Linked Life Data

18213973

Source:http://linkedlifedata.com/resource/pubmed/id/18213973

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
2008-1-24
pubmed:abstractText
Many studies have shown that intensive agricultural practices significantly increase the nitrogen concentration of stream surface waters, but it remains difficult to identify, quantify, and differentiate between terrestrial and in-stream sources or sinks of nitrogen, and rates of transformation. In this study we used the delta15N-NO3 signature in a watershed dominated by agriculture as an integrating marker to trace (1) the effects of the land cover and agricultural practices on stream-water N concentration in the upstream area of the hydrographic network, (2) influence of the in-stream processes on the NO3-N loads at the reach scale (100 m and 1000 m long), and (3) changes in delta15N-NO3 signature with increasing stream order (from first to third order). This study suggests that land cover and fertilization practices were the major determinants of delta15N-NO3 signature in first-order streams. NO3-N loads and delta15N-NO3 signature increased with fertilization intensity. Small changes in delta15N-NO3 signature and minor inputs of groundwater were observed along both types of reaches, suggesting the NO3-N load was slightly influenced by in-stream processes. The variability of NO3-N concentrations and delta15N signature decreased with increasing stream order, and the delta15N signature was positively correlated with watershed areas devoted to crops, supporting a dominant effect of agriculture compared to the effect of in-stream N processing. Consequently, land cover and fertilization practices are integrated in the natural isotopic signal at the third-order stream scale. The GIS analysis of the land cover coupled with natural-abundance isotope signature (delta15N) represents a potential tool to evaluate the effects of agricultural practices in rural catchments and the consequences of future changes in management policies at the regional scale.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
1051-0761
pubmed:author
pubmed:issnType
Print
pubmed:volume
17
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2333-46
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
15N-Nitrate signature in low-order streams: effects of land cover and agricultural practices.
pubmed:affiliation
ECOBIO-Unité Mixte de Recherche, 6553 CNRS, Institut Fédératif de Recherche CAREN, Université de Rennes I, Campus de Beaulieu, 35042 Rennes, France.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't