2016—2018年长三角城市群臭氧浓度超标特征分析

对长三角地区2016—2018年臭氧浓度超标的时空特征进行分析。结果表明,2016—2018年,24个城市年O3污染评价为优的城市数量为0,O3浓度超标城市由11个增长至14个;O3超标浓度和超标天数均为2017年最严重;O3浓度超标2—11月均有出现,O3中度污染和重度污染仅在4—9月出现;O3浓度小时超标9时至次日凌晨2时均有出现,超标频率最高在14—16时;O3臭氧90百分位浓度安徽省3年年均增长率达到7.8%,O3浓度年评价超标城市由东部城市向江苏西北部和安徽省转移;O3浓度超标城市年均天数在江苏省最多,安徽省增长较快,2018年几乎与江苏省持平。     

九江市臭氧浓度特征及庐山持续高浓度成因分析

利用2014～2017年九江市环境监测站环保资料和手工采集资料分析了九江市2014～2016年O_3时空分布。结果表明:九江市O_3浓度以年均20.9%的速率增加,九江市污染物超标(轻度污染)的60 d中有17 d为臭氧超标,臭氧为首要污染物的天数占全年的26.3%,且夏季臭氧污染呈现爆发性增长趋势。庐山气象台站O_3浓度始终高于其它站点。大量的植物源VOCs排放及适当的NO_x,及庐山的半山谷环境是致使其O_3浓度维持较高的原因;较低浓度的NO,较弱的滴定作用是其无明显日变化趋势的原因。     

江津区城区大气臭氧分布特征与相关影响因素研究

基于国控环境空气质量自动监测站数据分析了2017～2018年江津区城区大气中臭氧变化规律,研究了其浓度变化特征及相关气象因子的影响。结果表明:2017年、2018年,全年中臭氧(O3～8h)作为首要污染物的天数分别为53d和27d,臭氧污染问题比较突出。江津区O3小时浓度在日、月、季均呈明显的单峰分布。从4个季节平均峰值来看,臭氧浓度由高到低的季节依次是夏季、春季、秋季和冬季。臭氧污染以本地排放为主,臭氧浓度与气象因素的关系密切,O3浓度随太阳辐照、温度增高有明显的增加趋势,高温低湿有利于臭氧的形成。     

威海市夏季臭氧浓度异常升高问题探讨

分析了2019年5月与2017年、2018年同期威海市臭氧浓度特征,利用HYSPLIT后向轨迹模型研究了威海市夏季臭氧浓度异常升高过程的气团来源及传输途径,对威海市臭氧污染成因进行了初步分析,威海市自2019年5月以来,臭氧浓度超标天数达20 d左右且出现四次污染过程。通过综合分析表明,海陆风局地环流,西部或西南部污染气团的影响,以及NOx的外来输送或区域积累是造成臭氧浓度升高的重要原因。在此基础上提出了臭氧防治的建议措施。     

肇庆市2019年空气质量月度变化特征

分析了2019年肇庆市六项主要大气污染物浓度、AQI达标率、不同污染级别、首要污染物占比等月度变化情况.结果表明:肇庆市冬春季主要以PM2.5或NO2作为首要污染物,除臭氧外的各项污染物浓度也相对较高;夏秋季首要污染物主要以臭氧为主,臭氧浓度也相对较高.4～7月份的AQI达标率较高,8～11月份超标率相对较高,且臭氧月...     

绍兴北部区域大气复合污染过程中VOCs对O_3和SOA的生成潜势研究

为了研究在大气复合污染过程中,大气挥发性有机物(VOCs)对大气臭氧(O_3)和二次有机气溶胶(SOA)的影响,在绍兴北部的大气监测国控点,使用在线自动VOC监测系统(TH-PKU300B)测量了2014~2016年期间的99种大气VOCs成分的质量浓度。结合常规的大气污染物数据和气象参数,选取2014年6月1~9日作为大气复合污染的案例进行了分析。结果表明:在复合污染期间,SOA/PM2.5的比值最高可以达到9.2%,其中,甲苯、丙酮和乙醛等对SOA贡献比较大,这说明在复合污染期间VOCs对二次生成颗粒物的贡献较为显著。同时通过臭氧生成潜势的计算,芳香烃、烯烃类、醛类物质对O_3生成的贡献较大,这些VOCs的活性组分生成的O_3叠加其它O_3生成效应,助推了高浓度的O_3污染。在严重污染期间,绍兴北部区域内大气VOCs浓度与大气雾霾有较强的相关性。控制VOCs的排放,降低VOCs的浓度,减低大气氧化性,对减少重雾霾天气有很大的帮助。     

