黄河三角洲湿地资源地质环境评价与保护对策研究          下载免费PDF全文

王强  张红军  张太平  王薇  刘洋  赵慧  王奎峰  张瑞华 《山东国土资源》2018,34(5)

黄河三角洲是中国唯一一块保存最完整、最典型、最年轻的湿地生态系统,由于其地理位置优越、自然资源丰富等特点,在国际上备受关注。该文在已有资料分析、现场地质调查、遥感数据分析的基础上,构建了黄河三角洲湿地资源地质环境评价指标体系,采用定量与定性相结合的方法,将黄河三角洲湿地地质环境质量分为5个等级(优、良、一般、较差和差),研究结果表明,该地区19个县(市、区)中湿地地质环境资源质量为良的有8个,质量一般的为11个,总体处于健康-疾病的临界状态。并基于以上研究成果,针对性地提出了黄河三角洲湿地资源保护对策。  相似文献   

苏北浅滩养殖筏架附生绿藻入海过程在黄海绿潮形成中的作用   总被引：3，自引：0，他引：3  

张清春  孔凡洲  颜天  于仁成  胡晓坤  苗辉  周名江 《海洋与湖沼》2018,49(5):1014-1020

本研究采用现场定量观测为主的研究方法,在2017年5月期间对苏北浅滩竹根沙收紫菜养殖筏架作业过程进行跟踪调查;对养殖筏架绠绳附生绿藻自然脱落和收筏架作业过程人为刮落附生绿藻,以及收筏架作业前后入海的漂浮绿藻生物量进行定量观测。结果表明:筏架绳附生绿藻自然脱落率低,为3.58%±0.78%;收筏架作业过程中绠绳上刮落绿藻生物量为(12±3)kg湿重/根,由此估算2017年整个苏北浅滩刮落的生物量估算可达到万吨湿重;收筏架作业后海域漂浮绿藻生物量是作业前的7.6倍。研究结果进一步明确了收筏架作业过程中人为刮落绿藻是目前筏架附生绿藻最主要的入海方式。刮落绿藻是海水中漂浮绿藻的主要来源,其生物量对南黄海绿潮的规模大小有重要的影响。研究结果为绿潮防控措施的制定和实施提供科学依据。  相似文献   

闽三角海域赤潮发生的时空特征     

邹晓梅  林广发  陈志彪 《海洋科学》2018,42(11):110-117

赤潮是海洋生态系统异常的重要指标。本文收集1986～2017年闽三角海域的赤潮事件,基于GIS技术分析赤潮的时空分布特征。结果表明:32年来,闽三角海域赤潮发生98次,赤潮高发区在厦门西海域、同安湾和泉州湄洲湾海域;闽三角海域赤潮年际发生次数呈波动变化,一年中赤潮高发期集中在5～8月;中肋骨条藻、角毛藻及旋链角毛藻是闽三角海域的赤潮优势种,具有一定的区域分布特征;有毒赤潮事件发生频率有增加趋势。本文系统性地总结了闽三角海域赤潮时空特征,为该区域的赤潮风险分析和预防提供依据。  相似文献   

SWAT模型在土地利用/覆被变化剧烈地区的改进与应用     

金鑫  金彦香  杨登兴 《地球信息科学学报》2018,20(8):1064-1073

人口增长、气候变化、制度变迁、城市化等均会导致土地利用/覆被的变化,进而引起流域水文过程（截留、入渗、蒸散发和地下水补给等）和水循环过程的改变。当前,由于逐年土地利用/覆被数据获取困难、水文模型本身计算缺陷等问题,所有在流域尺度上开展的借助水文模型进行的土地利用/覆被变化影响下的水文模拟研究都存在一个共同缺点,就是采用的水文模型并不能逐年调用土地利用/覆被数据,即水文模型无法真实体现或模拟土地利用/覆被的时空变化。SWAT作为一个广泛应用的分布式水文模型,在其模拟期内,不能逐年调用土地利用/覆被数据,即在进行水文模拟时忽略了土地利用/覆被时间上的变化,这可能会影响其在土地利用/覆被变化剧烈地区（如黑河中游）的应用。黑河流域是典型的内陆河流域,也是中国西北地区第二大内陆河流域。黑河中游是黑河流域的径流耗散区。本文针对SWAT模型在考虑土地利用/覆被变化时的缺点,对其进行了改进并开发出能够逐年调用土地利用/覆被数据的LU-SWAT模型。在土地利用/覆被变化剧烈的黑河中游对SWAT和LU-SWAT模型的径流模拟效果进行比较,发现LU-SWAT模型更适用于黑河中游水循环模拟。  相似文献   

Long‐term variations and temporal scaling of hydroclimatic time series with focus on the German part of the Elbe River Basin          下载免费PDF全文

