Residents’ perspectives and responses to environmental degradation in the upper Dadu River, eastern Tibetan Plateau

Environmental degeneration in the Tibetan Plateau attracts worldwide attention, whereas case studies on how the residents understand and respond to environmental degeneration are scarce. Using a Participatory Rural Appraisal method, this paper investigates how the people in different regions in the upper Dadu River understand and respond to environmental degeneration, based on comparative field surveys in three villages, in which Danzamu village is chosen from villages in the valley region, Kerma village from mountainside region, Rico village from the mountain and plateau region. The results show that： （1） although awakened to environmental degeneration, the residents in different regions have different responses. As agricultural labors have been transferred to the secondary and tertiary industries, population pressure in Danzamu and Kerma villages is mitigated. Residents in Danzamu village actively respond to natural disasters and forest degradation, as their livelihoods never rely on forests and rangelands again. Whereas the residents in Kerma village negatively respond to natural disasters, forest and meadow degradation and the ruin of wildlife resources, as their livelihoods still rely on stockbreeding. Labors in Rico village are hard to transfer to the secondary and tertiary industries, so they have to raise more livestock to make a living. Active measures are just taken to avoid livestock loss, not to avoid forest and meadow degradation and the ruin of wildlife resources. So the most fragile region is the mountain and plateau region and mountainside region, not the valley region. （2） Livelihood strategy is the key factor affecting the residents to respond to population pressure and environmental degeneration. So the framework of sustainable livelihood strategy should be used to explain and intervene in issues of population pressure and environmental degradation in ecotones. （3） Transferring agricultural labors to the secondary and tertiary industries were favorable to improving people＇s livelihood. It is necessary to reduce the education fees to speed up the pace of labors transferring in the mountainside region. In the mountain and plateau region, preferable ways also include the development of towns, highways, education equipment and other establishments.

Attenuation relations for horizontal peak ground acceleration and response spectrum in northeastern Tibetan Plateau region

The seismic intensity attenuation relations in northeastern Tibetan Plateau region are established by a regression analysis on isoseismal data. Then the attenuation relations for horizontal peak ground acceleration and short-period response spectrum for western North America are derived based on the database of HUO Jun-rong and strong mo-tion data from recent earthquakes. The attenuation relations of long-period response spectrum for western North America are developed by analyzing the broadband digital seismic recordings of southern California. By integrat-ing the short-period and long-period attenuation relationships, the attenuation relations for horizontal acceleration response spectrum in the period range of 0.04~6 s for western North America are established. The attenuation equation that accounts for the magnitude saturation and near-field saturation of high frequency ground motion is used. Finally the attenuation relations for horizontal peak ground acceleration and response spectrum for the region of northeastern Tibetan Plateau are developed by using the transforming method.

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.

Relationship between acute high altitude response, cardiac function injury, and high altitude de-adaptation response after returning to lower altitude

The relationship between acute high altitude response (AHAR), cardiac function injury, and high altitude de-adaptation response (HADAR) was assessed. Cardiac function indicators were assessed for 96 men (18 - 35 years old) deployed into a high altitude (3700 - 4800 m) environment requiring intense physical activity. The subjects were divided into 3 groups based on AHAR at high altitude: severe AHAR (n = 24), mild to moderate AHAR (Group B, n = 47) and non-AHAR (Group C, 25);and based on HADAR: severe HADAR (Group E, n = 19), mild to moderate HADAR (Group F, n = 40) and non-HADAR (Group G, n = 37) after return to lower altitude (1,500 m). Cardiac function indicators were measured after 50 days at high altitude and at 12 h, 15 days, and 30 days after return to lower altitude. Controls were 50 healthy volunteers (Group D, n = 50) at 1500 m. Significant differences were observed in cardiac function indicators among groups A, B, C, and D. AHAR score was positively correlated with HADAR score (r = 0.863, P < 0.001). Significant differ- ences were also observed in cardiac function indicators among groups D, E, F, and G, 12 h and15 days after return to lower altitude. There were no significant differences in cardiac function indicators among the groups, 30 days after return to lower altitude, compared to group D. The results indicated that the severity of HADAR is associated with the severity of AHAR and cardiac injury, and prolonged recovery.

