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1. chinaXiv:202110.00048 [pdf]

1985—2016 年民勤地下水位及储变量动态特征分析

魏士禹
Subjects: Geosciences >> Hydrology

民勤地处两大沙漠之间,近几十年地下水位持续下降,水资源严重短缺。为正确指导当地 地下水合理开发利用和生态恢复,剖析多年来的地下水开发利用过程和地下水动态变化特征尤为 重要。在收集并分析了 138 眼监测井水位数据的基础上,划定出民勤县地下水动态类型分区,并利 用克里金插值法绘制了民勤盆地 1985—2016 年逐年地下水流场和水位变幅图,采用网格法计算出 地下水多年储变量。同时,探究了民勤盆地地下水位的影响因素,得到回归方程并估算地下水可 开采量。结果表明:(1)民勤县地下水位动态类型可划分为开采型、灌溉入渗-开采型、河流入渗- 开采型和径流型。(2)民勤盆地地下水位多年来整体下降,其中灌区下降明显,最大降幅为 22 m,沙 漠区略有下降,地下水多年累计亏损 24.45×108 m3。(3)石羊河综合治理后水位下降明显减缓并出 现局部回升,部分年份储变量为正。(4)明确地下水动态主要影响因素为开采量和地表引水量。将 地下水量变化过程划分为迅速下降期(1985—2000 年)、稳定下降期(2001—2006 年)、治理期 (2007—2009 年)和平稳/上升期(2010—2016 年)。(5)在现状地表供水情况下红崖山灌区地下水可 开采量约 0.61×108 m3·d-1。

submitted time 2021-10-10 From cooperative journals:《干旱区地理》 Hits278Downloads4 Comment 0

2. chinaXiv:202108.00007 [pdf]

Size- and leaf age-dependent effects on the photosynthetic and physiological responses of Artemisia ordosica to drought stress

WANG Chunyuan; YU Minghan; DING Guodong; GAO Guanglei; ZHANG Linlin; HE Yingying; LIU Wei
Subjects: Geosciences >> Geography

Drought is one of the most significant natural disasters in the arid and semi-arid areas of China. Populations or plant organs often differ in their responses to drought and other adversities at different growth stages. At present, little is known about the size- and leaf age-dependent differences in the mechanisms of shrub-related drought resistance in the deserts of China. Here, we evaluated the photosynthetic and physiological responses of Artemisia ordosica Krasch. to drought stress using a field experiment in Mu Us Sandy Land, Ningxia Hui Autonomous Region, China in 2018. Rainfall was manipulated by installing outdoor shelters, with four rainfall treatments applied to 12 plots (5 m×5 m). There were four rainfall levels, including a control and rainfall reductions of 30%, 50% and 70%, each with three replications. Taking individual crown size as the dividing basis, we measured the responses of A. ordosica photosynthetic and physiological responses to drought at different growth stages, i.e., large-sized (>0.5 m2) and small-sized (≤0.5 m2) plants. The leaves of A. ordosica were divided into old leaves and young leaves for separate measurement. Results showed that: (1) under drought stress, the transfer efficiency of light energy captured by antenna pigments to the photosystem II (PSII) reaction center decreased, and the heat dissipation capacity increased simultaneously. To resist the photosynthetic system damage caused by drought, A. ordosica enhanced its free radical scavenging capacity by activating its antioxidant enzyme system; and (2) growth stage and leaf age had effects on the reaction of the photosynthetic system to drought. Small A. ordosica plants could not withstand severe drought stress (70% rainfall reduction), whereas large A. ordosica individuals could absorb deep soil water to ensure their survival in severe drought stressed condition. Under 30% and 50% rainfall reduction conditions, young leaves had a greater ability to resist drought than old leaves, whereas the latter were more resistant to severe drought stress. The response of A. ordosica photosynthetic system reflected the trade-off at different growth stages and leaf ages of photosynthetic production under different degrees of drought. This study provides a more comprehensive and systematic perspective for understanding the drought resistance mechanisms of desert plants.

submitted time 2021-08-06 From cooperative journals:《Journal of Arid Land》 Hits2354Downloads173 Comment 0

3. chinaXiv:202108.00032 [pdf]

