Sedimentary Dynamics of the Sands of the Cover Formation in the Batéké Plateaus (Republic of Congo): Paleoenvironmental Implications

The depositional environment of the sands of the cover formation is discussed. This study aims to determine the paleoenvironments of deposition of the sands of the cover formation in the Batéké Plateaus by studying sedimentary dynamics based on the description of lithological facies in the field and granulometric analyses in the laboratory. In the field, six (6) lithostratigraphic logs were surveyed and 42 sand samples were taken for laboratory analysis. In the laboratory, the samples underwent granulometric, sieving and sedimentometry analyses, after washing with running water using a 63 µm sieve. These analyses made it possible to determine the granulometric classes of the samples. The sieving results allowed to determine the granulometric parameters (mean, standard deviation, mode, median, skewness, flattening or kurtosis) using the method of moments with the software “Gradistat V.8”, granulometric parameters with which the granulometric facies, the mode of transport and the deposition environment were determined using the diagrams. Morphoscopy made it possible to determine the form and aspect of the surface of the quartz grains constituting these sands. Granulometric analyses show that these silty-clay or clayey-silty sands are fine sands and rarely medium sands, moderately to well sorted and rarely well sorted. The dominant granulometric facies is hyperbolic (sigmoid), with parabolic facies being rare. The primary mode of transport of these sands is saltation, which dominates rolling. The dispersion of points in the diagrams shows that these sands originate from two depositional environments: aeolian and fluvial. Morphoscopic analysis reveals the presence of clean rounded matt grains (RM), dirty rounded matt grains (RS), shiny blunt grains (EL) and shiny rounded grains (RL). The rounded matt grains exhibit several impact marks. The presence of dirty rounded grains with a ferruginous cement on their surface indicates that these sands have been reworked. These sands have undergone two types of transport, first by wind (aeolian environment) and then by water (fluvial environment).

Spatiotemporal variation of ecological environment quality and extreme climate drivers on the Qinghai-Tibetan Plateau

Protecting the ecological security of the Qinghai-Tibet Plateau(QTP)is of great importance for global ecology and climate.Over the past few decades,climate extremes have posed a significant challenge to the ecological environment of the QTP.However,there are few studies that explored the effects of climate extremes on ecological environment quality of the QTP,and few researchers have made quantitative analysis.Hereby,this paper proposed the Ecological Environmental Quality Index(EEQI)for analyzing the spatial and temporal variation of ecological environment quality on the QTP from 2000 to 2020,and explored the effects of climate extremes on EEQI based on Geographically and Temporally Weighted Regression(GTWR)model.The results showed that the ecological environment quality in QTP was poor in the west,but good in the east.Between 2000 and 2020,the area of EEQI variation was large(34.61%of the total area),but the intensity of EEQI variation was relatively low and occurred mainly by a slightly increasing level(EEQI change range of 0.05-0.1).The overall ecological environment quality of the QTP exhibited spatial and temporal fluctuations,which may be attributed to climate extremes.Significant spatial heterogeneity was observed in the effects of the climate extremes on ecological environment quality.Specifically,the effects of daily temperature range(DTR),number of frost days(FD0),maximum 5-day precipitation(RX5day),and moderate precipitation days(R10)on ecological environment quality were positive in most regions.Furthermore,there were significant temporal differences in the effects of consecutive dry days(CDD),consecutive wet days(CWD),R10,and FD0 on ecological environment quality.These differences may be attributed to variances in ecological environment quality,climate extremes,and vegetation types across different regions.In conclusion,the impact of climate extremes on ecological environment quality exhibits complex patterns.These findings will assist managers in identifying changes in the ecological environment quality of the QTP and addressing the effects of climate extremes.

Countermeasures for Qinghai-Tibet Plateau to Cope with Climate Change and Ecological Environment Safety

The monitoring,prediction and assessment of status about climate changes and ecological environment at home and abroad were discussed in this study,and the scientific significance and countermeasures for Qinghai-Tibet Plateau to cope with these problems were also put forward.

