Effects of acid deposition on crops and forests

Summary Acid deposition includes the gases, sulphur dioxide and nitrogen oxides, and their derivative acids which are dissolved in various forms of precipitation. The effects of both dry and wet deposition on crops and forests are reviewed, including interactions between these two categories of pollutant. Particular emphasis is given to the current forest decline in central Europe, including the possible role of ozone.     

Effects of acid precipitation on reproduction in birds

Summary Acidification in aquatic habitats reduces the reproductive success of both piscivorous and non piscivorous birds, mainly by reducing the food supply. Piscivorous birds find some compensation in an increased transparency of the water, non piscivorous birds in less competition for invertebrate prey by fish. Acidification in forests often has large impacts on insect populations but how this affects forest birds is unknown. Some woodpeckers and nuthatches temporarily benefit from an increase in standing dead timber. In advanced stages of forest dieback the breeding density of forest birds is very much reduced, but species of open woodland increase. Calcium deficiency reduces the reproductive output of some passerine species, but the extent of this phenomenon is unknown. Increased exposure to toxic metals has reduced the reproductive success of some lake dwelling species. It is difficult to assess the effect of acid precipitation on birds since acidification affects ecosystems in many ways, the evidence is largely correlative and reliable estimates of the population size are often lacking. Future studies should concentrate on carefully selected indicator species suitable for detailed data collection.Interested readers may also wish to refer to EXPERIENTIA's April and May 1986 issues featuring the 2-part Multi-author Review The Ecological Effects of Acid Deposition coordinated by O. Ravera.     

The distribution of acid deposition in Germany

Summary The distribution of acid deposition by atmospheric precipitation in the Federal Republic of Germany is discussed, based on investigations of the wet H⁺-deposition during the five years 1980–1984, using a network of 16 automated samplers of our own construction located in various categories of ecosystems. Analytical problems of sampling and the electrometric determination of pH in rainwater are briefly discussed. Results for the average amounts of precipitation, the average H⁺-concentrations and average H⁺-depositions in the 16 typical regions of the Federal Republic of Germany are compared and the influences of meteorological parameters are discussed. An increase of the H⁺-concentration and H⁺-deposition values has been observed from 1980 onwards with a maximum in 1981 and a slow decrease in the next two years. The comparison of the values found for rural regions with those for more significantly polluted regions shows that in the latter regions the removal of H⁺-ions by wash-out is more effective. Whereas in the Ruhr region the pH is shifted to more acid values, due to the wash-out of acid particles and aerosols, in regions with metallurgical industry the pH is shifted to more alkaline values due to the wash-out of alkaline particles. In general the free acid in rain and snow is rather uniformly distributed over the whole area as a result of mesoscalic transport of the acid precursors SO₂ and NO_x and the concomitant formation of acid in the cloud droplets leading to acid deposition by rain-out. The composition of rainwater and the possibility of determining the proportion of the acid anions in rain which are of anthropogenic origin is briefly discussed.Deseased (May 12th, 1985).     

Effects of temperature and pressure on the structural and optical properties of ZnO films grown by pulsed laser deposition

ZnO thin films were deposited on fused silica via pulsed laser deposition (PLD) at substrate temperatures from 300°C to 800°C and ambient oxygen pressures ranging from 10?2 mTorr to 240 mTorr. X-ray diffraction (XRD) and Raman spectra indicated that wurtzite ZnO was obtained in all cases. The highly c-oriented ZnO films were obtained for oxygen pressures above 11 mTorr. The room-temperature photoluminescence (PL) spectra demonstrated that all the films exhibited strong near-band-edge (NBE) emission, while d...     

Effects of cortisone and ethylenediamine-tetraacetic acid on deposition of promethium (Pm147)

Zusammenfassung Junge erwachsene weibliche Ratten, welche Einspritzungen von radioaktivem Promethium (Pm¹⁴⁷) erhalten hatten, wurden mit dem Kalziumsalz von Äthylendiamintetraessigsäure (CaEDTA) und/oder Cortison behandelt. Die Behandlungen vergrösserten die Blutkonzentrationen von Pm¹⁴⁷ ein wenig. CaEDTA-Behandlung verkleinerte die Menge von Promethium in der Leber um 20%, aber in anderen typischen weichen Zellgeweben und im Schenkel veränderte keine der Behandlungen die allgemeine Verteilung von Pm¹⁴⁷. Das autoradiographische Bild zeigt, dass die örtliche Verteilung von Pm¹⁴⁷ derjenigen von anderen lanthaniden Elementen ähnlich ist.     

Effects of water acidification on the distribution pattern and the reproductive success of amphibians

Summary Nine amphibian species were encountered in poorly buffered waters of The Netherlands (alkalinity 1 meq·l^–1). These soft water systems are highly sensitive to acidifying precipitation. The number of species as well as the percentage of waters which harbour amphibian populations are strongly reduced in the extremely acid pH-class . The reproductive success of amphibians is negatively affected by low pH. The eggs become heavily infested with fungi (Saprolegniaceae). In acidifying systems many physico-chemical parameters are significantly correlated with the pH of the water. Strongly acidified waters are characterized by low alkalinity, conductivity and ionic content but high acidity and high concentrations of (heavy) metals and ammonium and a high relative sulphate concentration. Culture experiments with eggs and larvae ofRana arvalis. Rana esculenta, Rana temporaria andBufo bufo show that apart from the pH, elevated aluminium, cadmium and ammonium contents may also affect the reproductive success of amphibians.     