D. Markovic  M. Koch 《水文研究》2014,28(4):2202-2211

Long‐term variations and temporal scaling of mean monthly time series of river flow, precipitation, temperature, relative humidity, air pressure, duration of bright sunshine, degree of cloud cover, short wave radiation, wind speed and potential evaporation within or in vicinity of the German part of the Elbe River Basin are analyzed. Statistically significant correlations between the 2–15 year scale‐averaged wavelet spectra of the hydroclimatic variables and the North Atlantic Oscillation‐ and Arctic Oscillation index are found which suggests that such long‐term patterns in hydroclimatic time series are externally forced. The Hurst parameter estimates (H) based on the Detrended Fluctuation Analysis (DFA) indicate persistence for discharge, precipitation, wind speed, air pressure and the degree of cloud cover, all having an annual cycle and a broad low‐frequency distribution. Also, DFA H parameter estimates are higher for discharge than for precipitation. The major long‐term quasi‐periodic variability modes of precipitation detected using Singular Spectrum Analysis coincide with those detected in the discharge time series. Upon subtraction of these low‐frequency quasi‐periodic modes, the DFA H parameter estimates suggest absence of the persistence for both precipitation and discharge. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Regional extreme‐dry‐spell frequency analysis using the L‐moments method in the middle reaches of the Yellow River Basin,China          下载免费PDF全文

Dun‐Xian She  Jun Xia  Dan Zhang  Ai‐Zhong Ye  Aditya Sood 《水文研究》2014,28(17):4694-4707

In this research, the regional extreme‐dry‐spell frequency in the middle reaches of the Yellow River Basin (YRB) is studied by the L‐moments method. The research area has been divided into three subregions (regions 1, 2 and 3), which have been identified as homogenous regions. The results of a goodness‐of‐fit test indicate that a generalized normal distribution is the optimal regional model for regions 1 and 2 whereas a generalized Pareto distribution is the optimal regional model for region 3. The return period analysis figures out that the maximum length‐of‐dry‐spell (MxDS) values increase from south to north in the southern part and increase from northeast to southwest in the northern part of the middle reaches of the YRB under different return periods. The increments of quantiles of dry spell under different return levels indicate that drought risk in region 1 is higher than that in regions 2 and 3. The analysis of the occurrence day of MxDS shows that MxDS mostly occurred during winter of 1998 and spring of 1999 in most stations during the considered period. By comparing summer MxDS events, it can be found that mean MxDS values have slightly increased in regions 1 and 2 during the last five decades. The maximum mean MxDS values appeared in the 2000s for regions 1 and 2 and in the 1990s for region 3. The atmospheric circulation shows that the positive anomaly centre in the west of North China, negative anomaly centre in the east of North China and the strong western Pacific subtropical high led to the decrease of precipitation in North China during the summer of 1997. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Suspended sediment and total dissolved solid yield patterns at the headwaters of Urumqi River,northwestern China: a comparison between glacial and non‐glacial catchments          下载免费PDF全文

Wenhua Gao  Shu Gao  Zhongqin Li  X. X. Lu  Mingjun Zhang  Shengjie Wang 《水文研究》2014,28(19):5034-5047

In order to understand the differences in the suspended sediment and total dissolved solid (TDS) yield patterns between the glacial and non‐glacial catchments at the headwaters of Urumqi River, northwestern China, water samples were collected from a glacier catchment and an empty cirque catchment within the region, during three melting seasons from 2006 to 2008. These samples were analyzed to estimate suspended sediment and TDS concentrations, fluxes and erosion rates in the two adjoining catchments. There were remarked differences in suspended sediment and TDS yield patterns between the two catchments. Suspended sediment concentrations were controlled mainly by the sediment source, whereas TDS concentrations were primarily related to the hydrologic interaction with soil minerals. Generally, the glacial catchment had much higher suspended sediment and TDS yields, together with higher denudation rates, than the non‐glacial catchment. Overall, glacial catchment was mainly dominated by physical denudation process, whereas the non‐glacial catchment was jointly influenced by physical and chemical denudation processes. The observed differences in material delivery patterns were mainly controlled by the runoff source and the glacial processes. The melting periods of glacier and snow were typically the most important time for the suspended sediment and TDS yields. Meanwhile, episodic precipitation events could generate disproportionately large yields. Subglacial hydrology dynamics, glaciers pluck and grind processes could affect erodibility, and the large quantities of dust stored on the glacier surface provided additional sources for suspended sediment transport in the glacial catchment. These mechanisms imply that, in response to climate change, the catchment behaviour will be modified significantly in this region, in terms of material flux. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Pre‐ and post‐impoundment nitrogen in the lower Missouri River          下载免费PDF全文

Dale W. Blevins  Donald H. Wilkison  Shelley L. Niesen 《水文研究》2014,28(4):2535-2549

