Dissolved Organic Carbon Dynamics During the Snowmelt Period in a Small Urban Watershed PDF Download

Author: Jaclyn L. O'Riley
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Category : Neponset River (Mass.)
Languages : en
Pages : 240

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Author: Hannah Nicole Checketts
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Category :
Languages : en
Pages : 33

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Snowmelt river systems exhibit seasonal fluxes in water chemistry, potentially affecting the water supply of one-sixth of the world’s population. In this study, we examined water chemistry of the upper Provo River, northern Utah, which supplies water to over two million people along the urban Wasatch Front. Seasonal changes in water chemistry were characterized by analyzing discharge and dissolved organic carbon (DOC with dissolved trace metal and cation concentrations (La, Pb, Cu, Al, Be, Sr and K over three consecutive water years 2014―2016, with intensive sampling during snowmelt runoff. To better understand links between metal movement and DOC, we sampled the river in three locations (Soapstone, Woodland, and Hailstone, snowpack, and ephemeral snowmelt channels. Concentrations of La, Pb, Cu, Al, and Be increased with discharge/snowmelt during the 2014, 2015 and 2016 water years. Over 90% of La, Pb, Cu, Al, Be and between 70-90% Sr and K loads occurred during snowmelt season (April-June. In relation to discharge, concentrations of each element varied between the river sampling sites. At Soapstone, DOC, La, Pb, Cu, Al and Be increased slightly with discharge, but Sr and K remained chemostatic. At Woodland and Hailstone, DOC, La, Pb, Cu, Al and Be had sharp increases with discharge, and Sr and K were diluted. Hysteresis patterns showed that concentrations of DOC, La, Pb, Cu, Al, Be, Sr and K all peaked on the rising limb of the hydrograph at the higher elevation Soapstone site but patterns were variable at the lower elevation Woodland and Hailstone sites. Concentrations for ephemeral channels were significantly higher than river and snow concentrations in La, Pb, Cu and Al, suggesting soil water was a significant source of flushed metals and DOC to the upper Provo River. DOC was highly correlated with La (R2 = 0.94, P =

Author: Jennifer Edmonds
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Category : Carbon cycle (Biogeochemistry)
Languages : en
Pages : 370

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Author: Meyer. J. L.
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Category :
Languages : en
Pages : 12

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Author: Carole-Jay Ciaio
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Category : Carbon cycle (Biogeochemistry)
Languages : en
Pages : 86

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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).

Author: Roxana Rautu
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Category :
Languages : en
Pages : 53

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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.

Author: Keith Thomas Cialino
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Category : Neponset River Watershed (Mass.)
Languages : en
Pages : 576

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Author: Krittika Govil
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Category :
Languages : en
Pages :

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Water quality in urban ecosystems is sensitive to localized disturbances potentially affecting those mechanisms which influence nutrient cycles. The Carters Creek Basin has been reported to have elevated concentrations of dissolved organic carbon (DOC). In combination with high terrestrial nutrient export from non-point sources and point source effluent discharge, this has been suggested to contribute to E.Coli recovery and regrowth. Spatial identification of loading "hot-spots" or locations of elevated nutrient concentrations of non-point, terrestrial sources may provide critical information necessary for appropriate mitigation efforts and watershed management. This study used traditional and novel methods for source tracking nutrients and dissolved organic carbon in small urban and rural watersheds in Brazos County, Texas. A nested watershed approach allowed identification of problem areas of nutrient loading. A novel cost-effective technique using diffuse reflectance near-infrared spectroscopy was used to identify sources of DOC. Monthly stream sampling was conducted at 12 sites from 2012 to 2013. Impacts of human activity on landscape features determining source pathways for nutrient retention, transport, and conversion were identified in this study. Higher nitrate-N (0.12-22.8 mg L−1), orthophosphate-P (0.11-3.60mgL−1), and DOC concentrations (18.6-68.1 mg L−1) were found across the watershed than in 2007. Factors such as increased erosion, sodic soil dispersion, land use, and flow conditions wereidentified as possible causes for increased carbon (C), nitrogen (N) and phosphorus (P) observed in the basin. This study supported the use of near-infrared spectroscopy to elucidate watershed sources of carbon. The major sources of DOC into the Carter Creek basin watersheds were leachate from soil and turfgrass. Rural subwatersheds had less complicated source signatures than their urban counterparts. Urban impervious runoff signatures also clustered with stream water signatures, especially during high flow in October and September. These results indicate that specific vegetation such as turfgrass used for landscapes in urban watersheds coupled with sodic irrigation may alter traditional nitrogen, phosphorus and carbon cycling in urbanizing watersheds. Spatial source tracking will enable efficient pollution mitigation and protect water quality as a result of this study. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/152459

Author: Christopher Amyot
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Category :
Languages : en
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"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. " --

Author: Sophie Alexandra Higgs
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Category :
Languages : en
Pages :

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Contrary to the previous notion that a stream acts primarily as the transporter of materials from land to oceans, research has shown that in-stream processing of organic matter and nutrients is significant and relevant at a global scale. Dissolved organic carbon (DOC) is the most abundant form of organic carbon in streams and has been demonstrated as an important source of energy supporting stream food webs. Understanding the dynamics of DOC in streams is, therefore, important in determining the contribution of flowing waters to global carbon storage and release. However, DOC exists as many different compounds, varying in source, composition, and quality. The composition of DOC that ends up in streams is partly controlled by the surrounding watershed, and landscape effects on DOC quality and quantity in streams have been observed. In the North American Tallgrass prairie, woody encroachment has led to changes in riparian vegetation, potentially altering the DOC received by the stream, and making it important to understand rates of DOC transformation as landscape alterations continue. The heterogeneity of the DOC pool makes it difficult to fully describe its components and to measure transformation rates. DOC uptake, or biological use, has been estimated through several methods including in-stream additions of various DOC sources and bottle incubations of stream water and sediments. One problem with addition methods for calculating uptake is that the DOC pool is difficult to replicate and additions of simple compounds or organic leachates do not represent total dissolved organic carbon (TDOC) dynamics. Another potential issue is that additions of a labile compound could potentially alter microbial activity through a priming effect and therefore distort ambient DOC uptake estimates. Finally, uptake parameters are mostly calculated assuming benthic uptake while recent studies have shown that planktonic uptake of DOC can also be significant. We conducted this study with these three considerations in mind. In the first chapter, we describe our use of in situ additions of glucose and bur oak leaf leachate in prairie stream reaches and concentrations of specific components to determine uptake dynamics of various specific DOC components, from a simple sugar to more complex plant compounds. We calculated uptake parameters of glucose and two different oak leaf components. We found that using glucose concentrations rather than TDOC concentrations, as has been done in previous studies, to measure uptake parameters resulted in higher uptake rates, indicating the importance of measuring the specific component added. Through leaf leachate additions, we found that an amino acid like component was consistently taken up faster than a humic-like component. The second chapter addresses the questions of uptake location and priming through a series of recirculating chamber incubations. We found that benthic uptake of leaf leachate was more important than that in the water column. Finally, elevated uptake of one leaf leachate component in the presence of glucose indicated a priming effect on microbial DOC uptake.