Impact of sampling techniques on the concentration of ammonia and sulfide in pore water of marine sediments

2019 ◽  
Vol 48 (2) ◽  
pp. 184-195 ◽  
Author(s):  
Aleksandra Brodecka-Goluch ◽  
Patrycja Siudek ◽  
Jerzy Bolałek
Keyword(s):  
Pore Water ◽  
Sediment Cores ◽  
Ex Situ ◽  
Water Sampling ◽  
Air Filtration ◽  
Pore Waters ◽  
Atmospheric Air ◽  
Water Constituents ◽  
Sampling Procedures ◽  
The Impact

Abstract Three ex situ pore water sampling procedures (I – rhizon samplers, II – centrifugation of sediment subsamples collected from different sediment depths without core sectioning, III – core sectioning and centrifugation of sediment sections) were compared to indicate factors that may affect concentrations of pore water constituents (ammonia and sulfides). The methods were selected and modified in such a way as to determine how the concentrations are affected by different factors related to sampling procedures, e.g. contact with atmospheric air, filtration and sediment core disturbance. They were tested on nine sediment cores collected at one site in the southern Baltic Sea. The concentration of ammonia in pore water from centrifuged sediment sections was significantly higher compared to pore water extracted by rhizons – probably due to the impact of changing pH. The factor with the greatest impact on the H2S/HS– concentration in the analyzed pore water was the contact with atmospheric air and/or the extrusion of sediments from a core liner. Rhizons proved to be the best option for sampling pore waters analyzed for H2S/HS– and NH4+/NH3. In the case of H2S/HS– we noticed the smallest loss of the analyzed constituents. For ammonia, the centrifugation of the whole sediment sections was likely to cause interferences in the indophenol blue method.

scholarly journals Thermokarst Lagoons: A Core-Based Assessment of Depositional Characteristics and an Estimate of Carbon Pools on the Bykovsky Peninsula

2021 ◽  
Vol 9 ◽  
Author(s):  
Maren Jenrich ◽  
Michael Angelopoulos ◽  
Guido Grosse ◽  
Pier Paul Overduin ◽  
Lutz Schirrmeister ◽  
...  
Keyword(s):  
Pore Water ◽  
Sediment Cores ◽  
The Arctic ◽  
Middle Pleistocene ◽  
Carbon Pools ◽  
Permafrost Region ◽  
Depositional History ◽  
Terrestrial Carbon Cycle ◽  
Lake Drainage ◽  
The Impact

Permafrost region subsurface organic carbon (OC) pools are a major component of the terrestrial carbon cycle and vulnerable to a warming climate. Thermokarst lagoons are an important transition stage with complex depositional histories during which permafrost and lacustrine carbon pools are transformed along eroding Arctic coasts. The effects of temperature and salinity changes during thermokarst lake to lagoon transitions on thaw history and lagoon deposits are understudied. We analyzed two 30-m-long sediment cores from two thermokarst lagoons on the Bykovsky Peninsula, Northeast Siberia, using sedimentological, geochronological, hydrochemical, and biogeochemical techniques. Using remote sensing we distinguished between a semi-closed and a nearly closed lagoon. We (1) characterized the depositional history, (2) studied the impact of marine inundation on ice-bearing permafrost and taliks, and (3) quantified the OC pools for different stages of thermokarst lagoons. Fluvial and former Yedoma deposits were found at depth between 30 and 8.5 m, while lake and lagoon deposits formed the upper layers. The electrical conductivity of the pore water indicated hypersaline conditions for the semi-closed lagoon (max: 108 mS/cm), while fresh to brackish conditions were observed beneath a 5 m-thick surface saline layer at the nearly closed lagoon. The deposits had a mean OC content of 15 ± 2 kg/m3, with higher values in the semi-closed lagoon. Based on the cores we estimated a total OC pool of 5.7 Mt-C for the first 30 m of sediment below five mapped lagoons on the Bykovsky Peninsula. Our results suggest that paleo river branches shaped the middle Pleistocene landscape followed by late Pleistocene Yedoma permafrost accumulation and early Holocene lake development. Afterward, lake drainage, marine flooding, and bedfast ice formation caused the saline enrichment of pore water, which led to cryotic talik development. We find that the OC-pool of Arctic lagoons may comprise a substantial inventory of partially thawed and partially refrozen OC, which is available for microbial degradation processes at the Arctic terrestrial-marine interface. Climate change in the Arctic leading to sea level rise, permafrost thaw, coastal erosion, and sea ice loss may increase the rate of thermokarst lagoon formation and thus increase the importance of lagoons as biogeochemical processors of former permafrost OC.

