Remediation of Ni toxicity by liming - field validation

被金属污染的土壤的修复可以通过施用农业石灰来实现，这有望通过增加土壤pH来减少植物可利用的金属。然而，提高pH可能会降低必需元素的生物有效性，这可能会对作物产量产生负面影响。本研究将重新考察科尔伯恩港（ON）一组镍、铜、钴和砷含量较高的农田，这些农田在十年前以10或50吨/公顷的速度用白云石石灰进行了改良，并在随后的三年中确定了燕麦和大豆的产量。这些土地将重新种植大豆，以评估石灰化作为一种补救策略的长期效果（目标1）。这些数据将与最近施用88吨/公顷石灰的农田大豆的农艺产量进行比较（目标2）。比较了钙质石灰和白云石石灰对大豆农艺产量的影响。在这两个领域，农艺反应和镍的组织积累将与土壤总镍、已知可改变生物有效性的土壤化学参数、土壤溶液镍和植物有效镍有关（目标3）。一种替代石灰作为修复策略是通过植物修复降低表层土壤中的镍浓度。使用Ni超蓄能器（Alyssum murale），盆栽和现场研究将提供土壤到植物转移的数据，这些数据将用于填充STELLA®模型，该模型允许随着时间的推移模拟系统。结果将是估计在许多不同情景下表层土壤中镍的半衰期（目标4）。最后，将评估“深耕”对表面污染稀释的潜力，以及将较不肥沃的B层土壤带入根区对作物生产力的预期损失（目标5）。这些研究的整合将使该地点的土壤修复策略决策支持系统成为可能，该系统也可应用于加拿大其他金属污染地区（如棕地）。新知识将通过发展和展示适合大规模使用的实际农业干预措施，而不是技术密集型工艺，支持加拿大采矿业在世界范围内具有竞争力。

Remediation of soils contaminated with metals may be achieved through application of agricultural lime, which is expected to reduce plant-available metal by increasing soil pH. However, raising the pH can potentially reduce the bioavailability of essential elements, which may negatively impact crop yields. The present study will revisit a set of agricultural fields in Port Colborne (ON) elevated in Ni, Cu, Co, and As, which were amended with dolomitic lime at either 10 or 50 t/ha a decade ago and yields of oat and soybean were determined in three subsequent years. These fields will be replanted with soybean to evaluate the long-term efficacy of liming as a remediation strategy (Objective 1). These data will be compared to agronomic yield of soybean in fields more recently amended with 88 t/ha of lime (Objective 2). The effect of calcitic versus dolomitic lime on agronomic yield of soybean will be compared in two sets of fields. For both fields, agronomic response and tissue accumulation of Ni will be related to total soil Ni, soil chemistry parameters known to modify bioavailability, soil solution Ni and plant available Ni (Objective 3). An alternate to liming as a remediation strategy is reducing the Ni concentration in surface soils through phytoremediation. Using a Ni hyperaccumulator (Alyssum murale), pot and in situ field studies will provide data of soil to plant transfer which will be used to populate STELLA® models, which allow simulation of a system over time. The outcome will be estimates of the half-life of Ni in surface soils under a number of different scenarios (Objective 4). Finally, the potential for dilution of surface contamination by 'deep tilling' versus the expected loss in crop productivity by bringing less fertile B horizon soils into the root zone, will be evaluated (Objective 5). Integration of these studies will enable a decision support system for soil remediation strategies for this site, which can also be applied to other metal-contaminated areas in Canada (e.g. brownfields). The new knowledge will support the Canadian mining industry in being competitive worldwide by developing and demonstrating practical agronomic interventions suitable for large-scale use, rather than technology-intensive processes.