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

由于工业泄漏、道路盐的应用以及高含盐量的工业废物的填埋，可能会发生土壤盐碱化。不管污染的方式如何，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720万公顷的土壤受到影响。土壤盐碱化导致土壤退化，降低微生物活性，减少植物生长。它还可能导致地下水和地表水污染。受盐分影响的土壤的常见修复策略，包括应用化学改良剂、填埋和封顶，通常都非常昂贵、能源密集型，而且会破坏土壤基质。使用维管植物清理受污染的场地(即植物技术)是传统修复策略的低成本替代方案，但到目前为止，尚未在受盐分影响的土壤中开发。在这项提议中，我们使用耐盐植物，即盐生植物，从受污染的土壤中吸收盐离子，并将其隔离在植物组织中，或通过特殊的盐腺将其排泄出来。当盐在茎和叶表面排泄时，理论上它们可以被风吹散，并重新分布在大片区域。这种理论上的盐扩散在科学文献中被称为“卤化电导”，但从未在实验室或田间试验中得到证实。我们建议在工业现场和实验室使用各种不同的技术来测量排泄物中盐类的扩散。然后，这些信息将被用于创建盐分散的模型。鉴于K+和Cl-等常见盐离子是植物和动物的营养物质，它们在大范围内的扩散实际上可能对环境有利。这项研究很重要，因为它解决了加拿大土壤盐碱化的已知和日益严重的问题，使用了一种“绿色技术”。使用植物来清理受盐分影响的土壤，改善了受污染场地的外观，减少了我们对更多能源密集型技术的依赖，并减少了进入垃圾填埋场的受污染物质的数量。我们的研究结果将为网站所有者提供一种既环保又经济的补救策略。

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.