-
近年来中国臭氧(O3)污染问题日益突出,近地面高浓度臭氧已成为影响城市空气质量的主要污染气体[1]。高浓度臭氧会对人类健康及生态环境造成危害,如刺激鼻黏膜、呼吸道、视觉神经、损害中枢神经系统[2-5],以及破坏植物形态,影响植物生理生化功能和生长发育状态等。目前,关于臭氧的研究主要集中在前体物、气象因子、典型天气等影响因素与其的关系,浓度的监测,预测模型的建立,对植物单体及农作物产量的影响等方面。城市森林既是植物生长的载体又是人们日常康养、休闲的重要场所[6],进行林内不同垂直高度的康养活动以及建立不同高度的康养设施有利于人们更加科学合理地使用森林环境,因此对城市森林内不同垂直高度的臭氧浓度研究具有重要意义。但是,中国目前关于森林内臭氧的研究主要集中在森林背景地区,对城市森林内臭氧的研究还极为缺乏。此外,城市森林内植物有机挥发物[7-8]、太阳辐射强度[9]、气象因子[10]等在不同垂直高度的差异可能会引起林内臭氧浓度沿垂直梯度的变化。然而,现有研究还未见对城市森林内不同垂直高度臭氧浓度的研究。因此,本研究以雁荡山国家森林公园内杉木Cunninghamia lanceolata林为对象,研究春夏两季不同高度杉木林环境臭氧质量浓度变化规律,分析臭氧质量浓度与环境因子的关系,为科学开发和利用森林游憩环境,为人们合理选择游憩时间、空间提供理论依据。
-
如图 2所示:杉木林内各高度臭氧质量浓度最大8 h均值为75.40~116.35 μg·m-3。H1,H2和H3各高度差异显著(P<0.05),其中H1臭氧质量浓度最低,H3最高。这可能是由于H3处于冠层上部边界,是与对流层大气交换最为强烈的区域,一方面外源环境臭氧垂直输送的前体物最先到达H3,导致其臭氧质量浓度最高;另一方面,冠层上部光照强度及紫外辐射最强,为臭氧的生成提供了有利条件;H2处于树冠中部,冠层中部为叶片相对集中区域,且植物气孔主要分布在叶片的上下表皮[12],而气孔是臭氧进入植物体并发生毒害作用的主要通道[13],所以在H2处叶片吸收部分臭氧,其质量浓度相对较低;H1由于处于距地面1.5 m处,臭氧通过H2和H3高度处植物的吸收,到达H1的通量最少。另外,臭氧与土壤的相互作用也在一定程度上降低了H1高度的臭氧质量浓度。
-
由图 3可见:H1春夏两季差异不显著。H2和H3春夏两季差异极显著(P<0.001),且H1,H2和H3各高度从春季到夏季分别下降了108.52%,139.02%和241.70%。其原因可能是由于远距离输送和对流层向下传输有关:一方面温州市区春季背景值高出夏季11.61%,因此受温州市人为源输送影响,春季臭氧质量浓度较高;另一方面该研究区受东亚季风环流系统的影响[14],春季光化学反应产生的高体积分数臭氧,随西风带向东输送,同时夏季风侵入带来低臭氧体积分数的海洋性气团[11, 15]。
春夏两季H1,H2和H3臭氧质量浓度日均值均差异显著(P<0.05)。春季H1,H2和H3臭氧浓度为57.11~103.12 μg·m-3,H1最低,H2次之,H3最高;夏季H1,H2和H3臭氧质量浓度为39.64~63.21 μg·m-3,次序与春季相同。虽然林内春夏两季臭氧质量浓度差异较大,但H1,H2和H3臭氧质量浓度变化具有一致性,可能是由于3种高度的光照强度不同,H3处于林冠上部,光强最强,且冠层上部叶片截留太阳总辐射多,会导致最终进入林下光能减少[16],所以H1处光照强度最弱。与此同时,林内辐射通量也间接影响林内温度,导致H1,H2和H3处的温度差异。那么假设在相同质量浓度臭氧前体物水平输送入林内时,H3生成臭氧的光化学反应最为强烈,致使其臭氧质量浓度升高。
-
总体来讲,春夏两季H1,H2和H3臭氧质量浓度呈单峰型变化,白天高,夜间低,但各季节H1,H2和H3出现峰值和低谷值的时间存在差异(图 4)。与夏季相比春季臭氧质量浓度昼夜变幅较大。具体为春季峰值出现于13:00-15:00,H1~H3分别达105.63,131.42和145.23 μg·m-3,其中H2和H3峰值比H1提前2 h,低谷值分别出现于5:00(23.01 μg·m-3),21:00(32.14 μg·m-3)和23:00(70.31 μg·m-3);夏季H1,H2和H3峰值均出现在11:00,依次为81.11,104.60和119.04 μg·m-3,低谷值分别出现于5:00(15.24 μg·m-3),7:00(20.55 μg·m-3,34.52 μg·m-3)。
从同一季节H1,H2和H3臭氧质量浓度日变化曲线来看,各垂直高度的小时均值存在一定差异,除7:00外,各时段均为H1<H2<H3。经方差分析,春夏两季各时间段臭氧质量浓度差异不显著。这一现象的成因可能是杉木林内小气候相对稳定,各高度臭氧质量浓度小时均值差异相对稳定。
由日最大8 h质量浓度(11:00-17:00时)均值可知,春季H1,H2和H3处日最大8 h均值依次为86.72,113.61和135.37 μg·m-3;夏季H1,H2和H3处日最大8 h均值依次为64.08,81.88和97.34 μg·m-3。各季节日最大8 h均值不仅达到国家一级标准160 μg·m-3,且春季小时均值分别低于国家标准18.19%~84.50%,夏季低于国家标准64.38%~149.67%,说明杉木林内H1,H2和H3处臭氧质量浓度符合中国风景区等空气清洁地区的水平,可以提供相对清洁的空气质量环境,适合进行森林康养、休闲游憩等活动。
