Microbial survival in space shuttle crash

A slow growing, heat resistant bacterium, identified by 16S rRNA gene sequencing as Microbispora sp., was recovered from the wreckage of the ill-fated space shuttle Columbia (STS-107). As this organism survived disintegration of the space craft, heat of reentry, and impact, it supports the possibility of a natural mechanism for the interplanetary spread of life by meteorites.     

Impacts of maintenance dredged material disposal on macrobenthic structure and secondary productivity

The results of a monitoring programme to assess the spatial impacts associated with ongoing dredged material disposal activity at a dispersive, coastal disposal site (southwest UK) are described. Benthic impacts were assessed using benthic community structure and secondary productivity estimates.Analyses of univariate indices (including secondary production) and multivariate community structure revealed differences between stations inside and those outside the disposal site were minimal. Generally, stations within and outside the disposal site were characterised by the same species. Regression models indicated that the variability in biological structure and secondary production was predominantly accounted for by natural variables (e.g., depth, sediment granulometry) with only a small amount of residual variability being due to contaminant variables. Thus, the elevated levels of certain contaminants in the vicinity of the disposal area were not sufficient to result in significant ecological or ecotoxicological changes. We ascribe such findings partly to the dispersive nature of the disposal site.     

Contaminants in cetaceans from UK waters: status as assessed within the Cetacean Strandings Investigation Programme from 1990 to 2008

Since 1990, tissue samples from UK-stranded and -bycaught cetaceans have been available for study of contaminant burdens. These have been used to study spatial and temporal trends in concentrations in UK waters, and to investigate potential associations between contaminants and health status. We describe the current status of cetaceans (primarily harbour porpoises, Phocoena phocoena) in UK waters in relation to pollution. Concentrations of BDEs, HBCD, and the organochlorine pesticides are declining. In contrast, concentrations of CBs have plateaued following earlier reductions due to regulation of use, and further reductions are likely to take decades. Blubber PCB concentrations are still at toxicologically significant levels in many harbour porpoises and regularly occur at even higher levels in bottlenose dolphins and killer whales due to their higher trophic level in marine food chains. Further reductions in PCB inputs into the marine environment are needed to mitigate risk from PCB exposure in these species.     

A comparison of three-dimensional interpolation techniques for plume characterization

Interpolation of contaminant data can present a significant challenge due to sample clustering and sharp gradients in concentration. The research presented in this paper represents a study of commonly used interpolation schemes applied to three-dimensional plume characterization. Kriging, natural neighbor, and inverse distance weighted interpolation were tested on four actual data sets. The accuracy of each scheme was gauged using the cross-validation approach. Each scheme was compared to the other schemes and the effect of various interpolation parameters was studied. The kriging approach resulted in the lowest error at three of the four sites. The simpler and quicker inverse distance weighted approach resulted in a lower interpolation error on the other site and performed well overall. The natural neighbor method had the highest average error at all four sites in spite of the fact that it has been shown to perform well with clustered data. Another unexpected result was that the computationally expensive high order nodal functions resulted in reduced accuracy for the inverse distance weighted and natural neighbor approaches.     

Tl2S—Ag2S假二元系相平衡的实验研究

用抽真空石英管在干体系中对Ａｇ２Ｓ－Ｔｌ２Ｓ假二元系在２５０℃下变温切面相平衡进行了实验研究。Ａｇ２Ｓ－Ｔｌ２Ｓ假二元系在２５０℃存在三个三元合成相，它们分别为ＴｌＡｇＳ、Ａｇ２９Ｔｌ１１Ｓ２０和Ａｇ１７Ｔｌ３Ｓ１０，后两个相是该实验首次合成     

西昌复合盆地层序充填序列与沉积动力演化初探

本从层序地层学和沉积动力学角度，对西昌复合盆地进行了初步的研究。西昌复合盆地在不同地质演化阶段具有不同的大地构造属性，在区域上表现为不同区块具有不同的层序成因格架，显示典型的纵向叠加、横向复合的复式特点。盆地层序充填序列包括2个超层序、5个巨层序、8个一级层序、14个二级层序、76个三级层序以及若干个次一级层序，分别代表2个、5个、8个、14个、76个和若干个相应周期的海(湖)平面变化产物。盆地形成和发展受特提斯洋张力和不同块体边缘聚力的复合控制，其演化经历了褶皱基底固结、被动边缘海盆发展、陆内盆地改造三大阶段，具体包括造山裂谷(Z1)、初始被动边缘(Z2)、稳定被动边缘(∈-P2)、边缘热隆-拉裂(P3)、残余海盆(T1—T2)、周缘前陆(T3-J1)、陆内坳陷(J2-K1)、挤压改造(K2-E1)8个不同时期。     

白云岩化研究的新进展

近年来,随着沉积学理论的发展,白云岩化的研究取得了重大进展,包括白云岩化的物质来源、白云岩化环境、白云岩化阶段和白云岩化机理等。其中以白云岩化机理中与区域构造运动有关的构造热液白云岩化、与火山活动有关的火山热液白云岩化和与变质作用有关的变质热液白云岩化最为重要。