A comprehensive framework for determining efficient bioremediation strategies for petroleum hydrocarbon-contaminated soils in cold regions

在加拿大北方领土有大量的石油烃污染场地，生物补救办法，即土壤微生物将有害的石油烃化合物转化为危害较小或无害的产品，被认为是清理这些场地的一种具有成本效益的技术。然而，寒冷地区的低温可能会限制微生物降解活性，因此需要对土壤加热或优化不同温度制度的生物修复，以提高生物修复性能。在北方地区，通过向污染土壤中添加营养物质、水分和氧气进行生物刺激可以增强微生物活性。然而，目前还不清楚生物刺激是否可以只针对碳氢化合物降解微生物群落，而不是可能不参与碳氢化合物生物降解的其他土壤微生物。这项研究将系统地评估温度制度和生物刺激如何影响微生物群落的组成和活性，以及营养添加的时机是否可以导致更有效的生物修复操作适应低温。对新的生物刺激方法的评估将基于从微观世界收集的数据，以及使用不同地点土壤和与地点相关的不同温度制度运行的中试规模生物反应器。污染物中残留的、未降解的部分高于监管的清洁水平，这是一个常见的挑战。作为本研究的一部分，我们将评估土壤团聚体的微观结构，特别是土壤团聚体内部的孔隙比例，土壤微生物无法进入，是否是生物修复终点的决定因素。这些研究将与工业伙伴魁北克水电公司密切合作进行，魁北克水电公司对北部及其社区的可持续发展感兴趣。 本科生、博士生和博士后学生将在该项目中接受关于在北方场地进行有效生物补救的新方法的培训。

There are a significant number of petroleum hydrocarbon-contaminated sites in Canadian northern territories and bioremediation, where soil microbes transform hazardous petroleum hydrocarbon compounds to less hazardous or non-hazardous products, is considered a cost-effective technology for clean up of those sites. However, low temperatures in cold regions may limit microbial degradation activity, and thus soil heating or optimizing bioremediation for different temperature regimes is required for improving bioremediation performance. Biostimulation by addition of nutrients, moisture, and oxygen to the contaminated soils can enhance microbial activity in northern sites. However, it is unclear if biostimulation can be tailored to the hydrocarbon-degrading microbial community only, rather than other soils microbes that may not be involved in hydrocarbon biodegradation. This study will systematically assess how temperature regimes and biostimulation affect the microbial community composition and activity, and if the timing of nutrient addition could lead to more efficient bioremediation operations adapted to low temperatures. The assessment of new biostimulation approaches will be based on data collected from microcosms and as well as pilot-scale bioreactors operated using various site soils and at different temperature regimes relevant to the sites. Residual, un-degraded fractions of contamination that are above regulatory clean-up levels is a common challenge. As part of this study, we will assess if the soil aggregate micro-structure and in particular, the fraction of pores inside soil aggregates which are not accessible to soil microorganisms, is a determining factor for bioremediation endpoints. The studies will be conducted in close collaboration with the industrial partner, Hydro-Quebec, who is interested in the sustainable development of the north and its communities. Undergraduate, PhD and postdoctoral students will be trained in this project on new approaches for effective bioremediation in northern sites.