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  • 學位論文

螯合劑與有機酸對促進蕹菜吸收底泥中鎘、鉛效率比較

Efficiency of chelators and organic acids on enhancing the absorption of cadmium and lead by Lpomoea aquatic in a sediment

指導教授 : 邱春惠

摘要


植生復育(phytoremediation)可利用植體的生長累積重金屬以移除底泥中重金屬含量,雖然相較於其它處理方式需較長的處理時間,但對環境衝擊較小,同時也是屬於成本較低廉的重金屬整治技術。添加螯合劑可促進重金屬由底泥釋出,以增強植物吸收效果,但有污染地下水的疑慮。 本研究配製鎘、鉛濃度分別為(2.5、250);(5、500);(7.5、750);(10、1000);(15、1500) mg/kg底泥,種植蕹菜(Ipomoea aquatic)並於每週施用EDTA (Ethylene diamine tetraacetic acid)、EDDS ([S,S]-Ethylene diamine disuccinic acid)、及低分子有機酸(琥珀酸、草酸、醋酸及檸檬酸),分析各週底泥抽出水溶液、植栽最後植物根部及地上部的鎘及鉛濃度,以評估螯合劑與有機酸對底泥中鎘及鉛的溶出及植物吸收的效果。 實驗結果顯示,在15 mg Cd/kg、1500 mg Pb/kg底泥中,水溶液鎘、鉛濃度皆以EDTA處理最高,分別為13.2~6.45、200~93.7 μg/L,但在其它處理水溶液鎘鉛濃度皆較低(0~1.16 μg/L);植物根部累積鎘濃度以EDDS(10.8~13.8 mg/kg)最好,EDTA(8.10~11.5 mg/kg)次之;地上部以EDTA(6.10~14.3 mg/kg)最高。而鉛的累積隨著配製底泥濃度增加,植體根部累積鉛濃度也隨之增加,無論是根或地上部皆以EDTA(248; 113 mg/kg)最好。 BCF(Bioconcentration factor)皆以未添加鎘鉛時最高,15 mg Cd/kg、1500 mg Pb/kg時鎘BCF最低,且隨鎘濃度提高BCF皆呈現下降現象;鉛的BCF於各配製底泥中,皆遠小於鎘BCF,且以EDTA處理組BCF最高(0.08至0.58)。EDTA處理的轉移係數(Transfer factor, TF)比EDDS高,較能將根部的鎘轉移至地上部;而鉛的TF同樣也小於鎘TF,於未添加鎘鉛底泥時以醋酸處理組效果最佳,而在1500 mg Pb/kg底泥時則以未添加螯合劑、EDDS及EDTA處理組效果較佳。 蕹菜種植於五種鎘配製底泥中之植體與水溶液鎘濃度比,以醋酸最高(6.11×104~6.49×104),EDTA最低(1.64×103~1.15×105),在鉛的部分,隨底泥鎘鉛濃度提高,EDTA處理會有濃度比下降的趨勢(1.67×104~1.27×103),而其它處理皆有上升趨勢。鎘總量分布於五種鎘鉛配製底泥,以EDDS處理下鎘分布至植體最高(85.4‰ ~ 2.48‰),而EDTA處理則於水溶液分布最高(2.58‰ ~ 0.40‰);鉛總量分布,EDTA處理植體(0.24‰ ~ 0.53‰)及水溶液(0.0235‰ ~ 0.0086‰)含量皆遠高於其它處理植體(0.08‰~0.20‰)及水溶液(0.00001‰ ~ 0.00054‰)含量,整體而言使用螯合劑與有機酸經植生萃取1個月可將高污染鎘鉛底泥中的鎘鉛移去0.1~10%的含量且對鎘的效益比鉛高。

