The sources and seasonal fluxes of particulate organic carbon in the Yellow River     

Yuanxin Qu  Zhangdong Jin  Jin Wang  Yunqiang Wang  Jun Xiao  Long-Fei Gou  Fei Zhang  Chun-Yao Liu  Yongli Gao  Marina B. Suarez  Xiaomei Xu 《地球表面变化过程与地形》2020,45(9):2004-2019

The Yellow River transports a large amount of sediment and particulate organic carbon (POC), which is thought to mainly derive from erosion of the Chinese Loess Plateau (CLP). However, the compositions, sources and erosional fluxes of POC in the Yellow River remain poorly constrained. Here we combined measurements of mineralogy, total organic carbon content (OC_total), stable organic carbon isotopes (δ¹³C_org), radiocarbon (¹⁴C) activity of organic matter in bulk suspended sediments collected seasonally from the upper and middle Yellow River, to quantify the compositions and fluxes of the POC and to assess its sources (biospheric and petrogenic POC, i.e. POC_bio and POC_petro, respectively). The results showed that the POC loading of sediments was controlled by mineralogy, grain size and specific surface area of loess particles. The F_mod of POC (0.71 to 0.31) can be explained by mixing of POC_petro with modern and aged POC_bio. A binary mixing model based on the hyperbolic relationship of the F_mod and OC_total revealed a wide range of ages of POC_bio from 1300 to 11100 ¹⁴C years. Relative to the upstream station, the annual POC_bio and POC_petro fluxes in the Yellow River are more than doubled after it flows crossing the CLP within 35% drainage area gain, resulting in POC_bio and POC_petro yields of the CLP at 3.50 ± 0.59 and 0.48 ± 0.49 tC/km²/yr, respectively. POC flux seasonal variation revealed that monsoon rainfall exerts a first-order control on the export of both POC_bio and POC_petro from the CLP to the Yellow River, resulting in more than 90% of the annual POC exported during the monsoon season. Around one third of annual POC erosional flux was transported during a storm event period, highlighting the important role of extreme events in POC export in this large river. © 2020 John Wiley & Sons, Ltd.  相似文献   

软弱破碎围岩双连拱隧道安全施工与监测   总被引：8，自引：2，他引：6  

赖金星  谢永利  李华  赵严峰 《工程地质学报》2006,14(4):513-517

针对软弱破碎Ⅱ类围岩双连拱隧道采用三导洞施工方法的特点,阐述了其安全施工技术要点,实际施工中,就其监测内容及监测结果进行了实时分析,为隧道安全施工提供了依据,长期监控量测结果表明,该隧道结构是安全的,达到了围岩与支护结构体系安全与稳定的要求,所采用的安全施工措施以及信息化施工方法对类似工程具有指导和借鉴意义.  相似文献   

Seasonal cycle of topography in the Bohai Sea and Yellow Sea and its relationships with atmospheric forcing and oceanic adjustment based on altimetry data   总被引：1，自引：0，他引：1  

王凡林鹏飞  陈永利唐晓晖 《中国海洋湖沼学报》2004,22(3):256-264

Seasonal cycle is the most significant signals of topography and circulation in the Bohai Sea (BS)and Yellow Sea (YS) forced by prevailing monsoon and is still poorly understood due to lack of data in their interiors. In the present study, seasonal cycles of topography in the BS and YS and its relationship with atmospheric forcing and oceanic adjustment were examined and discussed using TOPEX/Poseidon and ERS-I/2 Sea Level Anomalies (SLA) data. Analyses revealed complicated seasonal cycles of topography composed mainly of 2 REOF modes, the winter-summer mode (WlM) and spring-autumn mode (SAM). The WlM with action center in the BS displayed peak and southward pressure gradient in July, and valley and northward pressure gradient in January, which is obviously the direct response to monsoon with about l-month response time. The SAM with action center in the western south YS displayed peak and northward pressure gradient in October and valley and southward pressure gradient in April. After the mature period of monsoon, the action center in the BS becam eweakened while that in the western south YS became strengthened because of regional convergence or divergence induced by seasonal variations of the Taiwan Warm Current and Yellow Sea Coastal Current. The direct response of topography to monsoon resulted in the WIM, while oceanic adjustment of topography played an important role in the forming of the SAM.  相似文献   

CT自动注射器在小儿增强扫描中应用   总被引：1，自引：0，他引：1  

张英  陈燕萍 《CT理论与应用研究》1998,7(3):33-34

本文总结了ＣＴ自动压力注射器在小儿增强扫描中的应用,根据小儿各脏器功能,发育不完善,对造影剂反应不能表达或表达不确切,对扫描不能配合等难点,总结了应用方法,对自动注射器安全应用于小儿提供了切实可行的经验。  相似文献   

基于GPRS网络的RTK技术在高程检查中的应用     

陈永立 《测绘标准化》2009,(2):31-33

简要叙述了基于GPRS网络的RTK技术的原理及其特点,通过实例说明了在利用RTK技术进行实时定位时平面坐标转换和高程拟合的方法,并对利用基于GPRS网络的RTK系统进行1∶10000比例尺地形图高程测量的精度作了分析。结果表明,基于GPRS网络的RTK系统完全满足1∶10000地形图高程检查的需要。  相似文献   

山东海洋外来入侵生物与防控对策   总被引：1，自引：0，他引：1  

田家怡  闫永利  李建庆  于祥 《海洋湖沼通报》2009,(1)

