Thursday, April 05, 2012, 4:30PM - 5:30PM
Recent increases in DOC concentrations in surface waters have been documented in northern temperate regions and the resulting impacts on aquatic ecosystems and drinking water quality is not fully understood. Disinfectants such as chlorine can react with natural organic matter (NOM), which is measured as dissolved organic carbon (DOC) concentration, in source waters to create disinfection byproducts (DBPs), some of which are known carcinogens. In Colorado, changes in DOC concentrations in the future may be driven by increasing growth of algae, a large source of DOC, due to a longer period of ice-free conditions on lakes and reservoirs under a changing climate and increasing nutrient inputs from atmospheric deposition and other anthropogenic sources.
These changes may present challenges to ensure safe drinking water as a result of increased DOC in Colorado. In the summer of 2010, the Colorado Department of Public Health and Environment (CDPHE) conducted a High Quality Water Supply study to assess the impact of algal growth in Colorado lakes and reservoirs on DOC concentrations and the potential to form DBPs. Twenty-eight lakes were sampled during July and August, at the peak of summer stratification, and 10 other drinking water reservoirs were sampled biweekly from May through September 2010. Chlorophyll-a, an indicator of algal biomass, was used to assess the relationship between algal concentrations and DOC concentrations. During the field sampling, additional surface samples were taken and preserved with Lugol’s, an iodine based solution, for phytoplankton identification and enumeration with a Fluid Imaging Technologies FlowCAM®. Funding from the Colorado Water Research Institute supported the development of a protocol to analyze the phytoplankton samples.
The results from the analysis of the phytoplankton using the FlowCAM® are being analyzed to understand the statistical relationships between the phytoplankton species, chlorophyll-a, nutrient levels, physical characteristics of the lake, and DOC concentrations. These results will be the basis of a MS Thesis in the Environmental Studies Department at University of Colorado – Boulder.