Large water‐sample sets collected from 1899 through 1902, 1907, and in the early 1950s allow comparisons of pre‐impoundment and post‐impoundment (1969 through 2008) nitrogen concentrations in the lower Missouri River. Although urban wastes were not large enough to detectably increase annual loads of total nitrogen at the beginning of the 20^th century, carcass waste, stock‐yard manure, and untreated human wastes measurably increased ammonia and organic‐nitrogen concentrations during low flows. Average total‐nitrogen concentrations in both periods were about 2.5 mg/l, but much of the particulate‐organic nitrogen, which was the dominant form of nitrogen around 1900, has been replaced by nitrate. This change in speciation was caused by the nearly 80% decrease in suspended‐sediment concentrations that occurred after impoundment, modern agriculture, drainage of riparian wetlands, and sewage treatment. Nevertheless, bioavailable nitrogen has not been low enough to limit primary production in the Missouri River since the beginning of the 20^th century. Nitrate concentrations have increased more rapidly from 2000 through 2008 (5 to 12% per year), thus increasing bioavailable nitrogen delivered to the Mississippi River and affecting Gulf Coast hypoxia. The increase in nitrate concentrations with distance downstream is much greater during the post‐impoundment period. If strategies to decrease total‐nitrogen loads focus on particulate N, substantial decreases will be difficult because particulate nitrogen is now only 23% of total nitrogen in the Missouri River. A strategy aimed at decreasing particulates also could further exacerbate land loss along the Gulf of Mexico, which has been sediment starved since Missouri River impoundment. In contrast, strategies or benchmarks aimed at decreasing nitrate loads could substantially decrease nitrogen loadings because nitrates now constitute over half of the Missouri's nitrogen input to the Mississippi. Ongoing restoration and creation of wetlands along the Missouri River could be part of such a nitrate‐reduction strategy. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.  相似文献   

大陆架科学钻探CSDP-2井的垂直地震剖面测量   总被引：1，自引：0，他引：1       下载免费PDF全文

吴志强  祁江豪  张训华  郭兴伟  丘学林  张雪飞  谭云龙  黄聿晓  李文强  庞玉茂 《地球物理学报》2019,62(9):3492-3508

南黄海海相地层的地震波场特征和层位标定一直是困扰地震勘探的重要问题.为了近距离、高精度和高分辨率地观测井周围构造特征和岩石性质引起的波场变化，为地震资料的采集、处理与解释提供地震波衰减规律、速度与层位标定等信息，对大陆架科学钻探CSDP-2井实施了近零偏移距垂直地震剖面（VSP）观测.针对海相地层顶部强反射界面地震波穿透难的问题，采用了大容量气枪震源并设计了气枪阵列组合方式，提高了激发地震波的能量，获得了强反射界面之下清晰的PP、PS下行波和上行波信号.采用了三分量偏振合成、组合滤波和波场分离等处理方法，对VSP观测数据进行处理，获得了海相三叠系—志留系的精细的纵波、横波速度结构和地层吸收因子等物性数据，建立了钻井地层、测井、VSP上行波和多道地震剖面对应关系，实现了不同尺度的地质和地球物理属性资料的有效衔接，标定了钻井地质剖面上各深度地质体的地震反射特性，厘定了过井地震剖面上反射同相轴的地质属性.此次观测取得的纵波、横波速度信息，成为建立南黄海海相地层速度模型主要的资料来源，也是地震资料的岩性反演处理不可缺少的信息.  相似文献   

Cathodoluminescence and Trace Element Composition of Scheelite from the Middle-Lower Yangtze River Metallogenic Belt (MLYB): Implications for Mineralization and Exploration     

NIE Liqing  ZHOU Taof  CHEN Xuefeng  WANG Fangyue  XIAO Xin 《《地质学报》英文版》2020,94(6):1977-1996

The Middle–Lower Yangtze River Metallogenic Belt (MLYB) is known to contain abundant copper and iron porphyry-skarn deposits, with an increasing number of tungsten deposits and scheelite in Fe–Cu deposits being discovered in the MLYB during recent decades. The ore genesis of the newly-discovered tungsten mineralization in the MLYB is poorly understood. We investigate four sets of scheelite samples from tungsten, iron and copper deposits, using CL imaging and LA–ICP–MS techniques to reveal internal zonation patterns and trace element compositions. The REE distribution patterns of four studied deposits show varying degrees of LREE enrichment with negative Eu anomalies. The oxygen fugacity of ore-forming fluid increased in Donggushan, while the oxygen fugacity of ore-forming fluid decreased in Ruanjiawan, Guilinzheng and Gaojiabang. The scheelites from the Donggushan, Ruanjiawan, Guilinzheng and Gaojiabang deposits show enrichment in LREEs and HFSE, with Nb/La ratios ranging from 1.217 to 52.455, indicating that the four tungsten deposits are enriched in the volatile fluorine. A plot of (La/Lu)N versus Mo/δEu can be used to distinguish quartz vein type, porphyry and skarn tungsten deposits. This study demonstrates that scheelite grains can be used to infer tungsten mineralization and are effective in identifying magmatic types of tungsten deposits in prospective mining sites.  相似文献