基于可见/近红外光谱的土壤有机质含量预测

应用可见/近红外光谱技术对土壤有机质含量进行了定量分析和预测,为土壤肥力快速测定和评价提供依据.利用ASD FieldSpec 3 Hi-Res光谱仪对116份不同有机质含量的土壤样本进行光谱测量,系统分析了土壤有机质含量与350～2500 nm波段范围光谱反射率之间的关系.利用PLS和小波-BP神经网络对350～2500 nm整个波段范围和剔除水波段的光谱数据进行分析.两种建模方法的结果均表明剔除水波段的预测效果较好,其中,PLS模型预测的相关系数R为0.8416,均方根误差RMSEP为0.2848,相对分析误差RPD为1.7768,WT-BP神经网络模型预测的R为0.9167,RMSEP为0.2196,RPD为2.3043.预测结果表明,PLS模型可以对土壤有机质含量进行粗略估测,而BP神经网络可实现较精确的预测.     

一种土壤团聚体稳定性评估系统

团聚体稳定性是土壤结构的重要属性.国内外团聚体稳定性量化研究较少,而能够定量评估团聚体稳定性的系统也少.鉴于该研究现状,本文设计了一套土壤团聚体稳定性评估系统,它利用功率超声粉碎土水溶液中土壤团聚体,通过实时监测土水溶液温度和超声系统输入功率的变化,并根据能量转化与守恒定律计算出土壤超声分散能量,进而确定土壤团聚体的稳定性.在实验室环境下对澳大利亚新南威尔士州Namoi和Narrabri的两种不同质地土样进行测量,其土壤分散能量分别为328和207 J·g^-1,前者土壤结构更稳定.     

Lunar soil and Zagami meteorite inhibit biosynthesis of itoic acid,a siderophore

Summary Lunar soil, Zagami meteorite, and Gorda Ridge ocean basalt inhibited the synthesis of iotic acid and coproporphyrin III in iron-deficientBacillus subtilis cultures. Synthetic ilmenite did not. The results indicated that the three natural samples served as sources of iron for the organism, but the ilmenite did not.     

升高CO2浓度和温度对针叶林的影响以及在川西亚高山针叶林研究中的展望

以CO2浓度和温度升高为主要特征的全球气候变化受到了世界各国科学家们的普遍关注。目前已经有大量关于森林生态系统对全球变化响应的研究报道和综述性文章,涉及分子、生理生态、种群和群落生态以及区域和全球尺度等微观和宏观领域的研究内容,因而要想对森林生态系统对全球变化的响应研究进行全面的综述是相当困难的。因此,本文只简要评述了森林生态系统对升高CO2浓度和温度响应研究中的诸如CO2浓度和温度升高对森林生长和生产力的影响、森林生态系统物种组成和多样性对升高CO2浓度和温度的响应、植被变化与全球碳循环的互动以及气候变化与森林生态系统生物地球化学循环的关系等几个热点问题。川西亚高山针叶林区为我国的第二大林区,地处高山峡谷地带,是全球变化的敏感地带。相对简单的植物群落结构、较低的物种丰富度和多样性、巨大的冷冻土壤碳库、不同演替阶段和功能的植物群落组合以及分布于林线附近的邻接效应等为研究针叶林系统对升高CO2浓度和温度的响应提供了良好的天然实验室。针叶林生产力、植物群落物种组成和多样性以及土壤碳氮过程等对升高CO2浓度和温度的响应对于预测未来气候变化下针叶林系统的生态过程具有重要意义。     

The effects of acid deposition on benthic animals in lakes and streams

Cellular and Molecular Life Sciences -     

Effects of the virulence plasmid ColV,I-K94 on the sensitivity ofEscherichia coli to putative environmental inhibitory agents

Summary Derivatives ofEscherichia coli carrying the virulence plasmid, ColV, I-K94 were more resistant than the ColV^– parents to phage Mel but were more sensitive to the hydrophobic inhibitors deoxycholate, erythromycin and lysozyme. The basis for these changes in sensitivity has been examined in ColV⁺ mutants with altered colicin or VmpA protein levels and in ColV⁺ strains with repressed transfer properties.The authors wish to thank the Fondacion Gran Marischal de Ayacucho and the Central Research Fund of the University of London for financial support.     

Effects of antithymic reticuloepithelial cells serum on the levels of circulating thymic factor and on the sensitivity to azathioprine of spleen spontaneous rosette-forming cells

Summary Swiss mice treated with an antithymic reticuloepithelial cells serum (ATRES) showed a drastic and prolonged depression of the serum thymic factor. A similar but less pronounced effect was also observed following the administration of the antithymocyte (ATS) and the antilymphocyte (ALS) sera. Conversely, the azathioprine sensitivity of spleen spontaneous rosette-forming cells was highly modified by the ATRES but not by the ATS or the ALS. The probable mechanisms of such effects are discussed.     

Effects of the virulence plasmid ColV, I-K94 on the sensitivity of Escherichia coli to putative environmental inhibitory agents

Derivatives of Escherichia coli carrying the virulence plasmid, ColV, I-K94 were more resistant than the ColV- parents to phage Mel but were more sensitive to the hydrophobic inhibitors deoxycholate, erythromycin and lysozyme. The basis for these changes in sensitivity has been examined in ColV+ mutants with altered colicin or VmpA protein levels and in ColV+ strains with repressed transfer properties.     

Effects of monovalent cations on the responses of motoneurones to different groups of amino acid excitants in frog and rat spinal cord

Summary Classification of excitatory amino acids into different groups, of possible value for transmitter identification, can be made on the basis of the differential effects of altered external [Na⁺] and [K⁺] on motoneurone depolarization in frog and immature rat spinal cord.Acknowledgments. We thank Mr D. J. Oakes for skilled technical assistance. This work was supported from the Medical Research Council.