PROGRESS IN STUDIES ON GEOGRAPHICAL ENVIRONMENTS OF THE QINGHAI-XIZANG PLATEAU

The Qinghai Xizang (Tibet) Plateau area was subjected to twice uplift and planation in the Tertiary. Intense uplifting of the plateau area has given rise to drastic changes and differentiation of physical environment on the plateau and the surrounding area since 3.4 Ma B.P. Significant environmental changes with dry tendency in interior of the plateau had occurred during the last 150 ka B.P. By comparative study on several mountains of the plateau, two systems of the structure type of the altitudinal belt are identified and nine groups are subdivided . A distribution model with close relevance to highland uplift effect has been generalized. A number of striking geo ecological phenomena and their spatial pattern such as moisture corridor, dry valleys, high cold meadow zone, and high cold arid core area are investigated and discussed. Based on the thermal conditions, moisture regimes and variation in landforms of the plateau is sequentially demarcated. A tentative scheme of 2 temperature belts, 10 natural zones and 28 physical districts has been proposed not including southern slopes of the East Himalayas. The Qinghai Xizang Plateau is sensitive to “green house effect”, showing close relation with global change. Characteristics of temperature and precipitation on the plateau during the last 2000 years, and response of glaciers, snow deposit and permafrost on the plateau to global change are dealt with in the present paper.

The response between glacier evolution and eco-geological environment on the Qinghai-Tibet Plateau

Based on the remote sensing survey and monitoring results of snow lines on the Qinghai-Tibet Plateau, the authors analyzed the following eco-geological factors such as water resources, permafrost, desertification, wetlands, lake, geological disasters, sea-level rising, earthquake, etc., affected by the change of snow lines over the past 40 years, and discuss the response between glacier evolution and the eco-geological environment preliminarily.

The Impact of Climatic and Environmental Factors on n-Alkanes Indices in Southwestern Tibetan Plateau

n-Alkanes are widely used in paleoenvironmental reconstructions.However,our understanding of changes in the distribution of n-alkanes with climatic and environmental factors remains unclear in arid/semi-arid regions.We sampled 26 surface sediments from three climatic zones across the southwestern Tibetan Plateau to evaluate the sensitivity of chain length distributions of n-alkanes to climatic and environmental parameters.Our observations demonstrate that average chain length(ACL),proportion of aquatic macrophyte(Paq),carbon preference index(CPI)and ratio of the contents of nC_(27)and nC_(31)(nC_(27)/nC_(31))are all sensitive to hydroclimatic conditions.In contrast to commonly-adopted assumptions,the correlations between these indices and hydrological parameters are not always good,which indicates that the interpretation of n-alkane indices is special on the southwestern Tibetan Plateau.These might be related to the vegetation characteristics and seasonality of biological activity,and need to be considered in paleoclimatic reconstruction.The impact of seasonal precipitation on n-alkanes indices was also evaluated.

Soot particle distributions inside a diesel particulate filter during soot loading in plateau environment

A three-dimensional diesel particulate filter(DPF)simulation model was developed by using AVL software FIRE to study the effects of four factors on soot particle distributions along the axial and radial directions in the DPF after the model accuracy was validated.An orthogonal test method was used to determine the importance and weights of the design of experiments(DoE)factors such as the expanding angle,the number of channels per square inch,and the exhaust mass flow rate.The effects of these factors on the uniformity of the soot particle distributions were also analyzed.The results show that when the soot loading time was 400 s,the soot particles inside the DPF along the axial direction exhibited a bowl shape,which was high on the both ends and low in the middle.The uniformity of the axial distribution of soot particles reduces significantly with an increase in the number of channels per square inch.The uniformity of the radial distribution reduced with an increase in the expanding angle of the divergent tube.Based on the impacts on the axial uniformity,the three most influencing factors in a descending order are the number of channels per square inch,the exhaust mass flow rate,and the expanding angle of the divergent tube.

Research on Rapid Initial Adaption to the Environment of a Plateau

We designed two types of pre-adaption plans for this study. One was a pre-adaption training with progressive intermittent hypoxia, with a constant lower pressure oxygen tank used in the plain before arriving at the plateau （PG）. The other was by progressively increasing the time of exposure to hypoxia with oxygen supplied in stages after radical plateau （RG）. By testing the blood oxygen saturation （SpO2）, heart rate （HR）, and quality of sleep after arriving at the 3800 m high plateau, results showed that the pre-acclimatization and radical groups performed better than the control group （CG）. Both strategies were equivalent in terms of effects and principles in providing more flexible choices for acclimatization.

