Temporal variation of Be concentrations in atmosphere for 8 y from 2000 at Yamagata,Japan: solar influence on the Be time series

We have been continuously observing the daily ⁷Be concentrations in surface air at Yamagata, Japan (38.25° N, 140.35° E) since 2000. The yearly profile of the ⁷Be concentration indicates the variation in galactic cosmic rays owing to solar modulation. Over 8 y, the ⁷Be concentration, cosmic neutrons, and number of sunspots varied by 37.4%, 12.2%, and 92.8%, respectively. The influence of precipitation on the ⁷Be variability was approximately 5%. Hence, the yearly ⁷Be concentration was mainly varied by the solar modulation of the ⁷Be production rates. Based on the production rates found in an EXPACS simulation, the observed variability indicates ⁷Be transport from high latitudes. The daily ⁷Be concentrations have two significant periodic components of 19 d and 36 d. The 36-d component implies a relationship between the sun's rotation and the vertical transport of air masses under quiet solar activity.     

Novel sampling methods for atmospheric semi-volatile organic compounds (SOCs) in a high altitude alpine environment

High- and low-volume active air samplers as well as bulk deposition samplers were developed to sample atmospheric SOCs under the adverse conditions of a mountain environment. Active sampling employed separate filters for different European source regions. Filters were switched depending on daily trajectory forecasts, whose accuracy was evaluated post hoc. The sampling continued on three alpine summits over five periods of four months. The prevailing trajectories varied stronger between sampling periods than between stations. The sampling equipment (active and bulk deposition) proved dependable for operation in a mountain environment, with idle times being mainly due to non-routine manipulations and connectivity.     

Deposition fluxes of PCDD/Fs in a reservoir system in northern Taiwan

In this study, polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) concentrations and depositions in ambient air, water column and sediment were measured at a coupled reservoir-watershed system in northern Taiwan. The atmospheric PCDD/F concentration measured in the vicinity of the reservoir ranged from 4.9 to 39 fg I-TEQ m⁻³ and the Asian dust storm in February accounted for the peak value, which corresponded to a total suspended particle concentration of 128 μg m⁻³. The atmospheric PCDD/F deposition ranged from 1.4 to 19 pg I-TEQ m⁻² d⁻¹, with higher deposition occurring during winter and spring (long-range transport events). During summer, when atmospheric deposition is lower, consecutive tropical cyclones (typhoons) bring heavy rainfall that enhances soil erosion and creates turbidity-driven intermediate flow. This results in significantly higher PCDD/F deposition in water column of the reservoir at 70 m water depth (179 pg I-TEQ m⁻² d⁻¹) than at 20 m (21 pg I-TEQ m⁻² d⁻¹) during typhoon event. The accumulation rate of PCDD/Fs (9.1 ng I-TEQ m⁻² y⁻¹) in the reservoir sediments (depth: 0-2 cm) was consistent with PCDD/F deposition obtained from water column (6.1 and 8.3 ng I-TEQ m⁻² y⁻¹); however, it is significantly higher when compared to the atmospheric deposition (2.0 ng I-TEQ m⁻² y⁻¹). Based on the mass balance between the measurements of atmospheric deposition and sinking particles in water column, around 54-74% of PCDD/F inputs into the reservoir were contributed by the catchment erosion during normal period. However, the PCDD/F input contributed by the enhanced catchment erosion significantly increased to 90% during intensive typhoon events.     

An improved method for Kr analysis by liquid scintillation counting and its application to atmospheric Kr determination

Atmospheric ⁸⁵Kr concentration at Fukuoka, Japan was determined by an improved ⁸⁵Kr analytical method using liquid scintillation counting (LSC). An average value of 1.54 ± 0.05 Bq m⁻³ was observed in 2008, which is about two times that measured in 1981 at Fukuoka, indicating a 29 mBq y⁻¹ rate of increase as an average for these 27 years. The analytical method developed involves collecting Kr from air using activated charcoal at liquid N₂ temperature and purifying it using He at dry ice temperature, followed by Kr separation by gas chromatography. An overall Kr recovery of 76.4 ± 8.1% was achieved when Kr was analyzed in 500-1000 l of air. The Kr isolated by gas chromatography was collected on silica gel in a quartz glass vial cooled to liquid N₂ temperature and the activity of ⁸⁵Kr was measured with a low-background LS counter. The detection limit of ⁸⁵Kr activity by the present analytical method is 0.0015 Bq at a 95% confidence level, including all propagation errors, which is equivalent with ⁸⁵Kr in 1.3 l of the present air under the analytical conditions of 72.1% counting efficiency, 0.1597 cps background count rate, and 76.4% Kr recovery.     

