不同出露时间下洞庭湖洲滩土壤及生态系统呼吸特征   总被引：1，自引：0，他引：1  

周延  靖磊  杨萌  史林鹭  吕偲  雷光春 《湖泊科学》2018,30(6):1664-1671

于2015年1月洞庭湖枯水期，针对不同出露时间下的洲滩，调查其土壤理化性质，并利用LI-8100便携式二氧化碳气体分析仪监测其生态系统呼吸.结果表明：在洞庭湖枯水期，洲滩出露后，洲滩土壤有机质、硝态氮、铵态氮和全氮含量随出露时间增长而先升高后降低.土壤溶解性有机碳含量是影响洞庭湖枯水期洲滩生态系统呼吸强度的最重要影响因子.溶解性有机碳含量随出露时间增长而提高，洲滩生态系统呼吸强度随之提高，并在洲滩出露约60天后达到最高值.出露洲滩生态系统呼吸通量均值为0.72±0.55 μmol/（m²·s），超过杨树林地、芦苇地和农田地，成为洞庭湖区冬季CO₂排放最活跃的区域.  相似文献   

The wider context of the Lower Jurassic Toarcian oceanic anoxic event in Yorkshire coastal outcrops,UK     

Nicolas Thibault  Micha Ruhl  Clemens V. Ullmann  Christoph Korte  David B. Kemp  Darren R. Gröcke  Stephen P. Hesselbo 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(3):372-391

The Toarcian Oceanic Anoxic Event (T-OAE, ～183 Ma) was characterized by enhanced carbon burial, a prominent negative carbon-isotope excursion (CIE) in marine carbonate and organic matter, and numerous geochemical anomalies. A precursor excursion has also been documented at the Pliensbachian/Toarcian boundary, but its possible causes are less constrained. The T-OAE is intensively studied in the Cleveland Basin, Yorkshire, UK, whose sedimentary deposits have been litho-, bio- and chemostratigraphically characterised. Here, we present new elemental data produced by hand-held X-ray fluorescence analysis to test the expression of redox-sensitive trace metals and detrital elements across the upper Pliensbachian to mid-Toarcian of the Cleveland Basin. Detrital elemental concentrations (Al, Si, Ti, Zr) are used as proxies for siliciclastic grain content and thus, sea-level change, which match previous sequence stratigraphic interpretations from the Cleveland Basin. The timescale of the event is debated, though our new elemental proxies of relative sea level change show evidence for a cyclicity of 350 cm that may be indicative of ～405 kyr eccentricity cycles in Yorkshire. Trends in total organic carbon and redox-sensitive elements (S, Fe, Mo, As) confirm scenarios of widespread ocean deoxygenation across the T-OAE. The correlation of comparable trends in Mo across the T-OAE in Yorkshire and the Paris Basin suggests a similar oceanic drawdown of this element accompanying widespread anoxia in the two basins. Data from Yorkshire point to a transgressive trend at the time of the Mo drawdown, which contradicts the “basin restriction” model for the euxinic conditions that characterise the CIE interval.  相似文献   

A predictive model for well loss using fuzzy logic approach     

Abdüsselam Altunkaynak 《水文研究》2010,24(17):2400-2404

Simple methods for calculating well losses are important for well design and optimization of groundwater source operation. Well losses arise from both laminar flow within the aquifer and turbulent flow within the well, and are often ignored in theoretical aquifer test analysis. The Jacob ( 1947 ) and Rorabaugh ( 1953 ) techniques for predicting well losses are widely used in the literature; however, inherent in these techniques are the assumptions of linearity, normality and homoscedascity. In the Rorabaugh technique, prior knowledge, or prediction of, the parameters A, C and n is required for calculation of well losses. Unfortunately, as of yet, no method for adequately obtaining these parameters without experimental data and linear regression exist. For these reasons, the Rorabaugh methodology has some practical and realistic limitations. In this paper, a fuzzy logic approach is employed in the calculation of well losses. An advantage of the fuzzy logic approach is that it does not make any assumptions about the form of the well loss functionality and does not require initial estimates for the calculation of well losses. Results show that the fuzzy model is a practical alternative to the Rorabaugh technique, producing lower errors (mean absolute error, mean square error and root mean square error) relative to observed data, for the case presented, comparatively to the Rorabaugh model. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

间断性阶梯抽水试验求解水文地质参数解析法   总被引：1，自引：1，他引：0       下载免费PDF全文

滕凯 《水文》2017,37(2):59-63

针对利用间断性阶梯流量抽水试验资料求解水文地质参数采用试算法、特殊标准曲线比对法及线性回归法等存在的计算过程繁复、人为误差难免、图表束缚严重等问题,采用优化拟合方法,在工程适应参数范围内,通过对以级数表示的泰斯井函数的简单函数替代,并依据抽水试验降深时间关系曲线上的选点,采用降深比值法,经对间断性阶梯流量抽水井流函数的整理推导,获得了可直接完成相关水文地质参数求解的一元二次方程,求解过程简捷直观,便于实际工程应用。精度分析表明,在工程适用参数范围内,最大相对误差小于2%,完全满足实际工程的计算精度要求。  相似文献   

