transport of nitrogen and phosphorus from rhode river watersheds during storm events david correll,...
TRANSCRIPT
Transport of nitrogen and phosphorus from Rhode River watersheds during storm events
David Correll, Thomas Jordan, and Donald WellerWater Resources Research, 1999. Vol. 35 No 8 pg 2513-2521
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
Land Use effects: 4 watershedsWatershed 101 Mixed Use Land UseWatershed 109 CropsWatershed 110 ForestWatershed 111 Grazed
ForestRow cropsPasture and Hay fieldsResidentialOld Fields
Site Description
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 /1 2 /0 2 1 5 :3 0 6 /1 2 /0 2 1 7 :1 0 6 /1 2 /0 2 1 8 :4 9 6 /1 2 /0 2 2 0 :2 9 6 /1 2 /0 2 2 2 :0 90
0 .0 2
0 .0 4
0 .0 6
0 .0 8
0 .1D
isch
arge
(cm
s)
3 0
4 0
5 0
6 0C
oncentration (mg/l)
t
t
ii
o
QCL
Steps:1. Connect the concentrations using a linear
interpolation2. Integrate the instantaneous load for the period
between the first sample and the last using equation (1)
(1)
Loads: Linear interpolation
Discussion
Peak water discharge correlated to mean particulate nutrient concentrations– Eliminating need to know rainfall volume or intensity
– Smaller 1st order catchments
– Shorter, more intense storm discharges
[NH4] increased with peak water discharge- slopes much lower
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
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