建立了一种利用Dionex ICS-90型离子色谱仪同时测定雪冰中低分子有机酸和无机阴离子的新方法.采用Ion Pac AS11-HC 4mm高容量阴离子分离柱,进样量为800μl,RFC-30型试剂控制器控制EGC淋洗液发生器在线产生不同浓度的KOH淋洗液作梯度淋洗,在31min内可同时分离检测出F-、CH3CH(OH)COO-、CH3COO-、HCOO-、Cl-、NO2-、NO3-、SO42-、(COO)22-、PO43-等十余种组分.对低分子有机酸的检测限为0.7-22.8 ng g-1,对无机阴离子的检测限为0.2-22.4 ng g-1.应用此方法对天山雪冰样品中低分子有机酸和无机阴离子进行了测定.
Three cascade reservoirs,built in different periods of time in the Wujiang drainage basin,were inves-tigated in this study.Samples were taken at the surface and also at 20,40,60,80 m depths in front of the dams in April,July,October of 2006 and January of 2007.Chemical parameters were calculated and the concentrations of dissolved inorganic carbon DIC and its isotopic composition(δ13CDIC) were de-termined.In surface waters,the δ13CDIC values are high in summer and autumn and low in winter and spring,while the DIC concentrations are relatively low in summer and autumn and relatively high in winter and spring.In the water column,the DIC concentrations increase while δ13CDIC values decrease with water depth.DIC in various reservoirs is significantly different in isotopic composition from that in natural rivers,but is close to that in natural lakes.In addition,in surface waters,the δ13CDIC values tend to become lower whereas the nutrition level tends to become higher with increasing age of the reser-voirs.The conclusion is that after dam blocking,changes took place in the hydrochemical properties of river water,and the impounding rivers developed toward lakes and swamps.In addition,differentiation in DIC isotopic composition may be used to some extent to trace the evolution process of a reservoir.
