scholarly journals Contrasting trends in element incorporation in hyaline and miliolid foraminifera

2016 ◽  
Author(s):  
Inge van Dijk ◽  
Lennart de Nooijer ◽  
Gert-Jan Reichart
Keyword(s):  
Trace Elements ◽  
Calcium Channels ◽  
Membrane Transport ◽  
Transport Model ◽  
Free Ions ◽  
Element Partitioning ◽  
The Impact ◽  
Carbonate Complexes ◽  
Similar Element

Abstract. We analyzed trends in element incorporation between hyaline (perforate) and miliolid (imperforate) foraminifera in order to investigate processes involved in calcification affecting element incorporation into foraminiferal carbonate. For both groups, we observed similar trends in element incorporation with pCO2, suggesting there some mechanisms to transports ions to the site of calcification are similar for both calcification pathways, although the impact might be different across species. A previously published trans-membrane transport model assumes foraminifera utilize Ca2+ channels to transport calcium to the site of calcification. These channels are somewhat a-specific, leading to (accidental) transport of other free ions. By modelling the activity of free ions as a function of pCO2, we observed that speciation of some elements (like Zn and Ba) are heavily influenced by the formation of carbonate complexes. This leads to an increase in availability of free Zn and Ba with increasing pCO2, which leads to more transport to the site of calcification and subsequently incorporation in the foraminiferal shell. We further observed that incorporation of the trace elements studied here is positively correlated between the hyaline test building species. This could be due to dissimilar activity and/or selectivity of calcium channels between species, perhaps due to differences in size. For miliolid calcification, part of the calcium is obtained not only through channels but by also included seawater vesicles, which leads to similar element to calcium ratios between species and element partitioning which is more in line with inorganic carbonates.

scholarly journals Trends in element incorporation in hyaline and porcelaneous foraminifera as a function of <i>p</i>CO<sub>2</sub>

2017 ◽  
Vol 14 (3) ◽  
pp. 497-510 ◽  
Author(s):  
Inge van Dijk ◽  
Lennart J. de Nooijer ◽  
Gert-Jan Reichart
Keyword(s):  
Benthic Foraminifera ◽  
Carbonate Chemistry ◽  
Larger Benthic Foraminifera ◽  
Element Uptake ◽  
Free Ions ◽  
Seawater Carbonate Chemistry ◽  
The Impact ◽  
Mg Content ◽  
Carbonate Complexes

Abstract. In this study we analyzed the impact of seawater carbonate chemistry on the incorporation of elements in both hyaline and porcelaneous larger benthic foraminifera. We observed a higher incorporation of Zn and Ba when pCO2 increases from 350 to 1200 ppm. Modeling the activity of free ions as a function of pCO2 shows that speciation of some elements (like Zn and Ba) is mainly influenced by the formation of carbonate complexes in seawater. Hence, differences in foraminiferal uptake of these might be related primarily by the speciation of these elements in seawater. We investigated differences in trends in element incorporation between hyaline (perforate) and porcelaneous (imperforate) foraminifera in order to unravel processes involved in element uptake and subsequent foraminiferal calcification. In hyaline foraminifera we observed a correlation of element incorporation of different elements between species, reflected by a general higher incorporation of elements in species with higher Mg content. Between porcelaneous species, inter-element differences are much smaller. Besides these contrasting trends in element incorporation, however, similar trends are observed in element incorporation as a function of seawater carbonate chemistry in both hyaline and porcelaneous species. This suggests similar mechanisms responsible for the transportation of ions to the site of calcification for these groups of foraminifera, although the contribution of these processes might differ across species.

scholarly journals Development of a Component-Level Hydrogen Transport Model with OpenFOAM and Application to Tritium Transport Inside a DEMO HCPB Breeder

2021 ◽  
Vol 11 (8) ◽  
pp. 3481
Author(s):  
Volker Pasler ◽  
Frederik Arbeiter ◽  
Christine Klein ◽  
Dmitry Klimenko ◽  
Georg Schlindwein ◽  
...  
Keyword(s):  
Transport Model ◽  
Tritium Concentration ◽  
Minor Role ◽  
Specific Rate ◽  
Component Level ◽  
Diffusion Limited ◽  
Purge Gas ◽  
Choice Of Species ◽  
The Impact ◽  
Tritium Transport

