Organic Carbon Values Research Articles

Thermal Maturity and Kerogen Type of Badenian Dispersed Organic Matter from the Getic Depression, Romania

The aim of this study is to evaluate the thermal maturity of Upper Badenian (Middle Miocene) petroleum source rocks of the Getic Depression, Romania, and to characterize the dispersed organic matter using organic petrography associated with Rock-Eval pyrolysis. A total of 33 core samples of Upper Badenian source rocks from the central–southern part of Getic Depression was studied. The results show that most samples with values of total organic carbon (TOC) < 1% wt.% have a limited potential of hydrocarbons (HC) generation, and 30% of samples with TOC < 1.82 wt.% and kerogen type III, presenting particularly gas generation potential. In three samples from the Bibești, Grădiște and Socu structures the kerogen type III-II was identified, indicating the capability of oil and gas generation. The Badenian source rocks are thermally immature, as few samples are in the pre-oil window, with values of vitrinite reflectance (VRo%) ranging between 0.41% and 0.55%, and the values of Tmax between 409 °C and 443 °C. Optical microscopy with reflected white light and fluorescence blue light was used for identification of terrigenous macerals (vitrinite, liptinite as, resinite, cutinite, sporinite, and inertinite) associated with marine liptinite macerals (telalginite and lamalginite) showing yellow and bright–yellow epifluorescence.

Prediction of water quality extremes with composite quantile regression neural network.

Water quality extremes, which water quality models often struggle to predict, are a grave concern to water supply facilities. Most existing water quality models use mean error functions to maximize the predictability of water quality mean value. This paper describes a composite quantile regression neural network (CQRNN) model, which simultaneously estimates non-crossing regression quantiles by minimizing the composite quantile regression error function. This method can improve the prediction of extremes. This paper evaluates the performance of CQRNN for predicting extreme values of turbidity and total organic carbon (TOC) and compares with quantile regression (QR), linear regression (LR), and k-nearest neighbors (KNN) in an application to the Hetch Hetchy Regional Water System, which is the primary water supply for San Francisco, CA. CQRNN is superior to QR, LR, and KNN for predicting the mean trend and extremes of turbidity and TOC, especially for the non-Gaussian turbidity data. The performance of CQRNN is the most stable relative to other methods over different training sample sizes.

Factors controlling spatial distribution of complex lithology in transitional shale strata: Implications from logging and 3D seismic data, Shan-2 Lower Sub-member, Eastern Ordos Basin

The Shanxi Formation Shan-2 Lower Sub-member transitional shale in the eastern Ordos Basin is characterized by high total organic carbon value, wide distribution, and large single-layer/cumulative thickness; it is the key target interval for transitional shale gas exploration. Based on drilling, logging, 3D seismic, and natural energy spectrum data, this study discusses the spatial distribution and controlling factors of complex lithology in the transitional shale stratum. Using the multi-lithological eigenvalue method, the lithologic differential distribution characteristics of the Shan-2 Lower Sub-member were identified through seismic attribute analysis and post-stack seismic parameter inversion. On this basis, the controlling factors of lithology spatial difference distribution are revealed by paleogeomorphology restoration, the sedimentary environmental indicator characteristics of shale, and seismic facies division. The results indicate that the lithology distribution of transitional shale strata in the Shan-2 Lower Sub-member is significantly different, and the geomorphological pattern of interjacent depressions and highlands lays a foundation for the formation of the sedimentary system. The environmental and energy differences of paleo-sedimentary water form a sedimentary environment with frequent facies transitions, which controls the distribution of sediments. Th/U and Th/K radios, which indicate redox conditions and sedimentary water energy during the early sedimentary stage of the Shan-2 Lower Sub-member, show that the geomorphic uplift area is characterized by a high-energy transitional environment of mainly developed sandstone and silty mudstone, while the depression is relatively low-energy under a brackish water reduction environment, mainly composed of both dark and carbonaceous shale. During the late sedimentary stage of the Shan-2 Lower Sub-member, when geomorphic control was weakened, it presented a shallow-water, high-energy, and oxidized transitional environment, with a lithology dominated by the complex interbedding of fine-grained sandstone, silty shale, shale, carbonaceous shale, and coal seam. Therefore, it is inferred that the Shan-2 Lower Sub-member may have developed as a barrier island-lagoon sedimentary model. The early depositional period was dominated by barrier island-lagoon-tidal flat depositional combination, thence the sedimentary environment gradually evolved into a tidal flat-swamp environment.

