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1.
Renato Gerdol Lisa Brancaleoni Lorenzo Lastrucci Giovanni Nobili Mauro Pellizzari Michele Ravaglioli Daniele Viciani 《Estuaries and Coasts》2018,41(7):2079-2091
Wetlands are important centers of biodiversity. Coastal wetlands are subject to anthropogenic threats that can lead to biodiversity loss and consequent negative effects on nature conservation. We investigated relationships between wetland vegetation and habitat conditions in a coastal Nature Reserve in Northern Italy that has undergone seawater intrusion and eutrophication for several decades. The wetland vegetation in the Nature Reserve consisted of nine communities of hygrophytic and helophytic vegetation and five communities of waterplant vegetation. The hygrophytic and helophytic communities were arranged according to a salinity gradient, from salt-free habitats to strongly saline habitats. The saline habitats had high nutrient levels, due to the influx of nitrate-rich saltwater from an adjacent lagoon. The waterplant communities were all typical of freshwater habitats. Water-table depth and concentration of dissolved nutrients in the water were the main factors structuring waterplant vegetation. The main driver of future changes in the wetland vegetation of the Nature Reserve is the ongoing increase in salinity levels which may enhance expansion of halophilic species and communities, thus outcompeting locally rare freshwater species. If nutrient, especially nitrate, load further increases in the next future, this may exert negative effects on wetland species and communities preferring nutrient-poor habitats. 相似文献
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鄱阳湖水质污染对湿地生态系统生态功能的影响 总被引：6，自引：0，他引：6
湿她内部生物、物理、化学组份之间的相互作用过程,推动湿地的形成和发育,是其生态结构和生态功能的物质基础。水是鄱阳湖湖泊及其湿地的主体要素之一,各种形式的水是参与湿地生态过程的主体成分．贯穿融于生态形成和系统运作的生物、物理、化学过程的每一个环节,湖泊水质的变化直接影响着湿地的生态过程,影响水域生态系统、湖滩草洲生态系统、农牧与生态系统食物链和食物网的质量．所以水质变化及污染是湿地生态功能衰退研究的核心内容之一。 相似文献
4.
Analyses of hydrochemistry, modes of occurrence and dynamic dispersion of brine discharges were used to assess the economic potentials, environmental and geotechnical problems of saline water discharges in the Abakaliki Basin. Total salt concentration, energy input requirement and the nature of containment structures are important considerations in selection of appropriate and sustainable sourcing and processing system. Solute dispersion patterns from the brine discharges are controlled by the semi-regional hydrodynamic regime that is defined by the shallow, unconfined, fractured aquifer system. The ionic solute invasion from brines not only contribute to marginal wetland degradation, ground and surface water contamination but also predicate low performance and failures in water abstraction and supply systems through encrustation and corrosion. Brine harvest for industrial and domestic applications appears to be a major remedy to inhibit the environmental and geotechnical impacts of the brine discharges. 相似文献
5.
Upstream inflow decline and excessive water withdrawal are the major reasons for failure in maintaining ecological functions of wetlands and could lead to wetland drought and degradation. Quantitative evaluation of wetlands drought constitutes the basis for managing and scheduling water resources and guaranteeing biological safety. In the study, we proposed a Palmer wetland drought index (PWDI) based on the water balance model that describes wetland hydrological characteristics linked to its located basin to describe drought-reflected ecological characteristics in lacustrine Baiyangdian Wetland and compared it with Palmer drought severity index (PDSI). The results presented that PWDI is able to reflect the worst drought in history, and the drought is mainly affected by water stored in the wetland, but PDSI is inadequate for evaluating the wetland drought. The PWDI methodology provides a clear, objective approach for describing the intensity of drought and can be readily adapted to characterize drought on an operational basis. 相似文献
6.
