大气SO_2和NO_2污染及植物的抗性和净化能力研究进展

SO_2和NO_2为我国大气污染主要污染物,城市森林对SO_2和NO_2具有一定的抵抗能力和吸收净化能力,利用城市森林对大气污染进行修复具有良好的应用前景。文章概述了我国SO_2和NO_2气体污染的状况,总结了污染物进入植物体的过程及其损伤机理,并从植物抗性和吸附净化能力两方面总结了城市景观树种与SO_2和NO_2气体污染的关系研究,并基于研究结论提出今后研究可能发展方向,如SO_2、NO_2与悬浮颗粒物等复合污染对城市树种生长的影响、树种抗性和吸附能力综合研究等。     

云南13种乡土绿化树种对SO2、NO2气体反应的研究

采用人工模拟熏气的方法,研究了13种云南乡土绿化树种对城市SO2、NO2有害气体的反应.结果表明云南红豆杉、长梗润楠、翠柏、滇润楠、麻栗坡含笑、南亚含笑、山玉兰对SO2气体的抗性弱,而云南含笑、脉叶虎皮楠、川滇三角枫对SO2气体的抗性最强,灯台树、川滇三角枫净化SO2的能力较强,其净化量分别为300mg·kg-1、700 mg·kg-1.NO2浓度为1.0 mg·m-3时,长梗润楠、云南含笑、云南拟单性木兰、云南红豆杉、麻栗坡含笑、灯台树叶片的N净化量依次为2 000 mg·kg-1、1 100 mg·kg-1、1 700 mg·kg-1、2 300 mg·kg-1、1 200 mg·kg-1、13 100 mg·kg-1.经综合比较川滇三角枫对SO2气体具有较好的抗性和净化能力,而对NO2气体具有较好的抗性;云南含笑、云南拟单性木兰、脉叶虎皮楠等树种对SO2、NO2气体具有较好的抗性和净化能力.     

城市森林净化大气颗粒物污染作用研究进展

粉尘颗粒物污染,尤其是PM2.5污染,是我国大气污染的主要问题.城市森林和绿地是城市生态系统中具有自净功能的重要组成部分,利用城市森林和绿地治理大气颗粒物污染受到越来越多的关注,并具有良好的应用前景.文章概述我国粉尘颗粒物污染状况,并总结了植物净化大气污染研究概况,从4个角度总结目前城市森林与PM2.5的关系研究,包括森林对颗粒物吸附机制、PM2.5对植物的危害影响、不同尺度下植被移除PM2.5的效果比较以及影响吸附过程的其他因素,提出了今后研究的可能发展方向,包括扩大研究树种的范围、针对研究不同树种特异性吸附偏好及加强各尺度研究的结合等,以更有效地应用城市森林进行大气污染修复.     

棱角山矾抗大气中SO2和HF的能力

棱角山矾受大气污染物SO2和HF污染后,测定了其叶片中超氧化物歧化酶（SOD）活性、细胞膜透性、S及F的含量以及酸碱缓冲能力等生理指标,并结合棱角山矾树体生长情况,综合评价其对大气中SO2和HF的抗性.结果表明：棱角山矾在以SO2和HF为主的混合大气污染物中均表现出较强的抗性,尤其对S污染物具有良好的吸收净化功能,其吸S能力达到11.98 g/kg.     

草本花卉对SO2抗性能力的试验研究

探索研究了草花对大气污染物SO2的抗性强弱。结果表明:不同的草花对大气污染物SO2抗性不同,有的对大气污染物SO2特别敏感,有的却表现出很好的抗性。敏感性强的花卉如矮牵牛、百日草等可以作为SO2污染与否的指示植物;对SO2抗性能力强的草花,可以在绿化美化城市、建立园林式化工企业方面充分发挥作用。     

大气中SO2对植物生理的影响

指出了随着社会经济快速发展和人民生活水平的不断提高,大气中的SO2已成为大气污染的主要污染物。由于植物对SO2的具有净化能力,因此了解大气中SO2对植物的生理影响是十分重要的。通过查阅大量文献,阐述了了大气中SO2对植物在各种生理方面的影响,从而说明了利用绿化植物对SO2的吸收、转移作用可以减轻SO2污染的可行性。     

棱角山矾抗SO2大气污染的机理

野外调查了棱角山矾抗SO2大气污染的生长状况,为探讨其抗性机理,进行了室内外加HSO3-处理试验,测定了SOD酶活性、叶绿素含量、硫含量和细胞液pH值及其缓冲能力.结果表明:棱角山矾对SO2污染物具有较强的抗性和吸收能力,其抗性机理可能与树体受污染后SOD酶活性的升高和细胞液的pH缓冲能力有关.     

