珠海市大气环境中氡浓度的测定

采用固体径迹探测器累积氡测定方法对珠海市不同地质背景、不同的建筑风格的房室内室、外地面水平氡浓度进行了测定。结果表明,珠海市室内、外空气中氡浓度的平均值分别为：１６４。２Ｂｑ／ｍ＾３和７５．２Ｂｑ／ｍ＾３,居全国各大城市之首,仅次于我国的个旧地区,但大多数住房室内氡浓度都低２００Ｂｑ／ｍ＾３。研究发现秋冬季的室外氡浓度高于春夏季的室外氡浓度。而室内氡浓度的浓度的变化情况则相反,春夏季高于秋冬季,室     

Characteristics of airborne particles inside southern California museums

The concentrations and chemical composition of suspended particulate matter were measured in both the fine and total size modes inside and outside five southern California museums over summer and winter periods. The seasonally averaged indoor/outdoor ratios for particulate matter mass concentrations ranged from 0.16 to 0.96 for fine particles and from 0.06 to 0.53 for coarse particles, with the lower values observed for buildings with sophisticated ventilation systems which include filters for particulate matter removal. Museums with deliberate particle filtration systems showed indoor fine particle concentrations generally averaging less than 10 μg m⁻³. One museum with no environmental control system showed indoor fine particle concentrations averaging nearly 60 μg m⁻³ in winter and coarse particle concentrations in the 30–40 μg m⁻³ range. Analyses of indoor vs outdoor concentrations of major chemical species indicated that indoor sources of organic matter may exist at all sites, but that none of the other measured species appear to have major indoor sources at the museums studied. Significant fractions of the dark-colored fine elemental (black) carbon and soil dust particles present in outdoor air are able to penetrate to the indoor atmosphere of the museums studied, and may constitute a soiling hazard to works of art displayed in museums.     

贵阳地铁1号线氡浓度特征及其潜在健康效应评估

地铁轨道交通逐渐成为人们日常出行的首选,但作为较封闭的地下空间环境易导致氡积聚,对于工作人员和乘客存在潜在的电离辐射暴露风险,有必要进行监测评估。贵阳地铁1号线于2018年12月开通运营,所穿越地层主要为碳酸盐岩,该地层风化过程中常常产生氡异常,尤需引起关注。本研究利用RAD-7电子测氡仪,分别于2020年7月29日和2021年1月7日对该地铁全线20个地下站点及车厢中空气氡浓度进行监测,分析其时空变化特征及主要影响因素,估算人员暴露剂量,评估潜在健康效应。结果表明：贵阳地铁1号线氡浓度水平为9.6～257.5 Bq/m³,均值为38.9 Bq/m³,高于我国主要城市地铁氡平均值(28.9 Bq/m³),低于国外平均值(105.2 Bq/m³);且不同站点存在较大差异,整体上氡浓度夏季低于冬季。计算发现,站内工作人员因氡及其子体暴露导致的有效剂量为0.28 mSv/a,小于天然背景辐射值(约为2.4 mSv/a),属于低剂量辐射范围,不存在健康风险。     

Use of natural basement ventilation to control radon in single family dwellings

Natural basement ventilation has always been recommended as a means of reducing radon levels in houses. However, its efficacy has never been documented. In these experiments, natural ventilation has for the first time been studied systematically in two research houses during both the summer cooling season and the winter heating season. Ventilation rates, environmental and house operating parameters, as well as radon levels, have been monitored.It can be definitively concluded from radon entry rate calculations that natural ventilation can reduce radon levels two ways. The first is by simple dilution. The second is by reducing basement depressurization and thus the amount of radon-contaminated soil gas drawn into the structure.Therefore, basement ventilation can be an effective mitigation strategy under some circumstances. It might be especially useful in houses with low radon concentrations (of the order of 370 Bq m ⁻¹) or those with low levels and which cannot be mitigated cost-effectively with conventional technology.     