耦合湿地模块的流域水文模型是开展流域湿地变化的水文效应及其水文功能评估的有效工具,其模拟效率直接关系到模拟精度和应用价值。选取中国湿地主要分布区之一的嫩江流域,利用PHYSITEL/HYDROTEL模型平台,构建孤立湿地和河滨湿地模块并与流域水文模型耦合,并从拟合优度指数和模拟效率角度评价了耦合湿地模块的流域水文模型模拟效率。结果表明,耦合湿地模块的流域水文模型,拟合和验证期间模型的拟合度指数均有所提高,嫩江富拉尔基和大赉水文站控制流域的Nash-Sutcliffe系数和克林效率系数平均提高了3.08%和4.64%,均方根误差和相对偏差平均降低了12.72%和55.93%,且整个研究时段模拟结果的流量指数总体更接近于观测的径流数据。可见,耦合湿地模块的流域水文模型可提高水文过程模拟精度,更好地定量评估湿地水文功能,为流域水资源精准调控与湿地修复保护提供重要支撑。 相似文献
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Tidal freshwater marshes around the world face an uncertain future with increasing water levels, salinity intrusion, and temperature and precipitation shifts associated with climate change. Due to the characteristic abundance of both annual and perennial species in these habitats, even small increases in early growing season water levels may reduce seed germination, seedling establishment, and late-season plant cover, decreasing overall species abundance and productivity. This study looks at the distribution of tidal freshwater marsh plant species at Jug Bay, Patuxent River (Chesapeake Bay, USA), with respect to intertidal elevation, and the relationship between inundation early in the growing season and peak plant cover to better understand the potential impacts and marsh responses to increased inundation. Results show that 62% of marsh plant species are distributed at elevations around mean high water and are characterized by narrow elevation ranges in contrast with species growing at lower elevations. In addition, the frequency and duration of inundation and water depth to which the marsh was exposed to, prior to the growing season (March 15–May 15), negatively affected peak plant cover (measured in end-June to mid-July) after a threshold value was reached. For example, 36 and 55% decreases in peak plant cover were observed after duration of inundation threshold values of 25 and 36% was reached for annual and perennial species, respectively. Overall, this study suggests that plant communities of tidal freshwater marshes are sensitive to even small systematic changes in inundation, which may affect species abundance and richness as well as overall wetland resiliency to climate change. 相似文献
8.
John W. Day Robert R. Christian Donald M. Boesch Alejandro Yáñez-Arancibia James Morris Robert R. Twilley Larissa Naylor Linda Schaffner Court Stevenson 《Estuaries and Coasts》2008,31(3):477-491
Climate impacts on coastal and estuarine systems take many forms and are dependent on the local conditions, including those
set by humans. We use a biocomplexity framework to provide a perspective of the consequences of climate change for coastal
wetland ecogeomorphology. We concentrate on three dimensions of climate change affects on ecogeomorphology: sea level rise,
changes in storm frequency and intensity, and changes in freshwater, sediment, and nutrient inputs. While sea level rise,
storms, sedimentation, and changing freshwater input can directly impact coastal and estuarine wetlands, biological processes
can modify these physical impacts. Geomorphological changes to coastal and estuarine ecosystems can induce complex outcomes
for the biota that are not themselves intuitively obvious because they are mediated by networks of biological interactions.
Human impacts on wetlands occur at all scales. At the global scale, humans are altering climate at rapid rates compared to
the historical and recent geological record. Climate change can disrupt ecological systems if it occurs at characteristic
time scales shorter than ecological system response and causes alterations in ecological function that foster changes in structure
or alter functional interactions. Many coastal wetlands can adjust to predicted climate change, but human impacts, in combination
with climate change, will significantly affect coastal wetland ecosystems. Management for climate change must strike a balance
between that which allows pulsing of materials and energy to the ecosystems and promotes ecosystem goods and services, while
protecting human structures and activities. Science-based management depends on a multi-scale understanding of these biocomplex
wetland systems. Causation is often associated with multiple factors, considerable variability, feedbacks, and interferences.
