海拔梯度对巴郎山奇花柳叶片δ13C的影响

2010年在四川卧龙自然保护区选择海拔为2350、2700、3150和3530 m的4个分布地点,研究了巴郎山海拔梯度对奇花柳叶片13C、光合、CO2扩散导度、氮含量、光合氮利用效率( PNUE)和比叶面积(SLA)的影响.结果表明:随着海拔的升高,目标树种叶片氮含量(尤其是单位面积氮含量)及PNUE增加,叶片δ13C值也随之显著增加,且海拔每升高1000 m,δ13C增加1.4‰;CO2扩散导度(气孔导度和叶肉细胞导度)的增加,在一定程度上阻碍了叶片δ13C值随海拔升高,但不足以改变δ13C值随海拔升高的趋势;羧化能力是羧化位点与外界CO2分压比( Pc/Pa),甚至δ13C的限制因子.在海拔2350～2700m,奇花柳光合系统内部氮素分配主要受温度的影响,而2700～3530 m的光照作用可能更大.奇花柳的SLA随海拔无显著变化.     

夏季南京市中心-郊区-城市森林梯度上的近地层大气特征

运用定点观测法和车载传感器的流动观测法,研究了夏季沿南京市市中心-郊区-城市森林梯度的近地层大气温度(T_(N-S))、CO_2浓度(p_(N-S)(CO_2))、湿度和污染气体浓度的变化规律.结果表明,沿市中心-郊区-城市森林梯度,T_(N-S)、p_(N-S)(CO_2)、相对湿度(RH_(N-S))和污染物浓度(p_(N-S)(SO_2)和p_(N-S)(NO_2))均表现为规律性的变化,与观测点距市中心的距离间的关系可用logistic方程进行较好的拟合(R~2在0.71～0.90之间).与城市森林(S9)相比,市中心(S1)的T_(N-S)和p_(N-S)(CO_2)在一天中的任何时段均有不同程度的升高,其中,T_(N-S)升高幅度在5:00～6:00时段最小,而在17:00～18:00时段最大,分别为1.3℃和4.7℃,白天和夜间平均分别升高了3.7℃和2.1℃;而p_(N-S)(CO_2)升高幅度在1:00～2:00时段最小,在13:00～14:00时段最大,分别为7.0μmol/mol和66μmol/mol,白天和夜间平均分别升高了55μmol/mol和20μmol/mol.S1和S9点间,绝对湿度(AH_(N-S))的全天平均值无显著差异;而RH_(N-S)除了5:00～6:00时段两点均接近饱和外,一天中S9点均高于S1点,两点最大差值出现在13:00～14:00时段,S1和S9分别为37.4%和52.9%,全天平均升高了7.0%.与S9点相比,S1点的p_(N-S)(SO_2)和p_(N-S)(NO_2)在上午10:00～11:40间分别升高了0.88倍和2.1倍.表明,当前城市的一些环境因子如T_(N-S)和p_(N-S)(CO_2)相当于全球数十年或更久以后的水平.     

黔西北次生林优势树种叶片-凋落物-土壤连续体有机质碳稳定同位素特征

稳定性碳同位素自然丰度(δ13C)能够揭示生态系统长时间尺度的有机碳动态变化,阐明生态系统功能的变化特征。以黔西北次生林14个优势树种为研究对象,测定叶片、凋落物以及根区土壤有机碳含量和δ13C值,分析不同层次碳含量和δ13C丰度之间的相关性。结果表明:14个优势树种叶片碳含量为404.67—487.14 g/kg,总体为针叶树种较高、常绿灌木较低;δ13C值为-31.2‰—-27.1‰,随生活型的变化规律不明显。凋落物碳含量为414.62—561.31 g/kg,与叶片碳含量的变化规律较为一致;δ13C值为-31.5‰—-27.3‰,随树种生活型的变化特征也不明显。根区土壤碳含量为10.02—91.59 g/kg,δ13C值为-26.8‰—-22.5‰,碳含量以光皮桦、银白杨等落叶乔木较高。叶片、凋落物和根区土壤3个层次的碳含量与δ13C丰度之间均呈不显著相关,不同层次的δ13C丰度之间和碳含量之间均为正相关。研究结果有助于反映森林生态系统碳循环过程的关键信息,为森林植被恢复提供理论依据。     

