Sea-level rise impacts on Africa and the effects of mitigation and adaptation: an application of DIVA

This paper assesses sea-level rise impacts on Africa at continental and national scales including the benefits of mitigation and of applying adaptation measures, considering four scenarios of global mean sea-level rises from 64 to 126 cm in the period of 1995–2100. We find that in 2100, 16–27 million people are expected to be flooded per year, and annual damage costs range between US5 and US 5 and US 9 billion, if no adaptation takes place. Mitigation reduces impacts by 11–36%. Adaptation in the form of building dikes to protect against coastal flooding and nourishing beaches to protect against coastal erosion reduces the number of people flooded by two orders of magnitude and cuts damage costs in half by 2100. Following such a protection strategy would require substantial investment. First, Africa’s current adaptation deficit with respect to coastal flooding would need to be addressed. DIVA suggests that a capital investment of US300 billion is required to build dikes adapted to the current surge regime and US 300 billion is required to build dikes adapted to the current surge regime and US 3 billion per year for maintenance. In addition, between US2 and US 2 and US 6 billion per year needs to be spent on protecting against future sea-level rise and socio-economic development by 2100. This suggests that protection is not effective from a monetary perspective but may still be desirable when also taking into account the avoided social impact. We conclude that this issue requires further investigation including sub-national scale studies that look at impacts and adaptation in conjunction with the development agenda and consider a wider range of adaptation options and strategies.     

稻田土壤种子库研究进展

土壤种子库是指存在于土壤表面和土壤中全部存活种子的总和。稻田土壤种子库是地上杂草产生的根本来源。我国是一个水稻种植大国,目前关于稻田土壤种子库的研究还不够全面和深入。研究稻田土壤种子库对于防治稻田草害具有重要指导意义,同时也是种子库研究领域的一个重要补充。取样方法和取样时间是研究土壤种子库的关键所在。而萌发法是最常见的判定方法。关于稻田土壤种子库大小的结论相差很大,从103~105 m-2不等。稻田土壤种子库中的杂草主要有19科55种,一般的稻田可检出10科或20种左右。种子的垂直分布格局主要受耕作强度的影响。70%~80%甚至更多的杂草种子分布在0~10 cm。稻田土壤种子库由于萌发、捕食、衰老和种子散布等原因具有季节动态。轮作制度、耕作方式、不同施肥处理以及除草方式等对稻田土壤种子库有重要影响。连续多年的田间管理会使种子库的大小、分布和物种组成产生年际变化。目前,需要加强长期定位研究,扩大研究区域和研究内容,重点研究杂草种子的休眠萌发机制和种子命运研究,为杂草治理提供更准确的信息。     

The Distracting Effects of a Ringing Cell Phone: An Investigation of the Laboratory and the Classroom Setting

The detrimental effects of a ringing phone on cognitive performance were investigated in four experiments. In Experiments 1 and 2, the effects of different types of sounds (a standard cell phone ring, irrelevant tones and an instrumental song commonly encountered by participants) on performance were examined. In Experiment 1, slower responses were observed in all auditory groups relative to a silence condition, but participants in the ring and song conditions recovered more slowly. In Experiment 2, participants who were warned about the potential for distraction recovered more quickly, suggesting a benefit of this prior knowledge. This investigation continued in a college classroom setting (Experiments 3a and 3b); students were exposed to a ringing cell phone during the lecture. Performance on a surprise quiz revealed low accuracy rates on material presented while the phone was ringing. These findings offer insight into top-down cognitive processes that moderate involuntary orienting responses associated with a common stimulus encountered in the environment.     

Perfluorierte Tenside (PFT) in der aquatischen Umwelt und im Trinkwasser

Recent scientific research on perfluorinated surfactants (PS) revealed their ocurrence in German surface and drinking waters (Skutlarek, Exner, Färber 2006). Since several years, PS have been found in the global environment, especially in animal and human tissues. PS possess extreme persistence against microbiological and chemical degradation and are able to bioaccumulate in animals and humans (Houde et al. 2006). PS concentrations (sum of 12 components) in the Rhine river and its main tributaries were determined below 100 ng/L, but the rivers Ruhr (tributary of the Rhine) and Möhne (tributary of the Ruhr) showed remarkable high concentrations (Ruhr: up to 446 ng/L, Möhne: up to 4385 ng/L). The maximum concentration in drinking waters was 598 ng/L with the major component perfluorooctanoic acid (PFOA). The PS concentrations decreased similarly to the PS concentrations of the raw waters along the flow direction of the Ruhr river. Therefore it seems to be necessary to install legal regulations for these compounds.     

A chemox treatment for urea‐ and ammonium‐contaminated groundwater

In a pilot project performed at a fertilizer manufacturing facility, a one‐step chemical oxidation technique successfully treated urea‐ and ammonium‐contaminated groundwater. The oxidation reaction occurred in an 1,100‐gallon batch reactor. The contaminated inflow was buffered by the metered addition of sodium bicarbonate solution and subsequently treated with sodium hypochlorite in an 8:1 weight ratio of Cl₂:N. In an instantaneous reaction, the urea and ammo‐nium‐N were completely oxidized to nitrogen gas that was vented to the atmosphere during mixing. The pH of the reactor discharge was ?6.5. Sodium sulfite was used to reduce residual hypochlorite in the reactor effluent to chloride to provide process water with characteristics suitable for discharge. Oxidation rates were similar with different strengths of hypochlorite; however, a 5 to 6 percent sodium hypochlorite (as Cl₂) solution was the most stable. © 2005 Wiley Periodicals, Inc.