Site Remediation in Northern Climates: Microbial Respiration Models for Petroleum Hydrocarbon- contaminated Soils at Low Temperatures

Jihun Kim, Wonjae Chang

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Geoenvironmental Engineering

ABSTRACT: Site remediation in cold regions, including remote northern sites, is challenging since surrounding environmental conditions are harsh and the summers for active treatment are short, which complicate logistics for remediation. Site remediation, monitoring and management strategies for cold contaminated sites must therefore be extremely efficient. Microbial respiration measured in biologically treated contaminated soils is a simple on-site soil indicator that provides useful information about microbial enhancement in laboratory and field studies. The overarching question addressed by this study is how existing microbial respiration equations explain the combined temperature and unfrozen water dependency of microbial respiration in petroleum hydrocarbon-contaminated northern soils. The Arrhenius equation-based respiration model presented previously accurately describes temperature-dependent microbial respiration. However, the temperature dependency alone cannot explain the observed seasonal activation of cold-adapted microorganisms active at sub-zero temperatures. In this study, a generalized soil respiration model (GRESP) that accounts for the combined effects of temperature and water content was modified and the seasonal activation (onset) of cold-adapted microorganisms in petroleum hydrocarbon-contaminated soils from a northern site was successfully demonstrated. RÉSUMÉ L'assainissement des sites contaminés dans les régions nordiques ayant un climat froid est particulièrement difficile car les conditions environnementales sont sévères et les périodes de traitement en été sont courtes, ce qui complique la logistique de l'assainissement. En plus, ces sites sont souvent inaccessibles. Les stratégies d'assainissement employés dans les régions nordiques doivent donc être extrêmement efficaces. La respiration microbienne mesurée dans les sols contaminés qui sont biologiquement traités est un simple indicateur utilisé fréquemment dans les études en laboratoire et sur le terrain qui fournit des informations utiles sur l'amélioration de la performance des micro-organismes à la suite d'un traitement. La grande question abordée par cette étude est comment les équations existantes formulées pour décrire la respiration microbienne expliquent-elles les effets combinés de la température et la quantité d'eau liquide sur la respiration microbienne dans les sols contaminés par des hydrocarbures pétroliers. Le modèle de respiration bactérienne déjà développé qui est basé sur l'équation d'Arrhenius décrit avec précision la respiration microbienne selon la température seulement. Toutefois, la température seule n'explique pas les effets combinés de la température et la quantité d'eau liquide sur la respiration lorsque les températures sont basses. Dans cette étude, un modèle GRESP qui tient compte des effets combinés de la température et la teneur en eau des sols a été modifié et l'activation de la respiration des micro-organismes adaptés au froid dans les sols contaminés par des hydrocarbures pétroliers a été prédit avec succès. 1 INTRODUCTION Bioremediation is the use of pollutant-utilizing microbial populations for promoting degradation and/or detoxification of contaminants. Over the past two decades, a variety of inorganic and organic contaminants in soils and water has been examined in terms of the potential for bioremediation and its implementation (Bouwer and Zehnder 1993; Löffler and Edwards 2006; Lovley and Coates 1997). In particular, petroleum hydrocarbons, which are a mixture of multiple hydrocarbon compounds that include toxicants and carcinogens, are some of the most frequently identified compounds at contaminated sites in Canada (Princz et al. 2012). The feasibility of bioremediation for petroleum hydrocarbons in soils and groundwater has been extensively studied (Balba et al. 1998; Mair et al. 2013; Mueller et al. 1989). The advantage of bioremediation over other remediation methods is that significant populations of indigenous hydrocarbon-degrading bacteria are often naturally present in hydrocarbon-impacted soils and water (Whyte et al. 2002). Although indigenous hydrocarbon-degrading bacteria are required for biostimulation (i.e., stimulating the native hydrocarbon-degrading bacteria), microbial metabolisms must specifically express a substrate preference for petroleum hydrocarbons in order for biodegradation to occur in the microbial cells (Nyyssönen et al. 2008). Hydrocarbon-degrading bacteria utilize petroleum hydrocarbons (organic contaminants) as a carbon energy source, and consume oxygen (O2) and produce carbon dioxide (CO2). The CO2 production and O2 consumption, also known as

RÉSUMÉ: REMEDIATION IN NORTHERN CLIMATES: MICROBIAL RESPIRATION MODELS FOR

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Jihun Kim; Wonjae Chang (2014) Site Remediation in Northern Climates: Microbial Respiration Models for Petroleum Hydrocarbon- contaminated Soils at Low Temperatures in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper411,author = Jihun Kim; Wonjae Chang,title = Site Remediation in Northern Climates: Microbial Respiration Models for Petroleum Hydrocarbon- contaminated Soils at Low Temperatures,year = 2014}