温度骤降对大黄鱼Larimichthys crocea鱼卵与仔鱼的影响          下载免费PDF全文

周孔霖  杜萍  寿鹿  廖一波  刘永叶  黄伟 《海洋学研究》2018,36(4):68-75

滨海电厂温排水停止排放以及季节更替、寒潮来袭等现象会引起海水温度降低,从而对鱼类等变温生物产生冷冲击效应。本研究通过模拟水温骤降情形,以孵化率、死亡率、畸形率等为指标,探讨了温度骤降对大黄鱼早期发育阶段(鱼卵和仔鱼)的冷冲击作用。研究发现,大黄鱼仔鱼(3日龄)对温度骤降的敏感性略高于鱼卵。在大黄鱼鱼卵和仔鱼的适温范围内,当水温由22 ℃骤降至19 ℃或16 ℃时,鱼卵的孵化率和死亡率无明显变化,而胚胎发育和仔鱼的生长发育均减缓,仔鱼的死亡率提高;水温超出适温范围,由22 ℃骤降至13 ℃或10 ℃时,对鱼卵和仔鱼造成致命的冷冲击伤害,48 h累积死亡率分别为84.6%~100%和72.1%~98.2%。由此推测:当水温骤降超出适温范围后,大黄鱼的早期发育阶段遭受致命的冷冲击伤害,从而影响种群补充和年龄结构。  相似文献   

无人直升机搭载大气颗粒物采样装置的前期地面评估     

李杨  马舒庆  贾小芳 《气象与环境科学》2016,39(2):132-136

与搭载气溶胶观测和分析仪器测量相比,利用无人直升机搭载气囊采集高空大气颗粒物是一种经济、便捷和安全的采集方式。为了解无人直升机采样装置的采样效果,选择2014年10月至2015年3月的4次重污染天气过程,由无人直升机搭载气囊采集大气颗粒物,然后利用气溶胶采样器采集气囊内的大气颗粒物样品并计算采样时间,再利用气溶胶采样器采集相同时间段内的地面大气颗粒物(气囊外),并将两者进行对比。结果表明:在稳定的污染天气条件下,采集气囊内的大气颗粒物,与相同时间段内利用气溶胶采样器直接采集气囊外的大气颗粒物相比,两种方式采集到的大气颗粒物质量最大差值29%,最小差值11%,平均为21%;利用无人直升机的大气采样装置采集大气颗粒物对碳气溶胶组分影响很小,气囊内与气囊外OC/TC最大相差2.0%,最小相差0.5%。上述结果表明,无人直升机的大气采样装置有比较好的采集效率,利用气囊这种经济、便捷、安全的方式,搭载在无人机平台上,采集高空大气是一种获取气溶胶垂直廓线的有效方法,有望在未来的气溶胶气候和环境研究中提供宝贵数据。  相似文献   

Re‐establishment of soil water repellency after destruction by intense burning in a Mediterranean heathland (SW Spain)     

Antonio Jordán  Félix A. González  Lorena M. Zavala 《水文研究》2010,24(6):736-748

Soil water repellency has been conventionally considered as a fire‐induced effect, but an increasing number of studies have suggested that natural background repellency occurs in many soil types, and many of them have suggested that water repellency can be re‐established over time after being destroyed. An experimental fire was conducted to study changes of the soil surface during the first 18 months following intense burning. The main objectives of this paper are as follows: (1) to investigate in situ water repellency changes at three soil depths (0, 2 and 4 cm) immediately after burning; (2) to evaluate the medium‐term evolution of water repellency under field conditions; and (3) to outline the main hydrological consequences of these changes. Also, different water repellency tests (water drop penetration time, ethanol percentage test (EPT) and contact angle (CA) between water drops and the soil surface) were carried out for comparison purposes. Field experiments showed that soil water repellency was partly destroyed after intense burning. Changes were relatively strong at the soil surface, but diminished progressively with depth. Levels of water repellency were practically re‐established 18 months after burning. This suggests that water repellency in the studied area is not necessarily a consequence of fire, but can instead be a natural attribute. Finally, although limited in time, destruction of soil water repellency has important consequences for runoff flow generation and soil loss rates, and, indirectly, for water quality. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