北京城市绿化树种叶片碳同位素组成的季节变化及与土壤温湿度和气象因子的关系

城市绿化树种是城市生态系统的重要组成部分,为了探讨城市绿化树种水分利用效率的季节变化及其影响因素,本文对北京24个城市绿化树种(包括6个常绿针叶和18个落叶阔叶树种)叶片碳同位素组成(δ13C)的季节变化以及与土壤温湿度和气象因子的相关性进行了研究.结果表明:常绿树种叶片δ13C季节间差异不显著,春、夏和秋季的平均值都接近-25.9‰,在-27.0‰～-24.5‰间变化;落叶树种叶片δ13C季节间差异极显著(p=1.97×10-7秋季>夏季,表明绿化树种水分利用效率(WUE)也为春季>秋季>夏季.研究发现:叶片δ13C与比叶面积(SLA)呈显著的负相关(落叶p=6.195×10-8相似文献   

封面说明

<正>鼎湖山生物圈保护区森林景观(张倩媚摄)。熊鑫等通过对鼎湖山森林演替序列植物-土壤碳氮同位素自然丰度的测定,分析了叶片稳定碳同位素比率(δ~(13)C)和稳定氮同位素比率(δ~(15)N)与其叶片元素含量的关系,叶片-凋落物-土壤δ~(13)C、δ~(15)N沿演替方向以及土壤δ~(13)C、δ~(15)N沿剖面深度的变化特征,借此探讨该地区植物群落对资源的利用策略以及森林演替过程中碳氮元素循环过程的变化(本期533–542页)。     

会仙喀斯特湿地三种典型植物叶片碳同位素(δ13C)特征及其指示意义

为探讨会仙喀斯特湿地不同生长环境下植物叶片碳(C)、氮(N)、磷(P)、稳定碳同位素(δ~(13)C)特征及其生态学指示意义,该文以挺水植物芦苇、浮水植物水葫芦和沉水植物金鱼藻为研究对象,分析了三种典型不同生活型植物叶片的δ~(13)C特征及种间和微生境的差异,并基于植物碳同位素与碳酸酐酶显著正相关的二端元模型,估算了植物利用光合作用固定的碳酸氢根离子(HCO3-)的碳量。结果表明:(1)三种植物叶片δ~(13)C的变化范围为-28.47‰～-21.69‰,平均值为-24.83‰,不同生活型植物间δ~(13)C存在差异,金鱼藻水葫芦芦苇。(2)植物δ~(13)C值与叶片C、N和P元素含量间呈显著正相关,与C/N、C/P和N/P呈显著负相关关系,与底泥的有机质、速效氮、总氮、速效磷和总磷含量呈显著正相关。(3)会仙喀斯特湿地三种不同生活型植物叶片N/P平均值为10.34,表现出植物受N、P共同影响的特征。(4)δ~(13)C的变化特征,揭示了三种水生植物可能通过增加磷利用效率来促进低水分利用率环境下的碳的合成,通过提高植物水分利用效率的策略来代偿较低的氮素利用效率。(5)芦苇光合作用固定HCO3-碳量为159.60 t·a~(-1)·km~(-2),水葫芦为10.80 t·a~(-1)·km~(-2),金鱼藻为9.24 t·a~(-1)·km~(-2),平均值为59.88 t·a~(-1)·km~(-2)。会仙喀斯特湿地植物的不同生活型、光合作用途径和生长微环境,是影响叶片δ~(13)C变化的主要因素。     

六道沟流域不同冠层小叶杨光合特性及水分利用效率研究

小叶杨作为六道沟流域植被恢复的优势乔木速生树种,对该区的生态恢复与建设有着至关重要的作用。通过测定六道沟流域生长旺期(8和9月)不同冠层高度下小叶杨叶片的水势、光合气体交换参数、稳定性碳同位素比率(δ~(13)C)和叶片全N全P含量,分析了冠层叶片的δ~(13)C、光合特性指标、叶水势等在不同月份及冠层高度下的变化特征。结果表明:(1)小叶杨8、9月份间叶片光合特性指标净光合速率(P_n)、气孔导度(G_s)、胞间CO_2浓度(C_i)、蒸腾速率(T_r)均随着冠层高度增加而减小。(2)小叶杨叶片δ~(13)C和瞬时水分利用效率(WUEi)均随冠层高度增加而增加,δ~(13)C沿冠层高度的变化范围为-29.81‰~-27.43‰。(3)叶片δ~(13)C与植物的水分利用效率呈正相关关系,8月份和9月份δ~(13)C沿树高的变化幅度分别为2.22‰和2.12‰。研究发现,六道沟流域小叶杨叶片确实受到来自树高所引起的水分胁迫,叶片δ~(13)C能真实反映其长期的水分利用状况,且叶片δ~(13)C的变化是自身遗传特性与环境因子共同作用的结果。     

