Concentrations of nitrogen and phosphorus in streams draining the mixed land-use Dee Catchment, north-east Scotland
Article first published online: 4 JAN 2002
Journal of Applied Ecology
Volume 37, Issue Supplement s1, pages 159–170, September 2000
How to Cite
Edwards, A.C., Cook, Y., Smart, R. and Wade, A.J. (2000), Concentrations of nitrogen and phosphorus in streams draining the mixed land-use Dee Catchment, north-east Scotland. Journal of Applied Ecology, 37: 159–170. doi: 10.1046/j.1365-2664.2000.00500.x
- Issue published online: 25 JUN 2002
- Article first published online: 4 JAN 2002
- N : P ratio;
- nutrient enrichment;
- organic nitrogen;
1. There is still some uncertainty about large-scale influences on nutrient budgets in rivers. In particular, reduced forms of nitrogen (N) in organic forms might represent a significant fraction of the soluble N present in headwater streams, but this is not well quantified. Nitrate increases in relative importance downstream within agriculturally dominated areas. Here we appraise variations in N dynamics for a representative temperate but upland river, the Dee.
2. In the Dee catchment, the source of organic N appears to vary seasonally. During summer under low flow conditions it originates primarily from in-stream biological production, while during the winter–spring period leaching from the plant–soil system would be the major contributor.
3. On any individual sampling day, a wide range of N : P ratios can occur in the catchment area. Generally the narrowest N : P ratios occur during the summer and early autumn, particularly for upland catchments dominated by semi-natural vegetation. It is possible that some of the tributaries and upper region of the main river may be limited by N during the summer. The interpretation of the N : P ratios depends greatly upon the potential biological availability of the organic N, which remains unknown.
4. Together, these data further illustrate that simple ideas about the relative limiting effects of N and P in temperate freshwaters may be misleading.