Trebs inorganic gases and aerosol8/15/2023 (2) Pollution episodes often occur in Northeast China, especially during the winter period. The water-soluble ions show clear diurnal variation with the high concentration around 09:00 for SO 4 2−, NH 4 +, and Cl − which is consistent with the high heating grade index. In terms of ionic equilibrium, the total concentration of negative ions was slightly greater than that of positive ions and the difference was 3.1% of the total ion load on average, indicating that local aerosols are mainly neutral. The contribution of TWSIs components increased during the pollution episodes, but certain differences were observed in different pollution episodes. TWSIs accounted for 32% of PM 10 mass during the entire observation period, and the contribution of TWSIs in PM 10 ranged from 33.4–43.1% in the seven pollution episodes. (1) During the entire observation period and in seven pollution episodes, SO 4 2−, NO 3 −, and NH 4 + (SNA) accounted for 84.4–93.1% of the total water-soluble ions (TWSIs). HONO exhibited a characteristic diel cycle with high mixing ratios at nighttime and was not completely depleted by photolysis during daylight hours.From January 1 to April 22, 2014, an online analyzer for monitoring aerosols and gases (MARGA) was used to measure and analyze water-soluble ions in inhalable particulate matter with a diameter less than 10 μm (PM 10) during winter-spring in Shenyang city, China. This is attributed to strong relative humidity and temperature variations between day and night as well as to changing photochemistry and stability conditions of the planetary boundary layer. Additionally, N-containing gas and aerosol species featured pronounced diel variations. During the wet season, mixing ratios decreased by nearly a factor of 3 for all compounds compared to those observed when intensive biomass burning took place. Accordingly, mixing ratios of NH 4 + exceeded those of other inorganic aerosol contributors by a factor of 4 to 10. Mixing ratios of acidic trace gases remained below 1ppb throughout the measurement period, while NH 3 levels were an order of magnitude higher. Median LOD values (3?-definition) were ?0.015 ppb for acidic trace gases and aerosol anions and ?0.118 ppb for NH 3 and aerosol NH 4 +. The limit of detection (LOD) was determined for each single data point measured during the field experiment. Overall measurement uncertainties of the ambient mixing ratios usually remained below 15%. A detailed description and verification of the inlet system for simultaneous sampling of soluble gases and aerosol compounds is presented. Measurements were made continuously using a wet-annular denuder in combination with a Steam-Jet Aerosol Collector (SJAC) followed by suitable on-line analysis. Sampling was performed from 12 September to 14 November 2002, extending from the dry season (extensive biomass burning activity), through the transition period to the wet season (background conditions). This study was conducted within the framework of LBA-SMOCC (Large Scale Biosphere Atmosphere Experiment in Amazonia Smoke Aerosols, Clouds, Rainfall and Climate). ![]() We measured the mixing ratios of ammonia (NH 3), nitric acid (HNO 3), nitrous acid (HONO), hydrochloric acid (HCl), sulfur dioxide (SO 2) and the corresponding water-soluble inorganic aerosol species, ammonium (NH 4 +), nitrate (NO 3 ?), nitrite (NO 2 ?), chloride (Cl ?) and sulfate (SO 4 2?), and their diel and seasonal variations at a pasture site in the Amazon Basin (Rondônia, Brazil).
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