川西南上震旦统灯影组的研究取得重要进展

最近我们在川西南的甘洛凉红,汉源桂贤等地对上震旦统灯影组的研究中,有一些重要发现,现择要报道,以期引起地质界同仁的注意。 一、在灯影组内特别是灯影组第二段,即过去所称的“富藻段”内发现大量的古陆上暴露带的标志,其中计有渗流豆石、渣状层或渣状白云岩、白云石化淡水方解石、帐蓬构造等,过去将其分别定为核形石、砾屑白云岩、花斑状白云岩、卷发状白云岩等。     

银基汞膜电极活化法

广泛应用于极谱分析的银基汞膜电极,具有高灵敏度、方便、快速等优点;然而,却难以掌握其重现性及稳定性;如何使汞膜电极灵敏度、重现性和稳定性规范化,便成为急需解决的问题。作者提出“电极活化法”,能使汞膜电极在数分钟内达到高灵敏状态,并使其获得良好的重现性及稳定性。     

海洋油污染源的鉴定

近几十年来,随着工业的迅速发展,尤其是石油开发、石油运输,以及其他石油工业的发展,海洋污染日趋严重。因此,检测海洋的油污染问题,引起了世界各国的普遍重视。特别是海滨、海湾及近海石油污染源的鉴别,对海域的环境保护具有十分重要的意义。目前鉴定油污染源的指标和方法,各不相同。有红外吸收光谱法,钒镍比值、硫的百分比,紫外吸收法,萤光光度法,内部反射光谱法,气相色谱法,薄层色谱法,以及其他物理化学法,如相对密度、粘度、皂化值等。物理化学法,如粘度、密度等受油性质改变而改变,尤其是油样在海水中长期漂浮后,     

Effect of dietary supplementation of vitamin C on growth,reactive oxygen species,and antioxidant enzyme activity of Apostichopus japonicus (Selenka) juveniles exposed to nitrite

Different amounts of vitamin C were added to diets fed to juveniles(2.5 ± 0.15 g) of sea cucumber Apostichopus japonic u s(Selenka) in an attempt to reduce the stress response of specimens exposed to nitrite stress. A commercial feed was used as the control diet and three experimental diets were made by supplementing 1 000, 1 500, or 2 000 mg vitamin C/kg diet to control diet separately in a 45-day experiment. Sea cucumbers were exposed to three different levels(0.5, 1.0, and 1.5 mg/L) of nitrite stress for 4, 8, and 12 h at four time intervals(0, 15, 30, and 45 d). Growth of the animals was recorded during the experiment. Reactive oxygen species(ROS)(i.e. hydroxyl free radical(-OH), malondialdehyde(MDA) and total antioxidant capacity(T-AOC)) and antioxidant enzyme activities(i.e., superoxide dismutase(SOD) and catalase(CAT)) were measured. Response surface methodology(RSM) was used to analyze the effect of multiple factors on ROS indices and enzyme activities. Weight gain(WG) and special growth rate(SGR) of vitamin C supplementation groups were significantly higher than those of control group( P 0.05). The levels of-OH and MDA increased under exposure time extending and nitrite concentration increasing, whereas T-AOC level decreased. SOD and CAT activities increased at 4 h and 8 h and decreased at 12 h. During the days in which the animal consumed experimental diets, the levels of-OH and MDA decreased and that of T-AOC increased. This result suggests that diets containing vitamin C could reduce the nitrite stress response in the animals and increase their antioxidant capacity. The multifactor regression equation of growth performance, ROS indices, and duration of feeding results suggest that vitamin C supplementation of 1 400–2 000 mg/kg diet for 29–35 days could reduce effectively the effects of nitrite exposure.