Distribution and Enrichments of Abundant and Trace Elements in Al-Khassa Sub Basin Soil, Kirkuk, Northeastern of Iraq

This study focused on the soil of the Al-Khassa Sub Basin, thirty-four soil samples were collected from different areas of land use and differences in human activity. Physicochemical properties of the soil were examined Hydrogen Potential (pH), Organic Matter (O.M), Loss Of Ignition (L.O.I), Total Organic Carbon (TOC), Cation Exchange Capacity (CEC) and Total Hydrocarbon (THC). Hydrogen Potential (pH) showed that the soil is alkaline above seven with a mean 7.98. Organic Matter (O.M) of the study area with a mean 1.28 % and high value found in Agricultural areas.Cation Exchange Capacity (CEC) with a mean 42.64 (cmol/kg) that is proportional to the granular size of the soil that silty clay. Both Total Organic Carbon (TOC) and Total Hydrocarbon (THC) acceptable concentration values compared to the soils of the arid region. In the present study abundant elements (Calcium (Ca), Silicon (Si), Aluminum (Al), Magnesium (Mg), Sulfur (S), Potassium (K), Chloride (Cl), Titanium (Ti) and Phosphorous (P) ) and Trace element(Chromium (Cr), Manganese (Mn), Nickel (Ni), Zinc (Zn), Vanadium(V), Copper(Cu), Lead(Pb), Arsenic (As), Cobalt (Co), Mercury (Hg) and Molybdenum (Mo)) that have been analyzed in this study and compared with the limits to elements distribution in world soil and local study of Lesser Zab. Elements that are higher than standard Ca, Cl, Cu, As,Hg, Mo, Zn because of excessive use of fertilizers and pesticides and poor irrigation practice and other anthropogenic sources. High concentration elements (Ni, Ca, Co) as a result of the weathering of the parent rocks, it occurs naturally in soils. Other elements that were partially higher than the standard is (K, Cr, P, S, Mg( only in dense agricultural areas. Elements that were lower than Standard (Ti, Al, Si, Mn, V, Pb) represent the unpolluted elements at some locations the sub-basin because they are elements that increase in urban and industrial areas that are not available in the Al-Khassa Sub Basin, main activity and land use of sub basin were rural area and cultivated land. The results of the enrichment factor (EF) and the contamination factor (CF) are calculated for contamination assessment. The Enrichment factor (EF) of the sub-basin is EF 2 depletion to minimal enrichment, indicating no or minimal pollution, but there is a real beginning of contamination of the magnesium element EF 2-5 moderate enrichment, indicating a real beginning of contamination of the magnesium element. indicating of moderate pollution due to the presence of farms that were use of magnesium sulfate fertilizers by villagers at sedan. The results of the Contamination Factor (CF) showed that the region is low to moderate contamination Except for the contamination factor of magnesium in Mam Rash (S22), Belgrad (S10) was very high degree of contamination of Cf > 6, and in Sedan (S25), Gurgay Shammar (S11), and Obarick (S32) was considerable degree of contamination of magnesium 3 < Cf < 6 because of the three villages was agricultural area that use of magnesium fertilizer. Phosphor (P) contamination factor is moderate in Heon (S7), Ali Makaeel (S20) because they are villages that use phosphate fertilizers beside occurrence of poultry farms.

