Phytoremediation of salt impacted soils

对于上游的石油和天然气工业来说，土壤中氯化钠（盐）含量升高的问题与土壤中的石油污染一样重要。由于缺乏一种通用的、允许现场或现场修复的技术，修复受盐影响的土壤已被证明是困难和昂贵的。植物修复（基于植物的生物修复）与传统的去除或基于化学的修复方法相比具有许多优点。不幸的是，盐胁迫通常会导致乙烯（一种植物应激激素）的产生增加，并导致植物生长减缓。没有高水平的生物量，就无法实现可接受的补救率。我们最近开发的用于石油修复的多过程植物修复系统（MPPS）在盐侵蚀土壤的修复中具有潜在的应用前景。该生物系统的一个关键特征是利用植物生长促进菌（PGPR）缓解植物胁迫。这些PGPR消耗植物激素乙烯的前体，从而减少植物中乙烯的生物合成。因此，在受盐影响的土壤上可以实现旺盛的植物生长，并应促进土壤中盐的修复。在我们的先导实验中，最有希望获得结果的pgpr是两个恶臭假单胞菌菌株（UW3和UW4）。这些是我们目前用于石油修复的天然PGPR菌株。它们在加拿大环境部的安全和非致病性微生物名单上。总的来说，我们观察到PGPR至少使植物发芽率和植物总生物量增加了100%。我们在温室试验中对盐的修复进行了分析。在这个节骨眼上，结果还没有定论。为了准确地评估盐修复，我们需要更多的数据和更长的生长周期。今年冬天，我们将在温室里种植更长时间的植物，以便在每个实验中进行更多的修复。春季，我们将在阿尔伯塔省3个受盐影响的地点进行实地试验。这些地点与上游石油和天然气工业有关，并且有不同程度的盐污染。

The problem of elevated sodium chloride (salt) levels in soils is as important as petroleum contamination of soils for the upstream oil and gas industry. The remediation of salt impacted soils has proven difficult and costly due to the absence of a technology that is versatile and allows for in-situ or on-site remediation. Phytoremediation (plant-based bioremediation) offers many advantages over conventional removal or chemical-based remediation methods. Unfortunately, salt stress often leads to increased production of ethylene, a plant stress hormone, and results in diminished plant growth. Without high levels of biomass acceptable rates of remediation can not be achieved. Our recently developed multi-process phytoremediation system (MPPS) used for petroleum remediation has potential applications for remediation of salt impacted soils. A key feature of this biological system is the alleviation of plant stress by using plant growth promoting rhizobacteria (PGPR). These PGPR consume the precursor to the plant hormone ethylene, thus decreasing ethylene biosynthesis in plants. As a result, vigorous plant growth on salt impacted soils can be achieved, and should facilitate remediation of salt from the soil. In our pilot experiments, the PGPRs with the most promising results were two Pseudomonas putida strains (UW3 and UW4). These are the naturally occurring strains of PGPR that we currently use for petroleum remediation. They are on Environment Canada's list of safe and non-pathogenic microbes. In general, we are observing at least a 100 % increase in plant germination and total plant biomass attributable to PGPR. We have assayed for salt remediation in a greenhouse experiment. The results are inconclusive at this juncture. To accurately assess salt remediation we need more data and longer growth periods. This winter in the greenhouse, we will grow plants for longer time periods, allowing more remediation to occur within each experiment. In the Spring, we will proceed with field experiments at 3 salt-impacted sites in Alberta. These sites are associated with the upstream oil and gas industry, and have varying levels of salt contamination.