盐角草在Cd、Pb、Li污染盐土修复中的应用潜力

Application potential of Salicornia europaea in remediation of Cd, Pb and Li contaminated saline soil

摘要:

滩涂和内陆盐碱地是重要的后备土地资源。近年来镉 (Cd)、铅 (Pb) 等土壤重金属和锂 (Li) 污染对盐碱地开发利用和生产安全造成严重威胁。利用盐生植物修复污染盐土是最经济有效的方法。本研究以盐生植物盐角草Salicornia europaea L.为材料，采用盆栽方式，通过比较分析盐角草在不同浓度Cd (0?50 mmol/L)、Pb (0?50 mmol/L)和Li (0?400 mmol/L) 处理下的生长和生理生化指标及离子含量的变化，研究盐角草对3种金属污染物胁迫的耐性及积累特性，以期探讨盐角草在Cd、Pb、Li污染盐土修复中的应用潜力。结果显示，随着Cd、Pb处理浓度升高，盐角草的株高、鲜重和干重均显著下降。低浓度Li (≤20 mmol/L)处理促进盐角草的生长，而高浓度Li (≥20 mmol/L) 处理则抑制植物生长。盐角草对Cd、Pb、Li的耐受性顺序为Li>Pb>Cd。Cd、Pb、Li胁迫可能降低了盐角草对Na和K的吸收与转运而影响植株的生长。另一方面，盐角草抗氧化酶系统对Cd、Pb、Li胁迫表现出不同的响应机理，多种抗氧化物酶协同作用，抵制Cd、Pb、Li胁迫造成的氧化毒害。盐角草根和地上部分Cd、Pb、Li含量随着处理浓度的升高而增加，其中Cd和Pb的分布特征为根＞地上部分，Li的分布特征为地上部分>根。研究结果表明盐角草对Cd、Pb、Li的胁迫均具有较强的耐受性与自我调节能力，且具有富锂特性，具备修复Cd、Pb、Li污染盐土的潜力。本研究为深入研究盐角草耐受Cd、Pb、Li胁迫的机制奠定了基础，揭示了利用盐角草修复高盐碱土壤中Cd、Pb、Li污染的应用潜力。

Abstract:

Coastal and inland saline-alkali soil is important reserve land resources. However, some parts of saline land are now under the threat of heavy metals such as cadmium (Cd), lead (Pb) and the light metal lithium (Li). Phytoremediation with halophytes could be the most economical and effective way to restore the contaminated saline soil. In this study, the growth, physiological and biochemical indexes and ion contents of halophyte Salicornia europaea under different concentrations of Cd (0?50 mmol/L), Pb (0?50 mmol/L) and Li (0?400 mmol/L) were investigated to evaluate the tolerance and accumulation of the metal contaminations. The results showed that plant height, fresh weight and dry weight of S. europaea decreased significantly with the increase of Cd and Pb concentration. Low concentration of Li (< 20 mmol/L) promoted the growth of S. europaea, while the growth of plants was inhibited under higher concentration of Li (> 20 mmol/L). The tolerance order of S. europaea to Cd, Pb and Li was Li > Pb > Cd. Cd, Pb and Li stresses may negatively affected Na and K uptake and transport in S. europaea to affect plant growth. In addition, the antioxidant enzyme system synergistically responsed to resist the oxidative toxicity of different ions. The contents of Cd, Pb, Li in roots and shoots of S. europaea also increased with the increase of treatment concentration. Furthermore, Cd and Pb contents in roots were significantly higher than in shoots, while more Li accumulated in shoots than in roots. The aforementioned results showed that S. europaea had strong tolerance along with a high accumulate ability to Cd, Pb and Li, indicating its application potential in restoring Cd, Pb and Li contaminated saline soil. This study laid a basis for further exploration of the tolerance mechanism of S. europaea to Cd, Pb and Li stresses, and gave a new perspective for the usage of S. europaea to remediate Cd, Pb and Li pollutants in high-salinity alkali soils.