Micromorphological Features of Old Cultivated and Modern Soils in Guanzhong Areas, Shaanxi Province, China

Using the data obtained from the LGT soil profile, this article attempts to illustrate the process of modem soil formation in the Guanzhong areas and its micromorphological features. The micromorphology is observed under a petrographic microscope, and its image is quantitatively measured by LEICAL Qwin 2.6 software. Micromorphological observations of the thin sections show that the assemblage of minerals in different horizons is very similar, which is mainly composed of Q and P1. However, there are obvious differences in C/F15μm ratio, mineral content, and coarse features. The pedofeatures is mainly composed of clay, calcite, and amorphous Fe. Ap horizon is characterized by abundant needleshaped secondary calcite, secondary clay, and earthworm fecal pellet. BC horizon is characterized by a large quantity of secondary calcite with various shapes. Bt1and Bt2 horizons are characterized by abundant clay hypocoatings and a small quantity of secondary calcite. All the results of this research suggest that Earth-cumulic Orthic Anthrosols consist of both the upper Ap horizon, which cause loessal dung and eolian dust deposition, and cultivation occurs simultaneously during the process of Ap horizon-formation, and the lower BC horizon, which is aeolian sedimentary at the time of relative aridity during late Holocene.

Comparison of Micromorphological Features of Two Agricultural Cultivated Soils in Guanzhong Areas, Shaanxi Province, China

By comparing micromorphological features of irrigated and non-irrigated soils in Guanzhong areas, China, this paper tries to illustrate the influences of farming management methods on the soil-forming process. The micromorphology was observed under a petrographic microscope and its image was quantificationally measured by Nikon NISBR 2.2 software. Both irrigated and non-irrigated soils have the same soil profile pattern, Ap1- AP2- BC, but the former has a more obvious profile dissimilation. The minerals assemblage of soil profiles A and B are very similar, which is mainly composed of Q and P1. Compared with non-irrigated soil, grains of irrigated soil remarkably decrease in length, area, eqdiameter, perimeter, elongation, roundness, and C/F10μm ratio; voids are characterized by more regular void shape and more smooth void wall; there is more abundant residual clay and small amount of illuvial clay. All results in this study suggest that the farming management method has influences on soil profile dissimilation and micromorphology. Agricultural irrigation could strengthen the degree of weathering, make smaller and rounder soil grains, cause a significant increase of residual clay and appearance of illuvial clay. But no significant change has been observed in the minerals assemblage of coarse grains.

A Preliminary Study on the Main Ridge Decoration of Buildings in Yuan,Ming,and Qing Dynasties in Guanzhong Area

The function of roof ridge ornament is irreplaceable in the facade modeling of traditional Chinese architecture.Taking the ornament in the Ming and Qing Dynasties in Guanzhong area as an example,this paper summarizes and analyzes the appearance characteristics,and internal cultural connotation of the ornament that is currently present in the Guanzhong area from the aspects of its decorative content,color,and grade indication.Further,make relevant discussions,hoping to supplement the research of ancient ornament.

Spatio-temporal analysis of cropland change in the Guanzhong area, China, from 1650 to 2016

As one of the most critical impact factors of global change,historical land-use change is an indispensable input in climate and environment simulations.To better understand the cropland change in the Guanzhong area,gazetteers,statistics,and survey data were collected as data sources.Methods of registered tax-paying cropland data collection,selection of time points,and data interpolation and calibration were used to reconstruct changes in the cropland area.The cropland area data at the county level were allocated to 1 km×1 km grid cells.The total cropland area in the Guanzhong area was influenced by changes in population,wars,natural disasters,and land-use types,and it fluctuated from 1650 to 2016.From 1780 to 1830,the cropland expanded in the northern and western parts of Guanzhong area,and the cropland in the north of Qinling Mountains increased slightly.The spatial pattern of cropland reached its maximum range in 1980,and the cropland area declined in the whole study area,especially in the cities of Xi’an and Xianyang in 2016.The comparison between HYDE 3.2 and the data obtained in this study showed that the grid cells of HYDE 3.2 exhibit lower values of cropland area fractions in the Guanzhong Basin and higher values in high-altitude areas around the Guanzhong Basin as compared to those in this study.