This work continues the development of a numerical model to simulate transient tritium transport on the breeder zone (BZ) level for the EU helium-cooled pebble bed (HCPB) concept for DEMO. The basis of the model is the open-source field operation and manipulation framework, OpenFOAM. The key output quantities of the model are the tritium concentration in the purge gas and in the coolant and the tritium inventory inside the BZ structure. New model features are briefly summarized. As a first relevant application a simulation of tritium transport for a single pin out of the KIT HCPB design for DEMO is presented. A variety of scenarios investigates the impact of the permeation regime (diffusion-limited vs. surface-limited), of an additional hydrogen content of 300 Pa H2 in the purge gas, of the released species (HT vs. T2), and of the choice of species-specific rate constants (recombination constant of HT set twice as for H2 and T2). The results indicate that the released species plays a minor role for permeation. Both permeation and inventory show a considerable dependence on a possible hydrogen addition in the purge gas. An enhanced HT recombination constant reduces steel T inventories and, in the diffusion-limited case, also permeation significantly. Scenarios with 80 bar vs. 2 bar purge gas pressure indicate that purge gas volumetric flow is decisive for permeation.

scholarly journals The Environmental Effects of the April 2020 Wildfires and the Cs-137 Re-Suspension in the Chernobyl Exclusion Zone: A Multi-Hazard Threat

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 467
Author(s):  
Rocío Baró ◽  
Christian Maurer ◽  
Jerome Brioude ◽  
Delia Arnold ◽  
Marcus Hirtl
Keyword(s):  
Air Quality ◽  
Nuclear Power ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Point Of View ◽  
Plume Dispersion ◽  
Exclusion Zone ◽  
Fire Plume ◽  
Mean Values ◽  
The Impact

This paper demonstrates the environmental impacts of the wildfires occurring at the beginning of April 2020 in and around the highly contaminated Chernobyl Exclusion Zone (CEZ). Due to the critical fire location, concerns arose about secondary radioactive contamination potentially spreading over Europe. The impact of the fire was assessed through the evaluation of fire plume dispersion and re-suspension of the radionuclide Cs-137, whereas, to assess the smoke plume effect, a WRF-Chem simulation was performed and compared to Tropospheric Monitoring Instrument (TROPOMI) satellite columns. The results show agreement of the simulated black carbon and carbon monoxide plumes with the plumes as observed by TROPOMI, where pollutants were also transported to Belarus. From an air quality and health perspective, the wildfires caused extremely bad air quality over Kiev, where the WRF-Chem model simulated mean values of PM2.5 up to 300 µg/m3 (during the first fire outbreak) over CEZ. The re-suspension of Cs-137 was assessed by a Bayesian inverse modelling approach using FLEXPART as the atmospheric transport model and Ukraine observations, yielding a total release of 600 ± 200 GBq. The increase in both smoke and Cs-137 emissions was only well correlated on the 9 April, likely related to a shift of the focus area of the fires. From a radiological point of view even the highest Cs-137 values (average measured or modelled air concentrations and modelled deposition) at the measurement site closest to the Chernobyl Nuclear Power Plant, i.e., Kiev, posed no health risk.

scholarly journals Impacts of Long- and Short-Term of Irrigation with Treated Wastewater and Synthetic Fertilizers on the Growth, Biomass, Heavy Metal Content, and Energy Traits of Three Potential Bioenergy Crops in Arid Regions

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3037
Author(s):  
Mahmoud F. Seleiman ◽  
Nasser Al-Suhaibani ◽  
Salah El-Hendawy ◽  
Kamel Abdella ◽  
Majed Alotaibi ◽  
...  
Keyword(s):  
Trace Elements ◽  
Arid Regions ◽  
Biomass Energy ◽  
Recommended Dose ◽  
Treated Wastewater ◽  
Bioenergy Crops ◽  
Virgin Soil ◽  
Field Crops ◽  
Synthetic Fertilizers ◽  
The Impact

