1. Transport of nitrogen and phosphorus from Rhode River watersheds during storm events David Correll, Thomas Jordan, and Donald Weller Water Resources Research, 1999. Vol. 35 No 8 pg 2513-2521

2. Why this paper? One of many papers from the SERC on the Rhode River Watershed since the 1970s Effects of land use, season, and storm characteristics on nutrient transport

3. Land Use effects: 4 watersheds Watershed 101 Mixed Use Land Use Watershed 109 Crops Watershed 110 Forest Watershed 111 Grazed Forest Row crops Pasture and Hay fields Residential Old Fields Site Description

5. Chemistry Phosphorus –PPi, Dpi, POP, DOP Nitrogen –NO3-, NH4, PON, DON –Continuous baseflow samples and storm samples –Collected and returned w/in 24 hr –Filtered 0.45  m

6. Discharge 120° and 150 ° V notch weirs Stilling wells, floats every 5 minutes

7. Steps: 1.Connect the concentrations using a linear interpolation 2.Integrate the instantaneous load for the period between the first sample and the last using equation (1) (1) Loads: Linear interpolation

8. Base flow vs. Storm Storm Particulate + Dissolved Fractions added

9. Characteristic Storms (WS 101)

10. P and N Dynamics June storm (WS 101) P N

11. Storm P & N Dynamics (all 4) P N

12. Seasonal P Comparison WS 101: Mixed LU WS 109: Cropland LU

13. Seasonal N Comparison WS 101: Mixed LUWS 109: Cropland LU Summer: Particulates

14. P c-Q relationships

15. N/P Relationships Mainly due to increases in Particulate P

16. Discussion Particulate nutrients related to soil, soil erosion.

17. Discussion Peak water discharge correlated to mean particulate nutrient concentrations –Eliminating need to know rainfall volume or intensity –Smaller 1 st order catchments –Shorter, more intense storm discharges [NH4] increased with peak water discharge - slopes much lower

18. Discussion Sampling implications 1 large summer storm –24% of TP for entire summer –18% of TPi for entire summer –30% of TOP for entire spring –18.5% of TON for entire spring 1 large spring storm –39% of TP for entire spring –41% of TPi for entire spring –38% of TOP for entire spring –12% of of TON for entire spring

19. Questions????? Why do storms increase particulate nutrient concentrations but do not influence dissolved concentrations? If sediment related, why isn’t rain (detachment) as important as flow? Implications for sampling: every storm? Or use different load estimation? Internal validity- are differences really seasonal and land use related External validity? – how is this applicable to other watersheds