武汉典型饮用水水源中典型POPs污染特征与健康风险评估

为了揭示武汉典型饮用水水源中典型持久性有机污染物(POPs)的污染特征与风险水平,采用固相萃取-气相色谱-质谱定性定量分析法,对武汉长江及其支流上18个典型集中式饮用水水源地,共26个采样点水体中多环芳烃(PAHs)、有机氯农药(OCPs)和多氯联苯(PCBs)浓度进行了检测,分析了 POPs的污染水平,并开展健康风险评估.结果表明,26个采样点均有PAHs检出,除苯并[k]荧蒽检出率为88.46％外,其他15种单体检出率均为100.00％,多环芳烃累积ρ(∑PAHs)检出范围为57.04～475.79 ng·L-1,平均值为173.86 ng·L-1.PAHs污染程度总体较低,PAHs主要以中低环芳烃为主,来源于以石油源为主的混合源.共有8种OCPs被检出,(∑OCPs)范围为ND-4.57 ng.L-1,平均值为0.78 ng·L-1,OCPs浓度水平相对较低.共有24种PCBs被检出,ρ(∑PCBs)范围为ND-77.49 ng·L-1,平均值为9.88 ng·L-1,PCBs主要以不易降解的高氯联苯为主,部分点位PCBs浓度超过我国地表水环境质量标准限值,HeptaCBs-180物质需要引起持续关注.健康风险评估结果显示,研究区域内PAHs和PCBs的致癌风险指数均处于10-6～10-4,对人体可能产生潜在的致癌风险;OCPs和PCBs的非致癌风险指数均小于1,不会对人体产生非致癌风险.     

祁连山北坡中段降水稳定同位素特征及水汽来源分析

依据祁连山北坡中段8个站点的降水样品,结合同期气象数据,从降水同位素特征、影响因素以及水汽来源等方面进行分析,结果表明:①研究区降水稳定同位素季节变化明显,表现为夏半年富集,冬半年贫化的特征;在空间尺度上δ18O值随海拔的升高而减小,年降水δ18O的海拔效应为-0. 19‰/100 m;②各站点的局地大气降水线的斜率和截距表现为随海拔的增加而增加的趋势,表明2 000 m以上的高海拔山区受到更强烈的局地再循环水汽的影响;③研究区降水中稳定同位素温度效应显著,δ18O的温度效应为0. 64‰,且仅在夏季存在微弱的降水量效应;④研究区云下蒸发作用显著.在5、6、7和8月,研究区降水δ18O的平均雨滴蒸发率分别为23%、11%、12%和16%,云下蒸发富集率46%、27%、38%和32%;⑤在夏季连续降雨条件下,研究区降水的水汽来源主要为西风水汽,同时受到局地蒸发水汽的影响.本研究结果有助于进一步了解内陆河水文循环过程,为进一步开展干旱区同位素水文研究奠定基础.     

Modeling study on the roles of the deposition and transport of PM2.5 in air quality changes over central-eastern China

The role of PM_2.5 (particles with aerodynamic diameters ≤ 2.5 µm) deposition in air quality changes over China remains unclear. By using the three-year (2013, 2015, and 2017) simulation results of the WRF/CUACE v1.0 model from a previous work (Zhang et al., 2021), a non-linear relationship between the deposition of PM_2.5 and anthropogenic emissions over central-eastern China in cold seasons as well as in different life stages of haze events was unraveled. PM_2.5 deposition is spatially distributed differently from PM_2.5 concentrations and anthropogenic emissions over China. The North China Plain (NCP) is typically characterized by higher anthropogenic emissions compared to southern China, such as the middle-low reaches of Yangtze River (MLYR), which includes parts of the Yangtze River Delta and the Midwest. However, PM_2.5 deposition in the NCP is significantly lower than that in the MLYR region, suggesting that in addition to meteorology and emissions, lower deposition is another important factor in the increase in haze levels. Regional transport of pollution in central-eastern China acts as a moderator of pollution levels in different regions, for example by bringing pollution from the NCP to the MLYR region in cold seasons. It was found that in typical haze events the deposition flux of PM_2.5 during the removal stages is substantially higher than that in accumulation stages, with most of the PM_2.5 being transported southward and deposited to the MLYR and Sichuan Basin region, corresponding to a latitude range of about 24°N-31°N.     

长江三角洲地区CO2浓度本底特征及来源分析

二氧化碳(CO₂)是引起全球变暖的最主要的温室气体(GHGs),直接观测大气CO₂浓度对于研究人类活动和自然活动对大气温室气体的贡献至关重要,而在多个高度上观测大气CO₂浓度则有助于明晰CO₂浓度的时空变化规律,确定其影响机制.本文利用临安区域大气本底站2018-12—2020-11不同高度(距地面21 m、53 m)处的CO₂在线观测数据,结合日变化及地面风的影响,对观测数据进行筛分,采用HYSPLIT后向轨迹模型和潜在源贡献因子法,初步探讨气象因素以及大气远距离传输对长江三角洲地区大气CO₂浓度的影响.结果表明,临安站高低层大气CO₂日变化呈夜间高于白天的特点;低层CO₂浓度大于高层,冬季高低层浓度差小于其他三季;日较差呈夏季>春季>秋季>冬季的特点;大气CO₂本底季节变化由于受到风向和气团传输的影响呈现出冬季>春季>秋季>夏季的特点;潜在源贡献分析得...     