Study of Some Heavy Metals Concentrations from the Soil of Selected Areas at the ‎North Part of Basrah, Iraq

The current study was conducted in the north of Basra to show the state of contamination and how it is affected by different pollutants. including heavy elements and some important environmental indicators of the soil. The study period extended from September 2021 to June 2022 to determine the concentrations of some heavy metals in the soil in (wet-dry) where six elements were estimated, namely zinc, copper, lead, nickel, cadmium, and Iron in the exchangeable phase and the residual phase of the soil Heavy elements have been extracted by standard methods and determined by using an atomic absorption spectrometer, as well as the determination of total carbon organic matter (TOC %) and soil texture. Total organic carbon results are shown in the current study in the soil, where the highest value of total organic carbon (TOC %) was recorded in the dry season in Al-Hawyer region station-1which has a value of 0.480 % and a rate of 0.207 % . The lowest value, was 0.02 % and recorded in the AL-Deer Nillage at station-5, with a rate of 0.183 % but the highest value of carbon in the total organic matter (TOC %) in the wet season was recorded in the Al-Nashwa region (0.615 %) at station with a rate of 0.355 % and the lowest value of 0.125 % was in the Al-Hawyer region station-1, and at a rate of 0.16%. The results of heavy metals for the study area in the soil in the dry season of the exchangeable phase showed that the highest rate of elements (zinc, copper, lead, nickel, cadmium and iron) 60.18, 53.37, 22.95, 57.86, 7.46 and 720 μg/g respectively and the lowest rates recorded were : 20.94, 15.01, 11.96, 23.81, 3.11 and 502.32 μg/g As for the results of heavy elements in the residual phase of the soil (zinc, copper, lead, nickel, cadmium and iron), it recorded the highest rates : 93.24, 20.78, 31.63, 77.82, 9.98 and 751 μg/g where the lowest recorded rates were : 47.29, 8.08, 17.19, 53.28, 9.98 and 550.86 μg/g respectively in the wet season. The heavy weight of the study area in the soil of the exchangeable phase showed that the highest rate of the elements zinc, copper, lead, nickel, cadmium, and iron was: 152.70, 25.35, 20.07, 88.32, 6.73, and 703 μg/g respectively, the lowest recorded rat 17.24, 2.03, 17.10, 20.11, 2.69 and 274 μg/g respectively. The results of heavy metals in the residual phase. The residual zinc element ranged rate between 5.04-41.84 μg/g while the copper element ranged from 0-23.99 μg/g and the lead element ranged from 12.16-24.22 μg/g as for nickel, it ranged between 39.73 and 62.95 μg/g and cadmium ranged from 5.31-10.70 μg/g finally rates of iron elements were also between 504.18 and 721 μg/g.

Geochemical signatures of sedimentary and diagenetic processes in the trace fossil Rosselia from the Pliocene in Taiwan

Trace fossils are structures left in a substrate as the result of the activities of living organisms. The producer of the spindle-shaped trace fossil Rosselia incorporates fine-grained organic rich material into concentric layers surrounding the central shaft. Because Rosselia is common in stressed shallow marine environments where the preservation potential of organic material is generally poor, these trace fossils may act as natural archives, recording changes in the provenance of organic material. Carbon isotope values of organic carbon preserved in laminae of the studied Rosselia typically lie around − 26‰, suggesting a primary terrestrial source. However, increased levels of S and Ca detected from XRF scanning of the laminae indicate that at least some marine material is incorporated. Examination of a diagenetically altered specimen also demonstrates that both elemental composition and δ13C values can be substantially altered diagenesis. Nevertheless, the long stratigraphic range of Rosselia, from the Cambrian to the Present, and its ubiquitous occurrence in stressed shallow-marine settings make it a potentially powerful tool to reconstruct variations in the input of organic material in settings otherwise devoid of fine-grained organic matter.

Tracking sources of PM10 emissions and deposition in the industrial city of Ostrava, Czech Republic: A carbonaceous δ13C-based approach