水肥耦合效应对楸树苗木叶片δ~(13)C的影响

以楸树(Catalpa bungei)无性系004-1苗木为研究对象,采用三因素五水平二次回归通用旋转组合设计进行盆栽试验,通过测定6、7和8月份20个处理楸树苗木叶片碳同位素组成δ~(13)C、总氮含量和总磷含量,建立数学模型,分析土壤水分、施氮量和施磷量的主因子效应、单因素效应及其耦合效应对叶片δ~(13)C的影响,以及叶片碳同位素组成δ~(13)C与其总氮含量和总磷含量的关系。结果表明:(1)楸树苗木叶片δ~(13)C存在明显的月动态变化特征,总体上呈现出6月份高于7、8月份的趋势,20个处理苗木叶片δ~(13)C平均值(6~8月)变化范围介于-29.12‰~-26.60‰之间;(2)土壤水分对叶片δ~(13)C有显著负效应,施氮量对叶片δ~(13)C有显著正效应,并且施氮量主效应大于土壤水分主效应,但施磷量对叶片δ~(13)C无显著主效应;单因素效应分析表明,楸树苗木叶片δ~(13)C随土壤水分或施氮量的增加均呈先增加后减小的"抛物线型"关系;土壤水分×施N量对楸树苗木叶片δ~(13)C有显著耦合负效应,土壤水分和施氮量耦合效应图表明,叶片δ~(13)C随土壤水分降低、施氮量增加而逐渐增加;(3)6月、7月和8月份楸树苗木叶片δ~(13)C与其叶片总氮含量均呈显著正相关关系(P0.05;n=100),但叶片δ~(13)C与总磷含量无显著相关关系(P0.05;n=100)。研究认为,楸树苗木叶片碳同位素组成δ~(13)C随生长期表现出动态变化特征,它受到土壤水分、水氮耦合的显著负向影响,以及施氮量的显著正向影响,可以通过合理水肥配施措施大幅提高楸树苗木δ~(13)C。     

近70年来黄土高原典型植物δ13C值变化研究

对黄土高原地区 4种典型C3 植物狼牙刺 (Sophoraviciifolia) 、辽东栎 (Quercusliaotungensis) 、虎榛子 (Os tryopsisdavidiana) 和酸枣 (Zizyphusjujubavar.spinosa) 样品稳定性碳同位素组分 (δ¹³ C) 进行分析, 研究了从 2 0世纪 30年代至今近 70年中不同年代植物δ¹³ C值的变化。结果表明, 在近 70年中, 4种植物δ¹³ C值变化范围为- 2 5.0 5‰~ - 2 9.75‰, 平均值为 - 2 7.0 4‰。 4种植物叶片δ¹³ C值均呈下降趋势, 表明随气候环境变化, 近 70年4种植物的水分利用效率 (WUE) 均呈降低趋势。但不同植物叶片δ¹³ C值下降幅度不同 :狼牙刺和辽东栎叶片δ¹³ C值下降非常明显, 虎榛子叶片δ¹³ C值下降也较明显, 而酸枣叶片δ¹³ C值下降不明显。 4种植物δ¹³ C值的降低率分别为 14.6 5 %、14.4 6 %、11.99%和 2.4 4 %, 说明不同植物对气候环境因子的敏感性不同, 具有不同的适应环境变化的策略, 酸枣是 4种植物中耐旱能力较强, WUE较高的物种。     

灵石山不同海拔米槠林优势种叶片δ13C值与叶属性因子的相关性

对灵石山海拔157-842 m(分9个海拔梯度,分别记为A1-A9)的米槠林优势种叶片δ13C值的特征及其与属性因子的关系进行分析,结果表明,灵石山米槠林优势种叶片δ13C的分布范围为(-28.806‰—-34.399‰),平均值为(-30.885±1.205)‰,叶片δ13C值与比叶面积(SLA)、叶片N含量、2年生K含量、Na含量、Mg含量、Ash(灰分)含量呈显著负相关,与2年生叶片Chl(叶绿素)含量、叶片P含量、叶片Ca含量、叶片干物质含量(LDMC)含量呈显著正相关,与不同叶龄Fe、Zn含量相关性不显著,与1年生和2年生叶片Mn含量分别呈负相关和正相关.不同优势种植物叶片δ13C丰度差异可以反映植物生理状况的变化.不同海拔梯度上叶片属性特征在一定程度上反映和影响了以米槠为建群种和优势种的灵石山常绿阔叶林叶片δ13C的特征.     

