Transformation pathway of carbonate pedofeatures based on their micromorhology and carbon isotope data in the Northern Caucasus region, Russia

Carbonate pedofeatures （CPs） in a chronosequence of paleosols buried under kurgans in the Northern Caucasus region of Russia in a period from the end of the 4th to the middle of the 5th centuries AD （It seams that there is no time left） were studied by using a set of morphological and isotopic methods. The CPs in chernozem-type soils of Russia are usually represented by crystallomorphic calcite whereas the non-segregated carbonates occurred at the same horizons - by collomorphic one. Those two morphotypes of calcite have the differences in elemental composition and isotopic composition of carbon and, hence, should have different origins - from true and colloidal solutions, respectively. The same differences including radiocarbon age have been revealed for pseudomycelium of the ABca horizon of the youngest paleosols as compared with the same CPs of other paleosols in the chronosequence studied. Our assumption is that it was succeeded in finding that the pseudomycelium right away after its precipitation from a colloidal solution migrated from the lower soil horizons to the surface horizons during the periods of climatic aridization. After a short time interval （not more than 25-50 years） collomorphic calcite in the pseudomicelium of the yongest paleosols mentioned above will likely become by ＂usual＂ acicular calcite.     

Evaluation of soil erosion from chestnut forests: A case study in the Yanshan Mountains,China

Soil erosion from chestnut forests has many types and intensities. However, less attention has been paid to the increasing soil erosion in the chestnut forests of Yanshan Mountains region, North China. The objective of this study was to discuss forest ages(5, 5~10, 10~20, and 20~ yr), slopes(5°~15°, 15°~25°, 25°~35°, and 35°~), slope positions(upslope, midslope, downslope, and whole slope), and slope aspects(sunny, half-sunny, shade, and half-shade) effects on soil erosion types and intensities in chestnut forests. A field survey was applied to investigate in detail the contiguous chestnut forests near Changfu village of Hebei Province, China on October 9-30, 2016. Results showed that chestnut forests are dominated by moderate erosion in this region, and the soil erosionfrom chestnut forests tended to deteriorate gradually. The average land degradation index was 0.31. The erosion intensity from chestnut forests will gradually increase with the year of planting. Most of the slopes are greater than 15°, accounting for 86.7% of the total chestnut forests. Most of the chestnut forests occupy the whole slope, accounting for 47.5% of the total area. Moderate erosion occurs most commonly for different slope aspects. In conclusion, improving the preparation efficiency of chestnut forests and enhancing the construction standards of soil and water conservation measures would be useful measures to avoid soil erosion from chestnut forests reaching a more severe level.     

Effects of wetland vegetation on soil microbial composition: A case study in Tumen River Basin,Northeast China

Hydrology plays a dominant role in wetland plant distribution and microbial composition, but few studies explicitly attempted to relate the linkage between wetland vegetation and microbial community. The present study consisted of five wetland plant communities along three adjacent flood gradients zones (zone 1 dominated by Carex appendiculat, zone 2 dominated by Eleocharis ovate, and zone 3 dominated by Phragmites australis/Bidens pilosa/Calamagrostis angustifolia, which formed separate, monoculture patches). Gram negative and arbuscular mycorrhizal fungal phospholipid fatty acid (PLFA) are more abundant in the site with short flooding period (zone 3) than in the site with long flooding period (zone 1), and they are also different in the P. australis, B. spilosa and C. angustifolia of zone 3. Principle Component Analysis (PCA) showed that the flooding period could explain 92.4% of variance in microbial composition. Redundancy Analysis (RDA) showed that available nitrogen (AN), total nitrogen (TN) and soil organic matter (SOM) could explain the 79.5% of variance in microbial composition among E. ovata, P. australis, B. pilosa and C. angustifolia. Results demonstrated that flooding period was the main factor in driving the microbial composition and plant-derived resources could influence soil microbial composition in the seasonally flooded zones.     

