Investigation of triclosan contamination on microbial biomass and other soil health indicators

Abstract

Triclosan (TCS), is an antimicrobial compound found in personal care products, and consequently in greywater. After its release to the environment it continues its antimicrobial action on indigenous microbial communities. Little is known about the environmental impacts of high levels of TCS, which may occur due to accumulation following long term greywater application to soil. Soil microcosms were established using a silty clay loam and augmented with a range of triclosan concentrations ranging from 500 mg kg⁻¹ to 7500 mg kg⁻¹. Samples were analysed for substrate induced respiration, microbial biomass and sulphatase activity. The soil augmented with the the lowest concentration of TCS (500 mg kg⁻¹) significantly decreased microbial biomass, with a calculated EC₂₀ of 195 mg kg⁻¹. Substrate induced respiration indicated that the soil microbial community was impacted for all TCS concentrations, however the community showed potential to recover over time. Sulphatase activity was less sensitive to TCS and was significantly impacted at high concentrations of TCS (> 2500 mg kg⁻¹). It is likely that TCS has selective toxicity for more susceptible microbes when introduced into the soil environment. At high levels TCS could overwhelm TCS-degrading soil microbes.

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