Determining the groundwater basin and surface watershed boundary of Dalinuoer Lake in the middle of Inner Mongolian Plateau,China and its impacts on the ecological environment

The surface watershed and groundwater basin have fixed recharge scale,which are not only the basic unit for hydrologic cycle research but also control the water resources formation and evolution and its corresponding eco-geological environment pattern.To accurately identify the boundary of the surface watershed and groundwater basin is the basis for properly understanding hydrologic cycle and conducting the water balance analysis at watershed scale in complicated geologic structure area,especially when the boundary are inconsistent.In this study,the Dalinuoer Lake located in the middle of the Inner Mongolian Plateau which has complicated geologic structure was selected as the representative case.Based on the multidisciplinary comprehensive analysis of topography,tectonics,hydrogeology,groundwater dynamics and stable isotopes,the results suggest the following:(1)The surface watershed ridge and groundwater basin divide of Dalinuoer Lake are inconsistent.The surface watershed was divided into two separate groundwater systems almost having no groundwater exchange by the SW-NE Haoluku Anticlinorium Fault which has obvious water-blocking effect.The surface drainage area of Dalinuoer Lake is 6139 km^(2).The northern regional A is the Dalinuoer Lake groundwater system with an area of 4838 km^(2),and the southern regional B is the Xilamulun Riverhead groundwater system with an area of 1301 km^(2).(2)The groundwater in the southern of regional A and the spring-feeding river are the important recharge sources for the Dalinuoer Lake,and it has greater recharge effects than the northern Gonggeer River system.(3)It is speculated that the trend of Haoluku Anticlinorium Fault is the boundary of the westerlies and the East Asian summer Monsoon(EASM)climate systems,which further pinpoints the predecessor’s understanding of this boundary line.At present,the Dalinuoer Lake watershed is proved to have gone through a prominent warming-drying trend periods,which leads to the precipitation reduction,temperature rise,human activities water usage increasement.So the hydrological cycle and lake eco-environment at watershed scale will still bound to be change,which may pose the potential deterioration risk on the suitability of fish habitat.The results can provide basic support for better understanding water balance evolution and lake area shrinkage cause as well as the ecological protection and restoration implementation of Dalinuoer Lake watershed.

Response of Lake Environment to Climatic Changes on The Tibetan Plateau,Western China

The large-scale summer monsoon circulations of south Asia makes a strong impact on precipitation in the area of southwestern China including Qinghai-Tibetan Plateau and Yun-Gui Plateau.however,the monsoon is both spatially and temporally complex and smaller-scale circulations are forced by a variety of local or regional orographic effects,local or regional land-atmosphere or

Geochemical Evolution and Environmental Changes of Qinghai-Xizang Plateau Since Late Cenozoic

Long and short-term climatic curves were preliminarily established based on thecomprehensive analysis of gaxhemical information since the Late Cenozoic in the Qinghai-Xizang (Qinghai-Tibet) Plateau. The curves show that the climate in the plateau was alterna-tively dry-wartn and cod-wet during the peried of 30 - 3. 4 Ma when the plateau was not up-lifted to an enough altitude and the monam was not completely formed either. In the peried of3. 4 - 0. 73 Ma, the climate fluctuated between dryco1d and wet-warm when the plateau wasrapidly uplifted and the Asian monam was conequently formed. Since 0. 73 Ma, the climatebecame even drier when the plateau continuously are. In the Holocene period, the climate alternatively changed with a complex medel of being coo-dry, warm-wet and cold-wet.

Spatio-temporal variability of periphytic protozoa related to environment in the Niyang River,Tibet,China

The Niyang River, a main tributary of the Yarlung Zangbo River, is an important and typical plateau fiver ecosystem in Tibet, China. At present, few studies have focused on its aquatic living resources and fiver ecology. In this study, the composition, abundance, and diversity of periphytic protozoa were investigated across four seasons from 2008 to 2009 to better understand their spatio-temporal patterns and relationship to the environment. Our investigation shows that periphytic protozoa in the Niyang River contained 15 genera, belonged to Tubulinea, Alveolata, Discosea and Rhizaria, Alveolata possessed most genera, up to nine, with highest share in abundance, exceeding 50%, Difflugia and Glaucoma were dominant genera. Moreover, four diversity indices of periphytic protozoa, including species richness, total abundance, Shannon-Wiener diversity index and Pielou＇s evenness index, displayed a significant descending trend as the seasons continued, in the order of winter, spring, summer and autumn; with a significant difference existing between winter and summer （or autumn） for Shannon-Wiener diversity index and species richness （P〈0.05）. Four of these diversity indices also presented a V-shaped pattern between the upper middle course of the Niyang River and the confluence of the Niyang River and Yarlung Zangbo River, with the lowest value occurred in the middle course of the Niyang River. However, no significant variation was found through the Niyang River （P〉0.05）. In addition, canonical correlation analysis （CCA） shows that the densities of Difflugia, Glaucomais, Enchelydium, Cyphoderia, and Enchelys correlate with water temperature, alkalinity, hardness, pH, and dissolved oxygen, respectively. Lastly, the relationship between periphytic protozoa diversity and the environmental factors of the Niyang River can be predicted using classification and regression trees （CART） annalysis, which suggests that the total abundance and Shannon-Wiener diversity index would be higher when the elevation is above 3 308 m. On the other hand, the Shannon-Wiener diversity index and Pielou＇s evenness index would be lower when pH and ammoniacal nitrogen have lower or higher values. Finally yet importantly, close attention should be paid to periphytic protozoa and its environment to ensure sustainable development of the Niyang River ecosystem.