半干旱区煤化工高含盐废水自然蒸发规律研究

郭云彤; 邵景力
Subjects: Geosciences >> Atmospheric Sciences

本研究提出了 1 种选定特定区域可以代表气象因素影响的蒸发模型(公式)的实验方法,通 过结合气象因子分析,将淡水的理论蒸发量与实际蒸发量进行对比,选定合理的蒸发模型,并结合 对不同溶解性总固体(TDS)含盐废水蒸发实验的结果对蒸发模型进行了改进,使其适用于含盐废 水蒸发量的计算,以此为企业在蒸发塘的建设阶段及运行、管理过程中提供理论依据。研究表明: 在实验时段,蒸发与水面净辐射、气温呈正相关,与湿度呈负相关,与风速的相关性不显著;而从灰 色关联度来看,气象因子对蒸发的影响程度为:水面净辐射>气温>风速>湿度;实验时段童宏良公 式计算的淡水理论蒸发量为 205.76 mm,为最接近当地的实际蒸发量 205.51 mm,最能代表当地气 象因素对水面蒸发的影响;而相对蒸发率和反映溶液组成变化的 TDS 大致呈线性相关,R2 达 0.95, 在此基础上确定了适宜当地估算含盐废水蒸发量的公式。本研究还从气温影响及溶液成分的角 度对相对蒸发率进行讨论,认为实验值与蒸发塘实际记录值的差距是由于气温引起溶液饱和度下 降导致的,而理论值与实验值的差距则是由于在计算时将含盐废水原液作为理想溶液,并未考虑 溶液中各组分分子间的相互作用力。因此,蒸发塘选址时应注意当地的气象因素,且在蒸发塘处 理含盐废水时,应及时对蒸发塘内的析出物进行处理,避免蒸发过程中 TDS 增大对蒸发的影响。

submitted time 2021-08-01 From cooperative journals:《干旱区地理》 Hits70Downloads43 Comment 0

4. chinaXiv:202106.00044 [pdf]

气候变化和人类活动对锡林郭勒草原植被覆盖度的影响

屈莹波; 赵媛媛
Subjects: Geosciences >> Geography

基于遥感、气象及统计数据,采用线性趋势法和残差分析法,在不同时空尺度上监测1982—2018年锡林郭勒草原草地植被覆盖度动态,量化气候变化和人类活动对植被变化的贡献率。结果表明:1982—2018年,锡林郭勒草原植被覆盖度及变化具有明显的空间异质性,草甸草原覆盖度呈显著增加趋势(P<0.01),荒漠草原覆盖度呈显著减少趋势(P<0.01)。2000年为旗县草地覆盖度变化的主要节点。人类活动是锡林郭勒草原植被动态的主导因素,研究区多年人类活动因素的综合贡献率为65.06%。中东部和南部部分区域植被在人类积极作用下得到了显著改善,但西部和北部荒漠草原区的植被仍然呈现退化趋势。建议加大荒漠草原区生态政策实施力度以保障草地生态系统的可持续性。

submitted time 2021-06-13 From cooperative journals:《干旱区研究》 Hits390Downloads251 Comment 0

5. chinaXiv:202106.00008 [pdf]

Vegetation dynamics of coal mining city in an arid desert region of Northwest China from 2000 to 2019

ZHOU Siyuan; DUAN Yufeng; ZHANG Yuxiu; GUO Jinjin
Subjects: Geosciences >> Geography

Coal mining has led to serious ecological damages in arid desert region of Northwest China. However, effects of climatic factor and mining activity on vegetation dynamics and plant diversity in this region remain unknown. Wuhai City located in the arid desert region of Northwest China is an industrial city and dominated by coal mining. Based on Landsat data and field investigation in Wuhai City, we analyzed the vegetation dynamics and the relationships with climate factors, coal mining activity and ecological restoration projects from 2000 to 2019. Results showed that vegetation in Wuhai City mostly consisted of desert plants, such as Caragana microphylla, Tetraena mongolica and Achnatherum splendens. And the vegetation fractional coverage (VFC) and greenness rate of change (GRC) showed that vegetation was slightly improved during the study period. Normalized difference vegetation index (NDVI) was positively correlated with annual mean precipitation, relative humidity and annual mean temperature, indicating that these climate factors might play important roles in the improved vegetation. Vegetation coverage and plant diversity around the coal mining area were reduced by coal mining, while the implementation of ecological restoration projects improved the vegetation coverage and plant diversity. Our results suggested that vegetation in the arid desert region was mainly affected by climate factors, and the implementation of ecological restoration projects could mitigate the impacts of coal mining on vegetation and ecological environment.

submitted time 2021-06-04 From cooperative journals:《Journal of Arid Land》 Hits5145Downloads623 Comment 0

6. chinaXiv:202106.00014 [pdf]

Quantification of groundwater recharge and evapotranspiration along a semi-arid wetland transect using diurnal water table fluctuations

JIA Wuhui; YIN Lihe; ZHANG Maosheng; ZHANG Xinxin; ZHANG Jun; TANG Xiaoping; DONG Jiaqiu
Subjects: Geosciences >> Geography