Dependency of radon entry on pressure difference

Radon levels, ventilation rate and pressure differences were monitored continuously in four apartment houses with different ventilation systems. Two of them were ventilated by mechanical exhaust, one by mechanical supply and exhaust, and one by natural ventilation. The two-storey houses were constructed from concrete elements on a slab and located on a gravel esker. It was surprising to find that increasing the ventilation rate increased levels of radon in the apartments. Increased ventilation caused increased outdoor-indoor pressure difference, which in turn increased the entry rate of radon and counteracted the diluting effect of ventilation. The increase was significant when the outdoor-indoor pressure difference exceeded 5 Pa. Especially in the houses with mechanical exhaust ventilation the pressure difference was the most important factor of radon entry rate, and contributed up to several hundred Bq m⁻³ h⁻¹.     

On the spatial and temporal variations in atmospheric concentrations of hexachlorobenzene and hexachlorocyclohexane isomers at several locations in the province of Ontario,Canada

Hexachlorobenzene (HCB), as well as α- and γ-hexachlorocyclohexane (HCH) have been measured at seven sites in Ontario, Canada during the years 1985–1989. While two of the locations were close to a suspected source of the organochlorines, five were sites that reflected the non-urban airshed loadings which are considered to be regionally representative of the Great Lakes. At the non-urban locations, the γ-HCH (lindane) and α-HCH concentrations ranged from 15 to 190 pg m⁻³ (mean of 47 pg m⁻³) and 50 to 660 pg m⁻³ (mean of 240 pg m⁻³), respectively. The HCB concentrations varied from 20 to 310 pg m⁻³ (mean of 94 pg m⁻³). At the suspected source locations, the α:γ HCH ratio was less than unity while at locations distant from known or suspected sources, the α:γ ratio was usually greater than 7. At the non-urban locations, the highest concentrations of the α- and γ-HCH isomers were observed during the summer and the lowest concentrations were seen during the winter. The concentration of HCB, however, remained relatively constant throughout the year.     

Spatial and temporal patterns in nitrogen dioxide concentrations in a hot desert region

This paper reports seasonal and spatial variations in the ambient air concentration of nitrogen dioxide throughout the State of Bahrain, from February to December 1992. Monitoring sites were chosen to include urban areas with high traffic density, suburban areas with low traffic density, commercial and industrial areas. Correlations between meteorological parameters and mean NO₂ concentrations were analysed, and NO₂ levels were only significantly correlated with temperature (r = 0.63). Only February, a winter month, showed a significantly lower concentration of NO₂ with an overall mean value of 23 μgm⁻³, whereas in August, a summer month, it was 33 μgm⁻³. The results revealed that in a hot region like Bahrain, NO₂ concentrations do not show significant monthly variations. Also summer-averaged NO₂ values exceeded corresponding spring and winter values. In cold regions opposite patterns were observed. Moreover, the results revealed significant spatial variations in NO₂ concentrations. In suburban areas with low traffic density, the overall mean NO₂ level was 15, with a range of 12–17 μg m⁻³, while in urban areas with high traffic density, the overall mean value was 52 with a range of 44–60 μg m⁻³. The mean NO₂ value in industrial sites with low traffic density was 21 with a range of 14–27 μg m⁻³, whereas in the same areas near major roads, it was 32 with a range of 31–32 μg m⁻³. These results indicate that automobiles exhaust are the dominant source of NO₂ in Bahrain. The highest NO₂ levels were found in roads with high traffic density, which are narrow, with several traffic lights and roundabouts, suggesting the effect of road geometry on NO₂ levels.     

Seasonal trend of ambient PCDD/Fs in Tianjin City, northern China using active sampling strategy

The spatial concentrations, seasonal trends, profiles and congener pairs of ambient polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were investigated within a seasonally active sampling scheme during Jun 2008 and Jan 2009 in Tianjin City, northern China. The PCDD/F concentrations ranged 14.2-172 fg I-TEQ/m³ (average 69.3 fg I-TEQ/m³) in summer and (89.8-1.01) × 10³ fg I-TEQ/m³ (average 509 fg I-TEQ/m³) in winter, respectively, except for the E-waste dismantling site where much higher values were observed (1.04 × 10³ fg I-TEQ/m³ in summer and 7.123 × 10³ fg I-TEQ/m³ in winter). The results indicated a significantly seasonal trend with higher TEQ values in winter as compared with summer, which could be related to increased emission sources and seasonal variations of the atmospheric boundary layer height. 2,3,4,7,8-PeCDF was the dominant contributor to the total PCDD/F toxic equivalents, and 2,3,7,8-TCDD was detected at almost all the sampling sites in winter. Most of the similarly substituted PCDD/F congener pairs exhibited high correlations, suggesting that they might have similar environmental fate or sources. But different seasonal and spatial distributions of PCDD/F concentrations indicated that the emission sources might be intermittent.     

