Table 1.
Solar radiation exposure (dose) for each experiment at four wavelengths (305, 320, 340, 380 nm) and the equivalent exposure days for the most biologically effective wavelength of 320 nm
| Experiment | Date | Dose (kJ/m2) |
No. of 320-nm exposure daysa | |||
|---|---|---|---|---|---|---|
| 305 nm | 320 nm | 340 nm | 380 nm | |||
| A: Oocysts on top and bottom of biofilm | July 9 | 0.7 | 4.0 | 8.6 | 10.4 | 0.37 |
| B: Biofilm-associated oocysts resuspended in creek water | July 15 | 0.5 | 3.1 | 6.6 | 8.3 | 0.28 |
| C: Oocysts on top and bottom of biofilm and resuspended biofilm-associated oocysts | August 25 | 0.3 | 2.5 | 5.5 | 6.9 | 0.23 |
a
A value of 10.9 kJ/m2 represents one 320-nm exposure day or the amount of solar UV at 320 nm received during 1 day of full sunlight (no clouds) at the water surface during summer solstice and average ozone conditions at 41°N latitude (7).