Phenological records in Guanzhong Area in central China between 600 and 902 AD as proxy for winter half-year temperature reconstruction

Phenological data obtained from historical documents constitute highly important ecological evidence for the pre-instrumental period, and can be used in analyzing climatic change in history. In this study, 87 phenological records about seasonality of non-biological events(e.g., first frost date), agriculture and ornamental plants(e.g., first flowering date) over 77 years were extracted from historical documents from the Sui and Tang dynasties in China to reconstruct the winter half-year(from October to next April) temperatures in the Guanzhong Area(located in central China) from 600 to 902 AD. Transfer functions between temperature and phenophases with significant correlations were established by using modern observation data. Temperatures from the study period were reconstructed by applying the transfer functions to historical phenological data. The reconstruction indicates that the winter half-year temperatures during 600–902 AD were 0.23°C higher than the reference period(1961–1990). The temperature changed with two distinct stages. During the 600s–800s, temperatures were approximately 0.38°C higher than at present but then temperatures decreased in the subsequent period(800–902 AD). These results are similar to ones from previous studies on the mean temperature and the divisions between warm and cold periods during the study period, though differences were found in the degree of warmness/coldness. This reconstruction provides a valuable contribution to a better understanding of climatic variability during the Sui and Tang dynasties in China.

Study on Architectural Concept of Environmental Adaptability of Vernacular Dwellings in Guanzhong-Tianshui Area

Vernacular dwellings are organic products adaptive to local climate and other natural conditions. From the perspective of climatic and geographical features, this study analyzed spatial layouts, outer appearance, courtyard layout and material structure of vernacular dwellings in Guanzhong-Tianshui area, and refined the ecological concepts and technologies adaptive to local environment. Vernacular dwellings are expected to develop sustainably in the evolution of natural environment, and adapt to the development needs of local human settlements.

基于景观指数的关中地区耕地细碎化程度的时空变迁及其驱动因素

[目的]优化陕西耕地细碎化治理,协调粮食需求增长与环境约束之间的矛盾,维护地区粮食安全和促进农业现代化发展。[方法]以关中地区为研究区,以土地利用数据和其他自然经济数据为基础,运用洛伦兹曲线、变异系数法、景观指数、空间自相关等方法构建耕地细碎化评价模型以探索关中地区耕地细碎化(Cultivated Land Fragmentation,简称CLF)的时空变迁,并利用地理探测器对区内CLF进行了驱动力分析。[结果](1)关中地区耕地资源空间分布相对均衡,耕地专业化程度保持较高水平。(2)关中地区的CLF程度变化时空差异显著,CLF程度整体呈现下降态势,但部分地区CLF程度呈增减并存趋势,整体呈现东低西高的态势。(3)关中地区CLF时空分化受多种因素影响,社会经济因素的综合影响明显强于自然因素,其中海拔高度、人口密度、人均耕地面积和地区总产值GDP为主要影响因素;因子间的交互作用效应强于单因子,以双因子增强和非线性增强为主。[结论]关中地区耕地细碎化问题在20年间得到了一定程度的改善,但呈现出较大的地区差异,应进一步在社会经济因素方面对耕地细碎化现象加强综合治理,以推动关中地区农业机械化、现代化发展。

基于多因素正交实验的关中民居节能优化分析

为解决陕西关中地区民居建筑围护结构热工性能不佳、采暖效率低的问题,本文以关中典型民居为研究对象,从建筑外围护结构和窗墙比方面展开关中民居节能优化分析。结合现场测试调研数据,通过DesigBuilder软件模拟能耗,探究围护结构构造和窗墙比大小对关中民居建筑热负荷、冷负荷、全生命周期投资收益比的影响,采用多因素正交实验方法耦合分析各优化方案的节能性与经济性,选出最适宜的综合节能策略。结果表明关中民居最佳节能优化策略为外墙加设80 mm厚EPS保温层、屋顶加设60 mm厚XPS保温层、外窗改用普通中空5+9A+5玻璃、北向窗墙比0.1、南向窗墙比0.3。优化后关中典型民居节能61.98%,冬季典型气象日室内平均温度上升2.78℃。