近10年华北背景大气PM2.5中重金属健康风险及污染来源的变化

为探究近10年华北背景大气PM_2.5中重金属的变化特征,分别于2011年12月至2013年1月（Ⅰ期）和2019年9月至2021年11月（Ⅱ期）,在位于渤海中部的砣矶岛国家大气背景监测站各采集71个和160个PM_2.5样品,利用电感耦合等离子体质谱仪（ICP-MS）测定样品中重金属浓度,对比Ⅰ期与Ⅱ期重金属浓度、来源及健康风险.结果表明,Ⅱ期砣矶岛ρ（PM_2.5）均值为（54.06±39.71）μg ·m^-3,比Ⅰ期浓度低3.53μg ·m^-3.Ⅱ期PM_2.5中ρ（Zn）、ρ（Mn）、ρ（As）、ρ（Pb）和ρ（V）比Ⅰ期分别降低了54.53、172.63、0.8、79.06和3.81 ng ·m^-3,而ρ（Cr）、ρ（Cu）、ρ（Cd）和ρ（Ni）分别升高了2.01、5.42、3.03和3.55 ng ·m^-3.PMF结果表明,Ⅱ期污染源贡献率大小为：工业排放源（32.32%）>燃煤源（27.47%）>机动车排放（23.70%）>船舶排放（9.69%）>扬尘源（6.83%）,与Ⅰ期相比,扬尘源和船舶排放源对砣矶岛PM_2.5中金属的贡献率分别降低20.73%和8.83%,燃煤源和工业排放的贡献率分别增加2.50%和13.52%.Ⅱ期重金属总致癌风险增加,主要以Cr和Cd的贡献为主,总非致癌风险降低,以Mn贡献为主.因此,在大气污染治理进程中要进一步加强对Cr、Cd和Mn等重金属的污染源的管控.     

福州市区冬春季PM2.5污染特征与来源差异性分析

基于福州市区2015年2月—2016年1月间的大气PM_(2.5)监测数据,综合运用HYSPLIT后向轨迹模式、潜在源贡献因子法(WPSCF)与浓度权重轨迹分析(WCWT)等方法,探讨了福州市区冬、春季PM_(2.5)污染特征和典型污染过程成因,总结了气象因子和污染来源的季节性差异.研究期间,冬、春季是福州市区PM_(2.5)污染的主要季节,福州市区不同类型站点的PM_(2.5)浓度在冬、春季污染发生时均呈现出整体升高的特点,但浓度日变化却存在季节性差异,冬季无显著日变化,春季则表现为单峰单谷特征.福州市区春季主要受锋前暖区和高压后部等天气系统影响,大气扩散条件差,PM_(2.5)极易在不利的气象条件下累积,福建沿海地区是其PM_(2.5)污染的主要潜在源区;冬季污染易受高压天气系统作用,盛行偏北风,长江三角洲地区的污染物输入会对福州市区空气质量产生较大影响,长江三角洲、浙江东南沿海、福建北部是其PM_(2.5)污染的主要潜在源区.     

Insight into the critical factors determining the particle number concentrations during summer at a megacity in China

To identify the critical factors impacting the number concentration of particles with the aerodynamic diameters less than 2.5 μm(PNC_(2.5)), the continuous measurement of PNC_(2.5),chemical components in PM_(2.5), gaseous pollutants and meteorological conditions were conducted at an urban site in Tianjin in June 2015. Results indicated that the average PNC_(2.5) was 2839 ± 2430 d N/dlog Dp 1/cm~3 during the campaign. Compared to other meteorological parameters, the relative humidity(RH) had the strongest relationship with PNC_(2.5), with a Pearson's correlation coefficient of 0.53, and RH larger than 30% influenced strongly PNC_(2.5).The important influence of secondary reactions on PNC_(2.5) was inferred due to higher correlation coefficients between PNC_(2.5) and SO_4~(2-), NO_3~-, NH_4~+(r = 0.78–0.89; p 0.01) and between PNC_(2.5) and ratios that represent the conversion of nitrogen and sulfur oxides to particulate matter(r = 0.42–0.49; p 0.01). Under specific RH conditions, there were even stronger correlations between PNC_(2.5) and NO_3~-, SO_4~(2-), NH_4~+, while those between PNC_(2.5) and EC, OC were relatively weak, especially when RH exceeded 50%. Principal component analysis(PCA) and Pearson's correlation analysis indicated that secondary sources, vehicle emission and coal combustion might be major contributors to PNC_(2.5). Backward trajectory and potential source contribution function(PSCF) analysis suggested that the transport of air masses originated from these regions around Tianjin(Liaoning, Hebei, Shandong and Jiangsu) influenced critically PNC_(2.5). The north of Jiangsu, the west of Shandong, and the east of Hebei were distinguished as major potential source-areas of PNC_(2.5) by PSCF model.     