Air pollutant concentrations in Varanasi,India

This study reports the diurnal patterns in the concentrations of ozone (O₃), nitrogen dioxide (NO₂), sulphur dioxide (SO₂) and total suspended particulate matter (TSP) in the urban atmosphere of Varanasi city in India during 1989. The city was divided into five zones and three monitoring stations were selected in each zone.Ambient concentrations of NO₂ and SO₂ were maximum during winter but ozone and TSP concentrations were highest during summer. The measured maximum concentrations (2-h average) were 150 and 231 μg m⁻³ (0.078 and 0.086 ppm) for NO₂ and SO₂, respectively, for the winter season. Ozone and TSP concentrations reached a maximum of 160 (0.08 ppm) and 733 μg m⁻³, respectively, in the summer. NO₂ and SO₂ concentrations peaked in the morning and evening. Peak concentrations of O₃ occurred in the afternoon, generally between noon and 4 p.m. Maximum concentrations of O₃, NO₂, SO₂ and TSP were measured in zones I and II, and minimum in zone V.     

The personal,indoor and outdoor concentrations of PM-10 measured in an industrial community during the winter

The concentrations of PM-10 were measured for 2 weeks in the winter of 1988 as part of the Total Human Environmental Exposure Study (THEES). Samples were taken simultaneously in a small city, Phillipsburg, NJ for outdoor and indoor microenvironments, and with personal monitors on non-smokers. There were four outdoor sites, eight indoor sites and fourteen individuals wearing personal monitors. The mean concentrations were 66, 48 and 42 μg m⁻³ for the personal, outdoor and indoor sites, respectively, with the personal samplers having 8.8% of the 24h averages above 150 μg m⁻³. The higher outdoor averages with respect to indoors were suspected to be related to more prevalent outdoor sources of coarse particles < 10 μm in diameter, and the lack of residential smokers to contribute to the indoor respirable subfraction. There was one day during the period when all the outdoor sites exceeded the 24 h PM-10 standard. Increased outdoor levels were also reflected in elevated indoor samples and the personal samples on that day. These would be a result of direct outdoor exposures and the penetration of outdoor PM-10 to the indoors.     

Chlorinated organic compounds in the troposphere over the western North Atlantic Ocean measured by aircraft

Results of 32 individual flights during 1985, 1986 and 1988 using a King Air research aircraft over the western North Atlantic Ocean and the Adirondack Mountains are presented. Measurements were made for selected trace organic compounds including α- and γ-isomers of hexachlorocyclohexane (HCH), the summed isomers of α- and γ-chlordane, dieldrin and polychlorinated biphenyls (PCBs). The concentrations of compounds at altitudes of 300–10,000 ft indicate that these compounds were well mixed in the atmosphere and that for the most part, ground-level and higher-altitude concentrations were similar in magnitude. There was a high degree of variability due to time, meteorological events and location. Concentrations over the Adirondack Mountains in 1985 were the highest measured with means of 0.198 ng m⁻³ for HCB, 0.388 ng m⁻³ for α-HCH, 0.509 ng m⁻³ for γ-HCH, 0.340 ng m⁻³ for dieldrin, 0.480 ng m⁻³ for chlordane and 0.951 ng m⁻³ for total PCBs. Concentrations over the western North Atlantic south-east of Bermuda in summer 1988 wer lower, with means of 0.093 ng m⁻³ for HCB, 0.142 ng m⁻³ for α-HCH, 0.012 ng m⁻³ for γ-HCH, 0.016 ng m⁻³ for dieldrin 0.020 ng m⁻³ for chlordane and 0.600 ng m⁻³ for PCBs. During 1988 concentrations of most of the compounds were similar in the atmosphere of the coastal zone, 50–100 km off the U.S., to those measured near Bermuda. Chlordane, and to a lesser extent dieldrin, showed a decrease in concentration away from North America.     

