Cold deep water in the South China Sea

Two deep channels that cut through the Luzon Strait facilitate deep (>2000 m) water exchange between the western Pacific Ocean and the South China Sea. Our observations rule out the northern channel as a major exchange conduit. Rather, the southern channel funnels deep water from the western Pacific to the South China Sea at the rate of 1.06 ± 0.44 Sv (1 Sv = 10⁶ m³s⁻¹). The residence time estimated from the observed inflow from the southern channel, about 30 to 71 years, is comparable to previous estimates. The observation-based estimate of upwelling velocity at 2000 m depth is (1.10 ± 0.33) × 10⁻⁶ ms⁻¹, which is of the same order as Ekman pumping plus upwelling induced by the geostrophic current. Historical hydrographic observations suggest that the deep inflow is primarily a mixture of the Circumpolar Deep Water and Pacific Subarctic Intermediate Water. The cold inflow through the southern channel offsets about 40% of the net surface heat gain over the South China Sea. Balancing vertical advection with vertical diffusion, the estimated mean vertical eddy diffusivity of heat is about 1.21 × 10⁻³ m²s⁻¹. The cold water inflow from the southern channel maintains the shallow thermocline, which in turn could breed internal wave activities in the South China Sea.     

基于GPS观测研究中国东北地区现今地壳形变特征

基于中国东北和俄罗斯远东东南部2012—2017年的GPS观测数据, 利用包含年周期、 半年周期、 线性项和阶跃项的函数模型拟合GPS站坐标时间序列, 得到ITRF2014下的速度场, 并进一步转换到欧亚参考框架下得到相对欧亚板块的速度场。 基于多尺度球面小波方法解算应变率场, 并分析了其空间分布特征, 同时研究了各GPS站对2011年日本东北M_W9.0大地震的震后松弛响应特征和背景形变场特征。 结果表明: ① 若不扣除日本东北大地震的松弛效应, 相对欧亚板块中国东北主体上表现为东南方向运动, 在依兰—伊通断裂和嫩江断裂带之间, 地壳表现为逆时针旋转, 其他区域向东南方向运动, 方向一致性较好, 在敦化—密山断裂东侧速度大小明显增加。 敦化—密山断裂和依兰—伊通断裂两侧拉张量分别为3.96±0.04 mm/a和0.71±0.05 mm/a, 两条断裂的剪切运动不明显。 总体上, 面应变率显示出NW—SE向的拉张和NE—SW向的挤压, 面应变率显示出依兰—伊通断裂南端、 嫩江断裂带北端和俄罗斯远东东南部呈挤压状态。 在依兰—伊通断裂、 敦化—密山断裂南侧以及俄罗斯远东东南部最大剪应变率相对较大。 ② 各GPS测站对2011年日本东北M_W9.0大地震震后松弛的响应整体上表现为东南向运动, 松弛形变量随震中距增加而减小。 松弛效应的面应变率总体上表现为NW—SE向的拉张和NE—SW向的挤压, 面应变率显示出依兰—伊通、 敦化—密山断裂南端、 嫩江断裂带北端以及俄罗斯远东地区具有挤压特征, 其他地区表现为拉张特征。 中国与俄罗斯远东边界南端存在一个明显的最大剪应变率高值区。 ③ 扣除日本东北M_W9.0大地震引起的松弛变形后, 总体上面应变率仍然表现为NW—SE向的拉张和NE—SW向的挤压, 面应变率最大值仍然位于依兰—伊通断裂和敦化—密山断裂南端、 第二松花江断裂带以及俄罗斯远东和中国边界最南段。 在依兰—伊通断裂、 敦化—密山断裂南端, 中国与俄罗斯远东边界南端的最大剪应变率高值区仍然存在, 表明这些地区应变积累较快, 并且一直在持续。     

