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1.
The bioindication role of macropytes in the assessment of the environmental conditions of small water bodies under the conditions of a megalopolis is discussed. A comparative characteristic is given to the significance of macrophytes from different ecological groups, including hygrophytes (cattail, reed), hydrophyte (pondweed), and hydatophytes (Canada water weed, hornweed), growing in small water bodies in St. Petersburg, for the biogeochemical indication of environmental pollution by microelements (Fe, Mn, Zn, Cu, Cr, Ni, Pb, and Cd) and biogenic elements (K, Ca, Na, P, S). Possible mechanisms of detoxication of heavy metal ions in macrophyte organisms and their role in the stable functioning of water bodies in urban territory under the conditions of anthropogenic pollution are discussed. The prospects of the use of macrophyte groups for the bioindication of pollution and phytoremediation of aquatic ecosystems are analyzed. 相似文献
2.
Steven M. Wondzell 《水文研究》2011,25(22):3525-3532
Many hyporheic papers state that the hyporheic zone is a critical component of stream ecosystems, and many of these papers focus on the biogeochemical effects of the hyporheic zone on stream solute loads. However, efforts to show such relationships have proven elusive, prompting several questions: Are the effects of the hyporheic zone on stream ecosystems so highly variable in place and time (or among streams) that a consistent relationship should not be expected? Or, is the hyporheic zone less important in stream ecosystems than is commonly expected? These questions were examined using data from existing groundwater modelling studies of hyporheic exchange flow at five sites in a fifth‐order, mountainous stream network. The size of exchange flows, relative to stream discharge (QHEF:Q), was large only in very small streams at low discharge (area ≈ 100 ha; Q < 10 l/s). At higher flows (flow exceedance probability > 0·7) and in all larger streams, QHEF:Q was small. These data show that biogeochemical processes in the hyporheic zone of small streams can substantially influence the stream's solute load, but these processes become hydrologically constrained at high discharge or in larger streams and rivers. The hyporheic zone may influence stream ecosystems in many ways, however, not just through biogeochemical processes that alter stream solute loads. For example, the hyporheic zone represents a unique habitat for some organisms, with patterns and amounts of upwelling and downwelling water determining the underlying physiochemical environment of the hyporheic zone. Similarly, hyporheic exchange creates distinct patches of downwelling and upwelling. Upwelling environments are of special interest, because upwelling water has the potential to be thermally or chemically distinct from stream water. Consequently, micro‐environmental patches created by hyporheic exchange flows are likely to be important to biological and ecosystem processes, even if their impact on stream solute loads is small. Published in 2011 by John Wiley & Sons, Ltd. 相似文献
3.
From a molecular level to an ecosystem scale, different coupling mechanisms take place during coupled carbonnitrogen-water(C-N-H_2O) cycle, of which essential are water flux and related biogeochemical processes through physicochemical reactions associated with terrestrial and aquatic ecosystems. Meanwhile, regional coupled C-N-H_2O cycle will subsequently impact regional gross primary productivity(GPP) and C and N exchanges during air-water interactions that occur downstream of watersheds. This study aimed to first synthetically analyze the regional dynamics of C, N and H_2O cycles in ecosystems and determine their interactional relationships; second, to specify regional C-N-H_2O coupled relationships of ecosystems and their theoretical ecological principles; third, to classify coupled regional response and adaptation of the C-N-H_2O cycle to climatic and environmental changes under anthropogenic activities, providing a theoretical basis to fully understand and make adjustments to interactional C, N and H_2O cycling relationships at different ecosystem scales and under associated coupling processes. 相似文献
4.