Characteristics of Water Environment in Regions of Zhaling and Eling Lakes near Waterhead of Yellow River

Conditions of the water environment in the region of the Zhaling and Eling lakes, which are located in the frozen earth zone on the Qingzang plateau, are unique. The equilibrium of the water quantity of the two lakes is maladjustment under the condition of a dry and cold climate in which evaporation is greater than precipitation. The Zhaling and Eling lakes have been atrophying, leaving three lake terraces and star studded lagoons around the two lakes since Holocene. When these lagoons were separated from the original lakes, they became cut lake basins, and were transformed from fresh water lakes into salt water lakes, salt lakes or salt playas owing to strong evaporation. This kind of evolutionary process will continue in the future.

Extracting water body data based on SDWI and threshold segmentation:A case study in permafrost area surrounding Salt Lake in Hoh Xil,Qinghai-Tibet Plateau,China

There are a large number of lakes,rivers,and other natural water bodies distributed in the permafrost area of the Qinghai-Tibet Plateau(QTP).The changes in water bodies will affect the distribution of water resources in sur-rounding areas and downstream areas,resulting in environmental impact and bringing potential flood disasters,which will induce more serious issues and problems in alpine and high-altitude areas with a fragile habitat(such as the QTP in China).Generally,effective,reasonable,and scientific monitoring of large-scale water bodies can not only document the changes in water bodies intuitively,but also provide important theoretical reference for subsequent environmental impact prediction,and disaster prevention and mitigation in due course of time.The large-scale water extraction technology derived from the optical remote sensing(RS)image is seriously affected by clouds,bringing about large differences among the extracted water result products.Synthetic aperture radar(SAR)RS technology has the unique advantage characteristics of all-weather,all-day,strong penetration,and not being affected by clouds,which is hopeful in extracting water body data,especially for days with cloudy weather.The data extraction of large-scale water bodies based on SAR images can effectively avoid the errors caused by clouds that become prevalent at present.In this paper,the Hoh Xil Salt Lake on the QTP and its surrounding five lakes are taken as the research objects.The 2-scene Sentinel-1 SAR image data covering the whole area on 22 August 2022 was used to verify the feasibility of extracting water body data in permafrost zones.Furthermore,on 22 August 2022,the wealth here was cloudy,which made the optical RS images,e.g.,Sentinel-2 images full of clouds.The results show that:using the Sentinel-1 image and threshold segmentation method to extract water body data is efficient and effective with excellent results in permafrost areas.Concretely,the Sentinel-1 dual-polarized water index(SDWI),calculated by combining dual vertical–vertical(VV)polarized and verti-cal–horizontal(VH)polarized data is a useful index for water extraction and the result is better than each of the VV or VH polarized images.

高原环境下重型车辆排放物生成机制分析

针对高原环境下重型车辆排放物生成机制尚不清晰的问题,以1辆搭载国六重型柴油发动机的车辆作为研究对象,在海拔2 400 m左右高原环境下,利用便携式排放测量系统(PEMS)设备,对不同负荷工况车辆冷启动过程排放污染物的瞬态变化趋势进行了研究。结果表明,受高原稀薄空气的影响,运行前期,车辆在高负荷工况下CO排放更高,且与10%和50%负荷不同,100%负荷下,NOx、NO和NO2排放峰值主要出现在运行时间300~500 s;在高负荷工况下,车辆碳烟颗粒排放量高,但水温增加后,碳烟颗粒排放迅速下降。冷起动过程中CO、NOx和碳烟颗粒数量浓度(PN)仍是排放污染物控制的关键项目,特别是在高原环境下。

