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71.
With the rise of low carbon economy and the deterioration of the international energy situation, most countries in the world pay more attention to energy issues. In this paper, based on a comparison with several countries of large energy consumption, we used long sequence statistics to analyze the energy consumption characteristics from the world and the history, including energy consumption, energy consumption structure and energy efficiency, and then summed up the characteristics of energy consumption in developed countries, analyzed China's energy consumption process and the current stage, and found out the main problems of energy consumption in China. At last, countermeasures for the healthy development of China's energy were proposed, including actively promoting scientific and technological progress, upgrading energy structure, developing low carbon economy, rationalizing energy prices, improving the proportion of clean energy consumption and emphasizing synergistic effect on environment protection.  相似文献   
72.
为了研究野生小黄鱼(Pseudosciaena polyactis)繁殖后代的形态性状对体质量的影响作用,以随机采集的729尾4.5月龄小黄鱼为研究对象,对每尾个体的体质量(g)和8个形态性状(cm):全长(X1)、体长(X2)、头长(X3)、躯干长(X4)、尾部长(X5)、尾柄长(X6)、尾柄高(X7)和体高(X8)进行准确测定,运用相关分析、多元回归分析和通径分析方法,分别计算性状间的相关系数、构建形态性状与体质量的多元回归方程,获得了通径系数和决定系数,进行了养殖小黄鱼的形态性状对体质量的影响研究。结果显示,8个形态性状与体质量的相关系数均达到极显著水平(P0.01);通径分析中,4个形态性状对体质量的通径系数达到极显著水平(P0.01),它们是影响体质量的重要指标,其中体长(通径系数:0.589)对体质量的直接影响最大。应用逐步多元回归分析建立了以体质量为因变量(Y),体长(X2)、躯干长(X4)、尾柄高(X7)和体高(X8)为自变量的回归方程:Y=–32.377+3.064X2–1.511X4+14.285X7+4.438X8。模型等式中形态性状与体质量的相关指数R2=0.927,说明所选性状是影响体质量的主要形态性状。以上分析结果为小黄鱼的选育测量指标的确定提供了理论依据。  相似文献   
73.
朱建荣  鲍道阳 《海洋学报》2016,38(12):11-22
河势是影响河口水动力和盐水入侵基本因子。本文利用20世纪50和70年代长江河口海图,数值化岸线和水深,结合2012年长江河口实测水深资料,分析长江河口自50年代以来的河势变化。长江河口为分汊河口,50年代仅为二级分汊,至70年代才形成三级分汊,四口入海的河势格局。70年代相比于50年代,北支淤浅严重,其上、中、下段容积变化分别为-64.13×106、-306.60×106和-639.27×106 m3,对应的变化率分别为-16.30%、-22.74%和-25.69%,均显著减小;南支的上、中、下段容积变化分别为-28.61×106、-35.69×106和126.43×106 m3,相应的变化率分别为-1.30%、-2.12%和4.36%;北港由于崇明浅滩和横沙浅滩的淤浅,下段容积明显减小,其上段和下段容积变化分别为109.21×106和-797.14×106 m3,对应的变化率分别为5.01%和-15.25%;南港上段由于河道淤浅容积减小,下段北由于铜沙浅滩被冲开形成北槽,导致水深变深、容积增加,其上段、下段北和下段南容积变化分别为-238.95×106、203.58×106和153.34×106 m3,对应的变化率分别为-8.96%、6.85%和3.26%。2012年相比于70年代,北支由于大量淤浅和围垦容积大幅减小,其上、中、下段容积变化分别为-199.06×106、-504.61×106和-654.12×106 m3,对应的变化率分别为-60.45%、-48.44%和-35.38%;南支的上、中、下段容积变化分别为92.34×106、193.01×106和-163.62×106 m3,相应的变化率分别为4.24%、11.73%和-5.40%;北港上段青草沙水库的围垦和下段横沙东滩的围垦造成面积和容积减小,其上段和下段容积变化分别为-154.64×106和-511.79×106 m3,对应的变化率分别为-6.75%和-11.55%;南港由于上段河道刷深而下段九段沙以及南汇边滩淤浅、围垦,导致其容积上段增加,下段减小,上段、下段北和下段南容积变化分别为136.39×106、-658.28×106和-1266.11×106 m3,对应的变化率分别为5.62%、-20.73%和-26.06%。  相似文献   
74.
