scholarly journals High-resolution induced polarization imaging of biogeochemical carbon-turnover hot spots in a peatland

2021 ◽  
Author(s):  
Timea Katona ◽  
Benjamin Silas Gilfedder ◽  
Sven Frei ◽  
Matthias Bücker ◽  
Adrian Flores-Orozco
Keyword(s):  
Hot Spots ◽  
Electrical Response ◽  
Reaction Rates ◽  
Induced Polarization ◽  
Carbon Turnover ◽  
Iron Sulfides ◽  
Freeze Core ◽  
Imaging Results ◽  
High Concentrations ◽  
Geochemical Analyses

Abstract. Biogeochemical hot spots are defined as areas where biogeochemical processes occur with anomalously high reaction rates relative to their surroundings. Due to their importance in carbon and nutrient cycling, characterization of hot spots is critical to accurately predict carbon budgets in the context of climate change. However, biogeochemical hot spots are difficult to identify in the environment, as sampling resolutions are often too coarse to find these areas in the subsurface. Here, we present imaging results of a geophysical survey using the non-invasive induced polarization (IP) method to identify biogeochemical hot spots of carbon turnover in a minerotrophic wetland. To interpret the field-scale IP signatures, geochemical analyses were performed on freeze-core samples obtained in areas characterized by anomalously high and low IP responses. Our results reveal large variations in the electrical response, with the highest IP phase values (> 20 mrad) corresponding with high concentrations of phosphates (> 4000 μM), an indicator of carbon turnover. Moreover, analysis of the freeze core reveal negligible concentrations of iron sulfides. The extensive geochemical and geophysical data presented in our study demonstrates that IP images can assess changes in the biogeochemical activity in peat, and identify hot spots.

scholarly journals High-resolution induced polarization imaging of biogeochemical carbon turnover hotspots in a peatland

2021 ◽  
Vol 18 (13) ◽  
pp. 4039-4058
Author(s):  
Timea Katona ◽  
Benjamin Silas Gilfedder ◽  
Sven Frei ◽  
Matthias Bücker ◽  
Adrian Flores-Orozco
Keyword(s):  
Electrical Response ◽  
Strong Relationship ◽  
Reaction Rates ◽  
Induced Polarization ◽  
Small Scale ◽  
Carbon Turnover ◽  
Iron Sulfides ◽  
Freeze Core ◽  
Imaging Results ◽  
Biogeochemical Hotspots

Abstract. Biogeochemical hotspots are defined as areas where biogeochemical processes occur with anomalously high reaction rates relative to their surroundings. Due to their importance in carbon and nutrient cycling, the characterization of hotspots is critical for predicting carbon budgets accurately in the context of climate change. However, biogeochemical hotspots are difficult to identify in the environment, as methods for in situ measurements often directly affect the sensitive redox-chemical conditions. Here, we present imaging results of a geophysical survey using the non-invasive induced polarization (IP) method to identify biogeochemical hotspots of carbon turnover in a minerotrophic wetland. To interpret the field-scale IP signatures, geochemical analyses were performed on freeze-core samples obtained in areas characterized by anomalously high and low IP responses. Our results reveal large variations in the electrical response, with the highest IP phase values (> 18 mrad) corresponding to high concentrations of phosphates (> 4000 µM), an indicator of carbon turnover. Furthermore, we found a strong relationship between the electrical properties resolved in IP images and the dissolved organic carbon. Moreover, analysis of the freeze core reveals negligible concentrations of iron sulfides. The extensive geochemical and geophysical data presented in our study demonstrate that IP images can track small-scale changes in the biogeochemical activity in peat and can be used to identify hotspots.

Induced polarization for the spatial characterization of biogeochemical hot spots

2020 ◽  
Author(s):  
Timea Katona ◽  
Jakob Gallistl ◽  
Sven Nordsiek ◽  
Matthias Bücker ◽  
Sven Frei ◽  
...  
Keyword(s):  
Hot Spots ◽  
Iron Concentration ◽  
Reaction Rates ◽  
Induced Polarization ◽  
Ore Deposits ◽  
Imaging Data ◽  
Noninvasive Methods ◽  
Geochemical Composition ◽  
Imaging Results ◽  
Major Interest