-
将各高度臭氧质量浓度的小时均值与春夏两季气象因子进行相关分析,结果如表 1所示。春季H1,H2和H3处温度、风速与臭氧质量浓度呈极显著正相关(P<0.01),相关系数分别为0.839, 0.839, 0.825和0.699, 0.741, 0.762;与相对湿度、气压呈极显著负相关(P<0.01),相关系数分别为-0.895,-0.909,-0.839和-0.650, 0.741,0.762;夏季同样与温度、风速呈极显著正相关(P<0.01),相关系数分别为0.818, 0.741, 0.804和0.824, 0.838, 0.810;与相对数度呈极显著负相关(P<0.01),相关系数分别为-0.881,-0.916,-0.874。
表 1 春秋季节杉木林不同高度臭氧质量浓度与小气候因子的相关性分析
Table 1. Correlation coefficients of ozone concentration and meteorological factors in vertical gradient
季节 垂直梯度 温度 相对湿度 气压 风速 光照强度 紫外辐射 H1 0.839** -0.895** -0.650* 0.699* -0.223 -0.314 春季 H2 0.839** -0.909** -0.776** 0.741** -0.216 -0.293 H3 0.825** -0.839** -0.839** 0.762** -0.349 -0.405 H1 0.818** -0.881** -0.084 0.824** -0.307 -0.314 夏季 H2 0.741** -0.916** -0.105 0.838** -0.118 -0.153 H3 0.804** -0.874** -0.178 0.810** -0.153 -0.167 说明:*表示在置信度(双侧)为0.05时显著相关;**表示在置信度(双侧)为0.01时极显著相关 由表 1结果可知:春夏两季杉木林环境内,各高度臭氧质量浓度与气象因子相关性存在一定差异,其中温度、相对湿度、风速与臭氧质量浓度在两季相关性一致;但气压在春季与臭氧有显著相关性,然而夏季相关性不显著;光照强度与紫外辐射在春夏两季均与臭氧质量浓度无显著相关。一定程度下温度升高使臭氧质量浓度升高,其原因可能是,臭氧的生成和运输达到一定温度阈值后,促进杉木林内植物挥发物释放,同时加强光化学反应速率[18],形成空气湍流引起气体交换,进一步输入氮氧化物(NOx)等人为源。森林环境内可在一定程度起到增湿的作用。林内水汽增加,提升臭氧的光化学消耗,在对流层中水汽与臭氧的反应起到汇的作用,反应生成的自由基也是大气光化学过程的重要触发机制。风速对于臭氧质量浓度的积累通常与其传输特质有关,林内风速增大,垂直动量输送加强,有利于近地面层臭氧向林内输送。另外,风速越大湍流作用越强,越有利于光化学反应速率的提升。
Ozone concentrations of three different vertical gradients for a Cunninghamia lanceolata forest in spring and summer at Yandang Mountain National Forest Park, Wenzhou
-
摘要: 森林中臭氧浓度不仅影响林木生长,也影响游憩环境质量,是森林康养环境研究的热点之一。根据2017年春夏两季对温州雁荡山国家森林公园内杉木Cunninghamia lanceolata林不同垂直高度臭氧浓度及气象因子昼夜24 h同步监测数据,分析了不同高度臭氧浓度的变化规律及其影响因素。结果表明:除春季H3(林冠上层)臭氧质量浓度日最大8 h均值达到中国二类环境功能区质量要求外(≤200 μg·m-3),两季节中其余各高度臭氧质量浓度日最大8 h均值及小时均值均达到中国一类环境功能区质量要求(≤160 μg·m-3);春夏两季各高度臭氧质量浓度从小到大依次为H1(距地面1.5 m),H2(林冠中部)和H3,且春季H1,H2和H3臭氧质量浓度日均值差值高于夏季;两季各高度臭氧质量浓度均为日间高、夜间低,且高值出现于11:00-15:00,低值出现于5:00;春夏两季各高度臭氧质量浓度小时均值与温度、风速呈正相关,与相对湿度呈负相关;春季各高度臭氧质量浓度与气压呈负相关。总体来讲,在雁荡山杉木林环境中,以臭氧质量浓度变化规律为游憩及游憩设施布设标准,在时间的选择上,夏季比春季更适合出游,且夜间优于白天;在空间的选择上,建议选择林下及树冠中部布置游憩设施,如林下栈道及空中栈道或森林木屋等设施。