scholarly journals The Impact of Methane Seepage on the Pore-Water Geochemistry across the East Siberian Arctic Shelf

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 397
Author(s):  
Natalia Guseva ◽  
Yulia Moiseeva ◽  
Darya Purgina ◽  
Elena Gershelis ◽  
Evgeniy Yakushev ◽  
...  
Keyword(s):  
Pore Water ◽  
World Ocean ◽  
Arctic Shelf ◽  
Anaerobic Oxidation Of Methane ◽  
Atmospheric Methane ◽  
Pore Waters ◽  
Geochemical Environment ◽  
Methane Seepage ◽  
Siberian Arctic ◽  
The Impact

East Siberian Arctic Shelf, the widest and the shallowest shelf of the World Ocean, covering greater than two million square kilometers, has recently been shown to be a significant modern source of atmospheric methane (CH4). The CH4 emitted to the water column could result from modern methanogenesis processes and/or could originate from seabed deposits (pre-formed CH4 preserved as free gas and/or gas hydrates). This paper focuses primarily on understanding the source and transformation of geofluid in the methane seepage areas using ions/trace elements and element ratios in the sediment pore-water. Six piston cores and totally 42 pore-water samples were collected in the East Siberian Sea and the Laptev Sea at water depths ranging from 22 to 68 m. In the active zones of methane release, concentrations of vanadium, thorium, phosphorus, aluminum are increased, while concentrations of cobalt, iron, manganese, uranium, molybdenum, copper are generally low. The behavior of these elements is determined by biogeochemical processes occurring in the pore-waters at the methane seeps sites (sulfate reduction, anaerobic oxidation of methane, secondary precipitation of carbonates and sulfides). These processes affect the geochemical environment and, consequently, the species of these elements within the pore-waters and the processes of their redistribution in the corresponding water–rock system.

Biogeochemical cycling of nutrients and trace metals in anoxic freshwater sediments of the Neckar River, Germany

1995 ◽  
Vol 46 (1) ◽  
pp. 237 ◽  
Author(s):  
Y Song ◽  
G Muller
Keyword(s):  
Organic Matter ◽  
Trace Metals ◽  
Pore Water ◽  
Sediment Cores ◽  
Sharp Decrease ◽  
Metal Sulfides ◽  
Pore Waters ◽  
Overlying Water ◽  
Mineralization Of Organic Matter ◽  
Cycling Of Nutrients

Pore-water components (SO42-, Fe2+, Mn2+), including nutrients (NH4+:, NO3-, PO43-), alkalinity and pH were determined at three sites in the Neckar River. Sequential extraction procedures and trace metals in both pore waters and sediments are reported in order to evaluate the mobility of trace metals in contaminated sediments. The results show that the mineralization of organic matter plays an important role in the cycling of nutrients and trace metals. Pore-water profiles (Zn, Cu, Pb, Cd) suggest that the element maximums at the sediment-water interface are caused by the decomposition of biomass. Low concentrations of dissolved Zn, Cu, Pb and Cd in the anoxic sediments can be explained by a sharp decrease of SO42- in pore water concomitant with HS- production. This leads to the formation of highly insoluble metal sulfides. Solubility calculations show that the sediments act as a sink for trace metals with respect to trace metal sulfides. The organic/sulfidic-bound fraction accounts for 64-81% of Cd in the sediment cores, 36-67% of Pb and 51-69% of Cu. In contrast, Cr in pore water increases with depth because of its release from Fe/Mn oxides. NH4+ and PO43- are also released into the pore water owing to the mineralization of organic matter. No significant fluxes of NH4+ and PO43- into overlying water were found because of the existence of an oxic surface layer.

scholarly journals The Impact of Ex Situ Heart Perfusion in Pediatric Transplantation: An Analysis of the UNOS Registry

2021 ◽  
Vol 40 (4) ◽  
pp. S39
Author(s):  
J. Conway ◽  
Y. Hong ◽  
T. Pidborochynski ◽  
M. Khan ◽  
D.H. Freed
Keyword(s):  
Ex Situ ◽  
Pediatric Transplantation ◽  
Heart Perfusion ◽  
The Impact

scholarly journals Minimization of the Line Resistance Impact on Memdiode-Based Simulations of Multilayer Perceptron Arrays Applied to Pattern Recognition

