The air condensation water (ACW) was collected using an in-situ self-assembled collector on 8 March～11 April, 2011, in Shanghai. The chemical characteristics of the samples were studied in detail, and the results were compared to those of other wet deposition in terms of inter-ion correlativity, ion concentration in relation to temporal variations. The pH values of the samples ranged from 6.1～7.2 with a volume-weighted mean pH value of 6.5, mostly exhibiting weak acidity. Both NH4+ and SO42- were the most abundant components and volume-weighted means were 139.7μeq/L and 125.7μeq/L, respectively. SO42- was the predominant acid anion. The NO2- (9.9 (μeq/L) concentration was somewhat higher than that of NO3- (9.5μeq/L) and the detection rate of NO2- was 100% in all samples. The low-volatility organic acids of MSA- (6.0μeq/L), CH3COO- (5.9μeq/L), C2O42-(3.9μeq/L) and HCOO (3.7ueq/L) accounted for 8.5% of total anions, much higher than those in Shanghai rainwaters. Ca2+ (19.2μeq/L, 4.0%) and Mg2+ (4.9μeq/L, 1.0%) were two or three orders of magnitude lower than those detected in fogwaters. The ion concentration changed more appreciably as a function of time, in close association with photochemical reaction, inversion layer in spring, and so forth.%2011年3月8日至4月11日期间利用新研制的大气冷凝水采样器收集了上海大气冷凝水样品.从冷凝水的化学组成及常见大气湿沉降的比较、冷凝水离子间的相关性、冷凝水离子浓度随时间变化等方面,分析了上海大气冷凝水的化学特性.结果表明,上海大气冷凝水pH值介于6.1～7.2,加权均值为6.5,多呈弱酸性;NH4+和SO42是含量最高的2种离子,浓度分别为139.7μeq/L和125.7μeq/L,SO42-是主要致酸离子NO-2含量为9.9μeq/L,比NO-3 (9.5μeq/L)略高,且所有冷凝水样品中NO-2检出率为100％;4种低分子量有机酸MSA-(6.0μeq/L)、CH3COO (5.9μeq/L)、C2O2-4 (3.9μeq/L)和HCOO (3.7μeq/L)占阴离子总量的8.5％,含量远高于上海雨水；Ca2+(1 9.2μeq/L,4.0％)、Mg2+(4.9μeq/L,1.0％)含量比同期雾水低2～3个数量级；冷凝水离子浓度随时间变化较大,这与光化学反应、春季逆温等有关.
展开▼
