Different cardiac response to copper in limpets from metal polluted and clean shores of Hong Kong     

Chelazzi G  De Pirro M  Williams GA 《Marine environmental research》2004,58(1):83-93

The gastropod limpet, Cellana grata, is common on moderately exposed to exposed Hong Kong rocky shores. On the basis of the existing literature on trace metal contamination in Hong Kong, four sites were identified, representative of highly polluted (Aberdeen and Lei Yue Mun) and clean (Cape d'Aguilar and Clear Water Bay) conditions. Limpets from the two polluted sites showed similar, but significantly higher body concentrations of copper than limpets from the two clean sites, which were also similar. Non-invasive measurements of cardiac activity of limpets from the four sites showed between site differences in baseline heart rates under standard seawater, irrespective of pollution level. When acutely exposed to water borne copper (2 h, 0.5+/-0.06 SD ppm), however, limpets from clean sites showed a significantly higher increase in inter-beating time (bradycardia) than those from polluted sites. These results highlight the potential use of cardiac activity to assess the exposure of natural populations of limpets to trace metal pollution.  相似文献   

Demographic transition in Sri Lanka: a spatial perspective   总被引：1，自引：0，他引：1  

Fuller GA 《Population geography : a journal of the Association of Population Geographers of India》1984,6(1-2):1-11

Demographic transition theory involves a lagging fertility transition induced by a leading mortality transition. This article focuses on the linkage between the mortality and fertility transitions in Sri Lanka; it discusses the measurement of areal fertility, demonstrates the use of a measure not commonly used in population geography, and shows areal association between past mortality and recent fertility. The Coale or Princeton fertility indices allow a reasonably good view of structural and behavioral aspects of fertility; the Coale indices examine the contribution of structure to total fertility and the contribution of marital fertility. Although recent fertility decline has been less rapid than the post-war mortality decline, Sri Lanka's crude birth rate in 1975 was the 5th lowest in Asia. Sri Lanka experienced very high crude death rates in 1930, and quite low rates in 1950 and in subsequent years. This demonstrates an association between historic mortality and recent fertility, and that association can be linked deductively to demographic transition theory. In 1930, malaria was endemic throughout the Dry Zone of Sri Lanka, and hyperendemic in several districts. The Spearman rank correlation coefficients reveal the strongest relationship between malaria and nuptiality; this lends evidence to the notion that structural influences on fertility--such as delayed marriage--are more important than influences on marital fertility--such as coital frequency. The evidence suggests that mortalily decline in Sri Lanka led to an increase in fertility in those areas where malaria had been concentrated. This suggests the possibility that measures constituting malaria control or eradication also stimulate increased fertility; therefore, anti-malarial programs must be integrated with family planning.  相似文献   

对燕山辽西地区构造格局的认识和讨论     

林晓辉  秦正永 《化工矿产地质》2003,25(1):5-12

燕山辽西地区的盖层可分两个构造层,由燕辽复向斜和秦皇岛背形相互叠加,并相应发育两期推覆构造。复向斜范围包括内蒙地轴和燕山沉降带,是由长条形的三个背斜和二个向斜相间,及配套的EW向纵断裂、SN向横断裂和NE向、NW向的共轭断裂组成。著名的尚义-宽城-凌源-朝阳-北票断裂是复向斜及其次级背斜的轴部纵断裂,以南大岭组、窑坡组和北票组作为其裂隙充填物。燕山EW向断裂南北对冲现象是复向斜纵断裂放射状排列并向核部推覆的反映。复向斜的形成机制完全符合纵弯褶皱作用下岩石的变形原理,是西伯利亚板块和华北板块碰撞的结果;秦皇岛背形的形成是后期太平洋板块俯冲在欧亚板块之下所致。  相似文献   

3年独立研究观测到的地震有关的地电变化     

Tsel.  GA 卢军 《世界地震译丛》1997,(3):9-13

给出了某些地震前地电的观测结果。数据是在帕特雷大学地震中心用ＶＡＮ方法在３年独立实验研究期间搜集的。记录的信号包括：（ａ）地电场的缓慢变化；（ｂ）地电场的周期变化；（ｃ）地震电信号。  相似文献   

双壁钻具用的封隔器     

Ford.  GA 赵杰伟 《国外地质勘探技术》1990,(8):12-13,34

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加拿大安大略赫姆洛帕格-威廉斯金矿的地层、断裂和金矿的关系     

R. I. Valliant  C. J. Bradbrook  林晓辉 《华北地质》1989,(1)

导论金矿出现在加拿大地盾的许多绿岩带中,具有多种地质环境并可被划分成许多矿床类型,包括最近在赫姆洛发现的类型。研究者对金矿的生成是受地层和构造控制已开展争论。赫姆洛的威廉斯矿区的帕格-威廉斯金矿包括A、B、C三带。三个地貌上各异的金矿,均赋存在独特的断层控制的地层层序中,其规模、岩石、构造、丰度、含金的  相似文献   

城市地区灾害评价和沉积学模式的应用     

M‘Kr.  GA  王伍云 《国外第四纪地质》1989,(3):14-24

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井筒施工条件预测方法     

Ferg  GA 赵蔼廉 《国外煤田地质》1989,(5):37-41

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巴布亚新几内亚的波格拉金矿床     

Hand.  GA  林晓辉 《前寒武纪研究进展》1989,(1):53-60

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加拿大安大略州阿比提比绿岩带地质发展中金矿层形成的位置     

林晓辉 《华北地质》1988,(1)

安大略阿比提比(Abitibi)绿岩带火山岩的均匀(除花岗质岩石附近外)低级变质作用和巨大地层视厚度(～40公里),被解释是铲状正断裂的结果。紧接着断裂之后发生从拉斑质到钙碱质最后到钙碱性科马提质的火山旋回。地壳的断裂发生在花岗质岩石侵位的初期,在张应力作用下形成。这类花岗质岩基与钙碱性火山岩同源。在火山喷  相似文献