Abstract: Research on ozone concentration in forests has become a hot area of forest recreation because of its influence on forest growth and environmental quality. The variation of ozone mass concentration at different vertical heights in forest environment has a guiding role in forest recreation activities. Ozone concentration and meteorological factors in three different vertical gradients(The following are expressed by H1, H2 and H3 respectively. H1 stands for 1.5 m from ground, H2 indicates the central part of canopy, H3 means the boundary between canopy and atmosphere.) in Yandang Mountain were monitored for 24 h in the spring and summer of 2017. Their changing features and influencing factors were also observed at the same time. In this experiment, ozone sampler was used to sample three kinds of ozone mass concentration, and the data were processed by variance analysis and multiple comparison analysis. Results indicated that the mean value of 8 h maximum ozone concentration in three different vertical gradients all achieved the primary standard for ambient air quality standards(100 μg·m-3) except for the top of H3 (103.03 μg·m-3) during the spring. Ozone concentration changes for the different vertical gradients was H1 < H2 < H3 in both spring and summer with differences in the daily mean ozone concentration between H1 and H2 and H3 being higher in spring than in summer, there was a significant difference between H2 and H3 (P < 0.05). During the observation period for the two seasons, the daily ozone concentration in the different vertical gradients (H1, H2, and H3) all exhibited a single peak curve, with the highest concentration occurring in 11:00-15:00, whereas the lowest occurring in 5:00. The mean value of the hourly ozone concentration for H1, H2, and H3 during the two seasons was positively related with temperature and wind speed and negatively with humidity as well as pressure. In conclusion, Taking ozone concentration as recreation standard, summer nights was more suitable for people to travel. It was advisable to choose the understory and the middle of the canopy to arrange recreation facilities, such as a plank road in the understory or overhead and a wooden house in a C. lanceolata forest.
