Effects of vegetation type on surface elevation change in Liaohe River Delta wetlands facing accelerated sea level rise     

Guodong Wang  Ming Wang  Ming Jiang  Xianguo Lyu  Xingyuan He  Haitao Wu 《中国地理科学(英文版)》2017,27(5):810-817

Rising sea levels threaten the sustainability of coastal wetlands around the globe. The ability of coastal marshes to maintain their position in the intertidal zone depends on the accumulation of both organic and inorganic materials, and vegetation is important in these processes. To study the effects of vegetation type on surface elevation change, we measured surface accretion and elevation change from 2011 to 2016 using rod surface elevation table and feldspar marker horizon method(RSET-MH) in two Phragmites and two Suaeda marshes in the Liaohe River Delta. The Phragmites marshes exhibited higher rates of surface accretion and elevation change than the Suaeda marshes. The two Phragmites marsh sites had average surface elevation change rates at 8.78 mm/yr and 9.26 mm/yr and surface accretion rates at 17.56 mm/yr and 17.88 mm/yr, respectively. At the same time, the two Suaeda marsh sites had average surface elevation change rates at 5.77 mm/yr and 5.91 mm/yr and surface accretion rates at 13.42 mm/yr and 14.38 mm/yr, respectively. The elevation change rates in both the Phragmites marshes and the Suaeda marshes in the Liaohe River Delta could keep pace and even continue to gain elevation relative to averaged sea level rise in the Bohai Sea reported by the 2016 State Oceanic Administration, People's Republic of China projection(2.4–5.5 mm/yr) in current situations. Our data suggest that vegetation is important in the accretionary processes and vegetation type could regulate the wetland surface elevation. However, the vulnerability of coastal wetlands in the Liaohe River Delta need further assessment considering the accelerated sea level rise, the high rate of subsidence, and the declining sediment delivery, especially for the Suaeda marshes.  相似文献   

A comparative study in tritium in precipitation in four Chinese cities with different climate regimes     

Yuchuan Meng  Guodong Liu 《Environmental Earth Sciences》2017,76(6):249

Four GNIP sites, Hong Kong, Kunming, Shijiazhuang and Urumqi with relatively complete tritium records, have been selected to determine the characteristics of tritium in precipitation in different climatic and geographical regions in China. The highest concentration, 559 TU, was measured at Hong Kong in April 1963 and resulted from Soviet thermonuclear testing. During 1985–2004, tritium values decreased substantially due to the radioactive decay and the vapor exchange between the atmosphere and ocean. During this period, tritium concentrations tended to be much higher in inland regions than in coastal regions. This difference may be explained by the continental effect and the inland continental thermonuclear testing. Stratosphere-to-troposphere exchange is the important driver for the timing of tritium seasonal peak at Urumqi and Kunming, but this mechanism is less pronounced at Hong Kong and Shijiazhuang. This offset indicates that the complex stratosphere–troposphere exchange process appears to be neither seasonally nor geographically uniform. The amount effect was only observed at the Hong Kong, indicating different tritium sources than at the other locations. Therefore, air masses influencing tritium in precipitation are more complex in inland region than in coastal region.  相似文献   

Vertical distribution of snow cover and its relation to temperature over the Manasi River Basin of Tianshan Mountains,Northwest China     

Wenlong Zheng  Jinkang Du  Xiaobing Zhou  Mingming Song  Guodong Bian  Shunping Xie  Xuezhi Feng 《地理学报(英文版)》2017,27(4):403-419

How snow cover changes in response to climate change at different elevations within a mountainous basin is a less investigated question. In this study we focused on the vertical distribution of snow cover and its relation to elevation and temperature within different elevation zones of distinct climatology, taking the mountainous Manasi River Basin of Xinjiang, Northwest China as a case study. Data sources include MODIS 8-day snow product, MODIS land surface temperature (LST) data from 2001 to 2014, and in situ temperature data observed at three hydrological stations from 2001 to 2012. The results show that: (1) the vertical distribution of snow areal extent (SAE) is sensitive to elevation in low (<2100 m) and high altitude (>3200 m) regions and shows four different seasonal patterns, each pattern is well correspondent to the variation of temperature. (2) The correlation between vertical changes of the SAE and temperature is significant in all seasons except for winter. (3) The correlation between annual changes of the SAE and temperature decreases with increasing elevation, the negative correlation is significant in area below 4000 m. (4) The snow cover days (SCDs) and its long-term change show visible differences in different altitude range. (5) The long-term increasing trend of SCDs and decreasing trend of winter temperature have a strong vertical relation with elevation below 3600 m. The decreasing trend of SCDs is attributed to the increasing trend of summer temperature in the area above 3600 m.  相似文献   

微破裂弹性回跳模型和一次地震的三种波     

赵复垣  张国栋  王泽之 《华南地震》2009,29(4):64-71

经典弹性回跳模型是历史上最有影响的地震模型之一．热力学弹性回跳模型对经典弹性回跳模型进行了合理的补充。根据存在着震前超低频应力一密度波和临震微破裂波的设想．进一步补充了热力学弹性回跳模型．新模型或可称为“微破裂弹性回跳模型”。这个模型与很多实测结果符合得很好。因为大多数地震都要经历应变累积、微破裂和主破裂三个阶段．所以,一次地震一般都会先后出现三种不同类型的波,即：超低频应力一密度波（应变波）、微破裂波以及普通地震波。这一认识对深入理解地震现象以及对地震的监测和预警都是有意义的．  相似文献   