The response law of far-field seismic ground motion of the Wenchuan earthquake and its damaging mechanism in the Loess Plateau

A series of housing collapses and other serious damage was caused by the 2008 Wenchuan M_(S)8.0 earthquake in the seismic intensity Ⅵ areas of the Loess Plateau, which is hundreds of kilometers away from the epicenter, and which showed a remarkable seismic intensity anomaly. The seismic disasters are closely related to the seismic response characteristics of the site, therefore, the systematic study of the far-field seismic response law of the Wenchuan earthquake in the Loess Plateau is of great significance to prevent the far-field disaster of great earthquake. In this paper, the seismic acceleration records of several bedrock stations and loess stations from the seismogenic fault of the Wenchuan earthquake to the Loess Plateau were collected, and the attenuation law of ground motion along the propagation path and the characteristics of seismic response on the loess site are studied,and the mechanism of amplification effect of ground motion is analyzed based on the dynamic feature parameters of the loess site obtained through the HVSR method. Taking a typical loess site of thick deposit as the prototype, a series of shaking table tests of dynamic response of loess site models with different thicknesses were carried out.Amplification effect, spectral characteristics of acceleration in model sites were analyzed under the action of a farfield seismic wave of the Wenchuan earthquake. The results show that seismic attenuation on the propagation path along the NE strike of the seismogenic fault to the Loess Plateau is slower than that in other directions, and the predominant period range of ground motion on bedrock site of the Loess Plateau presents broadband characteristics. Because the natural periods of loess sites with thick deposits are within the predominant period range of bedrock input wave, loess sites appear significant amplification effect of ground motion, the horizontal acceleration of ground motion exceeds 0.1 g, the seismic intensity reaches 7°. The thicker the loess deposit is, the more significant the change of spectral characteristics of ground motion on loess sites, and the narrower the predominant period range of ground motion becomes, and the closer it is to the natural period of loess sites.Therefore, for some old houses on thick loess sites, the poor seismic performance and strong seismic response eventually led to their collapses and damages because their natural periods are very close to the predominant period of ground motion of the Wenchuan earthquake on thick loess sites;For these damaged high-rise buildings,the resonance effect might be the main reason for their damages because their natural periods are included in the predominant period range of ground motion of the Wenchuan earthquake on thick loess sites.These research results would provide a basis for seismic disasters prediction and evaluation and seismic design of construction engineering in the Loess Plateau.

Response of Photosynthetic Plankton Communities to Late-Holocene Climate Change on the Tibetan Plateau

Sediment records from Tibetan lakes record dramatic climatic variability of the Tibetan Plateau in NW China during the Holocene.Here we investigated ancient communities of photosynthetic microbial communities in

Interannual Changes of Land Surface Radiation Components in Loess Plateau and Their Responses to Climate Change

In this paper,land surface observation data at semi-arid climate and environmental observation station（ SACOL station） of Lanzhou University during 2006- 2012 and the data of Yuzhong meteorological station were used to analyze the responses of land surface radiation budget components to climate fluctuation,study the interannual variability of surface albedo,and discuss the feedback of various land surface process parameters on the interannual fluctuations of temperature and precipitation in Loess Plateau. According to the type of precipitation in Loess Plateau,the year was divided into winter and summer in order to get more significant interannual variability and correlation. The results showed that the trends of temperature and precipitation during 2006- 2012 were consistent with the warming and drying total trend in recent years in Loess Plateau. Shallow surface soil moisture and temperature showed a good response to temperature and precipitation,and the annual variation of summer half year had greater impact on the trend in the whole year. Incident solar radiation increase was major reason for climate warming in the Loess Plateau region.The combined effect of climatic factors was the reason for the change of surface albedo. Through the distinguish inquiry by winter and summer data,it was obtained that most correlations between summer radiation components and climatic factors have been improved,and partial correlations between winter radiation components and climatic factors have been increased.