The sources of airborne particulate matter (PM10) emissions in Ostrava, Czech Republic, were investigated. Emphasis was placed on their organic carbon (OC) and elemental carbon (EC) contents, and their carbon stable isotope composition, δ13C. Emission sources were identified using OC-δ13C and concentration values. To track the extent of long-term deposition, these sources were also identified using the black carbon (BC) δ13C values of soil samples. At all sampling sites, wind flow is predominantly (65–80%) bidirectional in either SW-NE or NE-SW trajectories. Source apportionment along these dominant airflow trajectories was calculated from an isotopic 13C mass balance, and according to differences in the OC content and δ13C values of PM10. Determined emission sources are: (i) combustion of Silesian hard coal (δ13C = −24.5‰); (ii) local Ostrava coal combustion (δ13C = −25.5 to −26‰), automotive emissions (δ13C = −26.5‰), and biogenic particles (δ13C = −28 to −28.5‰). Winter emissions (mean OC concentrations from 12 to 25 μg m−3) originated mostly from coal combustion (80%) in domestic and industrial point sources. Differences were ascribed to automotive emissions. Ostrava is located near the Czech-Polish border, transboundary emissions are transported under a southbound wind flow that transported from 40 to 80% of the collected PM10. Summer emissions were lower (mean OC concentration from 6 to 8 μg m−3). Automotive emissions accounted for up to 40%, whilst biogenic production accounted for 60%. Absence of 13C isotope data of secondary OC (SOC 1.2–1.5 μg m−3) increases uncertainty in our source apportionment in summer; when SOC could comprise >20% of total OC. Contribution of SOC to the winter-measured OC is much lower (5–10%), and has no significant effect on mass balances. The upper soil layer analyses revealed long-term deposition of the same emissions sources. We conclude that the stable δ13C isotope values of OC and EC are useful for discriminating against local sources of PM10 pollution in relatively small urban areas, containing discrete polluting sources. Such a simplified approach can be easily standardized and implemented to manage regulatory compliances in the increasingly commoditized carbon offset market.

Biocrude oil production from a self-settling marine cyanobacterium, Chroococcidiopsis sp., using a biorefinery approach

Although the whole microalgal biomass is typically used as a feedstock for hydrothermal liquefaction (HTL), the conversion of a primary metabolite (i.e., carbohydrate) to biocrude is very low. In this study, a self-settling cyanobacterium (i.e., Chroococcidiopsis sp.) was used to understand the effect of carbohydrate removal, as a pretreatment, on the net energy recovery from the residual biomass. The optimum biocrude yields from pretreated and control biomass were 50.2% (350 °C) and 41.3% (300 °C), respectively. For the temperature range studied, the biocrude yield from the pretreated biomass was higher compared to that obtained from the control feedstock. Further, maximum alkane formation of 42.7 and 23.3% occurred for pretreated and control biomass, respectively, at 325 °C. Total organic carbon and total nitrogen values in the aqueous phase liquid obtained from pretreated biomass were at least 1.31 and 1.23 times lower when compared to the corresponding values obtained from control biomass. When APL was recycled as a source of nutrients, it reduced the biomass yield (24.1%) and pigment content (68.4%) in Chroococcidiopsis sp. Further, a model was developed to understand how the cellular carbohydrate content would affect the net energy recovery for the proposed biorefinery route.

Controls on organic matter accumulation on the Late-Ordovician shales in Awati Sag in northwestern Tarim Basin, NW China

The black shales of the Upper Ordovician Yingan Formation (Fm.) in the northwestern margin of the Tarim Basin was previously considered to be an important source rock. However, the total organic carbon (TOC) values of Yingan black shales was low, averaging 0.51%. Therefore, it remains debated whether they can be served as high-quality source rock. Here, we investigated the sedimentary environment (including terrigenous input, chemical weathering intensity, paleoproductivity, paleoredox conditions) of the Yingan shales and the factors affecting organic matter (OM) enrichment through organic and inorganic geochemical methods. The proxies of terrigenous flux (e.g., Ti/Al and Zr/Al) and sedimentation rate flux [e.g., (La/Yb)P] shows that the terrigenous inputs has no effect on OM enrichment. The low primary productivity (e.g., low values of P/Al, Ba/Al and Ni/Al) of the Yingan shales also exhibits a little effect on OM enrichment. However, the paleoredox proxies (e.g., U/Al, V/Al, U/Th and V/Cr) show that the black shale was deposited in a partial oxidation environment of bottom waters, which is unfavorable for the preservation and enrichment of OM evidenced. The oxidation environment was caused by the enhanced thermohaline circulation and ventilation of bottom waters due to the increasing cooling global climate during Late Ordovician. Therefore, the Yingan shales cannot be served as a source rock or shale gas reservoir. Additionally, the poor OM enrichment model provides new insights for the evaluation of shales linked to cold climatic conditions.