The impacts of climate change can be detected through monitoring and assessment of historical or geological records. Attribution
can be inferred through these in conjunction with experimentation and modeling. A significant challenge to allow wise management
of coastal wetlands is to develop observing systems that act at appropriate scales to detect global climate change and its
effects in the context of the various local and smaller scale effects. 相似文献
9.
Impact of peatland drainage and restoration on esker groundwater resources: modeling future scenarios for management 总被引：1，自引：0，他引：1
Esker aquifers are common groundwater bodies in Europe. Management of these aquifers should take account of the sustainability of groundwater-dependent ecosystems and land use in an integrated way. An unconfined esker aquifer in northern Finland was modelled with MODFLOW to determine how groundwater resources are impacted by the surrounding peatland drainage scheme and to simulate scenarios for possible drainage restoration. The impacts of groundwater abstraction and climate change were also simulated. A calibration-constrained Monte Carlo method was used to provide information on the uncertainties associated with model predictions. The results suggest that peatland drainage in the vicinity of eskers can have a significant role in lowering the water table, even though climate variability may mask these impacts. Drainage restoration by filling the ditches might have positive impacts on the aquifer water levels. Comparison of water-table changes caused by peatland drainage with the changes brought by water abstraction and climate variability helped to quantify impacts of different land-use scenarios and facilitated discussion with the local stakeholders. Based on this study, more attention should be devoted to peatland drainage schemes in integrated groundwater management of esker aquifers. 相似文献
10.
Reshmi Sarkar 《Environmental Earth Sciences》2018,77(14):530
Increasing CO2 levels and its consequent effects have been prominent with climate change. Three out of ten transgressed planetary boundaries reflect our planet’s status at tipping point. Soil Organic Carbon (SOC) which helps soil supply water and nutrients to plants through roots is inherently related to various ecological systems and needs urgent attention. Although the total SOC globally is more than the total carbon in biosphere and atmosphere, the vulnerability of SOC due to anthropogenic activities is unavoidable. The environmental factors affecting sequestration of SOC, soil fertility, crop production, accelerated SOC removal with rising temperatures, green-house gases emissions and climate change are interrelated. Thus, it is impossible to understand and estimate the various scenarios of impacts on SOC pool with ever-changing ecosystems and related processes in soil environment completely. Based on currently predicted climate change scenarios, if deforestation is controlled and reestablishment is achieved, tropical forests can trap atmospheric CO2 in the cheapest way and function as the largest sink on earth. The agricultural management practices (AMPs), which have been practiced in the last two decades and found helpful are suitable. However, some innovative adaptations such as crop modelling, selecting types of residue to change microbial communities, practices of grassland-grazing and low-C-emission AMPs are also necessary. To achieve the millennium development goals, we must accomplish food security, which relates all 17 sustainable development goals (SDGs) also relays agricultural systems, soil systems, ecosystem services, soil fertility and how best we nurture SOC pool with supportive AMPs. 相似文献
11.
Nekton communities were sampled from 38 Hawaiian coastal wetlands from 2007 to 2009 using lift nets, seines, and throw nets
in an attempt to increase our understanding of the nekton assemblages that utilize these poorly studied ecosystems. Nekton
were dominated by exotic species, primarily poeciliids (Gambusia affinis, Poecilia spp.) and tilapia. These fish were present in 50–85% of wetlands sampled; densities were up to 15 times greater than native
species. High densities of exotic fish were generally found in isolated wetlands with no connection to the ocean, were often
the only nekton present, were positively correlated with surface water total dissolved nitrogen, and were negatively correlated
with native species richness. Native species were present in wetlands with complete or partial connection to the ocean. Additional
studies are needed to document exotic fish impacts on native fish and bird habitat and whether native fish communities can
contribute to invasion resistance of coastal wetlands. Future wetland restoration should include exotic fish eradication,
maintenance of hydrological connection to the ocean, or programs to prevent future introductions in order to create wetlands
that support native-dominated nekton communities. 相似文献
12.
