利用熱處理逆境以增強螯合劑對鎘的植生萃取效率

植生復育(phytoremediation)是近年來廣受注目的生物技術整治土壤重金屬的方法之一，而其中利用植物大量吸收土壤重金屬以達到降低場址污染物濃度的植生萃取(phytoextraction)技術，其優點是可使土壤保有原來性質，是一環境友善的整治手段。通常在添加螯合劑增加土壤重金屬溶解度後，可提高植物的吸收量，另外植物在高溫逆境下根部也會提高對重金屬的吸收能力。因此，本研究以澆灌熱水至土壤的方法來增強2種螯合劑(EDDS及NTA)之植生萃取效果，在取強酸性紅壤添加不同濃度鎘(10、20、30 mg/kg)後，種植蕹菜(Ipomoea aquatic Forsk)及大豆(Glycine max (L.) Merr.)以評估植生萃取效果。實驗結果顯示，熱處理使根域土壤溫度達50 ℃，可提高蕹菜及大豆根部對鎘的吸收。在植體累積重金屬部分，蕹菜及大豆累積重金屬的機制不同，且蕹菜較大豆適合作為植生萃取鎘的作物。添加2.5及5 mmol/kg NTA為蕹菜植生萃取鎘最佳的螯合劑施用劑量，並且於收穫28天後，僅於10 mg/kg鎘污染土中恐有將重金屬淋洗至地下水的疑慮。依本實驗結果顯示，於10、20及30 mg/kg鎘污染土壤中，復育至農地管制標準(5 mg/kg)分別需要11、25及57年的時間。

關鍵字

乙二胺二琥珀酸；三乙酸基氨；鎘；植生萃取；蕹菜；大豆；植物逆境

並列摘要

Phytoremediation is much paid attention and is one of biotechniques of soil remediation for heavy metals. Additionally, phytoextraction is environmental friendly, which advantage is to clearly reduce heavy metal content in the contaminated soil. After phytoextraction, the remediated soil can be applied for agricultural use. The uptake of heavy metal by plant can be not only enhanced by spiking chelating agents, but also promoted by root stress of heat. Therefore, the hot solutions of EDDS and NTA respectively were spiked into Cd (10, 20, and 30 mg/kg) contaminated soil with strong acidity and clay texture. Water spinach (Ipomoea aquatic Forsk) and soybean (Glycine max (L.) Merr.) were further planted on the soils to evaluate the efficiency of Cd phytoextraction. Experimental results indicated the root uptake of Cd increased in the soil which root zone was heated to 50℃. Regarding Cd accumulation in the shoot, water spinach is more efficient than soybean in phytoextraction. These two crops are different in the accumulating mechanism of Cd. The optimal dosage of NTA is 2.5 and 5 mmol/kg for NTA. However, the soluble Cd is considered to be leached into groundwater in the soil with Cd 10 mg/kg after 28 days of the crop harvest. Throught the phytoextraction, the required times in reducing the Cd contents from 10, 20, and 30 mg/kd for meeting the arable soil standard (5 mg/kg) are 11, 25 and 57 years, respectively.

並列關鍵字

[S,S]-ethylenediaminedisuccinic acid ； nitrilotriacetic acid ； Cadmium ； Phytoextraction ； Ipomoea aquatica Forsk ； Glycine max (L.) Merr. ； Plant stress

參考文獻

賴鴻浴，2004，EDTA對促進重金屬鎘鋅及鉛污染土壤植生復育之研究，國立台灣大學環境工程研究所博士論文，台北市，第8-12頁。

Araujo, J. do C. T. de, and Nascimento, C. W. A. do, 2009, “Phytoextraction of Lead from Soil from a Battery Recycling Site: The Use of Citric Acid and NTA,” Water, Air, Soil Pollut., DOI 10.1007/s11270-009-0285-4.

Baker, A. J. M., 1981, “Accumulators and excluders-strategies in theresponse of plants to heavy metals,” J. Plant Nutr., 3: 643-654.

Balestrasse, K. B., Gallego, S. M., and Tomaro, M. L., 2004, “Cadmium-induced senescence in nodules of soybean (Glycine max L.) plants,” Plant Soil, 262: 373-381.

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 phytoremediation of high soil selenium,” J. Environ. Qual., 26:639-646.

國際替代計量

利用熱處理逆境以增強螯合劑對鎘的植生萃取效率

全文下載

主題瀏覽