-
表 1 春秋季节杉木林不同高度臭氧质量浓度与小气候因子的相关性分析
Table 1. Correlation coefficients of ozone concentration and meteorological factors in vertical gradient
季节 垂直梯度 温度 相对湿度 气压 风速 光照强度 紫外辐射 H1 0.839** -0.895** -0.650* 0.699* -0.223 -0.314 春季 H2 0.839** -0.909** -0.776** 0.741** -0.216 -0.293 H3 0.825** -0.839** -0.839** 0.762** -0.349 -0.405 H1 0.818** -0.881** -0.084 0.824** -0.307 -0.314 夏季 H2 0.741** -0.916** -0.105 0.838** -0.118 -0.153 H3 0.804** -0.874** -0.178 0.810** -0.153 -0.167 说明:*表示在置信度(双侧)为0.05时显著相关;**表示在置信度(双侧)为0.01时极显著相关 -
[1] 梁碧玲, 张丽, 赖鑫, 等.深圳市臭氧污染特征及其与气象条件的关系[J].气象与环境学报, 2017, 33(1):66-71. LIANG Biling, ZHANG Li, LAI Xin, et al. Analysis of the characteristics of ozone pollution and its relationship with meteorological conditions in Shenzhen[J]. J Meteorol Environ, 2017, 33(1):66-71. [2] ZHANG Yunhi, HUANG Wei, LONDON S J, et al. Ozone and daily mortality in Shanghai, China[J]. Environ Health Perspect, 2006, 114(8):1227-1232. [3] D'AMATO G. Effects of climatic changes and urban air pollution on the rising trends of respiratory allergy and asthma[J]. Multidisciplin Respir Med, 2011, 6(1):28-37. [4] MARTÍNEZ-LAZCANO J C, GONZÁLEZ-GUEVARA E, DEL C R M, et al. The effects of ozone exposure and associated injury mechanisms on the central nervous system[J]. Rev Neurosci, 2013, 24(3):337-352. [5] ZWICK H, POPP W, WAGNER C, et al. Effects of ozone on the respiratory health, allergic sensitization, and cellular immune system in children[J]. Am Rev Respir Dis, 1991, 144(5):1075-1079. [6] PARMESAN C. Ecological and evolutionary responses to recent climate change[J]. Ann Rev Ecol Evol Syst, 2006, 37(1):637-669. [7] ZOU Y, DENG X J, ZHU D, et al. Characteristics of 1 year of observational data of VOCs, NOx and O3 at a suburban site in Guangzhou, China[J]. Atmos Chem Phys, 2015, 15(12):6625-6636. [8] 王红丽.上海市光化学污染期间挥发性有机物的组成特征及其对臭氧生成的影响研究[J].环境科学学报, 2015, 35(6):1603-1611. WANG Hongli. Characterization of volatile organic compounds (VOCs) and the impact on ozone formation during the photochemical smog episode in Shanghai, China[J]. Acta Sci Circumstant, 2015, 35(6):1603-1611. [9] 杨春燕, 陈圣波, 汪自军.大气辐射在臭氧反演中的应用[J].安徽农业科学, 2010, 38(6):3305-3308. YANG Chunyan, CHEN Shengbo, WANG Zijun. Application of atmospheric radiation in ozone retrieval[J]. J Anhui Agric Sci, 2010, 38(6):3305-3308. [10] 姚青, 孙玫玲, 刘爱霞.天津臭氧浓度与气象因素的相关性及其预测方法[J].生态环境学报, 2009, 18(6):2206-2210. YAO Qing, SUN Meiling, LIU Aixia. Analysis and prediction of surface ozone concentration and related meteorological factors in summer in Tianjin[J]. Ecol Environ Sci, 2009, 18(6):2206-2210. [11] 姜峰, 王福伟.夏季城市臭氧浓度变化规律分析[J].环境与可持续发展, 2016(1):62-64. JIANG Feng, WANG Fuwei. Analysis of the changes of urban ozone concentration in summer[J]. Environ Sustain Dev, 2016(1):62-64. [12] 杨洋, 马三梅, 王永飞.植物气孔的类型、分布特点和发育[J].生命科学研究, 2011, 15(6):550-555. YANG Yang, MA Sanmei, WANG Yongfei. Classification, distribution, development of plant stomata[J]. Life Sci Res, 2011, 15(6):550-555. [13] 列淦文, 叶龙华, 薛立.臭氧胁迫对植物主要生理功能的影响[J].