以選擇性離子交換樹脂抽出法評估添加堆肥處理降低污染土壤有效性六價鉻含量及植物毒性之效果

Using the Selective Ion Exchange Resin Extraction Method to Evaluate the Effect of Compost Amendments on the Availability and Phytotoxicity of Chromium (VI) in Soils

施幼娜(Yu-Na Shih)

指導教授 ： 李達源

國立臺灣大學/生物資源暨農學院/農業化學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.01259

摘要

土壤中鉻以二種型態存在：三價鉻﹝Cr3+﹞與六價鉻﹝Cr2O72-、CrO42-﹞。六價鉻對生物之毒性較三價鉻大，又移動性亦較三價鉻大。本研究之目的即探討添加二種堆肥處理﹝豬糞堆肥和牛糞堆肥﹞降低六價鉻污染土壤中有效性六價鉻含量的效果。
本試驗採用三種台灣代表性﹝平鎮系，太康系、將軍系﹞的土壤與一田間鉻污染土壤﹝彰化系﹞。在三種代表性的土壤中添加不同濃度之K2Cr2O7溶液，使土壤含有0、175、250、400、500 mg Cr / kg soil，乾濕交替三次。再分別添加堆肥﹝豬糞堆肥(PM)與牛糞堆肥(CM)﹞於四種供試土壤中，使每公斤土壤增加0、50、150 g的有機質。於田間容水量，15℃下孵育20、40、60天。本試驗利用選擇性離子交換樹脂﹝DOWEX M4195﹞，經銅飽和作為無限匯池，抽出土壤中有效性的六價鉻。
結果顯示，添加二種堆肥處理後樹脂抽出土壤中有效性六價鉻的濃度均顯著降低。土壤抽出有效性六價鉻含量會隨堆肥孵育時間的增加而減少。在添加等量的堆肥處理時，牛糞堆肥比豬糞堆肥在降低土壤中有效性六價鉻含量的效果較大。添加堆肥對降低三個供試土壤中有效性六價鉻含量的效果不同，太康系土壤由於有效性六價鉻濃度較高，在土壤經孵育60天後，土壤有效性六價鉻含量之降低量較平鎮系與將軍系土壤大。本研究亦利用孵育60天之土壤做為Neubauer生物試驗，藉小麥幼苗生長狀況來探討添加不同量的堆肥處理於不同六價鉻添加濃度之土壤，可抽出有效性六價鉻含量對植物生長的影響。結果顯示小麥的株高與乾重會隨樹脂抽出土壤有效性六價鉻含量的增加而降低，顯示小麥的生長會受到土壤有效性六價鉻的毒害，進而使其生長受到抑制。另外，比較添加與未添加堆肥處理的鉻污染土壤，添加堆肥可有效的使樹脂抽出有效性六價鉻含量明顯減少，而使小麥受到的毒害明顯降低。在本試驗中田間鉻污染土壤﹝彰化系﹞中，其鉻全量雖然高達3070 mg kg-1，但樹脂抽出有效性六價鉻含量非常低，且其Neubauer生物試驗小麥並無毒害現象。顯示和鉻全量測定方法相比，選擇性離子交換樹脂抽出法測定之土壤有效性六價鉻含量較適合用來評估土壤鉻對植物的毒害。

關鍵字

樹脂 ； 小麥 ； 堆肥 ； 鉻

並列摘要

Chromium in soil is presented in two forms: Cr(Ⅲ) cation and Cr(VI) oxyanions. Chromium(VI) is more toxic and mobile than Cr(Ⅲ). In this study, two kinds of composts (hog-dung compost and cattle-dung compost) were applied to investigate their effects on the decrease of availability of Cr(VI) in Cr(VI)-contaminated soils.
Three representative soils of Taiwan [Pingchung (Pc), Chingchung (Cf), and Taikang (Tk)] and one Cr-contaminated soil [Changhua (Cc)] were used in this study. Three representative soils were added with K2Cr2O7 solutions to reach the level of 0, 175, 250, 400, and 500
mg Cr / kg respectively and gone through 3 drying and wetting cycles to prepare Cr(VI)-spiked soils. Composts were added with the three rates of 0, 50, and 150 g organic matter per kg soil into the Cr(VI)-spiked soils and one Cr-contaminated soil and incubated at 15℃ and field capacity for 20,40, and 60 days respectively. After incubation, the Cu-saturated selective ion exchange resin (DOWEX M4195) was used as an infinite sink to extract soil available Cr(VI).
Results from this study indicate that the amounts of resin-extractable Cr(VI) decreased in the Cr(VI)-spiked soils after amendment with two kinds of composts and the extent of reduction increased with the increase of the length of incubation time after compost addition. With the same amount of compost application, cattle-dung compost had larger extent in reducing the amount of soil extractable Cr(VI) than hog-dung compost. For the Cr-spiked soils with the same level of Cr(VI) addition, because Tk-soil had the largest contents of resin-extractable Cr(VI) among the three Cr(VI) spiked soils, the amonts of decrease of resin-extractable Cr(VI) was larger in Tk-soil than those in Pc-soil and Cf-soil with the addition of composts and incubation for 60 days. In this study, Neubauer test was also used to investigate the effect of amending with composts on the growth of wheat seedlings in the Cr-spiked soils. The results show that the height and dry weight of wheat seedlings in the Cr-spiked soils decreased with the increase of amount of soil extractable Cr(VI) by the resins. It indicates that the growth of wheat seedlings was inhibited by the soil extractable Cr(VI). The extent of growth inhibition of wheat seedlings was significantly reduced when amending with composts into Cr(VI) spiked soils, resulting from reducing the soil available Cr(VI) by adding composts. The above results indicate that addition of composts can decrease the amount of soil available Cr(VI) and thus reduce the phytotoxicity of Cr of Cr(VI)-contaminated soils. In addition, for the Cr-contaminated soil (Cc-soil) with total Cr concentration of 3070 mg kg-1, the amount of resin-extractable Cr(VI) was very low and the growth of wheat seedlings on this soil was not inhibited, indicating that the amount of extractable Cr(VI) determined by the selective ion exchange resin method is more suitable than total amounts of Cr for evaluating the phytotoxicity of Cr in Cr-contaminated soils.

並列關鍵字

wheat ； resin ； chromium ； compost

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