北京地区室内氡浓度研究

本文报道了北京地区14种代表性建筑物室内的氡浓度,并对北京地区室内氡源的相对影响进行了分析。结果表明,房屋下面的地基土壤和建筑材料是室内氡的主要来源,占室内氡全部来源的70—80％;地面和建筑物表面的裂隙、孔道是氡气进入室内的主要途径;生活用水、民用燃煤和燃气对室内氡的影响不到2％。北京地区地面建筑室内平均氡浓度为30Bq/m~3,所致居民年有效剂量当量为0.93mSv。地下建筑中室内平均氡浓厦为35Bq/m~3,所致居民年有效剂量当量为1.3mSv。     

闽北570铀矿区周围大气环境氡浓度水平研究

对闽北570铀矿区的大气氡环境地球化学进行了研究。矿区废渣和坑道口释放出来的氡气对周围大气形成了一定的氡污染,特别是在矿区周围0.5～1km范围内的污染较严重。但是空气中的氡污染随着离矿区的距离增大而迅速减弱,矿区周围居民室内氡的浓度较高,是福建省室内氡浓度平均值的1～8倍左右。在进行调查的28个居室中,有6个(占21%)居室内氡浓度超过我国住房内氡浓度控制标准GB/T16146-1995中已建住房的室内氡浓度上限值(200Bq/m3)和国际辐射防护委员会制定的200Bq/m3的上限值。居室中氡浓度的升高,除了受矿区释放出来的氡污染外,还因为本地区属高本底辐射区,房基下的土壤、岩石和建筑材料中的铀、镭等放射性元素的含量高,其放射性衰变产生的氡释放出来进入室内。     

基于后向轨迹对城市大气中二噁英长距离迁移来源的探讨

通过对广州某商住区大气中二噁英的季节性监测,结合后向轨迹的计算,对大气中PCDD/Fs的浓度及其长距离迁移来源进行分析.结果表明:大气中二噁英浓度有季节性变化特点,其趋势为冬季(14.4 pg·m^-3)>秋季(10.0 pg·m^-3)>春季(5.54 pg·m^-3)>夏季(3.88 pg·m^-3).同时,大气中PCDD/Fs单体特征也具有季节性特点,秋冬季节七氯代、八氯代PCDD/Fs百分比高于春秋两季,春夏两季低氯代单体百分比含量高于秋冬两季.追溯采样期间该城市大气的后向轨迹,发现秋冬两季到达广州的气团主要经过湖南、湖北和江西等北方或东北方的内陆省份,而春夏两季到达广州的气团主要经过我国东海和南海海域上空.而这种变化很可能是造成广州大气中二噁英浓度季节性变化的主要原因.     

Radon at the Mauna Loa observatory: Transport from distant continents

Continuous measurements of radon have been made at an altitude of 3400 m at the Mauna Loa Observatory, Hawaii. Concentrations ranged from about 20 to more than 700 mBq m⁻³. These were similar to values at remote Macquarie I., some 2000 km south of Australia in the Southern Ocean. At Mauna Loa, the radon concentrations could usually be separated into free tropospheric and island influenced categories on the basis of local meteorological observations. On one occasion a long range transport event from Asia brought relatively high radon concentrations to Mauna Loa and persisted for several days. The Asian origin of this event was supported by wind trajectories. This measurement program demonstrates the value of radon data in evaluating air transport models and the influence of transport from distant continents on baseline atmospheric measurements.     

