硒酸钠和亚硒酸钠对长春花细胞悬浮生长的影响

研究了硒化合物对长春花(C.roseus)细胞悬浮生长的影响.在pH5.5培养介质中,当Se(Ⅵ)>0.5ppm或Se(Ⅳ)>0.6ppm时,将抑制C.roseus细胞悬浮生长,其致死浓度分别是100ppm Se(Ⅵ)和2.0ppm Se(Ⅳ).C.roseus对硒化合物有效强的富集作用.硒化合物的毒性和培养介质的pH值有关.在本试验条件下,硒酸钠和亚硒酸钠对Hg~(2+)无拮抗作用.     

Dietary exposure to di-isobutyl phthalate increases urinary 5-methyl-2′-deoxycytidine level and affects reproductive function in adult male mice

Phthalates are a large family of ubiquitous environmental pollutants suspected of being endocrine disruptors. Epidemiological studies have associated phthalate metabolites with decreased reproductive parameters and linked phthalate exposure with the level of urinary 5-methyl-2′-deoxycytidine(5mdC, a product of methylated DNA). In this study, adult male mice were exposed to 450 mg di-isobutyl phthalate(DiBP)/(kg·day) via dietary exposure for 28 days. Mono-isobutyl phthalate(Mi BP, the urinary metabolite) and reproductive function parameters were determined. The levels of 5mdC and 5-hydroxymethyl-2′-deoxycytidine(5hmdC) were measured in urine to evaluate if their contents were also altered by DiBP exposure in this animal model. Results showed that DiBP exposure led to a significant increase in the urinary 5mdC level and significant decreases in sperm concentration and motility in the epididymis, accompanied with reduced testosterone levels and downregulation of the P450 cholesterol side-chain cleavage enzyme(P450scc) gene in the mice testes. Our findings indicated that exposure to DiBP increased the urinary 5mdC levels,which supported our recent epidemiological study about the associations of urinary 5mdC with phthalate exposure in the male human population. In addition, DiBP exposure impaired male reproductive function, possibly by disturbing testosterone levels; P450scc might be a major steroidogenic enzyme targeted by DiBP or other phthalates.     

元古宙海水的稳定同位素组成发生过大的变化了吗?

古元古代罗克内斯特组(1.93～1.89Ga)的海相碳酸盐相对于较年轻且形成于类似沉积环境的新元古代海相碳酸盐大量亏损δ~(18)O(约8‰)。广海海相组分的同位素数据叠加了两种同位素趋势。第一种趋势包括早期潮坪沉积物的稳定化作用,以及富δ~(18)O蒸发孔隙流体可能发生的回流型白云岩化作用。对于在同位素成分上δ~(18)O值较低的第二种趋势,它是广海海相与大气降水(混合带)接触或在埋藏的较高温度条件下白云岩化作用期间形成的,由此导致了块状孔隙吸留胶结物的沉淀。 最富集同位素的鲕粒均为保存最好的标准海相组分,因而可能表明海水的δ~(18)O值在1.9Ga时约为-9.75‰±1.0‰(SMOW)。为了解释所推论的海水δ~(18)O值在1.9～1.0Ga期间存在8‰的正向漂移,海水的这一组成要求在高温下海水与玄武岩之间存在氧同位素交换平衡以及低温风化作用有过较大的变化。很可能亏损的δ~(18)O值表明在1.9Ga时表层海水具有大约30～35°C的较高温度。其重碳同位素δ~(13)C值为+1.75‰,比先前根据全岩数据所报道的新元古代海水更富集δ~(13)C。     

爱尔兰的地震危险性

<正> 1 地震危险性评定历史关于不列颠与爱尔兰,Salibury勋爵在1883年写道:“三个王国中最不可能一致的部分是爱尔兰,因此,爱尔兰有一幅醒目的地图”(Andrews,1975)。就地震活动来说,爱尔兰是个极不一致的地方——没有地震危险性图。的确,在爱尔兰还没有出版过仪器定位的地震分布图。     

