摘要
In the present work, the exchangeable acidity of a red soilcolloid and a latosol colloid at different pH during reacting withfour neutral salts was measured. The results show that theexchangeable acidity increased with increasing amounts of the neutralsalts added, and the relation between them was almost linear. Whenthe amount of the neutral salt added was lower than a certain value,the slop of the line was high, and the slop turned low when theamount exceeded that value, so there was a turning point in eachline. The addition amounts of the neutral salts for the turningpoints were affected by the cation species of the neutral salts, butpH had less effect on them. After the turning points occurred, theexchangeable acidity of the red soil colloid still graduallyincreased with the addition amounts of the neutral salts, but that ofthe latosol colloid did not increase any more.
In the present work, the exchangeable acidity of a red soil colloid and a latosol colloid at different pH during reacting with four neutral salts was measured. The results show that the exchangeable acidity increased with increasing amounts of the neutral salts added, and the relation between them was almost linear. When the amount of the neutral salt added was lower than a certain value, the slope of the line was high, and the slope turned low when the amount exceeded that value, so there was a turning point in each line. The addition amounts of the neutral salts for the turning points were affected by the cation species of the neutral salts, but pH had less effect on them. After the turning points occurred, the exchangeable acidity of the red soil colloid still gradually increased with the addition amounts of the neutral salts, but that of the latosol colloid did not increase any more. The exchangeable acidity in NaClO4, KClO4 and NaCl solutions increased at first, and then decreased with increasing pH, that is to say, peak values appeared. The peak positions of the exchangeable acidity in relation to pH changed with neutral salt solutions and were affected by the surface characteristics of the soil colloids, but not affected by the amounts of the neutral salts added. The exchangeable acidity in the Ba(NO3)2 solution increased continuously with increasing pH. The exchangeable acidity of the red soil colloid was obviously larger than that of the latosol colloid.
基金
Project (Nos. 49971046 and 49831005) supported by the National Natural Science Foundation of China.
