鎵與銦在土壤中之有效性及其對小麥幼苗生長之影響

Abstract

新興汙染物鎵跟銦被廣泛運用在半導體製造業和光電產業，而隨著環境中鎵與銦濃度的提高，人類可能經由食用作物暴露到鎵與銦，並造成健康上的危害，因此，本研究以盆栽試驗種植小麥幼苗，評估鎵與銦在不同土壤中小麥生長之影響，以及以不同化學抽出法調查鎵跟銦在不同土壤中之有效性。以平鎮系、仁德系和太康系土壤作為供試土壤，分別添加 50、100、200 與 400 mg kg-1 的鎵或銦後再種植小麥，選用品種台中選二號之小麥作為試驗材料，種植滿 50 天後採收。另以 0.02 M CaCl2、0.1 M HCl 和1 M HCl 溶液進行土壤有效性鎵與銦萃取，並與植體鎵、銦濃度作相關性分析。在土壤單一萃取實驗中發現，以 1 M 和 0.1 M 鹽酸萃取的土壤鎵與銦濃度與小麥根部鎵與銦濃度和總吸收量均呈顯著正相關，然而，0.02 M 氯化鈣萃取的土壤鎵與銦濃度與小麥根部鎵與銦濃度和總吸收量相關性較差，因此，以 1 M 和0.1 M 鹽酸萃取的土壤鎵與銦濃度較適合做為土壤有效性鎵與銦的萃取方法。小麥的盆栽試驗結果顯示，小麥幼苗會吸收鎵和銦，且兩元素能在植體內被運輸，但大部分累積於根部。在中鹼性土壤 (太康系和仁德系) 中，鎵不會對小麥幼苗造成毒害，隨著鎵處理濃度提高，小麥幼苗根部與地上部生質量以及株高與控制組相比沒有顯著差異。而在太康系和仁德系的銦處理中，則是觀察到與鎵處理相似的結果，然而，在部分銦處理中，小麥幼苗根部生質量比控制組顯著下降，代表銦對小麥根部會造成部分毒害，但對整體生長勢影響不大。而在富含鋁的平鎮系土壤中，小麥均受到嚴重的鋁毒害，但是，酸性氯化鎵與氯化銦的添加會導致土壤 pH 值下降，並導致土壤活性鋁濃度增加，造成小麥幼苗更嚴重的鋁毒害現象。

Emerging contaminants gallium (Ga) and indium (In) are commonly used in semiconductor manufacturing industry and electro-optical industry. As the elevated concentrations of Ga and In in the environment, human beings might exposure to them via eating crops and caused health hazards. Therefore, pot experiments were conducted with wheat seedlings to assess the effects of Ga and In on the growth of wheat seedlings in various soil systems. Besides, the availability of Ga and In in different soils were investigated with different chemical extractants. Wheat seedlings (Triticum aestivum L.) were grown in three different soils spiked with 50, 100, 200 and 400 mg kg -1 of Ga or In, respectively. All wheat seedlings were harvested after 50 days. In addition, soil available gallium and indium were extracted with 0.02 M CaCl2, 0.1 M HCl and 1 M HCl, which later will compare with Ga and In concentrations and amount in plant tissues. In soil single extraction experiments, soil Ga and In concentrations extracted with 1 M and 0.1 M HCl have significant positive relationship with Ga and In concentrations and amount in wheat seedling roots. However, relationships between soil Ga and In concentrations extracted by 0.02 M CaCl2 and Ga and In concentrations and amount in wheat seedling roots are bad. Therefore, 1 M and 0.1 M HCl are better extractants to compare availability Ga or In in different soils. The pot experiments results revealed that wheat seedlings could absorb Ga and In, and transfer these two elements from root to shoot in the plant, but most of them were accumulated in root. In macro scale, gallium won’t cause toxic effects to wheat seedlings after 50 days exposure in neutral and alkaline soils (Taikang and Jente soils). No significant decrease in roots biomass, shoots biomass and shoot height was observed in wheat seedlings with increasing Ga concentrations. For the In treatment, we found the similar results as Ga treatment except for roots biomass in Taikang and Jente soils. Results indicated that the addition of In can cause little deleterious effects on roots of wheat seedlings. In aluminum rich Pinchen soils, the addition of acidic gallium chloride and indium chloride solution will decrease soil pH, and caused more serious aluminum toxicity to wheat seedlings.