环境监测—一个实例研究

一家公司在现有工厂中引进一种新制造工艺时,也需要进行新的化学品贮存和分配、水处理、废水处理和废气处理。该公司有强有力的法人环境政策,虽然并没有义务这样做,但该公司仍然实施了环境影响评价和环境监测计划。该监测计划始于新工艺开工前九个多月,提供了有关大气、土壤、地下水和地表水的质量的基线数据。 监测继续进行,以便评价该工艺的影响,并为废水和大气排放物治理装置的设计提供有用信息。自从原工艺采用以来,制造技术上已经有了二个重大变化。这些变化也需要进一步监测,主要是废水水质和大气排放方面的监测,以便改进其处理工艺。     

MIDREX直接还原炼铁——无损环境之途径

引言近年来,在全世界各炼钢厂的规模上,出现了一个引人注目的趋势:从大规模的年产数百万吨钢的大型钢厂趋向于较小的地方小钢联。各种环境考虑已经强有力地左右了各种流程的选择,这就是引起炼钢容量变动的咄咄逼人的经济和社会原因。在用于地方炼钢工业的许多综合流程中,以天然气为主要还原剂的直接还原法结合电弧炼钢,对环境影响最小。继Oregon钢铁厂Midrex直接还原车间于1969年建立之后,Portland厂Midrex装置也已勤奋地开始工作,使环境损害减少至     

Evidence of biological recovery in acid-stressed lakes near Sudbury, Canada

Reductions in the emissions of SO2 and trace metals from the Sudbury smelters have resulted in substantial improvements in water quality in many surrounding lakes. Significant biological changes have accompanied the chemical improvements. Evidence of relatively rapid recovery was found for benthic filamentous algae, phytoplankton, zooplankton, mobile species of benthic invertebrates, and some fish populations. Organisms with low dispersal ability (e.g. Hyalella azteca) have not yet recolonized these lakes. The partial recovery observed to date shows movement toward re-establishment of biological communities typical of natural Precambrian Shield lakes in this area. These findings offer strong support for further efforts to reduce industrial emissions of pollutants to the atmosphere.     

Age- and sex-based comparative distribution of selected metals in the scalp hair of an urban population from two cities in Pakistan

Concentrations of Cu, Zn, Pb and Ni in the scalp hair of male and female donors, with an age range of 6-60 years, were determined by ICP atomic emission spectroscopy. The donors were drawn from the densely populated city of Lahore and the relatively less-populated capital city of Islamabad for comparative evaluation of the metal levels in relation to age, sex and location. Linear regression analyses and correlation between paired metals indicated a positive correlation between Cu and Zn for both sexes ( [Formula: see text] ) and between Pb and Ni ( [Formula: see text] ) for males and females of Lahore. Metal concentrations varied between the two cities and the two sexes. The highest mean concentration was found for Zn at 180.5 microg g(-1) for males and 202.4 microg g(-1) for females from Lahore, while for counterparts from Islamabad the values were 105.2 microg g(-1) and 206.6 microg g(-1). Copper showed an identical mean concentration (20.8 microg g(-1)) in the hair of both males and females from Lahore; however, relatively lower mean concentrations (7.7 and 10.8 microg g(-1)) were observed for donors from Islamabad. Mean Pb concentrations in hair of male donors from Lahore and Islamabad were 9.4 and 7.0 microg g(-1), respectively; in female groups the concentrations were 14.3 and 5.7 microg g(-1), respectively. Ni showed the lowest concentration range (4.3-4.5 microg g(-1)) of all the four metals for subjects from Lahore, and this was higher than the corresponding range (2.0-3.2 microg g(-1)) for subjects from Islamabad. The findings are discussed in relation to the available data from the literature.     

碰撞带岩浆作用的地球化学特征

<正> 在本文中我们特别细致地探讨了碰撞岩浆作用的构造环境与地球化学之间的关系。首先,我们介绍了关于碰撞侵入岩资料的来源和如何根据侵入岩在碰撞带中的时空背景将这些资料划分为4组。然后,我们将这些组的成分进行对比,以便确定形成岩浆的源区在碰撞事件过程中的可能变化。     

格陵兰出产的一种新宝石材料——虹彩正闪石

虹彩正闪石是格陵兰正在开发的一种新宝石材料。本文对该宝石材料的发现过程、产状、物理和化学性质及其化学成分。宝石学性质、切割琢磨技术性能,以及其商品化前景,都作了较全面的介绍和预测。虹彩正闪石宝石材料的发现和开发,无疑为寻找新宝石材料提供了有益的线索。