Elucidating the mechanisms utilized in phytotechnolgies and biochar immobilization to optimize contaminated site remediation

持久性有机污染物是一种顽固性污染物，已知会对生态和人类健康造成一系列影响。由于当前的农业实践和工业过程，土壤盐分是一个日益严重的问题，也是影响植物生长和产量的主要非生物胁迫之一。同样，由于近几十年来加拿大石油和天然气行业的活动不断升级，石油碳氢化合物（PHCs）污染是许多加拿大人最关心的问题。至少在一定程度上，这些污染物中的每一种都可以通过被称为“植物技术”（或植物修复）的创新植物技术来解决。植物提取是一种特殊的植物技术，通过这种技术，污染物被植物根部吸收，转移到芽部，然后被隔离在地上的植物组织中。然后收获植物并进行生物量减少（例如堆肥），其目标是显著减少受污染废物的总量，同时保持土壤基质完整。在过去的六年中，我的小组在污染物植物提取领域取得了几项重大进展，包括使用本地殖民者。在同一时期，我们率先使用生物炭（一种由有机物在极低氧条件下热解产生的类似木炭的物质）来降低土壤中污染物的生物有效性，降低其对环境和人类健康的风险，同时改善土壤质量并减少二氧化碳排放。这些创新技术现在开始得到更广泛的应用，然而，对植物吸收污染物和土壤稳定的过程仍然缺乏基本的了解，生物炭在土壤微生物群落和植物健康中所起的作用也是如此。这一建议将解决这些缺点，并进一步加深我们对植物提取机制的理解。我们将使用我的小组开发的方法，例如测量离根不同距离的本地植物木质部汁液中的污染物。应用群落水平生理分析（CLPP）获得污染土壤中微生物群落功能的表型信息，以及生物炭修饰的土壤，是我小组开发的另一种创新工具。这些新兴技术的新应用与温室试验结合使用真实的土壤和植物系统将扩大我们对土壤污染物，植物和微生物群落之间相互作用的理解。将这项关键的植物提取工作与生物炭对土壤的修正相结合，将使我们对植物体内污染物吸收和流动的机制有更深入的了解，并使我们能够研究土壤微生物种群的重要变化。这将使我们有能力在植物提取地块的根区加强污染物的降解，特别是PHCs。因此，利用现有的植物提取和碳修正固定化技术（结合新兴的木质部汁液分析、CLPP和生物炭方法），本提案将探索同时使用这些技术来修复POPs、盐和phc影响的地点的效果。最终，这项工作的目标是确定植物技术与生物炭如何最好地相互作用，以优化污染场地的修复。这样做，这些技术将变得更加被接受和主流，为受污染场地的所有者、政府立法机构和环境顾问提供他们在修复受污染场地时将其纳入“工具箱”所需的信息。

Persistent organic pollutants (POPs) are recalcitrant contaminants known to cause a number of ecological and human health effects. Soil salinity is an escalating problem due to current agricultural practices and industrial processes, and is one of the major abiotic stresses that affect plant growth and yield. Similarly, contamination with petroleum hydrocarbons (PHCs) is at the forefront of many Canadians minds given the escalation in activity in the oil and gas industry in Canada in recent decades. Each of these contaminants can be addressed, at least to some extent, using innovative plant-based techniques known as ‘phytotechnologies’ (or phytoremediation). Phytoextraction is a specific phytotechnology whereby contaminants are taken up by plant roots, translocated to the shoots, and then sequestered in the above-ground plant tissue. Plants are then harvested and undergo biomass reduction (e.g. composting), with the goal being to significantly reduce the total volume of contaminated waste, while leaving the soil matrix intact. In the past six years, my group has made several significant advances in the area of contaminant phytoextraction, including the use of native colonizers. During the same time period, we have pioneered the use of biochar (a charcoal like material produced from the pyrolysis of organic matter under very low oxygen conditions) to decrease the bioavailability of contaminants in soils, reducing their risk to environmental and human health, and at the same time improving soil quality and decreasing CO2 emissions. These innovative techniques are now starting to be utilized more widely, however, a fundamental understanding of the processes involved in contaminant uptake into plants, and stabilization within soils is still lacking, as is the role that biochar plays in soil microbial communities and in the health of plants. This proposal will address these shortcomings and further our understanding of the mechanisms of phytoextraction. We will use methods developed by my group, such as measuring contaminants in the xylem sap of native plants at varying distances from the root. The application of community-level physiological profiling (CLPP) to obtain phenotypic information regarding microbial community function in contaminated soils alone, and those amended with biochar, is another innovative tool developed by my group. The novel use of these emerging techniques in combination with greenhouse trials employing real soil and plant systems will broaden our understanding of interactions between soil contaminants, plants, and the microbial community. Carrying out this critical phytoextraction work in combination with biochar amendment to the soil, will provide us with a deeper appreciation of the mechanisms involved in contaminant uptake and mobility within plants, and allow us to examine important changes in the microbial soil population. This will lead to our ability to also enhance the degradation of contaminants, in particular PHCs, in the root zone of phytoextraction plots. Hence, using established phytoextraction and carbon amendment immobilization techniques (combined with the emerging methods of xylem sap analysis, CLPP and biochar), this proposal will explore the efficacy of using these technologies simultaneously to remediate POPs-, salt-, and PHC-impacted sites. Ultimately, the goal of this work is to determine how phytotechnologies in conjunction with biochar can best interact to optimize contaminated site remediation. In so doing, these technologies will become more accepted and mainstream, providing contaminated site owners, government legislatures, and environmental consultants with the information they need to incorporate them into their ‘toolbox’ when remediating contaminated sites.