2021 ◽  
Vol 11 (1) ◽  
pp. 9
Author(s):  
Fernando Leonel Aguirre ◽  
Nicolás M. Gomez ◽  
Sebastián Matías Pazos ◽  
Félix Palumbo ◽  
Jordi Suñé ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Ex Situ ◽  
Multilayer Perceptrons ◽  
Spice Simulation ◽  
Large Dataset ◽  
High Line ◽  
Calibration Algorithm ◽  
The Impact ◽  
Line Resistance

In this paper, we extend the application of the Quasi-Static Memdiode model to the realistic SPICE simulation of memristor-based single (SLPs) and multilayer perceptrons (MLPs) intended for large dataset pattern recognition. By considering ex-situ training and the classification of the hand-written characters of the MNIST database, we evaluate the degradation of the inference accuracy due to the interconnection resistances for MLPs involving up to three hidden neural layers. Two approaches to reduce the impact of the line resistance are considered and implemented in our simulations, they are the inclusion of an iterative calibration algorithm and the partitioning of the synaptic layers into smaller blocks. The obtained results indicate that MLPs are more sensitive to the line resistance effect than SLPs and that partitioning is the most effective way to minimize the impact of high line resistance values.

scholarly journals Hydrochemistry of sediment pore water in the Bratsk reservoir (Baikal region, Russia)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
V. I. Poletaeva ◽  
E. N. Tirskikh ◽  
M. V. Pastukhov
Keyword(s):  
Pore Water ◽  
Ionic Composition ◽  
Water System ◽  
Water Reservoir ◽  
Environmental Parameters ◽  
Water Area ◽  
Pore Waters ◽  
Overlying Water ◽  
Major Ion ◽  
Bratsk Reservoir

AbstractThis study aimed to identify the factors responsible for the major ion composition of pore water from the bottom sediments of the Bratsk water reservoir, which is part of the largest freshwater Baikal-Angara water system. In the Bratsk reservoir, the overlying water was characterized as HCO3–Ca–Mg type with the mineralization ranging between 101.2 and 127.7 mg L−1 and pore water was characterized as HCO3–SO4–Ca, SO4–Cl–Ca–Mg and mixed water types, which had mineralization varying from 165.9 to 4608.1 mg L−1. The ionic composition of pore waters varied both along the sediment depth profile and across the water area. In pore water, the difference between the highest and lowest values was remarkably large: 5.1 times for K+, 13 times for Mg2+, 16 times for HCO3−, 20 times for Ca2+, 23 times for Na+, 80 times for SO42−, 105 times for Cl−. Such variability at different sites of the reservoir was due to the interrelation between major ion concentrations in the pore water and environmental parameters. The major factor responsible for pore water chemistry was the dissolution of sediment-forming material coming from various geochemical provinces. In the south part of the reservoir, Cl−, Na+ and SO42− concentrations may significantly increase in pore water due to the effect of subaqueous flow of highly mineralized groundwater.

scholarly journals Phosphorous Supply to a Eutrophic Artificial Lake: Sedimentary versus Groundwater Sources

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 563
Author(s):  
Wiebe Förster ◽  
Jan C. Scholten ◽  
Michael Schubert ◽  
Kay Knoeller ◽  
Nikolaus Classen ◽  
...  
Keyword(s):  
Water Quality ◽  
Stable Isotope ◽  
Pore Water ◽  
Lake Water ◽  
Sediment Cores ◽  
Eutrophic Lake ◽  
Stable Water Isotopes ◽  
Artificial Lake ◽  
Sediment Pore Water ◽  
Mass Balance Models

