共查询到20条相似文献，搜索用时 15 毫秒
1.
Zofia Ecaterina Taranu Dörte Köster Roland I. Hall Theo Charette Francine Forrest Les C. Cwynar Irene Gregory-Eaves 《Aquatic Sciences - Research Across Boundaries》2010,72(1):97-115
Although comparative analyses between dimictic and polymictic lakes have noted the key role of mixing regime in governing
water quality, limnologists have historically focused on dimictic lakes, leaving polymictic lakes relatively understudied.
In this study, we investigated whether the effects of agricultural development on water quality differed between dimictic
and polymictic lakes in a naturally nutrient-rich region of Alberta, Canada. Through a spatial limnological analysis of 36
sites, we found that the relationship between surface water total phosphorus concentration and the percent of agriculture
(% Agr) in the catchments differed between dimictic and polymictic lakes, where the proportion of variance explained was much
more pronounced in the dimictic (79% explained) than in the polymictic systems (7% explained). Paleolimnological analyses
of subfossil chironomids in surface sediment samples (0–1 cm) from 18 of the 36 study lakes, and in sediment core profiles
from the dimictic and polymictic basins of a eutrophic lake, showed that water quality differed between mixis groups. We found
that the surface sediment chironomid assemblages differed significantly between polymictic and dimictic lakes. Detailed analyses
of the sediment cores demonstrated that the two basin types differed in their responses to land-use change through time, as
only the dimictic basin showed a parallel increase in anoxia with increasing agricultural development. We suggest that in
naturally-fertile landscapes, external nutrient loading exerts a more notable effect on dimictic lakes, whereas internal nutrient
loading is more important in polymictic systems. 相似文献
2.
冰川融水通过热量、水、物质传输对山地冰冻圈冰湖水文效应产生影响,引起广泛关注.本文从山地冰冻圈冰湖的水量、物理化学性质、生物等方面系统总结冰川融水对冰湖水文效应的影响.冰川融水被冰湖滞留能在一定程度上延缓区域冰川水资源的亏损,但也直接导致了潜在危险性冰湖数量和危险程度增大.冰川融水对冰湖物理性质的影响主要表现在降低湖水温度、影响透明度/浊度、改变湖水密度、造成湖水热力分层现象等方面,对冰湖化学性质的影响主要表现在增加湖水中的氮素、溶解有机物、持久性有机污染物、各类离子和重金属等,进而影响冰湖生物的分布、组成、结构和功能.深入系统地开展冰川融水及其变化对冰湖水文效应研究,对冰川水文与水资源、山地冰冻圈生态环境研究具有重要意义. 相似文献
3.
R. A. Müller M. N. Futter S. Sobek J. Nisell K. Bishop G. A. Weyhenmeyer 《Aquatic Sciences - Research Across Boundaries》2013,75(4):535-545
The character of organic carbon (OC) in lake waters is strongly dependent on the time water has spent in the landscape as well as in the lake itself due to continuous biogeochemical OC transformation processes. A common view is that upstream lakes might prolong the water retention in the landscape, resulting in an altered OC character downstream. We calculated the number of lakes upstream for 24,742 Swedish lakes in seven river basins spanning from 56º to 68º N. For each of these lakes, we used a lake volume to discharge comparison on a landscape scale to account for upstream water retention by lakes (Tn tot). We found a surprisingly weak relationship between the number of lakes upstream and Tn tot. Accordingly, we found that the coloured fraction of organic carbon was not related to lake landscape position but significantly related to Tn tot when we analysed lake water chemical data from 1,559 lakes in the studied river basins. Thus, we conclude that water renewal along the aquatic continuum by lateral water inputs offsets cumulative retention by lakes. Based on our findings, we suggest integrating Tn tot in studies that address lake landscape position in the boreal zone to better understand variations in the character of organic carbon across lake districts. 相似文献
4.