Effects of geomorphology and soil conditions on vegetation structure in conserved desert wadis: A case study of Jal AlZor escarpment,Kuwait

Variations in phytogeography of Jal Al-Zor wadi system in Sabah Al Ahmad Nature Reserve, an arid national park in Kuwait, in relation to physiographic and edaphic conditions were investigated using alpha diversity and multivariate analyses. A total of 66 plant species were recorded at low-relief and high-relief wadis. Altitude and slope gradients, grain size distribution and soil texture properties had a significant relationship with plant cover and plant diversity. There was a high diversity of life-forms along the wadi system with a dominant of therophytes(annuals) particularly in spring after winter rainfalls. Chamaephytes and hemicryptophytes were the dominant perennial life-forms. A chorological analysis documents the strong effect of Saharo-Arabian chorotype on the vegetation of the study area. Cluster analysis clarified eight vegetation assemblages along altitude and slope gradients within the wadi system. Alpha diversity of plant species was greater in plant assemblages at low-relief wadis than at high-relief wadis. Vegetation structure in this study showed that phytogeographically, wadis of Jal Al-Zor were closely related to the wadis in the Arabian deserts. The slope gradient pattern and edaphic conditions of plant assemblages and plant diversity in the conserved wadis of Jal Al-Zor may be suggested as a reference model for restoration strategy of disturbed low elevated wadis in the surrounding desert regions.Restoration would include propagation of suitable plants such as Stipagrostis plumosa-Haloxylon salicornicum-Rhanterium epapposum.     

Spatial variability of soil development indices and their compatibility with soil taxonomic classes in a hilly landscape: a case study at Bandar village,Northern Iran

Soil complexity and its multivariable nature restrict the precision of soil maps that are essential tools for soil sustainable management. Most methods developed for reducing impurities of soil map units focus on soil external properties. Taking into account the soil internal properties like geochemical weathering indices could increase the map unit’s purity. However, the compatibility of these indices with Soil Taxonomic Classes has not been studied yet. This study has been performed in a hilly region with different soil types, vegetation and diverse topographic attributes to illustrate the spatial variability of soil weathering indices and their compatibility with Soil Taxonomic Classes. The grid sampling is at 100 m interval. Physico-chemical and total elemental analyses were performed on 184 and 56 soil samples respectively. Eight topographic attributes and 14 common soil development indices were determined. Principal components analysis (PCA) was done to identify the most important components. The results indicated that Morphological Index (MI) was the best index to show the degree of soil development in the studied region. Spatial distribution of Soil Taxonomic Classes showed relatively good compatibility with the first principal component (PC1), Vogt (V) and morphological indices. This study showed that using soil development indices with the conventional methods could be helpful tools in soil survey investigations     

Estimation of sediment load and erosion of different geological units: A case study from a basin of north-eastern Iran

Erosion of geological units and sediment load in rivers can be considered as the serious problems in recent decades.Increasing sediment loads generate major hazards for water resources development,particularly in terms of loss of reservoir storage due to sedimentation and siltation of water distribution systems.In this paper,the performance of four sediment rating curve (SRC) development methods was evaluated for the Shirin Darreh River(SDR) basin (1750 km2),located in North Khorasan Province,Iran.Data of flow discharge (Q) and suspended sediment flux (SSF)(Q-SSF pairs,N=957)and daily flow discharge,recorded by the Regional Water Company of North Khorasan (RWCNK) at the Qaleh-Barbar (QB) gauging site during 1989-2018were used.The flow discharge classification method performed best by meeting the desired criteria of most statistical indices,including normalized root mean square error (NRMSE),mean bias error (MBE),mean absolute error (MAE),index of agreement (d),and coefficient of determination (R~2).Based on the optimized method,the rate of suspended sediment transportation at the study site was estimated about2.7×10~6 ton year~(-1).Erodibility of the exposed formations in the study area was estimated based on a factorial scoring model (FSM).Three indices,focused on the outcrop and erodibility,were calculated for the geological units at sub-basin and total scales.Marl deposits are the most extensive geological unit in the three sub-basins and the maximum formation outcrop ratio (FOR) and participation in erosion (PCE)were obtained for these rocks at total scale.In fact,marl unit can be regarded as the main source to supply the suspended sediments in the study basin.     