Characterizing oxygenated volatile organic compounds and their sources in rural atmospheres in China

Oxygenated volatile organic compounds(OVOCs) are important precursors and products of atmospheric secondary pollution. The sources of OVOCs, however, are still quite uncertain,especially in the atmosphere with much pollution in China. To study the sources of OVOCs in rural atmospheres, a proton transfer reaction mass spectrometry(PTR-MS) was deployed at a northern rural site(WD) and a southern rural site(YMK) in China during the summer of 2014 and 2016, respectively. The continuous observation showed that the mean concentration of TVOCs(totally 17 VOCs) measured at WD(52.4 ppbv) was far higher than that at YMK(11.1 ppbv), and the OVOCs were the most abundant at both the two sites. The diurnal variations showed that local sources of OVOCs were still prominent at WD, while regional transport influenced YMK much. The photochemical age-based parameterization method was then used to quantitatively apportion the sources of ambient OVOCs. The anthropogenic primary sources at WD and YMK contributed less(2%–16%) to each OVOC species. At both the sites, the atmospheric background had a dominant contribution(～ 50%) to acetone and formic acid, while the anthropogenic secondary formation was the main source(～ 40%) of methanol and MEK. For acetaldehyde and acetic acid, the biogenic sources were their largest source(～ 40%) at WD, while the background(39%) and anthropogenic secondary formation(42%) were their largest sources at YMK, respectively. This study reveals the complexity of sources of OVOCs in China, which urgently needs explored further.     

Tropospheric NO2 vertical column densities retrieved from ground-based MAX-DOAS measurements at Shangdianzi regional atmospheric background station in China

Ground-basedMulti-AXis Differential Optical Absorption Spectroscopy(MAX-DOAS)measurements were performed at Shangdianzi(SDZ)regional atmospheric background station in northern China from March 2009 to February 2011.The tropospheric NO_2vertical column densities(VCDs)were retrieved to investigate the background condition of the Beijing–Tianjin–Hebei developed economic circle in China.The seasonal variation of mean NO_2tropospheric VCDs(VCD_(Trop))at SDZ is apparent,with the maximum(1.3×10~(16)molec/cm~2)in February and the minimum(3.5×10~(15)molec/cm~2)in August,much lower than those observed at the Beijing city center.The average daytime diurnal variations of NO_2VCD_(Trop )are rather consistent for all four seasons,presenting the minimum at noon and the higher values in the morning and evening.The largest and lowest amplitudes of NO_2VCD_(Trop)diurnal variation appear in winter and in summer,respectively.The diurnal pattern at SDZ station is similar to those at other less polluted stations,but distinct from the ones at the urban or polluted stations.Tropospheric NO_2VCDs at SDZ are strongly dependent on the wind,with the higher values being associated with the pollution plumes from Beijing city.Tropospheric NO_2VCDs derived from ground-based MAX-DOAS at SDZ show to be well correlated with corresponding OMI(Ozone Monitoring Instrument)satellite products with a correlation coefficient R=0.88.However,the OMI observations are on average higher than MAX-DOAS NO_2VCDs by a factor of 28%,probably due to the OMI grid cell partly covering the south of SDZ which is influenced more by the pollution plumes from the urban areas.     

Seasonal variation in surface ozone and its regional characteristics at global atmosphere watch stations in China

We investigated the seasonal and spatial ozone variations in China by using three-year surface ozone observation data from the six Chinese Global Atmosphere Watch(GAW)stations and tropospheric column ozone data from satellite retrieval over the period2010–2012. It is shown that the seasonal ozone variations at these GAW stations are rather different, particularly between the western and eastern locations. Compared with western China, eastern China has lower background ozone levels. However, the Asian summer monsoon(ASM) can transport photochemical pollutants from the southern to the northern areas in eastern China, leading to a northward gradual enhancement of background ozone levels at the eastern GAW stations. Over China, the tropospheric column ozone densities peak during spring and summer in the areas that are directly and/or indirectly affected by the ASM, and the peak time lags from the south to the north in eastern China. We also investigated the regional representativeness of seasonal variations of ozone at the six Chinese GAW stations using the yearly maximum tropospheric column month as indicator.The results show that the seasonal variation characteristics of ozone revealed by the Chinese GAW stations are typical, with each station having a considerable large surrounding area with the ozone maximum occurring at the same month. Ozone variations at the GAW stations are influenced by many complex factors and their regional representativeness needs to be investigated further in a broader sense.