氨氮是海洋沉积物中氮的最主要存在形式之一,是海洋沉积物-海水界面间物质交换最为活跃的部分。当前通常利用NaCl、MgCl2或KCl等中性溶剂浸取沉积物中氨氮的方法,仅仅是测定其中的部分氨氮。本文先用0.1 mol/L盐酸将沉积物中的氨氮较为充分地浸取出来,然后用次溴酸盐氧化法测定氨氮。在大量实验的基础上,确定了最佳分析条件,包括次溴酸溶液的碱度及其浓度、显色剂磺胺的用量和显色酸度,获得了较高的精密度和准确度。确立的方法可以较为全面地提取出沉积物中的氨氮,适用于海洋沉积物中氨氮的测定。
Ammonia-N is one of the important compositions of marine sediment and the most active component at the sediment-water interface.The routine method uses NaCl,MgCl or KCl and other neutral solvents as extractants.However,only part of ammonia-N in sediments can be determined by this method.A new method to determine ammonia-N in sediment is presented in this paper.Ammonia-N in sediment was extracted by the 0.1 mol/L HCl,then determined by hypo-bromate oxidation.Based on a large number of experiments,the optimal measurement conditions were selected,which included hypo-bromic acid concentration,NaOH concentration in hypo-bromic acid solution,acidity for chromogenic reaction and dosage for sulfanilamide.Almost all of the ammonia-N in marine sediments can be extracted by this new method with better precision and accuracy than alternative methods.