根际-非根际土壤砷形态与三七根部砷赋存形态的相关性研究

本研究选取云南省典型砷污染土壤,以盆栽试验的方式,采用土壤砷形态分级连续浸提法和植物砷形态分级提取法,对三七生长的根际-非根际土壤中砷形态及三七中砷的赋存形态相关性进行研究。结果表明：(1)根际-非根际土壤中各砷形态含量由高到低的总体趋势为：残渣态＞结晶铁锰或铁铝水化氧化物结合态＞无定形和弱结晶铁铝或铁锰水化氧化物结合态＞专性吸附态＞非专性吸附态,残渣态所占比重最大,可达62%～86%。受根部活动的影响,非专性吸附态砷的含量均为根际土＞非根际土。(2)三七根部砷的赋存形态为F_r最高,含量为4.12mg/kg～7.60mg/kg。F_HAc和F_HCl虽迁移活性较弱但其所占的比例却不容忽视,最高可达25%。(3)根际-非根际土壤中不同砷形态与土壤总砷均呈正相关,其中残渣态R^₂=0.976。根际土中活性较强的非专性吸附态砷R^₂=0.499。(4)高砷土壤中砷形态与三七根部砷赋存形态间呈极显著相关,R^₂=0.992。中高砷土壤和中度砷土壤非根际土壤中的砷形态与三七根部砷赋存形态的相关系数较根际土有所升高,具有潜在砷毒害风险。

Study on the correlation between arsenic forms in rhizosphere and non-rhizosphere soils and arsenic occurrence forms in Panax notoginseng roots

Objective To explore the correlation between arsenic forms in rhizosphere and non-rhizosphere soils of Panax notoginseng and arsenic occurrence forms in Panax notoginseng roots. Methods The typical arsenic contaminated soil in Yunnan province was selected and studied by pot experiment, using soil arsenic form grading continuous extraction method and plant arsenic form grading extraction method. Results (1) The general trend of arsenic form content in rhizosphere and non-rhizosphere soils (GJ, KM) from high to low was: Residue form arsenic>crystalline iron manganese or iron aluminum hydrated oxide combined form arsenic>amorphous and weak crystalline iron aluminum or iron manganese hydrated oxide combined form arsenic>specific adsorption form arsenic>non-specific adsorption form arsenic. The proportion of residue form arsenic was the largest, up to 62.79%?86.10%. Affected by root activity, the content of non specific adsorbed arsenic was rhizosphere soil>non rhizosphere soil. (2) The occurrence form of arsenic in the root of Panax notoginseng was Fr, with the highest content of 2.14?7.60 mg/kg. Although the migration activity of FHAc and FHCl was weak, their proportion could not be ignored, up to 25.85%. (3) Different forms of arsenic in rhizosphere and non-rhizosphere soils were positively correlated with total arsenic in soil, in which residue form R2=0.976, P<0.01. The non specific adsorption form of arsenic with strong activity in rhizosphere soil R2=0.499, P<0.05. (4) There was a very significant correlation between arsenic forms in high arsenic soil and arsenic occurrence forms in Panax notoginseng roots, R2=0.992, P<0.001. Conclusion The correlation coefficient between arsenic forms in non rhizosphere soil and arsenic occurrence forms in Panax notoginseng root is higher than that in rhizosphere soil, which has potential arsenic toxicity risk.