酸雨胁迫对秃瓣杜英幼苗叶片叶绿素荧光特性和生长的影响

采用盆栽试验和模拟酸雨喷淋的试验方法,研究了重度酸雨(pH 2.5)、中度酸雨(pH 4.0)和对照(pH 5.6)处理下,不同季节秃瓣杜英幼苗叶片的叶绿素荧光特性及其生长差异.结果表明：不同季节相同处理下,秃瓣杜英幼苗叶片的相对叶绿素含量(SPAD)、PSⅡ的最大光化学效率(F_v/F_m)、PSⅡ实际光化学量子产量(Φ_PSⅡ)、株高和地径均为10月＞7月＞4月＞1月;同一季节不同处理中,SPAD、F_v/F_m、Φ_PSⅡ、株高和地径为重度酸雨＞中度酸雨＞对照;不同pH酸雨梯度处理和季节的交互作用对秃瓣杜英的SPAD、F_v/F_m、株高和地径的影响显著,而对Φ_PSⅡ、光化学淬灭系数和非光化学淬灭系数的影响不显著.     

广州市酸雨成分及其相关分析

分析了2003年11月-2004年10月广州市龙洞79次降雨的化学组分及其各组分之间的相关关系。得出:(1)观测期间总降雨量1359.8,单次降雨的pH值在3.22-7.29之间,平均4.83;以pH<5.6为酸雨的临界值,则酸雨频率占降雨次数的77.2%或占降雨量的81.5%;(2)广州降水的化学组成以SO₄^2-、Cl^-和NO₃^-为主要阴离子,阳离子中以Ca²⁺、NH₄⁺、Na⁺所占比例较大;(3)广州地区酸雨属硫酸型,降雨中的SO₄^2-、NO₃^-、PO₄^3-、Cl^-、NH₄⁺、K⁺、Na⁺、Ca²⁺、Mg²⁺离子浓度分别为0.150,0.045,0.002,0.163,0.058,0.006,0.013,0.083和0.007mol·L^-1,单次降雨的SO₄^2-/NO₃^-比值在0.42-17.6之间,年平均为3.33,该值比西南地区相应值低许多,而且与同一地点5年前测定的结果相比较,SO₄^2-/NO₃^-比值有变小的趋势,说明广州地区NO_x排放量高逐渐增加;(4)广州地区酸雨有着明显的季节变化规律,春、夏、秋季酸雨比较严重,冬季酸雨较少出现,这与西南地区的重庆(冬季酸雨较春季严重)酸雨季节规律相反;(5)通过SPSS统计分析得出,雨量与各化学组分含量成负相关,说明雨量对大气污染物质的稀释作用;酸雨各化学成分之间存在着一定的相关性,如SO₄^2-与Ca²⁺,NO₃^-与NH₄⁺,K⁺与Na⁺、Mg²⁺离子,Na⁺与Mg²⁺等都存在显著的正相关,利用这种相关可以建立某些酸雨成分的预测模型。     

酸雨对龙眼果树影响研究

通过大田和室内模拟试验,研究酸雨对龙眼果树的影响。结果表明酸雨使龙眼树叶、梢、芽的营养元素K、Mg、P、Fe、Zn、Mn渗出;叶绿素降低;酸雨中的H⁺、Cl^-被吸收;细胞受损害,随着酸雨PH值下降,伤害程度加大,PH<3伤害是不可逆转的;Ca²⁺似有在逆境中迅速运输以起保护作用的倾向;每升含KH₂PO₄ 1.0mg、Ca(NO₃)₂ 3.3mg,FeSO₄42μg,H₃BO₃29μg的混合液在酸雨之前或后喷淋果树,能降低伤害,浓度上限可至50倍。花、蕾、幼果受酸雨的伤害,程度是花>蕾>幼果,喷淋每升含Ca(NO₃)₂3.3mg,KNO₃2.7mg,FeSO₄42μg的混合溶液可起保幼果作用。土壤肥沃、田间管理好、营养充分,能有效拮抗酸雨的侵害。     

