AMF对山原红壤镉污染流形成与淋溶特征的影响及机理

The cadmium (Cd) contaminated flows from heavy metals polluted soils are an important form for Cd diffusion from soils to the environment. Arbuscular mycorrhizal fungi (AMF), which can form a symbiosis relationship with the most terrestrial plants, are a kind of soil microorganisms widely existing in the nature. There is a huge and dense hyphae network of AMF in soils. The mycorrhizal hyphae have a remarkable effect on soil physicochemical properties, Cd speciation and its transfer in the soil-plant system. However, whether AMF affect the formation and leaching characteristics of Cd contaminated flows in soils is still not known. In this project, the mountain red soil polluted by Cd at different levels around a lead and zinc mine in Yunnan Province are selected as the studying materials. We will carry out some experiments including a field plot, a pot cultivation in a net isolated compartment, adsorption and desorption, and soil column leaching. The research aims include: (1) To clarify the effects of AMF on the formation and leaching characteristics of Cd contaminated flows in the mountain red soil. (2) To clarify the effects of AMF on the chemical properties of the soil particles with different sizes and the interflows in soils, flowing the main research idea of “AMF - chemical properties of soil particles and interflows - Cd adsorption and desorption”. (3) To expound the relationship between the chemical properties of soil particle surface and Cd adsorption, and between the chemical properties of interflows and Cd desorption from soil particles. (4) To reveal the mechanisms of AMF on the formation and leaching characteristics of Cd contaminated flows from the polluted mountain red soil by altering the chemical properties of soil particles and interflows. The results will provide a new understanding on the supergene geochemistry of soil Cd and the affecting mechanisms of soil organisms on Cd contaminated flows in polluted soils, and therefore enrich both the theories of the soil pollution ecology and the mycorrhizal biology.

源自污染土壤的镉（Cd）污染流，是Cd环境扩散的重要方式之一。丛枝菌根真菌（AMF）是自然界广泛存在的一类土壤微生物，能与绝大多数的植物形成共生，在土壤中存在庞大密集的菌丝网络，显著影响土壤理化性质、Cd形态及其在土壤-植物系统中的迁移，但AMF是否影响土壤Cd污染流的形成与淋溶特征，还不清楚。项目选择云南铅锌矿区Cd污染的山原红壤，开展田间小区、分室隔网培养、吸附解吸、土柱淋溶等试验，明确AMF对山原红壤Cd污染流形成与淋溶特征的影响；以“AMF—水土介质化学性质—Cd吸附解吸”为主线，深入研究AMF对不同粒径土壤颗粒和壤中流化学性质的影响，解析土壤颗粒表面化学性质与Cd吸附、壤中流化学性质与土壤Cd解吸的关系，揭示AMF改变水土介质化学性质、影响山原红壤Cd污染流形成与淋溶特征的机理。研究结果为土壤Cd的表生地球化学、土壤生物的影响与机制提供新认识，丰富土壤污染生态与菌根生物学的理论。

源自污染土壤的镉（Cd）污染流，是Cd环境扩散的重要形式之一。丛枝菌根真菌（AMF）是自然界广泛存在的一类土壤微生物，能与绝大多数的植物形成共生，在土壤中存在庞大密集的菌丝网络，显著影响土壤理化性质、Cd形态及其在土壤-植物系统中的迁移，但AMF影响土壤Cd污染流的形成与淋溶特征尚不清楚。项目选择云南铅锌矿区Cd污染的山原红壤，开展分室隔网培养、土柱与砂柱培养及淋溶、田间小区等试验，以“AMF—水土介质化学性质—Cd流失”为主线，研究AMF改变水土介质化学性质、影响山原红壤Cd污染流形成与淋溶的特征及机理。结果表明：（1）施用苯菌灵抑制土著AMF的大田试验表明，抑制农田土著AMF导致农田地表径流溶解态和颗粒态镉浓度与流失量增加，提高20 cm和40 cm深度土层壤中流溶解态镉浓度，增加0-20 cm土层溶解态镉的淋溶流失，间接表明土著AMF具有减少农田地表径流与壤中流Cd流失的作用。（2）双室隔网培养、土柱盆栽及淋溶试验表明，AMF增加土壤球囊霉素相关蛋白（GRSP）含量与大团聚体比例，增加团聚体的比表面积和孔体积，增强土壤颗粒的Cd吸附能力；改变土壤溶液的性质，增加壤中流和淋溶液的pH、COD和NO-3含量，导致壤中流和淋溶液中CdOH+和FA2-Cd(6)(aq)的占比上升，降低壤中流Cd浓度与污染土壤Cd的淋溶流失。（3）砂柱培养与淋溶试验表明， AMF增加砂柱GRSP含量，导致砂粒比表面积增加、Cd吸附能力增强，降低砂柱溶液离子态和胶体态Cd浓度，减少离子态和胶体态Cd的淋溶流失；并促进砂培玉米分泌草酸、琥珀酸、苹果酸、丙二酸等低分子量有机酸；外加低分子量有机酸、GRSP能减少砂柱和土柱Cd的淋溶流失。因此，AMF通过改变污染土壤水土介质性质，具有减少污染农田土壤Cd流失的生态功能，在污染土壤Cd流失中起着重要的调控作用。研究结果为土壤Cd的表生地球化学、土壤生物的影响与机制提供新认识，丰富环境地球化学与菌根生物学的理论。