Contamination of superficial sediments by heavy metals and iron in the Bizerte lagoon,northern Tunisia     

Amor Ben Garali  Mohamed Ouakad  Moncef Gueddari 《Arabian Journal of Geosciences》2010,3(3):295-306

According to the norms adopted by the National Network of observation of the marine life quality (RNO 1997) and US National Oceanic and Atmospheric Administration (US NOAA 1999), the superficial sediments of the Bizerte lagoon (northern Tunisia) show a contamination by nickel, which is the probable consequence of the closeness to the industrial zone, and by lead, the result of detrital material rich in lead of the geological lands of Jbel Kchabta and Jbel Messeftine. In the lagoon southern and eastern sectors, the contamination of superficial sediments is essentially by copper, zinc, nickel and iron. This pollution is related, on one hand, to the rejections of the steelworks El Fouledh and the military arsenal, and on the other hand, to Menzel Bourguiba waste disposal. The rest of the lagoon is exempted from any metallic contamination of the surface sediments. The enriched zones in manganese and zinc correspond to the higher contents in kaolinite and in smectite. Positive correlations were recorded between the percentage in fine fraction on the one hand, and the sedimentary contents in TOC, total nitrogen and heavy metals on the other hand. The majority of the analysed elements are “argilophilous” except zinc and manganese, which are clayey organophile. These results show that this lagoon receives concentrations in anthropogenic metals that risk provoking more or less important disruptions, which are harmful and irreversible on the fauna and flora of this lagoon and on the whole ecobiological equilibrium.  相似文献   

Amateur decision-making in avalanche terrain with and without a decision aid: a stated choice survey     

Pascal Haegeli  Wolfgang Haider  Margo Longland  Ben Beardmore 《Natural Hazards》2010,52(1):185-209

Avalanches pose a serious threat to recreational backcountry travelers in mountainous terrain. This study explores how the three main amateur user groups of avalanche terrain in western Canada (backcountry skiers, out-of-bound skiers, and snowmobile riders) balance recreational goals with safety concerns when choosing backcountry destinations under varying avalanche conditions. Using a discrete choice experiment (DCE), a stated preference technique, the study first examines the strengths and weaknesses in the decision process of the three amateur groups by comparing their responses with the choice patterns of professional mountain guides. The results show that the decision-making strategies employed by the respective amateur groups vary considerably in their level of complexity and the degree to which avalanche safety considerations are incorporated. Second, we examine the effects of a decision aid that preprocesses the most crucial pieces of avalanche hazard information on the decision preferences of the amateur groups in the DCE. The results show that a relatively simple decision aid can influence the decision-making process considerably and steer users towards more avalanche hazard sensitive behaviour.  相似文献   

褐点石斑鱼不同组织4种同工酶的研究   总被引：5，自引：0，他引：5  

尹绍武  廖经球  黄海  雷从改  陈国华  张本 《海洋通报》2007,26(1):41-44

运用聚丙烯酰胺垂直梯度凝胶电泳法对褐点石斑鱼7种组织(眼睛、肌肉、心脏、肝脏、肾脏、尾鳍、脾脏)的4种同工酶(EST、SOD、LDH、MDH)进行了初步研究。结果表明:褐点石斑鱼的4种同工酶系统具有不同程度的组织特异性。EST由4个基因位点编码,具有多态性现象;肌肉SOD与其它组织SOD有明显差异;眼睛LDH酶谱酶带最多;MDH具有线粒体型(m-MDH)和上清液型(s-MDH)两种类型。  相似文献   

盐生植物萌发期对盐胁迫的适应研究进展          下载免费PDF全文

胡娟  张洁  盛洲  周宸宇  张旭萍  拉本 《盐湖研究》2022,30(1):95-100

目前我国盐渍土地面积较大,尤其是青藏高原的盐渍地,常伴有干旱、半干旱的生境,导致植物不易生长,生态环境相对恶劣,这种生态现状亟待解决。盐生植物具有一定的耐盐性和耐旱性,是改善盐渍地的首选植物,种子的活力决定了种子萌发的情况,多数学者为改善严峻的生态环境开始了盐生植物引种的研究。测定种子活力有直接方法和间接方法,大多数学者采用的是直接方法,即在实验室模拟一定条件直接测定萌发率。简述了盐生植物的概况、制造胁迫的主要方法以及检测种子活力的指标,综述了近年来不同学者对盐爪爪、白刺等具有代表性的22种盐生植物在种子萌发期的耐盐性以及抗旱性的相关研究,为改善盐渍地的生态环境、提升盐渍地的生产量提供了理论基础。  相似文献