Cosmogenic ^(26)Al/^(10)Be Burial Dating of the Uplift Rate of Southern Qinling Mountains since the Middle Pleistocene

Objective The Qinling Mountains （QM） in Central China is a natural harrier that corresponds to the boundary between the southern and northern climate and environment （Gong Hujun et al., 2017）. Northern QM is relatively steep, and southern QM is in contrast relatively low and gentle. Investigations have shown that the average uplift rate of northern QM since 17.8 Ma is approximately 0.19 mm/a （Yin Gongming et al., 2001）, whereas that of central QM since 0.36 Ma is approximately 0.32 mm/a （Wang Fei et al., 2004）. To date, however, few investigations have yet been conducted on the uplift rate of southern QM. Accordingly, we aim to obtain the uplift rate of southern QM by using the cosmogenic ^26A1/^10 Be burial dating method to determine the age of the highest river terrace on the southern slope of QM.

Effects of elevated CO_2 on net photosynthetic rate of trees in Changbai Mountain

Net photosynthetic rates (NPRs) of four species seedlings, Pinus koraiensis, Ptrius Syvestriformis,Fraxinus mandshuthe and Phellodendron amurense, were measured at different CO2 concentrations and time respectively in Changbai Mountain during the growing season in 1999. The seedlings were cultivated in open-top chambers (OTCs), located outdoors and exposed to natural sunlight. The experimental objects were divided into four groups by tree species. CO2 concentrations in chambers were kept at 500 μL-L-1 and 700 μL-L-1 and contrast chamber and contrast field were set. The results showed that the effects of elevated CO2 on NPR of the trees strongly depended on tree species and time. NPRs of Pin us koreaipsis and Pinus syvestriformis seedfings increased with the rising of CO2 concentration, while that of Phellodron amurense and haus mandshurica increased at some time and decreased at another time.

Slip Rate of Yema River–Daxue Mountain Fault since the Late Pleistocene and Its Implications on the Deformation of the Northeastern Margin of the Tibetan Plateau

The slip rate of Yema River-Daxue Mountain fault in the western segment of Qilian Mountains was determined by the dated offset of river risers or gullies. Results indicate that the left-lateral fault slip rate is 2.82± 0.20 mm/a at Dazangdele site, 2.00 ± 0.24 mm/a at Shibandun site, and 0.50± 0.36 and 2.80±0.33 mm/a at two sites in Zhazihu. The ideal average slip rate of the whole fault is 2.81 ± 0.32 mm/a. The lower slip rate confirms part of the displacement of Altyn Tagh fault was transformed into an uplifting of the strap mountains in the western segment of Qilian Mountains, whereas another part transformed into sinistral displacement of Haiyuan fault. This study illustrates that the slip of large strike-slip faults in the northeastern margin of the plateau transforms into crust thickening at the tip of the fault without large-scale propagation to the outer parts of the plateau.

A specific objective supplemental factor in evaluating acute mountain sickness: ΔHR in combination with SaO_2

Background: So far, there have been no measurements confirmed useful in diagnosing acute mountain sickness(AMS). The aim of this study was to determine the role of heart rate(HR) difference(ΔHR) and oxygen saturation(Sa O2) as objective risk factors in aiding the diagnosis of AMS.Methods: A total of 1,019 participants were assigned to either the acute exposure group(AEG): from 500 m to 3,700 m by flight within 2.5 hours(n=752); or the pre-acclimatization group(PAG): ascended to 4,400 m from 3,650 m within three hours by car after adapting 33 days at 3,650m(n=267). The questionnaires or measurements of resting Sa O2 and HR were completed between 18 and 24 hours before departure and after arrival.Results: Incidence of AMS was 61.3%(461) in AEG, with 46.1%(347) mild cases and 15.2%(114) severe cases. In PAG, the incidence was 38.9%(104), with 30.7%(82) mild cases and 8.2%(22) severe cases. The AMS subjects showed a significant increase in HR and a decrease in Sa O2 levels compared with the non-AMS subjects in both groups. ΔHR and post-exposure Sa O2 were significantly correlated with the Lake Louise Score(LLS) in both groups. Stepwise logistic regression analysis revealed the ΔHR >25 and Sa O2 <88% in AEG as well as ΔHR >15 and Sa O2 <86% in PAG to be independent risk factors of AMS. Combining these two measurements could specifically indicate participants with AMS, which showed a positive predictive value of 89% and specificity of 97% in AEG as well as 85% and 98% in PAG.Conclusion:ΔHR or Sa O2, as objective measurements, correlate with AMS. Combination of these two measurements may be useful as an additional specific and objective factor to further confirm the diagnosis of AMS.