Allocation of reserve-derived and currently assimilated carbon and nitrogen in seedlings of Helianthus annuus under sub-ambient and elevated CO growth conditions

Here, we analysed the transition from heterotrophic to autotrophic growth of the epigeal species sunflower (Helianthus annuus), and how transition is affected by CO(2). Growth analysis and steady-state (13)CO(2)/(12)CO(2) and (15)NO(3) (-)/(14)NO(3) (-) labelling were used to quantify reserve- and current assimilation-derived carbon (C) and nitrogen (N) allocation to shoots and roots in the presence of 200 and 1,000 micromol CO(2) mol(-1) air. Growth was not influenced by CO(2) until cotyledons unfolded. Then, C accumulation at elevated CO(2) increased to a rate 2-2.5 times higher than in sub-ambient CO(2) due to increased unit leaf rate (+120%) and leaf expansion (+60%). CO(2) had no effect on mobilization and allocation of reserve-derived C and N, even during the transition period. Export of autotrophic C from cotyledons began immediately following the onset of photosynthetic activity, serving roots and shoots near-simultaneously. Allocation of autotrophic C to shoots was increased at sub-ambient CO(2). The synchrony in transition from heterotrophic to autotrophic supply for different sinks in sunflower contrasts with the sequential transition reported for species with hypogeal germination.     

Turnover of glucose and acetate coupled to reduction of nitrate, ferric iron and sulfate and to methanogenesis in anoxic rice field soil

Turnover of glucose and acetate in the presence of active reduction of nitrate, ferric iron and sulfate was investigated in anoxic rice field soil by using [U-(14)C]glucose and [2-(14)C]acetate. The turnover of glucose was not much affected by addition of ferrihydrite or sulfate, but was partially inhibited (60%) by addition of nitrate. Nitrate addition also strongly reduced acetate production from glucose while ferrihydrite and sulfate addition did not. These results demonstrate that ferric iron and sulfate reducers did not outcompete fermenting bacteria for glucose at endogenous concentrations. Nitrate reducers may have done so, but glucose fermentation may also have been inhibited by accumulation of toxic denitrification intermediates (nitrite, NO, N(2)O). Addition of nitrate resulted in complete inhibition of CH(4) production from [U-(14)C]glucose and [2-(14)C]acetate. However, addition of ferrihydrite or sulfate decreased the production of (14)CH(4) from [U-(14)C]glucose by only 70 and 65%, respectively. None of the electron acceptors significantly increased the production of (14)CO(2) from [U-(14)C]glucose, but all increased the production of (14)CO(2) from [2-(14)C]acetate. Uptake of acetate was faster in the presence of either nitrate, ferrihydrite or sulfate than in the unamended control. Addition of ferrihydrite and sulfate reduced (14)CH(4) production from [2-(14)C]acetate by 83 and 92%, respectively. Chloroform completely inhibited the methanogenic consumption of acetate. It also inhibited the oxidation of acetate, completely in the presence of sulfate, but not in the presence of nitrate or ferrihydrite. Our results show that, besides the possible toxic effect of products of nitrate reduction (NO, NO(2)(-) and N(2)O) on methanogens, nitrate reducers, ferric iron reducers and sulfate reducers were active enough to outcompete methanogens for acetate and channeling the flow of electrons away from CH(4) towards CO(2) production.     

Glycine metabolism in intact leaves by in vivo 13C and 15N labeling

Solid-state (13)C NMR measurements of intact soybean leaves labeled by (13)CO(2) (at subambient concentrations) show that excess glycine from the photorespiratory C(2) cycle (i.e. glycine not part of the production of glycerate in support of photosynthesis) is either fully decarboxylated or inserted as (13)C-labeled glycyl residues in proteins. This (13)C incorporation in leaf protein, which is uniformly (15)N labeled by (15)NH(4)(15)NO(3), occurs as soon as 2 min after the start of (13)CO(2) labeling. In those leaves with lower levels of available nitrogen (as measured by leaf nitrate and glutamine-glutamate concentrations), the excess glycine is used primarily as glycyl residues in protein.     

