白楊與太陽麻對污染土壤中重金屬之忍受性與累積性
Other Title
Heavy-Metal Tolerance and Accumulation off Poplar and Sun Hemp Grown on a Contaminated Site
Journal
土壤及地下水污染整治
Journal Volume
1
Journal Issue
2
Start Page
103
End Page
114
ISSN
2313-2736
Date Issued
2014
Author(s)
Abstract
本研究場址位於屏東縣九如鄉，範圍為1,800m^2，主要污染重金屬為鋅(Zn)、鉻(Cr)、銅(Cu)、鎳(Ni)。研究之主要目的在於以植生復育法改善污染，亦即在污染場址中栽植白楊與太陽麻，藉由植物之吸收、累積與植體移除而逐漸降低重金屬濃度。試驗方法乃依土壤調查結果於場址內設置6個試驗區，其中五個位於污染區域之處理區(PR1~PR5)，另外於無污染區域設置一個對照區(CK)，且分別栽植復育植物。研究結果發現，主要污染重金屬在各試驗區所有土層中之濃度呈現不規則變化，且大多數皆高於土壤污染管制標準。其次，生育調查與生理試驗之結果皆顯示，兩種復育植物在試驗區中生長良好，且處理區與對照區並無顯著差異，屬於耐污染物種，有益於後續之污染物改善試驗。此外，兩種植體重金屬之吸收累積量以Zn最大，其餘略呈Cu＞Ni＞Cr之現象。最後以移除植體之生質量與重金屬濃度計算土壤重金屬之移除量，結果得知，太陽麻與白楊對重金屬之總移除量，亦即對重金屬之植生復育效益分別為Zn(84g)＞Cu(1.93g)＞Ni(1.45g)＞Cr(0.38g)。此移除量若與五個處理區推估之土壤重金屬總量相較，其移除比例尚低，故復育期可能甚長，惟當白楊樹長大後，其生質量必可快速增加，復育時程亦將大幅縮短。
The contaminated site proposed in this study is located in Pingtung County, with an area of 1,800 m^2. According to the results from previous investigations conducted by competent authorities, the maximum concentrations of zinc (Zn), chromium (Cr), copper (Cu), and nickel (Ni) were found to be 51,800, 711, 586, and 555 mg/kg, respectively. Since the heavy metal contents exceed Taiwan’s Soil Pollution Control Standards, the site was then announced as a soil pollution control site that requires remediation. The objective of this research was to conduct phytoremediation in the contaminated site. Five remediation plots (PR1~PR5) were designated in the highly contaminated area, and one control plot (CK) was used for comparison purposes. Poplars (＂Populus bonatii Levl.＂) and Sun Hemp (＂Crotalaria juncea L.＂) were utilized in the phytoremediation practice and were planted in all plots. The soil heavy metal contents of each plot were analyzed to evaluate their impact on plant growth. Growth investigations, including growth and weight measurements, and physiological experiments, including photosynthetic rates and maximal photochemical yield of chlorophyll fluorescence (F_v/F_m), were used to evaluate the level of plant stress caused by pollutants. Biomass and heavy metal concentration in plant tissues were also determined to calculate the amount of each element removed from soils. The results from soil analysis indicated that the heavy metals were distributed from the surface to 100 cm. Height and weight measurements of the two plants indicated that there were no significant differences between the plants in the remediation plots and those in the control plot. The physiological investigation data of the Poplars also suggested a high tolerance level to the contaminated soils. In other words, these results demonstrate that the plants were healthy and suitable for this remediation study. The results from tissue analysis indicated that the four heavy metals were absorbed and accumulated in the order of Zn ＞ Cu ＞ Ni ＞ Cr. To explore in further detail, the biomass and heavy-metal contents of the studied plants were used to calculate the removal amounts. The four contaminants removed by Sun Hemp were in the descending order of Zn (50.8 g) ＞ Cu (1.735 g) ＞ Ni (1.186 g) ＞ Cr (0.331 g), and those by Poplars were Zn (33.2 g) ＞ Ni (0.260 g) ＞ Cu (0.188 g) ＞ Cr (0.048 g). By combining both results, the total removal amounts in this study would then be 84 g for Zn and 1.93 g, 1.45 g, 0.38 g for Cu, Ni, and Cr respectively. By comparing the amounts of heavy metals removed by plants and the estimated amounts in soils, we found that the phytoremediation effect is low, and hence it takes long-term practice to reach the recovery goal. However, as the growth and maturity of Poplars leads to a dramatic increase in biomass, the time to reach the goal may be shortened by using this plant.
Subjects
重金屬
植生復育
白楊
太陽麻
heavy metals
phytoremediation
poplar
sun hemp
Type
journal article