有机酸对滇水金凤根际和非根际土壤酶活性及重金属解吸的影响

Effects of Organic Acids on Enzyme Activities and Heavy Metal Desorption in Rhizosphere and Non-rhizosphere Soil of Impatiens uliginosa Franch.

    摘要
  • 摘要:
    目的 探究外源有机酸对滇水金凤根际和非根际土壤中重金属解吸量和酶活性的影响，为滇池重金属污染修复提供理论依据。
    方法 模拟滇水金凤根系分泌物，研究不同浓度（0、0.005、0.01、0.05、0.1 mol L−1）的乙酸、丙酸、丁酸、戊酸、酒石酸对滇水金凤根际和非根际土壤铅（Pb）、铜（Cu）、锌（Zn）解吸量和酶活性的影响。
    结果 5种有机酸均能显著促进土壤中Cu和Zn的解吸，且随有机酸浓度增加其解吸量增大，根际土壤中重金属解吸量大于非根际土壤。根际土壤中以0.1 mol L−1丁酸对Pb、0.1 mol L−1酒石酸对Cu和Zn的解吸量最大，分别为19.41、22.40和22.97 mg kg−1。Cu和Zn的解吸分配系数（Kd）随5种有机酸浓度的增加而降低，Kd均在纯水处理时达最大值，分别为360.79和6592.64 L kg−1；非根际土壤中仅0.1 mol L−1丙酸能解吸Pb，乙酸浓度为0.005、0 mol L−1时Cu、Zn的Kd最大，分别为11079.68、3452.75 L kg−1。5种有机酸处理均能显著提高滇水金凤根际和非根际土壤中α-葡萄糖苷酶、β-葡萄糖苷酶、纤维二糖酶、木糖苷酶、乙酰氨基葡萄糖苷酶、亮氨酸氨基肽酶和磷酸酶活性，以0.1 mol L−1戊酸、酒石酸分别处理根际和非根际土壤磷酸酶活性最高，分别为1181.88 ± 2.54和717.34 ± 6.64 nmol h−1 g−1。土壤酶活性与有机酸浓度、Cu和Zn解吸量呈极显著正相关（P < 0.01），有机酸处理下滇水金凤根际土壤酶活性高于非根际土壤。
    结论 有机酸处理能增加滇水金凤根际和非根际土壤中Pb、Cu、Zn的解吸量和土壤酶活性，解吸后的重金属Cu、Zn能激活土壤酶活性。

     

    Abstract:
    Objective The objective of this study was to investigate the effects of exogenous organic acids on heavy metal desorption and enzymatic activities in the rhizosphere and non-rhizosphere soils of Impatiens uliginosa, and provide a theoretical basis for the remediation of heavy metal pollution in Dianchi Lake.
    Method By simulating the root exudates of Impatiens uliginosa, the effects of acetic acid, propionic acid, butyric acid, valproic acid and tartaric acid with different concentrations (0, 0.005, 0.01, 0.05, 0.1 mol L−1) on the desorption of Pb, Cu and Zn and enzyme activities in rhizosphere and non-rhizosphere soils were studied.
    Result The results showed that five organic acids significantly promoted the desorption of Cu and Zn. As the concentration of exogenous organic acids increased, the desorption of heavy metals in rhizosphere soil was higher than that in non-rhizosphere soil. In rhizosphere soil, butyric acid at a concentration of 0.1 mol L−1 had the highest desorption of Pb, tartaric acid at a concentration of 0.1 mol L−1 had the highest desorption capacity for Cu and Zn, which were 19.41, 22.40 and 22.97 mg kg−1 respectively. The desorption partition coefficient (Kd) of Cu and Zn decreased with the increasing of the concentration of five organic acids, and reached the maximum under pure water treatment, which were 360.79 and 6592.64 L kg−1 respectively. In non-rhizosphere soil, only propionic acid at a concentration of 0.1 mol L−1 could desorb Pb, and when the concentration of acetic acid was 0.005 and 0 mol L−1, the maximum Kd of Cu and Zn were 11079.68 and 3452.75 L kg−1 respectively. The activities of α-glucosidase, β-glucosidase, Cellobiohydrolase, Xylosidase, Acetylglucosaminidase, L-leucine aminopeptidase and phosphatase in rhizosphere and non-rhizosphere soil increased significantly under different treatments, the phosphatase activity in rhizosphere and non-rhizosphere soil treated with valproic acid and tartaric acid at a concentration of 0.1 mol L−1 was the highest, which were 1181.88 ± 2.54 and 717.34 ± 6.64 nmol h−1 g−1 respectively. Soil enzyme activity was extremely positive correlated with the concentration of organic acids and desorption quantity of Cu, Zn(P < 0.01), and the enzyme activity of rhizosphere soil was higher than that of non-rhizosphere soil under organic acid treatment.
    Conclusion Soil enzyme activities and the desorption of Pb, Cu, Zn in rhizosphere and non-rhizosphere soil could increase under organic acid treatments, and Cu, Zn that be desorbed from soils could activate soil enzyme activities.

     

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