高原环境导致的中青年驾驶行为及驾驶绩效特征

为了量化分析高原环境导致的驾驶行为特征差异,寻找驾驶绩效下降时间窗,运用驾驶模拟器和低氧发生器在平原地区模拟海拔3 900 m高原驾驶环境,开展驾驶模拟试验分别收集驾驶人在平原环境和模拟高原环境的驾驶行为数据和心电图(electrocardiogram,ECG)信号数据。通过对比高原实车试验环境驾驶人的心率指标变化,运用雷达图、数值排序图和单因素方差分析方法对平原、高原环境下的驾驶行为特征进行对比分析,引入Jensen-Shannon散度(JS散度)量化2种环境下横向偏移距离、横向加速度、转向盘旋转率和速度这4个指标的概率密度拟合分布之间的差异,使用差分法确定高原环境下的驾驶绩效下降时间,验证了模拟高海拔环境驾驶模拟试验的有效性研究。结果表明:高原环境下横向偏移距离标准差、横向加速度标准差、转向盘旋转率标准差、速度标准差比平原环境下分别增加了0.094 3 m,0.119 0 m/s^(2),0.000 9°/s,0.651 3 km/h,车辆整体稳定性降低;借助JS散度发现横向偏移距离、横向加速度、转向盘旋转率和速度这4个指标在2种环境下的数值分布存在较大距离,分别为0.23,0.11,0.01,0.02,其中车辆的横向运动受负面影响更大;在进入海拔3 900 m的高原地区时,驾驶绩效约在6 min后显著下降。

增压方式对高原重型天然气发动机性能研究

国六当量重型天然气发动机普遍采用单级废气涡轮对新鲜充量进行增压,在高原低压环境下,相对较低的进气密度,单级废气涡轮增压方式无法提供工况稳定高效运行所需要的增压需求,导致发动机动力下降问题突出。为研究不同增压方式对国六当量重型天然气发动机高原性能的影响,通过发动机模拟高原台架测试,分析了单级废气涡轮增压和两级增压两种不同增压方式发动机在模拟高原低压环境下的性能表现。试验结果表明:两级增压方式可明显改善重型天然气发动机在高原低压环境下的动力下降问题。相比单级废气涡轮增压方式,在发动机安全运行的边界条件内,两级增压方式在平原环境下的功率密度可提升13.7%;2km海拔下发动机实现无功率损失,功率下降改善13%;2.5km海拔下发动机动力无损失;3km海拔下动力下降问题改善幅度较大,最大降幅由27.5%降低为10.2%。此外,高原低压环境下发动机增压器转速安全裕度的增加大大降低了增压器超速断轴问题的风险,提升了发动机运行的耐久可靠性。

青藏高原隆升对中国疆域自然环境的影响:破解“胡焕庸线”的思考

中国疆域广大,人口、土地、耕地和发展程度很不均衡。1935年,知名学者胡焕庸据此提出了著名的“胡焕庸线”。利用这条北东-南西走向直线,将中国大陆划分为东西两个部分。该线的东、西两侧差异悬殊。究其缘由,制约因素多元,而近地表的自然环境和地球内部物质与能量的交换起着重要作用。研究与探索表明:印度次大陆与欧亚大陆两陆-陆板块的碰撞-挤压驱使高原南缘喜马拉雅造山带的突起是根本原因。喜马拉雅造山带的突起阻隔了印度洋南来温湿气流的北进,并形成了西风带,造成了中国西北地域的干旱和荒漠化。在力系作用下,壳、幔物质重新分异、调整,地壳短缩增厚、高原整体抬升不仅导致东、西两部降水量、气温、人口、耕地与生态环境的显著改变,且地球物理场发生了强烈变异与分布不均。西部发展的关键在于水,水进则人进,人进则文化进,文化进则科技进,科技进则发展快,西部人民生活与生存环境不断优化,社会则更安宁。东部不断强化开辟与利用地下空间,西部期盼“红旗河”西部调水工程实施,维护生态环境,兴建亿亩现代化耕地、牧场与绿洲。中国东部与西部共同发展与建设十分重要,饭碗要永远端在自己手中。

模拟高高原机场疏散的低氧实验平台设计

为克服高高原机场疏散研究中实地实验的挑战,设计并研制了一套可以模拟高高原环境的低氧实验平台。综合利用文献调研、实验室测试等方法,分别从生理层面与认知层面设计了三组对照实验方案,即上下台阶实验、90 s跑步实验和反应能力实验,以模拟真实疏散情景。基于统计学原理,对比分析了高高原实地实验与低氧实验平台实验得到的心率、血氧、反应能力等数据。研究结果表明,三组对照试验数据无显著差异性,验证了该平台模拟高高原环境的可行性和合理性。该实验平台可为安全人机、职业卫生等领域的实验研究与教学创新提供支持。