2016年新疆阿克陶MS6.7地震同震形变特征和断层滑动分布反演

本文针对2016年11月25日在新疆阿克陶发生的地震, 用差分干涉测量技术(D-InSAR)对3种不同观测模式的升、 降轨数据进行处理, 提取了多视线向的同震形变场; 根据不同模式的LOS向形变量, 构建形变分解模型, 将其分解为垂直向形变量和沿断层走向形变量; 结合同震形变场特征与震源机制解, 采用单断层模型, 利用梯度下降法(SDM), 以Multi-LOS向形变进行约束, 反演了阿克陶地震的同震滑动分布特征。 研究结果表明, 升、 降轨LOS向同震形变场在发震断层两侧具有不同的形变特征, 发震断层走向近EW向; LOS向形变量分解表明, 此次地震破裂以右旋走滑为主; 滑动分布反演的形变残差介于0~5 cm之间, 发震断层的滑动量主要位于2~16 km深部, 最大滑动量可达1.02 m, 位于断层面深部5.83 km处, 最大滑动量处的滑动角为185.24°; 平均滑动角为181.32°, 平均滑动量为0.12 m; 滑动分布反演也证明该地震为右旋走滑破裂事件, 与LOS向形变分解结果一致; 当剪切模量μ=3.2 GPa时, 反演得到的地震矩震级约M_W6.6。     

Co-seismic Coulomb stress changes on the northern Tanlu fault zone caused by the Tohoku-Oki MW9.0 earthquake*

Based on the spherical earth dislocation theory and a fault slip model of the Tohoku-Oki M_W9.0 earthquake, the co-seismic Coulomb failure stress changes (ΔCFS) on the northern Tanlu fault zone at depths of 0–40 km are calculated. By comparing two sets of results from the spherical earth dislocation theory and the semi-infinite space one, the effect of earth curvature on the calculation results is analyzed quantitatively. First, we systematically summarize previous researches related to the northern Tanlu fault zone, divide the fault zone as detailed as possible, give the geometric parameters of each segment, and establish a segmented structural model of the northern Tanlu fault zone. Second, we calculate the Coulomb stress changes on the northern Tanlu fault zone by using the spherical earth dislocation theory. The result shows the Coulomb stress changes are no more than 0.003 MPa, which proves the great earthquake did not significantly change the stress state of the fault zone. Finally, we quantitatively analyze the disparities between the results of semi-infinite space dislocation theory and the spherical earth one. The average disparity between them is about 7.7% on the northern Tanlu fault zone and is 16.8% on the Fangzheng graben, the maximum disparity on this graben reaches up to 25.5%. It indicates that the effect of earth curvature can not be ignored. So it’s necessary to use the spherical earth dislocation theory instead of the semi-infinite space one to study the Coulomb stress change in the far field.     

华北地区中东部岩石圈挠曲与均衡特性以及地震活动性分析

华北地区中东部涵盖北京、天津以及即将建设的雄安新区等大型城市,区内发育了张渤地震带等多条大型活动断裂,地震活动性较强,历史上发生过多次6级以上地震.本文利用Fan小波的布格重力异常一致性方法研究该区的岩石圈有效弹性厚度和均衡调整初始加载比分布,同时基于均衡调整方法计算该区垂向构造应力分布,并将以上结果与历史地震活动进行统计分析.岩石圈挠曲分析表明,华北地区中东部的岩石圈有效弹性厚度为10~65 km,分布特征为自东南向西北逐渐减小.均衡调整初始加载比为0.5~0.8,表明现今的岩石圈挠曲状态主要由莫霍面加载形成.该区地壳承载的垂向构造应力约为-20~20 MPa,中西部地区垂向构造应力向上,东北和西南地区向下.统计分析结果显示,华北地区中东部的地震活动性随着岩石圈有效弹性厚度和均衡调整初始加载比的增加而减弱,垂向构造应力零值区域地震活动性较弱.雄安新区的岩石圈有效弹性厚度大约为15 km,均衡调整初始加载比为0.5~0.6,垂向构造应力为15~20 MPa,岩石圈参数对应的地震活动性较强,相关结果对于新区建设具有一定参考价值.     