Lakes are common in glaciated mountain regions and geomorphic principles suggest that lake modifications to water and sediment fluxes should affect downstream channels. Lakes in the Sawtooth Mountains, Idaho, USA, were created during glaciation and we sought to understand how and to what extent glacial morphology and lake disruption of fluxes control stream physical form and functions. First, we described downstream patterns in channel form including analyses of sediment entrainment and hydraulic geometry in one catchment with a lake. To expand on these observations and understand the role of glacial legacy, we collected data from 33 stream reaches throughout the region to compare channel form and functions among catchments with lakes, meadows (filled lakes), and no past or present lakes. Downstream hydraulic geometry relationships were weak for both the single catchment and regionally. Our data show that downstream patterns in sediment size, channel shape, sediment entrainment and channel hydraulic adjustment are explained by locations of sediment sources (hillslopes and tributaries) and sediment sinks (lakes). Stream reaches throughout the region are best differentiated by landscape position relative to lakes and meadows according to channel shape and sediment size, where outlets are wide and shallow with coarse sediment, and inlets are narrow and deep with finer sediment. Meadow outlets and lake outlets show similarities in the coarse‐sediment fraction and channel capacity, but meadow outlets have a smaller fine‐sediment fraction and nearly mobile sediment. Estimates of downstream recovery from lake effects on streams suggest 50 per cent recovery within 2–4 km downstream, but full recovery may not be reached within 20 km downstream. These results suggest that sediment sinks, such as lakes, in addition to sources, such as tributaries, are important local controls on mountain drainage networks. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
5.
April L. James Emily Dusome Tim Field Huaxia Yao Chris McConnell Andy Beaton Arghavan Tafvizi 《水文研究》2020,34(4):914-926
Stable isotope tracers of δ18O and δ2H are increasingly being applied in the study of water cycling in regional-scale watersheds in which human activities, like river regulation, are important influences. In 2015, δ18O and δ2H were integrated into a water quality survey in the Muskoka River Watershed with the aim to provide new regional-scale characterization of isotope hydrology in the 5,100-km2 watershed located on the Canadian Shield in central Ontario, Canada. The forest dominated region includes ~78,000 ha of lakes, 42 water control structures, and 11 generating stations, categorized as “run of river.” Within the watershed, stable isotope tracers have long been integrated into hydrologic process studies of both headwater catchments and lakes. Here, monthly surveys of δ18O and δ2H in river flow were conducted in the watershed between April 2015 and November 2016 (173 surface water samples from 10 river stations). Temporal patterns of stable isotopes in river water reflect seasonal influences of snowmelt and summer-time evaporative fractionation. Spatial patterns, including differences observed during extreme flood levels experienced in the spring of 2016, reflect variation in source contributions to river flow (e.g., snowmelt or groundwater versus evaporatively enriched lake storage), suggesting more local influences (e.g., glacial outwash deposits). Evidence of combined influences of source mixing and evaporative fractionation could, in future, support application of tracer-enabled hydrological modelling, estimation of mean transit times and, as such, contribute to studies of water quality and water resources in the region. 相似文献
6.
The simulation of heat and water exchange in the boreal spruce forest by the land-surface model SWAP 总被引：1，自引：0，他引：1
All previous versions of a physically based land-surface model SWAP have assumed for simplicity that vegetation is fully covered by snow during the cold season. Such assumption is reasonable only for the regions dominated by short vegetation or for warm climates where snow processes are absent. The major goals of this paper are (i) modification of the latest version of SWAP by incorporation of tall vegetation into the cold-season parameterizations to make the model applicable for simulating heat and water transfer within a boreal forest biome and (ii) validation of the modified version using the data from a forested catchment located in the boreal zone. Modification of SWAP required to parameterize radiative and turbulent exchange between the forest crown and forest floor, partitioning snowfall between interception by the canopy (in doing so, snow interception differs from rain interception) and falling to the ground, formation of snow cover on the forest crown and forest floor including snow accumulation (both in solid and liquid fractions), snow evaporation, and snowmelt. The advanced model was validated using a set of hydrometeorological data measured during 18 years (1966–1983) at the Tayozhniy catchment (covered by boreal spruce forest), Valdai, Russia. Simulations of annual and monthly snow/rain interception, daily runoff at the catchment outlet, snow density, snow depth, snow water equivalent, soil water storage in three layers (0–20, 0–50 and 0–100 cm), and monthly evapotranspiration from the catchment were compared with observations. Analysis of the results of validation shows that the new version of the model SWAP reproduces the heat and water exchange processes occurring in mid-latitude boreal forest quite reasonable. 相似文献
7.