山东省高速公路绿化对空气的净化效果研究

采用测定SO2、NO2和CO2气体含量的方法,研究了山东省主要高速公路路侧绿化带,互通立交区、入口匝道区和服务区绿地对空气的净化效果。测定结果表明,路侧绿化带对SO2有较明显的净化作用,互通立交区、入口匝道区和服务区的绿化对SO2和NO2均有较好的吸收净化作用,而高速路绿化对CO2含量的影响则较小。     

工业区大气污染物特性和空间分布动态模型研究

在广州员村工业区主风方向和次主风方向各设置10个采样点，对影响该区大气质量的SO2、NO2和烟尘排放量进行测定，并进行为期四个月的监测．同时，对该区的大气污染状况进行调查，对近6a来的环境资料进行收集．采用灰色系统理论，对各种数据进行关联度矩阵分析，寻找对环境质量影响最大的因子．并研究各污染物的空间分布规律，建立动态模型．为确定理想的抗污净化林带的营造地点提供了理论上的指导     

多孔炭材料吸附CO2研究进展

由CO₂等温室气体排放带来的全球变暖问题是目前最严峻的环境问题之一。因此,利用多孔炭材料作为其高效吸附材料的研究得到了广泛的关注。系统综述了近年来用于CO₂吸附的5种多孔炭材料,即煤/石油焦基活性炭、生物质多孔炭、炭气凝胶、金属有机骨架衍生物和碳纳米材料,以及多孔炭材料主要的4种制备方法(高温炭化与活化法、水热炭化法、溶胶-凝胶法和模板法),并重点讨论其结构与CO₂吸附性能的关系;随后对多孔炭材料的孔结构和表面化学性质吸附CO₂的机理进行总结。最后,提出多孔炭材料吸附CO₂发展过程中尚待解决的问题,并对其未来的发展方向进行了展望。     

O_3浓度升高对桢楠和闽楠幼苗光合作用、抗氧化能力及生物量的影响

[目的]探讨O_3浓度升高对两种亚热带树木幼苗的影响,并分析其敏感性差异及原因。[方法]本试验以1年生桢楠和闽楠幼苗为材料,采用开顶式气室(OTCs),研究未过滤大气、100 nmol·mol-1(E1)、150 nmol·mol-1(E2)O_3处理对光合作用、抗氧化能力和生物量的影响。[结果]研究表明:(1) O_3熏蒸主要通过非气孔限制因素降低了两树种的净光合速率(Pn)。其中对于桢楠,E2对Pn的不利影响大于E1。而对于闽楠,8月份E2的Pn大于E1,而9月份和10月份小于E1。(2) O_3熏蒸提高了两树种的抗氧化能力,表现为总酚含量和总抗氧化能力随着O_3浓度的升高逐渐升高,而E2的还原型抗坏血酸含量低于E1。(3) O_3熏蒸降低了两树种根、茎、叶及总干质量,及降低了闽楠的根茎比。[结论]O_3熏蒸降低了两树种的光合作用,提高了抗氧化能力,最终减少了生物量。根据Pn和生物量,确定闽楠较桢楠对O_3浓度升高更加敏感。两树种间的O_3敏感性差异与气孔导度和抗氧化物质的背景水平及其对O_3浓度升高的响应有关。     

Soil CO2 efflux in an Afromontane forest of Ethiopia as driven by seasonality and tree species