Diurnal and seasonal variation of the elevation gradient of air temperature in the northern flank of the western Qinling Mountain range,China

The typically sparse or lacking distribution of meteorological stations in mountainous areas inadequately resolves temperature elevation variability. This study presented the diurnal and seasonal variations of the elevation gradient of air temperature in the northern flank of the western Qinling Mountain range,which has not been thoroughly evaluated. The measurements were conducted at 9 different elevations between 1710 and 2500 m from August 2014 to August 2015 with HOBO Data loggers. The results showed that the annual temperature lapse rates(TLRs) for Tmean,Tmin and Tmax were 0.45?C/100 m,0.44?C/100 m and 0.40?C/100 m,respectively,which are substantially smaller than the often used value of 0.60°C/100 m to 0.65°C/100 m. The TLRs showed no obvious seasonal variations,except for the maximum temperature lapse rate,which was steeper in winter and shallower in spring. Additionally,the TLRs showed significant diurnal variations,with the steepest TLR in forenoon and the shallowest in early morning or late-afternoon,and the TLRs changed more severely during the daytime than night time. The accumulated temperature above 0°C,5°C and 10°C(AT0,AT5 and AT10) decreased at a lapse rate of 112.8?C days/100 m,104.5?C days/100 m and 137.0?C days/100 m,respectively. The monthly and annual mean diurnal range of temperatures(MDRT and ADRT) demonstrated unimodal curves along the elevation gradients,while the annual range of temperature(ART) showed no significant elevation differences. Our results strongly suggest that the extrapolated regional TLR may not be a good representative for an individual mountainside,in particular,where there are only sparse meteorological stations at high elevations.

Changes in oxygen saturation can not help diagnose acute mountain sickness(AMS)： ascending to Lhasa on the Qinghai-Tibet train

Objective: Acute mountain sickness(AMS) is a common condition in individuals who ascend to altitudes over 2 500 m. There is no measurements that can reliably predict or diagnose this condition. We therefore determined whether pulse oximetry data are associated with the development of AMS and can help diagnose AMS. Methods: We studied 58 young male undergraduates who traveled from Chongqing(300 m) to Lhasa(3 658 m) by train. We collected data on the ascent profiles and AMS symptoms based on the Lake Louise Score(LLS). The resting arterial oxygen saturation(R-Sp O2) and pulse rate were then measured using finger pulse oximetry. Results: In Golmud(2 800 m) and Tanggula(5 200 m), R-SpO_2 was significantly lower in the AMS group than in the group without AMS(P<0.05). However, upon arrival in Lhasa(3 658 m), the R-SpO_2 was higher in the AMS group than in the non-AMS group(P<0.05). In Tanggula, the change in the SpO_2(CR-SpO_2) in the AMS group was higher than that in the non-AMS group(P<0.05). But in Lhasa, the CR-SpO_2 in the AMS group was lower than that in the non-AMS group(P<0.05). We also monitored heart rate(HR) throughout the study. In Xining(2 200 m) and Golmud, the HRs in the AMS group were higher than those in the non-AMS group. However, the HRs in the AMS group were lower than those in the non-AMS group in Tanggula and Lhasa. Conclusion: Based on the results of this study, the R-SpO_2 graph was not consistent. We can thus conclude that the utility of SpO_2 remains limited in the diagnosis of AMS. The results suggest that using pulse oximetry to diagnose AMS is not valuable in people ascending to Lhasa on the Qinghai-Tibet train.