Finding a VOICE in the Southern Hemisphere: A new record of global organic carbon?

Variations in the carbon isotopic composition of carbonate and organic carbon (δ13Ccarb and δ13Corg) are generally used to record perturbations in the global carbon cycle, which are in turn closely linked to changes in climate. However, because of climate gradients on Earth, assignment of the “global” signal in ancient records is not straightforward. Here, we report the δ13C values of organic material in the Upper Jurassic to Lower Cretaceous sedimentary record of the Vaca Muerta Formation, situated in the Neuquén Basin, Argentina, which show similar patterns to those observed in several northern latitude basins. This record of δ13C values in the organic material differs from those measured in the early Atlantic Ocean, a record previously considered to be representative of the global values of organic carbon. As a result of the global synchronicity observed in the δ13C values of organic material from both northern and southern latitudes, we suggest that these patterns may represent the global record of δ13C values in organic material rather than those measured in the proto−Atlantic Ocean. The δ13C values of the organic components show a slight initial decrease of ∼2‰ in the early Tithonian (149−145 Ma) and then another decrease of ∼2‰ before reaching a minimum of −30.29‰ in the late Tithonian (145−143 Ma), followed by a gradual increasing trend throughout the Berriasian (143.1−137.7 Ma). The early Valanginian (137.7−135.5 Ma) was marked by a more substantial increase in δ13C values up to −23.46‰. These changes mirror those seen in Northern Hemisphere locations during the Late Jurassic and Early Cretaceous, where this perturbation has been termed the Volgian isotopic carbon excursion (VOICE). This difference in the Late Jurassic and Early Cretaceous δ13C values between the early Atlantic Ocean and the Neuquén Basin is interpreted to be the result of the climate gradient at the time, which was characterized by more humid conditions in high latitudes compared to dry conditions in the Atlantic Ocean basin.

Downslope variation in hemipelagic sedimentation in an active margin basin: An example from the lower Pleistocene Kiwada and Takamizo formations on the Boso Peninsula, Japan

AbstractHemipelagites are widespread fine‐grained sediments found from shelf margin to deep‐water environments, and they are considered to have been formed as background sedimentation by vertical settling and slow lateral advection of clastic and biogenic fine‐grained particles. Downflow variation in hemipelagic sedimentation, however, is not yet clearly understood, and was investigated in the lower Pleistocene Kiwada and Takamizo formations in the Kazusa forearc basin on the Boso Peninsula, Japan. Mapping of three tephra key beds enabled detailed correlation of two hemipelagite beds over a distance of ca 30 km from shelf‐margin to basin‐plain environments. The sedimentation rates decreased gradually in the downslope direction, but increased locally in response to turbidite sedimentation. This downslope variation indicates that hemipelagic sedimentation is not necessarily constant and varies in response to progradation and retrogradation of deep‐water depositional systems, as well as additional input of fine‐grained sediments from turbidity currents. In contrast, the grain size, magnetic susceptibility, clay‐mineral composition, total organic carbon contents relative to total nitrogen contents (carbon/nitrogen), and δ13C values of organic carbon do not exhibit distinct downslope variation. This downslope consistency indicates that hemipelagites document temporal perturbations of geological and palaeoclimatic conditions in hinterlands, regardless of spatial and temporal variations in deep‐water depositional environments. The concentrations of total organic carbon, total nitrogen and five biomarkers were lower values in turbiditic mudstones and hemipelagites that formed above a turbidite bed than in those of the other hemipelagites. This variation suggests that an additional supply of fine‐grained sediments from turbidity currents likely diluted the organic matter in the hemipelagites. In addition, hemipelagites for which deposition was affected by turbidity currents exhibit slightly lower δ13C values, and may also document an additional contribution of terrestrial organic matter from turbidity currents.

Chemical Fractionations of Lead and Zinc in the Contaminated Soil Amended with the Blended Biochar/Apatite.