The eutrophic Lake Eichbaumsee, a ~1 km long and 280 m wide (maximum water depth 16 m) dredging lake southeast of Hamburg (Germany), has been treated for water quality improvements using various techniques (i.e., aeration plants, removal of dissolved phosphorous by aluminum phosphorous precipitation, and by Bentophos® (Phoslock Environmental Technologies, Sydney, Australia), adsorption) during the past ~15 years. Despite these treatments, no long-term improvement of the water quality has been observed and the lake water phosphorous content has continued to increase by e.g., ~670 kg phosphorous between autumn 2014 and autumn 2019. As no creeks or rivers drain into the lake and hydrological groundwater models do not suggest any major groundwater discharge into the lake, sources of phosphorous (and other nutrients) are unknown. We investigated the phosphorous fluxes from sediment pore water and from groundwater in the water body of the lake. Sediment pore water was extracted from sediment cores recovered by divers in August 2018 and February 2019. Diffusive phosphorous fluxes from pore water were calculated based on phosphorus gradients. Stable water isotopes (δ2H, δ18O) were measured in the lake water, in interstitial waters in the banks surrounding the lake, in the Elbe River, and in three groundwater wells close to the lake. Stable isotope (δ2H, δ18O) water mass balance models were used to compute water inflow/outflow to/from the lake. Our results revealed pore-water borne phosphorous fluxes between 0.2 mg/m2/d and 1.9 mg/m2/d. Assuming that the measured phosphorous fluxes are temporarily and spatially representative for the whole lake, about 11 kg/a to 110 kg/a of phosphorous is released from sediments. This amount is lower than the observed lake water phosphorous increase of ~344 kg between April 2018 and November 2018. Water stable isotope (δ2H, δ18O) compositions indicate a water exchange between an aquifer and the lake water. Based on stable isotope mass balances we estimated an inflow of phosphorous from the aquifer to the lake of between ~150 kg/a and ~390 kg/a. This result suggests that groundwater-borne phosphorous is a significant phosphorous source for the Eichbaumsee and highlights the importance of groundwater for lake water phosphorous balances.

scholarly journals Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray Tomography

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 389
Author(s):  
German Dario Martinez-Carvajal ◽  
Laurent Oxarango ◽  
Jérôme Adrien ◽  
Pascal Molle ◽  
Nicolas Forquet
Keyword(s):  
Porous Media ◽  
Structural Changes ◽  
Rest Period ◽  
Treatment Wetlands ◽  
Ex Situ ◽  
Initial Value ◽  
Treatment Wetland ◽  
X Ray ◽  
The Impact ◽  
Deposit Layer

Clogging constitutes a major operational issue for treatment wetlands. The rest period is a key feature of French Vertical Flow (VF) treatment wetlands and serves to mitigate clogging. An ex-situ drying experiment was performed to mimic the rest period and record structural changes in the porous media using X-ray Computed Tomography (CT). Samples containing the deposit and gravel layers of a first stage French VF treatment wetland were extracted and left to dry in a control environment. Based on CT scans, three phases were identified (voids, biosolids, and gravels). The impact of the rest period was assessed by means of different pore-scale variables. Ultimately, the volume of biosolids had reduced to 58% of its initial value, the deposit layer thickness dropped to 68% of its initial value, and the void/biosolid specific surface area ratio increased from a minimum value of 1.1 to a maximum of 4.2. Cracks greater than 3 mm developed at the uppermost part of the deposit layer, while, in the gravel layer, the rise in void volume corresponds to pores smaller than 2 mm in diameter. Lastly, the air-filled microporosity is estimated to have increased by 0.11 v/v.

scholarly journals Viability Assessment in Liver Transplantation—What Is the Impact of Dynamic Organ Preservation?

Biomedicines ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 161
Author(s):  
Rebecca Panconesi ◽  
Mauricio Flores Carvalho ◽  
Matteo Mueller ◽  
David Meierhofer ◽  
Philipp Dutkowski ◽  
...  
Keyword(s):  
Liver Function ◽  
Organ Preservation ◽  
Ex Situ ◽  
Current Status ◽  
Intensive Care Treatment ◽  
Viability Assessment ◽  
Great Opportunity ◽  
Continuous Increase ◽  
Diagnostic Time ◽  
The Impact

Based on the continuous increase of donor risk, with a majority of organs classified as marginal, quality assessment and prediction of liver function is of utmost importance. This is also caused by the notoriously lack of effective replacement of a failing liver by a device or intensive care treatment. While various parameters of liver function and injury are well-known from clinical practice, the majority of specific tests require prolonged diagnostic time and are more difficult to assess ex situ. In addition, viability assessment of procured organs needs time, because the development of the full picture of cellular injury and the initiation of repair processes depends on metabolic active tissue and reoxygenation with full blood over several hours or days. Measuring injury during cold storage preservation is therefore unlikely to predict the viability after transplantation. In contrast, dynamic organ preservation strategies offer a great opportunity to assess organs before implantation through analysis of recirculating perfusates, bile and perfused liver tissue. Accordingly, several parameters targeting hepatocyte or cholangiocyte function or metabolism have been recently suggested as potential viability tests before organ transplantation. We summarize here a current status of respective machine perfusion tests, and report their clinical relevance.

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