Tectonic Evolution of the Middle Frontal Area of the Longmen Mountain Thrust Belt,Western Sichuan Basin,China

By analyzing the balanced cross sections and subsidence history of the Longmen Mountain thrust belt, China, we concluded that it had experienced five tectonic stages： （1） the formation stage （T3x） of the miniature of Longmen Mountain, early Indosinian movement, and Anxian tectonic movement created the Longmen Mountain; （2） the stable tectonic stage （J1） where weaker tectonic movement resulted in the Longmen Mountain thrust belt being slightly uplifted and slightly subsiding the foreland basin; （3） the intense tectonic stage （J2-3）, namely the early Yanshan movement; （4） continuous tectonic movement （K-E）, namely the late Yanshan movement and early Himalayan movement; and （5） the formation of Longmen Mountain （N-Q）, namely the late Himalayan movement. During those tectonic deformation stages, the Anxian movement and Himalayan movement played important roles in the Longmen Mountain＇s formation. The Himalayan movement affected Longmen Mountain the most; the strata thrust intensively and were eroded severely. There are some klippes in the middle part of the Longmen Mountain thrust belt because a few nappes were pushed southeastward in later tectonic deformation.

基于GNSS的西秦岭北缘断裂带现今活动特征研究

基于1999~2007年、2009~2013年、2013~2017年和2017~2021年共4期GNSS地壳运动速度场构建GNSS速度剖面,分析西秦岭北缘断裂带各次级断裂现今地壳差异运动特征,并进一步建立负位错模型反演获取各次级断裂现今闭锁程度与滑动亏损速率。结果表明:1)西秦岭北缘断裂带现今整体呈现出以左旋走滑为主、兼逆冲挤压的活动特征。2)1999~2007年,锅麻滩段和天水-宝鸡段整体处于强闭锁状态,漳县段和鸳凤段仅部分区段闭锁且闭锁程度较低,闭锁深度也较浅;2009~2013年,西秦岭北缘断裂带中段闭锁程度有所减弱,鸳凤段东部与天水-宝鸡段东部由较强闭锁转变为蠕滑状态,锅麻滩段和天水-宝鸡段中西部依然呈强闭锁状态;2013~2017年,西秦岭北缘断裂带整体处于较强闭锁状态,仅天水-宝鸡段东部呈蠕滑状态;2017~2021年,锅麻滩段中西部、漳县段、鸳凤段东部和天水-宝鸡段中部处于较强闭锁状态,鸳凤段中西部与天水-宝鸡段西部则呈蠕滑状态。3)各次级断裂滑动亏损速率整体分布特征与断裂闭锁程度基本一致。西秦岭北缘断裂带锅麻滩段和天水-宝鸡段中部现今处于较强闭锁状态,具有较强的应变能累积背景。

粤北山区2013—2022年短时强降水的统计特征

针对地形复杂的粤北山区,基于2013—2022年412个地面气象观测站逐小时降水数据,总结粤北山区短时强降水时空分布特征。结果表明:(1)粤北山区短时强降水频次有明显的年际变化,平均强度没有明显年际差异。(2)粤北山区短时强降水5月最多,6月次之,8月更次之;南海季风爆发时间和强度对粤北山区短时强降水频次及雨强甚至极端雨强都没有明显指示意义。(3)粤北山区短时强降水日变化呈双峰型,17:00前后为主高峰、06:00前后为次高峰;从冬到秋季,主高峰由凌晨过渡到傍晚。(4)短时强降水的空间分布大体呈现西南多东北少,易发区主要集中在清远英德到河源龙门一带。4到6月以佛冈为中心显著增多;7到9月短时强降水多发生于山谷地区。

