Surface heat budget and solar radiation allocation at a melt pond during summer in the central Arctic Ocean

The heat budget of a melt pond surface and the solar radiation allocation at the melt pond are studied using the 2010 Chinese National Arctic Research Expedition data collected in the central Arctic. Temperature at a melt pond surface is proportional to the air temperature above it. However, the linear relationship between the two varies, depending on whether the air temperature is higher or lower than 0℃. The melt pond surface temperature is strongly influenced by the air temperature when the latter is lower than 0℃. Both net longwave radiation and turbulent heat flux can cause energy loss in a melt pond, but the loss by the latter is larger than that by the former. The turbulent heat flux is more than twice the net longwave radiation when the air temperature is lower than 0℃. More than 50% of the radiation energy entering the pond surface is absorbed by pond water. Very thin ice sheet on the pond surface(black ice) appears when the air temperature is lower than 0℃; on the other hand, only a small percentage(5.5%) of net longwave in the solar radiation is absorbed by such a thin ice sheet.     

Early Cambrian epibolic gastrulation: A perspective from the Kuanchuanpu Member, Dengying Formation, Ningqiang, Shaanxi, South China

The Cambrian explosion is marked by the apparent sudden appearance of diverse metazoan skeletal fossils and an increase in the complexity of both body and trace fossils. Among them, fossil eggs and embryos from the Lower Cambrian Kuanchuanpu Member of the Dengying Formation at Ningqiang in southern China provide a unique window for investigating the ontogeny of metazoans. Gastrulation is the cell migration stage after cleavage, and can be viewed as the embryonic analog of the transition from protozoan to metazoan grades of complexity. As an example, the embryonic developmental sequences of Punctatus emeiensis is well-documented because of the stellate spines covering the body surface, that are shared with embryonic stages represented by Olivooides and their growth stages represented by P. emeiensis. Although Olivooides was considered to be a taxonomic mixture, consideration of its variation was neglected. A specific type of embryo with zigzag blastopore lips that differs from typical candidate embryos for P. emeiensis is identified; its gastrulation process is reconstructed and is comparable to the epibolic gastrulation of extant metazoans. Both the embryos and adults of this ‘type’ display radial symmetry, that suggests an affinity distinct from that of echinoderms. Moreover, the body plan of penta-radial symmetry seen widely in Early Cambrian ‘Small Shelly Fossils’ (SSF's) was probably deep rooted in the Ediacaran.     

Quantitative simulation on soil moisture contents of two typical vegetation communities in Sanjiang Plain,China

Different types of vegetation occupy different geomorphology and water gradient environments in the San-jiang Plain,indicating that the soil moisture dynamics and water balance patterns of the different vegetation communi-ties might differ from each other.In this paper,a lowland system,perpendicular to the Nongjiang River in the Honghe National Nature Reserve(HNNR),was selected as the study area.The area was occupied by the non-wetland plant forest and the typical wetland plant meadow.The Microsoft Windows-based finite element analysis software package for simulating water,heat,and solute transport in variably saturated porous media(HYDRUS),which can quantita-tively simulate water,heat,and/or solute movement in variably-saturated porous media,was used to simulate soil moisture dynamics in the root zone(20-40 cm) of those two plant communities during the growing season in 2005.The simulation results for soil moisture were in a good agreement with measured data,with the coefficient of determi-nation(R2) of 0.44-0.69 and root mean square error(RMSE) ranging between 0.0291 cm3/cm3 and 0.0457 cm3/cm3,and index of agreement(d) being from 0.612 to 0.968.During the study period,the volumetric soil moisture content of meadow increased with the depth and its coefficient of variation decreased with the depth(from 20 cm to 40 cm),while under the forest the soil moisture content at different depths varied irregularly.The calculated result of water budget showed that the water budget deficit of the meadow was higher than that of the forest,suggesting that the meadow is more likely to suffer from water stress than the forest.The quantitative simulation by HYDRUS in this study did not take surface runoff and plant growth processes into account.Improved root water uptake and surface runoff models will be needed for higher accuracy in further researches.     

Spatial distribution of Ice Shelf Water in front of the Amery Ice Shelf,Antarctica in summer

As a unique low-temperature water mass in Antarctic coastal region, the Ice Shelf Water (ISW) is an important component for the formation of the Antarctic Bottom Water (AABW). In this paper, we present a criterion for ISW identification based on freezing point at the sea surface, and we study spatial distribution of ISW in front of the Amery Ice Shelf (AIS) and its flow path in Prydz Bay by analyzing hydrographic data from Australian cruises in 2001 and 2002, as well as Chinese cruises in 2003, 2005, 2006, and 2008, all being made in the austral summer. The relatively cold and fresh ISW occurred as several discrete water blocks with cold cores in front of the AIS, within the depth range of 100?600 m, under the seasonal thermocline. ISW had obvious temporal and spatial variations and the spatial distribution pattern changed greatly after 2005. Most of ISW was concentrated west of 73°E during 2001 to 2003 and 2006, but it was widespread to east in 2005 and 2008. In all observation years, a small amount of cold ISW always occurs at the west end of the AIS front section, where the coldest ISW in the whole section also occurred in 2001, 2003 and 2006. Considering general cyclonic circulation pattern under the AIS, the ISW flowing out from west end of the AIS front might have experienced the longest cooling period under ice shelf, so it would have the lowest temperature. Analysis of data from meridian sections in Prydz Bay in 2003 implied that ISW in the west could spread north to the continental break along the east flank of the Fram Bank near 70.5°E, mix with the upwelling Circumpolar Deep Water and possibly contribute to the formation of AABW.     

