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

今天，加拿大有许多棕地被持久性有机污染物(如多氯联苯和滴滴涕)和/或被砷、镉和铅等金属污染。植物科技的定义是“利用植物来控制、隔离、去除或降解土壤、沉积物、地表水和地下水中的无机和有机污染物。”作为一个整体，这些技术在过去二十年中已被接受为基于工程的补救方法的成本效益、非侵入性替代或补充技术。一个已确定的研究缺口是在实际污染场地进行的多年实地研究。此外，尽管取得了公认的成功，但仍然令人担忧的是，残留污染物继续进入食物链，并构成环境和人类健康风险。为了解决目前的研究问题，我们建议对生物炭的一种新应用进行现场测试，一旦在现实的时间段内实现了最大量的植物提取，生物炭就会将残留污染稳定在适当的位置。传统上，生物炭(一种烧焦的、经过热处理的生物质材料)被添加到农业土壤中，以改善土壤质量和增加作物产量。将生物炭添加到土壤中也可以是隔离大气二氧化碳的一种手段。在这里，我们提出了生物炭的另一种应用；-通过利用土壤污染物残留物与生物炭的结合来降低土壤中污染物的生物利用度。我们建议将i)植物提取过程与ii)使用生物炭固定残留污染物的过程联系起来，并在安大略省的三个不同污染地点测试它们的联合效果。除了进行多年实地研究以弥补已确定的研究差距外，我们还将利用三个地点的土壤进行互补的温室和实验室调查。最终，我们的目标是制定一个分两步走的“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.