Supply, Bioavailability, and Source of Dissolved Organic Carbon in a Prairie Stream PDF Download

Author: Jessica J. Eichmiller
Publisher:
ISBN:
Category :
Languages : en
Pages : 174

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Author: Sophie Alexandra Higgs
Publisher:
ISBN:
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.

Author: Udit Minocha
Publisher:
ISBN:
Category : Carbon
Languages : en
Pages : 122

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Author: J. David Allan
Publisher: Springer Nature
ISBN: 3030612864
Category : Science
Languages : en
Pages : 485

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Stream Ecology: Structure and Function of Running Waters is designed to serve as a textbook for advanced undergraduate and graduate students, and as a reference source for specialists in stream ecology and related fields. This Third Edition is thoroughly updated and expanded to incorporate significant advances in our understanding of environmental factors, biological interactions, and ecosystem processes, and how these vary with hydrological, geomorphological, and landscape setting. The broad diversity of running waters – from torrential mountain brooks, to large, lowland rivers, to great river systems whose basins occupy sub-continents – makes river ecosystems appear overwhelming complex. A central theme of this book is that although the settings are often unique, the processes at work in running waters are general and increasingly well understood. Even as our scientific understanding of stream ecosystems rapidly advances, the pressures arising from diverse human activities continue to threaten the health of rivers worldwide. This book presents vital new findings concerning human impacts, and the advances in pollution control, flow management, restoration, and conservation planning that point to practical solutions. Reviews of the first edition: ".. an unusually lucid and judicious reassessment of the state of stream ecology" Science Magazine "..provides an excellent introduction to the area for advanced undergraduates and graduate students..." Limnology & Oceanography "... a valuable reference for all those interested in the ecology of running waters." Transactions of the American Fisheries Society Reviews of the second edition: "Overall, a must for the field centre and a good starter text in stream ecology." (TEN News, October, 2007) "Highly recommended. Upper-division undergraduates through faculty." (P. R. Pinet, CHOICE, Vol. 45 (7), 2008) "... a very good, fluidly readable book which contains the latest key scientific knowledge of the ecology of running waters." (Daniel Graeber, International Review of Hydrobiology, Vol. 94 (2), 2009)

Author: Martha Mason Griffith
Publisher:
ISBN:
Category :
Languages : en
Pages : 214

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Author: My-Linh T. Nguyen
Publisher:
ISBN:
Category : Arid regions
Languages : en
Pages : 480

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Author: Christine McLaughlin
Publisher:
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Category :
Languages : en
Pages : 202

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Author: William V. Sobczak
Publisher:
ISBN:
Category :
Languages : en
Pages : 488

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Author: Matthew Charles Glenn O'Connell
Publisher:
ISBN:
Category : Forest ecology
Languages : en
Pages : 190

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Author: Danielle Cioce
Publisher:
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Category :
Languages : en
Pages :

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The Bryan/College Station (B/CS) region has been reported to have elevated concentrations of dissolved organic carbon (DOC) in surface water. Increased DOC concentrations are worrisome as DOC has been shown to be an energy source for the recovery and regrowth of E. coli and many watersheds are impaired by high bacteria levels. To examine the sources and fates of DOC in rural and urban regions to better understand DOC movement though the environment, seven watersheds were studied. To investigate source, streams were analyzed using diffuse reflectance near infrared spectroscopy (DR-NIR) and carbon isotopes. Fate of DOC was determined through monthly streams samples, gathered between March 2011 and February 2012, which were incubated for biodegradable DOC (BDOC). Soil in the region was sampled based on land use categories. Soil was analyzed for DOC and BDOC as well as DOC adsorption, the other major fate of DOC. Above ground vegetation was sampled in conjunction with soil and analyzed for BDOC. Data indicated that fecal matter from cliff swallows provided considerable organic material to streams in the B/CS region as shown through DR-NIR. Carbon isotope values in streams ranged from -23.5 +/- 0.7% to -26.8 +/- 0.5%. Stream spectra may be able to predict carbon isotope values in streams (Adj. R2 = 0.88). Mean annual stream DOC concentrations ranged from 11 +/- 3 mg/L to 31 +/- 12 mg/L, which represents a significant decrease in DOC between 2007 and 2011. Concurrent increases in pH and conductivity were also recorded. The decrease in DOC and the increases in pH and conductivity may be due to impacts of high sodium irrigation tap water. Biodegradable DOC was low in streams, which is likely due to DOC being present in streams in refractory forms that are resistant to microbial breakdown. Soil chemistry, including soil adsorption, was greatly influenced by sodium. The elevated adsorption coefficients and release values seen in highly developed and urban open areas can be attributed to frequent exposure to high sodium irrigation water. The results indicate that sodium is a major driver of DOC in the system. Sound management decisions concerning irrigation water chemistry and urban development might eventually emerge to protect water quality as a result of this research.