Numerical studies of the relationships between littoral processes and environmental variables are important because they provide understanding of the impacts of natural and human factors on lake systems. In this study, littoral paludification, its occurrence, types and main environmental determinants were studied in boreal lakes with varying size (41–560 km2) and total phosphorus content (4.5–35.5 μg L−1) in Finland. The relative importance of catchment characteristics, water quality and water level regulation on paludification was analysed at the lake level (n=20), whereas the importance of site morphology, soil quality and aquatic vegetation was analysed at the site level (n=289). This study utilised two novel statistical methods in numerical analyses: generalised linear mixed models and variation partitioning (VP). Bottom ward overgrowth was the main paludification type in the studied lakes. At the lake level, the magnitude of spring flooding and the altitude of the lake had a negative response to paludification, whereas the existence of water level regulation, cover of clay soil and total phosphorus content correlated positively to paludification. At the site level, the paludification was negatively related to slope angle, and positively to the occurrence of clay soil, Glyceria maxima (reed sweet-grass) and the abundance of eutrophy indicator species. However, a considerable amount of variation in littoral paludification both at lake and site levels was accounted for by the joint effects of predictors and may thus be causally related to two or all three groups of predictors. 相似文献
8.
Factors affecting water chemistry of alpine lakes 总被引：2，自引：0，他引：2
A. Marchetto R. Mosello R. Psenner G. Bendetta A. Boggero D. Tait G. A. Tartari 《Aquatic Sciences - Research Across Boundaries》1995,57(1):81-89
During a four-year study (1988–1991), 413 lakes in the Central Alps (Italy, Switzerland and Austria) were investigated to quantify their acidification. The ionic content of the lakes was generally low: 68% of them had alkalinity values of less than 200 µeq 1–1 and were regarded as sensitive to acidification. Moreover, 36% of the lakes showed alkalinity values of less than 50 µeq 1–1. Redundancy Analysis was used to relate the hydrochemistry of 187 lakes to their catchment characteristics. Calcite weathering was the main factor influencing lake chemistry. The same analysis, applied to a subset of 101 lakes lying in watersheds exclusively composed of silicic rocks, showed that lake chemistry was influenced by silicate weathering and nitrogen uptake. These processes were found to be mainly related to lake altitude and the fraction of the watershed not covered by vegetation, i.e. controlled by temperature. The importance of these relations to explain the pH shift produced by climatic variation is also discussed. 相似文献
9.
Richard E. Lizotte Jr Lindsey M. W. Yasarer Mark K. Griffith Martin A. Locke Ronald L. Bingner 《水文研究》2021,35(2):e14061
Beasley Lake Watershed is an agriculturally influenced drainage basin in western Mississippi that has been intensively studied for 25 years. As part of the USDA Conservation Effects Assessment Project (CEAP), the watershed has archived hydrology, precipitation, and water quality data in order to measure the effects of multiple USDA Natural Resources Conservation Service conservation practices on lake water quality. The long-term database is available to researchers using a web-based application, Sustaining the Earth's Watersheds, Agricultural Research Data System (STEWARDS). STEWARDS is a GIS-based data retrieval application that encompasses spatial and temporal data collected from multiple sites within the watershed. This data note describes information located in the STEWARDS Beasley Lake Watershed database, including hydrology, precipitation, and water quality data. This information is valuable to researchers and agencies beyond the USDA as an available and useful database to improve the understanding of how land-use practices affect the water quality of shallow lake systems. 相似文献
10.
Irrigated agriculture has expanded greatly in the water-rich U.S. northern lake states during the past half century. Source water there is usually obtained from glacial aquifers strongly connected to surface waters, so irrigation has a potential to locally decrease base flows in streams and water levels in aquifers, lakes, and wetlands. During the nascent phase of the irrigation expansion, water availability was explored in works of some fame in the Wisconsin central sands by Weeks et al. (1965) on the Little Plover River and Weeks and Stangland (1971) on "headwater area" streams and lakes. Four decades later, and after irrigation has grown to a dominant landscape presence, we revisited irrigation effects on central sands hydrology. Irrigation effects have been substantial, on average decreasing base flows by a third or more in many stream headwaters and diminishing water levels by more than a meter in places. This explains why some surface waters have become flow and stage impaired, sometimes to the point of drying, with attendant losses of aquatic ecosystems. Irrigation exerts its effects by increasing evapotranspiration by an estimated 45 to 142 mm/year compared with pre-irrigated land cover. We conclude that irrigation water availability in the northern lake states and other regions with strong groundwater-surface water connections is tied to concerns for surface water health, requiring a focus on managing the upper few meters of aquifers on which surface waters depend rather than the depletability of an aquifer. 相似文献
11.