陕西省关中地区桃园土壤肥力状况分析与评价

【目的】调查陕西省关中地区桃园土壤肥力状况,旨在为该区桃园土壤养分管理和施肥提供科学依据。【方法】以咸阳、宝鸡、铜川和渭南4市共24个桃园0~40 cm土层土壤为研究对象,对土壤容重、孔隙度、pH及有机质、全氮、有效磷、有效钾、硝态氮和铵态氮含量进行测定分析并评价。【结果】陕西省关中地区桃园0~20 cm土层土壤容重和孔隙度处于适宜范围,而在>20~40 cm土层,咸阳地区土壤容重较高,宝鸡地区土壤容重较高且孔隙度较低,均超出适宜范围;研究区土壤pH平均值为8.1,除宝鸡桃园土壤pH在6.4~6.9之间外,其余地区桃园均为碱性土壤,pH在8.2~9.0之间;陕西省关中地区土壤肥力总体水平不高,土壤有机质最为缺乏,在0~40 cm土层中,66.7%以上的桃园土壤有机质和全氮含量均处于缺乏水平;0~40 cm土壤有效钾含量均处于适宜或丰富水平,>20~40 cm土层的土壤有效磷含量处于缺乏水平;关中地区速效氮平均含量(w,后同)为10.8 mg·kg^(-1),处于缺乏状态,其中渭南的桃园土壤氨态氮和硝态氮含量最高,0~40 cm土层平均值分别为5.1 mg·kg^(-1),13.6 mg·kg^(-1),咸阳、铜川地区次之,宝鸡地区最低。【结论】陕西省关中地区桃园土壤有机质含量低,肥力低,应采取综合措施调节土壤通气保水性、降低碱度并培肥土壤。

关中地区人类活动强度与地表温度的时空关联特征及其驱动作用

人类活动对全球温度升高的促进作用愈加明显,如何科学衡量人类活动强度并探究其与地表温度的时空关联性成为当前研究热题。以关中地区为例,整合人口密度、地区生产总值、夜间灯光强度、建设用地面积比例、电量消耗5个指标表征人类活动强度,分析关中地区人类活动强度与地表温度时空变化规律,探究人类活动强度与地表温度关联性及其驱动作用。结果表明:(1)2001—2020年关中地区平均地表高温、低温区域分别呈现总体增大、减少的趋势,地表高温区域范围不断扩大。(2)2000—2020年关中地区的人类活动强度逐渐增加,特别是在各地级市的市辖区和主要居民点,高强度区域范围不断扩大,而低强度区域主要位于秦岭山区。(3)2000—2020年关中地区人类活动强度与地表温度呈显著正相关性和空间上的集聚性,正相关区域面积呈现增大趋势,主要由不显著及负相关转化为正相关区域,高-高类型集聚区主要分布在各城市主城区,低-低类型集聚区主要分布在秦岭山区。(4)影响地表温度的人类活动强度指标中,夜间灯光强度、人口密度、建设用地面积比例对地表温度的驱动作用最为显著;且夜间灯光强度与建设用地面积比例、人口密度与建设用地面积比例交互作用对地表温度的解释力最强。

关中地区中深层地埋管换热器长期运行性能研究

我国关中地区地热资源丰富,中深层地热能供暖技术具有广阔的应用前景,而地质参数是影响中深层地埋管供暖系统性能的决定性因素。针对陕西关中地区中深层地埋管供暖性能展开研究,通过梳理关中地区咸阳市兴平市、咸阳市渭城区、西安市高陵区、西安市鄠邑区、西安市长安区5个典型区域的地质参数,结合典型地埋管结构参数,对长期运行下的换热器性能及热作用半径变化规律进行模拟计算。结果表明,不同地区换热器运行之初的性能变化较为显著,但均在经过5 a左右运行后趋于稳定。地埋管深度从2000 m增至2500 m时,出口水温有着明显的提升,同一时刻下出口水温的涨幅可达8%,各采暖季末的出口水温随深度增加的变化更为显著。由于长期运行,年平均取热功率呈现下降趋势,20 a内的总降幅为11%~12%;随着换热器埋深的增加,取热功率涨幅可达41.41%~53.23%。热作用半径受埋深的影响不显著,不同埋深管道运行20 a后的井底最大热作用半径均在50 m左右;土壤温度受与换热器距离及运行时长的影响更大,距离20 m以内的土壤温度呈现明显的波动下降趋势,而距离在60 m以外的土壤温度在20 a的运行期内降幅很小。此外,由于具有大厚度新近系张家坡组(N2z)和新近系蓝田-灞河组(N2l+b)的地质条件,西安市鄠邑区、高陵区以及咸阳市兴平市等地区地埋管的出口水温、取热功率较高,更适宜开展中深层地热能供暖利用。研究成果有望为关中地区中深层地热能高效利用提供参考。