2015年新疆皮山MW6.4地震发震断层和滑动分布反演

本文基于Sentinel-1A卫星影像数据提取了2015年皮山M_W6.4地震的同震形变场, 震中北部以隆升为主, 最大抬升量为12.9 cm; 南部以沉降为主, 最大沉降量为5.5 cm。 采用基于单一断层滑动模型的多峰粒子群优化和蒙特卡罗算法, 以LOS向InSAR形变场为约束, 对发震断层的几何模型进行非线性反演。 在此基础上, 联合InSAR和GPS数据, 利用最速下降法反演断层滑动分布。 综合结果表明: 发震断层是顶部埋深约7.4 km的隐伏断裂, 断层面大小为48 km×35 km, 断层走向、 倾角、 断层滑动角分别为111°、 19°、 91°; 断层最大滑动量0.47 m, 位于深度为10.6 km的区域; 累计地震矩3.89×10¹⁸ N·m, 约合矩震级M_W6.33。 最后, 依据主震断层滑移量计算了主震对周围中小断裂的库仑应力扰动变化, 结果显示距离震中最近的泽普断裂受主震影响的库仑应力明显增加; 震后3年内余震集中分布在泽普断裂库仑应力增加区域, 表明皮山地震主震对余震的发生可能具有一定的应力触发作用。     

城市生活固体废弃物处置规划和场地选址方向探讨

城市生活固体废弃物已成为重要环境污染问题之一,地质环境工作应为废弃物的填埋选址,防治污染提供服务。北京地质环境部门受北京市主管部门委托开展了全市生活固体废弃物填埋场地适宜性区划,卫生填埋场地环境地质影响评价,其成果已为市规划、环境行政部门所利用。     

中国-中亚-西亚经济走廊贸易投资便利化水平研究

立足“一带一路”倡议总体规划和最终目标,运用主成分分析法,对中国-中亚-西亚经济走廊国家的贸易投资便利化水平进行测度,并依据其贸易投资便利化得分,将沿廊17国划分为风险区、谨慎区、便利区、畅通区四个等级。在此基础上,将中国-中亚-西亚经济走廊划分为三大廊段,并对其贸易投资相关的条件进行详细分析,为出境企业和机构更好地了解沿廊国家贸易投资便利化、参与沿廊经济建设、防范经贸合作风险,推进“一带一路”建设提供参考依据。     

Nearshore scavenging phenomenon elucidated by <Superscript>234</Superscript>th/<Superscript>238</Superscript>u disequilibrium in the coastal waters off Western Taiwan

Dissolved and particulate ²³⁴Th activities in surface seawater were determined at 27 stations along the coastline of western Taiwan during 19–23 November 2004. Contrasting scavenging settings were observed between the northern and southern regimes of the nearshore water off western Taiwan, separated by the Cho-Shui River. The northern regime is characterized by a large quantity of suspended load contributed by northward transport of a suspension plume from the Cho-Shui River, while the southern regime, low in suspended load and high in chlorophyll concentration, is a system controlled by biological activity. A scavenging model that takes account of the physical transport was used to estimate the ²³⁴Th budget in order to estimate the scavenging and removal rates from the nearshore water. The scavenging and removal rates ranged from 21 to 127 dpm m⁻³d⁻¹ and from 36 to 525 dpm m⁻³d⁻¹, for dissolved and particulate ²³⁴Th, respectively. The removal fluxes of particulate organic carbon (POC) and particulate organic nitrogen (PON) were estimated by multiplying the particulate ²³⁴Th removal flux to the organic carbon/²³⁴Th and nitrogen/²³⁴Th ratios in suspended particles, which ranged from 4.5 to 275.2 mmol-C m⁻²d⁻¹ and from 1.3 to 50.1 mmol-N m⁻²d⁻¹, respectively. These fluxes resulted in residence times of 1∼20 days for the POC in the surface water of nearshore water off western Taiwan.     

Tyrosinase, a new innate humoral immune parameter in large yellow croaker （Pseudosciaena crocea R）

We evaluated the immune response to infection with a pathogen in large yellow croaker(Pseudosciaena crocea Richardson).The fish were given an intraperitoneal(i.p.) injection of Vibrio parahaemolyticus or sterile sea water(control).We collected blood sera from the fish 0.17,1,2,4,8,12,or 16 d after injection(dpi).We measured tyrosinase activity and the concentrations of lysozyme,NOS,and antibodies.Serum tyrosinase activity was significantly higher at 0.17 and 4 dpi than in the control group,and peaked at 8 d...