Shucheng Xie 《中国科学:地球科学(英文版)》2018,61(10):1379-1383
Global warming, the most severe faunal mass extinction and the shift of biogeochemical cycles were observed in the ocean across the Permian-Triassic boundary about 252 million years ago, providing an analog to understanding the modern oceans. Along with the progressive global warming, the biogeochemical cycle was documented to show a shift from the decoupled processes of carbon, nitrogen and sulfur prior to the mass extinction to the coupled biogeochemical processes during faunal mass extinction. The coupled biogeochemical cycle was further observed to shift from the coupled C-N processes during the first episode of the faunal mass extinction to the coupled C-N-S processes during the second episode, diagnostic of the progressive development of more deteriorated marine environmental conditions and the more severe biotic crisis across the Permian-Triassic boundary. The biogeochemical cycles could thus be an indication to the progressive collapse of marine ecosystems triggered by the global warming in Earth history. In modern oceans, the coupled C-N cycle triggered by the global warming was observed in some regions. If these local C-N processes develop and expand to the global oceans, the coupled C-N-S processes might be brought into existence and the marine ecosystems are inevitable to suffer from complete collapse as observed at 252 million years ago. 相似文献
5.
湖沼学是研究内陆水体的多学科整合科学——兼论我国湖沼学发展面临的挑战与机遇 总被引：1，自引：0，他引：1
湖沼学是研究内陆水体的多学科交叉综合性科学,自从Forel F.A.于1892年首次对湖沼学做出定义以来已有近130年历史.湖沼学的主要分支学科包括地质湖沼学(包括古湖沼学)、物理湖沼学、化学(生物地球化学)湖沼学和生物湖沼学.湖沼学的关键自然属性是通过跨学科的整合,从水生态系统水平综合分析相关过程与机理,并对生态系统变化进行预测.因此,湖泊学也是支撑水资源与生态系统保护、管理与修复的核心科学.然而,目前我国湖沼学发展面临分支学科发展不平衡、研究碎片化等问题,而人类活动加剧和气候变化对内陆水体生态系统的影响及管理对策是湖沼学研究面临的挑战与机遇.我国湖沼学研究亟需围绕人类活动、气候变化的影响,重点开展以下几个方面的工作:1)水动力与水文地貌特征变化及其环境生态效应; 2)营养盐和有机质生物地球化学循环及其环境生态效应; 3)食物网结构与功能; 4)外来入侵物种的影响与控制对策; 5)与水环境有关的传染病防治; 6)地表水生态评价; 7)生态系统演变机理与退化生态系统修复等. 相似文献
6.
Sophocleous M 《Ground water》2007,45(4):393-401
Conflicts between ecosystems and human needs for fresh water are increasing. The purpose of this paper is to raise awareness in the hydrogeologic community of environmental flows (EFs) and to address the major challenges involved in their protection. Ground water is a key component of EFs, and therefore hydrogeologists are called upon to get involved in the ongoing debates about maintaining healthy riverine ecosystems. Promising opportunities for achieving EFs in both underallocated and overallocated basins as well as new methods for protecting fresh water ecosystems developed in different countries are outlined. EF protection measures include private water trusts, "upside-down instream flow water rights," the "public trust" doctrine, and water markets, among other measures. A number of knowledge gaps are identified, to which hydrogeologists could contribute, such as our rudimentary knowledge about ground water-dependent ecosystems, aspects of stream-aquifer interactions, and the impacts of land-use changes. The values that society places on the different uses of water ultimately determine where the water is allocated. EF requirements can be legitimately recognized and addressed by basing the environmental needs of hydrologic systems on robust science, focusing on increasing the productivity of water use, engaging society in understanding the benefits and costs of decisions that affect ecosystems, and taking advantage of various opportunities for achieving EF goals. 相似文献
7.
《Acta Geochimica》2017,(4)
Rivers link terrestrial ecosystems and marine ecosystems, and they transport large amounts of substances into oceans each year, including several forms of silicon(Si), carbon(C), and other nutrients. However, river damming affects the water flow and biogeochemical cycles of Si, C, and other nutrients through biogeochemical interacting processes. In this review, we first summarize the current understanding of the effects of river damming on the processes of biogeochemical Si cycle, especially the source, composition, and recycling process of biogenic silica(BSi). Then, we introduce dam impacts on the cycles of C and some other nutrients. Dissolved silicon in rivers is mainly released from phytolith dissolution and silicate weathering. BSi in suspended matter or sediments in most rivers mainly consists of phytoliths and mainly originates from soil erosion. However, diatom growth and deposition in many reservoirs formed by river interception may significantly increase the contribution of diatom Si to total BSi, and thus significantly influence the biogeochemical Si,C, and nutrient cycles. Yet the turnover of phytoliths and diatoms in different rivers formed by river damming is still poorly quantified. Thus, they should be further investigated to enhance our understanding about the effects of river damming on global biogeochemical Si, C and nutrient cycles. 相似文献
8.
