共查询到19条相似文献，搜索用时 140 毫秒
1.
淹水对菖蒲萌发及幼苗生长的影响 总被引：2，自引：0，他引：2
应用盆栽试验方法,研究了菖蒲在不同淹水深度下的萌发和幼苗生长.试验共设20、40、60、80、100和120 cm等6个处理,处理时间为86 d.结果表明:(1)不同淹水深度对菖蒲萌发和幼苗有不同程度的影响,在持续完全淹水条件下,菖蒲幼苗的萌发率仅为淹水20 cm条件下的1/3,幼苗的平均高度为淹水20 cm条件下的1/3左右;(2)菖蒲幼苗叶片长度、宽度、叶片面积和基茎随淹水深度增加而减小,叶片数量和叶片含水率随淹水深度增加而增大;(3)在试验的27 d、54 d、86 d,各淹水深度植物的根、茎、叶及总生物量都比淹水20 cm有不同程度的降低,并随淹水时间的延长,各淹水深度条件下的生物量差别增大.在不同淹水深度条件下,根、茎和叶生物量增量均表现为茎的最多,叶的次之,根的最少;(4)菖蒲幼苗在水深为100-120 cm的逆境条件下时,叶片细胞膜脂过氧化加剧,细胞质膜透性增加;(5)菖蒲幼苗叶片的叶绿素a、b含量和类胡萝卜素(Car)含量随淹水深度的增加而下降;(6)Fv/Fm、ETR、qP随淹水深度的增加而下降,长时间(54-86 d)完全淹水(水深100-120 cm)对菖蒲幼苗光合系统PSⅡ有显著影响,影响菖蒲幼苗PSⅡ的非循环光合电子传递速率,天线色素吸收的光能用于光化学电子传递的份额减少,参与CO2固定的电子减少;qN在54 d、86 d的都有不同程度的增加,菖蒲叶片PSⅡ系统没有遭到破坏. 相似文献
2.
地下水位在非淹水期对湿地植物的生长影响较大,但目前相关研究十分缺乏.本文选择鄱阳湖典型植被灰化薹草(Carex cinerascens)为研究对象,研究不同地下水位(地下水位埋深10、20、40、80和120 cm)对灰化薹草形态指标、地上生物量和生理指标的影响.结果表明,随着地下水位埋深的增加,灰化薹草的株高、叶长和生物量均显著降低,地下水位10 cm处理组的灰化薹草生物量为0.371±0.017 g,为地下水位120 cm处理组(0.084±0.004 g)的4.4倍;处理组间灰化薹草叶片中超氧化物歧化酶活性、过氧化物酶活性、游离脯氨酸含量和叶绿素含量均存在显著差异,其中游离脯氨酸含量由地下水位10 cm处理组的6.29±0.70μg/g增加到地下水位120 cm处理组的8.54±1.37μg/g,表明随着地下水位埋深的增加,灰化薹草面临一定程度的干旱胁迫.灰化薹草的生理生态响应综合表明,地下水位埋深20 cm以内适宜灰化薹草的生长,地下水位埋深80 cm以上的干旱胁迫会阻碍灰化薹草的生长. 相似文献
3.