The use of TN:TP and DIN:TP ratios as indicators for phytoplankton nutrient limitation in oligotrophic lakes affected by N deposition 总被引：1，自引：0，他引：1
Ann-Kristin Bergström 《Aquatic Sciences - Research Across Boundaries》2010,72(3):277-281
The stoichiometric composition of lake water chemistry affects nutrient limitation among phytoplankton. I show how TN:TP and
DIN:TP ratios vary in oligotrophic lakes of Europe and the USA affected by different amounts of N deposition, and evaluate
whether the DIN:TP ratio is a better indicator than the TN:TP ratio for discriminating between N and P limitation of phytoplankton.
Data were compiled from boreal and low to high alpine lakes, and comprise epilimnetic lake water chemistry data (106 lakes)
and results from short-term nutrient bioassay experiments (28 lakes). A large share (54%) of the oligotrophic lakes in the
study had low TN:TP mass ratios (<25). DIN:TP ratios showed higher variability than TN:TP ratios. Variability in DIN:TP ratios
was related to N deposition, but also to catchment characteristics. Data from short-term bioassay experiments with separate
addition of N and P showed that the DIN:TP ratio was a better indicator than the TN:TP ratio for N and P limitation of phytoplankton.
Phytoplankton shift from N to P limitation when DIN:TP mass ratios increase from 1.5 to 3.4. High DIN:TP ratios, indicating
P limitation of phytoplankton, were generally found in alpine lakes with low to moderate N deposition and in boreal lakes
with high to very high amounts of N deposition. 相似文献
12.
《Limnologica》2017
The article examines how heads of farmers’ households perceive the socioeconomic benefits of Lake Ziway (Ethiopia), the causes of its current degradation, and the state of land and water use management in its watershed. The investigation was based on in-depth empirical field work including a survey with 635 heads of smallholder farmers’ households via interview using semi-structured questionnaires. Further, water abstraction was estimated from three districts that border with the lake. Respondents believe that Lake Ziway provides a number of individual and collective benefits for local communities, private companies and public institution. They stated, however, that the lake is under pressure from the floriculture industry and other investment projects, high population growth and subsequent expansion of settlements and irrigation farms, high applications of agrochemicals, soil erosion, uncontrolled water abstraction, and deforestation in the watershed. The respondents further believe that these activities are degrading the lake water quality, shrinking its water volume and decreasing its fish population. After examining government’s efforts to address these activities, the majority of respondents believe that the government role in the whole watershed is weak. This study contributes to better understand the local socio-ecological coherences and the problems Lake Ziway and its watershed are facing. It also provides information regarding long-term sustainable land and water use planning strategies for the lake and management of its watershed, which could also be applied to other lakes in Ethiopia, and beyond. 相似文献
13.
