K2 C2 O4-KCl法快速测定石灰性紫色土壤阳离子交换量

用K2C2O4-KCl混合液作为交换剂,K+作为指示性阳离子,C2O42-抑制土壤中碳酸盐的溶解,采用火焰光度法测定交换后溶液中K+浓度的减少量可计算出石灰性紫色土壤的阳离子交换量.经理论计算及试验比较,K2C2O4,KCl浓度以0.03,0.02 mol/L为宜;交换剂pH、振荡时间分别为8.5,20 min的处理得出的结果与NH4Cl-(NH4)2C2O4标准方法比较回收率可达90%以上;经7次重复,变异系数＜6%;结果表明该方法具有较好准确性及重复性,可以作为1种速测方法.

DETERMINATION OF CATION EXCHANGE CAPACITY IN CALCAREOUS PURPLE SOIL WITH THE K2C2O4-KC1 DOUBLE-QUICK EXCHANGE METHOD

In this experiment,the admixture of K_2C_2O_4-KCl was used as the exchange reagent,K~+ as the indicatory ion and C_2O_4 was used to restrain carbonate from dissolving in the soil.CEC(cation exchange capacity) in a calcareous purple soil was calculated by determining K~+ loss after cation exchange through flame photometric analysis.The concentration of 0.03 and 0.02 mol/L is recommended for K_2C_2O_4 and KCl,respectively.Optimum results were achieved when pH was set at 8.5 and oscillation was kept for 20 min,in which case the recovery rate was over 90%.C.V.was less than 6% in 7 replicates.These results suggest that this method can be used as a CEC double-quick determination method.