1. Controls on Catchment-Scale Patterns of Phosphorous in Soil, Streambed Sediment, and Stream Water Marcel van der Perk, et al… Journal of Environmental Quality, 2007

2. Presentation Outline 1)Overview 2)Methods 3)Results 4)Conclusion 5)Discussion/Critique

3. 1. OVERVIEW

4. Goal of Research: Attempt to quantify the unique and joint contribution of… 1)Soil type, soil chemical properties, and land use 2)Soil [P], sediment chemical properties, and point source emissions 3)Sediment chemical properties, water chemistry, and point source emissions Spatial variation of [P] in soil Spatial variation of [P] in streambed sediments Spatial variation of [P] in stream water Independent variablesDependent variables

5. 1. OVERVIEW Motivation for the goal: Phosphorous is a common limiting nutrient in both aquatic and terrestrial ecosystems Scientists know it is controlled by climate, geology, topography, and anthropogenic influences Yet to be successfully quantified/modeled at basin scale Valid models can be very useful Geochemical dataset available in the watershed promised possibility of “breaking new ground”

6. 1. OVERVIEW The Watershed Southwest England 976 km 2 (377 mi 2 ) 72% grassland 6% farmable 17% forest 50 STW, mostly small dispersed towns

7. 2. METHODS

8. Geochemical survey (2002) 460-495 samples of each of the major top soil type, Stream water, & streambed sediment Soil-> randomly within every 2 nd square kilometer (systematic random) Streambed-> 1 st to 4 th order streams (systematic) Stream water-> same locations as streambed

9. 2. METHODS Spatial Data Also made interpolated maps from geochemical survey (conditional simulation) *******all data re-sampled to 25m resolution

10. 2. METHODS Statistical Analysis Ln transformed if regression residuals not normally distributed Only considered variables in regressions if significant (α=0.05, ANOVA) Multiple linear regression coefficient must be logical Coefficient of Determination (R 2 ) used to partition variation

11. 2. METHODS Partitioning the Variance

12. 2. METHODS Partitioning the Variance

13. 3. RESULTS

14. Soil Data

15. 3. RESULTS Soil Data

16. 3. RESULTS Result of conditional simulation interpolation Soil Data

17. 3. RESULTS Streambed Data

18. 3. RESULTS Streambed Data

19. 3. RESULTS Stream Water

20. 3. RESULTS Stream Water

21. 4. CONCLUSION

22. 1.Soil Parent Material is major factor controlling catchment-scale spatial variation in soil TP and Olsen P, land cover is important too 2.Streambed [P] are correlated with major elements (adsorption). 3.Streambed [P] better predicted by erosion model and land use than upstream soil tests 4.Illustrates complex cascade of P transfer from soil to streambed to stream water under baseflow conditions (long term accumulation/diff sized storms) 5.Problems with spatial data

23. 5. DISCUSSION/CRITIQUE

24. 1.Cluster analysis? 2.GIS techniques 3.Erosion model