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1.
The ability of wetlands to improve the quality of water has long been recognized and has led to the proliferation of wetlands as a means to treat diffuse and point source pollutants from a range of land uses. However, much of the existing research has been undertaken in temperate climates with a paucity of information on the effectiveness of wetlands, particularly natural wetlands, in tropical regions. This paper contributes to addressing this issue by presenting a comprehensive measurement based assessment of the potential for a naturally occurring tropical riverine wetland to improve the quality of the water entering it. We found small net imports and exports of sediment to/from the wetland in individual years, but over the longer term this kind of wetland is neither a sink nor source of sediment. In contrast, phosphorus was continually removed by the wetland with an overall net reduction of 14%. However, it should be noted that there is no ‘permanent’ gaseous loss mechanism for phosphorus, and its removal from the water column is equal to its accumulation in the wetland soil. We found very little removal of nitrogen by this type of wetland from several analyses including: (i) Surface and groundwater fluxes, (ii) Estimation of water column and soil denitrification rates, (iii) Wetland residence times, and (iv) Hydraulic loading. We also found no clear evidence for transformation of nitrogen to more or less bio‐available forms. Hence, while the benefits of using wetlands to improve water quality in controlled environments have been demonstrated in the literature, these benefits may not always be directly translated to unmanaged natural wetland systems when there is strong seasonality in flows and short residence time during the periods of maximum sediment and nutrient load. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
2.
ABSTRACTConstructed wetlands can be used for reducing nonpoint-source pollution and providing ecological services in a watershed. This paper presents a field monitoring study on water quality improvement in constructed wetlands of five cells in series. The wetland system covers 59.9 ha, or 0.08% of the watershed area; it diverts 7.3 million m3 (hm3) water (or 4.3% annual flow) from a degraded river. The results showed that the hydraulic retention times (HRT) of the five cells ranged from 5 to 15 days, 18.4% inflow was lost to seepage and increased evapotranspiration (ET) in the wetlands; the wetlands retained 99.1% total suspended solids (TSS), 60.9% total phosphorus (TP), and 54.4% total nitrogen (TN) from the inflow. Major reductions of TSS and TP were observed in the first two large cells that occupied 57% of the total wetland area. The smaller cells did not show advantages over the bigger ones in pollutant retention as reported in some studies. Although significant water quality benefit can be achieved by the constructed wetlands, the increased water loss may be a concern, particularly in dry regions.
EDITOR Z.W. Kundzewicz; ASSOCIATE EDITOR T. Okruszko 相似文献
3.
《Acta Geochimica》2016,(1)
This study aims to investigate the effects of region and three regional dominated mangrove species(Avicennia marina, Aegiceras corniculatum and Kandelia candel) on the distribution of inorganic nitrogen and phosphorus. Measurement of the inorganic nitrogen and phosphorus and enzymatic activities was carried out in soils covered by three mangrove species in the Quanzhou Bay estuarine wetlands, a typical coastal wetland in China.Species with a higher biomass in upstream and midstream absorb more nitrogen from soils, and the retention of the available phosphorus in the soils of different regions causes the regional variation of phosphorus. In areas dominated by A. marina, nitrate nitrogen is lower while available phosphorus is higher. Meanwhile, nitrate nitrogen and available phosphorus are higher in the soils covered by K. candel.Moreover, all three species affect the elemental and enzymic stoichiometry. The mangrove species influences the diversity of the elemental and enzymic stoichiometric relationship through differential microenvironments, which induce the biodiversity of wetland ecosystems. Thus, this study may facilitate a better understanding of the transformation ability of mangroves to nitrogen and phosphorus and will therefore be beneficial for providing a basis for the ecological restoration of estuarine wetlands. 相似文献
4.