以洞庭湖典型湿地植物辣蓼为目标植物,短尖苔草为邻近植物,通过控制实验研究不同水位(30、0和-30 cm)和竞争(无竞争、全部竞争、地上竞争和地下竞争)模式下目标植物生长及生态化学计量特征的变化.结果表明:水位处理显著影响不同竞争模式下的生物量积累,辣蓼生物量随水位增加显著降低;-30 cm水位无竞争模式下生物量最大,为10.84±1.52 g.在30 cm和0 cm水位梯度下,不同竞争模式下的生物量间无显著差异.但-30 cm水位下,地下竞争模式下的辣蓼生物量积累较全竞争模式和地上竞争模式下显著增多,说明非胁迫条件下,辣蓼和苔草的竞争以地上竞争为主.水位处理对辣蓼叶片、茎和根的氮、磷含量影响显著,30 cm水位下,叶片氮、磷含量显著高于其他水位下的含量.在-30cm水位下,叶片C∶N和C∶P显著高于其他水位下的比值,分别为48.08±3.85、590.3±43.4.相比于对照处理(无竞争),竞争作用下的辣蓼总氮含量降低,而C∶N值增加,N∶P值降低,这可能是因为竞争作用导致辣蓼对氮的吸收减少所致. 相似文献
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有机质含量和含水率对泥炭及泥炭质土(简称泥炭土)的力学性质及工程特性影响都很大,但现有的规范、规程及标准对高有机质含量土的含水率(ω)及有机质含量(wu)测定标准不明确,各单位测试结果差异较大。为明确高有机质含量土的ω及wu测定标准,开展不同灼烧温度及灼烧时间下的测试试验。滇池湖相沉积土的场地一般都有3~5层层状分布的泥炭土,现对不同埋深的5层泥炭土进行从低至高围压下的三轴固结不排水(CU)试验,探究不同埋深及围压下其应力-应变的变化规律及演化机理。试验发现:泥炭土随围压增大应力-应变关系曲线呈现“分层”现象,最大偏应力对应的应变随深度增加而减小,线型随围压和土样埋深而发生改变,孔隙压力系数总体随着深度的增加而减小,并提出CU试验泥炭土破坏应变控制标准。以上研究进一步加深了对泥炭土力学特性的认识,也为明确ω及wu的测定标准提供了试验依据。 相似文献
6.
近年来,受全球变化及高强度人为干扰的影响,湿地退化严重(洞庭湖湿地枯水期提前、枯水期水位持续降低和浅水洼地减少),导致洞庭湖湿地沉水植物大面积消亡.深入研究洞庭湖低水位对沉水植物的生长影响,对指导沉水植物恢复有重要意义.以我国典型通江湖泊洞庭湖典型沉水植物为研究对象,模拟野外沉水植物主要分布区域浅水洼地水文环境,设置4个水位梯度(25、50、75、100 cm),探讨竹叶眼子菜(Potamogeton malaianus)、黑藻(Hydrilla verticillata)、苦草(Vallisneria natans)和金鱼藻(Ceratophyllum demersum)的生长、生物量和生理活性对水位变化的响应.结果显示:(1)前期底质养分含量为:总氮0.09%、总磷0.09%、总钾3.04%、碱解氮20.87 mg/kg、速效磷10.7 mg/kg、速效钾326.67 mg/kg、硝态氮6.97 mg/kg、氨氮6.59 mg/kg、有机碳1.21%、有机质2.09%,2个月后,不同水位的底质养分含量有差异,100和75 cm水池的养分含量高于50和25 cm,氨氮、有机质和有机碳含量在25 cm水位的水池较高;(2)75 cm水位适合竹叶眼子菜和黑藻生长,100 cm水位适合苦草和金鱼藻生长;(3)100 cm水位有利于竹叶眼子菜的繁殖及生物量积累,75 cm水位有利于黑藻和金鱼藻的繁殖及生物量积累,50 cm水位有利于苦草的繁殖及生物量积累;(4)100 cm水位下的沉水植物酶活性强,75和50 cm水位下的沉水植物次之,25 cm水位下的最弱.以上结果表明,4种沉水植物的生长特征和生物量积累随水位变化,在水域生态恢复中应考虑将水位控制在50~100 cm之间,这样有利于促进种群生物量和水生生态系统的恢复. 相似文献
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鄱阳湖典型洲滩湿地土壤含水量和地下水位年内变化特征 总被引：3，自引：0，他引：3
湿地植被空间分布受多个水分因子共同影响,为了探求鄱阳湖典型洲滩湿地不同植被类型下地下水、土壤水的变化特征,本文选择鄱阳湖吴城湿地保护区内一个长约1.2 km的典型洲滩湿地为实验区,建立了气象-土壤-水文联合观测系统.对观测的气象、水文要素进行分析发现:(1)洲滩湿地地下水位年内呈单峰变化,季节性差异显著,最大埋深可达10 m,出现在1月份,丰水期8月份地下水位最高时可出露地表,且地下水位与湖泊水位变化具有高度一致性;(2)由远湖区高地至近湖区低地,不同植被带中地下水平均埋深变化为藜蒿带(4.76 m)芦苇带(2.87 m)灰化薹草带(1.61 m).地下水埋深小于50 cm的持续时间分别为:藜蒿带27 d、芦苇带112 d、灰化薹草带170 d;(3)土壤平均含水量沿不同植被带梯度变化为:藜蒿带最小(15.9%),芦苇样带(40.7%)和灰化薹草样带(43.7%)较大.土壤含水量年内变幅为:藜蒿带最大(2.5%~55.2%),芦苇带和灰化薹草带相对较小,分别为22.1%~48.1%和28.4%~54.1%;(4)不同植被带土壤含水量季节变化规律不同,藜蒿带土壤含水量年内呈单峰型,仅夏季土壤含水量较高,其余季节均在10%左右,而芦苇带和灰化薹草样带春、夏、秋季均维持较高含水量(42%以上),仅冬季水分含量较低. 相似文献
8.
