青海龙羊峡超低频电磁辐射在中强震前的短期(短临)异常特征及单台预报效能

根据青海龙羊峡电磁台自1991年9月以来的资料，对电磁波辐射在震前的异常特征进行了分析总结。地震往往发生在电磁波异常结束后，电磁波在一组异常中出现显著异常是地震进入短期(短临)异常的主要特征。显著异常判断指标是一次地震中异常幅度(产生的场强)最大的或异常持续时间最长的异常。通过对有震异常、无震异常和漏报的统计，龙羊峡电磁波辐射的预报效能并不高。     

北京五里营井流体异常原因及解决办法

2010年7月3日延庆地震台五里营井流体测项均出现大幅波动现象。本文台站人员通过科学系统分析,确定此异常变化是由于该井泄流管最高端憋气造成,并采用类似暖气跑风的原理,对泄流管进行了改造,使所有流体测项恢复正常观测。     

2002年8月3日沙城4.4级地震震源特征

2002年8月3日沙城ML4．4地震是该年7个月以来，首都圈地区发生的显著地震，虽然该地震震级不大，但怀来台体应变的短临异常十分显著。作者主要介绍了该地震前体应变异常特征，同时介绍了地下流体测项阳原三马坊数字气氡异常和怀4井水汞异常及预报情况。     

临震电磁波异常

本文介绍了1983年6月24日越南莱州M=7.0级地震前后楚雄地震台“磁引信”仪器记录到的电磁波异常。发现主震前后出现的异常电磁波的波形、频率、振幅都不相同,并指出利用震前电磁波异常作地震短临预报的可能性。本文还就地震辐射电磁波的一些问题进行了讨论。     

景泰5．9级地震前平安地温及电磁波短临异常特征

介绍了平安台地温,电磁波观测点基本概况以及该点地温与电磁波在2000年6月6日甘肃景泰地震前的短临异常特征,初步探讨了异常形成的机理,认为平安台2种观测手段互初性好,有一定的映震能力,利用其同步异常信息对一定范围内的地震做出一定程度的预报是可能的。     

河北文安5.5级地震前天津地区流体短期前兆异常分析

以河北文安5.5级地震为例,分析了地震前天津地区流体测项的异常变化。结果表明,天津王3井、王4井水汞、潘庄井及双桥1井水位在震前都出现了明显的短期前兆异常。     

山西晋城市地震电磁波台网观测数据动态特征分析

分析总结山西晋城市电磁波台网6个子台观测资料的正常动态特征以及各子台存在的干扰因素,并对2011年发生在台网周边的2次3.0级以上地震出现的异常特征进行分析研究。     

江苏及邻近地区地震电磁辐射异常与地震关系

对这20多年来江苏及其邻区的地震前的电磁波观测资料进行了整理,对出现的异常信息和地震的对应关系进行了统计分析,分析结果表明,电磁波异常信息与地震三要素有一定的对应关系,并对电磁波的性质从电磁波产生的机制和传播方式两个方面进行了探讨。     

对汶川8.0级地震前四川地区地电地磁观测异常的分析与思考

研究了汶川8.0级地震前四川地区模拟和数字地电、地磁类观测资料。四川地区地电6台站的26测项模拟观测,在汶川8.0级地震前仅出现1项中期异常,异常台站比1/6=0.17;异常测项比为1/26=0.04。对"九五"到"十五"期间四川地区数字化改造或数字地电观测资料,没有分析检测出异常项。四川地区6个台的地磁垂直分量整点值的日变形态在震前2天出现波谷分裂的异常现象,由于平时出现此类异常频繁,若用于预测无统计学的显著意义。可见汶川8.0级地震前四川地区地电和地磁类观测资料结果出现的异常现象比例是极低的。同时对疑似或有争议的异常测项进行分析说明,对汶川8.0级地震前电磁类异常少的原因进行了讨论。     

汶川8.0级地震前后表层水温的异常变化研究

对汶川8.0级地震震中周围800km范围内73个井孔的表层水温资料进行了分析。根据设定的异常与不确定性异常判定依据,发现有9个井孔出现了前兆异常;有5个井孔的异常不能确定是否为前兆异常;有3个井孔出现了典型非前兆异常变化;其余未出现任何异常变化。分析认为异常存在早期、中期和晚期三个阶段,表现为缓变、突变和向下的阶梯状变化。对9个异常井孔的同井水位、气氡等其它流体测项以及同台或邻近台站形变仪器(钻孔应变、钻孔倾斜、洞体应变等)在表层水温异常变化时段内的动态变化特征进行了对比,发现地壳形变与表层水温在异常的晚期阶段具有一定的相关关系;而同井水位与表层水温异常的关系不大。     

