Variation of toxaphene indicator compounds in fish from single fishing grounds: conclusions for sampling

The levels of three toxaphene indicator compounds were determined in individual lots of herring, redfish, Greenland halibut and farmed salmon. Concentration levels of the three marine fish species were characterised by a right-skewed frequency distribution whereas residue concentrations in farmed salmon were normally distributed. The toxaphene concentrations in the edible part of redfish, herring and Greenland halibut were found to be positively correlated to the sizes and thus to age. As results show, for representative sampling of a landed catch, not more than 10 individual fishes from typical size classes of a lot are necessary for a pooled sample.     

Investigation on the photoreactions of nitrate and nitrite ions with selected azaarenes in water

The photoreactions of selected azaarenes with nitrate and nitrite ions were investigated under irradiation at lambda = 313 nm. The excitation of both anions leads to several photochemical reactions forming mainly hydroxyl radicals and nitrogen oxides. The purification capability of natural waters i.e. the oxidation of inorganic and organic substances results from the formation of hydroxyl radicals. Nitrated isomers of azaarenes were found among the main products of the investigated photoreactions. The nitrogen oxides were responsible for the production of nitrated derivatives which possess a high toxic potential. Their formation was explained by the parallel occurance of two mechanism, a molecular and a radical one. The molecular mechanism became more important with increasing ionisation potentials of the azaarenes. The spectrum of oxidized products corresponded to the one got in the photoreactions of azaarenes with hydrogen peroxide. The formation of several oxidation and nitration products of the pyridine ring with its low electron density was explained by the reaction of excited states of azaarenes. The photoreactions with nitrite ions only led to the formation of oxidized and nitrated products. Nitroso products were not formed. The reactivity of nitrogen monoxide is too low for its reaction with the azaarenes.     

Effect of manganese on the concentration of amino acids in different regions of the rat brain

The present study was designed to determine if chronic exposure of weanlings and adult rats to Mn produces significant alterations in amino acid concentrations in different regions of the rat brain. Weanling (30 day old) and adult (90 day old) male rats were exposed to 10 and 20 mg Mn/kg body weight per day, by gavage, for 30 days. Forty-eight hours after the last dose, animals were sacrificed by decapitation and brains were dissected into different regions to determine the concentration of amino acids by HPLC/EC. A dose dependent decrease in body weight gain was found in the adult, but not in the weanling rats. Significant increases occurred in concentrations of aspartate, glutamate, glutamine, taurine and gamma-aminobutyric acid (GABA) in the cerebellum of the adult rats dosed with 20 mg/kg per day, Mn. A significant decrease in the concentration of glutamine was observed in caudate nucleus and hippocampus of weanling rats dosed with 10 mg/kg, Mn. These data suggest that chronic Mn exposure can produce a decrease in body weight gain in adult rats and alterations in amino acids in different regions of weanling and adult rat brains.     

以色列的地震危险性

<正> 1 地震危险性评定历史早期的Sieberg(1932),shalem(1952)和Arieh(1967)进行了与地震烈度有关的地震危险性评定。Arieh和Feldman(1985)编制了以色列的地震烈度图。Shapira(1981,1983a,1983b)和Ben-Menahem等(1982)给出了以色列及其邻区的概率地震危险性评定.Shapira应用的是一种称作直接统计法和蒙特卡洛算法。Ben-Menahem等(1982)主要计算了0.05g的地面峰值加速度等危险性曲线.Vered(1978)给出了这个地区可能最大震级的估计。由Arieh Rabinowitz(1989)最近所作的地震危险性评定是对过去工作的定期修改.在以色列规     

