秋枫的铅镉复合污染胁迫耐受性及富集转移能力研究

Study on Tolerance and Enrichment and Transfer Ability of Pb and Cd Combined Pollution Stress in Bischofia javanica

【目的】利用植物,特别是乔木树种修复治理铅镉等重金属污染土壤成为我国生态环境治理的热点问题之一。与灌木和草本相比,多年生的乔木树种吸收量大、耐受性强、成材率高、综合人工成本低,更加适合于铅镉等重金属污染修复。秋枫是常见的景观树种,能够吸收和抵抗二氧化硫等污染气体,对周围环境起到一定的净化作用。本研究旨在了解秋枫对铅镉复合污染胁迫的耐受性和富集转移能力。【方法】选用乔木秋枫的1年生幼苗,通过使用氯化镉和乙酸铅模拟外源性铅镉土壤污染并制作不同浓度正交复合试验,用水培和盆栽两种方法培育秋枫幼苗,分时段测量植物各部分铅镉含量,研究秋枫对铅镉两种重金属的吸收情况,铅镉复合污染对秋枫株高和生物量累积的影响情况,以及铅镉富集转移到秋枫地上部分情况。【结果】在铅镉复合污染条件下秋枫幼苗鲜重增量明显低于对照组,且污染浓度越高鲜重增量下降量越大;当铅镉复合溶液的浓度较低时,秋枫的生长速度变快,而当铅镉复合溶液的浓度较高时,秋枫的生长变慢。镉浓度相同的条件下,秋枫幼苗各试验分组根部铅含量与土壤铅浓度的变化正相关,随土壤铅浓度变大而增加;在铅浓度相同的条件下,秋枫根部和地上部分铅含量与土壤镉浓度呈正相关,随镉浓度增加而升高。【结论】秋枫的生长从株高的表现来看呈现出“低促高抑”现象,低浓度的铅镉复合污染对秋枫的生长产生一定的促进作用,而高浓度的铅镉复合污染则显著抑制秋枫的生长,证明秋枫对铅镉复合污染胁迫具有一定的耐受性,适合在低浓度铅镉复合污染土壤中栽植。铅和镉具有交互作用,在土壤中存在轻度外源镉污染的条件下,对秋枫吸收积累铅具有一定的促进作用,能够加大对铅的吸收和富集转移能力;而轻度外源铅污染能够促进秋枫根部以及地上部分对镉的吸收累积和向秋枫地上部分富集转移。

【Objective】The use of plants,especially tree species,to remediate and control heavy metal contaminated soil such as lead and cadmium has become one of the hot issues in ecological environment management in China.Compared with shrubs and herbs,perennial tree species have higher absorption capacity,stronger tolerance,higher yield,and lower comprehensive labor costs,making them more suitable for the remediation of heavy metal pollution such as lead and cadmium.Bischofia javanica is a common landscape tree species,which can absorb and resist sulfur dioxide and other pollutants and play a certain purification role in the surrounding environment.In order to understand the tolerance and enrichment and transfer ability of Bischofia javanica to lead cadmium combined pollution stress.【Method】1-year old seedlings of Bischofia javanica were selected to simulate exogenous lead-cadmium soil pollution by using cadmium chloride and lead acetate,and orthogonal composite tests with different concentrations were carried out,Bischofia javanica seedlings were cultivated by hydroponics and pot planting.The lead and cadmium contents in various parts of the plant were measured in different periods to study the absorption of the two heavy metals of Bischofia javanica,the effects of lead and cadmium combined pollution on the plant height and biomass accumulation of Bischofia javanica,and the enrichment and transfer of lead and cadmium to the aboveground parts of Bischofia javanica.【Result】The study found that under the conditions of lead and cadmium combined pollution,the fresh weight increment of Bischofia javanica seedlings was significantly lower than the control group,and the higher the pollution concentration,the greater the decrease in fresh weight increment.When the concentration of lead cadmium composite solution is low,the growth rate of Bischofia javanica becomes faster,while when the concentration of lead cadmium composite solution is high,the growth of Bischofia javanica becomes slower.Under the same cadmium concentration,the root lead content of Bischofia javanica seedlings in each experimental group was positively correlated with the changes in soil lead concentration,which increased with the increase of soil lead concentration.Under the same lead concentration conditions,the lead content in the roots and aboveground parts of Bischofia javanica is positively correlated with soil cadmium concentration,and increases with the increase of cadmium concentration.【Conclusion】The growth of Bischofia javanica shows a phenomenon of“low promotion and high inhibition”from the perspective of plant height.Low concentrations of lead and cadmium combined pollution have a certain promoting effect on the growth of Bischofia javanica,while high concentrations of lead and cadmium combined pollution significantly inhibit the growth of Bischofia javanica,proving that Bischofia javanica has a certain tolerance to lead and cadmium combined pollution stress and is suitable for planting in low concentrations of lead and cadmium combined pollution soil.Lead and cadmium have an interactive effect.In the presence of mild exogenous cadmium pollution in the soil,it has a certain promoting effect on the absorption and accumulation of lead by Bischofia javanica,which can increase the ability to absorb,accumulate,and transfer lead.However,light exogenous lead pollution can promote the absorption,accumulation and transfer of cadmium from roots and aerial parts to aerial parts of Bischofia javanica.