摘要
金属矿区及周边土壤重金属污染已成为影响环境和威胁人类健康的严重问题,继续寻找并研究生长快速的富集或超富集植物对污染土壤植物修复技术及生态环境的恢复都具有重要意义。本研究选取四川省雅安市汉源县富泉铅锌矿(FQ)及乌斯河铅锌矿(WS)的野茼蒿(Crassocephalum crepidioides (Benth.) S. Moore)为研究对象,在室内盆栽试验条件下研究了两地野茼蒿在不同重金属浓度梯度下的耐性及对镉、铅和锌的吸收富集特征,研究结果如下：
(1)在Cd胁迫下,野茼蒿表现出一定的耐性；随胁迫浓度的增高,镉富集能力逐渐增强。最高浓度处理下,株高、根长、生物量及叶绿素与对照相比都有显著下降(P<0.01)；叶片中过氧化物酶(POD)活性随处理浓度的增加而呈先增大后减小的趋势,超氧化物岐化酶(SOD)活性及过氧化氢酶(CAT)活性呈逐渐减小的趋势。Cd处理下,各个浓度镉含量均表现为细胞壁>细胞器>胞液；Cd在野茼蒿植物体内的含量呈随处理浓度的增加而升高的趋势,并在总体上表现为茎>叶>根；地上部最大含量达到1289.48 mg kg-1,植物体内的累积量最高达到1.24 mg株-1；各个处理下迁移系数和富集系数均大于1。
(2)在Pb胁迫下,两地野茼蒿耐性存在差异而富集能力均随胁迫浓度的增高逐渐增强。富泉铅锌矿野茼蒿的根长及株高均随着处理浓度的升高而逐渐下降而乌斯河铅锌野茼蒿的根长及株高总体呈逐渐上升的趋势；两地野茼蒿地上部分生物量均大于根部；叶片中叶绿素均在最高浓度处理下含量最小；富泉铅锌矿野茼蒿POD及SOD活性随处理浓度的增加而呈先增大后减小的趋势,乌斯河铅锌矿则逐渐增加；在高浓度处理下两地野茼蒿叶片CAT活性与低浓度处理相比均显著下降(P<0.05)。Pb在野茼蒿叶片细胞壁、细胞器和胞液中的分布因地点而异,富泉铅锌矿以胞液为主(64.43%),而乌斯河铅锌矿以细胞壁为主(51.33%)；Pb在两地铅锌矿野茼蒿地上部含量分别达到128.71 mg kg-1及67.42 mg kg-1,根部分别达到747.84 mg kg-1.和1136.41mgkg-’,植物体内最大累积量分别为0.23mg及1.6mg；两地迁移系数及富集系数均未达到1。
(3)在Zn胁迫下,两地野茼蒿表现出相似的耐性特征；随胁迫浓度增加,富集能力均逐渐增强。各个处理下,两地野茼蒿根长及乌斯河铅锌矿株高均低于对照；地上部分生物量均大于根部且在最高浓度处理时均最小分别为0.06 g(FQ)及0.19g(WS)；叶片中叶绿素含量均在最高浓度处理时最小；两地叶片POD活性最大为731.16Ug-1 FW(处理T7)及955.79Ug-1 FW(处理T3)；最高浓度处理下,富泉铅锌矿叶片SOD活性最小为120.34 Ug-1 FW,乌斯河铅锌矿最大为160.97 Ug-1 FW;富泉铅锌矿野茼蒿叶片随处理浓度的增加其CAT活性呈先升高后降低的趋势,乌斯河铅锌矿野茼蒿叶片CAT活性则随处理浓度的增加而增强。最高浓度处理下,Zn在两地野茼蒿叶片胞液组分中含量均最大；Zn在两地铅锌矿野茼蒿地上部含量分别达到3155.63 mg kg-1.3331.40 mg kg-1根部的分别达到4877.10mg kg-1,7018.18mg kg-1,植物体内地上部分的最大累积量分别为3.28mg及2.74 mg；两地野茼蒿对Zn的富集系数均大与迁移系数。
综上所述,野茼蒿对镉具有超富集能力；并对铅和锌具有一定的耐性和富集能力,从其累积量、根部含量、生物量及良好的生长状况来看,对污染土壤有一定的修复作用。
Heavy metal pollution of metal mining and the surrounding soil has been a serious problem, because of its toxicity to environment and humans. Continue to search for and study rapidly growing and accumulator or hyperaccumulator plants and it was significance to phytoremediation and restoration of the ecological environment. This study selected Crassocephalum crepidioides (Benth.) S. Moore of two lead-zinc mine areas in Han Yuan as the research object, The main results were as follows:
(1) Under the Cd stress,Crassocephalum crepidioides (Benth.) S. Moore showed some tolerance characteristics; with the increase of stress concentration, Cd accumulation capacity was gradually increased. Under the highest concentrations,height, root length, biomass and chlorophyll were significantly decreased compared to control(P<0.01),With the increase of concentration,peroxidase(POD) in leaves increased at first then decreased,dismutase(SOD) and catalase(CAT) were gradually decreased.In Cd treatments,various concentrations of Cd contents showed cell wall>organelles>cytosol;Cd contents in plants were increased with increasing concentration;The maximum content of shoot reached 1289.48mg kg-1, The maximum accumulation in plants was 1.24 mg plant-1; TF and BCF were both greater than 1.
