Biodegradation of phenol and catechol in cloud water: Comparison to chemical oxidation in the atmospheric multiphase system

Abstract

<p><strong>Abstract.</strong> The sinks of hydrocarbons in the atmosphere are usually described by oxidation reactions in the gas and aqueous (cloud) phases. Previous lab studies suggest that in addition to chemical processes, biodegradation by bacteria might also contribute to the loss of organics in clouds; however, due to the lack of comprehensive data sets on such biodegradation processes, they are not commonly included in atmospheric models. In the current study, we measured the biodegradation rates of phenol and catechol, which are known pollutants, by one of the most active strains selected during our previous screening in clouds (<i>Rhodococcus enclensis</i>). For catechol, biodegradation transformation is about ten times faster than for phenol. The experimentally derived biodegradation rates are included in a multiphase box model to compare the chemical loss rates of phenol and catechol in both the gas and aqueous phases to their biodegradation rate in the aqueous phase under atmospheric conditions. Model results show that the degradation rates in the aqueous phase by chemical and biological processes for both compounds are similar to each other. During daytime, biodegradation of catechol is even predicted to exceed the chemical activity in the aqueous phase and to represent a significant sink (17 %) of total catechol in the atmospheric multiphase system. In general, our results suggest that atmospheric multiphase models may be incomplete for highly soluble organics as biodegradation may represent an unrecognized efficient loss of such organics in cloud water.</p>

Biodegradation by bacteria in clouds: An underestimated sink for some organics in the atmospheric multiphase system

“…(5) (Jaber et al, 2020). Several experiments showed that temperature only had a small influence on the biodegradation rates that differed at most by a factor of 2 in experiments at 5°C or 17°C (Husárová et al,155 2011) (Vaïtilingom et al, 2010(Vaïtilingom et al, , 2011.…”

“…The metabolic activity of bacterial strains identified in cloud water (e.g. Pseudomonas, Sphingomonas) has been investigated in lab studies, and it was shown that they can biodegrade organics (e.g., malonate, succinate, adipate, pimelate, formaldehyde, methanol, acetate, formate, phenol and catechol (Delort et al, 2010) (Vaïtilingom et al, 2010(Vaïtilingom et al, , 2011(Vaïtilingom et al, , 2013 (Amato et al, 2007a) (Ariya et al, 2002) (Husárová et al, 2011) (Fankhauser et al, 2019) (Jaber et al, 2020). Based on comparisons of experimentally derived 60 biodegradation rates to chemical rates of oxidation reactions by radicals (e.g., OH, NO3) in the aqueous phase, it was concluded that they might be similar under some conditions, and that, depending on the abundance and metabolic activity of bacteria strains, oxidation and biodegradation processes of organics may compete in clouds.…”

Biotic and abiotic transformation of amino acids in cloud water: Experimental studies and atmospheric implications

“…CC BY 4.0 License. Jaber et al (2020). This concentration is at the upper limit of  OH concentrations in cloud water as derived from various model studies (Arakaki et al, 2013;Lallement et al, 2018).…”

“…A complementary experiment was also performed consisting of incubation of this solution in the presence of light without Fe(EDDS) complex. The experimental conditions of the irradiation experiments (Sylvania Reptistar lamps; 15 W; 6500 K) and the mechanism of the • OH radical production under light irradiation are described by Jaber et al (2020). 30…”

“…Another missing aspect concerns the potential biotransformation of these AAs in atmospheric waters. The microbial community which is present in cloud waters is metabolically active (Amato et al, 2017(Amato et al, , 2019Vaïtilingom et al, 2012) and has been shown the biotransform mono and dicarboxylic acids, methanol, formaldehyde, phenol and catechol (Ariya et al, 2002;Husárová et al, 2011;Jaber et al, 2020;Vaïtilingom et al, 2010Vaïtilingom et al, , 2011Vaïtilingom et al, , 2013. It is well-known 30 that microorganisms have enzymatic networks able to biodegrade or biosynthesize amino acids.…”