Enhanced precipitation responses over the Tibetan Plateau following future Tambora-size volcanic eruption

Hydroclimate over the Tibetan Plateau(TP)notably influences the eco-environment of the Northern Hemisphere.Given its high elevation and complex topography,the climate in the TP shows a high sensitivity to anthropogenic warming and volcanic-induced cooling.The mechanism by which a future volcanic or similar radiative perturbation affects precipitation in the TP under an anthropogenic warming climate must be addressed not only to enable regional adaptation but deepen our understanding of how a climate system evolves under such a dual force.Here,based on the Community Earth System Model version 1.2 and ensemble simulations under pre-industrial and RCP8.5 scenarios,we showed that a Tambora-sized volcanic perturbation led to severe rainfall reduction over the south TP in the following summer(June-August).Evaporation response accounted for a minor and relatively constant share of precipitation reduction following the Clausius-Clapeyron scaling,whereas dynamic processes triggered an El Nino-like response in the eastern equatorial Pacific,which suppressed the Walker and Hadley circulation and contributed to drying anomalies.Global warming renders the post-Tambora hydroclimate responses with 30%higher severity as a result of the increased climatological moisture content and intensified El Nino response,which enhanced hydroclimate sensitivity and attenuated monsoon circulation.The results illustrate the amplification effect of global warming on the plateau's hydroclimate responses to external forcings,which may add another layer of uncertainty on climate adaptation in this already complex region.

Strengthening the three-dimensional comprehensive observation system of multi-layer interaction on the Tibetan Plateau to cope with the warming and wetting trend

Changes in the water cycle on the Tibetan Plateau(TP)have a significant impact on local agricultural production and livelihoods and its downstream regions.Against the background of widely reported warming and wetting,the hydrological cycle has accelerated and the likelihood of extreme weather events and natural disasters occurring(i.e.,snowstorms,floods,landslides,mudslides,and ice avalanches)has also intensified,especially in the highelevation mountainous regions.Thus,an accurate estimation of the intensity and variation of each component of the water cycle is an urgent scientific question for the assessment of plateau environmental changes.Following the transformation and movement of water between the atmosphere,biosphere and hydrosphere,the authors highlight the urgent need to strengthen the three-dimensional comprehensive observation system(including the eddy covariance system;planetary boundary layer tower;profile measurements of temperature,humidity,and wind by microwave radiometers,wind profiler,and radiosonde system;and cloud and precipitation radars)in the TP region and propose a practical implementation plan.The construction of such a three-dimensional observation system is expected to promote the study of environmental changes and natural hazards prevention.

Responses of Ecosystems to Ecological Compensation in a Key Ecological Function Area of the Loess Plateau

Evaluation of the ecological effects of eco-compensation policies helps analyze policy rationality and feasibility and provides scientific and practical bases for perfecting eco-compensation systems. Taking the key ecological function area of the Loess Plateau, China as a case study, we have evaluated ecosystem responses to the Grain-for-Green Project that commenced in 1999. Six indicators were selected to assess changes in ecosystem structure, quality and function. The results showed that implementation of the Grain-for-Green Project has reduced sloping cropland by 1571 km2 and increased ecological land by 1337 km2. The increase in ecological land alters ecosystem structures across the study area and the decline in sloping cropland reduces farming activity interference; both of these are conducive to the restoration of natural vegetation. From 2000 to 2010, the vegetation cover of grassland, desert and forest ecosystems increased 10.89%, 8.34% and 4.24% respectively and average NPP rose 51%, with an average annual growth rate of around 5%. This indicates that eco-compensation has promoted the improvement of ecosystem quality. Total biomass of ecosystems increased two times on average from 2000 to 2010, meaning that the carbon sequestration capacity of ecosystems also increased. The reduction in the area of water loss and soil erosion and the increase in retained runoff by forests indicate an improvement in ecosystem function and services on the Loess Plateau.