中国特有种大型桡足类舌状叶镖水蚤(Phyllodiaptomus tunguidus)在广东水库中的分布特征

舌状叶镖水蚤(Phyllodiaptomus tunguidus)是我国特有的大型哲水蚤,主要分布在我国华南地区.根据2000年对广东省19座典型大中型水库的2次采样和2002年对流溪河水库和新丰江水库的5次采样,重点测定了流溪河水库、新丰江水库和鹤地水库等3座大型水库中舌状叶镖水蚤个体体长及形态参数,分析了广东省大中型水库中舌状叶镖水蚤的种群与个体大小的分布特征.在对19座水库的2次采样中,11座水库发现该种成体,其中5座水库在丰水期没有出现该种的成体,6座水库在丰水期和枯水期都有该种类成体的出现.丰水期与枯水期舌状叶镖水蚤的平均丰度分别为0.465ind./L和0.996ind./L.舌状叶镖水蚤主要出现在大型水库中,特别是贫营养的大型水库,其丰度主要由食物数量、质量与捕食压力所决定.2002年,流溪河水库丰度和新丰江水库舌状叶镖水蚤全年的平均值为1.308ind./L和0.294ind./L,丰水期高于枯水期.在个体大小和形态特征上,2座贫营养水体——流溪河水库、新丰江水库的舌状叶镖水蚤的体长与第一触角长度均大于中营养水体——鹤地水库,这种形态上的差异是由鱼类捕食方式(滤食或选择性捕食)所决定.     

鄱阳湖流域干旱气候特征研究

本文利用鄱阳湖流域127个站点1960-2007年逐日降水和温度资料,选用Z指数对鄱阳湖流域的气象干旱进行分析,并将干旱分为偏旱、大旱和特旱三个等级.研究结果表明鄱阳湖流域干旱基本呈现出南少北多、南强北弱的空间分布形式.鄱阳湖流域7-12月发生的干旱以偏旱为主,大旱和特旱主要出现在1-6月.线性趋势变化分析表明,2000年以来干旱范围和干旱强度均呈现出增加的趋势,其中,2003、2004和2007年的干旱较为严重.2003年大部分月份偏旱范围广、强度大,全年大旱和特旱出现的范围均较小,但3-4月和6-7月的大旱和特旱强度较大;2004年大部分月份偏旱范围和强度均相对较小,但在3月和6月出现范围较大且强度较强的大旱和特旱;2007年干旱分布更为极端,仅在7、10和11月出现范围较广或强度较大的偏旱,而在5月集中出现面积超过80%的大旱和特旱.     

有机和常规农业管理方式下的浮游植物群落特征及其影响因素

为了解不同农业施肥管理方式对水体浮游植物群落的影响,本研究以江苏句容戴庄有机示范村和常规农业管理区池塘浮游植物为对象,分析冬夏两季浮游植物群落特征及相关水环境因子.结果表明：冬季有机和常规农业区域的浮游植物分别检到7门95种和7门111种,夏季分别检到7门102种和6门112种,有机农业区浮游植物由冬季的隐藻-绿藻型向夏季的蓝藻-绿藻型变化,常规农业区从隐藻-绿藻型向蓝藻-硅藻型变化,蓝藻逐渐取代隐藻的优势地位.夏季各池塘浮游植物alpha多样性没有显著的区域差异,但冬季常规农业区浮游植物物种丰富度、蓝藻和裸藻的Shannon-Wiener多样性指数显著较高.指示物种分析显示,谷皮菱形藻（Nitzschia palea）和梅尼小环藻（Cyclotella meneghiniana）为有机农业区指示物种,而梭形裸藻（Euglena acus）、针形纤维藻（Ankistrodesmus acicularis）、肘状针杆藻（Synedra ulna）和狭形纤维藻（Ankistrodesmus angustus）为常规农业区指示物种,此6种藻为中、富营养化藻类,说明水体氮磷营养盐浓度较高,这与周围农田氮磷流失密切相关.Pearson相关性分析表明,有机农业区浮游植物alpha多样性与氮磷浓度的相关性不显著,但常规农业区浮游植物物种丰富度和Pielou均匀度与磷酸盐、总氮、氨氮和pH值显著相关.Mantel检验表明,有机农业区群落相异性仅在冬季受到总氮和氨氮的显著影响;而常规农业区在冬夏季受到氮磷两类营养盐的交替影响.本研究结果初步揭示了有机和常规农业区水体浮游植物群落结构特征及其影响因素,为区域水生生物多样性保护与稻田施肥管理的优化提供科学基础.     