關鍵字

植生復育 EDTA EDDS 螯合劑

並列摘要


Phytoremediation use the accumulation of heavy metal by the growth of plant to remove heavy metal from contaminated sediments. Although it requires a longer processing time compared to other treatments, it has less impact on the environment. Also, it is lower-cost heavy metal remediation technology. Chelating agents can be added to increase the release of heavy metals in the sediment, and enhance the effect of absorption of plants. However, it may cause groundwater contamination. In the study, Lpomoea aquatic is planted in five kinds of sediment contaminated by cadmium and lead, whose concentration is (2.5, 250) ; (5, 500) ; (7.5, 750) ; (10, 1000) ; (15, 1500) mg/kg repectively. Furthermore, we add 5 mmol/kg sediment of EDTA, EDDS, succinic acid, oxalic acid, acetic acid and citric acid weekly. We analyze the concentration of cadmium and lead from aqueous solution of sediments each week, from roots and shoots of the plant in the end of the experiment. Afterwards, we evaluate the dissolution of Cd and Pb from sediments with chelating agent and organic acid added and the performance of absorption of plants. The results show that the concentration of Cd and Pb in two kinds of aqueous solution is 13.2~6.45μg/L, 200~937 μg/L respectively when EDTA is added in the sediments of 15 mg Cd/kg and 1500 mg Cd/kg. However, the concentration of Cd and Pb is lower in other treatments (0~1.16 μg/L). The concentration of accumulated cadmium in roots is the highest (10.8~13.8 mg/kg) when we use EDDS. The concentration of that is second when we use EDTA (8.10~11.5 mg/kg). The concentration of accumulated cadmium in shoot is highest (6.10~14.3 mg/kg) when we use EDTA. The concentration of accumulated lead in root becomes higher as the concentration of sediments gets higher. The concentration of lead is the highest in both of roots and ground level when we use EDTA (248, 113 mg/kg). The BCF (Bioconcentration factor) of cadmium and lead is the highest without the addition of cadmium and lead. The BCF of cadmium is the lowest when the condition of sediments is 15 mg Cd/kg and 1500 mg Pb/kg. Morover, the BCF decreases when the concentration of cadmium gets higher. The BCF of lead is always lower the BCF of cadimum when any kinds of sediments are used. Besides, the BCF of lead is the highest under the EDTA treatment (0.08~0.58). The TF (Transfer factor) of EDTA treatment is higher than that of EDDS treatment, which means that cadimum is easier to be transferred from roots to shoot. Likewise, the TF of Lead is lower than that of cadimum. If the sediments are not added with Cd and Pb, the TF of lead is the highest when acetic acid is used. The TFs of lead are higher without chelating agent, in the treatments of EDDS and EDTA under the concentration of lead in the sediment is 1500 mg Pb/kg. In terms of cadimum, the ratio of the concentration of plants to the concentration of cadimum in aqueous solution is the highest in the treatment of acetic acid (6.11×104~6.49×104), and is the lowest in EDTA treatment (1.64×103~1.15×104) when Lpomoea aquatic is planted in all five sediments. In terms of Lead, the ratio of the concentration of plants to the concentration of lead in aqueous solution decreases (1.67×104~1.27×103) in EDTA treatment as the sediments contain more and more lead. However, it rises in any other treatments. In five different kinds of sediments, plants contain the most of cadimum (85.4‰ ~ 2.48 ‰) in the treatment of EDDS, and aqueous solution contains the most of it (2.58‰ ~ 0.40‰) in EDTA treatment. Plants (0.24‰~0.53‰) and aqueous solution (0.0235‰~0.0086‰) in EDTA treatment contain more lead than that plants (0.08‰~0.20‰) and aqueous solution (0.00001 ‰ ~ 0.00054 ‰) contain in any other treatments. Overall, if we use chelating agent and organic acid to extract the sediments of contaminated cadimum by phytoremediation for a month, we can remove 0.1%~10% of cadimum in those sediments. Besides, phytoremediation has better efficiency on cadimum than on lead.

並列關鍵字

cadmium lead phytoremediation EDTA EDDS chelating agents

參考文獻


行政院環境保護署,2009,全國環境水質監測資訊網,中華民國九十八年河川整體調查結果。
Adriaens, P., Li, M. Y., and Michalak, A. M., 2006, “Scaling methods of sediment bioremediation processes and application,” Engineering in Life Sciences, Vol. 3, pp. 21-227.
Banuelos, G. S., Ajwa, H. A., Mackey, B., Wu, L., Cook, C., Akohoue, S., and Zambruzuski, S., 1997, “Evaluation of different plant species used for phytoextractionof high soil selenium,” J. Environ. Qual., Vol. 26, pp. 639-646.
Barona, A., Aranguiz, I., and Elías, A., 2001, “Metal associations in soils before and after EDTA extractive decontamination: implications for effectiveness of further cleanup procedures,” Environ. Pollut., Vol. 113, pp. 79-85.
Blum, U., 1996, “Allelopathic interactions involving phenolic acids,” Journal of Nematol, Vol. 28, pp. 259-267.

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