环塔里木盆地绿洲城市发展与水环境质量协调度

解决好新疆环塔里木盆地绿洲城市发展与水环境质量之间的关系,对"一带一路"倡议顺利实施及新疆社会稳定具有十分重要的作用。基于2004-2017年环塔里木盆地绿洲城市发展与水环境变化状况,构建城市发展与水环境质量的综合评价模型及二者的协调度模型,以探讨环塔里木盆地绿洲城市发展、水环境质量变化及二者的协调关系。结果表明：2004-2017年,（1）环塔里木盆地绿洲城市发展综合指数呈现出逐年稳定上升的趋势,经济发展和城镇空间规模扩大是环塔里木盆地绿洲城市发展的主要形式;（2）环塔里木盆地绿洲城市的水环境质量综合指数呈现出逐年降低的趋势,水环境质量形势严峻;（3）环塔里木盆地绿洲城市发展-水环境质量系统的协调度呈现倒U型的稳定发展趋势,但总体上两者的协调度较低,城市发展和水环境质量之间的矛盾日益突出。     

水资源约束下的河西走廊城市经济脆弱性时空演变及其影响因素

城市经济脆弱性作为当前脆弱性研究中的重要领域,为人-地系统耦合研究提供了新的视角,并为城市可持续健康发展提供有益的决策支持和管理方法。依据城市经济脆弱性内涵,基于暴露度、敏感性、适应能力构建了城市经济脆弱性评价指标体系,运用熵权TOPSIS法评价河西走廊地区及区域内五市的城市经济脆弱性,并采用障碍度模型识别影响区域城市经济脆弱性变化的因素。结果显示：（1）2006—2015年,河西走廊地区城市经济脆弱性呈现出先曲折下降（2006—2011年）再波动上升趋势（2012—2015年）;（2）河西走廊地区的城市经济脆弱性具有明显的空间特征,经历了东西高、中部低到整体较高的演变过程;（3）阻碍河西走廊地区城市经济脆弱性降低的障碍因子由适应能力逐步转变为暴露度。针对河西走廊地区各市主要障碍因子,提出针对性优化措施。     

Glacier changes in the eastern Nyainqêntanglha Range of Tibetan Plateau from 1975 to 2013

Maritime-type glaciers in the eastern Nyainqêntanglha Range, located in the southeastern part of the Tibetan Plateau, are an important water source for downstream residents and ecological systems. To better understand the variability of glaciers in this region, we used the band ratio threshold(TM3/TM5 for the Landsat TM /ETM+ and TM4/TM6 for Landsat OLI) to extract glacier outlines in ~1999 and ~2013. After that, we also generated a series of glacier boundaries and monitored glacier variations in the past 40 years with the help of the Chinese Glacier Inventory data(1975) and Landsat TM, ETM+ and OLI data. The total glacier area decreased by 37.69 ± 2.84% from 1975 to 2013. The annual percentage area change(APAC) was ~1.32% a-1 and ~1.29% a-1 in the periods 1975-1999 and 1999-2013, respectively. According to the lag theory, the reaction time is probably about 10 years and we discuss the variations of temperature and precipitation between 1965 and 2011. Temperature and precipitation increased between 1965 and 2011 at a rate of 0.34°C /10 a and 15.4 mm/10 a, respectively. Extensive meteorological data show that the glacier shrinkage rate over the period may be mainly due to increasing air temperature, while the increasing precipitation partly made up for the mass loss of glacier ice resulting from increasing temperature may also lead to the low APAC between 1999 and 2013. The lag theory suggests that glacier shrinkage may accelerate in the next 10 years. Small glaciers were more sensitive to climate change, and there was a normal distribution between glacier area and elevation. Glaciers shrank in all aspects, and south aspects diminished faster than others.     