Groundwater is a vital water resource in arid and semi-arid areas. Diurnal groundwater table fluctuations are widely used to quantify rainfall recharge and groundwater evapotranspiration (ETg). To assess groundwater resources for sustainable use, we estimated groundwater recharge and ETg using the diurnal water table fluctuations at three sites along a section with different depths to water table (DWT) within a wetland of the Mukai Lake in the Ordos Plateau, Northwest China. The water table level was monitored at an hourly resolution using a Keller DCX-22A data logger that measured both the total pressure and barometric pressure, so that the effect of barometric pressure could be removed. At this study site, a rapid water table response to rainfall was observed in two shallow wells (i.e., Obs1 and Obs2), at which diurnal water table fluctuations were also observed over the study period during rainless days, indicating that the main factors influencing water table variation are rainfall and ETg. However, at the deep-water table site (Obs3), the groundwater level only reacted to the heaviest rainfalls and showed no diurnal variations. Groundwater recharge and ETg were quantified for the entire hydrological year (June 2017–June 2018) using the water table fluctuation method and the Loheide method, respectively, with depth-dependent specific yields. The results show that the total annual groundwater recharge was approximately 207 mm, accounting for 52% of rainfall at Obs1, while groundwater recharge was approximately 250 and 21 mm at Obs2 and Obs3, accounting for 63% and 5% of rainfall, respectively. In addition, the rates of groundwater recharge were mainly determined by rainfall intensity and DWT. The daily mean ETg at Obs1 and Obs2 over the study period was 4.3 and 2.5 mm, respectively, and the main determining factors were DWT and net radiation.

submitted time 2021-06-04 From cooperative journals:《Journal of Arid Land》 Hits2967Downloads350 Comment 0

7. chinaXiv:202102.00068 [pdf]

Spatiotemporal patterns of the forage-livestock balance in the Xilin Gol steppe, China: implications for sustainably utilizing grassland-ecosystem services

QU Yingbo; ZHAO Yuanyuan; DING Guodong; CHI Wenfeng; GAO Guanglei
Subjects: Geosciences >> Geography

Understanding the spatiotemporal patterns of the forage-livestock balance is imperative for regionally arranging animal husbandry production while ensuring sustainable grassland-ecosystem service use. The Xilin Gol steppe is an important native grassland resource in Inner Mongolia Autonomous Region, China. This study aimed to elucidate the dynamics of the forage-livestock balance in the Xilin Gol steppe during the period 2000–2015. We evaluated the forage production and corresponding livestock carrying capacity (LCC) in the growing seasons of 2000–2015 using remote sensing data and field surveys. The spatiotemporal patterns of the forage-livestock balance were then assessed at regional, city (including city, county and banner), and village scales using statistical and household survey data. The results showed that both forage production and LCC decreased in the Xilin Gol steppe from east to west. During the period 2000–2015, the regional average forage production and corresponding LCC fluctuated without following a distinct trend, but were consistent with the variations in precipitation. The forage-livestock balance varied with time, space, and scale. At the regional scale, steppes were overgrazed in the early 2000s, but a forage-livestock balance or even grazing potential was achieved in other years. At the city scale, approximately half of the region exhibited a "forage-livestock balance" since 2000. However, about half of the region still experienced overgrazing, which mainly located in the southwest sandy zones. Such changes may have been affected by the variations in grassland quality, forage production, compensation payment, and so on. We suggest a location-specific management scheme for grazing constraints, ecological compensation payment, and industry development to aid in harmonizing animal husbandry and environmental restoration, while promoting sustainable development goals by 2030.

submitted time 2021-02-10 From cooperative journals:《Journal of Arid Land》 Hits883Downloads469 Comment 0

8. chinaXiv:202101.00017 [pdf]

基于遥感的银川市建成区城市扩展及其热环境变化分析

张晓东
Subjects: Geosciences >> Geography

为研究银川市城市建成区扩展对热环境的影响,基于 1989、1999、2010 年和 2017 年 Landsat 系列遥感数据,采用建筑用地指数(IBI)提取 4 个年份的城市建成区信息,获取了城市形态演化指 标,利用热红外波段反演不同年份的地表温度;在此基础上,分析了城市扩展和热环境变化的时空 演变特征,探讨了城市扩展和热环境之间的响应关系。结果表明:(1)1989—2017 年银川市城市建 成区扩展面积达 506.13 km2,各时期的扩展速度和扩展强度差异明显,城市扩展具有“缓慢—快速—稳步”的阶段性特征,城市空间形态趋于紧凑化,向着稳定状态发展,城市整体向东部和北部扩 展,重心整体向东北方向迁移约 5.54 km。(2)热岛范围随着城市扩展不断扩大,较高温区域所占热 岛比例呈先减小后增加的趋势,高温和特高温占比表现出先增加后减小的特征,热岛强度逐渐向 较高温区转移,城市热岛效应得到缓解;热岛空间分布显示,热岛逐渐由兴庆区老城区蔓延至贺兰 县和西夏区,且兴庆区热岛逐渐演化为相互独立的小次级热岛,强度有所降低;28 a 间银川市城市 热岛比例指数(URI)表现出先上升后下降的特征,整体呈上升趋势。(3)热岛区域在空间分布和扩 展方向上与城市扩展具有较高的一致性,城镇用地、公交建设用地和裸地能促进地表温度升高,而 草地和水体能够降低地表温度,公园绿地和水体能有效缓解银川市城市热岛效应且后者对降低城 市地表温度的效果要好于前者。

submitted time 2021-01-07 From cooperative journals:《干旱区地理》 Hits549Downloads332 Comment 0

