DATABASE OF LANDSLIDES TRIGGERED BY 2015 GORKHA(NEPAL) MW7.8 EARTHQUAKE

In this study, a detailed database of landslides triggered by the 25 April 2015 Gorkha (Nepal)M_W7.8 earthquake is constructed based on visual interpretation of pre- and post-earthquake high-resolution satellite images and field reconnaissance. Results show the earthquake triggered at least 47 200 landslides, which have a NWW direction spatial distribution, similar with the location and strike of the seismogenic fault. The landslides are of a total area about 110km² and an oval distribution area about 35 700km². On the basis of a scale relationship between landslide area (A)and volume (V), V=1.314 7×A^{1.208 5}, the total volume of the coseismic landslides is estimated to be about 9.64×10⁸m³. In the oval landslide distribution area, the landslide number density, area density, and volume density were calculated and the results are 1.32km^-2, 0.31%, and 0.027m, respectively. This study provides a detailed and objective inventory of landslides triggered by the Gorkha earthquake, which provides very important and essential basic data for study of mechanics of coseismic landslides, spatial pattern, distribution law, and hazard assessment. In addition, the landslide database related to an individual earthquake also provides an important earthquake case in a subduction zone for studying landslides related to multiple earthquakes from a global perspective.     

考虑支座摩擦滑移及结构碰撞的非规则人字形桥梁地震响应分析

针对非规则人字形桥梁在地震作用下灾变严重的问题,以一座非规则人字形桥梁为研究对象,建立其空间分析模型,研究综合考虑支座摩擦滑移、结构碰撞对非规则人字形桥梁地震响应的影响。结果表明:邻梁间的碰撞作用可使得桥梁墩顶位移及内力相比不考虑时有所减小,但同时也使梁体产生了较大的加速度脉冲效应;当考虑支座摩擦滑移和结构碰撞时,固定墩墩顶位移和邻梁相对位移峰值有一定程度增大,然而对梁体加速度脉冲效应结果影响并无统一规律;纵向地震波作用下,非规则人字形桥梁不仅存在顺桥向的碰撞,横桥向的碰撞响应也不容忽视。非规则人字形桥梁进行抗震设计计算时应选取符合实际情况的计算模型,考虑支座摩擦滑移及结构间的碰撞。     