无公害石榴生产技术

1园地选择选择背风向阳、排灌方便、土层深厚、石灰质并地疏松、富含营养的砂壤土或壤土建园。具体标准为:绝对最低温高于-17℃;≥10℃的有效积温3000℃以上;pH值6.5~7.5之间;地下水位低于1m;20cm土层内有机质含量>1.0%。海拔高度不超过800m,山地坡度以5°~10°的缓坡最好,要求     

深圳市PM_(2.5)浓度变化及污染输送特征分析

根据2015年1~12月深圳市11个大气自动监测国控站点PM_(2.5)小时浓度监测数据,结合气象站小时观测数据,采用Correl相关系数法、玫瑰图等分析了深圳市PM_(2.5)浓度的污染分布与输送迁移特征。结果显示:2015年深圳市主导风向为NNE(东北偏北风),风向频率为12.3%,全年PM_(2.5)平均浓度为29.8μg/m3,整体季节平均浓度特征均表现为冬季秋季春季夏季;PM_(2.5)与露点、能见度呈显著负相关,相关系数分别为-0.517与-0.540,与海平面气压、温度呈明显的实相关,相关系数为0.439、-0.411,与风向、风速、相对湿度为微相关;深圳吹海风时,参照年均值标准,PM_(2.5)污染发生概率为22.7%,且发生秋冬季海风型PM_(2.5)污染时PM_(2.5)平均浓度可高达50.6μg/m3。主导风型下的PM_(2.5)污染事件占全年PM_(2.5)污染事件的61.1%,且风速大于3m/s时PM_(2.5)污染发生事件占比仅为6.26%;2015年全年西北陆风、主导风、海风气团输送情景下的PM_(2.5)平均浓度分别为40.1、35.8和26.2μg/m3,冬季时西北陆风输送通道下的PM_(2.5)平均浓度整体上明显高于海风、东北偏北陆风输送通道。     

西宁市典型绿地空气中微粒物PM_(2.5)和PM_(10.0)测定与分析

利用2014年8月—2015年7月西宁市5个典型绿地空气中可吸入颗粒物PM_(2.5)和PM_(10.0)及同期气象因子监测资料,分析了可吸入颗粒物分布特征、污染水平及其与气象因子的关系。结果表明:(1)西宁市5个典型绿地空气中PM_(2.5)的平均浓度为0.034mg·m-3,低于我国日平均浓度标准(0.065mg·m-3)47.69%,PM_(10.0)为0.153mg·m-3,超出我国PM_(10.0)日平均浓度二级质量标准(0.15mg·m-3)2.00%。尤其是海湖大道、新宁广场和省委家属院PM_(10.0)超标率分别为44.00%、13.33%和6.67%,应引起大众和相关部门的高度重视;PM_(2.5)和PM_(10.0)浓度从大到小的排序为海湖大道新宁广场省委家属院麒麟湾植物园;(2)5个典型绿地空气中PM_(2.5)和PM_(10.0)的日平均浓度变化和年平均浓度变化趋势基本一致,具有区域分布特征;(3)PM_(2.5)、PM_(10.0)与温度和相对湿度呈负相关,与风速没有相关性。PM_(2.5)与PM_(10.0)之间有较好的相关性。     

气象因素对攀枝花市臭氧浓度影响研究

为探究气象因素对攀枝花市臭氧(O3)的影响,对2015年攀枝花市5个国控环境监测站和同期气象台的逐日监测数据进行了分析。结果表明:攀枝花市O3浓度受气温、相对湿度、风速等因素的综合影响,其中O3变化与气温呈正相关关系,相关性较大,与相对湿度与风速呈负相关关系,相关性较小。揭示当地政府应根据气象条件来合理管控相关企业,制定相应的防护政策,以减少O3污染带来的危害。     

大连市一次典型臭氧污染过程分析

针对2015年大连市的一次高浓度臭氧污染过程的气象条件、污染物浓度和污染气团轨迹进行了分析,探讨了该次臭氧污染过程中浓度变化规律、本地生成特征、区域传输特征及污染成因。结果表明:4月25日,臭氧达到中度污染,高温、强光照下本地光化学反应生成大量臭氧是内因,低压辐合、逆温、风速小等不利气象条件导致高浓度臭氧难以扩散是外因;4月26日,臭氧维持轻度污染,是由于前一日臭氧本底值较高,叠加白天光化学反应生成导致;4月27日,臭氧维持轻度污染,并出现凌晨持续升高的现象,这与区域输送密切相关。     

