纳米羟基磷灰石对污染土壤镉钝化效应研究

发布时间：2018-01-21 01:44

  本文关键词： 纳米羟基磷灰石 微生物 土壤 镉 油菜　出处：《河北大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着现代农业技术的快速发展以及农药化肥的不合理利用,在造成农业减产、食品质量安全下降的同时,土壤质量问题日益严重。土壤污染尤其重金属镉污染问题相对突出。如何在当前确保农业耕地红线的前提下,保障农产品和土壤环境安全成为农业、环境及食品工作领域的重点关注话题。本文在大量文献调研的基础上,通过室内模拟实验探索了纳米羟基磷灰石(NHAP)对重金属镉在土壤中淋溶特征的影响,明确了不同比例纳米羟基磷灰石施加后土壤镉含量和形态的转化规律。在纳米羟基磷灰石与微生物(枯草芽孢杆菌、白腐真菌)协同作用下,镉在土壤和植株中的分布规律及植物根际土壤微生物种群变化。主要研究结果如下:1.纳米羟基磷灰石(NHAP)对溶液中镉离子的吸附率和解吸率随时间延长、温度上升均呈先升高后趋于稳定;随溶液pH升高,纳米羟基磷灰石对镉离子的吸附率快速上升后基本稳定,解吸率随pH升高后迅速降低,在pH为3时基本稳定。2.通过模拟土柱实验评价NHAP处理对污染土壤中Cd原位固定效果及形态变化规律。结果表明:NHAP的输入增加了土壤的pH,而且土壤镉经NHAP钝化稳定化后由生物有效态向稳定态转化。土壤淋出液中镉浓度经不同模型拟合,抛物线扩散模型的R2最大,达到0.998,以此推断在酸雨间歇淋失条件下,经NHAP处理的镉污染土壤50年后浸出液中镉浓度不会对人体健康造成危害。3.室内模拟盆栽实验,研究纳米羟基磷灰石的不同施加比例对镉污染土壤的钝化修复效果。结果表明:NHAP施加显著增加油菜株高生物量,且随NHAP施入量的增加,油菜中Cd含量显著下降,施入量为0.2%、0.5%和1%时,分别比对照降低22.38%,36.25%和50.2%。NHAP施加可显著提高土壤生物学质量,与对照相比,NHAP处理镉污染土壤过氧化氢酶、脲酶和碱性磷酸酶的活性显著增加,且过氧化氢酶和碱性磷酸酶活性随施加量的增加显著提高。对比不同纳米羟基磷灰石添加比例对植物、土壤修复效果,0.5%(W/W)的纳米羟基磷灰石的施加比例为较优修复处理。4.以0.5%(W/W)纳米羟基磷灰石为修复基础,分别联合枯草芽孢杆菌、白腐真菌,通过盆栽实验,研究纳米羟基磷灰石-微生物联合作用对镉污染土壤钝化修复效果。结果表明,NHAP和微生物的联合作用显著提高了油菜株高生物量,油菜植株中Cd累积量显著降低,各处理油菜植株中Cd含量分别比CK处理减少37.99%-57.04%。同时,由于油菜吸收量的降低,在植物-土壤体系镉稳定平衡的前提下,施加NHAP-微生物各处理土壤中镉残留量较对照提高7.01%-16.77%。BCR顺序提取法分析表明NHAP与微生物联合作用促进土壤Cd由交换态向Cd残渣态转化。分析土壤生物学质量表明,NHAP与微生物联合作用不同程度地提高了镉污染土壤中过氧化氢酶、脲酶和碱性磷酸酶活性。而且,相较枯草芽孢杆菌和白腐真菌,NHAP施加对土壤中细菌种群丰富度和多样性有显著影响,镉污染土壤加入NHAP后,群落丰富度和细菌多样性均显著增加,变形菌门、放线菌门等种群增多,有益菌Paenibacillus(类芽孢杆菌)等显著增加,有害菌Gemmata(出芽菌属)等显著减少,使土壤向健康方向发展。综上,本研究表明,纳米羟基磷灰石对镉污染土壤呈现较好的钝化修复效果,土壤pH的升高与镉离子形成磷酸盐沉淀,降低了土壤中生物有效态镉含量和浓度,且镉污染土壤钝化修复过程中纳米羟基磷灰石与功能微生物呈现较好的协同作用,其吸附钝化功能共同促进有效态镉向稳定态转化,为中低浓度镉污染土壤长期稳定和可持续发展提供材料支持和技术补充。
[Abstract]:With the rapid development of fertilizer and pesticide is not reasonable use of modern agricultural technology, resulting in agricultural production, food safety and quality decline at the same time, the soil quality problems become more and more serious soil pollution. Especially the cadmium pollution problem is relatively prominent. How to ensure the premise of agricultural land in the red line under the protection of agricultural products and agricultural soil environmental security has become topic, focus on the environment and food field. In this paper, on the basis of literature research, through the indoor simulation experiment on the nano hydroxyapatite (NHAP) effect of cadmium on the leaching characteristics, clear the different proportion of nano hydroxyapatite and transformation of soil cadmium content and morphology after applying in nano hydroxyapatite and microbial. (Bacillus subtilis, white rot fungi) synergy, cadmium distribution and plant in the soil and plant rhizosphere Soil microbial population changes. The main results are as follows: 1. nano hydroxyapatite (NHAP) on the adsorption rate and desorption rate of cadmium ion in the solution with time, temperature rise were firstly increased and then tended to be stable; with the increase of solution pH, nano hydroxyapatite on the cadmium ion adsorption rate increased rapidly after the basically stable, with the desorption rate pH increased and then decreased rapidly when the pH is 3 stable.2. through soil column simulation experiment to evaluate NHAP treatment on the changes of fixed effect and morphology in Cd contaminated soil in situ. The results show that the input of NHAP increased soil pH, and soil cadmium by NHAP passivation after stabilization by biological effective state to a stable state transformation of soil leaching. The cadmium concentration in liquid by different fitting model, diffusion model R2 is the largest, reaching 0.998, in order to infer the intermittent leaching in acid rain conditions, the cadmium contaminated soil NHAP treatment after 50 years of leaching solution The Cd concentration in the.3. will not cause harm to human health indoor simulation and pot experiment, remediation effect of different proportion of applying nano hydroxyapatite passivation on the cadmium contaminated soil. The results showed that NHAP exerted significantly increased plant height and biomass, with the increase of NHAP application rate, Cd content in rape decreased significantly, the amount of applied for 0.2%, 0.5% and 1%, respectively, decreased by 22.38%, 36.25% and 50.2%.NHAP applied can significantly improve soil biological quality, compared with the control group, NHAP treatment of cadmium contaminated soil enzyme catalase, urease and alkaline phosphatase activity increased significantly, and the catalase and alkaline phosphatase activity increased with the increase of the amount increased significantly. Compared with different nano hydroxyapatite the proportion of plants, soil remediation, 0.5% (W/W) nano hydroxyapatite is applied as the optimal repair ratio of.4. to 0.5% (W/W) nano hydroxyapatite 鐏扮煶涓轰慨澶嶅熀纭，

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