Your browser doesn't support javascript.
loading
Climatic and watershed controls of dissolved organic matter variation in streams across a gradient of agricultural land use.
Shang, Peng; Lu, YueHan; Du, YingXun; Jaffé, Rudolf; Findlay, Robert H; Wynn, Anne.
Afiliação
  • Shang P; Department of Geological Sciences, The University of Alabama, 201 7th Ave, Tuscaloosa, AL 35485, USA.
  • Lu Y; Department of Geological Sciences, The University of Alabama, 201 7th Ave, Tuscaloosa, AL 35485, USA. Electronic address: yuehan.lu@ua.edu.
  • Du Y; Nanjing Institute of Geography and Limnology, State Key Laboratory of Lake Science and Environment, Chinese Academy of Sciences, Nanjing 210008, China; Southeast Environmental Research Center, Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
  • Jaffé R; Southeast Environmental Research Center, Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
  • Findlay RH; Department of Biological Sciences, The University of Alabama, 201 7th Ave, Tuscaloosa, AL 35485, USA.
  • Wynn A; Geological Survey of Alabama, 35401 Tuscaloosa, AL, USA.
Sci Total Environ ; 612: 1442-1453, 2018 Jan 15.
Article em En | MEDLINE | ID: mdl-28903173
Human land use has led to significant changes in the character of dissolved organic matter (DOM) in lotic ecosystems. These changes are expected to have important environmental and ecological consequences. However, high spatiotemporal variability has been reported in previous studies, and the underlying mechanisms remain inadequately understood. This study assessed variation in the properties of stream water DOM within watersheds across a gradient of agricultural land use with grazing pasture lands as the dominant agricultural type in the southeastern United States. We collected water samples under baseflow conditions five times over eight months from a regional group of first- to fourth-order streams. Samples were analyzed for dissolved organic carbon (DOC) concentration, DOM quality based on absorbance and fluorescence properties, as well as DOM biodegradability. We found that air temperature and antecedent hydrological conditions (indicated by antecedent precipitation index and stream water sodium concentrations) positively influenced stream water DOC concentration, DOM fluorescence index, and the proportion of soil-derived, microbial humic fluorescence. This observation suggests that elevated production and release of microbial DOM in soils facilitated by high temperature, in conjunction with strong soil-stream hydrological connectivity, were important drivers for changes in the concentration and composition of stream water DOM. By comparison, watersheds with a high percentage of agricultural land use showed higher DOC concentration, larger proportion of soil-derived, humic-like DOM compounds, and higher DOC biodegradability. These observations reflect preferential mobilization of humic DOM compounds from shallow organic matter-rich soils in agricultural watersheds, likely due to enhanced soil erosion, organic matter oxidation and relatively shallow soil-to-stream flow paths.
Assuntos
Palavras-chave

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Compostos Orgânicos / Solo / Carbono / Rios / Agricultura País/Região como assunto: America do norte Idioma: En Ano de publicação: 2018 Tipo de documento: Article

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Compostos Orgânicos / Solo / Carbono / Rios / Agricultura País/Região como assunto: America do norte Idioma: En Ano de publicação: 2018 Tipo de documento: Article