Toxicity of perfluorinated compounds to soil microbial activity: Effect of carbon chain length, functional group and soil properties

Perfluorinated compounds (PFCs) have been detected at various concentrations in different environment compartments due to their widespread usage. Nowadays, soil environment has become a prominent sink of PFCs from surface runoff and penetration, but few researches have been conducted in the toxicity of PFCs to soil microorganisms. To address the issue, microcalorimetry was applied to investigate the toxicity of six PFCs with different carbon chain length (4, 8, and 10) and functional group (carboxylic and sulfonic) to microbial activities in three Chinese soils varying widely in soil properties. Adsorption of PFCs by soil matrix was a key factor in controlling the toxicity of PFCs to soil microorganisms. The differences of carbon chain length and functional groups of PFCs have different impacts on soil microbial activity while affecting adsorption progress. Particularly, the sulfonic PFCs expressed higher toxicity than the carboxylic. It is also identified that the longer the chain length, the greater the toxicity of PFCs. Soil pH was another relevant factor of soil adsorption, and with the increase of pH, adsorption capability increased. Soil available P, N and K were essential nutrients in soil, and suggested to improve microbial activity under PFCs stress.