Three-dimensional crustal deformation before and after the Wenchuan earthquake in Guanzhong and adjacent regions

The recent plethora of GPS observations compensates for the 20-year-old lack in vertical displacement data for the Guanzhong region. The 2001—2007 three-dimensional（3D） crustal deformation data suggest regional movement with a horizontal velocity of 3—7 mm/a,predominantly from SSE in the west to SE in the east, and vertical inherited movement with velocity of -7 mm/a to 4 mm/a. After the Wenchuan earthquake, the GPS data suggest that the effect of the earthquake on the regional deformation is greater in the west than the east.The horizontal displacement increased during 2007—2008; however, the reverse was observed in 2008—2009. The vertical displacement in the western part of the region increased in 2008 and has been gradually returning to normal since 2009; however, in the eastern part,the effect of the earthquake remains.

基于数学模型的小麦品种中麦895在关中灌区高产栽培研究

以两因素二次正交回归方案设计试验,应用DPS软件,以产量(Y)为目标函数,将播期(X_(1))、播量(X_(2))做为因素进行研究,研究高产小麦品种中麦895在关中灌区的高产栽培技术。结果表明,中麦895在关中灌区适宜的播期和播量分别为,播期10月5~10日,播量为260.75~343.93万基本苗/hm^(2)。

适应使用者新需求的关中乡村民宿空间更新设计研究

乡村“民宿热”后,以农户自建房改造类为主的民宿建筑因空间品质等问题陷入经营困境,严重阻碍了乡村休闲旅游可持续发展。地方村民作为此类民宿的核心魅力,探讨使用者与空间的作用关系是推动民宿空间更新的重点。以关中地区为例,通过典型案例入户调研民宿使用者——农户与游客的行为需求现状,总结民宿内农户自用空间、客房空间、游客休闲空间以及主客共享空间的利用特征与问题,从而提出功能构成与组织优化、空间改造设计方法。

关中地区中深层热储岩石学特征及潜在损害因素分析

为搞清关中地区中深层热储的潜在损害因素,以区内蓝田灞河组热储岩样为研究对象,采用铸体薄片、粒度分析、扫描电镜、CT扫描及X衍射等手段,在岩性分类的基础上,开展填隙物、物性及孔隙结构的研究,着重分析敏感性矿物、储渗空间与热储损害的关系。结果表明,各类热储岩石的黏土矿物质量分数从高到低依次为:粉砂岩>细砂岩>中砂岩>砂砾岩。热储层岩石物性分布范围较宽,渗透率与孔隙度存在一定的正相关关系。热储岩石的物性按岩性从好到差依次为:砂砾岩>中砂岩>细砂岩。杂基质量分数越高,热储岩石的物性越差。各类热储岩石中较大尺寸的孔喉对渗透率的贡献大,热储岩石中的地层微粒尤其是黏土矿物,在与外界流体接触或所处环境改变时,很容易发生分散、运移,对储层造成损害;热储岩石胶结疏松的特征加剧了热储岩石自身的微粒运移。

关中灌区小麦茎基腐病及地下害虫的化学防治试验

为探索关中灌区小麦茎基腐病及麦田地下害虫的化学防治方法。运用绿色环保型杀菌、杀虫剂的不同组合,以试验的方法和拌种的技术,探索合适的农药品种及配伍。结果表明:杀菌+杀虫复配剂,能有效抑制小麦茎基腐病病菌的浸染、发展,控制地下害虫的危害。关中罐区的小麦茎基腐病及麦田地下害虫,可以通过化学方法得到较好的防治,进而达到增产的目的。