<p>Biogeochemical hot spots are spatially confined areas where biogeochemical processes take place with anomalously high reaction rates. On the landscape scale, biogeochemical hot spots are of major interest due to the possible emission of greenhouse gases (carbon dioxide) and high nutrient turnover. Such hot spots are sensitive environments and given their environmental impact, there is a growing demand for noninvasive methods to investigate such hot spots without disturbing the biogeochemical settings. Classical geochemical sampling methods (e.g., piezometers or suction cups) often disturb the redox-sensitive settings by bringing oxygen into anoxic areas. Induced polarization (IP) is a noninvasive geophysical method that was initially developed to explore metal-ore deposits but more recently developed into a versatile tool for environmental studies.  Here, we present imaging results from a geophysical survey using the IP method to characterize hot spots in a wetland located in the Lehstenbach catchment in Southeastern Germany. We collected IP imaging data sets along 64 profiles using 64 electrodes deployed with a spacing of 20 cm. Our highly resolved measurements aimed at delineating hot spots within a thin layer (approximately 20 cm) heterogeneous peat material on top of the local granite bedrock. To validate the field-scale IP signatures, geochemical analyses (e.g., dissolved and solid iron concentration) were performed on freeze-core samples obtained in areas characterized by anomalous high and low IP responses. Furthermore, the thickness of the peat was measured with a dipstick along every fifth profile to evaluate the IP imaging results. Our imaging results reveal an increase in the IP response within the upper 20 cm of the subsurface, which correlates with the variations in the iron concentrations and variations in the geochemical composition of groundwater accompanying microbial activity within the biogeochemical hot spots observed in the soil samples. The IP response decreases in the deeper regions, which can be associated with the granite bedrock.</p>

Determining frequency dependence of carbon turnover in peat using spectral induced polarization

2021 ◽  
Author(s):  
Timea Katona ◽  
Benjamin Gilfedder ◽  
Sven Frei ◽  
Lukas Aigner ◽  
Matthias Bücker ◽  
...  
Keyword(s):  
Frequency Dependence ◽  
Iron Oxides ◽  
Induced Polarization ◽  
Electrode Spacing ◽  
Electrode Polarization ◽  
Biogeochemical Processes ◽  
Carbon Turnover ◽  
Spectral Induced Polarization ◽  
Polarization Response ◽  
Imaging Results

<p>Our study discusses imaging results from a spectral induced polarization (SIP) survey to identify concurring processes (such as aerobic respiration, denitrification, or sulfate- and iron reduction) in a biogeochemically active peat in a wetland located in the Lehstenbach catchment in Southeastern Germany. Terrestrial wetland ecosystems such as peatlands are a critical element in the global carbon cycle. Due to their role as natural carbon sinks and ecological importance for an array of flora and fauna, there is a growing demand to conserve and restore degraded peatlands. Biogeochemical processes occur with non-uniform reaction rates within the peat, making the environment sensitive to physical disturbances. To investigate biogeochemical processes in-situ, it is important to avoid disturbing the redox-sensitive conditions in the subsurface by bringing oxygen into anoxic areas.  Our previous study demonstrated that the induced polarization (IP) was able to identify biogeochemically active and inactive areas of the peat. The IP response was sensitive to the presence of carbon turnover and P release in the absence of iron sulfide. These highly polarizable areas have high iron concentrations, but most likely in an oxidized form. As most iron oxides are poor conductors, the strong polarization response is unlikely related to an electrode polarization process.</p><p>Here we also analyzed the frequency dependence of the SIP data to investigate whether iron oxides and carbon-iron complexes, two possible mechanisms for the high polarization response, can be distinguished. SIP imaging data sets covered the frequency range between 0.06 and 225 Hz and were collected with varying electrode spacing (20 and 50 cm) at different locations within the Waldstein catchment characterized by different properties, e.g., saturated and non-saturated soils. Our imaging results reveal variations of the IP effect within the peat layer, indicating substantial heterogeneities in the peat composition and biogeochemical activity. The frequency dependence allowed us to resolve a sharper contrast between the different features of the peat. Geochemical analyses on a freeze core and pore water samples are used to validate our results and find correlations between the Cole-Cole parameters of the SIP response and the geochemical parameters.</p>

scholarly journals Gold-Bearing Brown Coal Deposits of the Zeya–Bureya Sedimentary Basin (East Russia): Fundamental Model of Formation

