Cell bioassays for detection of aryl hydrocarbon (AhR) and estrogen receptor (ER) mediated activity in environmental samples

In vitro cell bioassays are useful techniques for the determination of receptor-mediated activities in environmental samples containing complex mixtures of contaminants. The cell bioassays determine contamination by pollutants that act through specific modes of action. This article presents strategies for the evaluation of aryl hydrocarbon receptor (hereafter referred as dioxin-like) or estrogen receptor mediated activities of potential endocrine disrupting compounds in complex environmental mixtures. Extracts from various types of environmental or food matrices can be tested by this technique to evaluate their 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents or estrogenic equivalents and to identify contaminated samples that need further investigation using resource-intensive instrumental analyses. Fractionation of sample extracts exhibiting significant activities, and subsequent reanalysis with the bioassays can identify important classes of contaminants that are responsible for the observed activity. Effect-directed chemical analysis is performed only for the active fractions to determine the responsible compounds. Potency-balance estimates of all major compounds contributing to the observed effects can be calculated to determine if all of the activity has been identified, and to assess the potential for interactions such as synergism or antagonism among contaminants present in the complex mixtures. The bioassay approach is an efficient (fast and cost effective) screening system to identify the samples of interest and to provide basic information for further analysis and risk evaluation.     

The distribution characteristics of bacterial beta-glucosidase activity in Taiwan strait

Twenty stations were established in the near-shore regions of South Fujian Shoal (116°10′–119°00^′ E, 21°20′–24°10′ N) on summer and winter cruises during the period from August 1997 and February to March 1998. The distribution pattern of marine bacterial β-glucosidase activity (β-GlcA) has been investigated by using fluorogenic model substrate (FMS) technique in order to have better understanding of the β-GlcA, as well as its relation to marine bacterial biomass, productivity and environmental factors in Taiwan strait. The results showed that: (1) In summer, the average of β-GlcA at the Southern stations of Taiwan strait was 1.94 nmol/1 h. While in winter, the average of β-GlcA at the Northern stations was 0.86 nmol/1 h and the range of variation (0.34–1.89 nmol/1 h) was much more narrow than that in summer (0.31–8.1 nmol/1 h). (2) According to the carbon conversion factor, the β-GlcA was 0.14 and 0.062 ugc/1 h in summer and winter respectively. These β-GlcA values were higher than the bacterial production of the two seasons respectively. (3) The β-GlcA gradually rises from offshore water to near-shore water. (4) The correlation between the β-GlcA and the bacterial secondary production was not so obvious. (5) The correlation between the section distributions, daily varying of the β-GlcA and the bacterial production was not obvious. (6) In the surface water, the distribution character of free-state β-GlcA from bacteria was equal to that of the total β-GlcA in the whole sea area.     

Aquaculture-related trace metals in sediments and lobsters and relevance to environmental monitoring program ratings for near-field effects

The study was undertaken to assess the marine environmental effects from feed and waste associated with aquaculture activities. Metal compositions of sediment, lobster, and feed were used to evaluate the extent of detectable effects at 0 m (under the cage) and 50 m distance. Sediments that were collected under the cages and were characterised as hypoxic or anoxic, showed elevated levels of Cu, Zn, organic carbon, and % <63 microm particles, and low Mn and Fe. At 50 m there was a major reduction in waste chemical impact. Using lobster, a bioindicator species, as a tool for detecting near-field impacts, showed accumulations of high Cu associated with active aquaculture sites. Chemical compositions and metal ratios normalised with organic carbon, were used to assess the sediment conditions associated with environmental monitoring program ratings (EMP--normal, hypoxic, and anoxic). Principal component analysis (PCA) was used to explore chemical data at all sites for differentiating normal, hypoxic and anoxic sediment conditions. Selected variables (Cu, Zn, Fe, Mn, organic carbon, and particles <63 microm) were sufficient for the PCA approach with >90% explainable variance of first two components. The groupings based on PCA and cluster analysis were similar to EMP classifications with some exceptions of mis-identification by EMP. The sediment chemistry components were valid indicators for evaluating marine environmental conditions and for assessing aquaculture operating sites. The developed techniques, using chemical variables in combination with EMP and the statistical approach should be useful to predict the effects of aquaculture practices and the suitability of aquaculture operations.     