生态学报, 2014, 34(2):294-306. LIE Ganwen, YE Longhua, XUE Li. Effects of ozone stress on major plant physiological functions[J]. Acta Ecol Sin, 2014, 34(2):294-306. [14] 段玉森, 张懿华, 王东方, 等.我国部分城市臭氧污染时空分布特征分析[J].环境监测管理与技术, 2011, 23(12):34-39. DUAN Yusen, ZHANG Yihua, WANG Dongfang, et al. Spatialtemporal patterns analysis of ozone pollution in several cities of China[J]. Administrat Tech Environ Monit, 2011, 23(12):34-39. [15] 徐敬, 张小玲, 赵秀娟, 等.夏季局地环流对北京下风向地区O3输送的影响[J].中国环境科学, 2009, 29(11):1140-1146. XU Jing, ZHANG Xiaoling, ZHAO Xiujuan, et al. Influence of summer local circulation on the transportation of ozone from urban to the downwind area in Beijing[J]. China Environ Sci, 2009, 29(11):1140-1146. [16] 王荣堂, 王有宁, 董秀荣.地膜覆盖棉花、玉米、大豆生育盛期的降温效应[J].生态学报, 2003, 23(8):1667-1672. WANG Rongtang, WANG Youning, DONG Xiurong. Effects of plasic film covering on dropping ground temperature at the full-growing stages of cotton, maize and soybean[J]. Acta Ecol Sin, 2003, 23(8):1667-1672. [17] 苏彬彬.华东森林及高山背景区域臭氧变化特征及影响因素[J].环境科学, 2013, 34(7):2519-2525. SU Binbin. Characteristics and impact factors of O3 concentrations in mountain background region of East China[J]. Environ Sci, 2013, 34(7):2519-2525. [18] 段晓瞳, 曹念文, 王潇, 等. 2015年中国近地面臭氧浓度特征分析[J].环境科学, 2017, 38(12):4976-4982. DUAN Xiaotong, CAO Nianwen, WANG Xiao, et al. Characteristics analysis of the surface ozone concentration of China in 2015[J]. Environ Sci, 2017, 38(12):4976-4982. [19] 谈建国, 陆国良, 耿福海, 等.上海夏季近地面臭氧浓度及其相关气象因子的分析和预报[J].热带气象学报, 2007, 23(5):515-520. TAN Jianguo, LU Guoliang, GENG Fuhai, et al. Analysis and prediction of surface O3 voncentration and telated meteorological factors in summertime in urban area of Shanghai[J]. J Trop Meteorol, 2007, 23(5):515-520. [20] 常杰, 任远, 史琰, 等.亚热带城乡复合系统BVOC排放清单:以台州地区为例[J].生态学报, 2012, 32(2):641-649. CHANG Jie, REN Yuan, SHI Yan, et al. An inventory of BVOC meissions for a subtropical urban-rural complex:Greater Taizhou Area[J]. Environ Sci, 2012, 32(2):641-649. [21] 蔡彦枫, 王体健, 谢旻, 等.南京地区大气颗粒物影响近地面臭氧的个例研究[J].气候与环境研究, 2013, 18(2):251-260. CAI Yanfeng, WANG Tijian, XIE Min, et al. Impacts of atmospheric particles on surface in Nanjing[J]. Clim Environ Res, 2013, 18(2):251-260. [22] 徐晓斌, 葛宝珠, 林伟立.臭氧生成效率(OPE)相关研究进展[J].地球科学进展, 2009, 24(8):845-853. XU Xiaobin, GE Baozhu, LIN Weili. Progresses in the research of ozone production efficiency (OPE)[J]. Adv Earth Sci, 2009, 24(8):845-853. [23] 王自发, 李丽娜, 吴其重, 等.区域输送对北京夏季臭氧浓度影响的数值模拟研究[J].自然杂志, 2008, 30(4):194-198. WANG Zifa, LI Lina, WU Qizhong, et al. Simulation of the impacts of regional transport on summer ozone levels over Beijing[J]. Chin J Nat, 2008, 30(4):194-198. [24] STREETS D J, FU J H S, JANG C J, et al. Air quality during the 2008 Beijing Olympic Games[J]. Atmos Environ, 2007, 41(3):480-492. [25] ORDÓÑEZ C, BRUNNER D, STAEHELIN J, et al. Strong influence of lowermost stratospheric ozone on lower tropospheric background ozone changes over Europe[J]. Geophys Res Lett, 2007, 34(7):L07805+. doi:10.1029/2006GL029113,2007. [26] VINGARZAN R. A review of surface ozone background levels and trends[J]. Atmos Environ, 2004, 38(21):3431-3442. [27] 侯雪伟, 朱彬, 王东东.