Bofedal response to climate variability,local management,and water extraction:A case study of Chucuyo,Northern Chile

Andean high-altitude wetlands are important ecosystems that serve a range of social-ecological functions.In the Andes,bofedales,a specific type of peat-producin...     

Differences of polygonal faults related to upper Miocene channels: a case study from the Beijiao sag of Qiongdongnan basin,South China Sea

Deep-water coarse-grained channels are embedded within a polygonal fault tier, and the polygonal faults (PFs) present non-polygonal geometries rather than classic polygonal geometry in plan view. However, PFs present differences when they encounter deep-water (coarse-grained vs. fine-grained) channels with different lithology, which has not been further studied to date. 3D seismic data and a drilling well from Beijiao sag of Qiongdongnan basin, South China Sea were utilized to document the plan view and cross-sectional properties of the PFs and their differences and genetic mechanism were investigated. Results show that, first, PFs can be divided morphologically into channel-segmenting PFs and channel-bounding PFs in plan view. The former virtually cuts or segments the axes of channels in high- and low-amplitudes, and the latter nearly parallels the boundaries of the channels. Both are approximately perpendicular to each other. Secondly, channel-bounding PFs that related to low-amplitude channels are much longer than those of high-amplitude ones; channel-segmenting PFs related to low-amplitude channels are slightly longer than the counterparts related to high-amplitude channels. Lastly, the magnitudes (e.g., heights) of the PFs are proportional to the scales (e.g., widths and heights) of low-amplitude channels, whereas the magnitudes of the PFs are inversely proportional to the scales of high amplitude channels. Coarse-grained (high amplitude) channels act as a mechanical barrier to the propagation of PFs, whereas fine-grained (low-amplitude) channels are beneficial to the propagation and nucleation of PFs. Additionally, the genetic mechanism of PFs is discussed and reckoned as combined geneses of gravitational spreading and overpressure hydrofracture. The differences of the PFs can be used to reasonably differentiate coarse-grained channels from fine-grained channels. This study provides new insights into understanding the different geometries of the PFs related to coarse-grained and fine-grained channels and their genetic mechanism.

     

鄂尔多斯盆地陆相页岩孔隙演化特征——以长7油层组为例

以鄂尔多斯盆地三叠系延长组7段长7油层组陆相页岩为对象,基于X线衍射、场发射扫描电镜、等温吸附、物性测试及岩石热解等实验,研究陆相页岩孔隙演化特征。结果表明:研究区页岩孔隙直径和黏土矿物演化程度呈正相关关系,演化程度越高,黏土矿物平均孔径越大;随着矿物演化程度的增加,蒙脱石逐渐向伊利石转化,转化过程中,蒙脱石层间水分子的逐渐排出引起页岩储层孔隙度增加,且在层间形成微孔隙和微裂隙;伊/蒙混层从无序状态变为有序状态,大量脱出层间水,而层间水变为自由水进入页岩固有的孔隙空间,并在地层压实作用下使页岩孔隙体积增大。页岩有机质生烃对孔隙有保护作用,成岩后期压实作用使页岩孔隙减小,但随着地层温度和压力达到页岩生油窗,有机质生烃作用生成的部分油气进入之前的孔隙,增加孔隙内部压力,减缓压实作用下孔隙体积的降低。     

Recreational value estimation of suburban leisure agriculture: a case study of the Qianjiangyue agritourism farm

As a form of economic and community development, agritourism has a strong and widespread appeal to all tourists. To explore the situation and value of agritourism in China, the Qianjiangyue agritourism farm located between Fuzhou City and Yongtai County was chosen to evaluate recreational values. The data was obtained from tourists and farm samples in Qianjiangyue agritourism farm by questionnaires. Two basic models including the zonal travel cost method (ZTCM) and the individual travel cost method (ITCM) were applied for data analysis. The recreational value estimation results obtained from ITCM and ZTCM showed that the total consumer surplus (CS) of the Qianjiangyue agritourism farm in 2011 was estimated at 54,533,300 CNY (8,894,682 US$) which was equal to a CS per tourist of 3029.63 CNY (494.15 US$), and the annual recreational value of agricultural landscapes per hm² was 361,078 CNY (58,893.82 US$). The average annual recreational value of agritourism farmland was 15.7 times of that from traditional farming, and 6 times of present land business income. This paper will be helpful for exploring and utilizing appropriate environmental resources in China.     

