The Statistical Analysis of Migration of Strong Earthquakes-Taking the North China Region as an Example

The migration of strong earthquakes is an important research topic because the migration phenomena reflect partly the seismic mechanism and involve the prediction of tendency of seismic activity. Research on migration of strong earthquakes has mostly focused on finding the phenomena. Some attempts on getting regularity were comparatively subjective. This paper suggests that there should be indices of migration in earthquake dataset and the indexes should have statistical meaning if there is regularity in the migration of strong earthquakes. In this study, three derivative attributes of migration, i.e., migration orientation, migration distance and migration time interval, were statistically analyzed. Results in the North China region show that the migration of strong earthquakes has statistical meaning. There is a dominant migration orientation (W by S to E by N), a dominant distance (≤100km and on the confines of 300～700km), and a dominant time interval (≤1a and on the confines of 3～4a). The results also show that the migration will differ slightly with different magnitude range or earthquake activity phase.     

Post-depositional modification of NO-3 in snow layers at EastAntarctica and at the headwater of ürumqi River

Acidic species, such as Nitrate, in polar snow and firn layers are “reversibly” deposited, and are sufficiently volatile to undergo significant postdepositional exchange between snow/firn and the atmosphere. Through comparison of the snowpit and snowpack nitrate concentrations from central East Antarctica and the headwater of ürumqi River, we conclude that the nitrate peaks in the uppermost surface snow layers in central Antarctica are not related to an atmospheric signal and must account for post-depositional effects. Such effects, however, are not found in the surface snowpack nitrate profiles from the headwater of ürumqi River. Two reasons may account for the post-depositional difference. At first, nitrate in the polar snow and firn layers appears to be hydrated ion, which can be taken up by the atmosphere, while at the headwater of ürumqi River it seems mainly as mineral ion, which assembles the behavior of aerosol-derived species that are “irreversibly” deposited and do not undergo significant post-depositional exchange with the atmosphere. Secondly, the chemical features of the snow and ice on the Antarctica are mainly determined by wet deposition, to the contrary, dry deposition is more significant at the headwater of lUrumqi River than that on the East Antarctic Plateau.     

腾冲火山区剪切波和尾波衰减初步研究

用云南腾冲火山地区观测的地震数字化记录进行了尾波和剪切波的衰减测量。用AkiandChouet和Sato单次散射模型获得 5 2秒和 18秒流逝时间尾波的品质因子分别为Qc (f) =5 7×f- 0 94和Qc (f) =2 6×f- 0 95 ,表明地壳上部和地壳上地幔的地震波衰减频率变化率一致。两者均未显示出活火山地区尾波衰减的异常特征。尾波掠过空间椭球的平均半轴 ,前者约为 80km ,大大超出了腾冲火山分布的地理范围 ,后者约为 30km ,在腾冲火山分布的地理范围之内。用尾波规一双台S波振幅比法进一步缩小所用地震波掠过的空间 ,最后获得了S波随频率的衰减有类似于前人报导的活火山地区尾波频率衰减的特征 :相对于低频 (1 5～ 6Hz) ,高频 (6～2 0Hz)的Q- 1s 变化很小。从地表位置看 ,腾冲最年青的全新世的马鞍山和老龟坡火山就在S波掠过范围内 ,打鹰山火山也在近旁。这一结果表明在这三座火山体之下存在低速高衰减体。火山或处于休眠状态 ,或在消亡过程之中。     

