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1.
The contradiction between the rapid development of aviation market and supply of airspace resources has increased the environmental damages of aviation carbon emission. The conversion and application of environmental damage assessment method of aviation carbon emission were summarized, and the characteristics of the assessment methods for air and ground transportation were compared. We found out the followings:
2.
With the intensification of urbanization and global warming, the problems of urban thermal environment are increasingly prominent. On the basis of the remote sensing, geographic information system, geostatistics and multiscale spatial pattern, the spatial-temporal variation characteristics of land surface temperature in urban thermal environment were quantitatively analyzed. The results are as follows:
3.
Groundwater, as a drinking water source for nearly one third of the world’s urban population, plays a strategic role in the development of urbanization. The object of this study is urban areas with the largest demand for water resources, the heaviest load of groundwater pollution and the most intense development of underground projects. This study sorted out the eco-hydrological problems such as the variation of the groundwater hydrological process, the groundwater pollution, and the urban heat island of groundwater in urban areas under the background of urbanization. Furthermore, the mechanism of changes in the quantity, quality and heat of groundwater was also systematically analyzed, and the intrinsic interaction among these three factors was revealed. The study showed that changes in land use and land cover caused by the urbanization are the main reasons for the variation of groundwater hydrological process. The pollution load of urbanization construction and domestic production waste has aggravated the deterioration of groundwater quality. The increase in vertical heat flux caused by urbanization gives rise to the warming of groundwater. By summarizing the eco-hydrological problems and causes of groundwater in urbanized areas, several suggestions were proposed:
4.
Rice paddies are an important anthropogenic source of methane (CH4) to the atmosphere, which aggravate the global warming greatly. CH4 fluxes from a rice paddy in Central China were continuously measured with the eddy covariance method in 2018. The characteristics, dynamics and drivers of the observed CH4 fluxes from this paddy field were subsequently analyzed. The results indicated that
5.
Boyu Liu Hucai Zhang Fengqin Chang Yang Zhang Xiaonan Zhang Yizhe Feng Huayong Li 《地球科学进展》2020,35(2):198-208
Based on the particle size test results of 36 surface sediment samples from the Cibi Lake, the spatial distribution characteristics and rules of components were discussed by the combination of natural geographical factors with statistical analysis methods in the basin, which provides scientific evidence and basic data for the study of paleoclimate environment in this region. The results show that:
6.
The study on vegetation cover changes based on remote sensing data sources is an important component and frequent topic of earth surface process research. In order to review and summarize the remote sensing data sources and the spatio-temporal pattern of the study areas for vegetation cover changes in China from the perspective of bibliometrics and GIS spatial presentation， the information of remote sensing data sources and study areas were extracted from 1 021 papers on vegetation. Then the composition of remote sensing data sources and their temporal changes in heat which is termed as study frequency， the spatio-temporal scale characteristics of remote sensing data sources and study areas， and the distributions and change characteristics of hot study regions were analyzed. The results show that
7.
Simulating the temporal-spatial distribution of areas suitable for crops is an important part of analyzing the effects of climate change on crop growth, reducing the vulnerability of crop growth, and assessing the adaptability of crop growth to climate change. This study selected climate factors that affect the growth of wheat, maize and rice, and it combined surface soil and ground elevation factors as environment variables, as well as data from agricultural observation stations as species variables. The MaxEnt ecological model was used to identify suitable areas for these three crops during the period of 1953-2012. The areas suitable for the three crops were analyzed to determine the temporal-spatial distribution of major food crops and to estimate the difference in crop growth adaptability under climate change. The results showed the following:
8.
The Qinghai Tibet Plateau (QTP) is an important ecological security barrier region and strategic resource reserve base in China. It is of great significance to explore the construction and impact of its transportation facilities. Through combing the relevant research, we found that:
9.
Characteristics of Carbonate Reservoir and Its Forming Conditions in Continental Lake Basin of China
Jiangmin Du Pengyu Long Peng Yang Qiang Ding Xiuyin Hu Wei Li Yang Bai Jun Sheng 《地球科学进展》2020,35(1):52-69
For decades of exploration, geologists have made great achievements in the exploration of lacustrine carbonate rocks. By dissecting four typical cases of lacustrine carbonate rocks, such as Lucaogou Formation of Permian in Junggar Basin, Da'anzhai Section of Jurassic in Sichuan Basin, Cretaceous in Yin'e Basin and Oligocene in Qaidam Basin, the reservoir characteristics, hydrocarbon generating capacity and reservoir forming model of source rocks were analyzed. The results show that:
10.