A chemical characterization of atmospheric aerosol in Sapporo

Monthly mean chemical composition of aerosol with diameter less than 8 μm was identified in Sapporo in 1982. The mass of aerosol was made up of nine components: elemental C, organics, SO₄²⁻, NO₃⁻, NH₄⁺, Cl⁻, Na⁺, soil particles and water. The concentrations of carbonaceous particles (elemental C and organics) was relatively high (12.7–16.0μ m⁻³) in autumn and winter (October–February) due to emission from domestic heating and comprised 36–41% of total aerosol mass. Higher concentration of soil particles was observed in spring (March–May) (9.7–13.1 μg m⁻³) and comprised 22–29% of total aerosol mass due to suspension by strong wind. On the other hand, the concentration of excess SO₄²⁻ (non-sea salt SO₄²⁻), which ranged from 2.6–5.2 μg m⁻³, did not change remarkably with season, and the fraction of excess sulfate increased to 21% in summer (July–August) probably due to photochemical transformation from SO₂. Nitrate concentration was far less than that of SO₄²⁻ throughout the year in Sapporo.     

个旧地区环境中氡水平及其与地质特点的关系

为了研究个旧地区环境中氡的浓度及分布、运移规律,采用ＳＳＮＴＤ方法,于１９９０－１９９２年间在个旧地区进行了氡的环境地质野外考察和土壤、居室内布点监测,共获４７９个数据。结果表明,尽管在个旧地区未发现铀、钍矿物,土壤氡水平普遍超过世界地壳土壤氡水平均值。居民室内氡水平均值高达４７１．９Ｂｑ·ｍ－３,远高于我国部分省、市近年来所测氡水平值,位于断裂带的居室氡水平高于远离断裂带的居室。个旧地区室内氡夏季高,冬季低,与一些国内、外有关报道结果相反。氡水平与楼层高度呈正相关,顶层为底层的２．７０倍。调查结果可能与个旧地区的环境地质因素有关。建议采取远离地质断裂带建房和防止上升气流逸入室内的防氡辐射进而防癌的措施。     

Seasonal variation of methanesulfonic acid in precipitation at Amsterdam island in the southern Indian Ocean

A 29-month record of methanesulfonate (MSA) concentration in 103 rainwater samples has been performed at Amsterdam Island in the southern Indian Ocean. Rain water MSA concentrations range from 0.008 to 1.150 μeql⁻¹ with a mean value of 0.187 ± 0.054 μeql⁻¹. A strong seasonal variation in rain water MSA concentration was found with a minimum in winter and a maximum in summer, similar to that observed for atmospheric DMS concentrations measured during the same period. The annual average MSA wet deposition during the studied period was 0.51 μeq m⁻² d⁻¹ which represents roughly 20% of the annual average DMS flux.     

The assessment of personal exposure to nitrogen dioxide in epidemiological studies

Personal and indoor exposure to nitrogen dioxide (NO₂ were studied in a population of housewives and children. Personal exposure, indoor concentrations and peak exposures were measured using Palmes' diffusion tubes during three measurement periods of 1 week within 1 year. Very high peak concentrations were found in the kitchens (up to 2000 μg m⁻³).Three different estimates of personal exposure were constructed using indoor concentrations and time budget data. All three were found to be closely associated with measured personal exposure.The variability over time of personal and indoor concentrations, and of the three exposure estimates was investigated in a one-way analysis of variance. The within-location or within-subject variances of indoor concentrations and estimated personal exposures were found to be smaller, relative to the between-location or between-subject variances, than the within-subject variance of measured personal concentrations. The close association between measured indoor concentrations (or exposure estimates based on indoor concentrations) and measured personal exposure suggests that measuring indoor concentrations of nitrogen dioxide in the home is sufficient to estimate personal exposure accurately.Short term peak concentrations were found to be only weakly associated with indoor NO₂ sources and weekly average indoor NO₂ concentrations. Repeated exposure to short term peak concentrations has been suggested that diffusion type measurements of personal and indoor exposure to NO₂, which are widely used suggests that diffusion type measurements of personal and indoor exposure to NO₂, which are widely used in epidemiologic studies, may not adequately reflect the most biologically relevant exposure.     

地下工程中空气离子环境和氡害

近年来国内外大量研究资料表明:环境中空气离子和氡是两个与人舒适感及人体健康密切相关的环境因素。地下工程中空气离子和氡问题比地面室内环境更为突出。随着地下空间广为开发利用,如何改善地下工程中空气离子环境及防氡害问题正在引起人们的极大关注。我们对我国五个地区的37个