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 682
Author(s):  
Anatoliy Petrovich Sorokin ◽  
Andrey Alexeyevich Konyushok ◽  
Valeriy Mikhailovich Kuz’minykh ◽  
Sergey Vadimovich Dugin
Keyword(s):  
Sedimentary Basin ◽  
Complex Compounds ◽  
Inorganic Materials ◽  
Primary Sources ◽  
East Russia ◽  
High Concentrations ◽  
Geochemical Analyses ◽  
Element Transfer ◽  
Bureya Sedimentary Basin ◽  
Gold Bearing

The primary sources and the conditions for the formation of the Paleogene–Neogene coal-bearing deposits in the Zeya–Bureya sedimentary basin were identified and studied with the help of paleogeographic reconstructions and geochemical analyses. Based on the results obtained, we suggest a new basic model of element transfer into the coal, involving two mutually complementary processes to account for the introduction and concentration of gold and other trace elements in the sequences investigated. The first process reflects the system in which peatlands were concentrated along the basin’s junction zone and the passive internal residual mountain ranges. The second reflects the junction’s contrast-type (sharp-type) forms conditions along the external mobile mountain-fold frame. The eroded gold particles were transported over 10–20 km as complex compounds, colloids, dispersed particles, and nanoparticles, and remobilized into clastogenic and dissolved forms along the first few kilometers. The release of gold in the primary sources occurred due to weathering of gold-bearing ore zones, followed by transportation of gold by minor rivers to the areas of peat accumulation. This study considered the probability of the accumulation of high concentrations of gold and rare earth elements (REE) in coal due to the introduction of organic and inorganic materials during floods, with episodes of catastrophic events, and volcano–hydrothermal activities.

Hydrochemistry and carbonate sediment characterisation of Bacalar Lagoon, Mexican Caribbean

2019 ◽  
Vol 70 (3) ◽  
pp. 382 ◽  
Author(s):  
Nidia I. Tobón Velázquez ◽  
Mario Rebolledo Vieyra ◽  
Adina Paytan ◽  
Kyle H. Broach ◽  
Laura M. Hernández Terrones
Keyword(s):  
Trace Elements ◽  
Water Column ◽  
Saturation Index ◽  
Major Elements ◽  
Anthropogenic Sources ◽  
Pollution Indices ◽  
Mexican Caribbean ◽  
High Concentrations ◽  
Geochemical Analyses ◽  
Changes Over Time

The aim of the study is to determine the distribution of trace and major elements in the water and in the sediments of the south part of the Bacalar Lagoon and to identify the sources of the trace elements and their changes over time. The western part of the lagoon water column is characterised by high concentrations of Ca2+, HCO3– and Sr2+, derived from groundwater input. In contrast, the eastern part of the lagoon is characterised by high concentrations of Mg2+, Na+ and Cl–. The lagoon is not affected by present-day seawater intrusion. Water column and sediment geochemical analyses performed in Bacalar Lagoon show clear spatial distribution of different parameters. The saturation index of the water column indicates three main groups: (1) a zone oversaturated with regard to aragonite, calcite and dolomite; (2) an undersaturated area where all three minerals are dissolving; and (3) an area with calcite equilibrium and undersaturation with regard to the other minerals. Herein we present the first measurements of trace element (Ba2+, Mn2+, K+, Ni2+, Zn2+) concentrations in carbonates obtained from sediments in Bacalar Lagoon. In order to evaluate whether the trace elements are derived from natural or anthropogenic sources, four pollution indices were calculated. The results confirmed that Bacalar Lagoon sediments are not contaminated with Ni2+, K+, Mn2+ and Ba2+, and that the Zn2+ seems to have a predominantly anthropogenic origin.

scholarly journals Decay curve analysis for data error quantification in time-domain induced polarization imaging

Geophysics ◽  
2018 ◽  
Vol 83 (2) ◽  
pp. E75-E86 ◽  
Author(s):  
Adrian Flores Orozco ◽  
Jakob Gallistl ◽  
Matthias Bücker ◽  
Kenneth H. Williams
Keyword(s):  
Time Domain ◽  
Decay Curve ◽  
Induced Polarization ◽  
Curve Analysis ◽  
Real Field ◽  
Acquisition Time ◽  
Transfer Resistance ◽  
Imaging Results ◽  
Error Characterization ◽  
Data Error

