用大型底栖动物和ODP系统评价珠江的有机污染

采用大型底栖动物需氧有机体百分率ODP(oxygen demander percentage)法对广州珠江前航道、西航道和流溪河的下游段进行河流有机污染评价.结果显示:底栖动物需氧类群密度在三河段间分布确有显著性差异,并根据其ODP可以判断流溪河水质相对较好,水质级别为中国地表水环境质量标准(EQSSW)Ⅳ级,西航道和前航道水质级别都为Ⅴ级.通过测试,这一方法能成功地应用在珠江及流溪河,且该法可以较好地匹配于EQSSW五级评价系统,初步认为ODP系统可以成为一个较好的河流水质生物监测方法.图3表4参13     

Phytoremediation of Atrazine by Poplar Trees: Toxicity,Uptake, and Transformation

Toxicity, uptake, and transformation of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] by three species of poplar tree were assessed. Poplar cuttings were grown in sealed flasks with hydrophonic solutions and exposed to various concentrations of atrazine for a period of two weeks. Toxicity effects were evaluated by monitoring transpiration and measuring poplar cutting mass. Exposure to higher atrazine concentrations resulted in decrease of biomass and transpiration accompanied by leaf chlorosis and abscission. However, poplar cuttings exposed to lower concentrations of atrazine grew well and transpired at a constant rate during experiment periods. Poplar cuttings could take up, hydrolyze, and dealkylate atrazine to less toxic metabolites. Metabolism of atrazine occurred in roots, stems, and leaves and became more complete with increased residence time in tissue. These results suggest that phytoremediation is a viable approach to removing atrazine from contaminated water and should be considered for other contaminants.     

The hazard of forest fires in southern France

The annual hazard of fire in the forest, maquis and garrigue of southern France is related both to the fragile nature of the Mediterranean ecosystem and to man's activities. The Mediterranean vegetation is adapted to withstand the aridity of the summer months, but the combination of high temperatures, low precipitation, critical soil-moisture levels and occasional bouts of strong winds (mistral) desiccate the vegetation cover and create conditions in which outbreaks of forest fires are inevitable. Although the annual incidence and impact of forest fires are related to the occurrence of extreme weather conditions they are also exacerbated by depopulation of the remoter rural areas, the spread of urbanization and the growth of tourist facilities in the more accessible coastal zones, and above dl by man's carelessness. This article reviews the factors affecting the nature and severity of forest fires and discusses the attempts being made to prevent and control forest fires in the Mediterranean zone of southern France     

Natural Hazard Reporting in the UK Press

Important sources of information concerning world natural hazards are provided by the mass media, especially newspapers. The nature, depth and consistency of the reporting, however, varies considerably depending upon the journalistic approach of the newspaper and on the perceived 'newsworthiness' of a disaster. Intensive events are much more likely to receive attention than pervasive hazards but other contributory factors play a part, such as the day, time, severity in terms of damage and loss of life, and location of the event. This paper reflects on the reporting of natural hazards in UK newspapers and is based on an analysis of press cuttings taken over a period of twelve months. The survey indicated that there is a very uneven coverage of world disasters, that location maps are scarce, and that valuable follow-up reporting is minimal.