潮土施镍对小白菜的生物效应及其临界值研究

研究潮土施Ni对盆栽蔬菜的生态效应,并通过小白菜生物量的变化、地上部茎叶Ni质量比及土壤有效态Ni质量比来表征土壤Ni污染的毒性临界值.结果表明,潮土施Ni对蔬菜未表现出增产效应.施Ni量低于25 mg/kg,其生物产量无明显降低.随施Ni量的增加,生物产量呈显著下降,生物量变化与Ni质量比呈高度负相关.潮土施Ni增加茎叶和根系中Fe,Mn,Ca,Mg元素质量比,降低Cu,Zn元素质量比.4种性质不同的提取试剂提取的土壤有效态Ni质量比与植物Ni吸收均呈高度正相关,较好地反映了植物的危害状况,且以DTPA提取效果最佳.以生物减产量突变点为依据,确定潮土施Ni毒害临界值为:土壤全量Ni为41.86 mg/kg,有效态Ni质量比为2.55mg/kg(DTPA)和茎叶Ni质量比为22.39 mg/kg.

Biological effects on Chinese cabbage and critical concentration of Ni application in the calcareous soil

The present article aims to introduce the authors' investigation and research of the biological effect of Ni application on the Chinese cabbage growth in the calcareous soil. It has also proved that the critical concentration of Ni content in the soil as a pollutant by the cabbage's biomass variation, its available amount of content in the stems and leaves as well as in the soil. The results show that no obvious advantage was found in the cabbage's biomass when Ni was applied in the calcareous soil. If Ni was applied lower then 25 mg/kg, the biomass of the cabbage would show a little decrease. However, when the amount of Ni applied to the soil increased, its biomass decreased significantly. Thus, it can be seen that there exists a negative relation between biomass. variation and Ni content. On the other hand, when the content of Fe, Mn, Ca and Mg in the stems, leaves and roots increased, its content of Cu and Zn would decrease with Ni applied to the soil. The experiment has thus proved that when the four different kinds of extracting solvents were used, high positive correlation was found to exist between the available Ni content in the soil and Ni absorbed by the plant. The phenomenon thus reflects its harm degree to the plant. Among all of the extracting solvents used in this experiment, DTPA gave the better extraction effect. Based on the biomass significant reduction, the critical concentration of Ni in the calcareous soil has thus been confirmed as follows: the content of Ni available and total in the soil were 2.55 mg/kg (DTPA) and 41.86 mg/kg respectively, and Ni in stems and leaves was 22.39 mg/kg.