Benthic diatoms of an Alpine stream/lake network in Switzerland 总被引：1，自引：0，他引：1
Christopher T. Robinson Barbara Kawecka 《Aquatic Sciences - Research Across Boundaries》2005,67(4):492-506
We compared the benthic diatom composition of lakes, and lake inlet and outlet streams in a high elevation catchment (∼2600
m a.s.l.) in the Swiss Alps. The catchment consisted of a southern basin mostly fed by glacial-melt water and a northern basin
fed by snowmelt and groundwater. Streams in both basins flowed through a series of small lakes before converging into a lake
with a primary outlet channel. The south basin had on average 4°C cooler water temperatures and 2× higher nitrate-N levels
(up to 300 μg/L) than the north basin. In contrast, the north basin had higher levels (2–4×) of particulate-P, particulate-N,
and particulate organic matter than the south basin. A total of 109 and 143 diatom species was identified in lakes and streams,
respectively, with a similar number of species found in each basin. Aulacoseira alpigena and Achnanthidium minutissimum were common benthic algae in north basin lakes, whereas Achnanthes subatomoides, Achnanthes marginulata, Pinnularia microstauron, and Psammothidium helveticum were most common in south basin lakes. One disconnected lake in the north basin had an assemblage dominated by Tabellaria flocculosa (66%) and Eunotia tenella (14%). Principal components analysis showed a clear separation between the north and south basins in lotic diatoms. Of the
10 most common species, streams in the south basin had greater abundances of Psammothidium helveticum, Achnanthes helvetica var. minor, Achnanthes marginulata, Achnanthes subatomoides, and Diatoma mesodon than the north basin, whereas north basin streams had higher abundances of Achnanthidium minutissimum, Aulacoseira alpigena, and Luticola goeppertiana. Lake outlet assemblages were similar to respective downstream lake inlet assemblages, and assemblages changed in composition
along each basins longitudinal flow path. However, Aulacoseira alpigena had higher average abundances in north basin outlets than inlets, and Achnanthidium minutissimum, Psammothidium helveticum, and Achnanthes helvetica var. minor had higher average abundances in south basin outlets than inlets. In contrast, Diatoma mesodon, Fragilaria capucina, and Gomphonema parvulum had higher average abundances in south basin inlets than outlets. The spatial patterns in species composition reflected the
hierarchical interaction of landscape features (geology, hydrology) on longitudinal gradients (lake position) in the stream/lake
network. 相似文献
14.
A modeling approach for assessing the effect of multiple alpine lakes in sequence on nutrient transport 总被引：1，自引：1，他引：0
Dave M. Epstein Bethany T. Neilson Keli J. Goodman David K. Stevens Wayne A. Wurtsbaugh 《Aquatic Sciences - Research Across Boundaries》2013,75(2):199-212
The effects of a single lake on downstream water chemistry may be compounded by the presence of additional lakes within the watershed, augmenting or negating the effects of the first lake. Multiple, linked lakes are a common feature of many watersheds and these resemble reactors in series often studied in engineering. The effects of multiple lakes in series on nutrient transport are largely unexplored. We populated and calibrated a simple lake model to investigate the role of a sub-alpine lake (Bull Trout Lake (BTL), Rocky Mountains, USA) on the transport of the macronutrients during the summer of 2008. Further, we developed a sequential model in which four identical lakes (copies of the BTL model) were connected in series. All lakes in the sequence retarded the flux of nutrients, thus slowing their transport downstream. The first lake in the sequence dramatically altered stream water chemistry and served as a sink for C and P and a source of N, while additional lakes downstream became sources of C, N and P. Although additional downstream lakes resulted in important changes to water chemistry and nutrient transport, the nature of the changes were similar from Lakes 2 to 4 and the magnitude of the changes diminished with distance downstream. Our lake model served as an effective tool for assessing the nutrient budget of the lake and the hypothetical effect of multiple lakes in sequence in a landscape limnology framework. 相似文献
15.
Effects of Watershed Land Use and Lake Morphometry on the Trophic State of Chinese Lakes: Implications for Eutrophication Control 总被引：1，自引：0，他引：1
Water quality in lakes is influenced by a large number of watershed and lake characteristics. In this study, we examined the relative effects of watershed land use and lake morphology on the trophic state of 19 lakes in the Yunnan plateau and lower Yangtze floodplain, the two most eutrophic regions in China. Trophic state parameters consisted of total nitrogen, total phosphorus, chemical oxygen demand, chlorophyll‐a, Secchi depth, and trophic state index, while lake morphometric variables included area, maximum depth, mean depth, water residence time (WRT), volume, and length to width ratio. Percentages of forest, grassland, cropland, unused land, built‐up land, and water body in each lake's watershed were extracted from a land use map interpreted from Landsat TM images. A t‐test indicated that lower Yangtze floodplain lakes were shallower and had higher percentages of cropland and built‐up land in watersheds than Yunnan plateau lakes. Pearson's correlation analysis indicated that both watershed land use and lake morphometric variables were significantly related to most of the trophic state parameters. However, stepwise regression analyses demonstrated that the trophic state of the lower Yangtze floodplain lakes was mainly controlled by the percentages of cropland and built‐up land in watersheds, while that of Yunnan plateau lakes was mostly determined by the lake depth and WRT. These results suggest that the relative effects of watershed land use and lake morphology on lake trophic state are dependent on the lake's location. This study can provide some useful information in watershed land use management for controlling eutrophication in Chinese lakes. 相似文献
16.
