可溶性无机盐对土壤中镉形态分布及生物可利用性的影响

Influences of Inorganic Salts on Cadmium Forms and Biological Availability in Alkaline Soil

针对碱性土壤中镉污染现象,通过实验分析碱性土壤中可溶性无机盐对镉形态分布和转化影响以及生物可利用性的影响,探索受污土壤自然修复方法。结果表明,可溶态Cd进入土壤后,转化成以残渣态为主,随着土壤中Cd的含量的增加,Cd的有效态含量增高。对于Cd的有效态,氯化物KCl、CaCl2的存在,增加了Cd的有效态的含量,随着浓度的增加Cd有效态含量增加,增加量为7%～122%。KH2PO4的存在,反而引起Cd的有效态含量减少,减少量为20%～46%。K2CO3的加入,使土壤中Cd的有效态含量减少,为5%～22%。对于Cd的碳酸盐态,KCl、CaCl2、KH2PO4的存在,均引起Cd的碳酸盐态的降低,降低量为2%～60%;K2CO3的存在,引起Cd的碳酸盐态的增加,增加量为12%～64%。对于Cd的铁锰氧化态,KCl、CaCl2、KH2PO4、K2CO3的存在,均引起Cd的铁锰氧化态的增高,增加量为20%～150%。对于Cd的有机结合态,CaCl2、KH2PO4、K2CO3的存在,均引起Cd的有机结合态的增高,增加量3%～73%。对于KCl,低浓度KCl引起Cd的有机结合态的减少,而高浓度KCl引起Cd的有机结合态的增加。可溶性无机盐对镉形态分布和转化影响在作物中能够显示出来:KCl的加入,使蔬菜对土壤中镉的吸收量增加了11%～22%;当加入KH2PO4时,蔬菜对镉的吸收量减少了17%～53%。植物中Cd的含量变化与无机盐进入土壤后Cd的形态变化规律特别是Cd的有效态的变化规律一致。

Four soluble inorganic salts were used to study their influences upon cadmium forms in the alkaline soil and contents of cadmium absorbed by plants in the experiment. All the four salts were able to influence the forms of cadmium in the salt-alkaline soil. Chloride KCl and CaCl2 added into the soils could increase the contents of available cadmium in the soils by 7%-122%, and the higher the salt concentration added into the soils was, the higher the contents of available cadmium were. KH2PO4 and K2CO3 added in the soils could decrease the contents of available cadmium by 20%-46%. KCl, CaCl2 and KH2PO4 added into the soils could decrease the contents of carbonate form of cadmium in the soils by 12%-60%, but K2CO3 could increase the contents of carbonate form of cadmium by 12%-64%. KCl, CaCl2, KH2PO4, K2CO3 added into the soils could increase the contents of Fe-Mn oxidation form of cadmium by 20%-150%. CaCl2, KH2PO4, K2CO3 added into the soils could increase the contents of cadmium of organic combination form in the soils by 3%-73%. The influence of KCl added into the soils upon the organic combination form of cadmium was complex. When the lower concentration of KCl solution added into the soils, the contents of cadmium of organic combination form decreased, while the higher KCl concentration increased the contents of organic combination form cadmium. The influences upon cadmium forms by soluble inorganic salts could be shown by the contents of cadmium in plant bodies. After KCl was added into the soil, the contents of cadmium in vegetables such as spinach, celery and carrot could increase 11%-22%, while the contents of cadmium in vegetables could decrease 17%-53% with KH2PO4 added.