【作者】 于彩莲；

【导师】 刘波；

【作者基本信息】 哈尔滨理工大学 ， 材料学， 2011， 博士

【摘要】 镉(Cd)污染土壤占重金属污染土壤总面积的40%左右,Cd以其毒性高,且容易被食物链所累积和放大,已经严重地影响了生态系统的安全。龙葵是修复土壤Cd污染的理想植物,但是在高Cd污染的土壤上其修复能力有限。生长调节剂能够增强植物对逆境的抵抗能力,缓解重金属胁迫所造成的不利影响,增加对重金属的累积量。然而植物生长调节剂能否提高龙葵对Cd污染土壤的修复效率还未见报道。为此,本文通过连续3年的盆栽试验,系统研究了龙葵在修复Cu、Zn、Pb、Cd等单一因素和复合污染中的作用,比较了复硝酚钠、2,4-D及DA-6等生长调节剂在修复Cd污染土壤中的作用,并在不同Cd污染的土壤上进行了DA-6的最佳用量试验,同时还探讨了DA-6和腐植酸联合施用后对Cd污染修复的强化作用,以期揭示DA-6对龙葵修复Cd污染土壤的影响机制。取得的主要研究结果如下：1.龙葵修复多种重金属污染土壤Cu、Zn、Pb和Cd四种重金属的复合污染促进了龙葵的生长,根、茎、叶干重最高；在复合污染中,龙葵能同时富集一定量的Cu、Zn、Pb和Cd,植株各器官中的各金属浓度和累积量均为最高,但是对Cu、Zn和Pb富集系数均小于0.6,而地上部对Cd的富集系数接近2,地下部对Cd的富集系数高于3。以上结果表明：龙葵在多种重金属存在下,对土壤中Cd仍具有较强的富集能力。2.常用生长调节剂对龙葵修复高Cd污染土壤100mg/kg的高Cd污染土壤抑制了龙葵的生长,使龙葵株高和干重显著降低。生长调节剂2,4-D和DA-6能显著促进龙葵的生长,增加其生物量。但明显低于无Cd处理。施用的三种调节剂使成熟期龙葵地上Cd累积量增加了20.93%-26.74%(P<0.05),地下Cd累积量增加了0.5-1.33倍(P<0.05),总累积量增加了24.49%-39.8%(P<0.05),其中DA-6>2,4-D>复硝酚钠。由于生长调节剂的作用,使抗氧化系统酶的活性显著提高,增强了清除超氧自由基阴离子的能力,减轻了膜脂过氧化损伤,使MDA含量以及叶片的相对电导率显著降低,提高了龙葵叶片SPAD值,其中DA-6降低作用最显著。3.DA-6强化龙葵修复多浓度Cd污染土壤DA-6能够不同程度地增加龙葵地上和总Cd的累积量,10 mg/L的DA-6对土壤Cd浓度为10、25和50 mg/kg土壤的修复效果显著,地上Cd累积量最高增加了81.87%；20 mg/L的DA-6对土壤Cd浓度为100 mg/kg土壤的修复效果显著,使龙葵地上和总Cd累积量增加了36.38%和34.54%,强化效果显著。相同剂量的DA-6对不同Cd浓度污染土壤的作用效果不同,只有适宜浓度的DA-6处理才能最大程度地降低龙葵叶片中MDA含量。在土壤Cd浓度为0和25 mg/kg条件下,40 mg/L的DA-6处理效果最显著；而在土壤Cd浓度为10、50和100 mg/kg条件下,10和20 mg/L的DA-6处理效果比较显著。DA-6处理还能增强叶片中POD活性,提高SPAD值,从而提高了对不良环境的抵抗能力,促进了龙葵的生长,因此提高了对土壤Cd污染的修复能力。4.腐殖酸和DA-6联合强化龙葵修复Cd污染土壤在DA-6和腐殖酸作用下,随着Cd浓度提高,龙葵干物质积累先增加,到25 mg/kg达最大,然后下降。随着Cd浓度提高,龙葵植株和根中Cd浓度提高,根系对Cd的富集系数明显增大,Cd总积累量显著提高。腐植酸能提高龙葵修复Cd污染土壤的能力,与DA-6配合施用能使这种能力得到加强。更多还原

