地球的全球演化:可能模型

地球的前半部历史可明显地分为以下几个阶段:(1)4.6～4.5Ga,地球形成,其表面具“岩浆海洋”;(2)4.5～4.2Ga,原始地壳和软流圈形成地壳受到强烈压实作用,大规模火山活动,原始大气圈中突发性地出现大气圈和水圈,地幔中出现不规则对流;(3)4.2～3.9Ga,上地幔受到来自行星内部深处的热作用引起大规模科马提岩火山作用,岩石圈被一层厚科马提岩覆盖并变得比熔融状态的软流圈更为致密。这种重力不稳定性导致了雏形     

热液交代带形成的流体动力学模式

从吸收的角度对流体物质与能使其蒸气透过的岩石(通道壁)之间的质量交换动力学进行了研究。如在角砾岩带物质的行为是由溶液与通道壁以及所充填的固体颗粒(吸收剂)决定的。物质的吸收和非吸收也是由环境与流体流过的通道之间的温度与压力梯度决定的。在准平衡情况下,当密度缓慢变化以及吸收和非吸收系数分别很高时,就能得到盐平衡的方程式。这一方程描述了在时间t时×点瞬时浓度的变化。在上述情况下当吸收速     

多参量求索救援图像的地质解译

雷达图像被认为是分析地质构造最有效的资料之一,并且在常年植被覆盖严重、甚至在多云气候条件的地区如热带的亚洲国家中都有很好的应用前景。微波的每个频率波段有其特殊的反射特性和粗糙度。同时图像的质量受入射角和俯视方向的影响。这就是说在所有情况下应根据工作区的工作目的选择最合适的图像。从这些观点来看,多参量求索援救图像是适合干地质解译的。     

南极冰岩芯的证据说明最近积雪量增加

目前,对南极冰盖物质平衡的了解有许多不确定因素,这是因为缺少外流冰和雪积累速率两方面的资料。根据目前资料估计,外流冰量和雪的净积累量大致相等,约为每年2000 km~3冰(相当于6毫米海平面)。冰雪积累速率的短期变化是确定物质平衡的关键问题,因为随着气候的短时变化,冰雪积累可发生急剧变化,而冰流的变化只能在较长的时间尺度上反映出来。这里我们给出的是1806年以来沿东南极一个长700公里地段的净积雪速率的时序变化。冰雪积累记录是根据冰岩芯中年层的厚度,并且以氧同位素比值的季节变化和冰壳层理的季节变化换算的。我们发现在1960年前后,冰雪积累速率达最小值之后曾经有一次明显增加,导致近期的积累速率超过了长期平均值,达到20%。如果这种近期的增加是广泛分布的,正如南极大部分地区短期积累资料所表示的那样,那么这种正向不平衡(物质输入达5—25%)可能只出现在60年代末期以后。     

银(Ⅰ)和碘离子的分光光度微量测定

<正> 本文报导在银(Ⅰ)的分光光度测定中的一种灵敏显色剂,一种新的杂环偶氮染料——4—(2—喹啉偶氮)苯(P—QAP)的分析功能。银(Ⅰ)—(P—QAP)络合物也已用于碘离子的微量测定。所依据的原理是,配位体的交换反应和加入碘离子前后银(Ⅰ)—(P—QAP)络合物吸光度与试剂空白吸光度之差与碘离于浓度成正比。方法既快又简便,并且与已发表的一些其它方法相比,其精确性是高的。     

Esterase activities in the bivalve mollusc Adamussium colbecki as a biomarker for pollution monitoring in the Antarctic marine environment

Marine environments are continuously being threatened by a large number of xenobiotics from anthropogenic sources. Even in sparsely populated and relatively pristine areas, such as Antarctica, hazardous chemicals can pose a serious environmental problem. The main aims of the present study were to (1) validate and optimize an analytical technique utilizing a microtitre-plate photometer to ascertain background levels of esterase activities in the Antarctic bivalve Adamussium colbecki, (2) carry out in situ monitoring of esterase activities to assess any potential environmental impacts of the Italian Scientific Antarctic Base "Terra Nova Bay" on the surrounding marine area. Results showed the presence of organophosphorous-sensitive cholinesterase (ChE) and carboxylesterase (CbE) activities in the gills of A. colbecki and optimal assay conditions were comparable with those found for bivalve species from temperate areas. A higher sensitivity of ChE versus acetylthiocholine activity in A. colbecki to chlorpyrifos compared to species from temperate areas may also be inferred. The in situ study indicated no differences in the environmental quality of the three study sites located around the Italian Base.     

Effects of pollution on zooplankton abundance and distribution in two estuaries of the Basque coast (Bay of Biscay)

The abundance and spatial distribution of mesozooplankton were compared in the euhaline region of the polluted Bilbao estuary and the unperturbed Urdaibai estuary. The environmental variables measured were salinity, temperature, dissolved oxygen saturation, chlorophyll a, particulate organic matter and Secchi disk depth. Differences in the environmental variables and zooplankton between the estuaries and within the estuaries were tested statistically. Differences in the patterns of mesozooplankton abundance with salinity in each estuary indicated that they were affected by pollution in the Bilbao. Total mesozooplankton, and several mesozooplankton categories were more abundant in the Bilbao at higher salinities but in the Urdaibai at lower salinities. Therefore, we deduced that, in the Bilbao, zooplankton abundance was enhanced by the moderate pollution at the outer euhaline zone and limited by the poorer conditions of the inner zone. The response of the various zooplankton categories to the pollution is discussed.