In recent years, the time-domain induced polarization (TDIP) imaging technique has emerged as a suitable method for the characterization and the monitoring of hydrogeologic and biogeochemical processes. However, one of the major challenges refers to the resolution of the electrical images. Hence, various studies have stressed the importance of data processing, error characterization, and the deployment of adequate inversion schemes. A widely accepted method to assess data error in electrical imaging relies on the analysis of the discrepancy between normal and reciprocal measurements. Nevertheless, the collection of reciprocals doubles the acquisition time and is only viable for a limited subset of commonly used electrode configurations (e.g., dipole-dipole [DD]). To overcome these limitations, we have developed a new methodology to quantify the data error in TDIP imaging, which is entirely based on the analysis of the recorded IP decay curve and does not require recollection of data (e.g., reciprocals). The first two steps of the methodology assess the general characteristics of the decay curves and the spatial consistency of the measurements for the detection and removal of outliers. In the third and fourth steps, we quantify the deviation of the measured decay curves from a smooth model for the estimation of random error of the total chargeability and transfer resistance measurement. The error models and imaging results obtained from this methodology — in the following referred to as “decay curve analysis” — are compared with those obtained following a conventional normal-reciprocal analysis revealing consistent results. We determine the applicability of our methodology with real field data collected at the floodplain scale (approximately 12 ha) using multiple gradient and DD configurations.

Effect of organic compounds on nitrite accumulation during the nitrification process for coking wastewater

2010 ◽  
Vol 62 (9) ◽  
pp. 2096-2105 ◽  
Author(s):  
H. B. Li ◽  
H. B. Cao ◽  
Y. P. Li ◽  
Y. Zhang ◽  
H. R. Liu
Keyword(s):  
Organic Compounds ◽  
Ammonia Oxidation ◽  
Industrial Effluents ◽  
Reaction Rates ◽  
Inhibitory Effect ◽  
Nitrite Accumulation ◽  
Coking Wastewater ◽  
Batch Bioreactor ◽  
The Difference ◽  
High Concentrations

Coking wastewater is one of the most toxic industrial effluents since it contains high concentrations of ammonia and toxic organic compounds. Nitrification might be upset by the inhibitory effect of organic compounds during the biological treatment of the wastewater. In this study, shortcut nitrification was obtained in a sequencing batch bioreactor (SBR) and the inhibitory effect of organic compounds on the nitrification was examined when temperature was 30±1°C, pH was 7.0–8.5, and dissolved oxygen concentration was 2.0–3.0 mg L−1. The inhibitory effect of organic compounds was presumed to be one of the main factors to obtain satisfactory nitrite accumulation. The effect of organic compounds on nitrification was examined in the SBR with initial inhibitor concentrations ranging from 0 to 80 mg L−1, including phenol, pyrocatechol, resorcin, benzene, quinoline, pyridine and indole. The inhibitory effect became stronger with the increase in the concentration, and it was presumed to take place through a direct mechanism resulting from biological toxicity of the inhibitor itself. Furthermore, the inhibitory effect on ammonia oxidation was slighter than that on nitrite oxidation, and the nitrite accumulation ratio during the nitrification was determined by the difference between the reaction rates of above two processes.

Induced‐polarization response of zeolitic conglomerate and carbonaceous siltstone

Geophysics ◽  
1982 ◽  
Vol 47 (1) ◽  
pp. 71-88 ◽  
Author(s):  
P. H. Nelson ◽  
W. H. Hansen ◽  
M. J. Sweeney
Keyword(s):  
Electrical Response ◽  
Induced Polarization ◽  
Phase Response ◽  
Electrical Measurements ◽  
Intimate Contact ◽  
Thin Sections ◽  
Field Surveys ◽  
Core Samples ◽  
Rock Types ◽  
Geologic Materials