Carbon pools and fluxes in the China Seas and adjacent oceans

The China Seas include the South China Sea, East China Sea, Yellow Sea, and Bohai Sea. Located off the Northwestern Pacific margin, covering 4700000 km~2 from tropical to northern temperate zones, and including a variety of continental margins/basins and depths, the China Seas provide typical cases for carbon budget studies. The South China Sea being a deep basin and part of the Western Pacific Warm Pool is characterized by oceanic features; the East China Sea with a wide continental shelf, enormous terrestrial discharges and open margins to the West Pacific, is featured by strong cross-shelf materials transport; the Yellow Sea is featured by the confluence of cold and warm waters; and the Bohai Sea is a shallow semiclosed gulf with strong impacts of human activities. Three large rivers, the Yangtze River, Yellow River, and Pearl River, flow into the East China Sea, the Bohai Sea, and the South China Sea, respectively. The Kuroshio Current at the outer margin of the Chinese continental shelf is one of the two major western boundary currents of the world oceans and its strength and position directly affect the regional climate of China. These characteristics make the China Seas a typical case of marginal seas to study carbon storage and fluxes. This paper systematically analyzes the literature data on the carbon pools and fluxes of the Bohai Sea,Yellow Sea, East China Sea, and South China Sea, including different interfaces(land-sea, sea-air, sediment-water, and marginal sea-open ocean) and different ecosystems(mangroves, wetland, seagrass beds, macroalgae mariculture, coral reefs, euphotic zones, and water column). Among the four seas, the Bohai Sea and South China Sea are acting as CO_2 sources, releasing about0.22 and 13.86–33.60 Tg C yr~(-1) into the atmosphere, respectively, whereas the Yellow Sea and East China Sea are acting as carbon sinks, absorbing about 1.15 and 6.92–23.30 Tg C yr~(-1) of atmospheric CO_2, respectively. Overall, if only the CO_2 exchange at the sea-air interface is considered, the Chinese marginal seas appear to be a source of atmospheric CO_2, with a net release of 6.01–9.33 Tg C yr~(-1), mainly from the inputs of rivers and adjacent oceans. The riverine dissolved inorganic carbon (DIC) input into the Bohai Sea and Yellow Sea, East China Sea, and South China Sea are 5.04, 14.60, and 40.14 Tg C yr~(-1),respectively. The DIC input from adjacent oceans is as high as 144.81 Tg C yr~(-1), significantly exceeding the carbon released from the seas to the atmosphere. In terms of output, the depositional fluxes of organic carbon in the Bohai Sea, Yellow Sea, East China Sea, and South China Sea are 2.00, 3.60, 7.40, and 5.92 Tg C yr~(-1), respectively. The fluxes of organic carbon from the East China Sea and South China Sea to the adjacent oceans are 15.25–36.70 and 43.93 Tg C yr~(-1), respectively. The annual carbon storage of mangroves, wetlands, and seagrass in Chinese coastal waters is 0.36–1.75 Tg C yr~(-1), with a dissolved organic carbon(DOC) output from seagrass beds of up to 0.59 Tg C yr~(-1). Removable organic carbon flux by Chinese macroalgae mariculture account for 0.68 Tg C yr~(-1) and the associated POC depositional and DOC releasing fluxes are 0.14 and 0.82 Tg C yr~(-1), respectively. Thus, in total, the annual output of organic carbon, which is mainly DOC, in the China Seas is 81.72–104.56 Tg C yr~(-1). The DOC efflux from the East China Sea to the adjacent oceans is 15.00–35.00 Tg C yr~(-1). The DOC efflux from the South China Sea is 31.39 Tg C yr~(-1). Although the marginal China Seas seem to be a source of atmospheric CO_2 based on the CO_2 flux at the sea-air interface, the combined effects of the riverine input in the area, oceanic input, depositional export,and microbial carbon pump(DOC conversion and output) indicate that the China Seas represent an important carbon storage area.     

水产饲料添加剂--多糖肽对珍珠贝生长的影响

利用光度法测定法分别测定了水产饲料添加剂多糖肽(简称多糖肽)的氨基酸、多糖和维生素的含量;利用平行对照试验法,观察了多糖肽对珍珠贝生长发育的影响。实验结果表明,多糖肽的氨基酸、多糖和维生素含量分别为40％～48％,12％～19％和9％～10％;多糖肤具有显著促进合浦珠母贝(Pinctada functa Gould)后期幼虫、幼龄贝和大珠母贝(Pinctada maxima Jameson )幼龄贝生长发育的作用、同时能够提高大珠母贝幼龄贝的存活率。     

应用ADP探测长江口区泥沙浓度的实验研究

声学多普勒流速剖面仪ADP不仅可以测量流速,其记录的声强信号还包含有泥沙浓度的信息,为探讨ADP测悬沙浓度的可行性,本文根据长江口区现场六点法测得的悬沙浓度,对输出信号进行标定,反演获得悬沙浓度。结果表明在500kHz的工作频率下,计算出的悬沙浓度在中上层水体平均误差较小(25％～38％),但要用ADP测整个垂直剖面的悬沙浓度还有待做进一步试验研究。     

Study of chemical forms of phosphorus and their bioavailability in the sediments

Chemical forms of phosphorus in the sediments of the Daya Bay, the Zhujiang River estuary, and the Xiamen Bay are measured with extraction solutions of MgCl2, NaOH, and HCl. Their availabilities to Chlorella sp. and Isochrysis galbana are estimated by using sediments as the sole source of P in the bioassays. The results show that the contents of total phosphorus (TP) in these sediments are 449.3, 650.1 and 643.9 mg/kg, respectively. The contents of non-apatite inorganic P (NAIP) extracted with MgCl2 and NaOH from 3 sediments are 168.8, 146.6 and 118.1 mg/kg,respectively, and account for 18.3%～32.6% of TP. The phosphorus extracted with HCI solution is greater than that extracted with NaOH solution and the lowest extracted P is MgCl2-extractable P. The greatest relative growth rates of Chlorella sp. and Isochrysis galbana cultured with sediments are in the range of 4.3%～26.9%. The increasing biomasses of these algae correspond to NAIP and AAPP (the estimated algal-available particulate P). AAPP accounts for 42.4%～78.2% of NAIP, 21.1%～27.1% of total inorganic P, and 11.8%～20.3% of TP, respectively.     