The availability of suitable water is an important factor for increasing the cultivated areas and sustainability in arid (i.e., less than 200 mm precipitation per year) and semiarid regions (i.e., 200–700 mm precipitation per year). Therefore, this study aimed to analyze the impact of treated wastewater (TWW) and groundwater (GW) as well as synthetic fertilizers (50% and 100% of the recommended NPK dose; 150–150–60 kg N–P2O5–K2O ha−1) on the growth, biomass, energy traits, and macro and trace elements of maize (Zea mays L.), sorghum (Sorghum bicolor L.), and pearl millet (Pennisetum glaucum L) grown in old cultivated (first location; L1) and virgin soil (L2 and L3) as potential bioenergy crops. The soil in L1 has been irrigated with treated wastewater for the last 15 years and continued to be irrigated with treated wastewater in this investigation. The virgin soil was divided into two parts: the first part was irrigated with TWW, and the second part was irrigated with GW. The experiments were laid out in a split-plot with a randomized complete block design with water treatments (TWW in old and virgin soil, and GW in virgin soil) in main plots, and the two treatments of fertilization (50% and 100% of the recommended NPK dose) were distributed randomly in subplots. Compared with the crops irrigated with GW, the crops irrigated with TWW, whether grown on old or virgin soil, showed higher plant height, total chlorophyll content, leaf area per plant, total biomass, energy content, and gross energy with low ash. They also contained higher (but lower than permissible limits) concentrations of macro-elements (NPK) and trace elements (Fe, Mn, Cu, Zn, Cd, Pb, Ni, and Co). In addition, the application of a 50% recommended dose of NPK with TWW showed equivalent results to a 100% recommended dose of NPK on all measured parameters with few exceptions. In conclusion, the TWW can be used to irrigate field crops allocated for bioenergy production in arid regions because it does not harm the plants and environment. In addition, the 50% recommended dose of NPK fertilizer exerted no negative effects on the growth and energy production of field crops, thereby protecting the environment and reducing the leaching of excessive fertilizers into GW.

scholarly journals Nitrogen Mass Balance and Pressure Impact Model Applied to an Urban Aquifer

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1171 ◽  
Author(s):  
Mitja Janža ◽  
Joerg Prestor ◽  
Simona Pestotnik ◽  
Brigita Jamnik
Keyword(s):  
Groundwater Quality ◽  
Urban Areas ◽  
Transport Model ◽  
Nitrate Concentration ◽  
Impact Model ◽  
Sewer System ◽  
Management Measures ◽  
Pressure Impact ◽  
The Impact ◽  
The City

The assurance of drinking water supply is one of the biggest emerging global challenges, especially in urban areas. In this respect, groundwater and its management in the urban environment are gaining importance. This paper presents the modeling of nitrogen load from the leaky sewer system and from agriculture and the impact of this pressure on the groundwater quality (nitrate concentration) in the urban aquifer located beneath the City of Ljubljana. The estimated total nitrogen load in the model area of 58 km2 is 334 ton/year, 38% arising from the leaky sewer system and 62% from agriculture. This load was used as input into the groundwater solute transport model to simulate the distribution of nitrate concentration in the aquifer. The modeled nitrate concentrations at the observation locations were found to be on average slightly lower (2.7 mg/L) than observed, and in general reflected the observed contamination pattern. The ability of the presented model to relate and quantify the impact of pressures from different contamination sources on groundwater quality can be beneficially used for the planning and optimization of groundwater management measures for the improvement of groundwater quality.

Predictive membrane transport model for nanofiltration processes in water treatment

AIChE Journal ◽  
2001 ◽  
Vol 47 (6) ◽  
pp. 1346-1362 ◽  
Author(s):  
Shih-Chieh Tu ◽  
Varadarajan Ravindran ◽  
Walter Den ◽  
Massoud Pirbazari
Keyword(s):  
Water Treatment ◽  
Membrane Transport ◽  
Transport Model

The measurement of groundwater temperature in shallow piezometers and standpipes

2005 ◽  
Vol 42 (5) ◽  
pp. 1377-1390 ◽  
Author(s):  
Matthew D Alexander ◽  
Kerry TB MacQuarrie
Keyword(s):  
Finite Element ◽  
Statistical Analysis ◽  
Transport Model ◽  
Shallow Groundwater ◽  
Subsurface Temperature ◽  
Groundwater Temperature ◽  
Monitoring Well ◽  
Laboratory Results ◽  
The Impact

