Presentation - National Water Research Institute

Day-time production and (initial) night-time dark loss rates
averaged 16±3 nMh -1 and 12±4 nMh -1 respectively.
Apparent quantum yields ranged from 0.04 to 0.09, with
average of 0.07 ± 0.02, similar to quantum yields of 0.09 ±
0.04 from lab studies
Production largely dominated by sunlight, with some
dependence CDOM levels in waters with highest abs.
Evidence for dark biological production?
› Between midnight and sunrise, net peroxide decay rate appears
to slow and peroxide levels remain constant well above the
detection limits of the instrument
› If observed initial night-time decay rate remains constant and
constant levels measured during midnight to sunrise period are
due to balance between measured night-time decay and dark
production process, estimated maximum dark production rates
range from 10.0 to 21.3 nM h -1 .