The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
C M Cooper - One of the best experts on this subject based on the ideXlab platform.
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three dimensional numerical modeling of cohesive sediment transport and wind wave impact in a shallow Oxbow Lake
Advances in Water Resources, 2008Co-Authors: Xiaobo Chao, Yafei Jia, Douglas F Shields, Sam S Y Wang, C M CooperAbstract:It was observed that in some closed inland Lakes sediment transport was dominated by wind-induced currents, and the sediment resuspension was primarily driven by wind-induced waves. This paper presents the development and application of a three-dimensional numerical model for simulating cohesive sediment transport in water bodies where wind-induced currents and waves are important. In the model, the bottom shear stresses induced by currents and waves were calculated, and the processes of resuspension (erosion), deposition, settling, etc. were considered. This model was first verified by a simple test case consisting of the movement of a non-conservative tracer in a prismatic channel with uniform flow, and the model output agreed well with the analytical solution. Then it was applied to Deep Hollow Lake, a small Oxbow Lake in Mississippi. Simulated sediment concentrations were compared with available field observations, with generally good agreement. The transport and resuspension processes of cohesive sediment due to wind-induced current and wave in Deep Hollow Lake were also discussed.
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numerical modeling of water quality and sediment related processes
Ecological Modelling, 2007Co-Authors: Xiaobo Chao, Yafei Jia, Douglas F Shields, Sam S Y Wang, C M CooperAbstract:Abstract A three-dimensional water quality model (CCHE3D_WQ) was developed for simulating temporal and spatial variations of water quality with respect to phytoplankton, nutrients, and dissolved oxygen. Four major interacting systems were simulated, including phytoplankton dynamics, nitrogen cycle, phosphorus cycle, and dissolved oxygen balance. The effects of suspended and bed sediment on the water quality processes were also considered. The model was verified using analytical solutions for the transport of non-conservative substances in open channel flow, and then calibrated and validated by applying it to the study of the water quality of a natural shallow Oxbow Lake. The simulated time serial concentration of phytoplankton (as chlorophyll) and nutrients were generally in good agreement with field observations. Sensitivity studies were then conducted to demonstrate the impacts on water quality due to varying nutrients and suspended sediment loads to the chlorophyll concentration.
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development and application of a phosphorus model for a shallow Oxbow Lake
Journal of Environmental Engineering, 2006Co-Authors: Xiaobo Chao, Yafei Jia, C M Cooper, Douglas F Shields, Sam S Y WangAbstract:A three-dimensional numerical model was developed for simulating the phosphorus concentration in shallow Lakes. In this model, the computational domain was divided into two parts: the water column and the bed sediment layer. The processes of mineralization, settling, adsorption, desorption, bed release (diffusion), growth, and death of phytoplankton were taken into account, and the concentration of organic phosphorus, phosphate, and related water quality constituents was simulated. The concentrations of adsorbed (particulate) and dissolved phosphate due to adsorption-desorption were calculated using two formulas derived based on the Langmuir equation. The release rate of phosphorus from the bed sediment layer was calculated by considering the effects of the concentration gradient across the water-sediment interface, pH, temperature, dissolved oxygen concentration, and flow conditions. The adsorption and desorption of phosphate from sediment particles, as well as its release from bed sediment, were verified using laboratory experimental data. The model was calibrated and applied to Deep Hollow Lake in the Mississippi alluvial plain. The simulated trends and magnitudes of phosphorus concentration were compared with field observations. The simulation results show that there are strong interactions between sediment-related processes and phosphorus concentration.