Dispersion modelling and measurement of emissions from the co-combustion of meat and bone meal with peat in a fluidised bed

Due to the ban on meat and bone meal (MBM) as an animal feed, combustion with energy recovery has been considered a viable alternative usage for the mounting stocks of MBM. The effects of the co-combustion of MBM and peat on flue gas emissions and fluidisation were studied using a bubbling fluidised bed (BFB) test facility (20 kW). The dispersion of emissions such as nitrogen dioxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO), hydrogen chloride (HCl) and particulates was investigated for a proposed site and compared to the relevant national and international regulations. Concentrations of NO2, CO and HCl were less than 10% of legislative and guideline thresholds while ground level concentrations of SO2 were also below relevant EU and world guidelines. The results indicate the potential for using MBM as a co-fuel with peat in a BFB while maintaining high air quality standards.     

Reaction of Airborne Rhizobium meliloti to Some Environmental Factors

Survival of Rhizobium meliloti 102F5 in aerosols at 20 C was maximal at high relative humidity (RH) and minimal at low RH. Relatively high concentrations of NO(2), SO(2), or formaldehyde were needed to significantly reduce viability of R. meliloti in aerosols at 50% RH. Except for the reduction in activity of formaldehyde by SO(2), there was no additive or antagonistic effect of mixing pollutants. High environmental RH enhanced bactericidal activity of NO(2) and SO(2). High RH minimized and low RH accentuated the biological effect of ultraviolet light of 300 to 400 nm wavelength.     

The influence of root assimilated inorganic carbon on nitrogen acquisition/assimilation and carbon partitioning

Understanding of the influences of root-zone CO2 concentration on nitrogen (N) metabolism is limited. The influences of root-zone CO2 concentration on growth, N uptake, N metabolism and the partitioning of root assimilated 14C were determined in tomato (Lycopersicon esculentum). Root, but not leaf, nitrate reductase activity was increased in plants supplied with increased root-zone CO2. Root phosphoenolpyruvate carboxylase activity was lower with NO3(-)- than with NH4(+)-nutrition, and in the latter, was also suppressed by increased root-zone CO2. Increased growth rate in NO3(-)-fed plants with elevated root-zone CO2 concentrations was associated with transfer of root-derived organic acids to the shoot and conversion to carbohydrates. With NH4(+)-fed plants, growth and total N were not altered by elevated root-zone CO2 concentrations, although 14C partitioning to amino acid synthesis was increased. Effects of root-zone CO2 concentration on N uptake and metabolism over longer periods (> 1 d) were probably limited by feedback inhibition. Root-derived organic acids contributed to the carbon budget of the leaves through decarboxylation of the organic acids and photosynthetic refixation of released CO2.     

Biofixation of CO2 from synthetic combustion gas using cultivated microalgae in three-stage serial tubular photobioreactors

Coal is the most abundant of the fossil fuels, with reserves estimated at 102 billions of tons. The feasibility of using coal as a fuel depends upon reducing emissions of gas when it is burnt, such as carbon dioxide (CO2), sulfur oxides (SO(x)), and nitrogen oxides (NO(x)). The removal of CO2 with microalgae may be one of the most efficient ways of reducing this gas, without the need for radical changes in the world's energy supply and production methods. Spirulina sp. LEB-18 and Scenedesmus obliquus LEB-22 were cultivated in serial tubular photobioreactors, with the aim of measuring the potential of CO2 biofixation and the resistance of the microalgae to SO2 and NO. Spirulina sp. and S. obliquus had CO2 biofixation scores of 0.27 and 0.22 g L(-1) d(-1), respectively. Both microalgae were resistant to SO2 and NO, and grew during the 15 d they were cultivated, which proves that using microalgae is an efficient method of biofixation of CO2 emitted when fossil fuels are burnt.     

Isotope labeling and microautoradiography of active heterotrophic bacteria on the basis of assimilation of 14CO(2)

