添加熱活化蛇紋石粉末降低污染土壤中鎳的有效性與小麥吸收量

Abstract

隨著全球農業工業發展，土壤污染問題愈發受到人們重視。現地穩定法(in situ stabilization)是通過添加改良劑，將土壤中的重金屬吸附或沉澱，使其不易移動，以此降低重金屬的生物有效性，修復污染土壤的方法。本實驗選用熱活化的蛇紋石(serpentine)以及石灰石(limestone)作為改良劑加入鎳(nickel)污染土壤中，通過比較兩者對鎳污染土壤的穩定效果，來探討熱活化蛇紋石能否作為土壤改良劑修復鎳污染土壤。實驗採用的土壤為中酸性的鎳污染土壤，在實驗中分別添加不同比例的熱活化蛇紋石以及石灰石，孵育60天。孵育期間每隔30天採取土壤樣品測定pH值，每隔15天抽取土壤水檢測其中鉻與鎳的濃度。孵育結束後，利用EDTA單一萃取法(single extraction)以及BCR序列萃取法(sequential extraction)檢測土壤中鉻鎳型態之轉變。利用盆栽實驗種植小麥(Triticum aestivum)以評估改良劑修復效果，並通過植體分析比較不同處理組的小麥苗的鎳含量的差異。實驗結果顯示，熱活化的蛇紋石以及石灰石在加入土壤後都能提高土壤pH值，並且在150天孵育後仍能使土壤pH穩定為中性。根據EDTA萃取與土壤溶液的結果，兩種改良劑在加入土壤後都能顯著降低土壤中高移動性的鎳濃度。根據BCR序列萃取結果顯示，在加入改良劑後，高生物可及性的酸可溶態的鎳被轉換成了較穩定的鐵錳氧化物態與殘留態。結合上述結果，熱活化蛇紋石粉末在加入到土壤後可以穩定土壤中的鎳。

With the development of global agricultural and industrial sectors, soil pollution has received increasing attention. In situ stabilization is a method of repairing polluted soil by adding amendments to adsorb or precipitate heavy metals in the soil, making them less mobile and reducing their bioavailability. In this experiment, thermally activated serpentine and limestone were selected as amendments to be added to nickel-polluted soil to investigate whether thermally activated serpentine can be used as a soil amendment to repair nickel-polluted soil, by comparing the stabilization effect of the two amendments on nickel-polluted soil. The soil used in the experiment was nickel-polluted clay with medium acidity, and different ratios of thermally activated serpentine and limestone were added to the soil for incubation for 60 days. The pH value of the soil was measured every 30 days during the incubation period, and the chromium and nickel concentrations in the soil water were tested every 15 days. After incubation, the changes in chromium and nickel forms in the soil were detected by EDTA single extraction and BCR sequential extraction methods. The remediation effect of the amendments was evaluated by planting Triticum aestivum in a pot experiment, and the difference in nickel content in the Triticum aestivum among different treatment groups was compared through plant analysis. The results showed that both thermally activated serpentine and limestone could increase the soil pH value after being added to the soil, and could still stabilize the soil pH to neutral after 150 days incubation. According to the single extraction results, both amendments could significantly reduce the nickel concentration in the soil that can be extracted by EDTA after being added to the soil. The best stabilization effect was achieved by the 0.5% limestone group, with a decrease of 40.42% in the nickel concentration extracted by single extraction compared to the original soil.