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。

黄土高原健康和衰退刺槐林径向生长对气候的响应

全球气候变化导致的区域森林生长衰退和死亡普遍发生,并对森林生态系统结构和组成以及主要生态系统服务功能产生重要影响,然而相关研究在国内还显偏少。根据黄土高原延安羊圈沟小流域人工刺槐林健康和衰退个体分别构建了刺槐健康和衰退树轮年表,并对人工刺槐林健康和衰退年表特征及对气候响应敏感性进行了对比分析。结果表明刺槐衰退年表质量较低,其年表统计参量,包括平均敏感度、样芯间相关系数、信噪比和样本群体代表系数均要低于刺槐健康年表。刺槐衰退年表在生活史早期(1985—2007年)与生长健康年表的波动趋势相类似,而在生活史晚期(2008—2016年)与健康年表指数出现生长分离现象,生长速率明显偏低。年表与气候要素响应分析表明刺槐生长衰退年表对气候要素响应敏感性要低于刺槐生长健康年表,但是两者均含有干旱胁迫气候信号,主要体现在与温度呈负相关关系,与降雨和干旱指数的正相关关系。年表与极端气候年份的时序叠加分析表明,生长健康和衰退年表对极端干旱年份响应敏感性均较高,表明极端干旱胁迫条件对刺槐生长健康和衰退个体均有抑制性影响;生长健康年表对极端湿润年份响应敏感性明显高于衰退年表,表明刺槐健康个体比衰退个体更能有效利用湿润年份有利条件,而具有较高的生长速率。研究揭示出黄土高原健康和衰退刺槐个体生长趋势变化及对气候响应敏感性均存在明显差异性,将为气候变化背景下人工刺槐林生长衰退和死亡预测模型建立提供科学依据,因而对黄土高原人工刺槐林生态恢复和保护及可持续经营具有科学价值。

基于HEC-HMS的黄土高塬沟壑区流域城市化对洪水情势的影响

黄土高塬沟壑区城市化过程中下垫面硬化会影响暴雨水文情势,增大洪水模拟预报难度。为实现对流域城市洪水灾害的预警,基于HEC-HMS水文模型,分别率定砚瓦川流域城市化前后不同时期土地利用条件下的产汇流参数,开展极端暴雨洪水情景设计,揭示流域城市化对不同重现期洪水的水文效应。结果表明:建立的HEC-HMS降雨-径流模型适用于黄土高塬沟壑区洪水预报,其模拟综合合格率为81.25%,平均Nash效率系数为0.82;流域城市化对重现期短的洪水要素变化影响较大,且洪量变化幅度大于洪峰变化幅度,100 a一遇洪水的洪峰和洪量的增幅分别为4.54%和6.40%,5 a一遇洪水的洪峰和洪量的增幅分别为7.06%和9.49%;各子流域设计洪水对流域城市化的响应分布具有空间差异性,以西北部地区响应为最强,其次为南部地区,东北部地区最弱。

坡向对六盘山人工华北落叶松林径向生长⁃气候关系的影响

黄土高原半干旱地区人工林生长受水分和温度影响显著,坡向作为重要的立地因子,在水热条件再分配中起到了决定性的作用。利用树木年轮学方法测定了1995—2020年六盘山叠叠沟小流域阴坡、半阴坡和阳坡的华北落叶松(Larix gmelinii var.principis⁃rupprechtii)人工林优势木逐年树轮宽度,建立树轮宽度标准年表(STD)和差值年表(RES)分析不同坡向林木生长特征及对气候响应的敏感性差异。研究结果表明:(1)各坡向优势木年表质量表现为阴坡最好、阳坡最差。(2)阴坡树木受最高气温和最低气温抑制作用显著(上年6、11月和当年7月);半阴坡树木与当年7月平均气温显著负相关;阳坡树木与平均气温的相关性低。(3)不同坡向树木均与上年8月降水量显著正相关,且阳坡树木对降水量的响应敏感性高于阴坡和半阴坡;半阴坡树木还受当年7月相对湿度的促进作用。(4)阳坡树木对干旱胁迫的响应敏感性高于半阴坡和阴坡,其中气象因素对阴坡树木径向生长变化的解释率最低。综上所述,六盘山半干旱区华北落叶松对气候响应的敏感性较高,且阳坡主要受降水量影响,阴坡受最高气温和最低气温影响较大,半阴坡则受温度和降水的共同调节。若发生干旱事件,阳坡树木径向生长下降幅度要远高于阴坡和半阴坡。结果为黄土高原土石山区华北落叶松人工林保护和可持续经营提供科学依据。

