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Center for Earth and Environmental
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2008
Research Program Cyanobacterial Ecology and Toxicology of Central Indiana Reservoirs Given the ecological, recreational, and municipal uses of Eagle Creek, Geist and Morse Reservoirs, maintaining and improving their water quality has been a focus of the Central Indiana Water Resource Partnership (CIWRP). In 2007, microcystin, an algal toxin, was discovered in Geist Reservoir at very low levels. In response to these reports and in an effort to understand the potential risks associated with cyanoabacterial blooms for the production of toxins, in addition to the continued problems associated with their production of taste and odor compounds, CIWRP undertook a detailed study of the three reservoirs, This study is a comprehensive study of the phytoplankton ecology of the three reservoirs and for the first time documented the occurrence of taste and odor compounds (MIB and geosmin) as well as cyanotoxins. An additional component of this project is the development of a microcystin ELISA laboratory at IUPUI. Research continues into determining the effectiveness of this approach for rapid screening in central Indiana reservoirs. The study has three main purposes: 1) To document algal community composition and abundance; 2) To determine the relationship between physical and chemical reservoir conditions and algal community structure and abundance; 3) To document the occurrence of cyanobacterial toxins and taste and odor compounds Results of the 2008 study are providing important information regarding differences and similarities of phytoplankton community structure and the occurrence of cyanotoxins and taste and odor metabolites in the three reservoirs. Information from this work has been presented at an international lake conference and this work is contributing to a very limited data set for the Midwestern US, despite the fact that known toxin producing genera comprise dominant components of cyanobacterial populations in the three reservoirs as well as numerous lakes and reservoirs in the region. Research has documented the key toxin and taste and odor producing species as well as documented that two of the three priority cyanotoxins identified by USEPA were not present in central Indiana reservoirs in 2008. Further, the 2008 study showed that microcystins occur in central Indiana reservoirs but at very low levels in comparison to other reported levels throughout the United States, Given the importance of the central Indiana reservoirs for the drinking water supply and the potential for significant differences in annual variability in cyanobacterial populations, weather, and watershed/reservoir linkages, the study will be extened for a second year in 2009. Mapping Blue-Green Algae with Hyperspectral Remote Sensing in Central Indiana Reservoirs Nuisance blue-green algal blooms occur seasonally in the Indianapolis drinking water reservoirs. These blooms can lead to aesthetic degradation, taste and odor in finished drinking water, and can potentially produce toxins. Current methods for detecting blooms are costly and time consuming, delaying management decisions. Remote sensing techniques which utilize the optical properties of blue-green algal pigments (chlorophyll a and phycocyanin) can provide rapid detection of blue-green algal distribution. In 2005, CIWRP and the Lake and River Enhancement Program of the Indiana Department of Natural Resources funded a research project to develop an assessment tool to map nuisance blue-green algal blooms in Central Indiana reservoirs. Using the optical properties of phytoplankton pigments such as chlorophyll a and phycocyanin, a pigment unique to blue-green algae, CEES researchers were able to develop methods to rapidly map blue-green algae using light reflectance data. Reflectance data collected both by boat-based and airplane-based sensors on Eagle Creek, Geist, and Morse Reservoirs have resulted in maps of blue-green algae distribution in all three reservoirs. In 2006 and 2007, CIWRP funding has allowed for continued efforts to refine and improve the accuracy of developed remote sensing algorithms. This assessment tool has been effective as a real-time tool for tracking the distribution of blue-green algae in the reservoirs, has been successfully used to guide algaecide applications and has resulted in better understanding of algal blooms. In 2007, research worked to refine algorithms by determining the reservoir conditions that lead to error in the predictive algorithms and develop models to improve accuracy. In-situ field reflectance spectra were collected from June to November 2006 over a wide range of bloom conditions using ASD Fieldspec (UV/VNIR) and Ocean Optics USB2000 (V/NIR) spectroradiometers. Ground truth samples were analyzed for Chlorophyll a, phycocyanin, total suspended sediment, and other water quality constituents. In-vitro chlorophyll a and phycocyanin concentrations were measured flourometrically. Previously published spectral algorithms for the detection of phycocyanin were evaluated against analytically measured pigment concentrations. Results indicate that algorithm predictions provide accurate estimations of pigment concentration and distributions. Algorithm accuracy is affected by multiple water constituents, particularly turbidity. Partial least squares models modified to correct for turbidity affects can improve prediction power (R2 values from 0.70 – 0.90). This research continues to explore enhanced algorithm development and modification. This work has been successfully utilized to guide sampling for bloom characteristics and target algaecide applications. In 2008, we will extend testing to satellite-based sensors and continue work to enhance prediction accuracies and transferability to algorithms via bio-optical modeling techniques. Nutrient Specific Flow Paths during Storm Events in a Glaciated, Artificially Drained Landscape This study investigated nitrate and dissolved organic carbon (DOC) export during three spring storm events in an agricultural watershed and a mixed agricultural/urban land use watershed in a till landscape in Central Indiana (Schoolbranch and Eagle Creek). The objectives of the study are (1) to determine how land use affects water, nitrate, and DOC delivery (timing, amount) to streams during spring storms, and (2) to determine nitrate and DOC flow pathways to streams during storms. High frequency stream sampling of nutrients and cations, coupled with hydrograph separations using δ18O, were used to identify water flow pathways and event and pre-event water contributions to the streams. Results indicate that nitrate and DOC concentrations display distinct temporal patterns during spring storm events. DOC concentration increased with stormflow, and peaked with discharge and the peak in event water regardless of land use or storm characteristics. Nitrate concentrations followed Ca2+, Mg2+, and Na+ trajectories and decreased with stormflow in both watersheds. In addition, the nitrate concentration peak was delayed relative to DOC in the mixed land use watershed. Data suggest that during storms, DOC is exported either via overland flow or via preferential flow through soil macropores. On the other hand, nitrate appears to be mainly delivered to streams in association with pre-event water via subsurface flow. This study contributes to a better understanding of nutrient export pathways during storms for a variety of land uses and to the development of better management strategies and nutrient loading models at the watershed scale. It has aided our understanding of both where and when nutrients are being exported into streams in both agricultural and developing areas of the local watersheds and helping guide nutrient management decisions to improve water quality. 3D Hydrologic Model of Eagle Creek Reservoir The objectives of this project are to a) develop a 3D hydraulic model of the Eagle Creek Reservoir to understand the hydrodynamic behavior of the reservoir, and b) design and undertake a monitoring campaign to validate the hydraulic model during different hydrologic conditions (e.g. high watershed discharge, high wind events without watershed discharge, low flow and stagnant conditions). The development of a 3D hydraulic model for Eagle Creek Reservoir fills a critical gap in the understanding of reservoir flow dynamics and will provide important information to better enable researchers and managers to investigate the relationships between the hydraulics of the reservoir and the development of blue green algae blooms. Reservoir hydraulic models will be combined with nutrient mass balance information and watershed loading data to better help identify conditions conducive to the onset of algal blooms. Hydraulic model information will also used to help manage Eagle Creek Reservoir water usage and algal bloom treatment. |
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