Chlorinated persistent organic pollutants, including polychlorinated biphenyls(PCBs), represent a particularly serious environmental problem and human health risk worldwide. Leguminous plants and their symbiotic bacteria(rhizobia) are important components of the biogeochemical cycling of nitrogen in both agricultural and natural ecosystems. However, there have been relatively few detailed studies of the remediation of PCB-contaminated soils by legume-rhizobia symbionts. Here we report for the first time evidence of the reductive dechlorination of 2,4,4′-trichlorobiphenyl(PCB 28) by an alfalfa-rhizobium nitrogen fixing symbiont. Alfalfa(Medicago sativa L.) inoculated with wild-type Sinorhizobium meliloti had significantly larger biomass and PCB 28 accumulation than alfalfa inoculated with the nitrogenase negative mutant rhizobium Sm Y. Dechlorination products of PCB 28, 2,4′-dichlorobiphenyl(PCB 8), and the emission of chloride ion(Cl-) were also found to decrease significantly in the ineffective nodules infected by the mutant strain Sm Y. We therefore hypothesize that N2-fixation by the legume-rhizobium symbiont is coupled with the reductive dechlorination of PCBs within the nodules. The combination of these two processes is of great importance to the biogeochemical cycling and bioremediation of organochlorine pollutants in terrestrial ecosystems. 相似文献
9.
磷是地表水体中的关键性营养盐,在水生生态系统的物质循环与能量流动方面发挥着重要作用,研究水体中磷的来源、转化与归趋对于了解水环境的演变过程与科学保护具有重要意义.近年来,磷酸盐氧同位素(δ18 O P)技术已逐渐应用于淡水环境中磷的来源示踪与生物地球化学循环研究,其样品前处理主要沿用海水方法体系.相比而言,淡水样品中PO 3-4浓度通常较低,有机质和干扰离子含量却较高,复杂的样品前处理过程极大地制约了δ18 O P分析在淡水环境体系的广泛应用.为此,本研究针对现有海水样品δ18 O P前处理方法在地表淡水环境的适用性加以检验,并进行了三点优化改进:①将MAGIC沉淀步骤使用的MgCl 2替换为Mg(NO 3)2,避免了Cl-的干扰,减少AgCl杂质的生成;②调节生成Ag3PO4溶液pH值为8.0,保证Ag3PO4沉淀快速完全;③对Ag3PO4沉淀过程采用避光处理,降低了AgNO 3及Ag3PO4可能的光解影响,提高了Ag3PO4的纯度,使δ18 O P的测试结果更为准确.本改进方法为后续利用δ18 O P技术深入探究淡水环境中磷的生物地球化学循环与生态环境效应提供了有益的方法借鉴. 相似文献
10.
溶解氧（DO）对湖库的生物地球化学循环、生态系统结构和功能起着至关重要的作用,也是评价水生态系统的敏感性指标.DO浓度的降低对水生态有着重要影响.结果显示,多数湖库在夏秋季热分层期间,由于温跃层较高的密度梯度、藻类衰亡和有机质的降解以及微生物的呼吸作用会消耗大量的DO,从而形成温跃层溶解氧最小值（MOM）,甚至在该区域诱发厌氧状态.MOM可驱动浮游动物日夜垂向迁移,影响无脊椎动物和鱼类分布迁移模式及种群结构,破坏水体生态分布,致使生物非正常死亡,危害水体生态安全;此外,MOM也可诱发温跃层温室气体（CH4和CO2）大量形成,影响水源地水质,成为湖库生态安全隐患.目前对MOM所导致的生态风险和水质问题以及最终的控制方法已有较多研究成果,但缺乏综述性的研究.本文从MOM研究历史、研究方法、形成原因、生态风险及控制方法等方面进行论述,并展望今后研究热点,旨在推进MOM的相关研究进展,保障湖库生态平衡和供水水质安全. 相似文献
11.