Three case studies investigating induced‐polarization (IP) responses of a zeolite‐bearing conglomerate and of two carbonaceous siltstones are presented. The IP response of these noneconomic geologic materials can either mask or mimic the response from sulfide mineralization which is sought by electrical field surveys. The nonsulfide rock types which produced unusually high responses on IP field surveys were sampled by core drilling for chemical, mineralogical, and electrical laboratory study. The electrical response of core samples was measured in a four‐electrode sample holder over the 0.03–1000 Hz range. Geologic description of the core, petrographic examination of thin sections, mineral identification by x‐ray diffraction (XRD), and chemical analysis of samples supplemented the electrical measurements. A surface phase response of 20 mrad was obtained from field surveys over the Gila conglomerate at an Arizona location. Core samples of the Gila were examined in thin section, and clast surfaces were found to be coated with a thin layer of zeolites. These zeolites project into pore spaces in the conglomerate, and thus are in intimate contact with formation waters. A series of laboratory experiments suggests that zeolites cause most of the observed IP response. Phase responses as high as 100 mrad were measured with field surveys over siltstone and limestone sequences in western Nevada. Samples recovered from the Luning and Gabbs‐Sunrise formations include siltstones containing small amounts of amorphous carbon. These siltstones are very conductive electrically, and the high‐phase response is attributed to polarization of the carbon‐pore water interface. Low porosity in these carbonaceous siltstones enhances the phase response.

RESISTIVITY, SELF‐POTENTIAL, AND INDUCED‐POLARIZATION SURVEYS OF A VAPOR‐DOMINATED GEOTHERMAL SYSTEM

Geophysics ◽  
1973 ◽  
Vol 38 (6) ◽  
pp. 1130-1144 ◽  
Author(s):  
A. A. R. Zohdy ◽  
L. A. Anderson ◽  
L. J. P. Muffler
Keyword(s):  
Geothermal Field ◽  
Induced Polarization ◽  
Hot Water ◽  
Thermal Waters ◽  
Geothermal System ◽  
Electrical Soundings ◽  
Lateral Extent ◽  
High Concentrations ◽  
Lake Deposits ◽  
Self Potential

The Mud Volcano area in Yellowstone National Park provides an example of a vapor‐dominated geothermal system. A test well drilled to a depth of about 347 ft penetrated the vapor‐dominated reservoir at a depth of less than 300 ft. Subsequently, 16 vertical electrical soundings (VES) of the Schlumberger type were made along a 3.7‐mile traverse to evaluate the electrical resistivity distribution within this geothermal field. Interpretation of the VES curves by computer modeling indicates that the vapor‐dominated layer has a resistivity of about 75–130 ohm‐m and that its lateral extent is about 1 mile. It is characteristically overlain by a low‐resistivity layer of about 2–6.5 ohm‐m, and it is laterally confined by a layer of about 30 ohm‐m. This 30‐ohm‐m layer, which probably represents hot water circulating in low‐porosity rocks, also underlies most of the survey at an average depth of about 1000 ft. Horizontal resistivity profiles, measured with two electrode spacings of an AMN array, qualitatively corroborate the sounding interpretation. The profiling data delineate the southeast boundary of the geothermal field as a distinct transition from low to high apparent resistivities. The northwest boundary is less distinctly defined because of the presence of thick lake deposits of low resistivities. A broad positive self‐potential anomaly is observed over the geothermal field, and it is interpretable in terms of the circulation of the thermal waters. Induced‐polarization anomalies were obtained at the northwest boundary and near the southeast boundary of the vapor‐dominated field. These anomalies probably are caused by relatively high concentrations of pyrite.

Activated carbon based biological fluidized beds for contaminated water and wastewater treatment: a state-of-the-art review

1994 ◽  
Vol 29 (10-11) ◽  
pp. 309-317 ◽  
Author(s):  
P. M. Sutton ◽  
P. N. Mishra
Keyword(s):  
Activated Carbon ◽  
North America ◽  
Historical Review ◽  
Reaction Rates ◽  
Commercial Application ◽  
Water And Wastewater Treatment ◽  
Active Biomass ◽  
Commercial Media ◽  
Biological Reaction ◽  
High Concentrations

The ability of the biological fluidized bed (BFB) process configuration to intensify biological reaction rates through accumulation of high concentrations of active biomass has brought attention to the technology for the past twenty years. Over 80 commercial, media based BFB reactors have been installed in North America and Europe. Currently there is much interest in systems in which granular activated carbon (GAC) is used as the fluidizing media for treatment of contaminated waters and wastewaters. This paper provides a historical review of the development of the technology together with information on design and commercial application of the technology in North America.

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