GPS time-series and its response to <Emphasis Type="Italic">M</Emphasis><Subscript>S</Subscript>=8.1 Kunlunshan earthquake

In this paper, observation data in 25 GPS reference stations of China have been analyzed by calculating GPS position coordinate time-series with GIPSY. Result shows there is an obvious trend variation in such time-series. The trend variations of time series along the longitude and latitude coordinate reflect the motion of each position in the global-plate, in which the trend variation in the vertical direction reveals some large-scale construction information or reflects the local movement around the positions. The analysis also shows that such time-series have a variation cycle of nearly 1.02 a, but the reason still remains to be further studied. At the end of this paper, response of the time-series of M _S=8.1 Kunlunshan earthquake was analyzed, and the seismogenic process of M _S=8.1 Kunlunshan earthquake, according to the time proceeding and the feature of anomaly, was divided into 3 phases—changes in blocks with forces, strain accumulation, quick accumulation and slow release of energy. At the initial stage of seismogenic process of M _S=8.1 earthquake and at the imminent earthquake, coseismic process as well as during the post earthquake recovery, anomaly in vertical direction is always in a majority. The anomalous movement in vertical direction at the initial stage resulted in a blocking between faults, while at the middle stage of seismogenic process, the differential movement between blocks are in a majority, which is the major reason causing energy accumulating at the blocking stage of faults.     

三峡截流以来长江洪季潮区界变动河段冲刷地貌

潮区界河段河势演变对三峡工程的响应是长江经济带建设中的重要问题。然而受观测手段所限,对三峡截流以来潮区界变动范围及其地貌演变的客观认识亟待探讨。对大通站洪季水位资料进行频谱分析,初步判断了近期长江洪季潮区界位置;对比1998年和2013年水下地形资料,分析了三峡大坝截流以来该河段河槽的冲淤演变特征;利用多波束测深系统对冲刷明显河段的微地貌进行了高分辨率观测。结果显示:（1）1998-2013年潮区界变动河段河槽整体冲刷5 649.7万m3。其中,上段全面冲刷,太白、太阳两洲并岸,铜陵沙被冲开,主槽刷深达5.6 m;中段主泓摆动,天然洲南冲北淤,黑沙洲中水道淤死,南水道左岸最大冲深达8.9 m;下段近岸冲刷强烈,北岸最大冲深达15.4 m;（2）该河段近期处于剧烈的冲刷环境,左岸冲刷尤为显著;（3）冲刷深槽分布在顺直河段,深达5.4~12.6 m;冲刷坑分布在分汊河段平面形态突变处,最大冲深达28.1~30.5 m;水下侵蚀陡坡分布在近岸侵蚀严重的顺直河段,坡度为0.59~0.62。     

The Data Depth-weight-kernel Estimation of the Model Error of Satellite Orbit Determination

It is an objective fact that there exists error in the satellite dynamic model and it will be transferred to satellite orbit determination algorithm, forming a part of the connotative model error. Mixed with the systematic error and random error of the measurements, they form the unitive model error and badly restrict the precision of the orbit determination. We deduce in detail the equations of orbit improvement for a system with dynamic model error, construct the parametric model for the explicit part of the model and nonparametric model for the error that can not be explicitly described. We also construct the partially linear orbit determination model, estimate and fit the model error using a two-stage estimation and a kernel function estimation, and finally make the corresponding compensation in the orbit determination. Beginning from the data depth theory, a data depth weight kernel estimator for model error is proposed for the sake of promoting the steadiness of model error estimation. Simulation experiments of SBSS are performed. The results show clearly that the model error is one of the most important effects that will influence the precision of the orbit determination. The kernel function method can effectively estimate the model error, with the window width as a major restrict parameter. A data depth-weight-kernel estimation, however, can improve largely the robustness of the kernel function and therefore improve the precision of orbit determination.     

近年我国区域水文研究的若干进展

我国区域水文学的研究是在解放后其正发展起来的。尽管迄今人们对区域水文学仍有不同的认识,例如区域水文学是否可以与水文地理学等同,或是区域水文学是否应隶属于区域地理学等等,但是作为水文学的分支学科是无疑的。区域水文学从整体的观点来研究区域水文情势。区城可以是功能区,如城市、出口加工中心区等,或为自然景观区,如干旱区、喀斯特区等,也可以是行政区。目前,许多水文水利工作者已在致力于区域水文学的研究。     

NGC 7538—IRS1致密HⅡ区研究

本文在分析研究NGC7538-IRS1致密HⅡ区H_2CO和OH脉泽辐射VLBI观测结果的基础上,指出该HⅡ区合理的模型是:HⅡ区表面为厚的尘埃层包围,尘埃层两极已被突破,并形成双极流;HⅡ区外面有一个环形转动气体-尘埃云,存在由环向HⅡ区表面的物质下落;包括环和HⅡ区在内的整个系统视向速度为-61km/s,该系统居于视向速度为-57km/s的更大分子云中。H_2CO和OH脉泽发生在HⅡ区两极附近离HⅡ区表面小于0.2R_(HⅡ)的区域内。利用上述模型,还讨论了H_2O脉泽及其他分子吸收线和发射线的发生区域。     

中国东部海域大气气溶胶入海通量的研究

根据中国东部海域气溶胶浓度及分级采样资料,计算得出黄海、东海及日本以南海域沙尘气溶胶的代表元素铝(Al)每月干沉降通量分别为42.8、18.3、5.2mg/m2;其中各海域春季的干沉降通量均占全年干沉降通量的40%以上.相应每月总沉降通量分别为54.1、29.8、10.5mg/m2.渤海、黄海、东海及日本以南海域每年沙尘气溶胶总沉降通量分别为26.4、9.3、5.1、1.8g/m2.东海污染元素总沉降通量以春季最大,夏、秋季次之,冬季最小.日本以南海域锑(Sb)元素总沉降通量的季节分布为冬季最大,夏、秋季次之,秋季最小;硒(Se)元素总沉降通量的最大值出现在夏季,其他季节分布比较均匀.     

