The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Barry T. Hart - One of the best experts on this subject based on the ideXlab platform.
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Uncertainty in Nutrient spiraling : Sensitivity of spiraling indices to small errors in measured Nutrient Concentration
Ecosystems, 2007Co-Authors: Sulfikar Hanafi, Michael R. Grace, J. Angus Webb, Barry T. HartAbstract:Proper assessment of ecological data must consider uncertainty. However, reported estimation of uncertainty in calculated values of Nutrient spiraling indices is rare. Interpretations based on single values of spiraling indices, may therefore be unwittingly flawed. We investigated the sources of analytical uncertainty in the Nutrient Concentrations used to calculate two spiraling indices, uptake length (S w ) and uptake velocity (V f ), and used Monte Carlo Simulation (MCS) to estimate the resultant uncertainty in index values. We also examined the effect of the level of Nutrient enrichment on the magnitude of index uncertainty. Outcomes under high and low Nutrient uptake capacity were compared by performing Nutrient addition experiments in two streams with contrasting ambient Nutrient Concentrations. We found that small differences (or uncertainties) in the average plateau Nutrient Concentration resulted in large uncertainties in spiraling indices. The uncertainty resulted from a combination of small differences in Nutrient Concentrations between upstream and downstream stations (particularly for the low uptake case), the low Nutrient Concentration added into the stream, and the sample matrix and storage. The stream with low Nutrient uptake capacity had larger relative uncertainties in S w than when the Nutrient uptake capacity was high. The presence of such errors demands that S w and V f values should be reported with uncertainty, rather than the normal practice of a single calculated value.
Gunhild Bødtker - One of the best experts on this subject based on the ideXlab platform.
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Microfluidic study of effects of flow velocity and Nutrient Concentration on biofilm accumulation and adhesive strength in the flowing and no-flowing microchannels
Journal of Industrial Microbiology & Biotechnology, 2019Co-Authors: Na Liu, Bente E. Thorbjørnsen, David Landa-marbán, Beate Hovland, Bartek Florczyk Vik, Florin Adrian Radu, Thomas Baumann, Tormod Skauge, Gunhild BødtkerAbstract:Biofilm accumulation in porous media can cause pore plugging and change many of the physical properties of porous media. Engineering bioplugging may have significant applications for many industrial processes, while improved knowledge on biofilm accumulation in porous media at porescale in general has broad relevance for a range of industries as well as environmental and water research. The experimental results by means of microscopic imaging over a T-shape microchannel clearly show that increase in fluid velocity could facilitate biofilm growth, but that above a velocity threshold, biofilm detachment and inhibition of biofilm formation due to high shear stress were observed. High Nutrient Concentration prompts the biofilm growth; however, the generated biofilm displays a weak adhesive strength. This paper provides an overview of biofilm development in a hydrodynamic environment for better prediction and modelling of bioplugging processes associated with porous systems in petroleum industry, hydrogeology and water purification.
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microfluidic study of effects of flow velocity and Nutrient Concentration on biofilm accumulation and adhesive strength in microchannels
bioRxiv, 2018Co-Authors: Na Liu, Bente E. Thorbjørnsen, Beate Hovland, Florin Adrian Radu, Thomas Baumann, Tormod Skauge, David Landamarban, Bartek Vik, Gunhild BødtkerAbstract:Biofilm accumulation in the porous media can cause plugging and change many physical properties of porous media. Up to now, applications of desired biofilm growth and its subsequent bioplugging have been attempted for various practices. A deeper understanding of the relative influences of hydrodynamic conditions including flow velocity and Nutrient Concentration, on biofilm growth and detachment is necessary to plan and analyze bioplugging experiments and field trials. The experimental results by means of microscopic imaging over a T-shape microchannel show that flow velocity and Nutrient Concentrations can have significant impacts on biofilm accumulation and adhesive strength in both flowing and stagnant microchannels. Increase in fluid velocity could facilitate biofilm growth, but that above a velocity threshold, biofilm detachment and inhibition of biofilm formation due to high shear stress were observed. High Nutrient Concentration prompts the biofilm growth, but was accompanied by a relatively weak adhesive strength. This research provides an overview of biofilm development in a hydrodynamic environment for better predicting and modelling the bioplugging associated with porous system in petroleum industry, hydrogeology, and water purification.
Jaap Sinninghe S Damste - One of the best experts on this subject based on the ideXlab platform.