内嵌负泊松比型耦合蜂窝结构的共面冲击响应

为提升蜂窝结构共面的力学性能,引入了内凹负泊松比结构,并将其内嵌到传统六边形蜂窝共面孔隙内,复合成一种新型内嵌负泊松比型耦合蜂窝结构。利用显式动力学有限元方法研究了内嵌负泊松比型耦合蜂窝结构的共面在不同冲击速度作用下的冲击响应特性和能量吸收能力。结果表明:耦合蜂窝结构的变形模式受到冲击速度和耦合角的影响;耦合蜂窝结构冲击端和固定端的名义应力-名义应变曲线与其变形模式和耦合角有关,且耦合角越大,名义应力水平越低;耦合蜂窝结构的平台应力和比吸能均随着耦合角的增大而减小,在高速冲击时,其平台应力降低2%~9%,比吸能降低7%~20%;相对密度影响耦合蜂窝结构的平台应力和能量吸收能力。

GM管通用自动化测试软件平台设计

GM管是常用气体类前端辐射探测器之一,其性能指标决定了应用场景、电路设计与适用设备等。为探究新研GM管是否满足预期设计指标与生产工艺要求,需要经过充分的试验验证。针对GM管关键性能指标,设计一款测试软件平台,适用于不同型号GM管,满足批量化GM管坪特性、探测效率、灵敏度、能量响应等关键性能指标的自动化测试,减少人工干预,为新型GM管的工艺探索、研制定型与大批量GM性能验证、生产检测奠定了软件平台基础。

气候变暖背景下黄河中游晋西黄土高原的植被响应

笔者介绍了黄河中游晋西黄土高原概况,综述了植被分布、植被覆盖、植被物种多样性及植被物候对气候因子的响应。黄河中游晋西黄土高原属于半干旱地带,植被主要为草本、灌木及一些适宜半干旱条件的乔木,水热条件是影响黄河中游晋西黄土高原植被覆盖的主要限制因子。黄河中游晋西黄土高原山地植物物种多样性分布的主要特征是乔木物种多样性、草本物种多样性和系统发育多样性均随海拔升高而递减,灌木物种多样性无明显变化趋势;乔木物种丰富度与生长季节平均温度呈显著正相关。2000年至2015年,黄河中游晋西黄土高原植被物候发生显著变化,植被生长季开始日期提前和结束日期推迟的区域较多。

高原急性缺氧肠道应激损伤小鼠模型的构建与评价

目的通过模拟急性缺氧环境,建立实验性高原小鼠肠道应激损伤模型,为探讨高原急性胃肠病的致病机制以及防治措施奠定基础。方法根据体重按随机数字表法,将36只SPF级成年雄性BALB/c小鼠分为常氧24 h组、常氧72 h组、低氧24 h组和低氧72 h组,每组9只。常氧对照组小鼠饲养于常规屏障环境中,低氧应激组饲养于屏障环境中的低氧舱内,氧气浓度设定为10%以模拟高原环境,分别应激24 h和72 h,建立急性缺氧所致肠道损伤模型。造模结束后,称量小鼠体重,用1%戊巴比妥钠麻醉后断颈处死各组小鼠,采集十二指肠和结肠组织并进行HE染色后观察肠道组织病理形态,通过蛋白质印迹和免疫组织化学法检测肠道组织中紧密连接相关蛋白表达水平,应用实时荧光定量PCR检测炎性细胞因子和趋化因子的mRNA表达水平,采用TUNEL染色法检测肠上皮细胞凋亡活性等指标,从而对该模型的肠道损伤相关表型进行评价。结果与常氧组相比,低氧24 h组和低氧72 h组的小鼠表现为体重减轻,十二指肠绒毛长度变短、隐窝结构异常、绒毛/隐窝比下降,结肠黏膜炎性细胞浸润、隐窝结构不规则。低氧24 h组和低氧72 h组小鼠的十二指肠和结肠组织中闭锁蛋白(Occludin)及闭锁小带蛋白(zonula occludens-1,ZO-1)表达水平明显下降(P<0.05),十二指肠组织中促凋亡蛋白Bax表达明显上调,抑凋亡蛋白Bcl-2表达明显下调(P<0.05),而且肠上皮细胞的凋亡活性显著增强(P<0.05)。此外,缺氧应激24 h和72 h后,小鼠十二指肠组织中白细胞介素(interlenkin,IL)-1β、IL-6、单核细胞趋化蛋白-1(monocyte chemoattractant protein-1,MCP-1)及肿瘤坏死因子-α(tumour necrosis factor-α,TNF-α)mRNA水平显著增高(P<0.05),缺氧应激24 h后,小鼠结肠组织中炎性细胞因子的表达水平无显著变化(P>0.05),但缺氧应激72 h后,小鼠结肠组织中促炎因子IL-1β、TNF-α、IL-6、MCP-1以及抗炎因子IL-10 mRNA水平显著增高(P<0.05)。结论利用低氧舱模拟高原急性缺氧环境可导致应激小鼠肠道组织结构异常、肠屏障功能障碍,并诱导肠上皮细胞凋亡,引发肠道炎性反应。这些结果表明急性缺氧应激肠道损伤小鼠模型构建成功。