Heavy metal contamination in agricultural land is an alarming issue in Vietnam. It is necessary to develop suitable remediation methods for environmental and farming purposes. The present study investigated the effectiveness of using peanut shell-derived biochar to remediate the two heavy metals Zn and Pb in laboratory soil assays following Tessier's sequential extraction procedure. The concentration of heavy metals was analyzed using Inductively coupled plasma mass spectrometry (ICP-MS). This study also compared the effectiveness of the blend of biochar and apatite applied and the mere biochar amendment on the chemical fractions of Pb and Zn in the contaminated agricultural soil. Results have shown that the investigated soil was extremely polluted by Pb (3047.8 mg kg-1) and Zn (2034.3 mg kg-1). In addition, the pH, organic carbon, and electrical conductivity values of amended soil samples increased with the increase in the amendment's ratios. The distribution of heavy metals in soil samples was in the descending order of carbonate fraction (F2) > residue fraction (F5) > exchangeable fraction (F1) > Fe/Mn oxide fraction (F3) > organic fraction (F4) for Pb and F5  ≈  F2 > F1 > F3 > F4 for Zn. The peanut shell-derived biochar produced at 400 °C and 600 °C amended at a 10% ratio (PB4:10 and PB6:10) could significantly reduce the exchangeable fraction Zn from 424.82 mg kg-1 to 277.69 mg kg-1 and 302.89 mg kg-1, respectively, and Pb from 495.77 mg kg-1 to 234.55 mg kg-1 and 275.15 mg kg-1, respectively, and immobilize them in soil. Amending the biochar and apatite combination increased the soil pH, then produced a highly negative charge on the soil surface and facilitated Pb and Zn adsorption. This study shows that the amendment of biochar and biochar blended with apatite could stabilize Pb and Zn fractions, indicating the potential of these amendments to remediate Pb and Zn in contaminated soil.

Distribution Characteristics and Source Apportionment of Winter Carbonaceous Aerosols in a Rural Area in Shandong, China

PM2.5 samples were collected for 15 consecutive days in a rural area in Shandong from January to February 2022. The carbon components and water-soluble ions in PM2.5 were measured, and the distribution characteristics and sources of the carbonaceous aerosols were analysed. It was found that the concentrations of PM2.5 in the region were high in winter (55.79–236.11 μg/m³). Organic carbon (OC) and elemental carbon (EC) accounted for 11.61% and 4.57% of PM2.5, respectively. The average concentrations of OC (19.01 μg/m³) and EC (7.49 μg/m³) in PM2.5 were high. The mean value of secondary organic carbon (SOC), estimated by the minimum R squared (MRS) method, was 14.76 μg/m3, accounting for a high proportion of OC (79.41%). Four OC fractions (OC1, OC2, OC3, and OC4) were significantly correlated with SOC, indicating that the OC components contained a large amount of SOC. OC3, OC4, EC1, and OC2 dominated (accounting for 80% of TC) among the eight carbon fractions. Water-soluble organic carbon (WSOC, 12.82 μg/m³) and methanol-soluble organic carbon (MSOC) (16.28 μg/m³) accounted for 67.47% and 84.99% of OC, respectively, indicating that SOC accounted for a high proportion of OC. The proportion of eight water-soluble ions in PM2.5 was 47.48%. NH4+ can neutralise most of the SO42− and NO3−, forming (NH4)2SO4 and NH4NO3, while Cl− mainly exists in the form of KCl and MgCl2. The ratios of some typical components showed that PM2.5 was not only affected by local combustion sources, but also by mobile sources. The cluster analysis results of the backward trajectory model showed that primary and secondary sources in Shandong Province had a great impact on PM2.5 (64%). The analysis results of the positive matrix factorisation (PMF) model showed that the sources of PM2.5 in the region included mobile sources, primary combustion sources, secondary sources, and dust sources, among which secondary sources contributed the most (60.46%).