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effects of temperature ph and Nutrient Concentration on branched gdgt distributions in east african lakes implications for paleoenvironmental reconstruction
Organic Geochemistry, 2014Co-Authors: Shannon E Loomis, James M Russell, Hilde Eggermont, Dirk Verschuren, Jaap Sinninghe S DamsteAbstract:Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are membrane lipids found in soils and sediments and their relative abundance correlates with temperature and pH, enabling them to be used as proxies in reconstructing past climatic and environmental conditions. However, the potential for other environmental variables, such as Nutrient Concentration, to affect brGDGT distributions remains largely unexplored. We have examined the influence of a suite of environmental factors, including temperature, lake water and sediment chemistry, and lake morphometry on brGDGT Concentration and distributions in the surface sediments of 111 lakes in East Africa. We found that temperature was the major control on the distributions, while the influence of pH was relatively minor. Water depth also had a minor but statistically significant influence, perhaps due to the relationship between lake depth and deep water anoxia. Water column Nutrient Concentration did not have a significant effect on the distributions or Concentration. We further explored the potential for these variables to affect brGDGT temperature reconstruction by examining the correlation between them and the residuals of our brGDGT temperature calibration. We found that, while the distribution of some cyclized brGDGTs may be influenced by pH and other environmental variables, they are necessary in brGDGT calibration equations in order to accurately reconstruct temperature, likely due to covariation between temperature and other environmental variables. While surface water pH correlated with the relative abundance of certain brGDGTs, caution should be exhibited when using brGDGTs as a pH proxy because of systematic calibration errors.
Jonathan M. Adams - One of the best experts on this subject based on the ideXlab platform.
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Predictable communities of soil bacteria in relation to Nutrient Concentration and successional stage in a laboratory culture experiment.
Environmental microbiology, 2015Co-Authors: Woojin Song, Mincheol Kim, Binu M. Tripathi, Hyoki Kim, Jonathan M. AdamsAbstract:It is difficult to understand the processes that structure immensely complex bacterial communities in the soil environment, necessitating a simplifying experimental approach. Here, we set up a microcosm culturing experiment with soil bacteria, at a range of Nutrient Concentrations, and compared these over time to understand the relationship between soil bacterial community structure and time/Nutrient Concentration. DNA from each replicate was analysed using HiSeq2000 Illumina sequencing of the 16S rRNA gene. We found that each Nutrient treatment, and each time point during the experiment, produces characteristic bacterial communities that occur predictably between replicates. It is clear that within the context of this experiment, many soil bacteria have distinct niches from one another, in terms of both Nutrient Concentration, and successional time point since a resource first became available. This fine niche differentiation may in part help to explain the coexistence of a diversity of bacteria in soils. In this experiment, we show that the unimodal relationship between Nutrient Concentration/time and species diversity often reported in communities of larger organisms is also evident in microbial communities.
Josep Peñuelas - One of the best experts on this subject based on the ideXlab platform.
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Factors affecting Nutrient Concentration and stoichiometry of forest trees in Catalonia (NE Spain)
Forest Ecology and Management, 2011Co-Authors: Jordi Sardans, Albert Rivas-ubach, Josep PeñuelasAbstract:Although some studies have observed significant correlations between latitude and climate gradients and tree leaf Nutrient Concentration and stoichiometry, others have not. This study examined the Nutrient Concentrations of tree leaves in 3530 plots of the Catalonian Forest Inventory. Catalonia is a Mediterranean region located in NE Iberian Peninsula. It has a long land-use history and includes the large industrial-urban area of Barcelona but still contains a large forest area (42%). In the forests of Catalonia, leaf Nutrient Concentration increased and leaf C:Nutrient ratios decreased from south to north, which paralleled the increase in MAP (mean annual precipitation) and the decrease in MAT (mean annual temperature), which was expected in a Mediterranean climate where the availability of water is the most limiting factor for plant Nutrient uptake. In addition, the availability of water, which influences productivity, was associated with low leaf N:P content ratios, which is consistent with the Growth Rate Hypothesis. At a regional scale, the results support the Soil-Age Hypothesis because the youngest soils in the Pyrenees had the lowest leaf N:P ratios. Furthermore, the type of forest (evergreen, deciduous, or coniferous) explained some of the variation in leaf Nutrient Concentrations and stoichiometry. Nutrient Concentrations were highest in deciduous trees and lowest in coniferous trees. Leaf Nutrient Concentrations and stoichiometry were mainly correlated with climate, but other factors such as the chemical properties of soil and rock, phylogenetics, and different ecological histories and anthropogenic factors such as pollution, had an effect.