Layered farming for Marsupenaeus japonicus Bate

Marsupenaeusjaponicus Bate is one of the most valuable cultured shrimp species in China and outdoor earthen pond farming is the most common method of culturing this organism. The need to increase soil usage efficiency in aquaculture has been recognized and a great deal of research effort has been directed toward development of super-intensive farming systems. However, current research and development in this field is largely devoted to Litopenaeus vannamei Boone, while to M.japonicus Bate it has been neglected. In this study, a layered fanning system was designed and a 66-day study was conducted in M.japonicus Bate culture. The system comprised bracket and sand layers that divided a shrimp tank filled to a depth of 1.2 m into four water layers. Conventional tank culture （unlayered） was used as a control. The results show that survival rate, feed conversion efficiency and production of M.japonicus Bate in the layered farming system were 68%, 18%, and 0.59 kg/m^2, respectively, all of which are significantly higher than in the unlayered fanning system （P〈0.01）. These findings confirmed the possibility of using a layered system to culture M. japonicus Bate.     

��������ϵ��GNSS�����������ת�������о�

??GNSS??????????У??轫GNSS?????????????????????????????????????????GNSS???????????????????????????????????????????????????????????????????????????????????????????????????????????????е???????????????????????е????λ???ó????????????????????????????????????????????????????????????????о???GNSS????????????????????????????????????????????????????????????????????????????????????????????????????????????     

Biogeochemical records of paleoenvironmental changes in Nainital Lake,Kumaun Himalayas,India

Rapid urbanization and increased tourism around Nainital Lake in the Kumaun Himalayan region in north India has raised concerns about sediment and water pollution. Lead-210 dated sediment cores from the lake represent ~95 years of accumulation and yield a mean sedimentation rate of ~4.7 mm year⁻¹. Total organic carbon (TOC), percent N and S and their atomic C/N and C/S ratios, stable isotopes (δ¹³C, δ¹⁵N, and δ³⁴S), and specific biomarkers (n-alkanes and pigments) were measured in the core. Organic matter is primarily derived from in-lake algal production and TOC flux varies from 1.0 to 3.5 g m⁻² year⁻¹. Sediments are anoxic (Eh −328 to −187 mV) and have low (0.10–0.30 g m⁻² year⁻¹) N, but high (0.37–1.0 g m⁻² year⁻¹) S flux. Shifts in δ¹³C, δ¹⁵N, and δ³⁴S suggest in-lake microbial processes dominated by denitrification and sulfate reduction. The sediments are dominated by short-chain hydrocarbons with low Carbon Preference Index values. The pigments indicate a gradual shift to cyanobacterial domination of the phytoplankton community in recent years. Despite an increase in external input of nutrients, the trophic state of the lake has remained largely unchanged, and the perceived human-induced impacts are limited.     

Stress Responses to Rapid Temperature Changes of the Juvenile Sea Cucumber （Apostichopusjaponicus Selenka）

Activities of hexokinase （HK）, pyruvate kinase （PK）, superoxide dismutase （SOD） and catalase （CAT） and Hsp70 level were measured to evaluate the response of the commercially important sea cucumber （Apostichopus japonicus Selenka） to rapid temperature changes in laboratory. Animals were subjected to a higher temperature （from 10 to 20℃） （Tinc treatment） or to a lower temperature （from 20 to 10℃） （Tddec treatment） for 72 h. At 1, 3, 12, 24, 72 h of exposure, animals were removed and prepared for further analysis. Results showed that the effect of acute temperature changes on enzyme activities was significant. In Tinc treatment, activities of SOD and CAT increased immediately. The significant enhancement of SOD and CAT activities suggested that oxidative stress increases significantly when ambient temperature increasing from 10 to 20℃. The up-regulation of Flsp70 in Tinc and Tdec treatments indicated that Hsp70 was a bioindicator of thermal stress in the sea cucumber, and the expression pattern depended on the thermal treatment.     