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numerical modeling of the phosphorus cycle in a shallow Oxbow Lake
World Water and Environmental Resources Congress 2005, 2005Co-Authors: Xiaobo Chao, Yafei Jia, C M Cooper, Douglas F ShieldsAbstract:A three-dimensional model was developed for simulating the phosphorus concentration in a shallow Oxbow Lake. The processes of mineralization, settling, adsorption, desorption, bed release (diffusion), growth and death of phytoplankton, etc, were considered, and the concentration of organic phosphorus, orthophosphate and phytoplankton were simulated. The adsorption and desorption of phosphorus from suspended sediment particles, as well as its release from bed sediment were verified using results obtained from laboratory experiments. The model was calibrated and applied to Deep Hollow Lake in the Mississippi alluvial plain. Simulated trends and magnitudes are generally in good agreement with field observations. Simulation indicates strong interactions between sediment-related processes and phosphorus concentration.
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surface water ground water and sediment quality in three Oxbow Lake watersheds in the mississippi delta agricultural region pesticides
International journal of ecology and environmental sciences, 2003Co-Authors: C M Cooper, Sammie Smith, Matthew T MooreAbstract:We measured residual and current use pesticides in shallow groundwater, surface water, and Lake sediment in three Oxbow Lakes and their watersheds in the intensively cultivated alluvial plain of the Mississippi River, USA. The three-year study focussed on providing knowledge of pesticide movement and concentrations from intensive agricultural production into aquatic ecosystems and evaluating the degree of contaminant deposition and persistence in Oxbow Lake sediments. Penetration of insecticides into shallow groundwater did not represent a hazard. Herbicides and insecticides were found in surface water as a result of rainfall-related runoff from farm fields. A common herbicide, atrazine, had the largest number of detections (28% of Lake water samples). Sediment cores taken for pesticide analysis were also viewed by age in each Lake. Residual organochlorines dominated the pesticide sediment profile. DDT and its metabolites were the only compounds that permeated sediments at all sites. Sediments deposited in the 1960s and 1970s which contained higher concentrations of DDT have been effectively sealed by more recent material so that the sink of contaminant is unavailable to the water column. Controlled release of pyrethroid insecticides in a forested wetland showed that the wetland was totally effective in neutralizing the pyrethroids before they reached Lake surface water. The Lakes are designated for fish and wildlife use, but pesticides seldom exceeded more stringent drinking water standards. Acute toxicity concerns lessen as more conservation measures are installed on and off fields. Additionally, DDT metabolites continue to slowly degrade. A suite of protective measures is necessary to protect downstream water resources from runoff-related contamination.
Monika Karpinskakolaczek - One of the best experts on this subject based on the ideXlab platform.
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persist or take advantage of global warming a development of early holocene riparian forest and Oxbow Lake ecosystems in central europe
Quaternary Science Reviews, 2018Co-Authors: Piotr Kolaczek, Mariusz Galka, Mateusz Plociennik, Karina Apolinarska, Kamila Tosik, Michal Gąsiorowski, Stephen J Brooks, Monika KarpinskakolaczekAbstract:Abstract In this study, we focus on the environmental changes recorded in the San River valley (Stubno–Naklo site, south-eastern Poland) at the beginning of the Holocene. This multi-proxy study for the first time in the region of the northern foreland of the Western Carpathians included quantitative thermal reconstruction based on Chironomidae and high-stratigraphic resolution of 14C AMS dating. We hypothesised that (i) climate events during the Early Holocene contributed to ecosystem turnovers via stimulating disturbances related to the river's fluvial activity and (ii) woodland and Oxbow Lake ecosystems became more resilient to flood disturbances along with the advance of forest succession on the floodplain. The results revealed that the response of ecosystems on the Early Holocene warming was strongly linked with the decrease in fluvial activity of the river. The reconstruction of the mean July temperature based on Chironomidae revealed the exceptionally high rate of warming during the period of ca. 11,490–11,460 cal. BP (at least 1 °C per decade) up to values > 2 °C than modern ones. During this period, the Lake trophy and productivity started to increase with a simultaneous spread of Betula woodlands on the alluvial plain. The “Preboreal oscillation” cooling was dated at ca. 11,450–11,250 cal. BP. At that time, an increased climate instability led to a higher rate of extremal events such as flood at ca. 11,400–11,330 cal. BP, which probably led to the disruption of the Betula population. The development of riparian woodlands, initiated by the expansion of Ulmus from ca. 11,100 cal. BP, and further spread of Quercus and Fraxinus excelsior on the alluvial plain and lower river terraces increased plant transpiration and therefore limited the river runoff and its fluvial activity. This, together with the expansion of reed belt communities, probably limited the impact of floods on the Oxbow Lake. However, ca. 10,010–9880 cal. BP traces of higher fluvial activity, but of lower impact, were recorded.
