To better define the spatial and temporal variability of H2O2 in waters of the three basins of Lake Erie.
To assess the role of superoxide, O2-, the precursor of H2O2, in the fate and transport of organic pollutants in Lake Erie.
To determine the steady state concentrations of singlet oxygen, 1O2, in Lake Erie.
To assess the relative importance of these two photochemically produced reactive species in the fate and transport of organic pollutants in Lake Erie.
To assess the potential of using H2O2 as a chemical tracer for physical (mixing) processes.

Reactive intermediates which are formed photochemically in surface waters may have a profound effect on redox processes, pollutant transport and fate, and biological processes. Hydrogen peroxide is one of the more stable secondary products formed in situ as a result of these photochemical processes. The precursor of H₂O₂ is thought to be superoxide, O₂-. Superoxide is known to have adverse effects on biological processes and may also react directly with pollutants.

A project involving both laboratory and field studies is proposed. Field studies will involve the three major basins of Lake Erie, and be conducted on the CSS LIMNOS. The rate of formation and decay of H2O2 will be determined in situ and in samples after filtration through different pore size filters. These studies will be aimed at determining the processes responsible for both formation and decay. Experiments with selected pollutants will also be conducted, in the presence and absence of natural humic substances from Lake Erie.

1990: A project involving both laboratory and field studies has been proposed, the field studies involve the three major basins of Lake Erie, and are being conducted on the CSS LIMNOS. Methodology to examine the photochemical formation of H2O2 at various depths in at least one basin and to determine the major processes involved in the decomposition of H2O2 is being used. Experiments with selected pollutants will also be conducted, in the presence and absence of natural humic substances from Lake Erie.

Accomplishments:
We have described the spatial and temporal variability of H₂O₂ in the three basins of Lake Erie. This study will be extended to determine areal ???diel variability in Summer 1990.RESULTS: We have described the areal distribution of H₂O₂ in the three basins of Lake Erie. From these calculations, we have concluded that the total amount of H₂O₂ that is formed is very similar in all areas and that mixing plays a major role in determining the distribution of H₂O₂ in the water column.

We have determined the noon-time steady state concentrations of singlet oxygen in several lakes including Lake Erie Station 23 (Eastern Basin) and Station 357 (Western Basin). Singlet oxygen quantum yields at different wavelengths are also being determined for one Lake Erie water (Station 23). Singlet oxygen may be important in the fate and transport of organic pollutants in the lake.

Benefits:
The results to date are the first to be published on any major lake.