William H. McDowell Miguel C. Leon Michelle D. Shattuck Jody D. Potter Tamara Heartsill-Scalley Grizelle González James B. Shanley Adam S. Wymore 《水文研究》2021,35(4):e14146
Catchments in the Luquillo Experimental Forest (LEF) of Puerto Rico are warm, wet and tropical with steep elevational relief creating gradients in temperature and rainfall. Long-term objectives of research at the site are to understand how changing climate and disturbance regimes alter hydrological and biogeochemical processes in the montane tropics and to provide information critical for managing and conserving tropical forest ecosystems globally. Measurements of hydrology and meteorology span decades, and currently include temperature, humidity, precipitation, cloud base level, throughfall, groundwater table elevation and stream discharge. The chemistry of rain, throughfall, and streams is measured weekly and lysimeters and wells are sampled monthly to quarterly. Multiple data sets document the effects of major hurricanes including Hugo (1989), Georges (1998) and Maria (2017) on vegetation, biota and catchment biogeochemistry and provide some of the longest available records of biogeochemical fluxes in tropical forests. Here we present an overview of the findings and the data sets that have been generated from the LEF, highlighting their importance for understanding montane tropical watersheds in the context of disturbance and global environmental change. 相似文献
12.
Marlène Jobard Serena Rasconi Télesphore Sime-Ngando 《Aquatic Sciences - Research Across Boundaries》2010,72(3):255-268
Fungi are a highly complex group of organisms of the kingdom Eumycota (i.e. the true-fungi) and other fungus-like organisms
traditionally studied by mycologists, such as slime molds (Myxomycota) and oomycota (Straminopiles or Heterokonts). They constitute
a significant proportion of the as yet undiscovered biota that is crucial in ecological processes and human well-being, through
at least three main trophic modes: saprophytism, parasitism, or symbiosis. In addition to direct benefit (sources of antibiotics)
or adverse effects (agents of disease), fungi can impact many environmental processes, particularly those associated with
the decomposition of organic matter. They are present in almost all regions and climates, even under extreme conditions. However,
studies have focussed mostly on economically interesting species, and knowledge of their diversity and functions is mainly
restricted to soil, rhizosphere, mangrove, and lotic ecosystems. In this study, we review the diversity and potential functions
of microscopic fungi in aquatic ecosystems, with focus on the pelagic environments where they often are regarded as allochthonous
material, of low ecological significance for food-web processes. Recent environmental 18S rDNA surveys of microbial eukaryotes
have (1) unveiled a large reservoir of unexpected fungal diversity in pelagic systems, (2) emphasized their ecological potentials
for ecosystem functioning, and (3) opened new perspectives in the context of food-web dynamics. In spite of persisting methodological
difficulties, we conclude that a better documentation of the diversity and quantitative and functional importance of fungi
will improve our understanding of pelagic processes and biogeochemical cycling. 相似文献
13.
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15.
