Evaluating the Effects of Fire Retardants on a Natural Stream in an Active Wildfire Zone and the Survival Response of Selected Model Organisms, While Developing a Novel Method for the Bioremediation of Retardant-Damaged Streams

Overview

Wildfires are growing in both number and intensity across the United States as a result of many factors, including climate change, extreme drought, and human impacts. With this increase of wildfires comes the increased use of Ammonium-Polyphosphate based fire retardant to protect homes and property. However, the environmental effects and toxicity of these retardants remain highly unknown, in addition to an effective method of bioremediation for streams impacted by fire retardants. A field study was conducted on South Hardscrabble Creek in Junkins, Colorado, which was exposed to a wildfire with fire retardant drops three days before testing. When sites upstream from the retardant drops were compared to sites downstream from the retardant drops, it was observed that the fire retardants had a damaging effect on factors crucial to support a stream ecosystem: Dissolved Oxygen, pH, Nitrates, and Phosphates. Toxicity studies were conducted utilizing many different species in order to evaluate the effects of the retardants on different levels of the food chain in a stream ecosystem. E. coli and B. subtilis were observed in an MIC test and Biofilm growth test. Artemia franciscana and Crustacea amphipoda, exposed to different concentrations of Phos-Chek LC-95AF Fire Retardants, showed an extremely low survival rate in concentrations down to 0.03125% in one day. A Simulated Stream Flow System (SSFS) was designed and built to simulate the flow of a natural stream in the toxicity study utilizing Lymnae stagnalis as an indicator species. Within one day, organisms in the control had survived and begun the reproduction cycle, while species in 0.0625% concentration of fire retardant were unable to survive, indicating that retardant, even in an extremely diluted state, is damaging to life in a stream ecosystem. Therefore, a method of bioremediation is needed to aid in the recovery of damaged streams. Algae and cyanobacteria were used to accomplish this in the form of Sodium Alginate Beads. As the algae photosynthesizes, reintroducing dissolved oxygen into the stream. The cyanobacteria go through nitrification, breaking down the ammonium from the retardants, which is toxic to aquatic species at even small concentrations, into nitrates, which are valuable nutrients and promote stream growth. Finally, both the algae and cyanobacteria used the excess phosphates from the retardants as nutrients, preventing the stream from experiencing eutrophication. Therefore, this solution provides an effective and low-cost method for the remediation of streams affected by fire retardants.

Competition history

• AJAS 2018 Category not listed

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