供钾水平对宁南山区花椰菜产量及钾素平衡的影响

【目的】为宁夏冷凉花椰菜生产中钾肥合理施用提供科学依据。【方法】以宁夏冷凉主导花椰菜为试验材料,设置0(K_(0))、10(K_(10))、20(K_(20))、30(K_(30))、40 kg/667m^(2)(K_(40))5个施钾水平,通过田间试验,研究供钾对露地花椰菜产量、钾素吸收分配利用及土壤根层钾素质量与平衡的影响。【结果】供钾显著增加花椰菜产量,增产率在5.32%~16.24%,供钾水平与花球产量呈极显著的二次抛物曲线关系,最高产量为3 529.43 kg/667 m^(2),最佳供钾水平为24.28 kg/667 m^(2)。在苗期和莲座期茎叶是花椰菜钾元素的累积中心,不同处理茎叶分配比例在49.67%~90.49%,进入成熟期花球是花椰菜钾元素的累积中心,不同处理花球累积分配比例在42.25%~53.73%,整株花椰菜钾素累积量苗期以K_(30)处理最高,莲座期和成熟期均以K_(20)处理最高,较对照分别显著提高69.40%、79.38%。钾肥利用效率为21.77%~40.31%,以K20处理的钾肥利用率、贡献率及农学效率均最高,分别为45.28%,21.31%、38.670 kg/kg。供钾水平低于20 kg/667 m^(2)时,土壤钾素平衡表现为亏缺,供钾水平超过30 kg/667 m^(2)钾素盈余由负转正,再继续投入钾肥,钾素盈余。【结论】综合考虑花椰菜钾素吸收利用分配与产量和土壤钾素有效性与菜田钾素收支平衡等因素,建议宁夏南部山区花椰菜适宜的供钾水平为21.82~29.24 kg/667 m^(2)。

构造活动与地表作用耦合下的河流演化过程及动力学机制——以青海湖和倒淌河为例

新生代以来,青海湖在河流侵蚀与构造活动耦合下由外流湖泊转化为内流湖泊,但其动力学成因一直悬而未决。倒淌河作为青海湖由外流转换为内流的关键通道,其动力学演化历史记录着这一重要的构造与地貌转变地质事件。基于最新开发的地貌演化有限体积法数值计算程序,模拟山脉隆升与河流下切共同作用下的河流倒淌形成与演化过程,定量分析隆升速率和河流下切系数对不同的流域演化模式的影响,探讨倒淌河演化的动力学机制,为认识倒淌河流域形成过程与青海湖形成成因提供支撑。结果表明,倒淌河流域的水系重组和倒淌河流向的转变主要受到由日月山断层活化引起的山脉快速隆升与河流下切影响;日月山隆升速率是影响倒淌河流域能否发生水系重组的控制因素;当河流被隆升的山脉阻挡而倒淌时,河流下切系数是控制流域重组速率的因素。

北方土石山区坡面水土流失特征研究

[目的]揭示北方土石山区坡面水土流失规律,为山区土壤侵蚀防治和生态建设提供科学依据。[方法]利用1988—1991年坡面径流小区观测数据,运用统计和相关分析等方法,对不同下垫面条件下坡面水土流失特征进行了分析,并探讨了坡面径流深度、土壤侵蚀模数、土壤入渗率与有效降雨量、平均降雨强度、降雨历时、降雨等级的关系。[结果](1)在5°08′~24°08′坡度范围内,坡面径流深度随坡度增加逐渐减小,土壤侵蚀模数和土壤入渗率随坡度增加逐渐增大;(2)在2.18~33.19 m坡长范围内,坡面径流深度随坡长增加逐渐减小,土壤侵蚀模数和土壤入渗率随坡长增加呈现先增后减的变化趋势,存在临界坡长;(3)随着植被覆盖度增加,坡面径流深度、土壤侵蚀模数迅速减小,土壤入渗率逐渐增加;裸地的坡面径流深度和土壤侵蚀模数显著高于30%植被覆盖度坡面,但植被覆盖度由30%增加到60%,90%时,坡面水土流失过程的影响差异并不明显,说明在水土流失治理中存在临界植被覆盖度;(4)坡面径流深度、土壤侵蚀模数主要受到有效降雨量和平均降雨强度影响,且均呈显著正相关;而土壤入渗率主要受到平均降雨强度和降雨历时影响,与平均降雨强度呈显著正相关,与降雨历时呈显著负相关;随降雨等级的增加,坡面径流深度和土壤侵蚀模数呈增加趋势而土壤入渗率呈先增加后减少的趋势。[结论]下垫面条件和降雨因素对北方土石山区坡面水土流失过程产生了重要影响。未来应结合室内试验和模型模拟,进一步加强该区域不同自然因素和人类活动对坡面水土流失过程和影响机制的研究。