Geophysical investigations of crust-scale structural model of the Qiongdongnan Basin, Northern South China Sea

Rifting of the Qiongdongnan Basin was initiated in the Cenozoic above a pre-Cenozoic basement, which was overprinted by extensional tectonics and soon after the basin became part of the rifted passive continental margin of the South China Sea. We have integrated available grids of sedimentary horizons, wells, seismic reflection data, and the observed gravity field into the first crust-scale structural model of the Qiongdongnan Basin. Many characteristics of this model reflect the tectonostratigraphic history of the basin. The structure and isopach maps of the basin allow us to reconstruct the history of the basin comprising: (a) The sediments of central depression are about 10 km thicker than on the northern and southern sides; (b) The sediments in the western part of the basin are about 6 km thicker than that in the eastern part; (c) a dominant structural trend of gradually shifting depocentres from the Paleogene sequence (45–23.3 Ma) to the Neogene to Quaternary sequence (23.3 Ma–present) towards the west or southwest. The present-day configuration of the basin reveals that the Cenozoic sediments are thinner towards the east. By integrating several reflection seismic profiles, interval velocity and performing gravity modeling, we model the sub-sedimentary basement of the Qiongdongnan Basin. There are about 2–4 km thick high-velocity bodies horizontal extended for a about 40–70 km in the lower crust (v > 7.0 km/s) and most probably these are underplated to the lower stretched continental crust during the final rifting and early spreading phase. The crystalline continental crust spans from the weakly stretched domains (about 25 km thick) near the continental shelf to the extremely thinned domains (<2.8 km) in the central depression, representing the continental margin rifting process in the Qiongdongnan Basin. Our crust-scale structural model shows that the thinnest crystalline crust (<3 km) is found in the Changchang Sag located in the east of the basin, and the relatively thinner crystalline crust (<3.5 km) is in the Ledong Lingshui Sag in the west of the basin. The distribution of crustal extension factor β show that β in central depression is higher (>7.0), while that on northern and southern sides is lower (<3.0). This model can illuminate future numerical simulations, including the reconstruction of the evolutionary processes from the rifted basin to the passive margin and the evolution of the thermal field of the basin.     

海洋中铁的来源、形态和对初级生产力的限制作用

在海洋中,铁和Ｎ、Ｐ等主营养盐一样,也是一种限制浮游植物初级生产力的重要因素。由于铁是一种化学活性较高的元素,所以海水中铁的存在形态、来源及沉降会直接影响其生物可利用性。目前人们一般采用预富集／原子吸收法（ＡＡＳ）或是借助于电分析技术（如催化极谱）来测定海水中的铁。     

Effects of grazing and climate change on species diversity in sandy grassland, Inner Mongolia, China

To understand the effects of animal grazing activities and climate change on sandy grassland vegetation in northern China, a field grazing and protected enclosure experiment was conducted from 1992 through 2006 in Horqin Sand Land, Inner Mongolia. The results showed that (1) the grazing was primary responsible for changes of the vegetation richness and diversity in the grazing grassland and that changing climate was the main reason for changes in the species richness and diversity in the grassland protected from grazing; (2) light and moderate grazing can promote restoration of the richness and the diversity in the degraded grassland, and heavy grazing could result in a decrease of the richness and diversity; (3) heavy grazing can result in significant decrease of the perennial diversity, and moderate and light grazing promotes increase of the perennial diversity; the grazing, whether heavy or moderate and light grazing, was beneficial to increase of the annual diversity; (4) heavy grazing was not beneficial to diversity of Graminean and Chenopodiaceae, and moderate and light grazing was favorable the diversity of Compositae and Chenopodiaceae; (5) the warm-humid climate was favorable to increase of the richness and the diversity, and the warm-drought climate could result in decease of the richness and the diversity; (6) increased precipitation was favorable to perennial diversity and the diversity of Graminean, Leguminosae, and Compositae, and decreased precipitation had few effects on the annual diversity and Chenopodiaceae diversity.     

微塑料添加对小麦苗期生长及干物质分配的影响

土壤环境中微塑料污染已成为全球关注的环境问题。关于微塑料对于植物生长的直接影响和由于土壤理化性状改变的间接影响研究已逐步开展,但针对小麦的研究鲜见报道。试验选择两个旱地小麦品种(甘春27和禾尚头)作为研究对象,选取高密度聚乙烯作为微塑料添加,设置3种质量浓度(0、1、4 g·kg^-1)开展盆栽试验,对不同微塑料组合处理下小麦的出苗率、株高、全株生物量和地上/地下干物质分配进行了分析。结果表明：(1)微塑料添加对两个品种出苗率没有影响。(2)禾尚头在添加1 g·kg^-1微塑料时比添加0、4 g·kg^-1时全株生物量分别高46.7%、8.5%,甘春27在添加1 g·kg^-1微塑料时比添加0、4 g·kg^-1时全株生物量分别高28.7%、17.2%;甘春27整体比禾尚头在3种浓度处理下全株生物量分别高24.9%、9.6%、1.5%。(3)不同试验处理条件下,甘春27将更多的干物质分配在地上植株的构建,其在地下(根系)和地上(茎叶)部分的分配比例整体小于禾尚头。整体上,适度微塑料添加可...