城市河道黑臭底泥对挺水植物光合荧光特性的影响 总被引：4，自引：1，他引：3
城市河道黑臭现象日益严重,探讨常见湿地植物在黑臭底泥中的生长,有利于为河道修复物种选择提供科学依据.研究黑臭底泥对3种常见湿地植物——菖蒲(Acorus calamus)、美人蕉(Canna indica)及慈姑(Sagittaria sagittifolia)生长状况和叶片叶绿素荧光参数的影响.结果表明:菖蒲和美人蕉在第30~40 d时生物量增量明显降低,慈姑的生物量增量在整个实验中持续增加;通过比较3种湿地植物的荧光参数可知,菖蒲和美人蕉的光化学淬灭系数(q P)、相对光合电子传递速率(r ETR)值在第10 d时达到最大,分别为41.33μmol/(m2·s)和68.60μmol/(m2·s),后30 d一直下降;慈姑q P、r ETR值在第30 d时增加;在第40 d时,美人蕉q P值下降,非光化学淬灭系数(q N)值上升,叶片有较强的热耗散能力,而菖蒲的q P、q N值同时下降,黑臭底泥对菖蒲叶片的光合系统PSⅡ造成伤害.这说明黑臭底泥对菖蒲和美人蕉的光合能力产生较长期抑制,而慈姑可较快适应黑臭底泥的胁迫.因此利用湿地植物修复黑臭河道时,可优先选择慈姑,其次是美人蕉,最后是菖蒲. 相似文献
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设计并完成了野外大比例(1:2)土-箱形基础-框架结构相互作用系统顶部小幅激振试验.通过改变上部结构质量和基础侧限埋深,激振试验得到了同一基础不同上部结构质量与同一上部结构不同基础侧限埋深等5种工况下相互作用对系统自振频率及箱形基础阻抗函数的影响.由试验结果分析可知,当上部结构质量增加时,上部结构与土体间的相对刚度降低,相互作用对系统自振频率的影响减弱;同时由于上部结构和基础间惯性相互作用的影响,基础阻抗函数随上部结构质量的增加而增加.随着基础侧限埋深的减小,基础刚度降低,相互作用体现得更加明显.与理论结果相比,无侧限埋深基础的平动和转动基础阻抗值和理论值吻合较好.由于基础侧边回填土剪切模量小于基础底部土体剪切模量,所以同理论值相比试验得到的基础侧限埋深对基础阻抗影响系数相对较小. 相似文献
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Water uptake by saltcedar (Tamarix ramosissima) in a desert riparian forest: responses to intra‐annual water table fluctuation 
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下载免费PDF全文 There is considerable interest in naturalizing flow regime on managed rivers to slow the spread of saltcedar (Tamarix ramosissima) invasion in southwestern USA or to preserve riparian forests dominated by saltcedar and other species in northwestern China. However, little is known about the responses of established saltcedar in water sources to frequent intra‐annual fluctuation of water table resulting from this new, more dynamic flow regime. This study investigates how saltcedar at a riparian site in the middle reaches of the Heihe River, northwest China, responds in water sources use to intra‐annual water table fluctuations. Stable oxygen isotope was employed to determine accurate depth at which saltcedar obtains its water supply, and soil moisture monitoring was used to determine sources of plant‐available soil water. We found that the primary zone of water uptake by saltcedar were stable at 25–60 cm depth, but the water sources used by saltcedar switched between groundwater and soil moisture with the water table fluctuations. Saltcedar derived its water from groundwater when water table was at depth less than 60 cm but switched to soil moisture at 25–60 cm depth when water table declined. It is supposed that the well‐developed clay layer at 60–80 cm depth constrained lateral roots of saltcedar to the soil layers above 60 cm, while the fine‐textured soils at this site, which were periodically resaturated by rising groundwater before the stored soil moisture had become depleted, provided an important water reservoir for saltcedar when groundwater dropped below the primary zone of fine roots. The root distribution of saltcedar may also be related to local groundwater history. The quick decline in water table in the early 1980s when the riparian saltcedar had established may strand its roots in the shallow unsaturated zone. We suggested that raising the water table periodically instead of maintaining it invariably above the rooting depth could sustain desired facultative phreatophytes while maximizing water deliveries. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
12.
