椰纤维生物炭及其硝酸改性对稻田土壤中Pb钝化的影响  

Effect of Coconut Fiber Biochar and Its Nitrate Modification on Pb Passivation in Paddy Soils

作　　者：侯正伟 李建宏 李财生 张婧旻 林清火[2] 赵庆杰[3] 吴治澎[1] 王禹 HOU Zheng-wei;LI Jian-hong;LI Cai-sheng;ZHANG Jing-min;LIN Qing-huo;ZHAO Qing-jie;WU Zhi-peng;WANG Yu(College of Tropical Crops,Hainan University,Haikou 570228,China;Rubber Research Institute,Chinese Academy of Tropical Agricultural Sciences,Haikou 571101,China;College of Forestry,Hainan University,Haikou 570228,China;Hainan Key Laboratory of Arable Land Conservation,Haikou 571100,China)

机构地区：[1]海南大学热带作物学院,海口570228 [2]中国热带农业科学院橡胶研究所,海口571101 [3]海南大学林学院,海口570228 [4]海南省耕地保育重点实验室,海口571100

出　　处：《环境科学》2023年第8期4497-4506,共10页Environmental Science

基　　金：海南省自然科学基金项目(321MS006);海南省教育厅项目(Hnky2021-ZD-8);中央级公益性科研院所基本科研业务费专项(1630022022030)。

摘　　要：通过土壤培养实验,并结合扫描电镜(SEM)、X射线光电子能谱(XPS)、同步辐射X射线荧光(μ-XRF)和傅立叶变换红外吸收光谱(FTIR)等光谱学技术,探明椰纤维生物炭(CFB)和硝酸改性椰纤维生物炭(NCFB)对稻田土壤钝化外源铅(Pb)的效果及其内在机制.与CFB相比,NCFB蜂窝状孔内壁更粗糙,且硝酸改性后CFB表面含C—O结构的醇酚醚类官能团量明显降低,含C==O/O==C—O结构的羧基类的官能团量明显增加.相较于培养150 d后的对照(不添加生物炭)稻田土壤,添加CFB和NCFB的稻田土壤中EDTA提取态Pb含量分别降低了39.7%和105.4%.添加NCFB的土壤中碳酸盐结合态和铁锰氧化物结合态Pb含量显著降低且有机结合态和残渣态Pb含量则显著升高,SRXRF扫描结果可知外源Pb在富含Ca和Cu元素的CFB颗粒微区大量富集,在富含Fe、Mn和Ti元素的土壤团聚体微区富集相对较少.另外,培养实验中,相较于无外源Pb时A-CFB和A-NCFB,有外源Pb时A-CFBPb和A-NCFBPb中的羧酸盐特征峰(1384 cm^(-1))明显增强.添加CFB或NCFB对钝化稻田土壤中外源Pb的效果较好,且能促进稻田土壤中Pb由不稳定的形态逐渐向更稳定的形态转化,达到钝化Pb的效果,NCFB中更大量的羧基官能团参与外源Pb的钝化,使得NCFB钝化Pb的效果优于CFB.NCFB由于其蜂窝状孔内壁更粗糙以及丰富的羧基官能团,对钝化稻田土壤中外源Pb的效果比CFB好,在海南等热带地区,可考虑将椰纤维生物炭及其改性作为一种修复土壤铅污染的环境友好型候选方法.The effects of coconut fiber biochar(CFB)and nitrate-modified coconut fiber biochar(NCFB)on the passivation of exogenous lead(Pb)in paddy soils and their underlying mechanisms were investigated using soil incubation experiments combined with spectroscopic techniques such as scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),synchrotron radiation X-ray fluorescence(SRXRF),and Fourier transform infrared absorption spectroscopy(FTIR).The effects of NCFB and CFB on the passivation of exogenous lead(Pb)in paddy soils and its underlying mechanisms were investigated.Compared with that of CFB,the inner wall of NCFB honeycomb pores was rougher,and the amount of alcohol-phenol-ether functional groups containing the C—O structure and the amount of carboxyl groups containing the C====O/O C—O structure on the surface of CFB was significantly decreased after nitric acid modification.Compared with that in the control(without biochar)paddy soil after 150 d of incubation,the EDTA-extracted Pb content in the paddy soil with CFB and NCFB was reduced by 39.7%and 105.4%,respectively.The carbonate-bound and Fe-Mn oxide-bound Pb contents were significantly lower,and the organic-bound and residue Pb contents were significantly higher in the NCFB-added soil.The SRXRF scans showed that the exogenous Pb was enriched in the microregions of CFB particles rich in Ca and Cu elements and relatively less so in the microregions of soil aggregates rich in the Fe,Mn,and Ti elements.In addition,the characteristic peaks of carboxylates(1384 cm^(-1))in A-CFBPb and A-NCFBPb were significantly enhanced in the incubation experiment in the presence of exogenous Pb compared to A-CFB and A-NCFB in the absence of exogenous Pb.The addition of CFB or NCFB was more effective in passivating exogenous Pb in paddy soils and promoted the gradual transformation of Pb from unstable to more stable forms in paddy soils to achieve the effect of passivating Pb.The greater amount of carboxyl functional groups in NCFB participated in the passivatio

关 键 词：生物炭 硝酸改性 稻田土壤 重金属 Pb形态 

分 类 号：X171.5[环境科学与工程—环境科学]