生物炭对典型多元素污染土壤中重金属迁移能力的影响研究

Biochar, a form of black carbon results from incomplete-burning biomass, can be used to immobilize heavy metal in water phase by both surface adsorption and partitioning mechanisms.However,this mechanisims were not defintude under the complex soil conditions.This project intends to research biochar effects on all heavy metal elements mobility in typical polluted soils from Guizhou provience.Several biochar are going to be producted by using the readily available materials, such as rice straw, corn stalks, hardwood and some animal wastes. And then, the adsorption ability and partitioning mechanisms about these biochar works on Hg、Pb、Cd、As、Sb、Ti,etc.were be clarified by batch experiments, combing with the principium of fertilization recommendation technique, the application rate of biochar was considerately estimated. Furthermore,biochars were fertilized in the polluted soils,and heavy metals in soils before and after fertilization were analyzed by three-stage BCR sequential extraction procedure to verify the improvement of the soils. It was believed that the different biochar effects on the heavy metal mobility in different soils,therefore, the finally aim of this research was calculated out the optimization suggestion on biochar as a soil remediation reagents.

生物炭是生物质不完全燃烧的产物，它可以通过表面吸附和分配机制影响重金属的迁移性,但这些作用机制尚不能够完全解释在复杂的土壤条件下,生物炭与重金属的作用规律。本项目拟以贵州典型的多重金属污染土壤为研究对象，采用易于获取的水稻秸秆、玉米秸秆、木屑以及动物粪便等材料制备出生物炭，重点弄清这些生物炭对Hg、Pb、Cd、As、Sb、Ti等重金属的吸附规律，结合测土施肥技术的基本原理，确定生物炭施用量，通过对改良前后土壤重金属化学提取形态的分析，研究不同生物炭施对土壤重金属迁移能力影响程度，从而为生物炭技术应用于土壤重金属污染控制提供直接的理论依据和科技支撑。

生物炭作为土壤改良剂，因其制作原理简单，成本低廉，且副作用小，近年来广受重视。然而，生物炭作为重金属修复其作用效果和作用规律尚待系统研究。本研究采用水稻秸秆（RS）、玉米秸秆（CS）、木屑（HW）和鸡粪（BL）为原材料，依照正交研究方案的设计，分别在250℃、300℃、350℃、450℃、650℃的热解温度和30min、60min、90min、120min、180min的热解时间条件下制备生物炭。测定了各种生物炭的产率、灰分含量、pH值、零电荷点、比表面积和表面官能团含量等理化性质。通过吸附动力学研究、等温吸附研究、不同溶液初始pH值对吸附的影响研究以及不同温度制备的生物炭对吸附的影响研究，评价了吸附性能。通过在土壤中添加生物炭的培养研究表明，生物炭对土壤种重金属有效态含量具有一定影响。除As、Sb、 Cr、以外，添加生物炭后，土壤中Hg、Pb、Zn、Cd、Cu等重金属有效态含量均呈现了不同程度的降低。通过在土壤中添加生物炭并种植白菜的盆栽试验研究表明，生物炭可有效降低叶菜类农作物对Hg、Pb、Zn、Cd、Cu等重金属的吸收，显著降低了这些重金属的迁移性。生物炭对Cr迁移移性影响则相对较小。此外生物炭却促进了植物对AS、Sb的吸收。生物炭用于土壤修复需从污染物种类、污染物水平，并要充分考虑食品安后，开展具体应用和推广。