Haley A. Schneider W. Andrew Jackson Ken Rainwater Danny Reible Stephen Morse Paul B. Hatzinger Uriel Garza-Rubalcava 《Ground water》2019,57(6):915-924
The fate and transport of groundwater contaminants depends partially on groundwater velocity, which can vary appreciably in highly stratified aquifers. A high-resolution passive profiler (HRPP) was developed to evaluate groundwater velocity, contaminant concentrations, and microbial community structure at ∼20 cm vertical depth resolution in shallow heterogeneous aquifers. The objective of this study was to use mass transfer of bromide (Br−), a conservative tracer released from cells in the HRPP, to estimate interstitial velocity. Laboratory experiments were conducted to empirically relate velocity and the mass transfer coefficient of Br− based on the relative loss of Br− from HRPP cells. Laboratory-scale HRPPs were deployed in flow boxes containing saturated soils with differing porosities, and the mass transfer coefficient of Br− was measured at multiple interstitial velocities (0 to 100 cm/day). A two-dimensional (2D) quasi-steady-state model was used to relate velocity to mass transfer of Br− for a range of soil porosities (0.2–0.5). The laboratory data indicate that the mass transfer coefficient of Br−, which was directly—but non-linearly—related to velocity, can be determined with a single 3-week deployment of the HRPP. The mass transfer coefficient was relatively unaffected by sampler orientation, length of deployment time, or porosity. The model closely simulated the experimental results. The data suggest that the HRPP will be applicable for estimating groundwater velocity ranging from 1 to 100 cm/day in the field at a minimum depth resolution of 10 cm, depending on sampler design. 相似文献
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The objectives of this study are (1) to understand the subsurface hydrology in the Aurku area, Chiayi County, southern Taiwan, and (2) to determine the interaction between the manmade lake and groundwater level through the recharge produced by infiltration by on‐site investigation and laboratory sand tank simulation. The manmade lake was selected as the field site for groundwater recharge effect so as to assess the role of infiltration from the aquaculture ponds in this area. These results can be used as reference for future application of constructing a series of manmade lakes. The field experiment was performed to measure the infiltration rate of the manmade lake by using the water balance method and double‐ring infiltration test. The results demonstrated that the manmade lake had helped the recharge of the groundwater. Raising or maintaining a higher water level of the manmade lake can promote higher infiltration. When the groundwater level is equal to or higher than the bottom of the manmade lake, infiltration will slow or cease. The field experiment and laboratory sand tank simulation demonstrated that the infiltration rate increased with the higher storage depth of the manmade lake. The laboratory simulation also indicated that while the groundwater level was lower than the bottom of manmade lake (i.e. the reference level) and the initial water depth (3 cm) was equal to or greater than 50% of the full water storage depth, the infiltration depth increased with time. However, the infiltration depth would be very small or nearly zero when the groundwater level was higher than the bottom of the manmade lake. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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In the shallow groundwater areas of the North China Plain (NCP), precipitation infiltration and evapotranspiration in the vertical direction are the main processes of the water cycle, in which the unsaturated zone plays an important role in the transformation process between precipitation and groundwater. In this paper, two typical sites in Cangzhou (CZ) and Hengshui (HS) of Hebei province with shallow water tables were selected to analyse the relationship among precipitation, soil water and groundwater. At each site, precipitation, soil water at depths 10, 20, 30, 50, 70, 100, 150, 200, 300 cm, and groundwater were sampled to analyse the stable isotope compositions of hydrogen and oxygen. The soil water potentials at the corresponding depths were observed. Although the climates at the two sites are similar, there are some differences in the infiltration process, soil water movement and groundwater