地下水位变化对透—阻型岩溶塌陷影响的分析     

陶小虎  赵坚  Xiaoming Wang  Ming Ye  Roger Benito Pacheco Castro 《中国岩溶》2017,36(6):777-785

文章从一维地下水运动和渗透力学的角度,分析比较潜水位上升与承压水位下降对岩溶地区透—阻型盖层中阻水层渗透稳定性的影响,重点讨论了承压水位下降速度(降速)与下降深度（降深）对阻水层中渗透坡降的影响,结果表明:地下水位变化（潜水位上升或承压水位下降）产生的非稳定渗流不利于岩溶洞穴开口上方阻水层的稳定,承压水位的下降对岩溶开口附近处阻水层中渗透力的影响远大于潜水位的变化;在承压层水位最大降深确定的条件下,承压水位下降速度愈快,岩溶开口附近处阻水层中向下渗透力愈大。因此,在覆盖型岩溶地区抽取地下水时,为了减缓或避免覆盖型塌陷的发生,应同时控制好最大降深和最大开采速度。   相似文献   

井损对水文地质参数计算的影响     

高海东 《中国煤炭地质》2010,(3):24-27

通过分析抽水试验过程中井损产生的原因及确定方法,运用水位动态变化过程中的井损计算方法,对乌兰陶勒盖水源地WL6号孔的抽水试验资料的井损计算程序进行了说明,并提出了该水源地理想降深与实际降深的经验公式。利用Aqui Test软件,分别计算了忽略井损和考虑井损两种情况下潜水(承压水)抽水井渗透系数及给水度(贮水率),从计算结果来看,计算井损、修正降深所得的各参数的值要比不考虑井损的值大;井损对潜水的抽水试验资料的影响要比承压水的大。  相似文献   

兴隆庄井田奥灰水单孔小口径抽水降距问题分析     

杨德善 《中国煤炭地质》2010,(3):32-33

针对岩溶发育的大水矿区,在进行小孔径抽水试验工作时,现有的国产压风机虽然尽了最大机械能力,但水位的降低值仍然达不到规范的质量要求,不得不将小孔径抽水试验改为大口径或孔组抽水的情况,采取了加长风管长度,用进口在压风机的方法,完成了兴隆庄井田O2-7号水文孔的小孔径抽水试验工作。从抽水试验的曲线来看,该方法切实可行,有一定推广价值。  相似文献   

Identification of aquifer parameters from residual drawdowns: an optimization approach     

《水文科学杂志》2013,58(6):1139-1148

Abstract

An optimization method based on nonlinear least squares is proposed for the identification of aquifer transmissivity and two storage coefficients, one for the pumping phase and the other for the recovery phase, using only residual drawdowns at an observation well. The method is applicable irrespective of whether pumping and recovery storage coefficients are the same or are different and the argument of well function during recovery is less than or greater than 0.01. The method can check for the changed value of storage coefficient during the recovery phase and can quantify this change. Use of the method is illustrated through examples, which show that the parameters are estimated reliably.  相似文献   

库水位升降作用下大型堆积体边坡变形破坏预测     

董金玉  杨继红  孙文怀  黄志全  王东  杨国香 《岩土力学》2011,32(6):1774-1780

库岸边坡的变形破坏及稳定性研究是目前国内外研究的热点之一。基于水电站库区一大型堆积体边坡,通过现场原位直剪试验获取岩土体的力学参数,利用岩土数值分析FLAC3D软件,考虑了堆积体与基岩基覆接触带介质的应变软化特性,对水库蓄水和下降过程中边坡的变形破坏特征进行了分析预测。结果表明,在库水升降作用下变形主要发生在堆积体内部;根据堆积体的变形特征可分为3个区：前缘牵引变形区,变形量最大;中间过渡区,变形量最小;后缘被牵引变形区,变形量介于前缘和中间之间。模拟过程中,在坡体的不同位置设置位移监测点,得到了蓄水和水位下降过程中各监测点的位移时程曲线,监测结果显示,水位下降时堆积体前缘易形成局部失稳。通过剪应变增量判断堆积体边坡在库水作用下可形成2个潜在的滑动破坏面  相似文献   

地下水加坡理论在井筒涌水量预算中的应用     

武克俭  李文彬 《中国煤炭地质》2008,(11):24-25

地下水加坡理论可有效的消除抽水试验引起的无效降深,结合云驾岭煤矿井筒检查孔抽水试验资料,对该井简检查孔涌水量进行了预算,预算副井筒啮。砂岩含水层涌水量为523．03m^3／h,实际涌水量为455m^3／h．误差率14．95％,可见运用加坡理论计算的矿井涌水量与井筒实际涌水量基本相符。  相似文献