微波消解-ICP-AES/ICP-MS测定沉积物中23种元素的方法研究及应用

Research and application of microwave assisted digestion procedure for the determination of 23 elements in sediments by ICP-AES/ICP-MS

建立了一种硝酸-氢氟酸-硼酸微波消解沉积物、电感耦合等离子体发射光谱(ICP-AES)联合电感耦合等离子体质谱(ICP-MS)测定沉积物中23种元素(Al、Fe、K、Mg、Na、Ca、Ti、P、Ba、Mn、V、Sr、Zn、Cu、Cr、Ni、Co、Pb、U、Mo、Tl、Cd和Ag)含量的分析方法.样品经该方法消解后无需蒸干、离心、过滤等操作,既简化了操作,又提高了实验准确性.多次采用该方法消解并测定加拿大标准物质MESS-3,测定值与标准值吻合,重现性和稳定性好.用该方法对珠江广州段某站点沉积柱中元素进行分析测定,结果显示Zn、Cu、Pb和Cr的含量都远高于同区域其他研究结果,与污水处理厂污泥中重金属的含量相近,推测这些重金属主要来源于污水处理厂污泥.采用地质积累指数法对重金属的污染程度进行评价,结果表明,污染最严重的元素是Cd和Ag,其次是Cu和Zn,重金属元素污染程度顺序是Cd>Ag>Cu>Zn>Pb>Mo>Cr>Ni>U>Co>V>Tl>Fe.

Closed-vessel microwave digestion of sediments assisted by HNO3 ＋ HF ＋ H3BO3 were used to determine the recoveries of 23 elements using ICP-AES and ICP-MS, including A1, Fe, K, Mg, Na, Ca, Ti, P, Ba, Mn, V, Sr, Zn, Cu, Cr, Ni, Co, Pb, U, Mo, Tl, Cd and Ag. The elements loss and contamination were commendably decreased using this method without any evaporation, centrifugation or/and filtration. Furthermore, the accuracy of the experiments was also improved perfectly. A certified reference material （MESS-3） was digested using this method and determined using ICP-AES and ICP-MS. Calculated recoveries and repeatabilities confirmed the good performance of the procedures adopted. This method was then applied to sediment core samples obtained from the Guangzhou section of the Pearl River. The concentrations of Zn, Cu, Pb and Cr were much higher than those previous studies reported in the same region, and were close to the contents of these metals in municipal sewage sludge. Therefore, it can be concluded that the main source of these heavy metals is probably from municipal sewage sludge. Geo-accumulation index （Is^o） was used to assess the pollution degree of heavy metals. The results indicated that Cd and Ag had the highest Iseo values followed by Cu and Zn, and the pollution degree of heavy metals was in the order of Cd 〉 Ag 〉 Cu 〉 Zn 〉 Pb 〉 Mo 〉 Cr 〉 Ni 〉U 〉Co 〉V 〉Tl 〉Fe.