东亚季风转换对西北太平洋近地面O3春季高值的影响[J].气候与环境研究, 2012, 17(3):303-314. HOU Xuewei, ZHU Bin, WANG Dongdong. The impact of East Asia Monsoon's conversion on the surface ozone spring maximum in the northwestern Pacific region[J]. Clim Environ Res, 2012, 17(3):303-314. [28] LAMAUD E, CARRARA A, BRUNET Y, et al. Ozone fluxes above and within a pine forest canopy in dry and wet conditions[J]. Atmos Environ, 2002, 36(1):77-88. [29] 刘新春, 钟玉婷, 何清, 等.塔克拉玛干沙漠腹地近地面臭氧浓度变化特征及影响因素分析[J].中国沙漠, 2013, 33(2):626-633. LIU Xinchun, ZHONG Yuting, HE Qing, et al. The variation characteristics and influencing factors of surface ozone concentration in the Taklimakan Desert Hinterland[J]. J Desert Res, 2013, 33(2):626-633. [30] 陈魁, 郭胜华, 董海燕, 等.天津市臭氧浓度时空分布与变化特征研究[J].环境与可持续发展, 2010, 35(1):17-20. CHEN Kui, GUO Shenghua, DONG Haiyan, et al. Study on the space-time distribution and change characteristic of ozone concentration in Tianjin[J]. Environ Sustain Dev, 2010, 35(1):17-20. [31] 郑冬, 李丹, 纪德钰, 等.大连市区近地面臭氧污染规律研究及与PM2.5等污染物的相关性分析[J].环境与可持续发展, 2014, 39(6):177-180. ZHENG Dong, LI Dan, JI Deyu, et al. Study on ozone in dalian urban and correlation between ozone and PM2.5, other pollutants[J]. Environ Sustain Dev, 2014, 39(6):177-180. [32] 白建辉, 徐永福, 陈辉, 等.鼎湖山森林地区臭氧及其前体物的变化特征和分析[J].气候与环境研究, 2003, 8(3):370-380. BAI Jianhui, XU Yongfu, CHEN Hui, et al. The variation characteristics and analysis of ozone and its precursors in the Dinghushan Mountain forest area[J]. Clim Environ Res, 2003, 8(3):370-380. [33] 刘建, 吴兑, 范绍佳, 等.前体物与气象因子对珠江三角洲臭氧污染的影响[J].中国环境科学, 2017, 37(3):813-820. LIU Jian, WU Dui, FAN Shaojia, et al. Impacts of precursors and meteorological factors on ozone pollution in Pearl River Delta[J]. China Environ Sci, 2017, 37(3):813-820. [34] 陈漾, 张金谱, 黄祖照.广州市近地面臭氧时空变化及其与气象因子的关系[J].中国环境监测, 2017, 33(4):99-109. CHEN Yang, ZHANG Jinpu, HUANG Zuzhao. Spatial-temporal variation of surface ozone in Guangzhou and its relations with meteorological factors[J]. Environ Monit China, 2017, 33(4):99-109. [35] 齐冰, 牛彧文, 杜荣光, 等.杭州市近地面大气臭氧浓度变化特征分析[J].中国环境科学, 2017, 37(2):443-451. QI Bing, NIU Yuwen, DU Rongguang, et al. Characteristics of surface ozone concentration in urban site of Hangzhou[J]. China Environ Sci, 2017, 37(2):443-451. [36] 刘姣姣, 蒋昌潭, 宋丹, 等.重庆夏季近地面臭氧变化规律及影响因素分析[J].重庆大学学报(自然科学版), 2014, 37(8):91-98. LIU Jiaojiao, JIANG Changtan, SONG Dan, et al. Analysis of distribution characteristics of surface ozone and its influencing factors in summer in Chongqing[J]. J Chongqing Univ Nat Sci Ed, 2014, 37(8):91-98. [37] 陈鹏飞, 张蔷, 权建农, 等.北京地区臭氧时空分布特征的飞机探测研究[J].环境科学, 2012, 33(12):4141-4150. CHEN Pengfei, ZHANG Qiang, QUAN Jiannong, et al. Temporal and spatial distribution of ozone concentration by aircraft sounding over Beijing[J]. Chin J Environ Sci, 2012, 33(12):4141-4150. -
链接本文:
https://zlxb.zafu.edu.cn/article/doi/10.11833/j.issn.2095-0756.2019.02.011