根据2004-2005年调查,山东海洋外来入侵生物至少有30种,其中,外来有害病毒1种,外来赤潮生物7种,外来养殖藻类2种,外来栽培盐生植物3种,外来动物16种.本文报道了山东海洋30种外来入侵生物及分布,分析了其危害,并提出了防控对策和建议.  相似文献   

Reconstruction of vertical thermal structure from several subsurface temperatures in the China Seas and adjacent waters     

郝佳佳  陈永利  冯俊乔  王凡 《中国海洋湖沼学报》2009,27(2):218-228

Empirical Orthogonal Function (EOF) analysis is used in this study to generate main eigenvector fields of historical temperature for the China Seas (here referring to Chinese marine territories) and adjacent waters from 1930 to 2002 (510 143 profiles). A good temperature profile is reconstructed based on several subsurface in situ temperature observations and the thermocline was estimated using the model. The results show that: 1) For the study area, the former four principal components can explain 95% of the overall variance, and the vertical distribution of temperature is most stable using the in situ temperature observations near the surface. 2) The model verifications based on the observed CTD data from the East China Sea (ECS), South China Sea (SCS) and the areas around Taiwan Island show that the reconstructed profiles have high correlation with the observed ones with the confidence level >95%, especially to describe the characteristics of the thermocline well. The average errors between the reconstructed and observed profiles in these three areas are 0.69°C, 0.52°C and 1.18°C respectively. It also shows the model RMS error is less than or close to the climatological error. The statistical model can be used to well estimate the temperature profile vertical structure. 3) Comparing the thermocline characteristics between the reconstructed and observed profiles, the results in the ECS show that the average absolute errors are 1.5m, 1.4 m and 0.17°C/m, and the average relative errors are 24.7%, 8.9% and 22.6% for the upper, lower thermocline boundaries and the gradient, respectively. Although the relative errors are obvious, the absolute error is small. In the SCS, the average absolute errors are 4.1 m, 27.7 m and 0.007°C/m, and the average relative errors are 16.1%, 16.8% and 9.5% for the upper, lower thermocline boundaries and the gradient, respectively. The average relative errors are all <20%. Although the average absolute error of the lower thermocline boundary is considerable, but contrast to the spatial scale of average depth of the lower thermocline boundary (165 m), the average relative error is small (16.8%). Therefore the model can be used to well estimate the thermocline. Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No.KZCX-3W-222; KZCX2-YW-Q11-02) and National Basic Research Program of China (No.2007CB411802; 2006CB403601)  相似文献   

天津滨海新区浅层地温能热红外遥感信息特征     

王永立 《城市地质》2012,(4):24-27

以两期Landsat7 ETM＋为基本数据源,采用单窗算法对天津滨海新区地表温度进行了反演,得到区域地表温度场的分布规律。发现地表温度变化与浅层地温能的分布有较好的对应关系,可以利用热红外遥感技术探测浅层地温能。  相似文献   

Predominance of even carbon-numbered n-alkanes from lacustrine sediments in Linxia Basin,NE Tibetan Plateau: Implications for climate change     

Yongli Wang  Xiaomin Fang  Tongwei Zhang  Yuanmao Li  Yingqin Wu  Daxiang He  Youxiao Wang 《Applied Geochemistry》2010

This study reports the first observation of predominant even C-numbered n-alkanes from sediments in the continuous lacustrine-sedimentary section (Maogou) from the Late Miocene to the Early Pliocene (13–4.4 Ma) in the Linxia Basin, NE Tibetan Plateau. The n-alkanes showed a bimodal distribution that is characterised by a centre at n-C₁₆–n-C₂₀ with maximum values at n-C₁₈ and n-C₂₇–n-C₃₁ as well as at n-C₂₉. The first mode shows a strong even C-number predominance (OEP_16–20 0.34–0.66). In contrast, the second mode has a strong odd C-number predominance (OEP_27–31 1.20–2.45). Certain types of special autochthonous bacteria are a possible source for this distribution of even C-numbered n-alkanes in lacustrine sediments. These bacteria may have a high production rate in weak oxic–anoxic and arid depositional environments, in which a variety of geochemical parameters have recorded palaeoclimate change.  相似文献   

世界石炭纪生物礁发育基本特征     

巩恩普  张永利  关长庆  常洪伦 《古地理学报》2010,12(2):127-139

石炭纪生物礁在晚古生代礁体演化序列中处于特殊地位。石炭纪是生物礁地史演化过程中一个非常关键的时期,发育的生物礁类型有:(1)叶状藻礁丘;(2)叠层石礁丘;(3)珊瑚礁;(4)Waulsortian灰泥丘;(5)Chaetetes礁丘;(6)钙质微生物—藻礁丘。石炭纪生物礁总体上表现为礁相结构、造礁群落组成及礁体建造阶段的造礁作用相对比较简单,这些都体现出生物礁在石炭纪的发展受到生物灭绝事件的影响。在以藻礁占主导地位的宾夕法尼亚亚纪,中国后生动物骨架礁发育,尤其是发育有Fomitchevella大型珊瑚礁,成为世界石炭纪生物礁的一个亮点。从石炭纪整个生物礁的发展情况来看,后生动物骨架礁与以微生物和钙藻为主导的生物礁或许是两个平行发展的礁系统,后生动物骨架礁的发展在大规模生物灭绝事件之后有明显的演化滞后现象,以钙藻和微生物为主导的造礁群落的复苏在生物灭绝事件之后更为迅速。从石炭纪生物礁古地理分布来看,石炭纪生物礁基本上分布在南北纬30°之间的区域,因此,它们代表了在相对温暖的气候条件下生长的礁体,与现代珊瑚礁的分布相近似。  相似文献