Variability of soil CO₂ efflux strongly depends on soil temperature, soil moisture and plant phenology. Separating the effects of these factors is critical to understand the belowground carbon dynamics of forest ecosystem. In Ethiopia with its unreliable seasonal rainfall, variability of soil CO₂ efflux may be particularly associated with seasonal variation. In this study, soil respiration was measured in nine plots under the canopies of three indigenous trees (Croton macrostachys, Podocarpus falcatus and Prunus africana) growing in an Afromontane forest of south-eastern Ethiopia. Our objectives were to investigate seasonal and diurnal variation in soil CO₂ flux rate as a function of soil temperature and soil moisture, and to investigate the impact of tree species composition on soil respiration. Results showed that soil respiration displayed strong seasonal patterns, being lower during dry periods and higher during wet periods. The dependence of soil respiration on soil moisture under the three tree species explained about 50% of the seasonal variability. The relation followed a Gaussian function, and indicated a decrease in soil respiration at soil volumetric water contents exceeding a threshold of about 30%. Under more moist conditions soil respiration is tentatively limited by low oxygen supply. On a diurnal basis temperature dependency was observed, but not during dry periods when plant and soil microbial activities were restrained by moisture deficiency. Tree species influenced soil respiration, and there was a significant interaction effect of tree species and soil moisture on soil CO₂ efflux variability. During wet (and cloudy) period, when shade tolerant late successional P. falcatus is having a physiological advantage, soil respiration under this tree species exceeded that under the other two species. In contrast, soil CO₂ efflux rates under light demanding pioneer C. macrostachys appeared to be least sensitive to dry (but sunny) conditions. This is probably related to the relatively higher carbon assimilation rates and associated root respiration. We conclude that besides the anticipated changes in precipitation pattern in Ethiopia any anthropogenic disturbance fostering the pioneer species may alter the future ecosystem carbon balance by its impact on soil respiration.     

郑州市数码公园不同植物群落对PM2.5和PM10浓度的影响研究

以郑州市数码公园为例,研究不同植物群落对大气颗粒物污染的影响。2020年4月—2021年3月,监测郑州市数码公园内不同植物群落结构（乔灌草、乔草、乔灌、灌草、草坪）在春夏秋冬四季的PM_2.5和PM₁₀浓度以及温度、湿度和风速等气象因子,分析不同植物群落PM_2.5、PM₁₀浓度的变化规律,并研究其与气象因子的相关性。研究结果表明,不同样地内PM_2.5和PM₁₀浓度日变化基本一致,呈早高晚低趋势。不同样地内PM_2.5和PM₁₀浓度均表现为秋冬季高,春夏季低;PM_2.5和PM₁₀浓度高低依次为草坪和广场样地＞灌草和乔草结构样地＞乔灌草和乔灌结构样地;复合群落结构绿地对颗粒物滞尘能力大于单一群落结构。乔灌草、乔灌结构样地对PM_2.5和PM₁₀的阻滞率较高。PM_2.5和PM₁₀浓度与温度、相对湿度、风速等气象因子间呈不同相关性,PM_2.5浓度与各气象因子的相关性高于PM₁₀浓度。由于数码公园为紧邻城市道路的开放公园,适宜种植郁闭度较高、以常绿树种为主的植物群落类型。     

Na2SO4胁迫对沙枣幼苗生长和光合生理的影响

采用盆栽控制试验,研究了不同浓度(0、60、120和180 mmol·L-1)Na2SO4胁迫对沙枣幼苗生长和光合特性的影响。结果表明:(1)盐胁迫对沙枣幼苗生长具有显著的抑制效应。不同浓度Na2SO4胁迫沙枣的株高、侧枝数、总叶面积、单株叶片数、比叶面积以及各组织(除根)生物量均显著低于对照,且均随盐胁迫浓度的升高呈下降趋势,而根冠比值则由对照的0.153 1显著增加到180 mmol·L-1Na2SO4胁迫幼苗的0.348 7。(2)盐胁迫显著降低了沙枣幼苗的光合能力。随着Na2SO4胁迫的加剧,净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)和蒸腾速率(Tr)均呈下降的趋势,而气孔限制值(Ls)和水分利用效率(WUE)则依次增加,且Pn下降主要受气孔限制;180 mmol·L-1Na2SO4胁迫沙枣幼苗的Pn、Gs、Ci和Tr分别为对照的71.57%、30.85%、67.15%和51.65%,而Ls和WUE则分别为对照的1.91、1.38倍。(3)盐胁迫强度与幼苗株高、总叶面积、单株叶片数、比叶面积、茎生物量、叶生物量、总生物量等生长指标以及Pn、Gs、Ci、Tr等光合参数呈极显著负相关,叶片的光合参数与总叶面积、单株叶片数呈显著或极显著正相关,而叶片的生长指标、光合参数与幼苗的株高生长和生物量累积也呈显著或极显著正相关。     

Tree age and soil phosphorus conditions influence N2-fixation rates and soil N dynamics in natural populations of Acacia senegal