未来气候条件下秸秆还田和氮肥种类对夏玉米产量及土壤氨挥发的影响

【目的】秸秆还田配施氮肥可以提高作物生产力,但在气候变化条件下,不同管理措施对夏玉米农田氮素利用存在很大的不确定性。明确在未来气候条件下秸秆还田与氮肥种类对夏玉米产量和土壤氨挥发的影响,以应对气候变化。【方法】利用DNDC模型预测未来不同情景下,秸秆还田和不同氮肥种类对关中地区夏玉米产量和土壤氨挥发的影响。通过田间土壤温度、水分、产量和土壤氨挥发累积量试验数据的验证,DNDC模型可以很好地模拟未来气候条件下不同处理的作物产量和土壤氨挥发累积量。【结果】模拟和实测结果均表明,在当前气候条件下秸秆还田会提高作物产量并促进土壤氨挥发,稳定性氮肥与普通尿素相比对产量无显著影响但会显著减少土壤氨挥发累积量。敏感性分析表明,作物产量与土壤氨挥发累积量均对施氮量最敏感。在RCP4.5排放情景下,单施稳定性氮肥(NF1)和单施尿素(NF2)分别在2050s-2090s和2070s-2090s产量显著降低,秸秆配施稳定性氮肥(SF1)和秸秆配施尿素(SF2)均在2050s-2090s产量显著升高;在RCP8.5排放情景下,单施稳定性氮肥(NF1)在2070s-2090s产量显著降低,单施尿素(NF2)产量无显著变化,秸秆配施稳定性氮肥(SF1)和秸秆配施尿素(SF2)均在2050s-2090s产量显著升高。单施稳定性氮肥(NF1)在RCP4.5排放情景下的2050s-2090s和在RCP8.5排放情景下2030s-2090s土壤氨挥发累积量与当前气候条件相比显著提高,其余各处理在不同排放情景下未来各时期土壤氨挥发累积量与当前气候条件相比均显著降低。【结论】DNDC预测结果表明,在关中地区未来气温和CO_(2)浓度升高以及降水变化的气候条件下,秸秆还田配施稳定性氮肥会显著提高夏玉米产量并降低土壤氨挥发累积量,是最佳的高产减排农田管理方案,可为应对气候变化及合理使用秸秆和氮肥提供理论基础。

基于AquaCrop模型的玉米需水和降水匹配度变化特征研究

雨热同期为我国大部分地区农业生产提供了充足的水热资源,但从需水机理的角度评估作物生长和降水过程匹配度的变化特征还有待深入。基于AquaCrop模型模拟了关中地区1978-2017年夏玉米生育期内需水量、灌溉需水量、有效降水量和产量的变化特征,并在充分考虑玉米不同生育阶段对水分需求程度差异的基础上,分析了作物需水与降水匹配度的变化特征。结果表明:关中地区玉米生育期内累积降雨量变化幅度相对较小,但降水过程明显后移,且更多的以暴雨的形式发生;玉米生育期内需水量和灌溉需水量均呈现明显的增加趋势,增加幅度分别为4.10 mm/10a和13.38 mm/10a,而有效降水量则以-10.28 mm/10a的速率减小;玉米生育期内需水与降水的平均匹配度为58%,且整体以-2.7%/10a的速率下降。上述结果表明关中地区降水模式越来越难以满足夏玉米的水分需求,延迟播种可作为提高作物需水与降水匹配度的应对措施之一。

关中乡村自保温多孔砖性能优化设计研究

自保温墙体作为一种适应于乡村推广的节能技术,其热工性能主要取决于自保温墙材的性能。以标准为导向,以自保温多孔砖为研究对象,采用正交实验法、热分析模拟法、理论计算法对适应于关中乡村使用的自保温多孔砖的热性能进行优化设计研究。结果表明,对自保温多孔砖孔洞相关参数进行优化设计时,应结合孔洞的排列方式,重点考虑垂直于热流面的矩形孔数量、矩形孔长宽比以及孔洞数量这3个因素的交互作用,孔洞率及孔洞排数为辅助参数进行配合设计。

陕西关中土壤富硒标准研究与探讨——以小麦为例

建立陕西省富硒小麦产地土壤硒阈值不仅关系到天然富硒小麦精益化、精细化、精确化生产,更能够提高富硒土地利用效率,促进陕西富硒产业发展。本文以1∶25万土地质量地球化学调查数据为基础,依托陕西省近年来采集的544组土壤及其对应的小麦籽实样品硒含量数据,基于关中地区表层土壤硒地球化学异常下限和小麦—土壤隶属函数结果,提出以0.27×10^(-6)作为陕西省富硒小麦产地土壤硒阈值。实证研究发现,采用随机抽样得到的验证集的小麦富硒率达到83.78%,第三方检验的富硒率高达87.14%,以该阈值圈定的土地生产出的小麦能够满足中国营养学会规定的硒推荐摄入量(60μg/d),土地面积约为1500 km^(2)(225万亩),比按0.3×10^(-6)圈出的富硒土地增加了640 km^(2)(96万亩)。由此可见,按照农作物种类有针对性地界定富硒土壤界限值,能够较大程度地提高富硒土地利用效率,促进富硒产业发展,为制定陕西省富硒土壤标准提供科学依据。