recharge sources. Evaporation occurred at the upper depths, which led to the decrease of soil potential and the enrichment of heavy isotopes. At the CZ site, precipitation infiltrated with piston mode, and an obvious mixture effect existed during the infiltration process. Preferential flow may exist in the soil above 100 cm depth. However, at the HS site soil water moved in piston mode, and groundwater was mainly recharged by precipitation. When precipitation recharged the groundwater it experienced a strong evaporation effect. The results of the soil water movement mechanism provides the transformation relationship among precipitation, soil water and groundwater in the middle and eastern NCP. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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The suprapermafrost groundwater in permafrost region not only is an important component of the water cycle and land surface process, but also is closely associated with the charges of ecological environment in cold region. However, the seasonal dynamics, driving factors, and mechanism of suprapermafrost groundwater are not well understood. Based on observation at slope scale on suprapermafrost groundwater dynamics of typical alpine meadows in the Qinghai-Tibet Plateau, the seasonal dynamics, spatial distribution and driving factors of suprapermafrost groundwater were analyzed. The results showed that there were close relationships between the seasonal dynamics of suprapermafrost groundwater and the freezing-thawing processes of active soil in permafrost region. The seasonal dynamics of suprapermafrost groundwater and its slope distribution pattern were controlled by soil temperature of active layers. The phase and range of the suprapermafrost groundwater dynamics are determined by deep soil(below 60 cm depth) moisture and groundwater recharging sources. The relationship between active soil temperatures and dynamics of suprapermafrost groundwater levels was better described by Boltzmann functions. However, the influencing thresholds of soil temperature on groundwater dynamics varied at different depths of active layers and in different slope positions, which resulted in the significant spatial heterogeneity of suprapermafrost groundwater dynamics in slope scale. Land cover change and global warming certainly altered the dynamics of suprapermafrost groundwater and the hydraulic interaction between groundwater and rivers, and consequently altered the overall hydrologic cycle of watershed scale. 相似文献
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Stream and bed temperature variability in a coastal headwater catchment: influences of surface‐subsurface interactions and partial‐retention forest harvesting 下载免费PDF全文
下载免费PDF全文 Stream temperature was recorded between 2002 and 2005 at four sites in a coastal headwater catchment in British Columbia, Canada. Shallow groundwater temperatures, along with bed temperature profiles at depths of 1 to 30 cm, were recorded at 10‐min intervals in two hydrologically distinct reaches beginning in 2003 or 2004, depending on the site. The lower reach had smaller discharge contributions via lateral inflow from the hillslopes and fewer areas with upwelling (UW) and/or neutral flow across the stream bed compared to the middle reach. Bed temperatures were greater than those of shallow groundwater during summer, with higher temperatures in areas of downwelling (DW) flow compared to areas of neutral and UW flow. A paired‐catchment analysis revealed that partial‐retention forest harvesting in autumn 2004 resulted in higher daily maximum stream and bed temperatures but smaller changes in daily minima. Changes in daily maximum stream temperature, averaged over July and August of the post‐harvest year, ranged from 1.6 to 3 °C at different locations within the cut block. Post‐harvest changes in bed temperature in the lower reach were smaller than the changes in stream temperature, greater at sites with DW flow, and decreased with depth at both UW and DW sites, dropping to about 1 °C at a depth of 30 cm. In the middle reach, changes in daily maximum bed temperature, averaged over July and August, were generally about 1 °C and did not vary significantly with depth. The pre‐harvest regression models for shallow groundwater were not suitable for applying the paired‐catchment analysis to estimate the effects of harvesting. However, shallow groundwater was warmer at the lower reach following harvesting, despite generally cooler weather compared to the pre‐harvest year. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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J. Crowther 《地球表面变化过程与地形》1984,9(5):397-407