F A Esteves - One of the best experts on this subject based on the ideXlab platform.
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influence of water level variation on fertilization of an Oxbow Lake of rio mogi guacu state of sao paulo brazil
Hydrobiologia, 1995Co-Authors: Antonio Fernando Monteiro Camargo, F A EstevesAbstract:Variation in water level in Lagoa do Mato, an Oxbow Lake of the Rio Mogi-Guacu, fertilized the water column with phosphorus, nitrogen and silicates during periods when the waters of the Rio Mogi-Guacu overflowed to the Lake. An increase in electrical conductivity and a reduction in transparency was also observed. After fertilization, the nutrients declined rapidly, remaining low until the next floods. Principal component analysis revealed three distinct periods relative to the concentration of nutrients,i.e. a fertilization period, an assimilation period, and a period of stocking in biomass. These results are discussed in relation to other Oxbow Lakes, in an attempt to identify ecological factors responsible for the fertilization of these ecosystems.
Bela Tothmeresz - One of the best experts on this subject based on the ideXlab platform.
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community response of cladocera to trophic stress by biomanipulation in a shallow Oxbow Lake
Water, 2019Co-Authors: Csaba Berta, János Korponai, Bela Tothmeresz, Marta Wojewodka, Olga Augustyniuk, Boglarka Bertalanbalazs, Alex Sandor Nagy, Istvan Grigorszky, István GyulaiAbstract:Studying contemporary and subfossil Cladocera (Crustacea) communities, we explored the effect of top-down stressors on the cladoceran communities; we are also interested in the coherence of the contemporary and subfossil communities. The studied Cibakhaza Oxbow Lake is in E Hungary, on the left-floodplain of the River Tisza; it is a large, long, and shallow Oxbow Lake. Three areas of the Oxbow Lake were distinguished based on the strength of top-down stress: protected area with low top-down stress, biomanipulated area with high top-down stress, and recreational area with moderate top-down stress. Altogether, we identified 28 taxa in the contemporary and subfossil communities in the Oxbow Lake. We found that the species number of the contemporary Cladocera communities was lower (protected area: 13; biomanipulated area: 9, and recreational area: 14) than in the subfossil communities (protected area: 20; biomanipulated area: 16, and recreational area: 14). Among the environmental variables, we observed differences between the protected and biomanipulated area, while the recreational area showed a transition. Species number, abundances, and Simpson diversity also showed the effect of the fish introduction. There were no differences in beta-diversity among the contemporary and subfossil Cladocera community. The non-metric multidimensional scaling (NMDS) ordination showed that the biomanipulated area in the case of the contemporary communities was separated from the other areas, while in the case of the subfossil communities, there was no separation according to top-down stress. Our results showed that the number of species of contemporary Cladocera communities was lower in each area (3–10; 3–9; 5–9) compared to the subfossil communities (6–17; 7–12; 8–12). However, the highest abundances were found in the biomanipulated area due to the appearance of small-sized Cladocera species. Our findings suggest that the effect of a short-time fish introduction is restorable when the Oxbow Lake has a protected part.
