Physiological and biochemical responses of Melissa officinalis L. to nickel stress and the protective role of salicylic acid

The present study investigated the mediatory effects of salicylic acid (SA) in alleviating nickel (Ni) toxicity in Melissa officinalis L. One-month-old plants were exposed to different levels of Ni and SA concentrations in sand culture under greenhouse conditions. Excess Ni significantly inhibited the growth indices and dramatically increased accumulation of Ni in the leaves and roots. Exogenously SA applications (1.0 mM) led to a substantial improvement in the shoot and root fresh and dry weights. Foliar application of SA mitigated the deleterious effects of Ni and decreased its transport to the shoots. The results showed a significant loss in chlorophylls and carotenoids contents only at 500 µM of Ni. The impact of SA was not significant in terms of chlorophyll contents, while carotenoid contents of the Ni-stressed plants were significantly affected by SA. Exposure to Ni did not modify proline accumulation. Hydrogen peroxide accumulation was observed under Ni stress, while lipid peroxidation significantly decreased at the same conditions. Application of SA caused a significant decrease in electrolyte leakage of Ni-stressed plants. Due to the high potential for Ni accumulation in the roots and translocation factor values lower than 1, M. officinalis could be introduced as an excluder medicinal plant.     

茶渣制备的生物质炭对重金属镍的吸附研究

为了寻找有效治理重金属镍污染的方法,明确茶渣基生物质炭的吸附能力和机理,本研究通过扫描电子显微镜(SEM)、激光粒度分析仪和Zeta电位对茶渣基生物质炭(TBC-700)进行表征及机理探究,用紫外分光光度计对吸附过程进行测定。结果表明：合成的TBC-700具有较疏松的孔状结构,其对镍的吸附过程更符合准二级动力学模型(R²>0.99)和Freundlich吸附等温线模型(R²>0.95)。TBC-700对镍的吸附存在多分子层吸附,去除率达42.91%,平衡时最大吸附量可达584.58 mg/g;TBC-700吸附重金属镍后在500 mg/L KH₂PO₄溶液中解吸率达62.33%,具有一定的循环吸附能力。