Structure and Significance of S-wave Velocity and Poisson’s Ratio in the Crust beneath the Eastern Side of the Qinghai-Tibet Plateau

The receiver functions of body waves of distant earthquakes obtained for the regions beneath 41 digital stations (Lhasa and GANZ in Tibet, Mandalay and Rangoon in Myanmar, SHIO in India, CHTO in Thailand, and station network in Sichuan and Yunnan) were used to invert for S-wave structure in the crust and upper mantle in Sichuan, Yunnan, and their surrounding areas. Meanwhile the distribution characteristics of the Poisson’s ration and the crustal thickness in Sichuan and Yunnan areas were also obtained. Results indicate that the depth of Moho beneath the eastern side of Qinghai-Tibetan plateau varies strikingly. It is obvious that the greatest changes in crustal thickness occur in a north-south direction. The crustal thickness decreases from north to south, being as thick as 70 km in eastern Tibet, the northern portion of our area of interest, and less than 30 km in Chaing Mai and Rangoon, the southern portion of our area. There are, however, exceptions regarding the trend. The thickness exhibits an east-west variation trend in the area from Ma’erkong-Kongding in Sichuan to Lijiang in Yunnan. In general the Jinpingshan-Longmenshan fault and Anninghe fault can be taken as the boundaries of this exception area. The thickness in Kongding in the west is 68 km, while it is only 39 km in Yongchuan in the east. Moreover the Poisson’s ratio values in the blocks of central Sichuan and Sichuan-Yunnan Diamond are high, and a low velocity layer in the crust of this area can be obviously detected. The distribution characteristics of the high Poisson’s ratio and the low velocity of the crust in this block correspond to the tectonic structure, being in contrast with the surrounding areas. Combining with the distribution features of the modern tectonic stress field, it is deduced that the Sichuan-Yunnan area is probably the channel through which the materials of the lithosphere flow eastward.     

Distribution of trace elements in subcellular fractions of three aquatic birds

This study investigated the subcellular distribution of Cu, Zn, Cd and Ag in liver of mallard (Anas platyrhynchos), spot-billed duck (A. poecilorhyncha) and great cormorant (Phalacrocorax carbo) to better understand metal fractionation and dynamics in avian liver. Most of the total Cu, Zn, Cd and Ag were present in hepatocytosol, and their concentrations increased with total hepatic levels in all the three avian species. Copper, Zn and Cd in hepatocytosol were present mostly in metallothionein fractions (MTs), and Cu and Cd contents in this fraction were positively correlated with hepatocytosol levels in all the species. Silver was observed mostly in both high-molecular weight and MT fractions in hepatocytosol in mallard and great cormorant, whereas it was present in both low-molecular weight and MT fractions in spot-billed duck, suggesting that distribution of Ag in the hepatocytosol was species-specific. The elution profile of metals in MT fractions revealed six metallic peaks in mallard and spot-billed duck, and three peaks in great cormorant, implying the presence of multiple MT isoforms in the liver of these avian species. The present study demonstrated that MTs are closely associated with metal regulation, especially Cu and Cd, in these three aquatic birds.     

Residues of selected antibiotics in water and mud from shrimp ponds in mangrove areas in Viet Nam

In recent years, antibiotics have been used widely in intensive shrimp culture and this may lead to their contamination of the environment. Surveys on residues of trimethoprim (TMP), sulfamethoxazole (SMX), norfloxacin (NFXC) and oxolinic acid (OXLA) in water and mud in shrimp ponds in mangrove areas were conducted in the north as well as in south of Viet Nam in July and August, 2002. The results show that these antibiotics are found in all samples in both shrimp ponds and surrounding canals. The highest concentrations of TMP, SMX, NFXC and OXLA are 1.04, 2.39, 6.06, and 2.50 ppm in water samples; and 734.61, 820.49, 2615.96, 426.31 ppm (based on wet mud weight), respectively. The comparison of antibiotics residues between study sites and types of shrimp ponds will be discussed in this paper. The results also suggest that antibiotics residues may cause harmful effect on ecosystems in the study sites.     