Accurate measurements of in situ groundwater temperature are important in many groundwater investigations. Temperature is often measured in the subsurface using an access tube in the form of a piezometer or monitoring well. The impact of standpipe materials on the conduction of heat into the subsurface has not previously been examined. This paper reports on the results of a laboratory experiment and a field experiment designed to determine if different standpipe materials or monitoring instrument configurations preferentially conduct heat into the shallow sub surface. Simulations with a numerical model were also conducted for comparison to the laboratory results. Statistical analysis of the laboratory results demonstrates that common standpipe materials, such as steel and polyvinylchloride (PVC), do not affect temperature in the subsurface. Simulations with a finite element flow and heat transport model also confirm that the presence of access tube materials does not affect shallow groundwater temperature measurements. Field results show that different instrument configurations, such as piezometers and water and air filled and sealed well points, do not affect subsurface temperature measurements.Key words: groundwater temperature, temperature measurement, conduction, piezometers, piezometer standpipes, thermal modelling.

Impact of the Depth-to-Width Ratio of Periodically Stratified Tidal Channels on the Estuarine Circulation

2015 ◽  
Vol 45 (8) ◽  
pp. 2048-2069 ◽  
Author(s):  
Elisabeth Schulz ◽  
Henk M. Schuttelaars ◽  
Ulf Gräwe ◽  
Hans Burchard
Keyword(s):  
Eddy Viscosity ◽  
Transport Model ◽  
Stable Stratification ◽  
Estuarine Circulation ◽  
Width Ratio ◽  
Cross Sectional ◽  
Tidal Straining ◽  
The Individual ◽  
Periodic Stratification ◽  
The Impact

AbstractThe dependency of the estuarine circulation on the depth-to-width ratio of a periodically, weakly stratified tidal estuary is systematically investigated here for the first time. Currents, salinity, and other properties are simulated by means of the General Estuarine Transport Model (GETM) in cross-sectional slice mode, applying a symmetric Gaussian-shaped depth profile. The width is varied over four orders of magnitude. The individual along-channel circulation contributions from tidal straining, gravitation, advection, etc., are calculated and the impact of the depth-to-width ratio on their intensity is presented and elucidated. It is found that the estuarine circulation exhibits a distinct maximum in medium-wide channels (intermediate depth-to-width ratio depending on various parameters), which is caused by a maximum of the tidal straining contribution. This maximum is related to a strong tidal asymmetry of eddy viscosity and shear created by secondary strain-induced periodic stratification (2SIPS): in medium channels, transverse circulation generated by lateral density gradients due to laterally differential longitudinal advection induces stable stratification at the end of the flood phase, which is further increased during ebb by longitudinal straining (SIPS). Thus, eddy viscosity is low and shear is strong in the entire ebb phase. During flood, SIPS decreases the stratification so that eddy viscosity is high and shear is weak. The circulation resulting from this viscosity–shear correlation, the tidal straining circulation, is oriented like the classical, gravitational circulation, with riverine outflow at the surface and oceanic inflow close to the bottom. In medium channels, it is about 5 times as strong as in wide (quasi one-dimensional) channels, in which 2SIPS is negligible.

scholarly journals Impact of uncertainties in inorganic chemical rate constants on tropospheric composition and ozone radiative forcing

2017 ◽  
Author(s):  
Ben Newsome ◽  
Mat Evans
Keyword(s):  
Rate Constant ◽  
Atmospheric Chemistry ◽  
Rate Constants ◽  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Transport Model ◽  
Surface Ozone ◽  
Photolysis Rates ◽  
The Impact ◽  
Chemical Rate