The interactions among surface water, groundwater and seawater are closely related in the coastal area with complex hydrological conditions. A series of impacts from human activities and climate change are also more significant in this region. In order to understand the key knowledge and research status of surface water and groundwater interaction in coastal area, it is a useful method to analyze literatures in this research scope in the core database of Web of Science by using CiteSpace. The research achievements in this field were systematically sorted and potential research hotspots were explored, which may provide references for subsequent researches. The results show the following.
11.
Establishing an effective hydrological model is important for guiding the design of small-scale drainage systems. The simulation principle and the sensitivity of key parameters of DRAINMOD model were summarized from four aspects:Hydrological characteristics, nitrogen transport, salt transport and model cooperation. The research application progresses of DRAINMOD model and its coupled model at home and abroad were systematically reviewed, and the limitations and development trends of the model were discussed. It is pointed out that DRAINMOD model has good simulation performance in the fields of agricultural drainage, nitrogen removal and stain reduction. In the simulation of cold area or urban stormwater regulation, domestic research needs to reference from foreign research results. The research suggests that the key research directions of DRAINMOD model could be summarized as the following aspects:
12.
Dengyun Wu Zhikun Ren Lü Honghua Jinrui Liu Guanghao Ha Chi Zhang Menghao Zhu 《地球科学进展》2020,35(4):389-403
Alluvial fans can preserve historical records of sediment transport to middle and lower river systems or piedmont basins, which are considered to be sensitive recorders of climate change and tectonic activity. In this paper, the morphological characteristics, control factors and future development trend of alluvial fan are summarized and described. The main understanding is as follows:
13.
The distribution of frozen soil in our country is very broad, and the area of permafrost alone accounts for 22. 4% of the total land area. As a special kind of soil, frozen soil has many properties that thawing soil does not have due to the influence of ice cement in the soil. Among the many properties of frozen soil, the deformation and strength of frozen soil are the basic problems affecting engineering construction in frozen soil areas. The spherical template indenter test is widely used in the test of the mechanical properties of frozen soil because of its simple test process and relatively accurate test results. Compared with the conventional triaxial test or direct shear test, the test process of the spherical template indenter test is simple and easy to implement, the test period is short, and the sample preparation requirements are low. The advantage of effective cohesion is more significant. Therefore, based on the spherical template indenter test of the frozen soil, this paper estimates the strength and mechanical index of the soil through the indentation depth of the spherical template indenter test, and establishes the relationship between the force of the sample and the indentation depth of the indenter test. The specific test method is as follows:take the water-saturated frozen sandy soil made of different particle size groups(the moisture content of the sample is affected by the particle size in the saturated state)as the research object, study the variation law of the depth of the frozen soil sample pressed into the soil by the spherical indenter with time under the conditions of different fixed loads. By comparing and referring to the frozen sands of each particle size group, the long-term equivalent cohesion of the frozen sands of different particle size groups is summarized. The change law of force(long-term shear strength)with time, and the research method of elastic mechanics to solve space problems, summed up the mutual conversion between the depth St of spherical template indenters pressed into frozen sand samples under different fixed load test conditions relation. The research results show that the long-term shear strength of frozen sand based on the spherical mold test is positively correlated with its particle size. At the same time, since the ice content of frozen soil samples is proportional to its particle size, the long-term shear strength of frozen sand is also proportional to the test. The ice content of the sample increases year-on-year;the long-term shear strength of the frozen sand is related to the maximum contact pressure on the contact surface between the frozen soil and the indenter during the test, which can be expressed as Ct = γq0. The size of the relationship coefficient γ is inversely proportional to the diameter of the spherical indenter. In this paper, the spherical indenter is selected as 22 mm, and γ=3. 82×10-3. By establishing the relationship between the maximum contact pressure q0 and the long-term shear strength Ct When the maximum contact pressure q0 is the same under different fixed loads, the long-term shear strength Ct is also the same. According to this, the depth curve and the freezing depth of the frozen sand pressed into the soil by the spherical indenter over time under different fixed loads can be converted. Long-term shear strength curve of frozen sandy soil with time. It has been verified by experiments that the conversion curve of the depth of the indenter pressed into the soil with time under a fixed load of 7. 0 kg is highly consistent with the measured curve of the depth of the indenter pressed into the soil with time under a fixed load of 5. 1 kg and 7. 0 kg. © 2022 Nanjing Forestry University. All rights reserved. 相似文献
14.