2018年冬季河北省气象条件变化对PM2.5影响研究

利用河北省2017~2018年逐日PM_2.5浓度地面观测数据和CUACE空气质量模式的PM_2.5气象条件评估指数(EMI,evaluation on meteorological condition index of PM_2.5 pollution),定量评估了2018年相比2017年河北省冬季气象条件对PM_2.5浓度的贡献,并分析了石家庄市气象条件和PM_2.5浓度的同期月变化。结果表明:与2017年相比,2018年冬季河北省气象条件不利于PM_2.5浓度的下降,其中,北部、西北部地区气象条件极为不利,使PM_2.5浓度同比上升28%~45%,不同城市的气象条件变化存在显著差异;2018年石家庄市PM_2.5年均浓度同比下降12.7%,其中气象条件使PM_2.5浓度同比下降3.1%,说明石家庄市大气污染防治减排措施对PM_2.5浓度下降贡献显著。可见,EMI指数可定量诊断和评估污染期间气象条件对PM_2.5浓度的影响。     

Response of giant sequoia canopy foliage to elevated concentrations of atmospheric ozone

We examined the physiological response of foliage in the upper third of the canopy of 125-year-old giant sequoia (Sequoiadendron giganteum Buchholz.) trees to a 61-day exposure to 0.25x, 1x, 2x or 3x ambient ozone concentration. Four branch exposure chambers, one per ozone treatment, were installed on 1-m long secondary branches of each tree at a height of 34 m. No visible symptoms of foliar ozone damage were apparent throughout the 61-day exposure period and none of the ozone treatments affected branch growth. Despite the similarity in ozone concentrations in the branch chambers within a treatment, the trees exhibited different physiological responses to increasing ozone uptake. Differences in diurnal and seasonal patterns of g(s) among the trees led to a 2-fold greater ozone uptake in tree No. 2 compared with trees Nos. 1 and 3. Tree No. 3 had significantly higher CER and g(s) at 0.25x ambient ozone than trees Nos. 1 and 2, and g(s) and CER of tree No. 3 declined with increasing ozone uptake. The y-intercept of the regression for dark respiration versus ozone uptake was significantly lower for tree No. 2 than for trees Nos. 1 and 3. In the 0.25x and 1x ozone treatments, the chlorophyll concentration of current-year foliage of trees Nos. 1 and 2 was significantly higher than that of current-year foliage of tree No. 3. Chlorophyll concentration of current-year foliage on tree No. 1 did not decline with increasing ozone uptake. In all trees, total needle water potential decreased with increasing ozone uptake, but turgor was constant. Although tree No. 2 had the greatest ozone uptake, g(s) was highest and foliar chlorophyll concentration was lowest in tree No. 3 in the 0.25x and 1x ambient atmospheric ozone treatments.     

多城市PM2.5、PM10、O3浓度与气象条件关联性的Meta分析

使用2015~2017年我国29个城市的空气污染物PM_2.5、PM₁₀、O₃浓度和气象要素(包括气压、气温、相对湿度、降水量、风速、日照时数)日数据,对每个城市空气质量变化特征与气象要素的月平均值进行了线性相关和多元回归模型分析,然后Meta分析合并相关系数和回归系数。结果表明:PM_2.5浓度与所有气象变量(除风速)呈相关、PM₁₀浓度与所有气象变量呈相关,而O₃也与所有气象变量(除相对湿度)呈相关,但O₃与气象变量的相关方向和PM_2.5、PM₁₀相反。通过对污染物浓度和气象变量的多元回归分析,21个城市的空气污染都得到较好程度的解释(R²>0.5)。同时,对影响PM_2.5、PM₁₀和O₃的主要气象因素的效应进行了合并。     

内蒙古大兴安岭林火与气象因子关系研究

基于内蒙古大兴安岭1990—2019年森林火灾历史档案和同期气象因子的数据,对该地区林火与气象因子间的相关性进行了研究。结果表明,林火发生与气象因子间的关系密切。林火发生次数随着温度的升高和降水的减少呈上升趋势;研究区日均相对湿度范围在58%~62%,火灾发生次数最多;林火发生次数与日照时数、日均温、日最高温间均呈显著正相关;过火面积与日均相对湿度间呈显著负相关,与日照时数间呈显著正相关。     