微电阻率成像测井双属性岩石相划分方法——以准噶尔盆地玛湖凹陷百口泉组为例

准噶尔盆地西北缘玛湖凹陷百口泉组发育大型缓坡背景下的粗粒扇三角洲沉积,岩性复杂,钻井取心主要集中于油气显示较好的井段,影响整个地层组岩石相的研究。在岩心资料的基础上,利用微电阻率成像测井技术,识别玛湖凹陷百口泉组扇三角洲10种岩性及5种沉积构造,提出微电阻率成像测井的双属性岩石相划分方案,包括12种砾岩岩石相、14种砂岩岩石相和2种泥岩岩石相,精细划分百口泉组全井段的岩石相。结果表明:块状层理小中砾岩、交错层理小中砾岩、交错层理细砾岩是储集层最主要的岩石相类型;块状层理泥岩较发育;百三段各类砾岩岩石相较少、泥岩和粉砂岩岩石相较多。该方法可为玛湖凹陷百口泉组扇三角洲沉积微相和沉积体系的研究提供参考。     

基于米兰科维奇理论的高频沉积旋回识别与对比——以准噶尔盆地玛湖凹陷百口泉组为例

由天体轨道周期性变化引起气候改变而被记录在沉积地层中的米兰科维奇旋回,具有时间域上的等时性特征,是实现高频沉积旋回等时划分与对比的有效途径。基于米兰科维奇理论,以准噶尔盆地玛湖凹陷百口泉组地层为研究对象,对3口井自然伽马和电阻率测井曲线进行频谱分析。将测井曲线经过滤波处理后提取出的短偏心率周期99.0ka和短斜率周期40.5ka的滤波曲线,作为五级层序沉积旋回和六级层序沉积旋回的参考曲线,对百口泉组地层进行高频沉积旋回的划分与对比,建立玛湖凹陷百口泉组地层沉积旋回对比格架。结果表明:百口泉组地层保存完整的米兰科维奇沉积旋回,旋回主要由偏心率(99.0ka)和斜率(40.5ka)周期控制,偏心率和斜率周期引起的地层厚度分别为6.49~7.05和2.56~2.98m,平均沉积速率为6.76cm/ka。该研究结果为测井曲线在高频地层层序识别与划分上的应用提供新的方法,为层序地层划分研究提供参考。     

Impacts of future climate change (2030-2059) on debris flow hazard: A case study in the Upper Minjiang River basin,China

An increase in extreme precipitation events due to future climate change will have a decisive influence on the formation of debris flows in earthquake-stricken areas. This paper aimed to describe the possible impacts of future climate change on debris flow hazards in the Upper Minjiang River basin in Northwest Sichuan of China, which was severely affected by the 2008 Wenchuan earthquake. The study area was divided into 1285 catchments, which were used as the basic assessment units for debris flow hazards. Based on the current understanding of the causes of debris flows, a binary logistic regression model was used to screen key factors based on local geologic, geomorphologic, soil, vegetation, and meteorological and climatic conditions. We used the weighted summation method to obtain a composite index for debris flow hazards, based on two weight allocation methods: Relative Degree Analysis and rough set theory. Our results showed that the assessment model using the rough set theory resulted in better accuracy. According to the bias corrected and downscaled daily climate model data, future annual precipitation (2030-2059) in the study area are expected to decrease, with an increasing number of heavy rainfall events. Under future climate change, areas with a high-level of debris flow hazard will be even more dangerous, and 5.9% more of the study area was categorized as having a high-level hazard. Future climate change will cause an increase in debris flow hazard levels for 128 catchments, accounting for 10.5% of the total area. In the coming few decades, attention should be paid not only to traditional areas with high-level of debris flow hazards, but also to those areas with an increased hazard level to improve their resilience to debris flow disasters.     