从汶川地震看震前的“微破裂波”   总被引：1，自引：0，他引：1  

赵复垣  张国栋 《国际地震动态》2009,(6):19-23

根据对包括汶川大地震等一些实测资料的分析,并借用断裂力学和断裂物理的概念,可以认为存在一种震前出现的“微破裂波”。即,震前地层中发生的“微破裂”过程可以产生“微破裂波”。由于破裂过程的微观复杂性,微破裂波中有电磁波、声波和重力波等不同成分,而且有频率覆盖范围宽、信号相对较弱等特点。微破裂波一般都产生于主破裂之前约1～10天之内。只要有合适的有着足够高灵敏度和足够宽的频率响应能方的仪器系统,就可能探测到微破裂波,也就获取了一种重要的有临震预警意义的信息。  相似文献   

北江流域氮收支估算   总被引：2，自引：0，他引：2  

陈法锦  贾国东 《热带地理》2009,29(1)

根据2006年北江流域的基本统计数据和相关参数,对该地区氮的收支进行了估算和环境影响分析.2006年北江流域的氮输入量为39.52×104 t,单位国土面积接收的氮量为84.61 kg/hm2·a,稍高于全国和长江流域,也高于世界一些大河流域.在氮的输出中,约38.61﹪的氮通过珠江口输送到中国南海,27.80﹪的氮通过反硝化和9.13﹪的氮通过氨挥发进入大气,剩余24.46﹪的氮储存在流域内.研究发现,北江流域的主要氮输入源均与农业活动有关,氮输入源分布的地区差异较大,单位面积接收总氮量主要受经济发达程度的影响.  相似文献   

基于随机森林的土地利用分类与景观格局分析     

李敏  刘国栋  谭凌 《地理空间信息》2022,20(2):51-56

基于景观格局分析方法,分别选取8个反映景观格局类型和6个反映景观水平格局指数用于探索土地利用变化状况.实验结果表明:①基于选择合适的训练样本下,对3期遥感影像采用随机森林的监督分类方法,总体精度均在94％以上,kappa系数均为90％以上;②综合来看,研究期内建设用地为优势景观类型.研究区斑块数量增加,破碎化程度有所加...  相似文献   

2-取代-5-氟脲嘧啶的_β-D -木糖苷的合成(英文)     

张建国  王铎  张国栋  孙昌俊  戚聿新 《中国海洋大学学报(自然科学版)》1999,(Z1)

通过相转移催化法或ｋｏｅｎｉｇｓｋｎｏｒｒ’ｓ 反应合成了１１ 种未见文献报道的２取代５氟尿嘧啶的βＤ木糖苷,结构经ＩＲ、ＨＮＭＲ、ＭＳ或元素分析证实,初步生物实验表明具有一定程度的抗癌性。  相似文献   

大庆油田齐家水源地取水设备腐蚀与堵塞特征及形成机理分析   总被引：2，自引：0，他引：2  

李东艳  周志祥 《现代地质》1999,13(4):477-480

为查明齐家水源地取水设备腐蚀与堵塞的机理 ,在现场测试地下水 Eh值和 p H值的基础上 ,采集了地下水、腐蚀管材及沉砂管中沉积物样品。利用微生物分析、X衍射分析、显微镜鉴定和扫描电镜分析等手段 ,结合水文地球化学特征研究 ,认为滤水管的石墨化及防腐泵铸铁外壳的腐蚀为宏观腐蚀电池电化学腐蚀 ;滤水管、扬水管内壁发生了厌氧硫酸盐还原菌电化学腐蚀和厌氧 H2 O-CO2 电化学腐蚀。堵塞物大部分是腐蚀产物 ,堵塞伴随腐蚀而产生。该水源地水井堵塞的机理与国内外普遍认同的富 Fe2 +地下水氧化结垢使水井堵塞的机理不同。  相似文献   

Research and Application of In‐seam Seismic Survey Technology for Disaster‐causing Potential Geology Anomalous Body in Coal Seam     

TENG Jiwen  LI Songying  JIA Mingkui  LIAN Jie  LIU Honglei  LIU Guodong  WANG Wei  Volker SCH?PE  FENG Lei  YAO Xiaoshuai  WANG Kang  YAN Yafen  ZHANG Wanpeng 《《地质学报》英文版》2020,94(1):10-26

In order to effectively detect potential geology anomalous bodies in coal bearing formation, such as coal seam thickness variation, small faults, goafs and collapse columns, and provide scientific guidance for safe and efficient mining, the SUMMIT-II EX explosion-proof seismic slot wave instrument, produced by German DMT Company, was used to detect the underground channel wave with the help of transmission method, reflection method and transflective method. Region area detection experiment in mining face had been carried out thanks to the advantage of channel wave, such as its great dispersion, abundant geology information, strong anti-interference ability and long-distance detecting. The experimental results showed that: (1) Coal seam thickness variation in extremely unstable coal seam has been quantitatively interpreted with an accuracy of more than 80% generally; (2) The faults, goafs and collapse columns could be detected and predicted accurately; (3) Experimental detection of gas enrichment areas, stress concentration regions and water inrush risk zone has been collated; (4) A research system of disaster-causing geology anomalous body detection by in-seam seismic survey has been built, valuable and innovative achievements have been got. Series of innovation obtained for the first time in this study indicated that it was more effective to detect disaster-causing potential geology anomalies by in-seam seismic survey than by ground seismic survey. It had significant scientific value and application prospect under complex coal seam conditions.  相似文献