Discovery of the Middle-Late Triassic elasmobranch ichthyoliths from the Guanling area,Guizhou,SW China

应用Johns等(1997)的形态分类系统，对首次报道出现于贵州关岭地区中上三叠统的软骨鱼类的微体化石进行了初步研究，描述了其中的1个牙齿化石(可能属于弓鲛鳖科的)和7个鳞片类化石的形态属种，其中包括两个鳞片类化石的新属种，即Lobaticorona cf. floriditurris,Sacrisubcorona co. circabasis,Glabrisubcarona co.arduidevexa,Parvi-corona dacrysulca n.gen.et.n.sp.s.f.Annulicorona pyramidalis n.gen.et.n.sp.s.f.,new(?) paragenera A和new(?) paragenera B。还初步探讨了软骨鱼类微体化石在三叠纪地层划分中的应用，以及中国西南部三叠纪软骨鱼类与北美相当地层中软骨鱼类的洲际对比。     

统一的地震定标律

发生在加利福尼亚的地震之间的等待时间分布遵从简单的统一定标律。这一定标律的有效范围从数十秒到数十年。短期丛集，也就是通常所说的余震，只是地震一般层级性质的短期限定。没有唯一的区分主震和余震的操作方法。在该统一定标律中，古登堡一里克特b值、余震大森定律的指数-1和地震的分维数df表现为关键指数。     

由S波分裂随时间变化导出的断层快速愈合的证据

Tadokoro等(1999)曾对野岛断层带1995年兵库县南部地震后9～12个月期间的地震做了s波分裂分析。其快速剪切波偏振方向Ψ始终与断层走向平行，这表明剪切断层是破裂的起因。在该项研究中，我们另外做了主震后33～45个月的S波分裂分析并检测到了Ψ的旋转，其结果是Ψ平行于和断层走向斜交的区域最大水平压应力方向。这一剪切波偏振方向随时间的变化表明，在上述两个时段之间由剪切断层引起的破裂完全愈合，而构造应力引起的裂纹也得以恢复。在主震后33个月内所完成的这一变化过程，是断层快速愈合的强有力的证据。     

磁暴期间极光椭圆与极盖区电离层效应比较研究——F区负暴

联合利用EISCAT和E-Svalbard非相干散射雷达数据,研究l997年5月强磁暴期间向阳侧极盖与极光椭圆区电离层F区负暴.发现在磁暴主相和恢复相初期,极光椭圆和极盖区电离层都在大约l90km高度出现类似F1的峰,F2主峰完全消失,F区电子密度大幅度下降.但离子温度的变化在两个区域很不相同,在极光椭圆区大幅度升高,而在极盖区没有显著变化,反映出引起F区负暴的主要机制在两个区域不尽相同.强对流电场引起大气焦耳加热与离子增温而使O+离子消失的化学反应速率增大所导致的电离损失,对极光椭圆区负暴起主要作用;而输运过程,特别是持续长达数小时的沿场上行离子流,对极盖区负暴起重要作用.磁暴主相期间,当EISCAT雷达位于等离子体对流涡旋转换区下方时,在无焦耳加热与离子摩擦增温的情况下,观测到由顶部电离层O+离子沿场高速外流引起的F区电子密度耗空.     

青藏高原季风期降水的日变化

利用1998年夏季GAME－TIBET IOT期间的探空、降水和雷达资料分析了季风期降水和CAPE、LCL热力参量的日变化及其之间的关系。降水的日变化很明显，最大的降水和CAPE的最大值出现在同一时间段。6km和8.5km高度内的大气层结在大部分时间是不稳定的。0400－0800时间内6km以下9km以上的稳定层结阻碍了对流系统的发展，降水的日变化与这些热力参数的日变化有关。同时，利用三维云模式模拟了降水的日变化和水汽及温度对降水的影响，云模式再现了降水和回波强度的最大和最小值，晚上低层的高湿度是影响降水的重要因素。