Land Use Impacts on the Development of Cyanotoxins and Taste-and-Odor Compounds in Benthic Algae Mats
Abstract
Cyanobacteria can grow in lotic and lentic environments and have been found to release a variety of chemicals, ranging from taste-and-odor compounds to harmful cyanotoxins. Taste-and-odor compounds make the public skeptical of safe drinking water and are expensive to treat. Cyanotoxins cause liver and nerve damage and have been linked with livestock and pet deaths. Benthic algae, or algae mats, are less understood compared to their planktonic counterparts and the variables that promote the production and release of cyanotoxins are not well understood. With this study, we investigate how urbanization of stream ecosystems impacts the abundance of cyanobacteria-dominated mats and the rate of toxin (microcystin, anatoxin-a, and saxitoxin) and nuisance compound (geosmin and MIB) production. Our study site includes three streams of Johnson County, Kansas, which are similar in climatic and geomorphologic characteristics apart from land use: Indian Creek (89% urban), Mill Creek (62%), and Blue River (21%). During summer 2021, we collected weekly samples of natural benthic substrates from each basin and used a handheld fluorometric probe (BenthoTorch) to estimate biomass and community composition. We also collected nutrient, organic matter, turbidity, temperature, velocity, and oxygen data. In the laboratory, we analyzed toxin concentrations using enzyme-linked immunosorbent assays (ELISA) and nuisance compound concentration using a gas chromatography-mass spectrometer (GC-MS). Preliminary results show the presence of taste and odor-compounds in over 80% of collected samples, with mean geosmin and MIB concentrations of 20.0±15.1 and 9.4±5.5 ng/L, respectively, exceeding suggested threshold of 5.0 ng/L. Microcystin was present in most samples and averaged 2.8±4.8 µg/L, below the advisory threshold for adults of 8.0 µg/L. Anatoxin-a and saxitoxin were less commonly observed and typically not in high concentrations. Interestingly, the most-urban stream had the greatest cyanotoxin concentrations while the most-rural stream had the greatest taste-and-odor levels; however, further work is required to assess the drivers of these differences. Understanding urbanizations impact on cyanotoxins will lead to the development of mitigation techniques and technologies that can help guarantee water quality.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H35Z..15R