Ombrotrophic bogs are faithful archive of atmospheric metal deposition,but the potential for fens to reconstruct environmental change is often underestimated.In this study,some new data on the Pb depositional history in northeast China were provided using two 210Pb-dated peat sequences from a poor fen in the Fenghuang Mountain of Heilongjiang province.Anthropogenic,detritic and atmospheric soil sources were discriminated using a two-step sequential digestion(weak acid leaching to liberate mobile Pb which is often regarded as anthropogenic Pb,especially for recent samples)and a ratio of unsupported 210 Pb and supported 210 Pb with the logic of that the 214 Pb mainly represents the residual detritus(constant throughout the core)and the unsupported 210 Pb arises from atmospheric fallout.A higher 210Pb/214 Pb suggests more contributions from atmospheric deposition to the Pb content in the peat,and a ratio of 10 was defined to indicate the boundary between detritic input and atmospheric deposition.The detritic Pbwas estimated to be 10~(-1)3 mg·kg~(-1),the anthropogenic Pb ranged from 10-80 mg·kg~(-1),and the atmospheric soil-derived Pb ranged from 5 mg·kg~(-1) to 30mg·kg~(-1).The history of anthropogenic Pb pollution over the last 150 years was reconstructed,and the calculated Pb deposition rate(AR Pb) ranged from 5to 56 mg·m-2·yr~(-1).Using Ti as a reliable reference,the enrichment factor of Pb(EF Pb) relative to the upper continental crust was calculated.Both AR Pb and EF Pb increased with time,especially after the foundation of the People's Republic of China.This is consistent with increasing industrialization and coal burning in the last 60 years in northeast China.The present record of anthropogenic Pb deposition was consistent with the previous reports and an increasing trend of environmental pollution due to anthropogenic activities,in contrasts to Europe and North America which have experienced a major environmental cleanup.For the first time,this work estimates atmospheric Pb deposition via a minerotrophic peat core in China.This will enhance the use of peat archives for studies of environmental change.  相似文献   
75.
76.
A hydro-dynamic model is established on basis of MIKE21 FM to simulate the hydro-dynamic characteristics of Xinghua Bay and investigate the influence of reclamation project on the tidal elevation and tidal currents. Tidal elevation data was obtained at the six tide gauge stations around the Xinghua Bay, and another six current stations were established to observe the tidal current velocity and direction. Validation shows that the model-simulated tidal elevation and tidal currents agree well with observations made at different stations. Predictions are made according to the reclamation project proposed in the regional marine planning of Hanjiang Industrial Park around the port in Putian City. The variations of hydro-dynamic factors, such as tide, current velocity and direction and tidal influx are obtained, and the adverse effect of reclamation on marine environment is discussed. It is shown that the tidal level inside the Xinghua Bay during high tide decreases after the reclamation project is completed. The tidal currents during flooding tide generally decrease in the southeast of the reclamation region, with the maximum decreasing amplitude reaching 0.44 m s-1. On the other hand, the tidal currents during flooding tide increase around the southeast and southwest corners of the reclamation region. The tidal currents during ebb tide increase around the southeast and southwest corners of the reclamation region, with the maximum increasing amplitude attaining 0.18 m s-1. The results in this paper can give some guidance for the marine environment management and the effective utilization of land in Putian.  相似文献   
77.
78.
