False-Positive Error by Microparticles in Solid Phase Bioluminescence Inhibition Test and Its Correction for Predicting

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False-Positive Error by Microparticles in Solid Phase Bioluminescence Inhibition Test and Its Correction for Predicting Soil Toxicity from Soil Solution Toxicity Jinsung An

Received: 13 June 2020 / Accepted: 26 October 2020 # Springer Nature Switzerland AG 2020

Abstract In this study, light intensities of Aliivibrio fischeri obtained from soil suspension and its filtrate were compared using field soils contaminated with heavy metals. The soils collected from rice paddy and forest had different soil textures with either high or low silt/clay content. The correlation between soil toxicity and soil solution toxicity for A. fischeri showed a high linearity in sandy soils with the slope of 0.586 (determination coefficient; R2 = 0.709). Meanwhile, a lower correlation in silty/clay soils with the slope of 0.154 (R2 = 0.067) was observed. When a solid phase bioluminescence inhibition test is carried out using soil suspension with a high silt/ clay content, a large amount of A. fischeri seems to adhere to microparticles and/or microaggregates. It may result in the change of light intensity (i.e., distorted toxicity test result) that could not be corrected by the modified basic solid phase test protocol, and thus the toxicity is likely to be overestimated. Such alteration in the light Highlights • The correlation between soil toxicity and soil solution toxicity for A. fischeri was investigated using heavy metal-contaminated soils. • A high linearity in the correlation in sandy soils and a lower linearity in silty/clay soils were observed. • It may result from the microbial loss by adhesion to microparticles that could not be corrected by mBSPT protocol. • With the correction for microbial adhesion by a regression equation, the correlation increased from 0.182 to 0.571 in silty/ clay soils. J. An (*) Department of Biological & Environmental Engineering, Semyung University, 65 Semyung-ro, Jecheon-si, Chungcheongbuk-do 27136, Republic of Korea e-mail: [email protected]

intensity could be partially overcome using a regression equation accounting for microbial loss by adhesion. With the correction for microbial adhesion, the correlation between soil toxicity and soil solution toxicity in the selected soil samples with high silt/clay contents increased from 0.182 (R2 = 0.130) to 0.571 (R2 = 0.602). It is expected that soil toxicity can be evaluated through the prediction of soil solution toxicity after the proper correction of microparticles effects. Keywords Bioluminescence inhibition test . Aliivibrio fischeri . Soil toxicity . Soil solution toxicity . Falsepositive error

1 Introduction The total concentration of heavy metals in soil cannot always be used as an effective indicator of bioavailability or toxicity, because many heavy metals in soils do not affect living organisms owing to various factors such as pollution history and the physicochemical properties of soils (An et al. 2015; Lock and Janssen 2003; Vig et al. 2003). This indicates that the soils are not necessarily harmful even if the heavy metal concentration ex