灌溉水質對農地土壤重金屬污染與水稻重金屬含量及根圈土壤低分子量有機酸之影響

Effect of Irrigation Water Quality on Heavy Metal Pollution of Paddy Field Soil, Heavy Metal Contents of Paddy Rice, and Low Molecular Weight Organic Acids in Rhizosphere Soil

閻涵文(Han-Wen Yen)

指導教授 ： 張簡水紋 ； 王敏昭

朝陽科技大學/理工學院/環境工程與管理系/碩士(2010年)

摘要

都市及工業廢水常會藉由灌溉渠道進入農田，造成農田汙染，重金屬的議題被關心主因為重金屬無法被自然中生物所分解以及對人體健康的潛在影響，在台灣許多工廠排水系統為灌排不分離，導致廢水經由灌溉渠道排入農田造成如Cd、Zn、Cu、Cr、Ni及Pb等重金屬造成土壤污染，當廢水中含有重金屬進入土體，造成地下水污染或藉由土壤溶液被植物所吸收。本研究模以灌溉水pH值的改變對土壤性質與水稻吸收重金屬(Cd、Zn、Cu、Cr、Ni、Pb)之影響，研究中使用來自受工業區廢水污染之土壤，以盆栽試驗探討pH值受重金屬污染土壤之影響，結果顯示酸性灌溉水對於稻米成長影響甚小，不論地上部或地下部之植體，所測得之重金屬鎘、鉻、銅及鋅呈現差異顯著，且當pH 值調降愈低時，植體中重金屬濃度愈高，故調降灌溉水pH 值會影響植體中重金屬含量。從土壤中重金屬濃度發現鉻在盆栽試驗中皆呈顯著差異，重金屬中最容易受pH 值之影響。98 年二期作土壤鎘在pH 值調降3 隔次處理時濃度最低，但在糙米及莖葉鎘在pH 值調降3 隔次處理時濃度最高，顯示出此處理造成土壤中鎘溶出最多進而被植體吸收造成此現象。98 年二期作中探討植體與土壤重金屬濃度與低分子量有機酸之相關性，結果顯示糙米鉻濃度提高時，草酸及乙醛酸濃度隨之增加，鋅濃度增加時，草酸濃度也增加；而莖葉鎘濃度提高時，反丁烯二酸及蘋果酸濃度也隨之增加另外根部鉛及鉻濃度增加時，乙醛酸濃度也隨之增加且當土壤中銅濃度較高時，左旋乳酸也隨之增加。

關鍵字

酸性廢水 ； 稻米 ； pH ； 低分子量有機酸 ； 灌溉水 ； 重金屬

並列摘要

The use of industrial or municipal wastewater to the farm land by irrigation channels causes the pollution of cultivated agricultural lands. Among various pollutants heavy metals are the most serious concerned because of their nonbiodegradable nature and potential impact on human heath. Many factories in Taiwan discharged their effluents/wastewater into drainage and supplied to the farm lands through irrigation channels, since there is no separate system for drainage and irrigation channels. It is known that soils irrigated by wastewater accumulate heavy metals such as Cd, Zn, Cu, Cr, Ni and Pb in surface soil. When the capacity of the soil to retain heavy metals is reduced due to repeated use of wastewater, soil can release heavy metals into ground water or soil solution available for plant uptake. This study describes the effect of pH changes of irrigation water on soil heavy metal pollution from industrial and municipal wastewater and subsequently the uptake of Cd, Zn, Cu, Cr, Ni and Pb heavy metals by rice plant have been investigated. In this study, soil was collected from polluted farm land which is irrigated with wastewater from industrial and urban areas. Pot experiments were conducted by growing rice plants to study the effect of pH on soil heavy metal pollution at original irrigation water pH (around at 7.0) and below original irrigation water pH (1.5 and 3.0) and found that Cd, Cr, Cu and Zn exhibit significant difference with the change of pH values. When the pH value of irrigation water is lower than original irrigation water pH, the observed concentration of heavy metals uptake by all parts of rice plant was higher. After crop production was over, the stems and leaves of the rice plants and soil were examined to determine the concentrations of heavy metals and found that cadmium was highest concentration among studied heavy metals at pH value lower than original irrigation water pH compared to other pH values. It indicates that rice plant highly uptake of cadmium from contaminated soil which is irrigated by wastewater. The results showed that the soil was affected by acidic irrigation water and uptake of the heavy metals by rice plant significantly different with the pH values. During the growth of rice plant, effect of low molecular weight organic acids on heavy metal pollution in different parts of rice plant was determined. The results showed that Cr concentration was higher in rice, the oxalic acid and glyoxylic acid concentration in soil was also higher observed. In stems of the rice plant the concentration of Cd positively correlated with the concentrations of fumaric and malic acid. Glyoxylic acid concentration in soil was correlated with the concentrations of Pb and Cr in roots of rice plant. In soil the concentration of Cu correlated with L-(+) Lactic acid concentration.

並列關鍵字

Wastewater ； Irrigation water ； Heavy metals ； Rice plant ； Acidic water ； pH

參考文獻

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