CDOM: Current Studies
Our current CDOM research is supported by grants from the National Science Foundation (NSF) and Legislative-Citizen Commission on Minnesota Resources (LCCMR). The NSF grant is focused on three ecoregions that span northern regions of the Upper Great Lakes states: Minnesota, Wisconsin, and Michigan. It has four main objectives:
- Develop robust equations to retrieve CDOM data from satellite imagery and use the results to develop census-level data on CDOM levels for all lakes in three Upper Midwest ecoregions;
- Evaluate long-term trends in lake CDOM in northern Minnesota using ground-based data and historical Landsat imagery;
- Determine relationships between landscape properties, climate and CDOM distribution and characteristics; and
- Elucidate relationships between CDOM and DOM characteristics and effects on formation of disinfection byproducts during drinking water treatment.
A fifth objective – development of a smartphone CDOM app and promotion of its use in citizen science – is the focus of an NSF supplemental award to the main grant. This topic is covered on the CDOM app and Citizen Science page.
The LCCMR project extends satellite measurement of CDOM across the state of Minnesota and is coupled with similar mapping activities for chlorophyll and turbidity/suspended matter concentrations in the state’s lakes.
Our CDOM work thus involves many facets, and relationships that are illustrated below.
The geographic focus of the NSF project is shown in the map below and includes the Northern Lakes and Forest (NLF) ecoregion and the North Central Hardwood Forest (NCHF) ecoregion, both of which extend across the three-state region, as well as the Northern Minnesota Wetlands (NMW), in northern Minnesota. The map also delineates sampling locations during our extensive field work in 2016 to obtain calibration/validation data for satellite imagery.
We currently are finalizing a map of the distribution of CDOM in the study area based on satellite imagery from 2015 and 2016, and it will be uploaded to this page when it is completed. A preliminary version of a CDOM map for the entire state of Minnesota can be seen by clicking on 2015 Minnesota CDOM distribution.
We are finishing work on a manuscript describing the association of iron with CDOM and DOC in the study area. The manuscript addresses two important questions: (i) how important is iron is in affecting observed a440 values, and (ii) does the variability of dissolved iron in CDOM-rich waters affect the reliability of DOC estimates based on satellite or ground-measured CDOM levels? A summary of the paper’s findings will be posted here once the manuscript has been submitted. Finally, we also are in the process of analyzing the extensive ground-based data we collected across the study area in 2016 for relationships among the measured variables and spatial patterns in the data. A summary of these findings also will be posted here when the work is completed.