湖泊湿地的水质净化效应——以太湖三山湿地为例 总被引：3，自引：2，他引：1
为了解湖泊湿地的水质净化效果,以太湖三山湿地为研究对象,综合利用遥感、GIS技术、现场水质监测、实验室分析和模型模拟等方法,分析三山湿地对污染物的拦截净化效果,进而探讨湖泊湿地对水体氮、磷污染物的削减渠道及其贡献率.结果表明三山湿地对太湖水体和三山岛生活污水均有明显净化效果.2014年三山湿地的总氮(TN)、总磷(TP)输入通量分别为549.45和19.4 t,通过水草打捞/收割分别去除20.99和4.52 t,湿地水体内TN、TP变化量分别为528.46和14.88 t,这部分营养盐输出途径包括沉积到底泥、降解转化、水体交换等.湿地的TN、TP拦截能力分别为2723.56和102.48 kg/(hm2·a).水生植物收割打捞与底泥疏浚是提高湿地水质净化能力的有效措施.水动力模拟结果显示,三山湿地建成后使附近水域水体流向发生变化,流速减小,对湿地内水质产生多方面的作用. 相似文献
5.
人工湖滨湿地磷素汇-源功能转换及理论解释 总被引：3，自引：0，他引：3
采用水动力弥散和吸附理论建立了表流湿地水-土界面磷通量模型,定义了湿地汇-源转换的临界水体磷浓度值.模型揭示,湿地对磷的截留是水动力弥散和吸附共同作用的结果.在湿地建成运行初期,吸附作用明显,临界浓度值较低,湿地较好地发挥截磷功能.随着湿地的运行,土壤吸附趋于饱和,吸附作用减弱,水动力弥散变为主导因素,临界浓度值增大,使湿地除磷功能减弱,在一定条件下,反而可能释放磷.本文建立的磷通量模型具有明确的物理基础,能解释湿地对磷去除功能退化的机理和汇-源转换条件.应用模型对抚仙湖马料河湿地的观测数据作了初步解释,该湿地运行两年后,临界磷浓度值为0.58 mg/L,湿地除磷功能明显衰退. 相似文献
6.
Wetlands are known for their water filtration (or purification) function. Although different wetland types differ in their filtration capacity, they are usually aggregated together in economic valuation studies. Here, we explicitly separate the valuation of the suspended sediment and phosphorus (P) filtration services of the four major wetland types—bogs, fens, marshes and swamps—found in southern Ontario, Canada. The areal extents of the four wetland types are derived from the Canadian Wetland Inventory (CWI) progress map, while the sediment accretion rate is used as the key variable regulating the suspended sediment and P filtration functions. Based on available literature data, we assess the relationship of the sediment accretion rate to wetland size. Because only weak positive correlations are found, we assign a mean (average) sediment accretion rate to each wetland type. The sediment accretion rates are combined with mean soil P concentrations to estimate Pretention rates by the wetlands. The replacement cost method is then applied to valuate the sediment and P filtration services. The unit values for both sediment and P retention decrease in the order: marshes > bogs ≈ swamps > fens. The total value of sediment plus phosphorus removal by all wetlands in southern Ontario amounts to $4.2 ± 2.9 billion per year, of which about 80% is accounted for by swamps. We further assess the costs of different options to offset the additional P loading generated in a hypothetical scenario whereby all wetlands are converted to agriculture. The results demonstrate that replacing the P filtration function of existing wetlands with conventional land management and water treatment solutions is not cost-effective, hence reinforcing the importance of protecting existing wetlands. 相似文献
7.