Wave measurement based on light refraction

Some authors have developed a few methods of measuring wave slopes based on light refraction, including the measurement method via the distribution of light intensity or color under water. A new method based on light refraction is specified for the measurement of wave surface elevation in wave flume via imaging technology. A plane painted with black and white stripes is put on the flume floor as an indication plane, which can be arranged easily and cheaply. Compared with the previous methods, the present method is less sensitive to the noise and nonlinear effects of optical process, which can be taken as a digital method. The CCD camera is fixed above the flume with its optical axis arranged vertically to grab the images of stripes modulated by the wave surface. The modulated value can be calculated from the Hilbert transform, and then the wave surface elevation can be obtained. The algorithm and experimental procedure are specified in detail, and some experimental results are provided to show the validity of the present method.     

Wave measurement based on light refraction

Some authors have developed a few methods of measuring wave slopes based on light refraction, including the measurement method via the distribution of light intensity or color under water. A new method based on light refraction is specified for the measurement of wave surface elevation in wave flume via imaging technology. A plane painted with black and white stripes is put on the flume floor as an indication plane, which can be arranged easily and cheaply. Compared with the previous methods, the present method is less sensitive to the noise and nonlinear effects of optical process, which can be taken as a digital method. The CCD camera is fixed above the flume with its optical axis arranged vertically to grab the images of stripes modulated by the wave surface. The modulated value can be calculated from the Hilbert transform, and then the wave surface elevation can be obtained. The algorithm and experimental procedure are specified in detail, and some experimental results are provided to show the validity of the present method.     

答“评‘紫坪铺水库造成孔隙弹性耦合变化及其对2008年汶川地震触发作用’二维模拟的局限性”

程惠红等(2015)在"评‘紫坪铺水库造成孔隙弹性耦合变化及其对2008年汶川地震触发作用’二维模拟的局限性"一文中提出,陶玮等(2014)采用二维模型模拟紫坪铺水库造成孔隙弹性耦合变化是一个不足,夸大了汶川地震震源处库仑应力增长值.我们认为采用二维模型模拟水库造成汶川地震震源处库仑应力变化确实可能存在一定偏差,但不会如程惠红等认为的"与三维模型相比夸大三倍".这是因为在程惠红等引用的论证中,二维模型计算中选取了接近水库最大剖面宽度而不是水库平均剖面宽度作为加载量参数,造成计算得到震源处库仑应力明显夸大.此外,陶玮等(2014)提出论断的主要依据不是"震源处"库仑应力值的大小,而是紫坪铺水库蓄水"由浅入深影响到整条断层,尤其对浅层范围的加载作用明显,达上百千帕,为整个断层面的失稳提供了基础".初始破裂的发生既可能是由水库蓄水引起,也可能是并非水库蓄水造成的一次普通构造小震,但其发生引发断层面上部已被水库蓄水弱化部分的连锁失稳而发生大震.即汶川地震既可能为直接触发也可能为间接触发,而我们的研究结果认为地震的发生完全可能由间接触发产生.若仅纠结于"震源处"的库仑应力变化,则忽视了水库蓄水影响的主体.水库蓄水对地震触发作用是一个复杂问题,相对这一问题所涉及的一系列不确定性因素来说,二维模拟的局限性所造成的影响并不很大也不是最大的,也不妨碍我们据此得出紫坪铺水库蓄水促进汶川地震发生的结论.     

云贵川地区ZTD垂直剖面格网模型

利用ERA5大气再分析资料研究ZTD高程尺度因子的精细时间变化特征,构建顾及高程尺度因子精细时间变化的云贵川地区ZTD垂直剖面格网模型(YZTD-H模型)。以云贵川地区探空站分层ZTD数据作为参考值,检验YZTD-H模型的精度,并将其与GPT2w模型和GPT3模型进行比较。结果表明,顾及精细时间变化和垂直剖面变化的YZTD-H模型在时间维度和垂直剖面维度上均表现出较好的稳定性。