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Contribution of phytoplankton functional groups to the diversity of a eutrophic Oxbow Lake
Hydrobiologia, 2019Co-Authors: Judit Görgényi, Bela Tothmeresz, Gábor Várbíró, András Abonyi, Enikő T-krasznai, Viktoria B-béres, Gábor BoricsAbstract:The functional group (FG) concept suggests that species having different phylogenetic origins but possessing similar functional characteristics can be considered as functional groups and these co-occur in the phytoplankton. Here, we study how functional redundancy of phytoplankton taxa (within group richness) contribute to the species diversity of assemblages in an Oxbow Lake in the Carpathian Basin. We found that although the observed functional redundancy was similar among several FGs, the shape of the species accumulation curves of these groups was considerably different, implying that the observed species numbers alone do not represent the real functional redundancy of the groups. We demonstrated that FGs that showed asymptotes in species richness estimates in small spatial scale, exhibited steady increase in large spatial, and temporal scales. The contribution of FGs to species richness depended strongly on the relative biomass of each FG. Species accumulation curves of those groups of which elements dominated in the phytoplankton, appeared to be approaching asymptotes. Since the shapes of species accumulation curves refer to the strengths of within-group competition among constituent species, our results imply that functional redundancy of phytoplankton is influenced by the role that the elements play within the assemblages.
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small scale macrophyte environment relationship in an Oxbow Lake of the upper tisza valley hungary
Community Ecology, 2011Co-Authors: Balazs Andras Lukacs, Gy. Dévai, Bela TothmereszAbstract:We tested the relationship between water chemical variables and macrophyte vegetation in an Oxbow-Lake of the Upper-Tisza, Hungary. There were 42 releves in random plots of 2 m by 2 m and 20 chemical variables (Ca, Fe, Hydrogencarbonate, K, carbonate, Kjeldahl-nitrogen, chloride, COD(Cr), Mg, m-alkalinity, Mn, Na, NH4, NO2, NO3, dissolved orthophosphate-P, total phosphorus, pH, sulphate and conductivity) and a biological one (chlorophyll a) were measured. Detrended canonical correspondence analysis was used to explore the species-vegetation-water chemical variables relationship. Our results revealed that there were pronounced differences both in the vegetation and the chemical variables among the different kinds of vegetation patches. According to the DCCA, Trapetum natantis, Glycerietum maximae, Ceratophyllo-Nymphaeetum albae and Typhetum angustifoliae associations could be separated based on the releves and environmental variables. Kjeldahl nitrogen and carbonate were found to be the most important variables. Our results suggest that water chemical variables had strong influence on vegetation development. The groups of releves identified by the DCCA were coherent with classical phytosociological categories.
Antonio Fernando Monteiro Camargo - One of the best experts on this subject based on the ideXlab platform.
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influence of water level variation on biomass and chemical composition of the aquatic macrophyte eichhornia azurea kunth in an Oxbow Lake of the rio mogi guacu sao paulo brazil
Archiv Fur Hydrobiologie, 1996Co-Authors: Antonio Fernando Monteiro Camargo, Francisco De Assis EstevesAbstract:The influence of water level variation (flood pulse) on the biomass and chemical composition of the aquatic macrophyte Eichhornia azurea, was investigated in a tropical Oxbow Lake of the Rio Mogi-Guacu, State of Sao Paulo, Brazil. The flood pulse causes an increase in total nitrogen content from 0.67 to 1.35 mg/L and total phosphorus content from 10.5 to 101.0 μg/L of the water. This fertilization, associated with other factors, determines a typical seasonal variation in the biomass and chemical composition of the macrophyte.
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influence of water level variation on fertilization of an Oxbow Lake of rio mogi guacu state of sao paulo brazil
Hydrobiologia, 1995Co-Authors: Antonio Fernando Monteiro Camargo, F A EstevesAbstract:Variation in water level in Lagoa do Mato, an Oxbow Lake of the Rio Mogi-Guacu, fertilized the water column with phosphorus, nitrogen and silicates during periods when the waters of the Rio Mogi-Guacu overflowed to the Lake. An increase in electrical conductivity and a reduction in transparency was also observed. After fertilization, the nutrients declined rapidly, remaining low until the next floods. Principal component analysis revealed three distinct periods relative to the concentration of nutrients,i.e. a fertilization period, an assimilation period, and a period of stocking in biomass. These results are discussed in relation to other Oxbow Lakes, in an attempt to identify ecological factors responsible for the fertilization of these ecosystems.