《Limnologica》2020
Assessment and monitoring of biodiversity is critical for conservation planning. Considering the cost and time associated to monitoring, selecting proper bio-indicators is important, particularly in countries where financial resources are limited. The objectives of this study were to investigate community congruence of macroinvertebrates and wetland birds in natural wetlands of southwest Ethiopia, exposed to different levels of human disturbance and to identify important environmental variables related to these bio-indicators. Data on macroinvertebrates, birds, physico-chemical water quality, human disturbance and vegetation cover were collected from 54 sampling sites distributed over 12 wetlands during dry and wet season of 2015. Procrustes analysis was used to quantify community congruence between the two assemblages across different disturbance levels. The congruence of macroinvertebrates and wetland dependent birds was higher for low disturbed wetlands (R2 = 0.60) than for moderately disturbed wetlands (R2 = 0.31). Moderately disturbed wetlands showed no significant congruence between macroinvertebrates and wetland birds and between wetland dependent and wetland associated birds. A significant and positive relation between richness of macroinvertebrates and wetland dependent birds was observed when the full data set was used, whereas no significant relation was observed when the data was split according to the different levels of human disturbance. Vegetation cover, dissolved oxygen, water depth, total nitrogen, total phosphorus and conductivity were significantly correlated with both macroinvertebrate and wetland bird occurrence. Based on our study we suggest to monitor both bio-indicators as they provide important complementary information on the status of the wetlands. 相似文献
8.
The internal riverine processes acting upon phosphorus and dissolved silicon were investigated along a 55 km stretch of the River Swale during four monitoring campaigns. Samples of river water were taken at 3 h intervals at sites on the main river and the three major tributaries. Samples were analysed for soluble reactive phosphorus, total dissolved phosphorus, total phosphorus, dissolved silicon and suspended solid concentration. Mass‐balances for each determinand were calculated by comparing the total load entering the river with the total load measured at the downstream site. The difference, i.e. the residual load, showed that there was a large retention of phosphorus and silicon within the system during the March 1998 flood event, but the other three campaigns produced net‐exports. Cumulative residual loads were calculated for each determinand at 6 h intervals throughout each campaign. This incremental approach showed that the mass‐balance residuals followed relatively consistent patterns under various river discharges. During stable low‐flow, there was a retention of particulate phosphorus within the system and also a retention of total dissolved phosphorus and soluble reactive phosphorus, most likely caused by the sorption of soluble phosphorus by bed‐sediments. In times of high river‐discharge, there was a mobilization and export of stored bed‐sediment phosphorus. During overbank flooding, there was a large retention (58% of total input) of particulate phosphorus within the system, due to the mass deposition of phosphorus‐rich sediment onto the floodplain. Soluble phosphorus was also retained within the system by sequestration from the water column by the high concentration of suspended solids. The dissolved silicon mass‐balance residuals had a less consistent pattern in relation to river discharge. There was a large retention of dissolved silicon during overbank flooding, possibly due to sorption onto floodplain soil, and net‐exports during periods of both stable low‐flow and rising limbs of hydrographs, due to release of dissolved silicon from pore‐waters. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
9.
鄱阳湖湿地土壤微生物活性对年际水文变化的响应 总被引：1，自引：0，他引：1
湿地自然水文节律的改变影响着湿地生态系统的稳定与安全.为探究湿地水文变化对土壤微生物活性的影响,以鄱阳湖洲滩湿地3种典型植被狗牙根（Cynodon dactylon）、南荻（Triarrhena lutarioriparia）和苔草（Carex cinerascens）下表层土壤（0~20 cm）为研究对象,对湿地土壤微生物呼吸、微生物生物量和水解酶等土壤活性特征进行连续3年的实验监测,分析年际水位变化对不同植被湿地土壤微生物活性的影响.结果表明：丰水年显著提高土壤中养分的可利用性（有机质、总磷、速效磷）,提高土壤微生物生物量、微生物熵、水解酶活性,表明丰水年有利于湿地生态系统的物质循环转化.水文条件也能通过影响湿地植被生长改变土壤养分状况,进而对植被下土壤微生物活性产生显著影响.诸多土壤理化因子中,可溶性有机碳是驱动微生物活性变化最关键的因子.进一步分析表明,由植被类型所代表的长期水文累积效应对湿地土壤理化及微生物活性的调节作用大于单纯的年际水文变化. 相似文献
10.
