化学教学中的环境教育

环境教育是国家环保工作和教育事业的重要组成部分。本文从化学教学的角度出发 ,探讨了在中学开展环境教育的理论、途径、方法     

The ion chemistry of surface and ground waters in the Taklimakan Desert of Tarim Basin, western China

The physio-chemical and chemical features of water in natural conditions are controlled by the weath-ering of bedrocks,local climate,landforms and other geo-environmental parameters. In order to un-derstand the characteristics of water and the origins of the dissolved loads in the rivers and in the ground waters of the Taklimakan Desert,western China,we studied the ions in the water samples col-lected from rivers and wells. We collected water samples from four rivers (Keriya River,Cele River,Tumiya River and Yulongkashi River) in the southern desert and ground water samples from many parts of the desert. Major cations and anions were measured using ion-chromatograph and titration with HCl. The total dissolved solids (TDS),pH and conductivity were examined on site by a portable multi-parameter analyzer. The data show that the water in the rivers of southern Taklimakan is still of fresh water quality and slight alkalinity,although the TDS is comparatively higher than that of many other rivers of the world. The ground water is fresh to slightly saline,with TDS a little higher than that of river water in the study area. The concentration of ions is slightly different between the four rivers in the southern Taklimakan. However,the chemistries of ground water in all samples are to a large degree controlled by sodium and chloride. The ions in the ground water are concluded to be mainly from dissolving of evaporites,consistent with the dry climate in the region,whereas the ions in the rivers are mainly from rock weathering. Low-level human imprints are recognized in the ground water samples also.     

Pigment chemistry: the red sweat of the hippopotamus

Within a few minutes of perspiration, the colourless, viscous sweat of the hippopotamus gradually turns red, and then brown as the pigment polymerizes. Here we isolate and characterize the pigments responsible for this colour reaction. The unstable red and orange pigments turn out to be non-benzenoid aromatic compounds that are unexpectedly acidic and have antibiotic as well as sunscreen activity.