The Glycerol Dialkyl Glycerol Tetraethers (GDGTs) occur ubiquitously in a wide range of environments, such as loess, peat, lake, soil, and ocean, which vary compositionally in response to environmental changes, and provide a series of biomarker proxies for paleoenvironmental reconstruction. This paper introduced the structures and biological sources of GDGTs, and reviewed the recent progresses of the application of the GDGTs proxies in the paleoenvironmental reconstruction of loess deposits. The main progresses include:
15.
As the turning point of the Yellow River flowing from the Tibetan Plateau to the Loess Plateau, the valley evolution of Lanzhou Basin is of great significance to the study of the evolution of the Yellow River system in different geomorphic units. The evolution of the Yellow River Valley in Lanzhou has been studied for nearly 100 years. In the process of research, important research results and understandings have been obtained as follows:
16.
Cherts contain important information of paleogeography, paleostructure and paleo-ocean, which is the important means of studying petrotectonics. With regard to the major disputes on the sedimentary environments, origin and source of Gufeng Formation bedded cherts in the northern margin of middle-lower Yangtze area, demonstrations from both forward and reverse aspects from the perspective of the sedimentary-tectonic evolution were given. By summarizing previous views on the genesis of bedded cherts in Gufeng Formation, and extensively collecting published original geochemical data, in the forward demonstrations we created the database of the cherts about rare earth elements to systematically identify the sedimentary environments, origin and source of cherts. By sorting out the time and cause of the main geological events in the middle Permian in south China, in the reverse demonstrations we established the sequence of tectonic evolution to verify or explain the current series of disputes. The results show that:
17.
The notion of Resilience of Social-Ecological Systems (ReSES) in balancing and sustaining development are increasingly breeding more multidisciplinary attentions from world scientists and government managers. However, with the tremendous growing in theoretical system, certain problems hinder the integration of theory and practice, such as the low degree of research recognition, lacking of unified paradigm, unevenly development of research topics, etc. Thus, it is an urgent need to sort out the construction, source and development in theory, and its gaps with practices. To identify the hotspot in current research, including the fundamental theories and methods, current focus and future trends, a bibliometric analysis integrating Citespace and TDA tools were made. Using searching queries on “system resilience”, 10 315 articles in Web of Science database were retrieved. Then, a series of contents were examined on these publications, including:
18.
Daily routine observation data from 274 meteorological stations in the Qinghai-Tibetan Plateau and its surrounding areas from 1970 to 2017 were utilized to examine the spatial patterns and abrupt changes of potential evapotranspiration with the formula of FAO Penman-Monteith, in consideration of China’s eco-geographical divisions. The results showed that
19.
地下水硝酸盐污染已成为世界范围内最严重的环境地质问题之一。全面并准确识别硝酸盐污染源,对地下水的有效管理及污染防治具有重要的指导意义。从地下水硝酸盐来源、同位素检测方法、污染源同位素特征、定量解析模型构建、硝酸盐主要转化过程及同位素分馏效应等方面进行总结,比较不同解析方法在硝酸盐溯源中的应用与发展,建议采用多学科、多方法相结合的方式,提高对硝酸盐污染源的全面理解。同位素富集系数是定量解析硝酸盐污染源的重要参数,在源解析过程中探讨硝酸盐转化及同位素分馏机制,能够更好地诠释地下水硝酸盐来源和迁移转化过程,提高源解析的准确性,为地下水硝酸盐污染的准确溯源与有效防治提供参考。 相似文献
20.
高氯酸盐( )是一种小分子量、有毒的无机络阴离子,普遍存在于环境中。由于其分子大小与碘离子相似,会干扰人体甲状腺的正常功能,因此其环境污染问题引起了广泛的关注。本文选取污染场地的天然河沙为试验材料,主要通过柱实验对地下水中 自然衰减过程进行研究,考察了铁氧化物、 对 自然衰减过程产生的影响。结果表明,高氯酸盐自然衰减过程主要由微生物驱动,天然河沙可去除2 mg/L的 ,但其过程缓慢且还原量有限,长期去除率不超过10%,其限制因素为缺乏电子供体;铁氧化物可以促进 自然衰减,但当溶解性铁的浓度低于5.5 mg/L时,衰减过程开始受到影响;地下水中的 会抑制 的降解,当 低至10 mg/L或以下时, 才开始明显降解。 相似文献