Transfer factors of Polonium from soil to parsley and mint

Transfer factors of ²¹⁰Po from soil to parsley and mint have been determined. Artificial polonium isotope (²⁰⁸Po) was used as a tracer to determine transfer factor of Po from soil to plant in pot experiments. Two plant growing systems were used for this study namely, an outdoor system and a sheltered system by a polyethylene tent. ²⁰⁸Po and ²¹⁰Po were determined in soil and different parts of the studied plants (stem and leaf), using alpha spectroscopy. The results have shown that there was a clear uptake of ²⁰⁸Po by roots to leaves and stems of both plants. Higher values of transfer factors using the ²¹⁰Po activity concentrations than the ²⁰⁸Po activity concentration were observed. Transfer factors of ²¹⁰Po from soil to parsley varied between 20 × 10⁻² and 50 × 10⁻² and 22 × 10⁻³ and 67 × 10⁻³ in mint, while ²⁰⁸Po transfer factors varied between 4 × 10⁻² and 12 × 10⁻² for parsley and 10 × 10⁻² and 22 × 10⁻² in mint. Transfer factors of Po were higher in those plants grown in the sheltered system than in the open system; about 75% of Po was transferred from atmosphere to parsley parts using the two systems. Ratios of transferred Po from soil to mint stem and leaf in the sheltered system were higher by 2 times from those in the open system.     

基于曲线投影动态聚类模型的大气质量监测布点研究

聚类数和聚类方法是聚类分析研究的核心,具有重要的实用价值。针对各单项大气质量监测指标的不相容问题,在投影寻踪动态聚类模型的基础上,通过引入S型曲线作为投影方式,提出了基于曲线投影动态聚类的大气质量监测布点研究新方法。从理论上讲,作为一种完全由数据驱动的方法,该模型充分体现了投影寻踪聚类的设计思想,能把最佳聚类数和对应的聚类结果的分析有机地融合在一起,具有物理意义清晰,可操作性强等特点。实例应用结果表明,通过把待研究地区大气监测点多维指标综合成一维投影指标,并利用免疫进化算法优化目标函数,模型能提供明确、客观及稳健的监测布点最佳方案,实现大气质量监测经济性和代表性的平衡。上述研究可为其它非线性、非正态高维数据分类问题开辟一条新途径。     

大气VOCs快速测定及其在环境空气污染应急溯源中的初步应用

突发性大气环境污染事件处于高发期,针对环境应急监测时效性强的特点,用便携式GC-MS快速测定大气中23种VOCs,探讨大气中VOCs测定在环境空气污染应急溯源中的应用。该方法在20.0μg/m3~3 200μg/m3范围内线性良好,按采样1 L计算,方法检出限为2.6μg/m3~9.4μg/m3,加标回收率为91.3%~103%,测定结果的RSD≤10.5%。将该方法用于突发性环境污染应急事件大气中VOCs的快速测定,通过对照企业特征污染物名录,能快速锁定污染源头。     

南京市大气微生物调查及其动态研究

调查了南京市主要功能区大气微生物中常见种类的细菌和霉菌类,研究了细菌和霉菌类的生态分级和变化规律,比较了大气微生物与大气监测指标PM10、SO2、NO2的相关性。通过分析2000年10月至2001年8月6个功能区4个季节的监测结果,得出山西路监测点微生物数量最高,并且该点微生物中是以细菌为优势种,其次是霉菌属的马丁霉菌和耐渗透压霉菌。通过生理生化试验鉴定细菌和霉菌类,得出南京市大气微生物中细菌基本以微球菌属为主,霉菌以青霉属、曲霉属为主。大气微生物数量统计结果表明,南京市主要功能区微生物总量(均值)从高到低的顺序为:山西路(商业区)>中华门(交通区)>瑞金路(居住区)>迈皋桥(工业区)>玄武湖(对照点)>草场门(文教区)。大气化学监测指标PM10、SO2、NO2分析结果也表明大气微生物的数量变化与之呈一定的正相关关系,尤其与PM10关系更为密切。     

The variation of street air levels of PAH and other mutagenic PAC in relation to regulations of traffic emissions and the impact of atmospheric processes

The occurrence of particle associated PAH and other mutagenic PAC was determined in 1996 in the street air of Copenhagen. In addition, particle extracts were tested for mutagenicity. The measurements were compared with previous measurements in 1992/1993. The levels had decreased in this period. The decrease was caused by an implementation of light diesel fuels for buses and the exchange of older petrol-driven passenger cars with catalystequipped new ones. About 65% of the reduction was caused by the application of the light diesel fuels. Under special conditions, chemical processes in the atmosphere produced many more mutagens than the direct emissions. The concentrations of S-PAC and N-PAC were 10 times lower than those of PAH, while the levels of oxy-PAH were in the same order of magnitude as those of PAH. Benzanthrone, an oxy-PAH, is proposed to be formed in the atmosphere in addition to direct emissions. Benzo(a)pyrene, often applied as an air quality criteria indicator, was photochemically degraded in the atmosphere. A strong increase in the mutagenic activities was observed to coincide with a depletion of benzo(a)pyrene.