《Limnologica》2020
The freshwater microalgal species, Gonyostomum semen, has increased in abundance and distribution in boreal lakes during the past few decades, concerning ecologists and water managers. Due to its rapid spread, G. semen has often been referred to as an invasive species, although it was first described in the 1800s. We hypothesized that G. semen is not an invasive species in Norwegian lakes, and that the increasing success is due to beneficial changes in environmental conditions for this species during the past century. We tested these hypotheses by performing a paleolimnological study of a Norwegian Lake, Skjeklesjøen, with known mass occurrence of G. semen. A specific G. semen pigment biomarker, heteroxanthin, was used to detect this species in layers of a sediment core with known age determinations. Environmental factors in both lake and catchment were further investigated and the relationships with the amounts of G. semen was tested. Our results suggested that G. semen was in fact not an invasive species in this lake the past decades. Several factors were identified as plausible drivers for G. semen in this boreal lake. Between 1874–2016, the increasing levels of G. semen in Lake Skjeklesjøen was most closely correlated with Carbon (C), lake color (measured as absorbance of sediment extracts), Nitrogen (N) and spring temperature. Our results suggest that the rapid increase in G. semen population in this boreal lake over the past 70 years was probably due to a combination of climate change and local anthropogenic activities in the catchment, causing increased browning and increased inputs of organic matter and nutrients. 相似文献
17.
人类活动强度的空间异质性是理解区域人地关系和生态环境效应的基础。基于云南九大高原湖泊流域2020年土地利用数据,构建不同景观类型的人类影响强度系数,运用GIS空间分析量化流域人类活动强度与空间分异,探讨人类活动强度对水质的影响。结果表明:人类活动强度总体特征由高到低依次是杞麓湖(4.83)、星云湖(4.71)、滇池(4.19)、阳宗海(4.11)、抚仙湖(4.03)、异龙湖(4.01)、程海(3.93)、洱海(3.88)和泸沽湖(2.96)。人类活动强度指数(HAI)在流域尺度、坝区尺度、湖岸尺度的空间分异特征明显,每个流域都受到高强度人类活动影响,最大值出现在坝区,滇池、杞麓湖岸线存在完全开发的区域。人类活动强度随海拔和坡度增高而下降,高强度区集中在地势低平的湖泊周围。湖泊营养状态指数与流域尺度和坝区尺度高强度区呈显著正相关,这些区域应作为景观优化和管理的重点;与岸线尺度低强度区呈显著负相关,有必要减少湖滨带人类活动。综合考虑流域地形地貌-人类活动强度-水质的级联效应,应从不同空间尺度对各景观要素与过程管控。鉴于人类活动强度对水质的影响,可把湖泊管理分为预防型、保护型、治理型。 相似文献
18.
In Europe, when small (> 0.01 km2) lakes are considered, approximately 500,000 natural lakes occur. This considerable number points to the fact that lakeshore habitats and ecosystems are of significant importance to the total biodiversity of European landscapes, not only because of their expanse, but also because they are ecotones between land and water, which attract many kinds of wildlife, economical, cultural and recreational uses and human settlement. These very considerable stretches of shore are not currently registered, mapped or evaluated anywhere.Apart from providing habitat, the littoral biocoenosis performs a string of additional functions in the ecosystem, of which several are also of great importance to people, such as self purification, buffer zone, erosion protection and recreation scenery. In particular, the recreational function provides a main economic base for many lake areas and even whole countries in Europe. However, human interests have resulted in lake shore deterioration, such that many European lakes are now bare natural shores or retain only relics of them. Apart from the loss of the ecological functions, this also leads to a substantial loss of economic benefits. This precipitates the need for a responsible management, which can be done only on the base of a sound assessment method and a continuous monitoring of the status of lake shore areas. On a European scale, the European Water Framework Directive (WFD, 2000/60/EC) and the Habitat Directive (92/43/EEC) provide the frame for the assessment and monitoring of the status of littoral habitats of lakes. The WFD focuses on entire surface water bodies, including their associated wetlands under influence of their natural water-level fluctuations. However, the provided set of quality elements has to be adapted for an approach specific to lake shores. Apart from quality elements indicating the natural spatial pre-requisites, biocoenotic diversity and integrity, and ecosystem function and dynamics, also quality elements representing the human pressure of land use and the social and economic value of the lake shore zone should be included in an integrated lakeshore assessment and monitoring concept.However, the application of such an integrated quality assessment scheme requires an integrated administrative counterpart, just as the WFD requires for water management aspects on a catchment scale. Only by overcoming the splitting of competence among a variety of authorities and planning corporations can an integrated approach to sustainable shore development be translated into action. 相似文献
19.