Spatial distribution of total mercury and methylmercury in the sediment of a tropical coastal environment subjected to heavy urban inputs

Jurujuba Cove is located in Guanabara Bay (adjacent to highly populated city of Rio de Janeiro, Brazil), which receives diffuse sources of contaminants along with two main freshwater inputs (the Cachoeira and Icaraí rivers), and hosts mussel farms. The main goal of this work was to evaluate the total mercury (THg) and methylmercury (MeHg) concentrations distributions in the sediments of the cove and their associations with physical and chemical parameters, thereby assessing their geochemical behavior. Twenty samples of surface sediments were collected and characterized for grain size, pH, redox potential, organic carbon, total phosphorus, THg and MeHg. Spatial distribution maps were produced for each parameter and a principal components analysis was carried out, to assess THg and MeHg behavior and their relationships with other parameters. The principal components analysis showed that grain size functions as the main diluting agent. The highest THg concentrations were observed in the mussel-farm area (656.1 ng g−1), and were related to fine grain size and elevated organic carbon values. High MeHg concentrations also occurred in the center of the cove, probably favored by high organic carbon content (low-energy environment). Total phosphorus concentrations indicate that Cachoeira River is a possible source of sewage, but little mercury seems to come from it. The results showed that although total mercury concentrations are elevated, with exception of a few locations, small methylmercury convertion rates were recorded in the sediments.

The importance of particularising the model to estimate landfill GHG emissions

Methane generation in landfills can be estimated using mathematical models. One of the most widespread estimation models is that developed by the Intergovernmental Panel on Climate Change (IPCC). Despite its popularity, the simplicity that characterises this model markedly limits the possibility of representing operation alternatives, which can strongly impact surface emissions and hinder the introduction of local data that are sometimes available. In this study, the IPCC model was applied to a case study from which field data on gas emissions were available. To fit the model to the studied landfill conditions, a series of modifications were made, including changes in Degradable Organic Carbon (DOC) and methane generation rate constant (k) values, and degradation times for some waste fractions, and by considering leachate carbon and the inclusion of gas lateral migration phenomena or changes in the methane oxidation factor. The model's Final Version improved the fit of its Initial Version to the experimentally estimated values in the case study by more than 65%. Some modifications, such as considering the carbon dragged by leachate or the contour migration of gas, have a minor impact on the model's fit. However, changes in the degradation time of some fractions according to their particular pretreatment or the modification of parameter k in accordance with the moisture conditions in each landfill phase, strongly influence the model's results. This highlights the importance of particularising estimation models to achieve more accurate results, which allow better estimates of the efficiency of mitigation measures for landfill gas emissions in each facility.

The potential of regenerative agriculture to improve soil health on Gotland, Sweden

AbstractBackgroundRegenerative agriculture has gained attention in mainstream media, academic literature, and international politics in recent years. While many practices and outcomes relate to RA, there is no uniform definition of the term, and only a few comprehensive scientific studies exist of “real‐life” farms and the complexity of what is considered regenerative management and its impact on soil health.AimsThis study aimed to relate the impact of single and various combinations of regenerative management practices to soil health indicators on Gotland, Sweden.MethodsSoil health of 17 farm fields and six gardens was assessed on 11 farms that had applied regenerative agricultural practices for zero to 30 years. We measured a variety of physical (bulk density, infiltration rate, wet aggregate stability, root depth and abundance, penetration resistance), chemical (pH, electric conductivity, C:N ratio, total organic carbon) and biological (earthworm abundance, active carbon, microbial biomass carbon) soil indicators. These parameters were related to regenerative practices (reduced tillage, application of organic matter, livestock integration, crop diversity, and share of legumes and perennials) through a combination of hierarchical clustering, Analysis of Variance and Tukey's tests, principal component analysis, and multiple linear regressions.ResultsAt our study sites, the application of organic matter had a positive impact on bulk density, carbon‐related parameters, wet aggregate stability, and infiltration rate, while reduced tillage and increased share of perennials combined had a positive impact on vegetation density, root abundance and depth, and wet aggregate stability. The field plots were divided into four clusters according to their management, and we found significantly higher values of total organic carbon (*), C:N (*), infiltration rate (**), and earthworm abundance (*) for crop‐high‐org‐input, the management cluster with highest values of organic matter application and no tillage. We found significantly higher values of vegetation density (***) and root abundance (**) for perm‐cover‐livestock, the cluster with no tillage, integration of livestocks, and permanent cover (*** p < 0.001, ** p < 0.01, *p < 0.05, °p < 0.1).ConclusionsWe support existing knowledge on positive impacts of regenerative practices, namely, the addition of organic amendment that improved carbon‐related parameters, as well as the positive effects on soil structure of reduced tillage in combination with an increased share of perennials. We argue for an outcome‐based, and principle‐led concept of regenerative agriculture as a context‐dependent agricultural approach.