硫酸盐还原菌与铁还原菌联合释放含砷水铁矿中砷及渗透性研究

水铁矿是土壤中常见的铁氧化物矿物,也是主要的载砷矿物。从水铁矿中释放砷,是缓解土壤砷污染的一种途径。本文拟通过硫酸盐还原菌(SRB)和嗜酸铁还原菌(JF-5)生物还原含砷水铁矿(As-Fh),促进其砷释放,以达到土壤修复目的。为此,利用采集自湖南石门矿区的典型含砷水铁矿,进行两种微生物摇瓶实验和生物注入水铁矿柱实验,探究水铁矿释放砷浓度及形态、生物溶解过程中悬浮颗粒物变化以及体系渗透性问题。研究结果表明：(1)在两个循环周期下,从释放的砷总量可看出,JF-5+SRB操作>JF-5+JF-5操作>SRB+JF-5操作>SRB+SRB操作,对应这些操作每克水铁矿能够分别释放16.4、16.2、7.3和3.3 mg的砷;(2)水化学分析也表明同等操作下SRB能够提供比JF-5更强的还原性;(3)生物柱实验表明,相比于SRB来说,JF-5的注入能够产生平均浓度1 419 mg/L的铁系悬浮颗粒物,是SRB的7.25倍;同时两种生物操作过程下,SRB柱体系渗透性(平均水压差为0.51 psi)显著优于JF-5(平均水压差为2.22 psi),高悬浮颗粒的分散是引起渗透性变化的主因。上述结果证明连续注入SRB于水铁矿体系,是一种有效的降低土壤中砷浓度的技术。     

刘公岛海洋牧场底层海水溶解氧浓度的变化特征

自20世纪50年代发现长江口的低氧现象以来,众多学者对其展开了研究,但是对于该海域的长时间连续观测仍然较为缺乏,对低氧形成的动态过程难以有清楚的认知。利用大戢山西南海域的坐底观测站2020年1月至5月的底层溶解氧（Dissolved Oxygen, DO）数据,分析了该站点处溶解氧的变化特征,发现观测期间底层溶解氧出现了2次发展过程完全不同的低氧现象：第一次低氧形成过程较为缓慢,在2020年1月至4月,溶解氧缓慢降低,到4月出现并维持低氧;第二次低氧形成较为迅速,在5月中下旬,溶解氧在10 d内从接近饱和迅速降低到低氧状态。通过对2次低氧形成过程中不同环境要素的分析发现,1月至3月溶解氧降低主要原因是升温导致的氧溶解度下降以及沉积物耗氧,4月则是有机物分解导致的低氧,同时4月上中旬的弱风条件有利于形成层结,维持低氧,在5月初出现持续的强风混合海水,第一次低氧过程结束。而大风混合海水后也将底层营养盐输送到表层,使得海表浮游植物大量繁殖,出现赤潮,赤潮末期大量浮游植物死亡沉降到海底进行分解,再加上5月中下旬风混合较弱,使得5月末又迅速进入低氧状态。借助于连续的观测数据,对于2020年春季2次连续低氧的分析可以补充对长江口低氧季节变化的认知,为研究长江口的春季低氧变化特征及形成机制提供重要参考。

     

青海湖裸鲤内脏发光细菌的分离和鉴定

2009-2013年,从青海湖裸鲤内脏器官中共分离获得6株发光细菌,编号依次为Q1、Q2、Q3、Q4、Q5、Q6.这6株发光细菌细胞壁革兰氏染色均为阴性,细胞为杆状,大小为(0.5~0.8)μm×(1.0~1.5)μm,具有单极生鞭毛,有运动性.氧化酶和接触酶均呈阳性反应,能发酵葡萄糖产酸;吲哚试验和V-P试验均为阳性反应,能分泌淀粉酶、明胶酶、DNA酶,能将硝酸盐还原为亚硝酸盐.最适生长温度为20~25℃,最适生长pH为8.5~9.0.16S rDNA基因序列分析结果表明,6株发光菌与其亲缘关系最近的属为Vibrio(弧菌属),该属内和此次实验的6株发光菌亲缘关系最近的种Vibrio anguillarum(鳗弧菌)的16S rDNA序列相似值为99.57%.Biolog GenⅢ鉴定结果显示,该实验的6株发光菌在有氧条件下,在提供的71种碳源中,只能利用其中的30种,其中,糖类12种,氨基酸类5种,羧酸类4种,聚合物类2种,其他类7种.结合6株发光菌的形态学特征、生理生化特性、Biolog Gen III鉴定结果和分子生物学特性,将菌株鉴定为Vibrio anguillarum.该菌所具有的发光特性为首次报道.