| The present situation and remediation technology of oil contaminated soil has always been a hot topic in the field of ecological and environmental engineering.Biochar is widely used in remediation of oil contaminated soil.Modified biochar can increase its pore structure and adsorption characteristics,and improve its comprehensive performance.In this study,cotton straw biochar(BC)was modified by nitric acid and Fenton.The changes of microstructure and physicochemical properties of BC before and after modification were investigated by measuring the elemental composition of BC,scanning electron microscope,energy dispersive spectrometry and leaf infrared spectroscopy.In an outdoor pot experiment,biochar(BC),nitric acid modified biochar(HBC)and Fenton modified biochar(FBC)were applied to simulate oil contaminated soil with 4% oil content.The growth and Photosynthetic Physiological Indexes of sudangrass under different treatments were determined with 2% and 4% biochar,In order to provide theoretical and practical reference for the remediation of oil contaminated soil and agricultural land use technology,the effects of modified biochar and Sudan grass on the remediation of oil contaminated soil were studied.The main results are as follows:(1)After modification by nitric acid and Fenton,the p H of biochar decreased and became acidic,the contents of C,H,N and O increased significantly,and the aromaticity and polarity increased.Besides the original elements,the surface elements of biochar also appeared,such as P,S,Fe and Au,and the specific surface area expanded.The total pore volume was FBC > BC > HBC,and the surface oxygen-containing functional groups increased.Biochar modified by nitric acid and Fenton has better surface structure and adsorption properties.(2)Different biochar promoted the height growth,biomass and chlorophyll content of sudangrass.In the seedling and Tillering Stages of sudangrass,with the increase of biochar addition,the photosynthetic physiological functions of plants,such as net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr),light energy use efficiency(EU)and water use efficiency(WUE),increased,while in the jointing and heading stages of sudangrass,biochar promoted the photosynthetic performance The concentration of intercellular carbon dioxide(Ci)in the leaves of sudangrass decreased with the addition amount.The growth and Photosynthesis of sudangrass in oil contaminated soil were significantly promoted by adding biochar,which was HBC > BC > FBC.(3)The addition of different biochar had significant effects on the physical and chemical properties of oil contaminated soil.BC increased soil p H,HBC and FBC decreased soil p H,and three kinds of biochar increased soil SOM,an,TN,TP and TK.The results showed that the degradation rates of the three biochars were HBC > FBC > BC,and the degradation effect of HBC was better than FBC.Under the condition of oil content of 4%,the degradation effect of biochar treatment was better than that of Sudan grass treatment;Compared with unmodified biochar,modified biochar is more conducive to the degradation of petroleum hydrocarbons in soil,and nitric acid modified biochar is more suitable for soil amendment and pollution remediation materials.The effect of biochar combined with sudangrass on the degradation of petroleum hydrocarbons is not as good as that of biochar alone,but in the process of remediation,the contaminated soil can be used at the same time of remediation,so it can also be used as an alternative remediation approach according to the specific remediation requirements. |
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