柠檬酸和草酸对茶园土壤铅生物有效形态的影响

The Effect of Citric Acid and Oxalic Acid on Bioavailability of Lead in Soils of Tea Garden

为了探讨柠檬酸和草酸对茶园土壤中铅的化学形态的影响,采集无污染茶园土壤,喷施180mg/kg的硝酸铅,平衡后再添加不同浓度的柠檬酸或者草酸,分析土壤中水溶性铅和交换态铅含量的变化。结果表明,一定浓度的柠檬酸或者草酸对于土壤中水溶态铅和交换态铅的含量有降低作用,其效果与酸的类型和浓度有关。草酸对于土壤中有效性形态铅的降低作用优于柠檬酸,输入酸对于水溶态铅的降低作用强于对交换态铅的降低。当酸浓度达到0.2mmol/kg时,其降低作用最佳,之后随着输入酸浓度的升高,反而会增加土壤中有效性形态铅的含量。

To explore the effect of citric acid and oxalic acid on bioavailability of lead in soils of tea garden, unpolluted tea garden soil was collected and sprayed lead nitrate of 180 mg/kg. After the soil was balanced, different concentrations of citric acid or oxalic acid were added to the soil and 2 kinds of chemical states of lead in soil were analyzed. The results showed that a certain concentration of citric acid or oxalic acid would reduce the content of water-soluble and exchangeable lead and the effect was associated with the type of acid and its concentration. Oxalic acid had a better effect of reducing bioavailability of lead than citric acid. Imported acid had a more significant effect of reducing watersoluble lead than exchangeable form, with the best effect of acid concentration of 0.2mmol/kg. Afterwards, with the increasing of the imported acid concentration in the soil, the content of bioavailability of lead would increase.