青海高原生长归一化差值植被指数对气候暖湿化响应的年代际变化

本文利用1982~2018年美国国家海洋和大气局(NOAA)先进甚高分辨率辐射计(AVHRR)观测得到的归一化差值植被指数(NDVI)数据集和中国区域高分辨率近地面气温和地面降水率驱动数据集(CMFD),采用线性倾向估计、M–K检验、偏相关和方差分析等方法,研究了气候暖湿化背景下青海高原生长季(5~9月)地表植被变化特征及其对气候暖湿化响应的年代际变化。结果表明:(1)1982~2018年,青海高原生长季地表植被呈由东南向西北逐渐减小的空间分布特征,整体呈显著增加趋势(p<0.01),气候倾向率达0.01(10 a)-1,但在空间上呈两极化发展,在青海高原东部和西南部植被显著变好(面积占57.3%)的同时,青海高原西北部的柴达木盆地地表植被表现为退化态势(面积占14.8%)。(2)1982~2018年青海高原气候整体呈暖湿化特征,但在1990年代中后期发生了显著的趋势变化,不同时段气候暖湿化的区域和强度存在差异,P1时段(1982~1998年)的增温强于P2(1998~2018年)时段,而P2时段的变湿强于P1时段;青海高原生长季地表植被在1998年之前为波动上升,趋势不显著,但从1998年开始出现显著增加趋势(p<0.05),这与青海高原地面降水率的变化相一致。(3)在青海高原气候暖湿化不同阶段,地表植被对气候变化具有不同的响应,在P1时段,水分条件相对不足的情况下,地表植被对热量因子(气温)以负反馈为主,增温不利于地表植被的生长,特别是在黄河源区北部和青海湖附近;而在P2时段,在水分条件相对充足的条件下,地表植被对水分和热量因子均以正反馈为主,在二者的共同作用下,青海高原生长季地表植被出现了大范围好转。

北京市昌平区马池口村地源热泵系统设计与热平衡分析

通过使用模拟软件对北京市昌平区马池口村项目的供热制冷设计负荷和全年逐时动态负荷进行计算,结合项目的能源条件与建筑的负荷特点,设计了以地埋管地源热泵系统为主,空气源热泵与复合式太阳能热水系统作为辅助热源的复合式能源系统。通过TRNSYS软件模拟,分析了地埋管地源热泵系统承担75%供暖负荷时存在的土壤热平衡问题,验证了使用复合式太阳能热水系统为地埋管系统补热后地下岩土温度可维持在一定范围内,基本保持冷热平衡,确保系统安全稳定、高效运行。通过对系统节能效益分析,检验该复合式能源系统的节能降碳效果,为寒冷地区同类型项目提供参考。