树木气孔浸润级与SO2伤害及ABA的防护作用

以常见绿化树种为材料,通过实地测定和熏烟实验,探讨了气孔浸润级与树木SO₂伤害的关系及ABA的防护效应.结果表明,在特定环境下,相同树种的气孔浸润级较为稳定,不同树种的气孔浸润级差异较大;浸润级与叶绿素结合度呈负相关变化,但不明显;与K⁺渗出量呈正相关(r=0.92,α＜0.01),并按95%的置信度绘制了伤害预测图.不同SO₂浓度条件下,对同一树种的气孔浸润级的影响甚小,不超过一个等级,K⁺渗出量则依大气SO₂浓度和树木吸S量的增加而增多.气孔浸润级依ABA溶液处理浓度增大而降低,K⁺渗出量也相应减少,经2.5mol·L^-1×4h剂量的SO₂熏烟,预涂30mol·L^-1ABA者,降低了1.5～3个浸润级,K⁺渗出量减少36.5%～54.8%,其测定值与自然对照值相近,防护作用显著.     

Light and CO2 responses of photosynthesis and chlorophyll fluorescence characteristics in bean plants after simulated acid rain

The effects of simulated acid rain on some chlorophyll fluorescence characteristics and photosynthetic gas exchange at different light intensities and CO₂ concentrations of bean plants were investigated. Measurements were carried out 3, 5 and 24 h after spraying. The results showed that a single acid rain (pH 1.8) treatment of bean plants reduced gas exchange, the maximal carboxylating efficiency and photochemical quenching. This treatment led also to increased CO₂ compensation point and non-photochemical quenching and changed the shape of CO₂ and light curves of photosynthesis. Both stomatal and non-stomatal factors contributed to the decreased photosynthetic rate, but their proportion changed with time of recovery of the photosynthetic ampparatus. Three hours after the treatment, the stomatal factors predominated in photosynthesis reduction, while during the next experimental period (5–24 h), mainly non-stomatal factors determined the decreased photosynthetic rate. It is suggested that the effects observed in consequence of acid rain treatment could be due to an increased intracellular accumulation of H⁺ and harmful ions contained in the cocktail. This probably led to impaired membrane permeability, enhancement of stroma acidity, uncoupled electron transport and insufficient accumulation of ATP and NADPH, which affected carbon metabolism.     

Lack of physiological response of two corn hybrids to simulated acid rain

Simulated acid rain has been reported to cause physiological changes in various plant species. Studies were conducted in 1983, 1984 and 1985 to determine the effect of acid rain on some physiological parameters in two corn (Zea mays L.) hybrids. Simulated rain of pH 3.0, 4.2, and 5.6 was applied throughout the growing season onto plots protected from ambient rain and grown on a Flanagan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll). Individual plants were evaluated for change in leaf CO₂ fixation, water potentials, chlorophyll content, and in vitro pollen germination. Rain pH did not affect any of these parameters. Within the limits of experimental error, it must be concluded that simulated acid rain of pH 3.0 did not affect the physiological parameters measured in this study.     

模拟酸雨对番木瓜不同成熟度叶片膜脂过氧化作用的影响

用不同pH值(4．5、3．5、3．0、2．5)的模拟酸雨处理,研究其对番木瓜不同成熟度叶片细胞膜透性和膜 脂脂防酸组分变化的影响。结果表明,酸雨处理导致番木瓜叶片细胞膜透性、MDA含量、脂氧合酶(LOX)活 性和K+、Ca2+、Mg2+渗出量显著上升,膜脂肪酸组分中饱和脂肪酸含量增加,不饱和脂肪酸含量及不饱和指 数(IUFA)下降,嫩叶比成熟叶对酸雨的反应更敏感。运用生理指标差异达0．05显著水平评价酸雨对番木瓜 的影响阈值,嫩叶在pH3．5,成熟叶在pH3．0。     

Net CO2 exchange of Pinus taeda shoots exposed to variable ozone levels and rain chemistries in field and laboratory settings