Abstract. Chemical rate constants determine the composition of the atmosphere and how this composition has changed over time. They are central to our understanding of climate change and air quality degradation. Atmospheric chemistry models, whether online or offline, box, regional or global use these rate constants. Expert panels synthesise laboratory measurements, making recommendations for the rate constants that should be used. This results in very similar or identical rate constants being used by all models. The inherent uncertainties in these recommendations are, in general, therefore ignored. We explore the impact of these uncertainties on the composition of the troposphere using the GEOS-Chem chemistry transport model. Based on the JPL and IUPAC evaluations we assess 50 mainly inorganic rate constants and 10 photolysis rates, through simulations where we increase the rate of the reactions to the 1σ upper value recommended by the expert panels. We assess the impact on 4 standard metrics: annual mean tropospheric ozone burden, surface ozone and tropospheric OH concentrations, and tropospheric methane lifetime. Uncertainty in the rate constants for NO2 + OH    M →  HNO3, OH + CH4 → CH3O2 + H2O and O3 + NO → NO2 + O2 are the three largest source of uncertainty in these metrics. We investigate two methods of assessing these uncertainties, addition in quadrature and a Monte Carlo approach, and conclude they give similar outcomes. Combining the uncertainties across the 60 reactions, gives overall uncertainties on the annual mean tropospheric ozone burden, surface ozone and tropospheric OH concentrations, and tropospheric methane lifetime of 11, 12, 17 and 17 % respectively. These are larger than the spread between models in recent model inter-comparisons. Remote regions such as the tropics, poles, and upper troposphere are most uncertain. This chemical uncertainty is sufficiently large to suggest that rate constant uncertainty should be considered when model results disagree with measurement. Calculations for the pre-industrial allow a tropospheric ozone radiative forcing to be calculated of 0.412 ± 0.062 Wm−2. This uncertainty (15 %) is comparable to the inter-model spread in ozone radiative forcing found in previous model-model inter-comparison studies where the rate constants used in the models are all identical or very similar. Thus the uncertainty of tropospheric ozone radiative forcing should expanded to include this additional source of uncertainty. These rate constant uncertainties are significant and suggest that refinement of supposedly well known chemical rate constants should be considered alongside other improvements to enhance our understanding of atmospheric processes.

scholarly journals Extending methane profiles from aircraft into the stratosphere for satellite total column validation using the ECMWF C-IFS and TOMCAT/SLIMCAT 3-D model

2017 ◽  
Vol 17 (11) ◽  
pp. 6663-6678 ◽  
Author(s):  
Shreeya Verma ◽  
Julia Marshall ◽  
Mark Parrington ◽  
Anna Agustí-Panareda ◽  
Sebastien Massart ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Transport Model ◽  
A Priori ◽  
Atmospheric Composition ◽  
Random Errors ◽  
Chemical Transport Model ◽  
Spatial Coverage ◽  
Forecasting System ◽  
The Impact ◽  
Total Column

Abstract. Airborne observations of greenhouse gases are a very useful reference for validation of satellite-based column-averaged dry air mole fraction data. However, since the aircraft data are available only up to about 9–13 km altitude, these profiles do not fully represent the depth of the atmosphere observed by satellites and therefore need to be extended synthetically into the stratosphere. In the near future, observations of CO2 and CH4 made from passenger aircraft are expected to be available through the In-Service Aircraft for a Global Observing System (IAGOS) project. In this study, we analyse three different data sources that are available for the stratospheric extension of aircraft profiles by comparing the error introduced by each of them into the total column and provide recommendations regarding the best approach. First, we analyse CH4 fields from two different models of atmospheric composition – the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System for Composition (C-IFS) and the TOMCAT/SLIMCAT 3-D chemical transport model. Secondly, we consider scenarios that simulate the effect of using CH4 climatologies such as those based on balloons or satellite limb soundings. Thirdly, we assess the impact of using a priori profiles used in the satellite retrievals for the stratospheric part of the total column. We find that the models considered in this study have a better estimation of the stratospheric CH4 as compared to the climatology-based data and the satellite a priori profiles. Both the C-IFS and TOMCAT models have a bias of about −9 ppb at the locations where tropospheric vertical profiles will be measured by IAGOS. The C-IFS model, however, has a lower random error (6.5 ppb) than TOMCAT (12.8 ppb). These values are well within the minimum desired accuracy and precision of satellite total column XCH4 retrievals (10 and 34 ppb, respectively). In comparison, the a priori profile from the University of Leicester Greenhouse Gases Observing Satellite (GOSAT) Proxy XCH4 retrieval and climatology-based data introduce larger random errors in the total column, being limited in spatial coverage and temporal variability. Furthermore, we find that the bias in the models varies with latitude and season. Therefore, applying appropriate bias correction to the model fields before using them for profile extension is expected to further decrease the error contributed by the stratospheric part of the profile to the total column.

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