Phytoremediation is a potentially inexpensive method of detoxifying contaminated soils using plants and associated soil microorganisms. The remote locations and cold climate of Alaska provide unique challenges associated with phytoremediation such as finding effective plant species that can achieve successful site clean-up despite the extreme environmental conditions and with minimal site management. A long-term assessment of phytoremediation was performed which capitalized on a study established in Fairbanks in 1995. The original study sought to determine how the introduction of plants (Festuca rubra, Lolium multiflorum), nutrients (fertilizer), or their combination would affect degradation of petroleum hydrocarbon (TPH) contaminated soils (crude oil or diesel) over time. Within the year following initial treatments, the plots subjected to both planting and/or fertilization showed greater overall decreases in TPH concentrations in both the diesel and crude oil contaminated soils relative to untreated plots. We re-examined this field site after 15 years with no active site management to assess the long-term effects of phytoremediation on colonization by native and non-native plants, their rhizosphere microbial communities and on petroleum removal from soil. Native and non-native vegetation had extensively colonized the site, with more abundant vegetation found on the diesel contaminated soils than the more nutrient-poor, more coarse, and acidic crude oil contaminated soils. TPH concentrations achieved regulatory clean up levels in all treatment groups, with lower TPH concentrations correlating with higher amounts of woody vegetation (trees & shrubs). In addition, original treatment type has affected vegetation recruitment to each plot with woody vegetation and more native plants in unfertilized plots. Bacterial community structure also varies according to the originally applied treatments. This study suggests that initial treatment with native tree species in combination with grasses could be an effective means for phytoremediating petroleum contaminated soils and promoting ecological recovery in cold regions.

中文翻译：

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养分添加和植物修复对亚北极阿拉斯加柴油和原油污染土壤的长期影响

植物修复是一种使用植物和相关土壤微生物对受污染土壤进行解毒的潜在廉价方法。阿拉斯加的偏远地区和寒冷气候为植物修复带来了独特的挑战，例如寻找有效的植物物种，即使在极端环境条件和最少的场地管理下，也能成功实现场地清理。对植物修复进行了长期评估，该评估利用了 1995 年在费尔班克斯建立的一项研究。最初的研究试图确定植物（羊茅、黑麦草）、养分（肥料）或其组合的引入如何影响降解石油烃 (TPH) 污染的土壤（原油或柴油）随着时间的推移。在初始治疗后的一年内，与未处理的地块相比，同时进行种植和/或施肥的地块在柴油和原油污染土壤中的 TPH 浓度总体下降幅度更大。15 年后，我们在没有积极的场地管理的情况下重新检查了该场地，以评估植物修复对本地和非本地植物的定植、它们的根际微生物群落以及从土壤中去除石油的长期影响。本地和非本地植被广泛分布在该地点，在柴油污染的土壤上发现的植被比营养更贫乏、更粗糙和酸性原油污染的土壤更丰富。TPH 浓度在所有处理组中都达到了规定的清理水平，较低的 TPH 浓度与较高数量的木本植被（树木和灌木）相关。此外，原始处理类型影响了木本植被和未施肥地块更多原生植物的每个地块的植被补充。细菌群落结构也根据最初应用的处理而变化。这项研究表明，用本地树种结合草进行初步处理可能是植物修复石油污染土壤和促进寒冷地区生态恢复的有效手段。