锗在土壤—茶树中的迁移富集特征及其影响因素

Migration and enrichment characteristics and its influencing factors ofgermanium in soil-tea system

在鄂西咸丰县茶园测量采集表层土壤样品1478件、土壤垂向剖面样品10组、茶叶和根系土样品130组,测试土壤中锗(Ge)、常量氧化物、有机碳(Corg)含量及pH值,以及茶树根、茎、叶中Ge及重金属含量等,研究土壤—茶树中Ge迁移转化规律及影响因素。结果表明,研究区茶园土壤Ge含量平均值为1.56 mg/kg,高于中国土壤Ge背景值(1.30 mg/kg);土壤Ge含量垂向分布总体表现为随深度增加而增加的趋势。茶树嫩叶Ge平均含量为5.56μg/kg,范围为1.76~28.00μg/kg,不同部位Ge含量和生物富集系数均为根>茎>老叶>嫩叶,转运系数表现为嫩叶>老叶>茎。相关分析表明,茶园土壤中,低pH和丰富的Corg有利于表层土壤Ge的富集(≤50 cm),对深层土壤(>50 cm)的影响相反;土壤Ge与SiO_(2)含量呈显著负相关,与Al_(2)O_(3)含量呈显著正相关,可能受黏土矿物吸附作用影响;弱风化淋溶和强脱硅富铝化程度有利于土壤Ge的富集。低pH值、强风化淋溶作用和弱脱硅富铝化程度有利于茶树对土壤Ge的吸收,茶树中各部位Ge的转移与As高度正相关。

A total of 1478 surface soil samples,10 groups of soil vertical profiles,130 groups of tea and root soil samples were collected from the tea garden in Xianfeng County,western Hubei Province.The contents of germanium(Ge),major oxides,organic carbon(Corg)and pH value in the soil,as well as the contents of Ge and heavy metals in the roots,stems and leaves of tea trees were measured to study the migration and transformation of Ge in soil-tea trees and its influencing factors.The results showed that the average Ge concentration in tea soil was 1.56 mg/kg,which was higher than the mean abundance of 1.30 mg/kg in China.The vertical distribution of soil content generally showed an increasing trend with the increase of depth.The average Ge content in tea was 5.56μg/kg and ranged from 1.76 to 28.00μg/kg.According to the Ge content and bioconcentration factor,different parts of tea plant were ranked as:roots>stems>old leaves>tender leaves,and translocation factor ranked as:tender leaves>old leaves>stems.The correlation analysis showed that low pH and abundant organic carbon were beneficial for the enrichment of Ge in surface soil(≤50 cm),but had the opposite effect on deep soil(>50 cm).There was a significant negative correlation between soil Ge and SiO_(2) content,and a significant positive correlation with Al_(2)O_(3) content,which may be affected by the adsorption of clay minerals.Weakly ba value of soil and strong desilicified allitization were beneficial for the Ge enrichment of soil.Low pH,strong ba value of soil,and weak desilicified allitization were beneficial for tea plant to absorb Ge of soil in tea garden.The transfer of Ge in various parts of tea plants was highly positively correlated with arsenic.