Distinct export dynamics for dissolved and particulate phosphorus reveal independent transport mechanisms in an arable headwater catchment 
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下载免费PDF全文 Rémi Dupas Chantal Gascuel‐Odoux Nicolas Gilliet Catherine Grimaldi Gérard Gruau 《水文研究》2015,29(14):3162-3178
This paper investigates particulate phosphorus (PP) and soluble reactive phosphorus (SRP) concentrations at the outlet of a small (5 km²) intensively farmed catchment to identify seasonal variability of sources and transport pathways for these two phosphorus forms. The shape and direction of discharge‐concentration hystereses during floods were related to the hydrological conditions in the catchment during four hydrological periods. Both during flood events and on an annual basis, contrasting export dynamics highlighted a strong decoupling between SRP and PP export. During most flood events, discharge‐concentration hystereses for PP were clockwise, indicating mobilization of a source located within or near the stream channel. Seasonal variability of PP export was linked to the availability of stream sediments and the export capacity of the stream. In contrast, hysteresis shapes for SRP were anticlockwise, which suggests that SRP was transferred to the stream via subsurface flow. Groundwater rise in wetland soils was likely the cause of this transfer, through the hydrological connectivity it created between the stream and P‐rich soil horizons. SRP concentrations were the highest when the relative contribution of deep groundwater from the upland domain was low compared with wetland groundwater. Hence, soils from non‐fertilized riparian wetlands seemed to be the main source of SRP in the catchment. This conceptual model of P transfer with distinct hydrological controls for PP and SRP was valid throughout the year, except during spring storm events, during which PP and SRP exports were synchronized as a consequence of overland flow and erosion on hillslopes. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
11.
Wetlands in the coastal catchments adjacent to the Great Barrier Reef lagoon play an important role in local hydrological processes and provide important ecological habitats for terrestrial and aquatic species. Although many wetlands have been removed or degraded by agricultural expansion, there is now great interest in their protection and restoration as important aquatic ecosystems and potential filters of pollutant runoff. However, the filtering capacity of tropical wetlands is largely unknown, so the current study was established to quantify the water, sediment and nutrient balance of a natural riverine wetland in tropical north Queensland. Surface and groundwater fluxes of water, sediment and nutrients into and out of the wetland were monitored for a 3‐year period. This paper focuses on the water balance of this natural wetland and a companion paper presents its sediment and nutrient balance and estimates of water quality filtering. Wetland inflows and outflows were dominated by surface flows which varied by 3–4 orders of magnitude through the course of the year, with 90% of the annual flow occurring during the period January to March. Although groundwater inputs to the wetland were only 5% of the annual water balance, they are very important to sustaining the wetland during the dry season, when they can be the largest input of water (up to 90%). Water retention times in this type of wetland are very short, particularly when most of the flow and any associated materials are passing through it (i.e. 1–2 h), so there is little time to filter most of the annual flux of water through this wetland. Longer retention times occur at the end of the dry season (up to 8·5 days); but this is when the lowest fluxes of water pass through the wetland. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
12.
The Okavango wetland in northern Botswana is one of the world's largest inland deltas. The delta is a dynamic environment with shifting channel routes, causing growth and decay of ?anking wetlands, and giving birth to islands. Primary island nuclei are formed by ?uvial processes and bioengineering, and subsequently grow into secondary larger islands of irregular shape by clastic and chemical sedimentation, and later by coalescence. This article presents classi?cations and quantitative estimations of channels, wetlands and islands of the Okavango Delta. Islands were classi?ed dependent on composition, pattern of composition, shape and juxtaposition. 90 per cent of all islands in the entire wetland were identi?ed, with a classi?cation accuracy of 60 to 85 per cent. Smaller islands of the nucleus types dominate the upper parts of the delta, whereas larger secondary islands are more common in the distal part, a re?ection of the age of the islands. Islands in the entry valley of the delta, the Panhandle, are larger in the top end – the primary region of recent clastic sedimentation. The overall size distribution of islands in the delta, however, shows no clumps, indicating that island growth is a uniform process over time and space. The total area ?ooded at least every decade is approximately 14 000 km2, of which 9000 km2 is classi?ed as actual wetland. Channel meandering decreases from the Panhandle to the distal part of the delta, with the abandoned Thaoge channel as an exception. Occurrence of ?uvially formed islands in the distal delta indicates that the water ?ow and area of inundation must once have been much larger. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
13.
