponset River Watershed (Mass.)
Languages : en
Pages : 576
Book Description
Dissolved Organic Carbon and Nitrogen Dynamics in a Pristine Old Growth Forested Watershed with Anthropogenic Nitrogen Deposition
Author: Christopher AmyotPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
"Forested watersheds play an important role in the transformation of nitrogen (N) and carbon (C) as they pass from atmospheric inputs to aquatic ecosystems, under diverse anthropogenic nitrogen deposition and land cover regimes. In this study, I examined the transformations of dissolved organic carbon (DOC), ammonium (NH4), nitrate (NO3), and dissolved organic nitrogen (DON) from precipitation inputs through the forest canopy, into the well-drained and wetland soils, and into two streams draining a 46 ha and a 11 ha nested old growth forested watersheds at Mont St. Hilaire (MSH), in southern Quebec. Measurements were made from May to September 2013, with sampling at one-week intervals and during storm events. Concentrations and fluxes of DOC, NH4, and DON increased from the atmosphere to throughfall, and decreased as water passed through the upland mineral soils and wetlands to the stream, while NO3 showed no change. Transformations of DON occurred as water passed through persistently saturated areas within the wetland and surrounding the stream, resulting in biogeochemical hotspots, where DON concentrations significantly decreased. DOC did not respond these locations, yet is positively correlated to DON and increased water depth. Yearly estimated inputs through the forest canopy were 4.04 kg/ha/yr, 5.61 kg/ha/yr, 3.14 kg/ha/yr, and 79.41 kg/ha/yr for NO3, NH4, DON and DOC. Overall, N retention rates from atmospheric input to stream output were 90 % and 91 % for DON and for a combined NO3 and NH4 input-output measure, while DOC inputs were five times greater than outputs. NO3 was retained less during saturated soils conditions and DON showed slightly more retention at the beginning of the growing season. When compared to other studies with low nitrogen, MSH, showed no similarities in retention or output. Studies with high nitrogen deposition and past disturbance did compare with NO3 and NH4 retention results for MSH, however, hydrological DOC inputs-outputs, at MSH, when compared to other high nitrogen sites with anthropogenic disturbance differed, showing five times more DOC input than output, compared to two times more output than input for the disturbed sites. These findings help to define the present day N and C dynamics in an old growth forest with anthropogenic nitrogen deposition, and provide a comparison for future environmental changes and to conservation and natural resource managers during the restoration and protection of forested watersheds. " --
Ephemeral Organic Carbon Fluxes to the Chesapeake Bay from Agricultural Runoff on the Virginia Coastal Plain
Author: Emma Katherine CaverlyPublisher:
ISBN:
Category :
Languages : en
Pages : 46
Book Description
Dissolved organic carbon (DOC) and particulate organic carbon (POC) play a critical role in nutrient cycling, contaminant transport and the global carbon cycle, but total organic carbon (TOC) fluxes are not well constrained across different land uses and environments. We use automated high resolution sampling of agricultural storm runoff and stream height to quantify DOC and POC fluxes and dynamics in an ephemeral channel on the coastal plain of Virginia. DOC and POC were characterized using specific UV absorbance (SUVA254). During a two week period when a hurricane and tropical storm passed over the region, we measured a DOC flux of 22 kg ha-1 and a POC flux of 11.3 kg ha-1. SUVA254 values indicated that the aromatic portion of DOC ranged from a minimum 18.6% at the beginning of the first event to a maximum of 44.0% during the second event; this represents an increase in soil derived DOC. Hysteresis plots and SUVA254 indicated that plant derived aliphatic DOC was depleted while soil sourced aromatic DOC was readily available. Ephemeral can facilitate the export of large quantities of organic carbon during flashy, storm generated flows.
Dissolved Organic Carbon Dynamics During the Snowmelt Period in a Small Urban Watershed
Author: Jaclyn L. O'RileyPublisher:
ISBN:
Category : Neponset River (Mass.)