汶川M_(s)8.0地震隧道易损性及平均损失率分析

基于汶川地震震害资料,通过回归分析得到了山区隧道结构整体与各部分的地震易损性模型。选择峰值地面加速度(peak ground acceleration,PGA)作为地震动参数,以对数正态分布函数作为易损性模型,利用极大似然估计得到隧道结构整体及各部分(洞口浅埋段、洞口过渡段、普通段、断层破碎段)的地震易损性曲线,对比分析了隧道整体及各部分的地震易损性特点并进行了探讨。结果表明:轻微破坏条件下,洞口浅埋段的地震易损性要高于其他部分。随着破坏程度的增加,断层破碎带段的地震易损性逐渐高于隧道其他部分。根据隧道结构特定破坏等级的损失比,建立了隧道的平均损失率模型。依据文中建立的隧道易损性模型及平均损失率模型可以在将来发生类似地震时快速地进行地震损失评估。

重庆山区4种鲟仔、稚、幼鱼生长特性对比研究

为有效筛选出适宜重庆山区养殖的鲟鱼品种,将卵黄囊消失的施氏鲟、西杂鲟(西伯利亚鲟♀×施氏鲟♂)、施杂鲟(施氏鲟♀×西伯利亚鲟♂)、大杂交鲟(达氏鳇♀×施氏鲟♂)仔鱼饲养在直径2 m、高0.6 m的蓝色圆形玻璃钢盆中,每盆3000尾,开始时投喂打碎的水蚯蚓,7 d后(全长约3 cm),用微粒饲料与水蚯蚓浆制成软颗粒饲料,阴干后投喂,经15~20 d转食后,投喂鲟鱼专用微粒饲料,养殖84 d后比较分析4种鲟鱼胚后发育时间,形态特征,及仔、稚、幼鱼成活率、生长特性等。试验结果显示:在水温(17.94±0.54)℃、溶解氧质量浓度(8.91±0.32)mg/L、pH(8.09±0.43)的条件下,大杂交鲟、西杂鲟胚后发育时间早于施杂鲟和施氏鲟;4种鲟幼鱼外部形态特征均有区别;西杂鲟成活率最高,为(65.33±2.12)%,显著高于施氏鲟、施杂鲟和大杂交鲟;7日龄后,4种鲟鱼特定生长率随着日龄增加而降低;从生长模型可知,西杂鲟全长生长速度最快,从(0.81±0.34)cm增长至(16.67±1.37)cm,大杂交鲟体质量生长速度较快,西杂鲟次之,但77日龄后西杂鲟体质量生长速度超过大杂交鲟。试验结果表明,西杂鲟在重庆山区山泉水养殖条件下具有明显的生长优势。

兴隆山典型林分土壤呼吸的空间异质性分析

为探明兴隆山森林生态系统典型林分土壤碳呼吸的日变化、月际动态特征及其影响因子,利用LI-8100土壤呼吸测定室对辽东栎林、山杨-白桦混交林、油松林和青杄林土壤呼吸速率(R_(s))进行连续观测,采用指数方程拟合R_(s)对土壤温度(T_(5))、土壤含水量(W_(5))的响应.结果表明,各林分覆枯落物与裸地的Rs日变化均呈先增加后下降的单峰型曲线,但达到峰值的时间各不相同,各林分R_(s)与T_(5)间均有显著相关性.各林分R_(s)在8月达到峰值,为2.6~7.0μmol/(m^(2)·s),与其土壤性质的表现一致:辽东栎林和杨桦混交林土壤容重较低,具有较高的全氮、全磷及有机质含量,其Rs亦较高,油松林、青杄林表现相反.枯落物对各林分R_(s)的贡献率分别为59.83%(辽东栎林)、41.46%(山杨-白桦混交林)、28.68%(油松林)和11.83%(青杄林),各林分覆枯落物时的Rs明显高于裸地.不同林分Rs的变化特征是水热因子联合效应的结果,R_(s)受T_(5)影响最大,受W_(5)的影响作用相对较小.