Most heterotrophic bacteria assimilate CO(2) in various carboxylation reactions during biosynthesis. In this study, assimilation of (14)CO(2) by heterotrophic bacteria was used for isotope labeling of active microorganisms in pure cultures and environmental samples. Labeled cells were visualized by microautoradiography (MAR) combined with fluorescence in situ hybridization (FISH) to obtain simultaneous information about activity and identity. Cultures of Escherichia coli and Pseudomonas putida assimilated sufficient (14)CO(2) during growth on various organic substrates to obtain positive MAR signals. The MAR signals were comparable with the traditional MAR approach based on uptake of (14)C-labeled organic substrates. Experiments with E. coli showed that (14)CO(2) was assimilated during both fermentation and aerobic and anaerobic respiration. The new MAR approach, HetCO(2)-MAR, was evaluated by targeting metabolic active filamentous bacteria, including "Candidatus Microthrix parvicella" in activated sludge. "Ca. Microthrix parvicella" was able to take up oleic acid under anaerobic conditions, as shown by the traditional MAR approach with [(14)C]oleic acid. However, the new HetCO(2)-MAR approach indicated that "Ca. Microthrix parvicella," did not significantly grow on oleic acid under anaerobic conditions with or without addition of NO(2)(-), whereas the addition of O(2) or NO(3)(-) initiated growth, as indicated by detectable (14)CO(2) assimilation. This is a metabolic feature that has not been described previously for filamentous bacteria. Such information could not have been derived by using the traditional MAR procedure, whereas the new HetCO(2)-MAR approach differentiates better between substrate uptake and substrate metabolism that result in growth. The HetCO(2)-MAR results were supported by stable isotope analysis of (13)C-labeled phospholipid fatty acids from activated sludge incubated under aerobic and anaerobic conditions in the presence of (13)CO(2). In conclusion, the novel HetCO(2)-MAR approach expands the possibility for studies of the ecophysiology of uncultivated microorganisms.     

小兴安岭主要乔、灌木燃烧过程的烟气释放特征

测定了小兴安岭林区凉水林场10种乔木和9种灌木可燃物燃烧过程中释放的CO₂、CO、xHy、SO₂和NO等气体含量,计算了不同可燃物的气体释放量及排放因子.结果表明：乔木和灌木可燃物试样燃烧过程中释放的CO₂、含碳气体总量和5种气体总量的平均值分别为1 277.04和1 149.06 mg·g^-1、1 476.27和1 147.18 mg·g^-1、1 486.21和1 459.67 mg·g^-1,乔木均大于灌木;乔木和灌木的CO、NO和SO₂释放量平均值分别为231.58和282.93 mg·g^-1、3.61和5.03 mg·g^-1、6.32和7.46 mg·g^-1,灌木均大于乔木;乔木和灌木的CO₂、CO排放因子分别为2.8853和2.7718、0.4558和0.2425,乔木大于灌木.     

Characterization of wet and dry deposition in the downwind of industrial sources in a dry tropical area

An atmospheric deposition study was conducted in the downwind of Shaktinagar Thermal Power Plant (STPP), Renusagar Thermal Power Plant (RTPP), and Anpara Thermal Power Plant (ATPP), at Singrauli region, Uttar Pradesh (UP), India to characterize dry and wet deposition in relation to different pollution loading. During the study period, dry and wet depositions and levels of gaseous pollutants (SO2 and NO2) were estimated across the sites. Dry deposition was collected on a monthly basis and wet deposition on an event basis. Depositions were analyzed for pH, nitrate (NO3-), ammonium (NH4+), and sulphate (SO4(2-)) contents. Dry deposition rate both collected as clearfall and throughfall varied between 0.15 to 2.28 and 0.33 to 3.48 g m(-2) day(-1), respectively, at control and maximally polluted sites. The pH of dry deposition varied from 5.81 to 6.89 during winter and 6.09 to 7.02 during summer across the sites. During the rainy season, the mean pH of clear wet deposition varied from 6.56 to 7.04 and throughfall varied from 6.81 to 7.22. The concentrations of NO2 and SO2 pollutants were highest during the winter season. Mean SO2 concentrations varied from 18 to 75 g m(-3) at control and differently polluted sites during the winter season. The variation in NO2 concentrations did not show a pattern similar to that of SO2. The highest NO2 concentration during the winter season was 50 g m(-3), observed near RTPP. NO2 concentration did not show much variation among different sites, suggesting that the sources of NO2 emission are evenly distributed along the sites. The concentrations of NH4+, NO3-, and SO4(2-) ions in dry deposition were found to be higher in summer as compared to the winter season. In dry deposition (clearfall) the concentrations of NH4+, NO3-, and SO4(2-) varied from 0.13 to 1.0, 0.81 to 1.95, and 0.82 to 3.27 mg l(-1), respectively, during winter. In wet deposition (clearfall), the above varied from 0.14 to 0.74, 0.81 to 1.82, and 0.67 to 2.70 mg l(-1), respectively. The study clearly showed that both dry and wet depositions varied between the sites and season, suggesting significant impact of industrial activities in modifying the atmospheric input. The nonacidic deposition suggests that there is no threat of acidification of the receiving ecosystem at present.