火烧作为调控因子,对植物群落结构和生态系统功能具有重要影响,但在湖泊湿地中研究较少.通过野外调查取样与实验室分析,探讨火烧对洞庭湖湿地主要群落类型——荻(Miscanthus sacchariflorus)和苔草(Carex brevicuspis)土壤化学性质的影响.结果表明:火烧后,苔草群落土壤硝态氮含量显著减少64.6%,有机质含量增加26.3%;而荻群落土壤与之相反,硝态氮含量增加186.9%,有机质含量减少22.9%.火烧后,苔草群落的全氮、铵态氮、全碳和全磷含量均显著增加,分别增加了75.4%、36.3%、102.7%和76.9%,而荻群落土壤与对照组间无显著差异.总体上,火烧对荻群落土壤养分影响不大,可作为芦苇场的一种管理方式,但火烧促进苔草群落土壤养分释放,有助于苔草群落提前萌芽和生长,并引起牲畜牧食增加. 相似文献
14.
Sanghcul Lee Gregory W. McCarty Glenn E. Moglen Megan W. Lang Ali M. Sadeghi Timothy R. Green In‐Young Yeo Martin C. Rabenhorst 《水文研究》2019,33(2):305-315
Ecosystem services provided by depressional wetlands on the coastal plain of the Chesapeake Bay watershed (CBW) have been widely recognized and studied. However, wetland–groundwater interactions remain largely unknown in the CBW. The objective of this study was to examine the vertical interactions of depressional wetlands and groundwater with respect to different subsurface soil characteristics. This study examined two depressional wetlands with a low‐permeability and high‐permeability soil layer on the coastal plain of the CBW. The surface water level (SWL) and groundwater level (GWL) were monitored over 1 year from a well and piezometer at each site, respectively, and those data were used to examine the impacts of subsurface soil characteristics on wetland–groundwater interactions. A large difference between the SWL and GWL was observed at the wetland with a low‐permeability soil layer, although there was strong similarity between the SWL and GWL at the wetland with a high‐permeability soil layer. Our observations also identified a strong vertical hydraulic gradient between the SWL and GWL at the wetland with a high‐permeability soil layer relative to one with a low‐permeability soil layer. The hydroperiod (i.e., the total time of surface water inundation or saturation) of the wetland with a low‐permeability soil layer appeared to rely on groundwater less than the wetland with a high‐permeability soil layer. The findings showed that vertical wetland–groundwater interactions varied with subsurface soil characteristics on the coastal plain of the CBW. Therefore, subsurface soil characteristics should be carefully considered to anticipate the hydrologic behavior of wetlands in this region. 相似文献
15.
Nobuo Ishiyama Takumi Akasaka Futoshi Nakamura 《Aquatic Sciences - Research Across Boundaries》2014,76(3):437-449
Management of wetland connectivity is important for biodiversity conservation. In the modern agricultural landscape, the natural connections between floodplain wetlands have been greatly altered. Agricultural ditches and channelized streams are widely distributed in floodplains, which may contribute to the maintenance of wetland connectivity and biodiversity. To determine how these watercourse networks affect wetland biodiversity, we examined the relationship between the species richness of aquatic animals and wetland connectivity, with a special focus on species mobility. From July to August 2011, fish and aquatic insects were collected from 24 wetlands in northern Japan. To determine the degree of wetland connectivity, we assessed the relative importance of individual wetlands in maintaining the entire wetland network using two connectivity indices: hydrologic connectivity via watercourses and spatial connectivity defined as Euclidian distances between wetlands using graph theory. We found that only high mobility groups of both taxa could enhance species richness in either a hydrologic (fish) or spatial (insect) wetland network. The species richness of insects with high-flying ability was found to increase as spatial connectivity increased. Furthermore, the species richness of fish with high-swimming ability was positively influenced by hydrologic connectivity, most likely because highly mobile species were able to reach suitable habitats and migrate from source populations in a wetland network owing to their good mobility. Our findings indicate that hydrologic network is important for maintaining biodiversity as well as spatial connectivity. It is important to focus conservation efforts on key wetlands with high hydrologic and spatial connectivity in future wetland management. 相似文献
16.