陕北安塞山地苹果树干液流变化特征及其对环境因子的响应

为揭示陕北黄土区不同生育期山地苹果树蒸腾耗水规律及其对环境因子的响应,为陕北黄土区农业水资源的高效利用及山地苹果产业的可持续发展提供科学依据。采用热扩散式探针法(TDP)和自动气象站对陕北黄土区山地苹果树干液流速率和环境因子进行连续动态监测,分析山地苹果液流速率的变化规律及其与太阳辐射、气温和大气相对湿度等环境因子的关系。结果表明:不同生育期山地苹果树干液流速率日变化总体上呈“几”字型曲线,具有明显的昼夜变化规律,有微弱的夜间液流产生;不同生育期山地苹果树干液流日累积量表现为果实膨大期(14.396 kg·d^(-1))>幼果期(14.10 kg·d^(-1))>果实成熟期(9.682 kg·d^(-1))>开花期(6.49 kg·d^(-1))>着色期(4.104 kg·d^(-1));晴天山地苹果树干液流速率高于多云和阴雨天气;构建了山地苹果树干液流速率与环境因子的多元回归模型,各方程均达到了极显著水平,各生育期方程决定系数R2均大于0.81,拟合良好。陕北黄土区夏季果实膨大期蒸腾耗水量最大,应及时于日落前或日出后进行补水灌溉。

宁南山区农膜机械化回收现状分析与建议——以原州区为例

农用塑料膜对农业增产增收发挥了重要作用,然而随着农膜的大量使用,白色污染也越发严重。本文总结了宁夏南部山区原州区农膜的使用和回收利用现状,首先归纳了原州区近年农用塑料膜的使用情况,随后从政策制订和生产实践角度阐述了当地废弃农膜机械化回收利用的现状、主要做法和存在的问题。针对这些问题提出了相关对策建议,包括推广先进的回收技术和设备、加强政策引导以及使用厚度≥0.015mm的农膜等,以期进一步提高农业残膜的回收率和效率,减少环境污染,为山区农膜机械化回收提供参考。

马雅雪山断裂金强河段晚第四纪断错地貌及滑动速率确定

祁连山东段发育了多条大型活动断裂,如近东西向展布的天桥沟-黄羊川断裂及北西西向展布的金强河断裂、毛毛山断裂、老虎山断裂等,在马雅雪山北麓、宝泉山隆起北缘还发育了一条整体呈北西-北西西向展布的马雅雪山断裂。其中,前人已对天桥沟-黄羊川断裂、金强河断裂、毛毛山断裂、老虎山断裂的晚第四纪活动开展了大量的研究,相比而言,马雅雪山断裂的研究程度还较低,其最新构造活动特征及其与区域主干活动断裂之间的关系等尚不清楚。马雅雪山断裂构成了天祝盆地与南部山体、丘陵的分界线,迹线清晰,断层三角面、断层槽谷多见,局部冲洪积阶地可见线性展布的断层陡坎,显示出断裂在晚第四纪有一定的活动。本研究对马雅雪山断裂西部的金强河段开展了实地调查,重点对马营沟及小黑刺沟2处的阶地断层陡坎开展了高精度地形地貌测量及阶地地貌面定年,对滑动速率进行了厘定。研究结果表明,马雅雪山断裂金强河段晚第四纪活动显著,断裂最近强震活动发生在8.21~3.43 ka BP,晚更新世晚期以来的垂直滑动速率为0.45~0.63 mm/a。

山区高速公路复杂路段改扩建方案研究

以太旧高速公路桑掌至坡头段为研究对象,结合既有道路指标、构造物的分布及使用情况、周边采空区影响、河道防洪、村庄及文物分布等,统筹考虑行车安全性和旧路利用率等因素布设多个改扩建方案进行综合对比论证,合理确定改扩建方案,对山区高速公路复杂路段改扩建方案的选择具有一定指导意义。