Considering groundwater use to improve the assessment of groundwater pumping for irrigation in North Africa 总被引：1，自引：0，他引：1
Sylvain Massuel Farida Amichi Fatah Ameur Roger Calvez Zakia Jenhaoui Sami Bouarfa Marcel Kuper Hamadi Habaieb Tarik Hartani Ali Hammani 《Hydrogeology Journal》2017,25(6):1565-1577
Groundwater resources in semi-arid areas and especially in the Mediterranean face a growing demand for irrigated agriculture and, to a lesser extent, for domestic uses. Consequently, groundwater reserves are affected and water-table drops are widely observed. This leads to strong constraints on groundwater access for farmers, while managers worry about the future evolution of the water resources. A common problem for building proper groundwater management plans is the difficulty in assessing individual groundwater withdrawals at regional scale. Predicting future trends of these groundwater withdrawals is even more challenging. The basic question is how to assess the water budget variables and their evolution when they are deeply linked to human activities, themselves driven by countless factors (access to natural resources, public policies, market, etc.). This study provides some possible answers by focusing on the assessment of groundwater withdrawals for irrigated agriculture at three sites in North Africa (Morocco, Tunisia and Algeria). Efforts were made to understand the different features that influence irrigation practices, and an adaptive user-oriented methodology was used to monitor groundwater withdrawals. For each site, different key factors affecting the regional groundwater abstraction and its past evolution were identified by involving farmers’ knowledge. Factors such as farmer access to land and groundwater or development of public infrastructures (electrical distribution network) are crucial to decode the results of well inventories and assess the regional groundwater abstraction and its future trend. This leads one to look with caution at the number of wells cited in the literature, which could be oversimplified. 相似文献
13.
John D. Skalbeck Donald M. Reed Randall J. Hunt Jamie D. Lambert 《Hydrogeology Journal》2009,17(1):215-228
Historically, drier types of wetlands have been difficult to characterize and are not well researched. Nonetheless, they are considered to reflect the precipitation history with little, if any, regard for possible relation to groundwater. Two seasonal coastal wetland types (wet prairie, sedge meadow) were investigated during three growing seasons at three sites in the Lake Michigan Basin, Wisconsin, USA. The six seasonal wetlands were characterized using standard soil and vegetation techniques and groundwater measurements from the shallow and deep systems. They all met wetland hydrology criteria (e.g., water within 30 cm of land surface for 5% of the growing season) during the early portion of the growing season despite the lack of appreciable regional groundwater discharge into the wetland root zones. Although root-zone duration analyses did not fit a lognormal distribution previously noted in groundwater-dominated wetlands, they were able to discriminate between the plant communities and showed that wet prairie communities had shorter durations of continuous soil saturation than sedge meadow communities. These results demonstrate that the relative rates of groundwater outflows can be important for wetland hydrology and resulting wetland type. Thus, regional stresses to the shallow groundwater system such as pumping or low Great Lake levels can be expected to affect even drier wetland types. 相似文献
14.
Identifying flow processes in multi-aquifer flow systems is a considerable challenge, especially if substantial abstraction occurs. The Rajshahi Barind groundwater flow system in Bangladesh provides an example of the manner in which flow processes can change with time. At some locations there has been a decrease with time in groundwater heads and also in the magnitude of the seasonal fluctuations. This report describes the important stages in a detailed field and modelling study at a specific location in this groundwater flow system. To understand more about the changing conditions, piezometers were constructed in 2015 at different depths but the same location; water levels in these piezometers indicate the formation of an additional water table. Conceptual models are described which show how conditions have changed between the years 2000 and 2015. Following the formation of the additional water table, the aquifer system is conceptualised as two units. A pumping test is described with data collected during both the pumping and recovery phases. Pumping test data for the Lower Unit are analysed using a computational model with estimates of the aquifer parameters; the model also provided estimates of the quantity of water moving from the ground surface, through the Upper Unit, to provide an input to the Lower Unit. The reasons for the substantial changes in the groundwater heads are identified; monitoring of the recently formed additional water table provides a means of testing whether over-abstraction is occurring. 相似文献
15.