Net CO₂ exchange rates (CERs) were measured in seedlings of two loblotly pine ( Pinus taeda L.) families following 6- or 13-week exposures to ozone (charcoalfiltered or ambient air + O₃) and acid rain treatments (pH 3.3, 4.5 and 5.2). Ozone exposures (14 or 170 nl l⁻¹) were made in open-top chambers, and in continously stirred tank reactors (14, 160 or 320 nl l⁻¹) located in the field and laboratory, respectively. The CERs of whole shoots were measured in an open infrared gas analysis system at 6 levels of photosynthetic photon flux density (0, 33, 60, 410, 800 and 1660 μmol m⁻² s⁻¹). Treatment effects were not consistent between field- and laboratory-exposed seedlings. Ozone-treated field seedlings exhibited statistically significant reductions in light-saturated CER of 12.5 and 25% when measured at 6 and 13 weeks, respectively. Laboratory seedlings exhibited mixed responses to O₃, with one family showing reduced CER only after 6 weeks of O₃ exposure and the other only after 13 weeks (O₃ >160 nl l⁻¹ for both). After 13 weeks of exposure, pH 3.3, and 4.5 rain treatments enhanced light-saturated CER by an average of 52% over that observed in seedlings exposed to the pH 5.2 treatment. Enhanced CERs due to acid rain were of the same magnitude (3–5 μmol CO₂g⁻¹ s⁻¹) as ozone-induced CER reductions. No differences in dark respiration were detected between treatments. Although ozone and acid rain treatments altered seedling CER, the differences were not translated into altered final plant dry weights over the 13-week exposure period.     

模拟酸雨对红壤区茶树器官氮磷含量及其化学计量比的影响

以红壤区25年生茶园为对象,开展pH 4.5、pH 3.5、pH 2.5及自来水(对照)4种强度模拟酸雨处理原位试验,于处理第3年收集茶树体不同功能根系和不同年龄枝、叶,测定氮(N)、磷(P)含量,并计算化学计量比和酸雨响应敏感度.结果表明: 土壤pH值、硝态N和有效P随酸雨强度增加而显著降低.吸收根N含量随酸雨强度增加而提高,pH 2.5处理下吸收根N含量与对照相比显著提高32.9%;储藏根P含量随酸雨强度增强而显著降低;同时酸雨处理显著提高吸收根N/P.新叶和老叶N、P含量对不同强度酸雨处理响应不敏感,但酸雨处理增加了老叶N/P,且在pH 3.5处理下达到显著水平.酸雨处理对枝条的影响与其年龄有关,新枝N含量和N/P在低强度酸雨(pH 4.5)处理下显著增加,而老枝N含量和N/P对酸雨处理响应不敏感.吸收根、新叶和新枝N含量对酸雨响应敏感度分别高于储藏根、老叶和老枝,而储藏根和叶片P含量对酸雨响应敏感度高于其他器官.茶树器官N含量对酸雨处理较为敏感,适度酸雨可增加幼嫩器官N含量和N/P,改变茶树体N、P的循环和平衡.     

Effects of pH, NADH, succinate and malate on the oxidation of glycine in spinach leaf mitochondria

The effect of external pH on several reactions catalyzed by glycine decarboxylase in spinach leaf mitochondria was investigated. Glycine-dependent oxygen consumption showed a pH optimum at 7.6, whereas the release of CO₂ and NH3 from glycine in the presence of oxaloacetate both showed pH maxima at 8.1. Glycine-dependent reduction of 2,6-dichlorophenolindophenol. on the other hand showed a pH optimum at 8.4. It is concluded that these three reactions have different rate-limiting steps. The rate of the glycine-bicarbonate exchange reaction catalyzed by glycine decarboxylase showed no optimum in the pH range investigated, pH 7–9, but increased with decreasing pH. This suggests that CO₂ may be the true substrate in this reaction.
The oxidation of glycine inhibited the oxidation of both malate, succinate and external NADH since the addition of malate, succinate or NADH to mitochondria oxidizing glycine in state 3 resulted in a rate of oxygen consumption which was lower than the sum of the rates when the substrates were oxidized individually. The addition of malate, succinate or NADH did not, however, decrease the rate of CO₂ or NH, release from glycine. It is suggested that the preferred oxidation of glycine by-spinach leaf mitochondria may constitute an important regulatory mechanism for the function of leaf mitochondria during photosynthesis.