Dissolved organic matter variations in coastal plain wetland watersheds: The integrated role of hydrological connectivity,land use,and seasonality 下载免费PDF全文
下载免费PDF全文 Dissolved organic matter (DOM) is integral to fluvial biogeochemical functions, and wetlands are broadly recognized as substantial sources of aromatic DOM to fluvial networks. Yet how land use change alters biogeochemical connectivity of upland wetlands to streams remains unclear. We studied depressional geographically isolated wetlands on the Delmarva Peninsula (USA) that are seasonally connected to downstream perennial waters via temporary channels. Composition and quantity of DOM from 4 forested, 4 agricultural, and 4 restored wetlands were assessed. Twenty perennial streams with watersheds containing wetlands were also sampled for DOM during times when surface connections were present versus absent. Perennial watersheds had varying amounts of forested wetland (0.4–82%) and agricultural (1–89%) cover. DOM was analysed with ultraviolet–visible spectroscopy, fluorescence spectroscopy, dissolved organic carbon (DOC) concentration, and bioassays. Forested wetlands exported more DOM that was more aromatic‐rich compared with agricultural and restored wetlands. DOM from the latter two could not be distinguished suggesting limited recovery of restored wetlands; DOM from both was more protein‐like than forested wetland DOM. Perennial streams with the highest wetland watershed cover had the highest DOC levels during all seasons; however, in fall and winter when temporary streams connect forested wetlands to perennial channels, perennial DOC concentrations peaked, and composition was linked to forested wetlands. In summer, when temporary stream connections were dry, perennial DOC concentrations were the lowest and protein‐like DOM levels the highest. Overall, DOC levels in perennial streams were linked to total wetland land cover, but the timing of peak fluxes of DOM was driven by wetland connectivity to perennial streams. Bioassays showed that DOM linked to wetlands was less available for microbial use than protein‐like DOM linked to agricultural land use. Together, this evidence indicates that geographically isolated wetlands have a significant impact on downstream water quality and ecosystem function mediated by temporary stream surface connections. 相似文献
17.
云南抚仙湖窑泥沟复合湿地的除氮效果 总被引：11，自引：3，他引：8
为了延缓抚仙湖局部湖湾水体富营养化趋势,在北岸建设了净化面积1hm2.的复合人工湿地.综合利用生物氧化塘、水平潜流湿地和表面流湿地治理技术,对入湖河道窑泥沟污水中氮的去除效果进行了试验研究.试验结果表明,湿地系统的除氮效果十分明显,水力负荷年平均为437mm／d,氮负荷年平均为3.315 g／(m2·d),湿地系统氮滞留量年平均为1.91g／(m2·d).其中,通过植物吸收同化作用除氮量为0.142g／(m2·d),占总氮滞留量的7.5％左右.湿地系统对污水中硝酸盐及亚硝酸盐氮(NOX-)、氨氮(NH4+)、有机氮(TON)和总氮(TN)的去除率年平均分别为62.7％、53.8％、62.4％和57.5％.在湿地系统各功能区中,表面流人工湿地除氮效果最佳,氮去除率年平均为39.4％,硝化和反硝化作用均较强;生物净化塘除氮效果次之,氮去除率年平均为18.5％;潜流人工湿地氮去除率年平均为10.6％;沉淀池中氮去除率年平均只有3.6％. 相似文献
18.