Acacia senegal, an important leguminous tree in arid and semi-arid environments, has shown promise as a multipurpose species, including gum production and soil fertility improvement, linked with N₂-fixation capabilities. Of particular interest are ontogenetic and edaphic effects on A. senegal performance in natural populations. Our research objectives were to investigate the effect of tree age and site phosphorus conditions on (1) tree N₂-fixation and (2) soil N and C dynamics in natural stands of A. senegal var. senegal, Baringo District, in the Rift Valley, Kenya. Sites consisted of A. senegal saplings (9 months) and mature A. senegal trees (7 years) along an edaphic gradient of soil P availability. A single-tree neighborhood approach was employed using a two by two factorial design: site conditions [high and low soil P contents] and tree age class [juvenile and mature]. Soil (N and C pools and fluxes) and plant metrics were quantified. A soil transfer experiment was also employed to confirm age and site effects on soil N mineralization. On the high soil P site, A. senegal had significantly lower foliar (¹⁵N levels than neighboring non-leguminous species (Balanites aegyptiaca), while foliar δ¹⁵N values in A. senegal on the low P site exhibited no significant difference with our reference plant, B. aegyptiaca. Across P sites, B. aegyptiaca had similar foliar δ¹⁵N values. These results indicate that the rate of N₂-fixation of A. senegal trees, as determined with foliar ¹⁵N natural abundance methodology, increased with increasing soil P availability in these natural populations. However, N₂-fixation rates declined with age. Although soil texture and soil CO₂ efflux did not differ between sites or across ages, soils under mature A. senegal at the high P site exhibited significantly greater total N content and total C content in comparison to soils at the low P site and under juvenile plants. Furthermore, under mature A. senegal trees, soil N mineralization rates were significantly greater as compared to under saplings. Soil transplants confirmed that soil microbial activity may be stimulated under mature trees as N mineralization rates were 2-3 fold greater compared to under A. senegal saplings. Our findings suggest that tree age and soil P availability are important factors in the nitrogen budget of natural populations of A. senegal, determining N₂-fixation rates, and potentially influencing soil total N and C pools and soil mineral N. This study provides information regarding the adaptation of A. senegal under differing edaphic conditions thus increasing accuracy of management support for A. senegal populations as productive agroforests.     

O_3胁迫对三种楠木幼苗光合作用的影响及伤害症状

[目的]随着全球O_3浓度升高,O_3胁迫对植物影响的研究已成为研究的热点之一。我国的相关研究较少,主要以农作物为主,且大多局限在北方地区。本研究探讨O_3胁迫下,亚热带三种楠木幼苗光合作用的变化规律及其可见伤害症状,以期为后续研究提供理论依据。[方法]以一年生亚热带乡土树种桢楠、闽楠和刨花楠幼苗为材料,采用开顶式气室(OTCs),研究低浓度O_3、环境大气、100 n L·L-1O_3、150 n L·L-1O_3处理对光合作用的影响及伤害症状。[结果]研究表明:(1)O_3胁迫下,三种楠木幼苗的光合作用受到一定的抑制,气孔导度和净光合速率的相关性降低,对光合有效辐射的利用范围整体减小,出现了明显的光抑制现象。O_3浓度越高,对桢楠和刨花楠光合作用的抑制效果越明显,而100 n L·L-1O_3处理对闽楠光合作用的抑制效果较150 n L·L-1O_3处理明显。环境大气中的O_3浓度均值较低,但由于其较高的O_3浓度峰值,仍对三种楠木幼苗的光合作用产生了一定的抑制。与环境大气相比,低浓度O_3处理通过消除较高的O_3浓度峰值从而缓解了O_3对光合作用的不利影响。(2)O_3胁迫下,桢楠叶片出现褪绿、黄斑和坏死斑的症状,闽楠叶片出现褪绿、黄斑和水渍的症状,刨花楠叶片出现红褐色斑、水渍、坏死斑、卷曲皱缩、失水萎蔫的症状。三种楠木幼苗叶片的伤害症状随O_3浓度的增加而更明显。[结论]三种楠木幼苗叶片的光合作用均受到O_3的抑制,并出现了伤害症状,可作为O_3污染的指示树种。光合作用对O_3敏感性的关系为:刨花楠闽楠桢楠,其中刨花楠对O_3更敏感,伤害症状也较多样,因此指示O_3污染的效果更好。     

Response of seedlings of different tree species to elevated C02 in Changbai Mountain