【Abstract】 About 40 percent soil contaminated by heavy metals is associated with Cadmium (Cd). Cd, a high toxicity metal, is easily accumulated in soil and enlarged in the food chain and Cd contamination has negatively influenced the safety of the ecosystem. Solanum nigrum L.is an ideal plant in the restoration of soil contaminated by Cd. However, remediation capacity of Solanum nigrum L. is limited in high Cd soil. Plant growth regulators play important role in increasing stress tolerance, enhancing heavy metal accumulation, and alleviating the adverse impact of heavy metal. However, the effect of plant growth regulator on Cd remediation efficiency of S. nigrum L. remains to be unknown.3 years’pot experiments were carried out to investigate the remediation effect of S. nigrum L. on soil with single and compound contamination of Cu, Zn, Pb and Cd. It compared among compound sodium nitrophenolate, diethyl Aminoethyl hexanoate and 2,4-D in the effect of remediation on Cd contaminated soil. Optimum dosage of DA-6 screening test in different Cd contamination soil was also estimated in this study. Moreover, The combined effects of DA-6 and humic acid on Cd contamination soil were investigated to reveal the effect of DA-6 on the remediation of S. nigrum L.. The main results were indicated as follows:1. A study of S. nigrum L. in remediation of heavy metals contaminated soil.The growth of S. nigrum L. was promoted significantly by Cu, Zn, Pb and Cd compound contamination. Dry weight (DW) of roots, stems and leaves in treatment with compound contamination were highest in all treatments. Cu, Zn, Pb and Cd concentration and accumulation under the condition of compound contamination were higher than that under the single contamination. S. nigrum L. played an important role in accumulating the Cu, Zn, Pb and Cd. The accumulation coefficient (AC) was less than 0.6, whereas the shoot and root AC of Cd was nearly to 2 and above 3 respectively. The results showed that S. nigrum L. had strong enrichment capability of Cd in a variety of heavy metals.2. The effects of growth regulator on the abitity of S. nigrum L. in remediation soil seriously contaminated with Cd. The growth of S. nigrum L. was significantly restrained by 100 mg/kg Cd, showed that height and DW of S. nigrum L. were decreased under Cd treatment. However,2,4-D and DA-6 could promote the growth of S. nigrum L. and increased its resistance under Cd stress, but the accumulation of dry matter was significantly lower than the accumulation without Cd treatment. During S. nigrum L. maturity, compound sodium nitrophenolate,2,4-D and DA-6 increased the Cd accumulation on the ground by 20.93%-26.74%(p<0.05); The underground Cd accumulation increased by 0.5-1.33 times(p<0.05); and the total cumulative content increased by 24.49%-39.8%(p<0.05). The increasing order was:DA-6> 2,4-D>compound sodium nitrophenolate. Three plant growth regulators increased the activities of SOD and CAT, so the ability of scavenging superoxide free radical anion got enhanced, effects on Cd toxicity in the leaves of S. nigrum L. got alleviated and its Cd-resistant got enhanced. The application of three growth regulators significantly reduced the content of MDA and relative conductivity, increased the SPAD value. DA-6 was the most prominent one.3. A study on ability of DA-6 in enhancing remediation different Cd concentrations soil by S. nigrum L.When DA-6 was 10 mg/L, the ability of S. nigrum L. in accumulating Cd was the strongest with concentration of Cd in soil under 50 mg/kg, and the Cd accumulation in S. nigrum L. reached 81.87%.20 mg/L DA-6 was best for S. nigrum L. in remeding the soil contaminated with 100 mg/kg Cd. The aerial parts and total accumulation of Cd increased 36.38% and 34.54% respectively, and the effect of enhancing remediation was significant.There were great differences with the same dosage DA-6 on the different concentration of Cd in soil. It worked only by appropriate concentration of DA-6. On the condition of Cd concentrations in soil were 0 and 25 mg/kg, concentration of DA-6 which was 40mg/L got the least MDA content in S. nigrum L.. When Cd concentrations in soil were 10,50 and 100 mg/kg, DA-6 which were 10 and 20 mg/kg made the content of MDA lower. Treatments with appropriate concentration of DA-6 increased POD activity and SPAD value in S. nigrum L. leaves. Therefore, it enhanced the ability to resist the adverse environmental, also promoted the growth of S. nigrum L., thus improving the ability to remedy soil with Cd contaminated.4. A study on DA-6 combinated with humid acid enhancing remediation of soil contaminated by Cd.With the increase of Cd concentrations, dry matter of S. nigrum L. increased at first, and reached a peak when Cd concentrations was 25 mg/kg, then declined. Cd accumulation in S. nigrum L. shoot and root markedly improved with the increase of Cd concentration and total Cd accumulation enhanced significantly. Application of humic acid alone and combinated with DA-6 could improve the total Cd accumulation significantly. Results showed that DA-6 significantly enhanced remediation coefficiency of S. nigrum L. on Cd contaminatede soil, especially humic acid combinated with DA-6.更多还原