Languages : en
Pages : 240
Book Description
Changes in Fluxes of Dissolved Organic Carbon (DOC) from Small Catchments in Central Scotland
Author: Catherine Louise WearingPublisher:
ISBN:
Category : Acid deposition
Languages : en
Pages :
Book Description
Concentrations of dissolved organic carbon (DOC) measured within water bodies have been increasing on a global scale over the last two decades. Changes in temperature and rainfall have been shown to increase the production and export of DOC from catchments with peat soils in the UK (Freeman et al., 2001). However it is not clear whether increases in DOC concentrations are caused by production increases induced by temperature changes or by a greater incidence of high flows induced by rainfall changes. Increases in both temperature and rainfall have been predicted in Scotland over the next few decades (Kerr et al., 1999) which may further increase current DOC concentrations and exports. The implications of this include both a decrease in water quality and an increase in mobility of metals in upland water bodies. The overall aim of the thesis is to determine if the relationship between dissolved organic carbon (DOC) concentrations and discharge has changed over a 20 year period in small stream catchments in Scotland, in order to better understand the role of hydrology, in driving changes in DOC concentration. To achieve this streams draining two coniferous forest sites and one moorland site were monitored intensively between June 2004 and February 2006. Analysis of the relationship between DOC and discharge, within the catchments, identified the importance of the amount of precipitation falling on the catchment, antecedent precipitation and season, on the concentration of DOC that was measured within the stream. Models were then developed using variables to represent these drivers in terms of both the production (seasonal sine values and 14 day average temperatures) and movement (log of discharge (log Q), days since previous storm event and rising or falling stage) of DOC. In the Ochil Hills catchment, the best predictive model, used 4 hour average discharge and 1 day average 30cm soil temperatures (R2= 0.88). In the Duchray and Elrig catchments, the best predictive models produced used discharge and seasonal sine values; the strength of the model was greater in the Elrig (R2= 0.80) than the Duchray (R2= 0.48) catchment. The strength of the regression models produced highlighted the importance of precipitation in the movement of DOC to the stream and temperature variables representing production in the surrounding catchment. To determine if dissolved organic carbon (DOC) concentrations had changed within the three study catchments, since previous research was conducted at the same sites in the early 1980s and 1990s (Grieve, 1984a; Grieve, 1994), then regression analysis conducted in the previous research was repeated, so changes in the DOC and discharge relationship could be identified. Analysis of the Ochil Hills regression equations identified higher log of discharge and lower temperature and seasonal sine values in the present study (2004-06), when compared to the previous study (1982-83). This suggests that more DOC is now available for movement from the soil, and that the difference between winter and summer DOC production has decreased, potentially because of increasing temperatures. This would explain the limited increase in DOC concentration within the Ochil Hills stream. In the Duchray and Elrig streams, a large increase in DOC was identified at all discharges when all the models produced were compared between the two sampling periods (1989-90 and 2004-06). The increasing trend in DOC concentrations is too large to have been produced by change in temperature alone and it is suggested that the measured reduction in acidic deposition has resulted in the increased DOC concentrations measured in the Duchray and Elrig. The results from this research have identified that concentrations of DOC have increased in Scottish streams over the last 20 years and that the increases in DOC have been induced, potentially by temperature changes in climate. However, changes in temperature are not the only driver of this change as the reduction in acidic deposition is potentially more important, specifically in areas with base poor geology such as the Duchray and Elrig catchments.
Fluxes of Dissolved Organic Matter from Urban Catchments in the Neuse River Basin
Author: Sarah Ellen JohnstonAquatic Organic Matter Fluorescence
Author: Paula G. CoblePublisher: Cambridge University Press
ISBN: 0521764610
Category : Science
Languages : en
Pages : 407
Book Description
A core text on principles, laboratory/field methodologies, and data interpretation for fluorescence applications in aquatic science, for advanced students and researchers.
Sources, Sinks, and Fluxes of Dissolved Organic Carbon in Subarctic Fen Catchments
Author: Jean-François KoprivnjakPublisher:
ISBN:
Category : Carbon cycle (Biogeochemistry)
Languages : en
Pages : 180
Book Description
"DOC concentrations in streams draining ten fen catchments were found to be positively correlated with the percentage of fen area in the catchments." --
Aquatic Ecosystems: Interactivity of Dissolved Organic Matter
Author: Stuart FindlayPublisher: Academic Press
ISBN: 0122563719
Category : Nature
Languages : en
Pages : 534
Book Description
Overviews of the source, supply and variability of DOM, surveys of the processes that mediate inputs to microbial food webs, and syntheses consolidating research findings provide a comprehensive review of what is known of DOM in freshwater. This book will be important to anyone interested in understanding the fundamental factors associated with DOM that control aquatic ecosystems."--BOOK JACKET.
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