CO2 concentrations at depths of 15,30, and 50 cm were determined over a one-year period in six karst soils in the Malay peninsula. Evidence suggests that the highest single CO2 value (MAXCO2, per cent) recorded at each site/depth provides the best estimate of conditions during groundwater recharge events. Soil depth (cm) and bulk density (BDEN) are the best predictors of MAXCO2, with the equation loglo(MAXCO2) = 1·146 (BDEN) + 0·00698 (DEPTH) - 1·227 accounting for 86 per cent of the variation. This equation is used to model MAXCO2 at seven, more remote sites. Soil throughflow patterns and groundwater recharge points are estimated from slope pantometer and soil depth surveys in order to assess the CO2 concentration with which soil waters ultimately equilibrate before entering the limestone. Limestone weathering seems to be predominantly of the open system type, the overall mean MAXCO2 of 1·65 per cent corresponding with a weathering potential of 167 ppm CaCO3. Weathering potentials vary markedly, ranging from 62–82 ppm on rocky hilltops to more than 280 ppm on certain tower karst footslopes in Selangor and the Kinta Valley and on moderate hillslopes developed in impure limestones in the Boundary Range. 相似文献
18.
In the central part of the Bolivian Altiplano, the shallow groundwater presents electrical conductivities ranging from 0·1 to 20 mS/cm. In order to study the origin of this salinity pattern, a good knowledge is required of the geometry of the aquifer at depth. In this study, geophysics has been used to complement the sparse data available from drill holes. One hundred time‐domain electromagnetic (TDEM) soundings were carried out over an area of 1750 km2. About 20 geological logs were available close to some of the TDEM soundings. Three intermediate results were obtained from the combined data: (i) the relationship between the electrical conductivity of the groundwater and the formation resistivity, (ii) geoelectrical cross‐sections and (iii) geoelectrical maps at various depths. The limited data set shows a relationship between resistivity and the nature of the rock. From the cross‐sections, a conductive substratum with a resistivity of less than 1 Ω·m was identified at most of the sites at depths ranging from 50 to 350 m. This substratum could be a clay‐rich formation containing brines. Using derived relationships, maps of the nature of the formation (sandy, intermediate and clayey sediments) were established at depths of 10 and 50 m. Discrimination between sand and clays was impossible where groundwater conductivity is high (>3 mS/cm). In the central part of the area, where the groundwater conductivity is low, sandy sediments are likely to be present from the surface to a depth of more than 200 m. Clayey sediments are more likely to be present in the south‐east and probably constitute a hydraulic barrier to groundwater flow. In conclusion, the study demonstrates the efficiency of the TDEM sounding method to map conductive zones. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
19.
In recent years, the Gravity Recovery and Climate Experiment (GRACE) has provided a new tool to study terrestrial water storage variations (TWS) at medium and large spatial scales, providing quantitative measures of TWS change. Linear trends in TWS variations in Turkey were estimated using GRACE observations for the period March 2003 to March 2009. GRACE showed a significant decrease in TWS in the southern part of the central Anatolian region up to a rate of 4 cm/year. The Global Land Data Assimilation System (GLDAS) model also captured this TWS decrease event but with underestimated trend values. The GLDAS model represents only a part of the total TWS variations, the sum of soil moisture (2 m column depth) and snow water equivalent, ignoring groundwater variations. Therefore, GLDAS model derived TWS variations were subtracted from GRACE derived TWS variations to estimate groundwater storage variations. Results revealed that decreasing trends of TWS observed by GRACE in the southern part of central Anatolia were largely explained by the decreasing trends of groundwater variations which were confirmed by the limited available well groundwater level data in the region. 相似文献