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

由于工业外溢、道路盐的使用和高盐工业废料的填埋，土壤盐碱化可能发生。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，加拿大有大约720万公顷的土壤受到影响。土壤盐碱化导致土壤退化，减少微生物活动，减少植物生长。它还会导致地面和地表水污染。常见的盐影响土壤修复策略包括化学改良剂的应用、填埋和封顶，这些方法通常非常昂贵、能源密集，并且会破坏土壤基质。利用维管植物清理污染场地（即植物技术）是传统修复策略的一种低成本替代方案，但迄今尚未在受盐影响的土壤中开发。在这个方案中，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，或通过专门的盐腺将其排出。当盐被排泄到茎和叶表面时，理论上它们可以被风吹散，并在大范围内重新分布。在科学文献中，以这种方式分散盐的理论被称为“盐传导”，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。考虑到像K+和Cl-这样的普通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对环境有益。这项研究很重要，因为它使用“绿色技术”解决了加拿大已知且日益严重的土壤盐碱化问题。使用植物来清理受盐影响的土壤可以改善污染场地的外观，减少我们对能源密集型技术的依赖，并减少被污染的材料进入垃圾填埋场的数量。我们的研究结果将为场地所有者提供既“环保”又具有成本效益的修复策略。

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.