Linking the technology of contaminant phytoextraction with the use of biochar to immobilize residual soil contaminants

目前，加拿大有许多布朗菲尔德场地受到持久性有机污染物（如多氯联苯和滴滴涕）和/或砷、镉和铅等金属的污染。植物技术被定义为“利用植物来控制、隔离、去除或降解土壤、沉积物、地表沃茨和地下水中的无机和有机污染物。“作为一个群体，这些技术在过去二十年中作为具有成本效益的非侵入性替代品或基于工程的补救方法的补充技术而获得认可。 已查明的一个研究空白是在实际受污染场地进行多年实地研究。 此外，尽管取得了公认的成功，但人们仍然关切残留污染物继续进入食物链，对环境和人类健康构成风险。 为了解决目前的研究问题，我们建议现场测试一种新的应用生物炭，从而残留污染物稳定在适当的生物炭一旦植物提取的最大量已在一个现实的时间内实现。 传统上，生物炭（一种烧焦的热处理生物质材料）已被添加到农业土壤中，以改善土壤质量并提高作物产量。 向土壤中添加生物炭也可以是一种隔离大气二氧化碳的手段。 在这里，我们提出了生物炭的另一种应用; -降低土壤中污染物的生物利用度，特别是通过利用土壤污染物残留物与生物炭的结合。 我们建议链接的过程中，i）植物提取与ii）固定残留污染物使用生物炭，并测试其联合效力在三个不同的污染地点在安大略。 除了进行多年的实地规模研究，以解决已确定的研究差距，我们将进行补充温室和实验室调查使用的土壤从三个网站。 最终，我们的目标是制定一个两步“绿色”补救方案。 第一步是通过植物提取法提取尽可能多的污染物。 第二步将涉及使用生物炭固定土壤中的任何残留污染物。

There are numerous Brownfield sites in Canada today that are contaminated with persistent organic pollutants (e.g. PCBs and DDT) and/or with metals such as arsenic, cadmium, and lead. Phytotechnologies are defined as, 'the use of vegetation to contain, sequester, remove, or degrade inorganic and organic contaminants in soils, sediments, surface waters, and groundwater.' As a group, these technologies have gained acceptance in the past two decades as cost-effective, non-invasive alternatives or complementary technologies for engineering-based remediation methods. An identified research gap is that of multi-year field studies at actual contaminated sites. In addition, despite recognized successes, concerns remain as residual contaminants, continue to enter the food chain and pose environmental and human health risks. To address current research concerns, we propose to field test a novel application of biochar, whereby residual contamination is stabilized in place by biochar once the maximum amount of phytoextraction has been achieved within a realistic time period. Traditionally, biochar (a charred, thermally-treated biomass material), has been added to agricultural soil to improve soil quality and increase crop yields. Adding biochar to soils can also be a means of sequestering atmospheric carbon dioxide. Here, we propose another application of biochar; - to reduce the bioavailability of contaminants in soil, specifically through exploiting binding of soil contaminant residues to biochar. We propose to link the process of i) phytoextraction with ii) immobilization of residual contamination using biochar, and test their joint efficacy at three different contaminated sites in Ontario. In addition to carrying out multi-year field scale studies to address an identified research gap, we will undertake complementary greenhouse and laboratory investigations using soils from each of the three sites. Ultimately, we aim to develop a two-step 'green' remediation package. The first step involves extracting the maximal amount of contaminant feasible via phytoextraction. The second step will involve immobilizing any residual contaminants in the soil using biochar.