Pore water geochemistry near the sediment-water interface of a zoned, freshwater wetland in the southeastern United States 总被引：6，自引：0，他引：6
Sediment and its associated pore water were collected from a zoned, freshwater, riparian wetland, located in the Talladega
National Forest, northeastern Hale County, Alabama, to study the porewater chemistry and its spatial changes within and between
the wetland ecological zones. Obvious changes in pH, Eh and element concentrations were observed between the different wetland
ecological zones. Major cations (Ca, Mg, and Na) and trace elements (B, Ba, Sr, and Mn) have very good spatial correlation
with Fe and Mn distributions, both in the pore water and the sediment, suggesting that adsorption on, and desorption from,
iron and manganese oxyhydroxides are important processes controlling the distributions of these elements in the wetland sediment.
However, an equilibrium adsorption model is not able to explain the distribution of trace elements between the pore water
and sediment. A redox kinetic model gives similar vertical profiles for iron and the correlated elements as those measured
in the field and thus suggests that the relative rates of ferrous iron oxidation and the reductive dissolution of ferric iron
in the sediment are important variables determining the distributions of these elements in the wetland pore waters.
Received: 31 October 1996 · Accepted: 27 May 1997 相似文献
16.
Tidal freshwater wetlands (TFW) are situated in the upper estuary in a zone bordered upstream by the nontidal river and downstream by the oligohaline region. Here, discharge of freshwater from the river and the daily tidal pulse from the sea combine to create conditions where TFW develop. TFW are often located where human population density is high, which has led to wetland degradation or destruction. Globally, TFW are largely restricted to the temperate zone where the magnitude of annual river discharge prevents saline waters from penetrating too far inland. The constant input of river water delivers high loads of sediments, dissolved nutrients, and other suspended matter leading to high sedimentation rates and high nutrient levels. Prominent biogeochemical processes include the transformation of nitrogen by bacteria and immobilization of phosphate. A diverse, characteristic vegetation community develops which supports a rich fauna. Biotic diversity is highest in the high marsh areas and decreases in the lower levels where tidal inundation is greatest. Benthic fauna is rather poor in diversity but high in biomass compared to other regions of the estuary. Global climate change is a threat for this system directly by sea level rise, which will cause brackish water to intrude into the fresh system, and indirectly during droughts, which reduce river discharge. Salinity will affect the presence of flora and fauna and facilitates sulfate reduction of organic matter in the soil. Increased decomposition of organic matter following saltwater intrusion can result in a lowering of wetland surface elevation. The papers assembled in this issue focus on how these tidal freshwater wetlands have changed over recent time and how they may respond to new impacts in the future. 相似文献
17.
João Magalhães Neto Heliana Teixeira Joana Patrício Alexandra Baeta Helena Veríssimo Rute Pinto João Carlos Marques 《Estuaries and Coasts》2010,33(6):1327-1339
Anthropogenic activities are a disturbance factor of coastal systems and can be widely recognized as a major threat to the
health of coastal systems. However, natural events cannot be disregarded from management issues because of their significant
influence on the communities living in these areas. Based on long-term subtidal data from the Mondego Estuary (Portugal),
the effects of natural events (e.g., floods and droughts) on macrobenthic communities were compared with the anthropogenic
events. Sampling stations were grouped into characteristic zones (mouth, north arm, south arm) so the community dynamics of
each of these estuarine areas could be followed over time. Environmental assessment was performed for stations using the Benthic
Assessment Tool (BAT), and compared with the existing pressures. Human impacts persist over a number of years and gradually
reduce ecosystem health, as discussed in the European Water Framework Directive. Paradoxically, natural events cause stronger
impacts but are of a shorter duration, which allows for a faster recovery of macrobenthic communities. The study showed that
caution should be taken when developing and implementing water policies so as not to disregard the importance of the different
events (natural and human-caused) on the ecosystem health (e.g., community degradation and water quality and ecological quality
status assessment). 相似文献
18.