注水诱发地震的震源应力场和尾波衰减特征          下载免费PDF全文

赵根模  杨港生 《地震地质》1990,12(4):303

利用区域性台网记录测定了任邱油田注水诱发地震的震源应力场和尾波衰减特征,结果表明地壳上层有很大水平应力,断层面解受注水井附近局部原生断层影响与华北现代应力场的优势破裂方向和错动方式有差别。地震应力降分布范围为0.2—3.0巴。平均尾波Q_0值为75,属于地壳上部沉积岩层的正常情况,发现在时间上表现出与注水量增减有关的波动。在空间上表现出震群密集区Q_0值较外围区偏低的特点  相似文献   

Confidence intervals for earthquake source parameters   总被引：2，自引：0，他引：2  

G. A. Prieto  D. J. Thomson  F. L. Vernon  P. M. Shearer  R. L. Parker 《Geophysical Journal International》2007,168(3):1227-1234

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An effective approach to determine the dynamic source parameters     

Xiaofei Chen  Keiiti Aki 《Pure and Applied Geophysics》1996,146(3-4):689-696

In this study, we present a new and effective method to determine the dynamic source parameters (i.e., stress drop and strength distribution). We first assume that the kinematic source parameters, i.e., the slip and rupture time distributions on the fault plane, are known from the previous source inversion studies. Then, using the seismic source representation theorem we determine the dynamic stress field on a fault plane from known kinematic parameters. Finally, we determine the strength of the fault defined as the peak stress just before the rupture. We have tested the validity of this method by using an illustrative two-dimensional analytical example. To assess the applicability of this method, we have applied it to study the 1979 Imperial Valley earthquake, and obtained consistent results with those ofMiyatake's (1992) andQuin's (1990). Compared with previous methods, this new method is simple, straightforward and accurate, and needs much less calculation. Therefore, it is expected to be useful in exploring the seismic source process.  相似文献   

伊舒断裂带南、北段震源参数研究          下载免费PDF全文

董瑞树  刘志平 《地震地质》1996,18(1):59-65

利用时间城小地震地震图的方法，研究了震源参数与介质特性的差异。据初步研究结果，伊通－舒兰断裂南、北两段的震源应力降与Ｑ值存在差异。该方法是断层的震源深度范围内介质特性研究的补充，为断裂的分段提供一个重要方法  相似文献   

天津地区小震应力状况     

薛志照  杨港生 《地震地磁观测与研究》1992,13(1):34-39

本文测定了天津地区1985—1990.9年间M_L=3.0以下小震的震源参数,共125次。结果表明:地震应力降△σ一般都不高,多数低于1.3Mpa;区域剪切应力和地震应力降均有明显的增高趋势。1989年末开始下降。由P波测定的介质Q值蓟县平均为350,宝坻、宁河、静海为250,天津西稍高。小震平均震源机制主压应力轴由北西9°,向西偏转26°。这些变化,不仅反应本地区应力调整过程,而且是华北区域应力变化过程的局部显示。  相似文献   

岩石粘滑的自锁模型及数值模拟     

陈铁民  陶振宇 《地震工程学报》1993,15(1):39-44

本文根据岩石摩擦的自锁模型,通过数值模拟讨论了围压和围压介质刚度对粘滑及其应力降的影响。结果表明:围压的增大有利于发生粘滑;粘滑应力降随围压的增大而增大;天然地震应力降低于室内粘滑应力降是由围压介质刚度引起的。  相似文献   

喀喇沁玻基橄辉岩中的磷酸盐质熔体及磷灰石   总被引：2，自引：0，他引：2  

邵济安  王志海 《岩石学报》2000,16(3):449-453

磷酸盐在本文讨论的坡基橄辉岩中以多种形式产生,有早期结晶的磷灰石斑晶;有熔离的磷酸盐质熔浆液滴;也有晚期穿入橄榄石斑晶的磷酸盐质细脉,表明元素磷活跃在岩浆演化的每一个阶段。磷酸盐质熔浆液滴的存在,说明磷酸盐质熔体可能是由于岩浆的熔离作用而形成的。沿着橄榄石晶格生长石出现的磷酸盐质玻璃细脉则进一步证实地幔中含磷流体不但存在,而且具有很强的活动性。  相似文献