基于数字岩心技术的岩石孔渗特征研究: 以海外J油田孔隙型碳酸盐岩油藏为例

走向海外是解决我国能源安全问题的必由之路。但海外油气藏评价往往缺乏第一手岩心资料, 使得储层孔隙结构和渗流规律认识不清, 影响评价效果。以海外J油田孔隙型碳酸盐岩油藏为例, 应用数字岩心技术开展油气藏孔渗特征研究。①以不同流动单元的铸体薄片图像作为输入数据, 经过中值滤波和阈值分割预处理后, 基于马尔科夫链蒙特卡洛数值重构算法构建数字岩心; ②分析孔喉分布、孔喉连通性、孔隙度特征; ③基于格子玻尔兹曼模拟方法开展单相和油水两相流动模拟, 计算数字岩心的绝对渗透率和相对渗透率曲线。结果表明, 构建的三维数字岩心能够刻画不同流动单元孔隙型碳酸盐岩的孔喉半径分布及孔喉连通程度的差异化特征。数字岩心孔隙度与铸体薄片孔隙度吻合度高, 数字岩心渗透率与真实岩心渗透率存在较好的正相关关系, 且符合真实岩心所属的流动单元。油水两相稳态流动模拟计算的相对渗透率曲线体现了不同流动单元的两相渗流能力差异, 可作为数值模拟输入条件, 以及估算油藏采收率。数字岩心分析与物理实验结果吻合良好, 证明了该方法的可靠性。为岩心资料稀缺条件下油气藏表征和渗流特征分析提供新的思路, 对油气藏精细描述具有重要的参考价值。      

Analysis of comprehensive benefits of transforming slope farmland to terraces on the Loess Plateau: A case study of the Yangou Watershed in Northern Shaanxi Province, China

De-farming slope farmland has been an effective measure in recent years to improve environment and prevent soil and water loss on the Loess Plateau.There are different views about the defarming method,and also various de-farming patterns have been put into practice.This paper takes the Yangou Watershed in Shaanxi Province of China as a case for studying the comprehensive benefits of transforming slope farmland to terraces.Based on the day-by-day meteorological data of the Yan'an station in 2005 and the data...     

Significance of glacio-morphological factors in glacier retreat: a case study of part of Chenab basin,Himalaya

A study has been carried out in part of Chenab basin,Himalaya to understand the relationship between glacio-morphological factors and change in glacial area. Initially change in areal extent of glaciers was derived for two time frames(1962-2001/02 and 2001/02-2010/11). The study comprised of 324 glaciers for the monitoring period of 1962-2001/02 for,which 11% loss in glacial area was observed. Two hundred and thirty-eight glaciers were further monitored between 2001/02 and 2010/11. These glaciers showed an area loss of 1.1%. The annual deglaciation has been found to be higher during the period of 1962-2001/02 compared to 2001/02-2010/11. The spatial and temporal variability in deglaciation was also addressed usingglacio-morphic parameters. Area,length,percentage of debris cover,and various elevation parameters of glaciers were observed to have significant controls on relationships to the rate of glacial shrinkage. Largerarea and longer glaciers show a lower percentage of retreat than smaller and shorter ones. Moreover,glaciers located at lower altitudes and having gentle slopes show more area retreat. The results of area retreat in debris covered and debris free glaciers supports that the glaciers covered by debris retard ice melting at some extent. 158 glaciers were observed having no debris cover,and these exhibit 14% of loss in surface area. In glaciers having 40% debris cover,8% of deglaciation was observed. The glaciers located below equilibrium line altitude(ELA) have experienced 4.6% of deglaciation for the time frame 2001/02 – 2010/11 whereas it was found to be 1.1% for the glaciers occurring above ELA. However,theorientation of glaciers did not show any considerable influence on glacial change based on hypothesis.     

