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531.
北京东郊土壤中某些重金属的含量、形态、相互关系及其在环境质量评价中的意义 总被引:5,自引:2,他引:5
本文讨论了土壤中某些重金属的含量、形态、它们之间的关系以及它们在环境质量评价中的意义.在野外情况下.残留态是镉的主要形态.用NH_4OAC提取的六种重金属百分率的序列为:Cd(12.97)>Cu(1.32)>Ni(1.06)>Zn(0.51)>Pb(0.24)>Cr(0.09).DTPA提取的序列为:Cd(33.10)>Cu(20.52)>Zn(4.25)>Ni(1.19)>Pb(0.93)>Cr(0.16).土壤中镉的存在形态取决于应用到土壤中的镉化物的种类.北京东郊土壤中相当一部分镉是以较易溶解的镉化物存在的.土壤中重金属的总量之间,NH_4OAC提取的、DTPA提取的量和总量之间都显著相关.用相关方程计算的六种重金属的含量进行了一次土壤质量综台评价.计算的评价值与实际评价值十分一致 相似文献
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Tu Chuang Mu Xianzhong Wu Yufeng Gu Yifan Hu Guangwen 《Environment, Development and Sustainability》2022,24(8):10089-10117
Environment, Development and Sustainability - The undergoing rapid urbanization is bringing dramatic economic development and social improvement for cities, but also a series of problems associated... 相似文献
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通过室内循环冻融循环试验和三轴不固结不排水(UU)压缩试验研究了循环冻融作用与细砾组含量(P_(2-5))对黏质粗粒土抗剪性能的影响。结果表明,冻融循环作用对黏质粗颗粒土的应力—应变曲线性状具有一定的影响,可使其由未冻融的应变软化向应变硬化转变的趋势,但随着细砾组P_(2-5)含量的增加,冻融作用对其影响逐渐减弱。随着冻融循环次数的增加,土样剪切强度呈现逐渐衰减,且在5~9次冻融循环次数后基本保持不变,多次循环冻融作用后剪切强度最大衰减幅度可达40%。弹性模量随冻融循环次数的增加上下波动较大但整体呈现下降趋势。在抗剪强度指标方面,冻融作用对黏聚力影响比较显著,随着冻融循环次数的增加,黏聚力逐渐减小,最大衰减幅度可达65%,而内摩擦角上下波动较大无明显趋势。此外,随着细砾组P_(2-5)含量的增加,剪切强度、弹性模量及抗剪强度指标均呈现不同程度的减小,这与粗粒土内部粗颗粒和细颗粒占比及其强度发挥机制有关。 相似文献
536.
Patricia Miretzky Carolina Muñoz Alejandro Carrillo-Chávez 《Environmental Chemistry Letters》2007,5(3):131-136
The Pb (II) adsorption/desorption mechanism onto a natural sandy loam soil was studied by batch experiments at different pHs
(3.0, 4.5, 6.0), at different ionic strength (0, 0.02 and 0.1 M) and with different electrolytes solutions of NaCl, NaAcO
and NaNO3. Pb was strongly adsorbed onto the soil due to the formation of a mix of inner-sphere and outer-sphere complexes. Experimental
adsorption data fitted Freundlich and Langmuir isotherms. The desorption results with 0.1 M Mg (NO3)2 and 0.1 M NaAcO solutions corroborated the mechanisms proposed. The strong binding of Pb (II) to high affinity sites on soil
minerals seems to be responsible for the extent of hysteresis. The sandy loam soil under study thus constitutes a natural
control for Pb contamination. 相似文献
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Julia Martínez-Blanco Pere Muñoz Assumpció Antón Joan Rieradevall 《Journal of Cleaner Production》2011,19(9-10):985-997
This study presents detailed and comprehensive inventories on the horticultural production of tomato using compost (CM) or mineral fertilizers (M), in both open-fields (OF) and greenhouses (GH), providing information on the environmental impacts and assessing the agronomic viability of the four cultivation options. Life cycle assessment (LCA) was used to calculate the potential environmental impacts of the tomato production cycle per ton of product. The stages in the assessment included: mineral and organic fertilizers production, fertilizers transport, cultivation stage and greenhouse stage. The data were obtained experimentally in pilot fields and in an industrial composting facility using municipal organic waste, both located in the Mediterranean area. The results indicate that replacing a fraction of the mineral fertilizers dosage with compost is a good option, as this did not alter yield or fruit size parameters. Greenhouse protection increased infrastructure materials requirements but enhanced harvest by almost 50% and reduced the water and pesticides requirement. Compost production and greenhouse stages were the most impacting stages. Without subtracting the avoided burdens by composting and not dumping organic waste, the cultivation option OF_M had the lowest and OF_CM the highest impact. When avoided burdens were taken into consideration, the environmental impacts of the four cultivation options varied, depending on the impact category, with bigger differences due to fertilization as a variable rather than the production system. 相似文献
540.
A. Vignes F. Muñoz J. Bouillard O. Dufaud L. Perrin A. Laurent D. Thomas 《Process Safety and Environmental Protection》2012,90(4):304-310
Previously, an extensive study has been carried out in order to assess the ignition sensitivity and explosivity of aluminum nanopowders. It showed notably that, as the particle size decreases, minimum ignition temperature and minimum ignition energy decrease, indicating higher potential inflammation. However, the explosion severity decreases for diameters lower than 1 μm. As a consequence, this study leads to the conclusions that the ignition sensitivity and explosion severity of aluminum nanopowders may be affected by various phenomena, as pre-ignition, agglomeration/aggregation degree and the intrinsic alumina content. The presence of wall-quenching effects and the predominance of radiation compared to conduction in the flame propagation process have to be discussed to ensure the validity of the 20 L sphere and of the results extrapolation. Based on the peculiar behaviours that had been previously highlighted, a specific risk analysis has been developed in order to assess the fire and explosion risks of such materials. It has been applied to an industrial plant of aluminum nanopowders production. The hazard identification and the consequence modelling steps, especially the quantification of the likelihood and consequences, have been designed specifically. The application of this method has led to the definition of the most adequate safety barriers. 相似文献