Modelling cumulative impacts of basin-scale coal seam gas (CSG) extraction is challenging due to the long time frames and spatial extent over which impacts occur combined with the need to consider local-scale processes. The computational burden of such models limits the ability to undertake calibration and sensitivity and uncertainty analyses. A framework is presented that integrates recently developed methods and tools to address the computational burdens of an assessment of drawdown impacts associated with rapid CSG development in the Surat Basin, Australia. The null space Monte Carlo method combined with singular value decomposition (SVD)-assisted regularisation was used to analyse the uncertainty of simulated drawdown impacts. The study also describes how the computational burden of assessing local-scale impacts was mitigated by adopting a novel combination of a nested modelling framework which incorporated a model emulator of drawdown in dual-phase flow conditions, and a methodology for representing local faulting. This combination provides a mechanism to support more reliable estimates of regional CSG-related drawdown predictions. The study indicates that uncertainties associated with boundary conditions are reduced significantly when expressing differences between scenarios. The results are analysed and distilled to enable the easy identification of areas where the simulated maximum drawdown impacts could exceed trigger points associated with legislative ‘make good’ requirements; trigger points require that either an adjustment in the development scheme or other measures are implemented to remediate the impact. This report contributes to the currently small body of work that describes modelling and uncertainty analyses of CSG extraction impacts on groundwater. 相似文献
19.
S. Perveen T. Yigitcanlar Md. Kamruzzaman J. Hayes 《International Journal of Environmental Science and Technology》2017,14(3):663-678
Urban growth is an important phenomenon, which is taking place on an unprecedented scale, and its impacts on society and the environment are evident. In theory, an evaluation of such urban growth through scenario-based planning helps planners to better assess the future impacts of growth and develop better policies and plans. Within this context, the assessment of transport impacts is particularly important as transport plays an important role in shaping urban growth. Additionally, transport sector alone is responsible for about one-third of the greenhouse gas emissions of cities, which has detrimental effects on the environment, economy, community health, and quality of life. In practice, however, scarce evidence exists outlining the challenges of scenario-based evaluation and how to best address these while modelling the transport impacts of various urban growth scenarios. This research addresses these gaps in the literature and assesses the effectiveness of scenario-based planning methods that are used for modelling the transport impacts of alternative urban growth scenarios. The methodological approach of the study consists of a critical review of the key literature and relevant methods that are commonly used to assess transport impacts. The results of this analysis highlight limitations of existing methods for effectively evaluating transport externalities of urban growth scenarios. The findings suggest that among many reviewed models, the ILUTE, URBANSIM and TRANUS simulation models are identified as significant ones. However, due to various limitations of the former two, TRANUS is noted as the most suitable one for evaluating the transport impacts of urban growth scenarios. 相似文献
20.
浅埋的地下水位以及泉水溢出是张掖城市湿地形成的主要原因。在充分考虑保持湿地现状的同时,顾及到湿地区内农耕区不至于因地下水位变化而产生负茴环境地质影响。将2005年8月份湿地保护区水位埋深,确定为保持湿地现状的地下水位埋深临界值。按照张掖城市湿地保护区的基本特征、表现、生态保护目标,生态需水量主要包括湿地植被蒸腾量、湿地土壤蒸发量、灌溉需水量以及景观建设需水量等。计算得生态需水量为3053．87×10^4m^3/a。湿地生态需水量的分析与计算对于制定合理的湿地保护措施具有重要意义。 相似文献