Shane C. Lishawa KathiJo Jankowski Pamela Geddes Daniel J. Larkin Andrew M. Monks Nancy C. Tuchman 《Aquatic Sciences - Research Across Boundaries》2014,76(4):483-495
Wetland ecosystems maintain and improve water quality through the process of denitrification, an increasingly important ecosystem service due to global N pollution. Invasive plants have the potential to disrupt denitrification by altering the environmental conditions that facilitate this process. Great Lakes coastal wetlands are experiencing widespread invasion by highly productive hybrid cattail with largely uncertain biogeochemical effects. Through field and controlled mesocosm studies, we sought to determine the effects of cattail invasion through time on denitrification rates and associated environmental factors in a Great Lakes coastal wetland. In the field, we found that cattail density correlated with increased denitrification and a suite of environmental and plant community characteristics and denitrification rates were positively correlated with NH4 +, sediment organic matter, reduced water levels, and cattail stand age. Through our controlled mesocosm study, we documented conditions 1- and 5-year following invasion and found that denitrification rates and soil organic matter increased in year 5, and cattail and year-since-invasion altered plant communities and soil NH4 +. Only a weak correlation between denitrification rates and cattail treatments was noted, however, owing to high replicate variability. Our results indicate that with increasing cattail residence time, one ecosystem service, biodiversity, was negatively impacted, while two other services, denitrification and sediment carbon accumulation, were enhanced. Thus, this highly invaded wetland still provides valuable services to aquatic ecosystems and to society. A holistic perspective is therefore critical when evaluating invasive species impacts in which negative impacts are weighed against other ecosystem services, which may be stimulated. 相似文献
16.
The Shenandoah Watershed Study (established in 1979) and the Virginia Trout Stream Sensitivity Study (established in 1987) serve to increase understanding of hydrological and biogeochemical changes in western Virginia mountain streams that occur in response to acidic deposition and other ecosystem stressors. The SWAS-VTSSS program has evolved over its 40+ year history to consist of a temporally robust and spatially stratified monitoring framework. Currently stream water is sampled for water quality bi-hourly during high-flow events at three sites and weekly at four sites within Shenandoah National Park (SHEN), and quarterly at 72 sites and on an approximately decadal frequency at ~450 sites within the wider western Virginia Appalachian region. Stream water is evaluated for pH, acid neutralizing capacity (ANC), base cations (calcium, magnesium, sodium and potassium ion), acid anions (sulphate, nitrate and chloride), silica, ammonium, and conductivity with a subset of samples evaluated for monomeric aluminium and dissolved organic carbon. Hourly stream discharge (four sites) and in-situ measurements of conductivity, water and air temperature (three sites) are also measured within SHEN. Here we provide an overview and timeline of the SWAS-VTSSS stream water monitoring program, summarize the field and laboratory methods, describe the water chemistry and hydrologic data sets, and document major watershed disturbances that have occurred during the program history. Website links and instructions are provided to access the stream chemistry and time-series monitoring data in open-access federal databases. The purpose of this publication is to promote awareness of these unique, long-term data sets for wider use in catchment studies. The water chemistry and hydrologic data can be used to investigate a wide range of biogeochemical research questions and provide key inputs for models of these headwater stream ecosystems. SWAS-VTSSS is an ongoing program and quality assured data sets are uploaded to the databases annually. 相似文献
17.
Evaluation and application of dialysis porewater samplers for microbiological studies at sediment-water interfaces 总被引：1，自引：1，他引：1
The equilibrium diffusion technique has become a valuable tool for ecological and biogeochemical studies in aquatic environments. In sediment ecosystems, changes in concentration of microbial metabolites with increasing depth can be determined dependably and reproducibly with this technique. Since the permeation characteristics of the membranes employed are crucial, selecting the proper membrane requires knowledge about its behavior under conditions which prevail in the natural environment. Thirteen polymer sheets were evaluated comparing permeation terms for biogeochemically relevant solutes, biodegradability, and mechanical strength. Cellulose-based dialysis membranes are most satisfactory when employed in low temperature anoxic environments. For this membrane, correction terms were calculated to account for diffusion losses during retrieval and sampling. Optimal incubation times can now be predicted from experimentally determined permeation coefficients for several porewater solutes. Dialysis porewater samplers (DPS) have been successfully applied during more than 100 independent experiments for the collection of interstitial water from surface sediments. DPS were used for water depths as deep as 290 meters. 相似文献
18.