Wetland hydroperiod classification in the western prairies using multitemporal synthetic aperture radar 下载免费PDF全文
下载免费PDF全文 Joshua S. Montgomery Chris Hopkinson Brian Brisco Shane Patterson Stewart B. Rood 《水文研究》2018,32(10):1476-1490
Wetlands represent one of the world's most biodiverse and threatened ecosystem types and were diminished globally by about two‐thirds in the 20th century. There is continuing decline in wetland quantity and function due to infilling and other human activities. In addition, with climate change, warmer temperatures and changes in precipitation and evapotranspiration are reducing wetland surface and groundwater supplies, further altering wetland hydrology and vegetation. There is a need to automate inventory and monitoring of wetlands, and as a study system, we investigated the Shepard Slough wetlands complex, which includes numerous wetlands in urban, suburban, and agricultural zones in the prairie pothole region of southern Alberta, Canada. Here, wetlands are generally confined to depressions in the undulating terrain, challenging wetlands inventory and monitoring. This study applied threshold and frequency analysis routines for high‐resolution, single‐polarization (HH) RADARSAT‐2, synthetic aperture radar mapping. This enabled a growing season surface water extent hyroperiod‐based wetland classification, which can support water and wetland resource monitoring. This 3‐year study demonstrated synthetic aperture radar‐derived multitemporal open‐water masks provided an effective index of wetland permanence class, with overall accuracies of 89% to 95% compared with optical validation data, and RMSE between 0.2 and 0.7 m between model and field validation data. This allowed for characterizing the distribution and dynamics of 4 marsh wetlands hydroperiod classes, temporary, seasonal, semipermanent, and permanent, and mapping of the sequential vegetation bands that included emergent, obligate wetland, facultative wetland, and upland plant communities. Hydroperiod variation and surface water extent were found to be influenced by short‐term rainfall events in both wet and dry years. Seasonal hydroperiods in wetlands were particularly variable if there was a decrease in the temporary or semipermanent hydroperiod classes. In years with extreme rain events, the temporary wetlands especially increased relative to longer lasting wetlands (84% in 2015 with significant rainfall events, compared with 42% otherwise). 相似文献
19.
潜流湿地中微生物对三峡库区微污染水净化效果的影响 总被引：2，自引：1，他引：1
为了探讨潜流湿地对三峡库区微污染河水的净化效果,在野外构建芦竹、菖蒲、空心菜和无植物(空白)水平潜流人工湿地,研究人工湿地系统中微生物基本菌群和功能菌群数量分布,探讨污染物去除与微生物菌群种类和数量的相关性.结果表明:实验湿地系统运行情况良好,植物湿地系统对各污染物指标的去除效果优于空白湿地系统;芦竹、菖蒲、空心菜和空白湿地系统的微生物数量均随温度的降低而减少,其中,植物湿地系统的微生物数量高于空白系统;各湿地系统的微生物数量与水质指标去除率之间的相关性较强,在夏季,不同人工湿地系统的细菌总数与CODMn的去除率之间存在着显著的正相关,真菌、亚硝酸细菌总数与铵氮去除率之间均存在着显著的正相关,在冬季,不同人工湿地系统的反硝化细菌总数与总氮去除率之间存在着显著的正相关. 相似文献
20.
In situ measurements of wind‐driven salt fluxes through constructed channels in a coastal wetland ecosystem 下载免费PDF全文
下载免费PDF全文 A suite of instruments was deployed in a coastal wetland ecosystem in the Albemarle estuarine system, North Carolina (USA), to characterize wind‐driven transport of saltwater through a constructed (man‐made) channel. Flow velocity, electrical conductivity, and stage were measured in a representative channel over a 2‐month period from May to July 2014, during which 4 wind tides were observed. Collected data show that thousands of metric tons of salt were advected through the channel into coastal wetlands during each event, which lasted up to 4 days. The results reveal that as much as 36% of advected salts accumulated in the wetlands, suggesting that the cumulative effects of these events on the health of coastal wetlands in the Albemarle system may be substantial due to the abundance of constructed channels and the frequency of wind‐driven tidal events. This study is the first to quantify wind‐driven salt fluxes through constructed channels in coastal wetland settings. 相似文献