(2) Under the Pb stress, The two Crassocephalum crepidioides (Benth.) S. Moore showed different tolerance characteristics; with the increase of stress concentration, Pb accumulation capacity was gradually increased. Root length and plant height of FQ were gradually decreased with the increase of concentration, while, WS showed a gradual upward trend; Biomass of shoots were higher than that in roots of FQ and WS; Chlorophyll content were the smallest under the highest Pb concentration;The activities of POD and SOD of FQ increased at first then decreased, while, WS were gradually increased; CAT in higher concentration were both significantly decreased compared to lower concentration (P<0.05). Pb content was the highest in cytosol (64.43%) of FQ, but the cell wall (51.33%) of WS. The maximum content reached 128.71 mg kg-1,67.42 mg kg-1 in shoots and 747.84 mg kg-1,1136.41mg kg-1 in roots respectively of FQ and WS.The maximum accumulation in plants were 0.23mg(FQ) and 1.6mg(WS);The TF and BCF were both lower than 1.
(3) Under the Zn stress. The two Crassocephalum crepidioides (Benth.) S. Moore showed the similar tolerance characteristics; with the increase of stress concentration, accumulation capacity was gradually increased. Various treatments, root length (FQ) and WS) and plant height (WS) were higher than control. Biomass of shoots were both higher than that in roots, when in the maximum concentrations they were 0.06 g (FQ) and 0.19g(WS); Chlorophyll content was the smallest under the highest concentration; The maximum activities of POD were 731.16 Ug-1 FW(T7),955.79 Ug-1 FW(T3) respectively; Under the highest concentration, SOD activity of FQ was the lowest (120.34 Ug-1 FW), while, WS was the highest(160.97 U g-1 FW). With the increase of concentration, the activity of CAT (FQ) in leaves increased at first then decreased, while, WS were gradually increased.Under the highest concentrations, Zn contents were both the highest in the cytosol. The maximum content reached 3155.63 mg kg-1,3331.40 mg kg-1 in shoots and 4877.10 mg kg-1,7018.18mg kg-1 in roots respectively of FQ and WS.The maximum accumulation in shoots were 3.28mg(FQ) and 2.74(WS);The TF were both lower than The BCF.
In summary,Crassocephalum crepidioides (Benth.) S. Moore had a strong accumulation ability of Cd, while, some tolerance and accumulation ability of Pb and Zn. It had a certain function to contaminated soil repair according the accumulation, content of roots, biomass and the good growth conditions.
引文
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