Fingerprinting TCE in a bedrock aquifer using compound-specific isotope analysis

A dual isotope approach based on compound-specific isotope analysis (CSIA) of carbon (C) and chlorine (Cl) was used to identify sources of persistent trichloroethylene (TCE) that caused the shut-down in 1994 of a municipal well in an extensive fractured dolostone aquifer beneath Guelph, Ontario. Several nearby industrial properties have known subsurface TCE contamination; however, only one has created a comprehensive monitoring network in the bedrock. The impacted municipal well and many monitoring wells were sampled for volatile organic compounds (VOCs), inorganic parameters, and CSIA. A wide range in isotope values was observed at the study site. The TCE varies between -35.6‰ and -21.8‰ and from 1.6‰ to 3.2‰ for δ(13) C and δ(37) Cl, respectively. In case of cis-1,2-dichloroethene, the isotope values range between -36.3‰ and -18.9‰ and from 2.4‰ to 4.7‰ for δ(13) C and δ(37) Cl, respectively. The dual isotope approach represented by a plot of δ(13) C vs. δ(37) Cl shows the municipal well samples grouped in a domain clearly separate from all other samples from the property with the comprehensive well network. The CSIA results collected under non-pumping and short-term pumping conditions thus indicate that this particular property, which has been studied intensively for several years, is not a substantial contributor of the TCE presently in the municipal well under non-pumping conditions. This case study demonstrates that CSIA signatures would have been useful much earlier in the quest to examine sources of the TCE in the municipal well if bedrock monitoring wells had been located at several depths beneath each of the potential TCE-contributing properties. Moreover, the CSIA results show that microbial reductive dechlorination of TCE occurs in some parts of the bedrock aquifer. At this site, the use of CSIA for C and Cl in combination with analyses of VOC and redox parameters proved to be important due to the complexity introduced by biodegradation in the complex fractured rock aquifer. It is highly recommended to revisit the study when the municipal well is back into full operation.     

Assessment of urban and industrial contamination levels in the bay of Cádiz,SW Spain

Measuring the amount of pollution is of particular importance in assessing the quality and general condition of an ecosystem. In this paper, some of the results obtained as a consequence of the specific agreement between the Environmental Agency (Consejería de Medio Ambiente, Junta de Andalucía) and the University of Cadiz to assess the environmental condition of the marine bottom and waters are showed. Physical and chemical analyses in water and sediments were undertaken at various sampling sites close to urban and industrial locations. Later on, these results were studied under statistical analysis to reveal any possible relationships between the parameters employed, and to identify any analogous behaviour between the sampling sites. Physical-chemical data revealed that sediments and waters analysed were moderately contaminated and, in addition, no great differences were found between in rising and ebbing tide conditions. Finally, considering only the pollution level, from the cluster analysis of sediments two major groups appear, one of which corresponded to those sites located in the outer bay, and the other to those situated in the inner bay. However, number 6 and 14 sampling sites cannot be associated to those groups due to be related to points with important local discharges.     

滇东南及邻区晚古生代─中生代沉积盆地演化及微细粒型金矿成矿作用分析

通过对滇东南及邻区晚古生代至中生代沉积盆地演化的研究，及滇黔桂交界处的“金三角”地区微细粒型金矿的空间分布规律、产出层位、区域成矿地质条件，以及成矿作用的综合分析，笔者认为：该区微细粒型金矿的金源自地壳深部，其成矿与该区晚古生代以来的地幔上隆拉伸及扩容拉伸作用和多期岩浆活动有关，并形成以右江地幔隆起为中心的微细粒型金矿成矿带。该矿带具有自幔隆中心向外矿化渐弱、矿床规模变小、赋矿层位变老等规律。     

The delivery of family planning services in Egypt with particular reference to population policy and health care planning

Egypt's general population growth since 1805 is reviewed, with particular reference to the effect of changes in fertility and mortality since 1906 and factors affecting these variables. The rapidity of mortality decline is stressed and the nature of the epidemiological transition considered. In the light of population projections Egypt's population policies are described, and the diffusion of family planning since 1965 particularly is examined on a governorate basis. Finally, the success of the Population and Development Project set up in 1977 in instituting a radically new approach to family planning is presented.