ABSTRACTThe aim of the study was to locate and describe groundwater outflows in a selected lake basin and measure the spring output of water and the physical characteristics of the studied waters (temperature and conductivity). The final aim was to gauge the effects of the spring output on the lake hydrology. The time scope of the work included the period from January 2011 to September 2012. The spatial scope of the work included the area of Lake Raduńskie Górne and its direct catchment located in the Kashubian Lake District in northern Poland. Four groundwater outflows were located in the course of the study. Their total output was 4.6 L s?1 and ranged between 0.5 and 2.5 L s?1. This produces an annual yield of about 145 000 m3 year?1. These results confirm that one of the forms of supply to the lakes are the under-lake springs. For lakes located in the area of young glacial accumulation this can be decisive.
Editor D. Koutsoyiannis Associate editor D. Gerten 相似文献
20.
Mari Ito Myron J. Mitchell Charles T. Driscoll Robert M. Newton Chris E. Johnson Karen M. Roy 《水文研究》2007,21(10):1249-1264
The southwestern Adirondack region of New York receives among the highest rates of atmospheric nitrogen (N) deposition in the USA. Atmospheric N deposition to sensitive ecosystems, like the Adirondacks, may increase the acidification of soils through losses of exchangeable nutrient cations, and the acidification of surface waters associated with enhanced mobility of nitrate (NO3?). However, watershed attributes, including surficial terrestrial characteristics, in‐lake processing, and geological settings, have been found to complicate the relationships between atmospheric N deposition and N drainage losses. We studied two lake‐watersheds in the southwestern Adirondacks, Grass Pond and Constable Pond, which are located in close proximity (～26 km) and receive similarly high N deposition, but have contrasting watershed attributes (e.g. wetland area, geological settings). Since the difference in the influence of N deposition was minimal, we were able to examine both within‐ and between‐watershed influences of land cover, the contribution of glacial till groundwater inputs, and in‐lake processes on surface water chemistry with particular emphasis on N solutes and dissolved organic carbon (DOC). Monthly samples at seven inlets and one outlet of each lake were collected from May to October in 1999 and 2000. The concentrations of NO3? were high at the Grass Pond inlets, especially at two inlets, and NO3? was the major N solute at the Grass Pond inlets. The concentrations of likely weathering products (i.e. dissolved Si, Ca2+, Mg2+, Na+) as well as acid neutralizing capacity and pH values, were also particularly high at those two Grass Pond inlets, suggesting a large contribution of groundwater inputs. Dissolved organic N (DON) was the major N solute at the Constable Pond inlets. The higher concentrations of DON and DOC at the Constable Pond inlets were attributed to a large wetland area in the watershed. The DOC/DON ratios were also higher at the Constable Pond inlets, possibly due to a larger proportion of coniferous forest area. Although DON and DOC were strongly related, the stronger relationship of the proportion of wetland area with DOC suggests that additional factors regulate DON. The aggregated representation of watershed physical features (i.e. elevation, watershed area, mean topographic index, hypsometric‐analysis index) was not clearly related to the lake N and DOC chemistry. Despite distinctive differences in inlet N chemistry, NO3? and DON concentrations at the outlets of the two lakes were similar. The lower DOC/DON ratios at the lake outlets and at the inlets having upstream ponds suggest the importance of N processing and organic N sources within the lakes. Although an inverse relationship between NO3? and DOC/DON has been suggested to be indicative of a N deposition gradient, the existence of this relationship for sites that receive similar atmospheric N deposition suggest that the relationship between NO3? and the DOC/DON ratio is derived from environmental and physical factors. Our results suggest that, despite similar wet N deposition at the two watershed sites, N solutes entering lakes were strongly affected by hydrology associated with groundwater contribution and the presence of wetlands, whereas N solutes leaving lakes were strongly influenced by in‐lake processing. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献