Radioactive markers are useful in dating lead(Pb) deposition patterns from industrialization in sedimentary archives. As a well-known natural reserve in the world, Yancheng coastal wetland in Jiangsu Province is one of areas most sensitive to global sea level change and is located in the most developed and polluted region of China. Two cores were collected in Yancheng wetland in October 2013 and dated using ~(210)Pb and ~(137)Cs radiometric techniques. Sediments in both cores were sectioned into depth bands and examined systematically for dry bulk density, water content, magnetic susceptibility and grain-size. Multiple elements including Pb were also measured using inductively coupled plasma systems. Unsupported ~(210)Pb activities decreased with depth in both of the two cores, and ~(210)Pb chronologies were established(covering 150 years) using the constant rate of supply(CRS) model. The measured Pb contents ranged from 14.97 mg/kg to 29.40 mg/kg with average values of 17.17–22.79 mg/kg, and the Pb fluxes ranged from 41.70 mg/(m~2·yr) to 172.70 mg/(m~2·yr) with averages of 95.59–123.41 mg/(m~2·yr). Temporal variations of Pb flux, enrichment factors and Pb isotopes show a gradual and continuous increase over time and clearly reflect increased emissions from anthropogenic activities in the region. The Pb isotopic compositions show that most of Pb deposition in Yancheng wetland is input from natural sources by water flows and has the same levels of Pb as in the surface sediment of the Yangtze River and the Pacific mineral aerosol. We also stress the anthropogenic Pb contribution in Yangcheng wetland sediment and the reason of our Pb isotopes not showing anthropogenic signature is likely the instability of anthropogenic Pb in high Fe/Mn oxide conditions. Therefore, more attention should be paid to current local pollution problems, and society should take action to seek a balance between economic development and environmental protection.  相似文献   
79.
Isotope fractionation during the evaporation of silicate melt and condensation of vapor has been widely used to explain various isotope signals observed in lunar soils, cosmic spherules, calcium–aluminum-rich inclusions, and bulk compositions of planetary materials. During evaporation and condensation, the equilibrium isotope fractionation factor (α) between high-temperature silicate melt and vapor is a fundamental parameter that can constrain the melt’s isotopic compositions. However, equilibrium α is difficult to calibrate experimentally. Here we used Mg as an example and calculated equilibrium Mg isotope fractionation in MgSiO3 and Mg2SiO4 melt–vapor systems based on first-principles molecular dynamics and the high-temperature approximation of the Bigeleisen–Mayer equation. We found that, at 2500 K, δ25Mg values in the MgSiO3 and Mg2SiO4 melts were 0.141?±?0.004 and 0.143?±?0.003‰ more positive than in their respective vapors. The corresponding δ26Mg values were 0.270?±?0.008 and 0.274?±?0.006‰ more positive than in vapors, respectively. The general \(\alpha - T\) equations describing the equilibrium Mg α in MgSiO3 and Mg2SiO4 melt–vapor systems were: \(\alpha_{{{\text{Mg}}\left( {\text{l}} \right) - {\text{Mg}}\left( {\text{g}} \right)}} = 1 + \frac{{5.264 \times 10^{5} }}{{T^{2} }}\left( {\frac{1}{m} - \frac{1}{{m^{\prime}}}} \right)\) and \(\alpha_{{{\text{Mg}}\left( {\text{l}} \right) - {\text{Mg}}\left( {\text{g}} \right)}} = 1 + \frac{{5.340 \times 10^{5} }}{{T^{2} }}\left( {\frac{1}{m} - \frac{1}{{m^{\prime}}}} \right)\), respectively, where m is the mass of light isotope 24Mg and m′ is the mass of the heavier isotope, 25Mg or 26Mg. These results offer a necessary parameter for mechanistic understanding of Mg isotope fractionation during evaporation and condensation that commonly occurs during the early stages of planetary formation and evolution.  相似文献   
80.
西秦岭温泉—中川一带实施的1:5万矿产地质调查项目,共圈定1:5万局部高磁异常33处,1:5万地球化学综合异常11处,发现矿点2处,矿化点5处,矿种有金、钼、铁、铜、铷等。通过分析研究区成矿地质条件、1:5万地球物理和地球化学综合异常特征、矿(化)点特征及分布规律等,阐明了该区成矿时空分布规律和矿产共生组合规律,划分成矿远景区9处,提交找矿靶区6处。对其中2处找矿靶区进行槽探验证的结果为: 关子镇幅玉杨观找矿靶区圈定了4条含铷矿化伟晶岩脉和多处铁矿化破碎蚀变带,具有形成伟晶岩型铷矿的潜力; 礼县幅李坝金矿床南侧百叶沟—河西沟找矿靶区圈定了14条蚀变破碎带,在矿化蚀变带内圈定了11条金矿(化)体,具有形成构造蚀变岩(微细粒浸染状)型金矿床的潜力。  相似文献   
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