改革开放以来中国省际边缘区研究历程及展望

省际边缘区由于自身的优势和劣势,在区域经济格局中,既面临着新的发展机遇,又面临着被边缘化的危险,成为统筹发展的热点区域。在对1978年以来各个时期代表性的省际边缘区研究成果进行梳理、归纳和分析的基础上,结合社会经济发展的阶段特征和不同时期研究的价值取向,认为我国省际边缘区的研究历程经历了问题导向型、理论导向型和功能导向型3个研究阶段,并对研究内容和现状进行了述评。结合当前省际边缘区发展所面临的新问题,对未来研究方向进行了展望。     

藏北羌塘中部存在志留纪洋盆——来自桃形湖蛇绿岩中斜长花岗岩的锆石U-Pb年龄证据

报道了羌塘西部桃形湖蛇绿岩中斜长花岗岩的锆石U-Pb定年结果和岩石地球化学资料及锆石Hf同位素成分。斜长花岗岩中的锆石具有典型的岩浆生长环带,结合其Th/U值(0.16~0.44),表明为典型的岩浆成因。锆石LA-ICP-MS和Cameca U-Pb定年结果分别为441Ma±2Ma和442Ma±3Ma,相当于早志留世,略年轻于伴生的堆晶辉长岩。锆石的εHf(t)值为+8.13~+11.23,平均值为+9.50,具有明显的幔源成因特征。全岩地球化学分析结果表明,斜长花岗岩是洋壳运移过程辉长岩部分熔融形成的。斜长花岗岩的年龄数据表明,羌塘中部地区存在志留纪洋盆。     

北京地区超大深基坑工程设计与施工实践

基坑工程是地下空间开发的技术支撑,随着人们对地下空间开发的需要,基坑工程正面临新的挑战。回顾了北京地区浅层基坑的特点及设计思路;重点分析了目前城市超大深基坑的特点及挑战;结合北京市某超大深基坑工程设计施工实践及其监测评价,总结了城市超大深基坑工程实践中的设计概念;就北京地区城市基坑的发展提出了新的设想。     

Changes in carbon sink value based on RS and GIS in the Heidaigou opencast coal mine

The dynamic change in the carbon sink value of the Heidaigou opencast mining area in the Inner Mongolia Autonomous Region of China was analyzed by remote sensing and geographical information system to investigate the effect of land rehabilitation and ecological reconstruction in mining area on the biogeochemical cycle of carbon. The mining area’s carbon sink volume and value from 1987 to 2010 were calculated according to carbon sink capacity differences across various vegetation and land use types. The results indicate the following conclusions. (1) The carbon sink volume and value decreased by 17 % over 23 years, from 7,217,104.59 t and $1,082.57 million to 5,990,016.2 t and $898.50 million, respectively. (2) Assuming a dump is rehabilitated with 20 % woodland and 80 % grassland, the carbon sink volume and value can increase to 6,593,952.5 t and $989.09 million, respectively. The value would increase by 10.08 % after land rehabilitation. (3) Assuming that other industrial land is rehabilitated with grassland after the dumps are completely rehabilitated, the carbon sink volume and value would increase to 6,742,684.36 t and $1011.40 million, respectively. The value would increase by 12.57 % after land rehabilitation. The results indicate that land rehabilitation and ecological reconstruction can increase mining area carbon sinks and produce ecological and economic benefits. This study provides a new perspective on land rehabilitation and ecological reconstruction.     

中亚五国自华进口贸易技术溢出及碳排放影响研究

梳理1992—2018年中亚五国碳排放变化过程,运用碳排放库兹涅茨曲线模拟人均碳排放与人均国内生产总值（GDP）的关系,基于中亚五国人均GDP、工业增加值、研发投入、自华进口中间品和资本品的技术溢出存量等指标,构建面板数据固定效应模型以探究碳排放影响机制。结果表明：（1） 中亚五国碳排放先降后升,各国碳排放的变化率波动较大,其中哈萨克斯坦碳排放占中亚五国碳排放比重最大。（2） 就人均碳排放与人均GDP拟合的碳排放库兹涅茨曲线关系而言,哈萨克斯坦和土库曼斯坦表现为倒N型,乌兹别克斯坦、塔吉克斯坦、吉尔吉斯斯坦和中亚五国表现为N型。（3） 中亚五国自华进口额呈现较快的增长趋势,其中自华进口的中间品和资本品合计约占自华进口总额的3.920%~10.976%,中亚五国整体及各国中间品技术溢出存量均明显大于资本品技术溢出存量。（4） 在影响中亚五国碳排放的诸多因素中,人均GDP和工业增加值占GDP比重的回归系数显著为正,人均GDP、工业增加值占GDP比重每上升1%,碳排放分别增加0.337%和0.343%,研发投入、交互项LnZJ_it×LnS_it（中间品技术溢出存量的自然对数×工业增加值占GDP比重的自然对数）的回归系数显著为负,研发投入每增加1%,碳排放可减少约0.432%,在降低因工业增加值占GDP比重上升导致的碳排放方面,中间品技术溢出存量的影响极小。