Quench rates in air, water, and liquid nitrogen, and inference of temperature in volcanic eruption columns

We apply a geospeedometer previously developed in this lab to investigate cooling rate profiles of rhyolitic samples initially held at 720–750°C and quenched in water, liquid nitrogen, and air. For quench of mm-size samples in liquid nitrogen and in air, the cooling rate is uniform and is controlled by heat transfer in the quench medium instead of heat conduction in the sample. The heat transfer coefficient in ‘static’ air decreases with increasing sample size. For quench of mm-size samples in water, heat transfer in water is rapid and the cooling rate is largely controlled by heat conduction in the sample. Our experimental results are roughly consistent with previous calculations for cooling in air and in water (although constant heat transfer coefficients were used in these calculations), but cooling rate in liquid nitrogen is only 1.8–2.3 times that in ‘static’ air, and slower by a factor of 2 than calculated by previous authors. Cooling rate in compressed airflow is about the same as that in liquid nitrogen. The experimental results are applied to interpret cooling rates of pyroclasts in ash beds of the most recent eruptions of the Mono Craters. Cooling rates of pyroclasts are inversely correlated with sample size and slower than those in air. The results indicate that the hydrous species concentrations of the pyroclasts were frozen in the eruption column, rather than inside ash beds or in flight in ambient air. From the cooling rates, we infer eruption column temperature in a region where and at a time when hydrous species concentrations in a pyroclast were locked in. The temperature ranges from 260 to 570°C for the most recent eruptions of Mono Craters. These are the first estimates of temperatures in volcanic eruption columns. The ability to estimate cooling rates and eruption column temperatures from eruptive products will provide constraints to dynamic models for the eruption columns.     

Seasonal patterns of runoff and erosion responses to simulated rainfall in a badland area in Mediterranean mountain conditions (Vallcebre,southeastern Pyrenees)

Regolith surface characteristics and response were examined over a three‐year period in a badland area in a Mediterranean middle‐mountain zone near Vallcebre (Eastern Pyrenees). Preliminary work carried out in this area indicated clear seasonal patterns of regolith properties driven by frost heaving in winter and crusting and erosion in the rest of the year. Rainfall simulations were performed with a small portable nozzle simulator in order to study seasonal changes in runoff generation, erosion rates and raindrop effect on bulk density changes. The results showed large seasonal variations in runoff and erosion responses. In?ltration rates after runoff start were correlated with precipitation depth before runoff start; runoff generation was therefore related to regolith saturation only to a very limited extent. Erosion rates were more controlled by runoff rates than by the weakness of regolith against raindrop splash, and sediment grain size increased with concentration. The combined role of antecedent regolith moisture and bulk density explained most of the seasonal variability in in?ltration, bulk density changes during rainfall and erosion rates, but some seasonal differences in sediment detachability were not explained by these variables and may be attributed to changes in roughness. Overall, runoff and erosion responses were relatively stable during spring and autumn, whereas wide variations in in?ltration rates and sediment detachment occurred in winter and summer respectively. Experiments conducted in a single season would have produced poorly representative, if not erroneous, results. Copyright © 2004 John Wiley & Sons, Ltd.     

Recent climatic trends and linkages to river discharge in Central Vietnam

In this study, change in rainfall, temperature and river discharge are analysed over the last three decades in Central Vietnam. Trends and rainfall indices are evaluated using non‐parametric tests at different temporal levels. To overcome the sparse locally available network, the high resolution APHRODITE gridded dataset is used in addition to the existing rain gauges. Finally, existing linkages between discharge changes and trends in rainfall and temperature are explored. Results are indicative of an intensification of rainfall (+15%/decade), with more extreme and longer events. A significant increase in winter rainfall and a decrease in consecutive dry days provides strong evidence for a lengthening wet season in Central Vietnam. In addition, trends based on APHRODITE suggest a strong orographic signal in winter and annual trends. These results underline the local variability in the impacts of climatic change at the global scale. Consequently, it is important that change detection investigations are conducted at the local scale. A very weak signal is detected in the trend of minimum temperature (+0.2°C/decade). River discharge trends show an increase in mean discharge (31 to 35%/decade) over the last decades. Between 54 and 74% of this increase is explained by the increase in precipitation. The maximum discharge also responds significantly to precipitation changes leading to a lengthened wet season and an increase in extreme rainfall events. Such trends can be linked with a likely increase in floods in Central Vietnam, which is important for future adaptation planning and management and flood preparedness in the region. Copyright © 2012 John Wiley & Sons, Ltd.