频率域全波形反演方法研究进展

全波形反演是一种利用地震波传播的动力学特征来获取地下介质物性参数的反演方法,可为揭示地下精细结构提供重要依据。本文以弹性波方程作为数学模型来模拟地震波传播规律并进行相应的反演方法研究。为提高计算效率与反演结果的准确性,可将近似解析离散化（NAD）算子用于频率域弹性波方程的正演模拟。本文在频率域NAD离散的基础上推导阻抗矩阵的稀疏分块结构与反演目标函数对模型参数的梯度计算公式,由此建立基于NAD算子的频率域弹性波全波形反演方法。为验证该方法的有效性,文中通过数值实验对多种典型介质模型进行反演计算,均得到了理想的反演结果。

     

Geochemical reconstruction of late Holocene drainage and mixing in Kluane Lake,Yukon Territory

The level of Kluane Lake in southwest Yukon Territory, Canada, has fluctuated tens of metres during the late Holocene. Contributions of sediment from different watersheds in the basin over the past 5,000 years were inferred from the elemental geochemistry of Kluane Lake sediment cores. Elements associated with organic material and oxyhydroxides were used to reconstruct redox fluctuations in the hypolimnion of the lake. The data reveal complex relationships between climate and river discharge during the late Holocene. A period of influx of Duke River sediment coincides with a relatively warm climate around 1,300 years BP. Discharge of Slims River into Kluane Lake occurred when Kaskawulsh Glacier advanced to the present drainage divide separating flow to the Pacific Ocean via Kaskawulsh and Alsek rivers from flow to Bering Sea via tributaries of Yukon River. During periods when neither Duke nor Slims river discharged into Kluane Lake, the level of the lake was low and stable thermal stratification developed, with anoxic and eventually euxinic conditions in the hypolimnion.     

Simulation and projection of climate change using CMIP6 Muti-models in the Belt and Road Region

Climate condition over a region is mostly determined by the changes in precipitation, temperature and evaporation as the key climate variables. The countries belong to the Belt and Road region are subjected to face strong changes in future climate. In this paper, we used five global climate models from the latest Sixth Phase of Coupled Model Intercomparison Project (CMIP6) to evaluate future climate changes under seven combined scenarios of the Shared Socioeconomic Pathways and the Representative Concentration Pathways (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP4-3.4, SSP4-6.0 and SSP5-8.5) across the Belt and Road region. This study focuses on undertaking a climate change assessment in terms of future changes in precipitation, air temperature and actual evaporation for the three distinct periods as near-term period (2021-2040), mid-term period (2041-2060) and long-term period (2081-2100). To discern spatial structure, K?ppen-Geiger Climate Classification method has been used in this study. In relative terms, the results indicate an evidence of increasing tendency in all the studied variables, where significant changes are anticipated mostly in the long-term period. In addition to, though it is projected to increase under all the SSP-RCP scenarios, greater increases will be happened under higher emission scenarios (SSP5-8.5 and SSP3-7.0). For temperature, robust increases in annual mean temperature is found to be 5.2 °C under SSP3-7.0, and highest 7.0 °C under SSP5-8.5 scenario relative to present day. The northern part especially Cold and Polar region will be even more warmer (+6.1 °C) in the long-term (2081-2100) period under SSP5-8.5. Similarly, at the end of the twenty-first century, annual mean precipitation is inclined to increase largely with a rate of 2.1% and 2.8% per decade under SSP3-7.0 and SSP5-8.5 respectively. Spatial distribution demonstrates that the largest precipitation increases are to be pronounced in the Polar and Arid regions. Precipitation is projected to increase with response to increasing warming most of the regions. Finally, the actual evaporation is projected to increase significantly with rate of 20.3% under SSP3-7.0 and greatest 27.0% for SSP5-8.5 by the end of the century. It is important to note that the changes in evaporation respond to global mean temperature rise consistently in terms of similar spatial pattern for all the scenarios where stronger increase found in the Cold and Polar regions. The increase in precipitation is overruled by enhanced evaporation over the region. However, this study reveals that the CMIP6 models can simulate temperature better than precipitation over the Belt and Road region. Findings of this study could be the reliable basis for initiating policies against further climate induced impacts in the regional scale.