Surface Chemical Properties of Colloids in Main Soils of China

Surface chemical properties of soil colloids are the important factor affecting soil fertility and genesis.To provide scientific basis for soil genetic classification,promotion of soil fertility and reasonable fertilizqation,the specific surface area and electric charge of soil colloids in relation to clay minerals and organic matter are further discussed on the basis of the results obtained from the studies on surface chemical properties of soil colloids in five main soils of China.Results from the studies show that the effect of clay minerals and organic matter on the surface chemical properties of soil colloids is very complicated because the siloxane surface,hydrated oxide surface and organic matter surface do not exist separately,but they are always mixed together and influenced each other.The understanding of the relationship among clay minerals,organic matter and surface chemical properties of soil colloids depends upon further study of the relevant disciplines of soil science,especially the study on the mechanisms of organo-mineral complexes.     

有机酸对恒电荷土壤表面电荷性质的影响

低分子量有机酸在土壤中随着各种有机物的分解和生物的生命活动不断形成、转化并累积,形成一些较高浓度的有机酸微区,影响养分的生物有效性和根际系统中的物质循环。随着根际化学的兴起, 根际土壤化学和元素行为越来越引起广大土壤科学工作者的关注。     

Types of Crystalline Iron Oxides and Phosphate Adsorption in Variable Charge Soils

The types,contents and morphologies of crystalline Fe oxides and their relations to phosphate adsorption on the clay fractions in soils with varable charge in southern China were investigated by means of XRD,TEM,EMA and chemical analysis methods.Results indicated that the types and contents of crystalline Fe oxides varied with the soils examined.The dominant crystaline Fe oxide was hematite in the latosols and goethites in the red soils.In yellow-brown soils,the only crystalline Fe oxide was goethite.The difference between Ald and Alo came mainly from the Al Substituting for Fe in the Fe oxides.The crystal morphology of goethite appeared mainly as subrounded flat or iso-dimensional rather than acicular particles,Hematities occurred in plates of various thickness,Their MCDa/MCDc ratios in the latosols and red soils were generally above 1.5 and below 1.5,respectively.The MCD values of goethites and hematites were 15-25nm and 20-35nm,and their specific surface areas were 80-120m^2/g and 35-75m^2/g,respectively.The goethite crystals were generally smaller,Variations of the total amounts of crystalline Fe oxides in clay fractions were not related to plhophats adsorption.The types,contents and morphologies of crystalline Fe oxides in the soils remarkably affected phosphate adsorption characteristics of the soils.The phosphate adsorption of goethite was much greater than that of hematite,The higher th MCDa/MCDc ratio of hematite,the lower the phosphate adsorption.     

外生菌根真菌Laccaria bicolor S238N增强花旗松生长及其对磷钾吸收的能力

Two variable charge soils were submerged after the addition of 30g/kg of organic matter to examine the differences in behavior between iron and manganese with respect to reduction and the distribution of different froms of the reduced elements.The reduction of manganese proceeded almost synchronously with the fall in redox potential,while the reduction of iron showed a remarkable lag behind the Eh change.Once formed,the distribution of water-soluble,exchangeable and precipitatied forms of ferrous iron was controlled by pH,CEC of the soil and total concentration of the element.For manganous ions,the proportions of water-soluble and exchangeable forms in total Mn^2 were larger than those for ferrous ions.The reduction of the two elements led to a mobilization of them,and such effect persisted even after drying of the soil,i.e.,the content of amorphous Fe became higher than that of the original soil.     

微波消解-恒pH滴定法快速测定粮食中的粗蛋白

为建立一种快速测定食品中粗蛋白质的新型分析方法,选择小麦为样品,用硫酸一过氧化氢混合溶液为消解剂,利用微波压力程序加热技术快速消解样品,用甲醛法将NH4 转化为H ,以KOH为标准溶液,用恒pH滴定法进行测定.结果表明:小麦干基粗蛋白的含量在14%～17%之间,RSD1.2%～2.1%(n=6或12).与经典方法对照测定,经F检验和t检验表明两者之间无显著性差异(置信度95%).该法操作简单、快速,试剂用量少,空白值低,工作效率大大提高,结果令人满意.     

新疆耐特菲姆昌恒现代灌溉农业系统有限公司建成投产

由以色列耐特菲姆公司和新疆生产建设兵团农七师130团场合资的耐菲姆昌恒现代灌溉农业统有限公司2004年3月28日在新疆奎屯市经济开发区建成投产.     

电解质浓度对土壤吸附铜离子时氢离子释放的影响

研究了不同铜离子浓度、不同电解质浓度情况下,吸附铜离子时氢离子释放对两种可变电荷土壤和4种恒电荷土壤悬液pH的影响。研究结果表明,除了黄棕壤外,含铁量越高,由于吸附铜离子后所引起的土壤ΔpH最大值越小。加入的铜离子浓度为10-4 mol L-1时,铜离子吸附对中和曲线形状没有根本影响。在较低浓度时,铜离子吸附时氢离子的释放较少;而在较高浓度时,当体系pH大于一临界值时,开始释放大量氢离子。氧化铁是引起恒电荷土壤和可变电荷土壤在吸附铜离子时氢离子释放差异产生的主要原因。电解质浓度的变化对恒电荷土壤和可变电荷土壤吸附铜离子后中和曲线变化影响有很大的区别,含铁量越高,电解质浓度对土壤吸附铜离子后的氢离子释放的影响越小。     

肉制品中脂肪氧化影响因素研究

肉中的脂肪氧化伴随着肉的整个成熟过程,脂肪的氧化对肉的产品品质造成双面影响,文章主要从影响水包油型乳浊液的几个方面:接触面的面积、接触面的相互作用、乳浊液电荷、接触面的厚度及接触面的通透性等几个影响脂肪氧化的因素,介绍了乳化液滴中抗氧化剂的作用及液滴中其他成分与脂肪氧化之间的关系,从而为生产中合理控制肉中脂肪氧化及寻找新的抗氧化剂、抗氧化技术提供依据。     

不同pH下两种可变电荷土壤中Cu(II)、Pb(II)和Cd(II)吸附与解吸的比较研究

对两种可变电荷土壤的研宄表明,土壤对Cu(Ⅱ)、Pb(Ⅱ)和Cd(Ⅱ)的吸附量均随pH的增加而增加,但Cu(Ⅱ)与Pb(Ⅱ)吸附量之间的差值随pH增加而减小,Cu(Ⅱ)和Pb(Ⅱ)与Cd(Ⅱ)吸附量之间的差值随pH增大呈增大趋势.土壤吸附的Cd(Ⅱ)的解吸量随吸附平衡液pH的增加而增加;但Cu(Ⅱ)和Pb(Ⅱ)的解吸量先随pH增加而增加,在某一pH时达最大,随后再逐渐减小.3种重金属离子在可变电荷土壤中吸附和解吸行为的不同特征是pH导致的土壤表面电荷的变化和离子水解程度的变化共同作用的结果.本文的研究结果对可变电荷土壤中重金属的控制和污染土壤的修复具有一定的指导意义.