Remediation of Cement Kiln Dust (CKD)-contaminated sites using excretory halophytes: Quantification, optimization and modelling of salt extraction and dispersion

土壤盐碱化可能是由于工业泄漏，道路盐的应用，以及高含盐量工业废料的填埋。 无论污染的方式如何，土壤盐碱化在加拿大和全世界都是一个日益严重的问题，据估计，加拿大有超过720万公顷的土壤受到影响。 土壤盐碱化导致土壤退化，减少微生物活性，并减少植物生长。 它还可能导致地下水和地表水污染。 盐影响土壤的常见修复策略包括应用化学改良剂、填埋和覆盖通常非常昂贵、能源密集，并破坏土壤基质。 使用维管植物清理污染场地（即植物技术）是传统补救策略的低成本替代方案，但迄今为止，尚未在受盐影响的土壤中使用。 在这个提案中，我们采用耐盐植物（称为盐生植物）来从受污染的土壤中吸收盐离子，并将它们隔离在植物组织中，或者通过专门的盐腺将它们排泄出去。 当盐被排泄到茎和叶的表面时，理论上它们可以随风飘散，并在大面积上重新分布。 在科学文献中，盐以这种方式的理论扩散被称为“盐圈传导”，但从未在实验室或现场试验中得到证实。 我们建议在工业现场和实验室中使用各种不同的技术来测量排泄盐的分散。 然后，这些信息将用于创建盐分散模型。 考虑到常见的盐离子，如K+和Cl-是植物和动物的营养物质，它们在大范围内的分散实际上有利于环境。 这项研究是重要的，因为它解决了已知的和日益严重的问题，土壤盐碱化在加拿大使用“绿色技术”。 利用植物清理受盐影响的土壤可以改善受污染场地的外观，减少我们对能源密集型技术的依赖，并减少进入垃圾填埋场的污染材料数量。我们的研究结果将为场地所有者提供一种既“环保”又具有成本效益的补救策略。

Soil salinization can occur due to industrial spills, the application of road salt, and the landfilling of high salt content industrial waste materials. Regardless of the mode of contamination, soil salinization is a growing problem both in Canada, where it is estimated that >7.2 million ha of soil are affected, and word wide. Soil salinization leads to the degradation of soil, reduces microbial activity, and diminishes plant growth. It can also lead to ground and surface water contamination. Common remediation strategies for salt-impacted soils including the application of chemical amendments, landfilling, and capping are typically very expensive, energy intensive, and destroy the soil matrix. The use of vascular plants to clean up contaminated sites (i.e. phytotechnology) is a low cost alternative to conventional remediation strategies, but has to date, not been exploited in salt-impacted soils. In this proposal, we employ salt-tolerant plants, known as halophytes, to take up salt ions from contaminated soil and either sequester them in the plant tissue, or excrete them through specialized salt glands. When salts are excreted on stem and leaf surfaces, they can theoretically be dispersed on the wind and redistributed across a large area. The theoretical dispersal of salt in this manner is referred to as 'haloconduction' in the scientific literature, but has never been demonstrated in laboratory or field trials. We propose to measure the dispersal of excreted salts using a variety of different techniques both at an industrial field site, and in the laboratory. This information will then be used to create a model of salt dispersion. Given that common salt ions such as K+ and Cl- are plant and animal nutrients, their dispersal over a wide area could actually benefit the environment. This research is important as it addresses the known and growing problem of soil salinization in Canada using a 'green technology'. Using plants to clean up salt-impacted soils improves the appearance of contaminated sites, decreases our reliance on more energy-intensive technologies, and reduces the amount of contaminated material going to landfills. Our results will provide site owners with a remediation strategy that is both 'environmentally friendly' and cost-effective.