摘要
Mehlich法和电位滴定法研究表明 ,供试土壤胶体可变电荷量占总电荷量 (CECv/ CEC8.2 )的比例为33.6 4%～ 35 .5 8%;表面电荷量 CEC8.2 ,CECp 和 CECv 的大小次序为土娄土 >黄绵土 >黑垆土 >黄褐土 ;电荷零点(PZC)大小与此顺序相反 ;同一土壤胶体其 PZC大小呈 Ca(NO3 ) 2 >KCl>Na NO3 的趋势 ,在 Na2 SO4介质中不存在 PZC。各土壤胶体负电荷密度随 p H增加的幅度即为 p H对土壤胶体表面电荷密度的贡献率 (简称为 p H贡献率 ) ,增加的幅度愈大 ,表明 p H对表面负电荷密度的贡献率愈大。 p H贡献率的大小呈黄绵土 >黑垆土 >土娄土 >黄褐土的趋势 ;同一土壤胶体 ,p H的贡献率基本上呈现 KCl>Na2 SO4>Ca(NO3 ) 2 >Na NO3 。
Mehlich and potentiometric titration methods showed that specific value of varible negative charge to total negative charge (CEC v/CEC 8.2 ) was between 33.64% to 35.58%,the sequence of CEC 8.2 ,CEC p and CEC v was:old manured loessal soil>yellow loessal soil>dark cultivated loessal soil>yellow cinamon soil,the sequence of PZC was opposition with negative charge.In different eletrolytes,PZC of same soil colloid showed the trend of Ca(NO 3) 2>KCl>NaNO 3.The increasing slope of negative charge density with pH increasing was expressed with the pH contribution rate,the pH contribution rate of different soil colloids showed in the sequence that yellow loessal soil>dark cultivated loessal soil>old manured loessal soil>yellow cinamon soil,in different eletrolytes,pH contribution rate of same soil colloid showed the trend of KCl>Na 2SO 4>Ca(NO 3) 2>NaNO 3.
出处
《西北农林科技大学学报（自然科学版）》
CSCD
北大核心
2002年第1期47-51,共5页
Journal of Northwest A&F University(Natural Science Edition)
关键词
恒电荷土壤胶体
电荷零点
电位滴定
电荷密度
constant charge soil colloid
the point of zero charge
potentiometric titration
charge density
