XRF篩測及王水消化法分析土壤重金屬之比較

台灣現階段以王水消化法作為土壤重金屬標準的全量分析之方法，其分析數值與真實含量相比較為準確，但花費昂貴且需要時間較長。近年來X-射線螢光光譜儀(X-ray Fluorescence Spectrometer，以下簡稱XRF)應用於重金屬污染土壤現地快速篩測方法，與王水消化法相比分析時間短且經費相對也較低，現場即能快速篩選得知污染物約略濃度。本研究為瞭解XRF快速篩測土壤重金屬樣品數據之可靠性與準確性，擇用台灣甲、乙區域場址土壤，除現地篩測XRF之外，將待分析土壤重金屬樣品進行土壤前處理，通過10mesh及100mesh標準篩網後再以王水消化法使待測金屬成為溶解性離子狀況，以感應耦合電漿原子發射光譜儀分析鉻、銅、鎳、鉛、鋅等重金屬含量，而後探討2種法之差異因素及相關性。研究結果顯示以XRF與王水消化法比較八大重金屬含量的相關性，農地樣品砷、鉻、銅、鎳、鉛、鋅含量XRF篩測值皆與王水消化法分析值具有高度的相關性，相關係數甲區砷為R2=0.97473、乙區砷為R2=0.92438、甲區鉻為R2=0.98356、乙區鉻為R2=0.85479、甲區銅為R2=0.99753、乙區銅為R2=0.99466、甲區鎳為R2=0.99448、乙區鎳為R2=0.99044、甲區鉛為R2=0.99705、乙區鉛為R2=0.85402、甲區鋅為R2=0.99819、乙區鋅為R2=0.98152，顯示扣除XRF偵測極限的限制後，兩區域農地土壤樣品XRF篩測值與王水消化法檢測值皆呈現高度的相關性，實務上可以減少需分析樣品數量，降低檢測分析成本及縮短場址評估時間。

關鍵字

王水消化法；重金屬； X-射線螢光光譜儀

並列摘要

Currently, aqua regia digestion is used as a standard method for the total analysis of heavy metals in soil. This method yields relatively accurate measurement values and heavy metal content but is costly and time consuming. In recent years, X-ray fluorescence spectrometry (XRF) has been employed for rapid identification of heavy metal pollution at soil sites. This method is less expensive and requires less time than aqua regia digestion. XRF can be used to immediately determine the approximate concentration of pollutants onsite. To determine the reliability and accuracy of using XRF to for heavy metal detection in soil, this study collected soil samples from Areas A and B in Taiwan. The soil samples were analyzed using XRF onsite and then underwent pretreatment. After passing the soil through 10-mesh and 100-mesh sieves, the metal elements to be analyzed were dissolved into ions by using aqua regia digestion, and inductively coupled plasma atomic emission spectrometry was used to analyze the content of heavy metals including chromium, copper, nickel, lead, and zinc. Subsequently, the differences and correlations between the two methods were identified. The results showed that the arsenic, chromium, copper, nickel, lead, and zinc content determined using XRF was highly correlated with that determined using aqua regia digestion. For Areas A and B, the correlation coefficients were respectively as follows: R2 = 0.97473 and 0.92438 for arsenic, R2 = 0.98356 and 0.85479 for chromium, R2 = 0.99753 and 0.99466 for copper, R2 = 0.99448 and 0.99044 for nickel, R2 = 0.99705 and 0.85402 for lead, and R2 = 0.99819 and 0.98152 for zinc. After removing the detection limitations of XRF, the heavy metal content determined using XRF on agricultural soil samples from Areas A and B was highly correlated with that obtained using aqua regia digestion. In practice, the number of samples can be reduced to lower the cost of testing and analysis and to shorten the on-site assessment time.