D. von Schiller V. Acuña D. Graeber E. Martí M. Ribot S. Sabater X. Timoner K. Tockner 《Aquatic Sciences - Research Across Boundaries》2011,73(4):485-497
Temporary streams are a dominant surface water type in the Mediterranean region. As a consequence of their hydrologic regime,
these ecosystems contract and fragment as they dry, and expand after rewetting. Global change leads to a rapid increase in
the extent of temporary streams, and more and more permanent streams are turning temporary. Consequently, there is an urgent
need to better understand the effects of flow intermittency on the biogeochemistry and ecology of stream ecosystems. Our aim
was to investigate how stream nutrient availability varied in relation to ecosystem contraction, fragmentation and expansion
due to hydrologic drying and rewetting. We quantified the temporal and spatial changes in dissolved nitrogen (N) and phosphorus
(P) concentrations along a reach of a temporary Mediterranean forest stream during an entire contraction–fragmentation–expansion
hydrologic cycle. We observed marked temporal changes in N and P concentrations, in the proportion of organic and inorganic
forms as well as in stoichiometric ratios, reflecting shifts in the relative importance of in-stream nutrient processing and
external nutrient sources. In addition, the spatial heterogeneity of N and P concentrations and their ratios increased substantially
with ecosystem fragmentation, reflecting the high relevance of in-stream processes when advective transport was lost. Overall,
changes were more pronounced for N than for P. This study emphasizes the significance of flow intermittency in regulating
stream nutrient availability and its implications for temporary stream management. Moreover, our results point to potential
biogeochemical responses of these ecosystems in more temperate regions under future water scarcity scenarios. 相似文献
19.
J. W. N. Smith M. Bonell J. Gibert W. H. McDowell E. A. Sudicky J. V. Turner R. C. Harris 《水文研究》2008,22(1):151-157
A summary is provided of the second in a series of Integrated Science Initiative workshops supported by the UNESCO International Hydrological Programme. The workshop brought together hydrologists, ecologists, biogeochemists, hydrogeologists and natural resource managers to discuss the processes that occur in hyporheic and riparian ecotones. The principal objectives were to share new ideas on the importance of biogeochemical processes that affect nutrients at the groundwater–surface water interface, to understand the impact of nutrient flux on stream (principally hyporheic) ecology, and to identify the management strategies for river corridors to mitigate the effects of nutrients applied to land and discharged via groundwater into rivers. The workshop concluded that: (1) more interdisciplinary research and environmental management practices are needed to better understand, predict and manage processes at the interface of environmental compartments; (2) the goal of environmental regulations to improve ecological health requires a holistic approach integrating our understanding of the ecological, hydrological, biogeochemical and physical processes; (3) upscaling spatially and temporally variable processes remains difficult and may hinder translation of research at micro‐scales (molecular to grain size) into macro‐scale (reach to catchment) decision‐making; (4) scientists need to better communicate existing research to river managers, while smanagers must better communicate policy and regulatory‐driven science requirements to researchers. Existing models, such as those that simulate stream–hyporheic exchange, are not widely known and rarely used by environmental managers. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
20.
Distributions of fatty acids in a stalagmite related to paleoclimate change at Qingjiang in Hubei,southern China 总被引：5，自引：0，他引：5
XIE Shucheng HUANG Junhua WANG Hongmei YI Yi HU Chaoyong CAI Yanjun & CHENG Hai . Faculty of Earth Science China University of Geosciences Wuhan China . School of Environmental Studies China University of Geosciences Wuhan China . SKLLQG Institute of Earth Environment Chinese Academy of Sciences Xi’an China . Department of Geology Geophysics University of Minnesota MN USA 《中国科学D辑(英文版)》2005,48(9):1463-1469
~~Distributions of fatty acids in a stalagmite related to paleoclimate change at Qingjiang in Hubei,southern China1. Dorale, J. A., Edward, R. L., Ito, E. et al., Climate and vegetation history of mid-continent from 75 to 25 ka: A speleothem record from Crevice Cave, Missouri, USA, Science, 1998, 282(5395): 1871-1874.
2. Li, B., Yuan, D., Qin, J. et al., Oxygen and carbon isotopic char- acteristics of rainwater, drip water and present speleofhems in a cave in Guilin area, and thei… 相似文献