蜈蚣草/桑树间作模式下的根际砷活化与吸收机制

The health risks posed by soil arsenic (As) contamination have received increasing attention. Phytoextraction using As hyperaccumulator Pteris vittata has been given specific focus. Intercropping of P. vittata and economical crops is now being widely promoted in slightly or moderately As contaminated farmlands. However, the process of As mobilization and absorption in the intercropping system is not clear yet. This study conducts pot experiments to study the As uptake by the intercropping system of P. vittata and mulberry tree. Based on the assumption that hyperaccumulator P. vittata can mobilize As in rhizophere and that P. vittata and mulberry tree have different tendencies to approach As,Synchrotron Radiation X-ray Absorption Spectrum and X-ray Phase Contrast Imaging are utilized to disclosed the As species and root architecture in the rhizophere. The impacts of intercropping system on the transfer and transportation process of As from soil to plant in the rhizophere of the intercropping system are to be elucidated. Results will be instructive for the optimization of phytoremediation technology using intercropping system.

土壤砷对人体健康的威胁已引起广泛关注。利用超富集植物蜈蚣草萃取土壤中的砷是当前土壤修复领域的关注重点。蜈蚣草和经济作物桑树的间作是中、低浓度砷污染农田治理中大力推广的植物修复措施之一，但目前蜈蚣草和桑树的间作对植物吸收砷的影响机制尚不明确。本研究拟采用一系列温室盆栽实验，揭示蜈蚣草和桑树在单作、间作时的砷吸收差异，并基于蜈蚣草对砷具有根际活化作用、桑树和蜈蚣草根系形态对砷具有不同响应特征的假设，采用同步辐射X射线吸收光谱和根系成像技术原位研究蜈蚣草/桑树间作模式下的砷活性和根系形态的动态变化，揭示间作模式对土壤-植物中砷的迁移转化规律的影响机制，为优化超富集植物/经济作物间作修复技术提供理论依据。

土壤砷对人体健康的威胁已引起广泛关注。利用超富集植物蜈蚣草萃取土壤中的砷是当前土壤修复领域的关注重点。超富集植物蜈蚣草和经济作物桑树的间作是中、低浓度砷污染农田治理中大力推广的土壤安全利用措施之一，但目前蜈蚣草和桑树的间作对植物吸收砷的影响机制尚不明确。本项目从植物修复技术推广应用中发现的问题出发，针对超富集植物/经济作物间作系统中目前尚未明确的“土壤-重金属-根系”三者之间的关系，以砷超富集植物蜈蚣草和经济作物桑树为研究对象，采用一系列温室盆栽实验，进行了以下研究：.（1）揭示间作模式对植物吸收砷的影响，发现蜈蚣草和桑树的间作能有效降低桑树对砷吸收，并促进蜈蚣草对砷的吸收；.（2）揭示了蜈蚣草和桑树在单作、间作时的砷吸收差异，以及间作模式对土壤-植物中砷的迁移转化规律的影响机制；.从土壤中的砷活化和根系形态对砷的响应特征阐明间作模式影响植物吸收砷的机制，间作模式下，蜈蚣草根系能够向桑树根际延伸，从而进行更有效的砷富集，降低砷在桑树根际的可利用性，达到增加蜈蚣草砷富集并降低桑树砷富集的目的。.砷超富集植物蜈蚣草/经济作物桑树间作能够实现土壤中砷的去除和桑叶的安全生产，是一种具有推广潜力的间作修复模式，但间作的关键参数优化还有待进一步研究。