了解过去是通向未来的方舟

<正> 前言70年代一个重要的地质研究领域问世了。这个领域和许多新的科学领域一样是根据实际需要而创立的。这个领域随着环境问题而逐渐发展起来,因此,它继承了多年的传统,包括中世纪晚期的天文学和第二次世界大战以后兴起的粒子或空间物理学这样一些领域。一般从地质学的角度来说,我们总是尽量想了解地球的过去,而且常常利用均变说定律,即现在是了解过去的钥匙。这个新领域利用现在和过去来预测未来的地质发展趋势或各种地质事件。地质预测涉及到三个主要的课题:     

在能源结构及利用中减少SO_2及NO_x排放量的对策

1.前言有几种削减有害废物排放量的重要途径。A代表所有的一次能源E中某种化合物的总体排放量 A=∑E×C×R (1) 式中C是燃烧单位能源量的化合物生成量,R是净化设备产生的削减因子,另外, E=∑a×ex效率 (2) 式中a表示活动水平,e是指a在每个部门中的单位最终能源,效率是指把一次能源转化成适合于使用的最终形式的效率。∑(总和)则包括社会上全部活动之和。当然,公式通过每个领域的平均值将现实生活简化了。排放量能受到上述公式中的任何     

南非芬什金伯利岩中产出的两个含金刚石的橄榄岩捕虏体

<正> 尽管金刚石有重大的经济意义,并且每年回收大量金刚石,但其天然形成过程仍有争论。虽然假定大多数金刚石是岩浆成因的,并且与金伯利岩事件有联系,但是金伯利岩中某些捕虏体内金刚石的存在表明,至少有些金刚石是捕获晶。这种非同源成因的金刚石的比例是目前争论问题之一。     

Cytotoxicity to alveolar macrophages of airborne particles and waste incinerator fly-ash fractions

A waste incinerator fly ash was separated into different grain-size fractions by sieving and sedimentation in butanol. The element content of each fraction was determined by atomic absorption and emission spectrometry. The fly-ash fractions, an eluted fine fly-ash fraction and an eluted airborne dust were analysed microscopically for particle size and numbers, together with standard quartz DQ 12 and three element-analysed airborne dusts. Rabbit alveolar macrophages, isolated by lung lavage, were incubated for 24 h with the particulates, the two eluates and a mixed element compound solution corresponding to the element concentrations of one airborne dust. At the end of incubation, the activities of lactate dehydrogenase, N-acetyl-beta-glucosaminidase, beta-galactosidase and acid phosphatase were determined in medium and cell lysates. Cytotoxicity was expressed as ratio of extracellular to total LDH (lactate dehydrogenase) activity. Release of N-acetyl-beta-glucosaminidase and beta-galactosidase was correlated positively with LDH release, whereas the total activity of acid phosphatase decreased with increasing LDH release. Cytotoxicity of the dusts was correlated with particle numbers, and As, Sb and Pb contents. The contribution of As to particle toxicity is discussed. Eluates of dusts did not affect rabbit alveolar macrophage viability.     

科利夫巴斯“五一”矿床铁质石英岩中碱性交代岩的矿物——地球化学分带的特点

<正> 前寒武纪铁-硅建造中的碱性交代岩,乃为含霓石、钠闪石和钠长石的岩石,这类岩石在矿物组成和化学成分以及结构构造方面均与原生铁质石英岩和页岩有着天壤之别。许多学者把此类岩石看作是前寒武纪铁-硅建造所固有的一套岩类,它们或是在外来热液进入铁质岩后在热液的作用下形成的,或是铁质岩层内部物质本身进行再分配的结果。     

国际矿物协会矿石显微镜委员会关于符号和定义的报告

<正> 对于各种光学类别的不透明矿物的反射率的性质,目前使用的符号是多样的和矛盾的。为了调研这些符号和推荐一套符号系统,1974年国际矿物协会(IMA)的矿石显微镜委员会(COM)建立了符号和定义委员会。委员会曾提供一个暂时报告,并在1978年新西伯利亚的COM会议上通过。然而,这报告的发表被推迟到和定量资料档案的编辑委员会的报告一起公布。下面是在1980年奥尔良的COM会议上通过的供发表的修改报告。