The effects of fluoride based fire-fighting foams on soil microbiota activity and plant growth during natural attenuation of perfluorinated compounds

Abstract

The use of fluoride based foams increases the effectiveness of fire-fighting operations, but they are also accompanied by major drawbacks regarding environmental safety of perfluorinated compounds (PFCs). The main concern with PFCs release is due to their well-known persistence and bioaccumulative potential, as they have been detected in many environmental samples. There is a significant knowledge gap on PFC toxicity to plants, even though such data could be useful towards bioremediation procedures. It is consensus that a realistic assessment of fire-fighting foam toxicity should cover as many test organisms as possible, however, few studies combine the performance of ecotoxicological tests with a detailed study of microbial communities in soil contaminated with firefighting foams. Our research evaluated the effects of natural attenuation of PFCs on the development of arugula and lettuce seeds. The effects of variable PFCs amounts were also observed in soil microbiota using the 2,6 dichlorophenol-indophenol redox dye as microbial metabolism indicator. We aimed to determine whether aqueous film forming foams toxicity increased or decreased over time in a simulated contamination scenario. We argued that the long-term biotransformation of fire-fighting foams should be taken in to account when evaluating toxicity, focusing on a time-based monitoring analysis, since potentially toxic intermediates may be formed though biodegradation. The phyto-toxicity of PFCs to lettuce and arugula was high, increasing as a function of the concentration and decreasing as a function of exposure time to the environment. However, very specific concentrations throughout biodegradation result in the formation of non-inhibiting intermediates. Therefore, variable biodegradation-dependent germination rates may be misleading on non-time-based monitoring approaches. Also, the low phyto-toxicity after 240days does not exclude the potential for PFC bioaccumulation in plants. We also proposed that the colorimetric data modelling could also establish a novel toxicity parameter to evaluate the release impacts to soil and biota. The combined assays allowed the monitoring of PFCs during long-term exposition to plants as well as their immediate effects on the same soil microbiota.

Effect of Fluoride on Germination, Early Growth and Antioxidant Enzymes Activity of Three Winter Wheat (Triticum aestivum L.) Cultivars

“…When the seeds initiate growth, they need appropriate internal and environmental conditions. However, changes in these conditions caused by toxic substances such as NaF result in changes in the seed's metabolism [32][33][34]. The high levels of fluoride lead to the production and accumulation of ROS, as well as changes in the enzymatic antioxidant system.…”

Chemometrics-Assisted Monitoring in Raman Spectroscopy for the Biodegradation Process of an Aqueous Polyfluoroalkyl Ether from a Fire-Fighting foam in an Environmental Matrix

“…Water and/or soils pollution are extensively discussed in the literature, as well as the biodegradation of anthropogenic pollutants and their effects on the environment. In the specific case of fluorinated aliphatic molecules present as surfactants in many industrial contexts [1], the bibliography is limited for surfactants used as fire-fighting foams [2][3][4][5][6][7][8][9]. These chemical compounds are considered as toxic [10,11].…”

Fluoride contributes to the shaping of microbial community in high fluoride groundwater in Qiji County, Yuncheng City, China

“…Fluoride is a toxic element that can cause fluorosis to organisms 1,2 whether excessive or deficient. Recently, it has also been identified as a fundamental factor impacting microbial activity and communities in environment 3,4 due to its potential antimicrobial activity 5,6 . One piece of evidence for the antimicrobial activity is the anticaries actions of fluoride by affecting bacterial metabolism 7 .…”

“…Additionally, numerous studies have reported on the ability of fluoride, normally as sodium fluoride, to cause changes to microbial activity and community composition in soil 4,12 . Fluoride-induced changes of chemical properties and microbial activities in humus soils were reported by Wilke 13 ; it was shown that dehydrogenase, alkaline phosphatase and arylsulfatase activities as well as nitrification were inhibited at much lower F-additions in the moder and mor soils.…”