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包膜控释和常用氮肥氮素淋溶特征及其对土水质量的影响 被引量:62
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作者 张庆利 张民 田维彬 《土壤与环境》 CSCD 2001年第2期98-103,共6页
大量施用氮素化肥所引起的氮素损失和环境污染正日益受到重视。通过土柱模拟氮素养分的淋洗试验,探讨包膜控释氮肥和常用氮肥的氮素淋失特点及其对土壤和地下水质量的影响。研究结果表明,不同氮肥施入土壤后氮素的淋失率有着显著的差... 大量施用氮素化肥所引起的氮素损失和环境污染正日益受到重视。通过土柱模拟氮素养分的淋洗试验,探讨包膜控释氮肥和常用氮肥的氮素淋失特点及其对土壤和地下水质量的影响。研究结果表明,不同氮肥施入土壤后氮素的淋失率有着显著的差异,其中硝酸钾中氮素淋失率最高,其次为尿素,硫酸铵和碳铵的氮素淋失量明显较小。然而控释氮肥因其控制释放的特点,在氮素释放的高峰期,其模拟淋失量较高,但如果在田间条件下此释放高峰期与作物吸肥高峰期相吻合,则会显著地降低其淋失率。除尿素外,被淋失的氮素均以硝态氮为主,尿素则以酰胺分子态被淋溶。大量速效化肥的施入会形成土壤中的肥料“微域点”,引起交换性 Ca2+、 Mg2+离子的淋失,从长远来看可引起土壤结构的破坏,而施用控释肥则很少形成这种“微域点”,有利于土壤结构和肥力的维持。不同氮肥处理淋洗后对土壤pH值和有效氮含量变化的影响差异较大,其中以控释肥对土壤pH值变化的影响较小。大多数氮肥处理在淋洗后,土壤中各层速效氮含量较淋洗前有所降低,然而两种控释氮肥处理的土壤表层却能持续保持较高的有效氮含量。 展开更多
关键词 包膜控释肥 氮肥 淋溶 土水质量
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Assessment of strength development in cement-admixed artificial organic soil with GX07 被引量:1
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作者 李雪刚 徐日庆 荣雪宁 《Journal of Central South University》 SCIE EI CAS 2012年第10期2999-3005,共7页
To explore the stabilization effect of stabilizing agent GX07 on treating organic soil and the influence of organic matter on the strength development of stabilized soil,artificial organic soil with various organic ma... To explore the stabilization effect of stabilizing agent GX07 on treating organic soil and the influence of organic matter on the strength development of stabilized soil,artificial organic soil with various organic matter content was obtained by adding different amounts of fulvic acid into non-organic clay,and then liquid-plastic limit tests were carried out on the artificial organic soil.Meanwhile,unconfined compressive strength(UCS) tests were performed on cement-only soil and composite stabilized soil,respectively.The test results indicate that the plastic limit of soil samples increases linearly,and the liquid limit increases exponentially as the organic matter content increases.The strength of stabilized soil is well correlated with the organic matter content,cement content,stabilizing agent content and curing time.When the organic matter content is 6%,as the cement content varies in the range of 10%-20%,the strength of cement-only soil increases from 88.5 to 280.8 kPa.Once 12.6% GX07 is added into the mix,the strength of stabilized soil is 4.93 times compared with that of cement-only soil.GX07 can obviously improve the strength of cemented-soil and has a good economic applicability.A strength model is proposed to predict strength development. 展开更多
关键词 stabilized soil unconfined compressive strength artificial organic soil stabilizing agent GX07 composite stabilized soil total cement/water ratio
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Diesel oil infiltration in soils with selected antecedent water content and bulk density
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作者 马艳飞 李永霞 +3 位作者 S.H.Anderson 郑西来 冯雪冬 高佩玲 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第8期1924-1930,共7页
The effects of soil texture, initial water content and bulk density on diesel oil infiltration in fine sand and silty clay loam materials were evaluated. Three physical and two empirical equations express diesel oil i... The effects of soil texture, initial water content and bulk density on diesel oil infiltration in fine sand and silty clay loam materials were evaluated. Three physical and two empirical equations express diesel oil infiltration through soils with time, with coefficients of determination greater than 0.99. Diesel oil infiltrates more quickly in the fine sand than in the silty clay loam material. Diesel oil infiltration rates are found to decrease with increasing initial water content and bulk density for the silty clay loam material. The infiltration rate of diesel oil in the fine sand material increases slightly with increasing initial water content. The diesel oil saturated conductivity(Kdiesel) decreases with increasing bulk density for the silty clay loam column. Diesel oil sorptivity(S) decreases linearly with increased initial water content and bulk density of the silty clay loam material. Changes in empirical parameters relative to initial water content and bulk density are similar to the parameter S. 展开更多
关键词 INFILTRATION diesel oil SOIL physical and empirical models initial water content bulk density
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A study on Cr(Ⅵ)reduction from aqueous solutions by bauxite
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作者 M.D.TURAN H.S.ALTUNDOGAN 《Journal of Central South University》 SCIE EI CAS 2014年第5期1961-1967,共7页
The reduction of Cr(Ⅵ) in aqueous solution by using bauxite ore was investigated.Experimental results for Cr(Ⅵ)reduction in aqueous solution depending on some factors such as time,sulfuric acid amount,bauxite do... The reduction of Cr(Ⅵ) in aqueous solution by using bauxite ore was investigated.Experimental results for Cr(Ⅵ)reduction in aqueous solution depending on some factors such as time,sulfuric acid amount,bauxite dosage,initial Cr(Ⅵ)concentration,formic acid concentration,daylight and temperature were presented.The obtained results show that sulfuric acid amount,bauxite dosage and initial Cr(Ⅵ) concentration of solution are most effective parameters on the reduction process.Also,it has been found that the 60 g/L of bauxite dosage is sufficient to reduce up to 100% of Cr(Ⅵ) from acidic solution under the condition of low initial Cr(Ⅵ) mass concentrations such as 10 mg/L.The reduction reaction is completed within 30 min at 25 ℃ under the experimental conditions:bauxite dosage of 60 g/L,amount of sulfuric acid 40-60 stoichiometric and initial mass concentration of Cr(Ⅵ),10 mg/L.It was determined that reduction percentage is decreasing with increasing initial Cr(Ⅵ) concentration.The chemical oxygen demand of bauxite ore was found to be 26 mg COD/g. 展开更多
关键词 bauxite ore CHROMIUM REDUCTION sulfitric acid
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