Use of a single-tree simulation model to predict effects of ozone and drought on growth of a white fir tree

A physiologically based, single-tree simulation model, TREGRO, was parameterized with existing phenological, allometric, and growth data and used to predict effects of ozone and drought on growth of a 53-year-old white fir (Abies concolor (Gord. & Glend.) Lindl. ex Hildebr.) tree following a 3-year model simulation. Multiple experimental simulations were conducted to assess the individual and interactive effects of ozone (O(3)) exposure and drought on growth of white fir. The effects of O(3) were imposed as reductions in carbon (C) assimilation of 0, 2.5, 5, 10, and 20%. Drought was imposed as 0, 10, 25, and 50% reductions in total annual precipitation. The results of the simulations were compared with the effects of O(3) on white fir seedlings grown in the presence and absence of ozone in open-top chambers and with a field survey of white fir trees subjected to a gradient of O(3). In the O(3) simulations, an O(3)-induced reduction in C assimilation of 2.5% reduced total tree biomass and branch total nonstructural carbohydrate (TNC) content by < 7%. Although quantifiable in simulation experiments, such small reductions would probably not be detectable in the field. Results from both an open-top chamber experiment and a field survey indicated that reductions in C assimilation of white fir growing in elevated O(3) were much greater than 2.5%, but were not statistically different from control values. A simulated O(3) reduction in C assimilation of >/= 10% reduced total tree biomass by 7% and branch TNC by 55%. Results from the field survey indicated that branch elongation was reduced in response to increased O(3) concentration, corroborating the simulated response of reduced C allocation to the branches of white fir. Although simulated reductions in total annual precipitation of >/= 25% reduced final tree biomass, the simulated reductions also reduced O(3) uptake and therefore reduced the O(3) response of white fir. However, a combination of low amounts of O(3) (2.5% reduction in C assimilation) and drought (25% reduction in annual precipitation) synergistically reduced C gain of white fir more than either stress individually. Our simulations predict that moderate drought (no more than a 25% reduction in total annual precipitation) may not ameliorate the response of white fir to O(3) and that moderate amounts of atmospheric O(3) and drought could be more detrimental to white fir than either stress singly.     

Trends in tropospheric ozone concentrations and forest impact metrics in Europe over the time period 2000-2014

In Europe,tropospheric ozone pollution appears as a major air quality issue,and ozone concentrations remain potentially harmful to vegetation.In this study we compared the trends of two ozone metrics widely used for forests protection in Europe,the AOT40(Accumulated Ozone over Threshold of 40 ppb) which only depends on surface air ozone concentrations,and the Phytotoxic Ozone Dose which is the accumulated ozone uptake through stomata over the growing season,and above a threshold Y of uptake(PODY).By using a chemistry transport model,we found that European-averaged ground-level ozone concentrations(-2%) and AOT40 metric(-26.5%) significantly declined from 2000 to 2014,due to successful control strategies to reduce the emission of ozone precursors in Europe since the early 1990 s.In contrast,the stomatal ozone uptake by forests increased from 17.5 to 26.6 mmol O_3 m~(-2) despite the reduction in ozone concentrations,leading to an increase of potential ozone damage on plants in Europe.In a climate change context,a biologically-sound stomatal flux-based standard(PODY) as new European legislative standard is needed.     

2020年春节期间烟花禁放对安庆市空气质量效果评估

利用2019和2020年空气质量数据,进行了春节期间烟花禁放对安庆市空气质量的效果评估。结果表明:安庆市2020年烟花禁放后,春节期间优良天气比例为87.5%,比2019年提高25%,没有出现中度污染以上等级的天气。2020年除夕及正月初一,安庆市PM₁₀及PM_2.5的峰值浓度比2019年同期分别降低了78.8%、70.5%,SO₂及NO₂略有下降。2020年春节期间,烟花燃放对PM₁₀及PM_2.5的平均贡献量比2019年分别下降了81.7%、76.4%,说明烟花禁放起到了显著的污染削峰作用。此外,2020年春节期间城区及市郊PM₁₀及PM_2.5浓度比禁燃前都有所下降,且城区的峰值浓度比市郊下降得更为显著,禁放后PM₁₀及PM_2.5质量浓度的空间差异性进一步缩小。