9. chinaXiv:202011.00128 [pdf]

Degradation leads to dramatic decrease in topsoil but not subsoil root biomass in an alpine meadow on the Tibetan Plateau, China

ZHANG,Zhenchao; LIU,Miao; SUN,Jian; WEI,Tianxing
Subjects: Geosciences >> Geography

Understanding the effects of degradation on belowground biomass (BGB) is essential for assessment of carbon budget of the alpine meadow ecosystem on the Tibetan Plateau, China. This ecosystem has been undergoing serious degradation owing to climate change and anthropogenic activities. This study examined the response of the vertical distribution of plant BGB to degradation and explored the underlying mechanisms in an alpine meadow on the Tibetan Plateau. A field survey was conducted in an alpine meadow with seven sequential degrees of degradation in the Zoige Plateau on the Tibetan Plateau during the peak growing season of 2018. We measured aboveground biomass (AGB), BGB, soil water content (SWC), soil bulk density (SBD), soil compaction (SCOM), soil organic carbon (SOC), soil total nitrogen (STN), soil total phosphorus (STP), soil available nitrogen (SAN), and soil available phosphorus (STP) in the 0–30 cm soil layers. Our results show that degradation dramatically decreased the BGB in the 0–10 cm soil layer (BGB0–10) but slightly increased the subsoil BGB. The main reason may be that the physical-chemical properties of surface soil were more sensitive to degradation than those of subsoil, as indicated by the remarked positive associations of the trade-off value of BGB0–10 with SWC, SCOM, SOC, STN, SAN, and STP, as well as the negative correlation between the trade-off value of BGB0–10 and SBD in the soil layer of 0–10 cm. In addition, an increase in the proportion of forbs with increasing degradation degree directly affected the BGB vertical distribution. The findings suggest that the decrease in the trade-off value of BGB0–10 in response to degradation might be an adaptive strategy for the degradation-induced drought and infertile soil conditions. This study can provide theoretical support for assessing the effects of degradation on the carbon budget and sustainable development in the alpine meadow ecosystem on the Tibetan Plateau as well as other similar ecosystems in the world.

submitted time 2020-11-25 From cooperative journals:《Journal of Arid Land》 Hits2816Downloads643 Comment 0

10. chinaXiv:202010.00030 [pdf]

Effect of vegetation on soil bacteria and their potential functions for ecological restoration in the Hulun Buir Sandy Land, China

YAN,Ru; FENG,Wei
Subjects: Geosciences >> History of Geosciences

To date, much of research on revegetation has focused on soil microorganisms due to their contributions in the formation of soil and soil remediation process. However, little is known about the soil bacteria and their functions respond to the diverse vegetational types in the process of vegetation restoration. Effects of dominated vegetation, i.e., Artemisia halodendron Turcz Ex Bess, Caragana microphylla Lam., Hedysarum fruticosum Pall. and Pinus sylvestris L. on bacterial community structures and their potential functions in the Hulun Buir Sandy Land, China were determined using high-throughput 16S rRNA gene sequencing and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) in 2015. Although the dominant phyla of soil bacterial community among different types of vegetation, including Proteobacteria, Actinobacteria, Acidobacteria, Bacteroidetes and Firmicutes, were similar, the relative abundance of these dominant groups significantly differed, indicating that different types of vegetation might result in variations in the composition of soil bacterial community. In addition, functional genes of bacterial populations were similar among different types of vegetation, whereas its relative abundance was significantly differed. Most carbon fixation genes showed a high relative abundance in P. sylvestris, vs. recalcitrant carbon decomposition genes in A. halodendron, suggesting the variations in carbon cycling potential of different types of vegetation. Abundance of assimilatory nitrate reduction genes was the highest in P. sylvestris, vs. dissimilatory nitrate reduction and nitrate reductase genes in A. halodendron, indicating higher nitrogen gasification loss and lower nitrogen utilization gene functions in A. halodendron. The structures and functional genes of soil bacterial community showed marked sensitivities to different plant species, presenting the potentials for regulating soil carbon and nitrogen cycling.

submitted time 2020-10-20 From cooperative journals:《Journal of Arid Land》 Hits700Downloads403 Comment 0

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