Effects of land-use types on soil organic carbon stocks: a case study across an altitudinal gradient within a farm-pastoral area on the eastern Qinghai-Tibetan Plateau,China

A crucial region for China's ‘Grain-forGreen Policy' is located within a traditional farmpastoral area, between 2000 to 3000 m above sea level, on the eastern Qinghai-Tibetan Plateau.However, the responses of soil organic carbon(SOC) to different land-use patterns in this region are unclear. Here, we determined the SOC(0–20 cm) content of grasslands and forests that are being converted from farmlands, as well as in abandoned arable land and arable land in this region. The factors influencing the reclaimed lands were analyzed along altitudes from 2030 to 3132 m. Our results showed that SOC content was higher for grassland and abandoned arable land than forest and arable land. The SOC content increased with the increase in altitude for total land-use patterns. Further, the grassland and abandoned arable land had higher SOC content than the forest with almost parallel trends along the increase in altitude. However, the proportion of regulated factors of altitude and species richness varied among forest, grassland, and abandoned arable land. Our results indicated that the land-use pattern of returning farmland to grassland and abandoned arable land was more effective in terms of the SOC storage in the superficial layer in this altitude range in the Qinghai-Tibetan Plateau, thereby being beneficial to optimizing land management in this region.     

Micromorphology and quality attributes of the loess derived soils affected by land use change: A case study in Ghapan watershed, Northern Iran

In order to study the effects of different land vegetative covers on soil quality attributes, a loess hill slope was selected in eastern Golestan Province, Ghapan watershed, Iran. Four profiles in four land uses, including Quercus natural forest; Pinus artificial forest; Cupressus artificial forest and a cultivated land, were studied. Results showed that MWD was significantly different in the studied land uses, and it varied between 1.6 mm in Quercus natural forest and o.31 mm in cultivated land use. The lowest CEC, microbial respiration rate and organic carbon were 28.4 cmol·kg^1, 177 μgCO2·g^-1·day^-1 and 1.32 % found in cultivated land use, respectively. The organic matter was considerably higher content in the forest areas than that of cultivated land use. The studies on soil profile development revealed that the natural forest soils were highly developed. The soils of the Quercus natural forest were classified as Calcic Haploxeralfs with a well developed argillie horizon unlike the cultivated soils which showed the minimum development and classified as Typic Xerorthents. The soils of the artificial forests had both mollic epipedons and were classified as Typic Calcixerolls with moderate profile development. Micromorphological studies revealed that argillic horizons had speckled and partly crystallitic b-fabric in the natural forest indicating the high landscape stability. In contrast, the crystallitic b-fabric of other land uses shows the absence of enough leaching of carbonate and the subsequent migration of clay particles indicating the unstable conditions and high soil erosion. Intense erosion of the surface horizons of cultivated land use has resulted in the outcropping of the subsurface carbonate rich horizons preventing soil development.     

西北内陆盆地浅层地下水温度场及动态类型:以酒泉东盆地为例

温度是地下水的固有属性,地下水温度场和动态特征是地下水流系统的外在表现。为揭示地下水开采等人类活动影响下西北内陆盆地浅层地下水温度场特征与地下水流系统的关系,基于多点位、长序列、高精度的地下水温度监测数据,在酒泉东盆地开展了地下水温度场及动态特征研究。结果表明：酒泉东盆地浅层地下水温度9.33～20.77℃不等,平均水温为13.54℃,自地下水补给区至排泄区,沿地下水径流方向,浅层地下水温度逐渐升高;循环深度相近的不同地下水流系统对比表明,浅层地下水温度与地下水动力条件呈负相关,地表水入渗补给大、水动力条件强的水流系统地下水平均温度低,入渗补给小、水动力条件弱的地下水平均温度高;浅层地下水温度动态受自然地下水循环和地下水开采等人类活动共同影响,从山前地下水补给区到中游绿洲区再到下游排泄区,浅部地下水温度动态可划分为4种基本类型,依次分别为河流补给型、水温稳定型、开采相关型、正弦波动型。     

EFFECTS OF AGRICULTURE RECLAMATION ON THE HYDROLOGIC CHARACTERISTICS IN THE SANJIANG PLAIN, CHINA

1 THE NATURAL ENVIRONMENTAL CHARACTERISTICS The Sanjiang Plain is located in the northeast of Heilongjiang Province, China. Russia borders this region in the north and east. Its total area is 1.088×107ha. The area of plain occupies 61.21％of the total land area and that of hill and mountain amounts to 38.79％of the total land area. It is not only one of the most important regions with large area of fresh water wetlands and with varieties of rare migratory waterfowls, but a…