Eco-physiological responses of seedlings of eight species,Pinus koraiensis, Picea koraiensis, Larix olgensis, Populus ussuriensis, Betula platyphylla, Tilia amurensis, Traxinus mandshurica andAcer mono from broadleaved/Korean pine forest, to elevated CO₂ were studied by using open-top chambers under natural sunlight in Changbai Mountain, China in two growing seasons (1998–1999). Two concentrations of CO₂ were designed: elevated CO₂ (700 μmol·mol⁻¹) and ambient CO₂ (400 μmol·mol⁻¹). The study results showed that the height growth of the tree seedlings grown at elevated CO₂ increased by about 10%–40% compared to those grown at ambient CO₂. And the water using efficiency of seedlings also followed the same tendency. However, the responses of seedlings in transpiration and chlorophyll content to elevated CO₂ varied with tree species. The broad-leaf tree species were more sensitive to the elevated CO₂ than conifer tree species. All seedlings showed a photosynthetic acclimation to long-term elevated CO₂. Foundation item: The project was supported by National Key Basic Development of China (G1999043400) and the grant KZCX 406-4, KZCX1 SW-01 of the Chinese Academy of Sciences Biography: WANG Miao (1964-), maie, associate professor in Institute of applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. China. Responsible editor: Song Funan     

Determining photosynthetic responses of forest species to elevated [CO2]: Alternatives to FACE

Free air CO₂ enrichment (FACE) experiments are considered the most reliable approach for quantifying our expectations of forest ecosystem responses to changing atmospheric CO₂ concentrations [CO₂]. Because very few Australian tree species have been studied in this way, or are likely to be studied in the near future because of the high installation and maintenance costs of FACE, there are no clear answers to questions such as: (1) which species will be the winners in Australia's natural forests and what are the implications for biodiversity and carbon (C) sequestration; and (2) which will be the most appropriate species or genotypes to ensure the sustainability of Australia's plantation forests.     

Mixed-species plantations of Acacia mangium and Eucalyptus grandis in Brazil: 2: Nitrogen accumulation in the stands and biological N2 fixation

The sustainability of plantation forests is closely dependent on soil nitrogen availability in short-rotation forests established on low-fertility soils. Planting an understorey of nitrogen-fixing trees might be an attractive option for maintaining the N fertility of soils. The development of mono-specific stands of Acacia mangium (100A:0E) and Eucalyptus grandis (0A:100E) was compared with mixed-species plantations, where A. mangium was planted in a mixture at a density of 50% of that of E. grandis (50A:100E). N₂ fixation by A. mangium was quantified in 100A:0E and 50A:100E at age 18 and 30 months by the ¹⁵N natural abundance method and in 50A:100E at age 30 months by the ¹⁵N dilution method. The consistency of results obtained by isotopic methods was checked against observations of nodulation, Specific Acetylene Reduction Activity (SARA), as well as the dynamics of N accumulation within both species. The different tree components (leaves, branches, stems, stumps, coarse roots, medium-sized roots and fine roots) were sampled on 5–10 trees per species for each age. Litter fall was assessed up to 30 months after planting and used to estimate fine root mortality. Higher N concentrations in A. mangium tree components than in E. grandis might be a result of N₂ fixation. However, no evidence of N transfer from A. mangium to E. grandis was found. SARA values were not significantly different in 100A:0E and 50A:100E but the biomass of nodules was 20–30 times higher in 100A:0E than in 50A:100E. At age 18 months, higher δ¹⁵N values found in A. mangium tree components than in E. grandis components prevented reliable estimations of the percentage of N derived from atmospheric fixation (%Ndfa). At age 30 months, %Ndfa estimated by natural abundance and by ¹⁵N dilution amounted to 10–20 and 60%, respectively. The amount of N derived from N₂ fixation in the standing biomass was estimated at 62 kg N ha⁻¹ in 100A:0E and 3 kg N ha⁻¹ in 50A:100E by the ¹⁵N natural abundance method, and 16 kg N ha⁻¹ in 50A:100E by the ¹⁵N dilution method. The total amount of atmospheric N₂ fixed since planting (including fine root mortality and litter fall) was estimated at 66 kg N ha⁻¹ in 100A:0E and 7 kg N ha⁻¹ in 50A:100E by the ¹⁵N natural abundance method, and 31 kg N ha⁻¹ in 50A:100E by the ¹⁵N dilution method. The most reliable estimation of N₂ fixation was likely to be achieved using the ¹⁵N dilution method and sampling the whole plant.