A platform for research: civil engineering, architecture and urbanism
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Nitrogen stable isotopes in streams: effects of agricultural sources and transformations
The nitrogen stable isotope ratio of biological tissue has been proposed as an indicator of anthropogenic N inputs to aquatic ecosystems, but overlap in the isotopic signatures of various N sources and transformations make definitive attribution of processes difficult. We collected primary consumer invertebrates from streams in agricultural settings in Wisconsin, USA, to evaluate the relative influence of animal manure, inorganic fertilizer, and denitrification on biotic δ15N. Variance in biotic δ15N was explained by inorganic fertilizer inputs and the percentage of wetland land cover in the watershed, but not by animal manure inputs. These results suggest that denitrification of inorganic fertilizer is the primary driver of δ15N variability among the study sites. Comparison with previously collected stream water NO3‐N concentrations at the same sites supports the role of denitrification; for a given N application rate, streams with high biotic δ15N had low NO3‐N concentrations. The lack of a manure signal in biotic δ15N may be due its high ammonia content, which can be dispersed outside the range of its application by volatilization. Based on our findings and on agricultural census data for the entire United States, inorganic fertilizer is more likely than manure to drive variability in biotic δ15N and to cause excessive nitrogen concentrations in streams.
Nitrogen stable isotopes in streams: effects of agricultural sources and transformations
The nitrogen stable isotope ratio of biological tissue has been proposed as an indicator of anthropogenic N inputs to aquatic ecosystems, but overlap in the isotopic signatures of various N sources and transformations make definitive attribution of processes difficult. We collected primary consumer invertebrates from streams in agricultural settings in Wisconsin, USA, to evaluate the relative influence of animal manure, inorganic fertilizer, and denitrification on biotic δ15N. Variance in biotic δ15N was explained by inorganic fertilizer inputs and the percentage of wetland land cover in the watershed, but not by animal manure inputs. These results suggest that denitrification of inorganic fertilizer is the primary driver of δ15N variability among the study sites. Comparison with previously collected stream water NO3‐N concentrations at the same sites supports the role of denitrification; for a given N application rate, streams with high biotic δ15N had low NO3‐N concentrations. The lack of a manure signal in biotic δ15N may be due its high ammonia content, which can be dispersed outside the range of its application by volatilization. Based on our findings and on agricultural census data for the entire United States, inorganic fertilizer is more likely than manure to drive variability in biotic δ15N and to cause excessive nitrogen concentrations in streams.
Nitrogen stable isotopes in streams: effects of agricultural sources and transformations
Diebel, Matthew W. (author) / Zanden, M. Jake Vander (author)
Ecological Applications ; 19 ; 1127-1134
2009-07-01
8 pages
Article (Journal)
Electronic Resource
English
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