Coupling chemical transport modeling and diagnostic ratio analysis for predicting PAH fingerprint in coal tar and creosote contaminated soils

ABSTRACT This article illustrates the use of a fate and transport model and a diagnostic ratio analysis to determine chemical signatures of polyaromatic hydrocarbons (PAHs) in coal tar and creosote residues in soil. The fate and transport model, based on diffusion, convection – advection of PAHs, helps determine their weathering rates in two soil types and provides an insight on the air – soil exchange of PAHs. Time-averaged volatilisation flux, estimated from the model, was used to determine the residual composition of the 16 priority PAH (non-alkylated PAHs) in coal tar and creosote contaminated soils. Expectedly, lower molecular weight (MW) PAHs volatilised faster than higher MW PAHs. In the absence of water movement towards the surface, vapour diffusion is the primary mechanism of transport, and the flux was observed to be high ranging from 8.52–2167.3 x 10−7 kg m−2 day−1. Higher flux was observed for clayey soils. At high values of organic carbon (foc), the flux was observed to be lower due to the binding of PAHs to the soil. The mass flux was higher with water movement (0.6–1036.5 x 10−3 kg m−2 day−1) indicating that diffusion along with wicking were the key mechanisms for PAH losses from soil residues. The modelled volatilisation flux for the PAHs was observed to be within the range of the flux values (for soils and sediment) reported in literature. Double diagnostic ratio analysis was used to compare chemical signatures of the modelled residues to PAH data in actual PAH contaminated soils. The diagnostic PAH ratios of the modelled weathered coal and creosote residues and the actual soil samples correlated well, especially for 5- and 6-ringed PAHs. A good correlation between the modelled and actual diagnostic ratios suggested that the mathematical model can be used to supplement physical sampling and analysis, thereby providing one additional line of evidence for source apportionment.

Study of organic pollution indicators in two stations of the Garmat Ali River, Basra, Iraq

Water is one of the most important natural sources for sustaining life, as human life and various activities depend on it. The current study dealt with knowing the effect of organic pollution on physical and chemical properties in Garmat Ali river, which was represented in two stations, the first station called Al-Mashab, and the second Al-Sindbad. Water and sediment samples were collected monthly during the period from August, 2016 to July, 2017.
 Numbers of physical and chemical variables were measured during this period (water temperature, light penetration, pH, Salinity, dissolved oxygen, biological demand oxygen, chemical demand oxygen, total nitrogen, total phosphorus and total organic carbon in sediment). The results of the study was showed that water temperature were ranged between 13.2-31.3°C for the first station and 13.4-33.1°C for the second station. The light penetration values were ​​ranged between 20.6-58.5 cm for the first station and 35-65 cm for the second station. The pH values were ​​ranged between 7.5-8.6 for the first station and 7.5-8.5 for the second station. Salinity values were ​​ranged between 1.58-3.16 g/l for the first station and 0.92-2.13 g/l for the second station. Dissolved oxygen values were ​​ranged between 4.66-10.8 mg/l for the first station and 11.85-6.26 mg/l for the second station. The values ​​of BOD5 were ​​ranged between 1.1-4.26 mg/l for the first station and 0.75-4.06 mg/l for the station. The values ​​of the COD were ranged between 8-120 mg/l for the first station and 8-61 mg/l for the second station. Total nitrogen values were ​​ranged between 2.8-29.4 mg/l for the first station and 2.4-33.6 mg/l for the second station. The total phosphorus values were ​​ranged between 1.11-19.6 mg/l for the first station and between 1.24-19.98 mg/l for the second station. Total organic carbon values were ​​ranged between 0.36-2.19% for the first station and 0.32-2.94% for the second station. The two stations were recorded a little increased in organic pollution levels during summer months and first station (Al-Mashab) was most affected.

Electronic Control of Traditional Iron-Carbon Electrodes to Regulate the Oxygen Reduction Route to Scale Up Water Purification.

Shifting four-electron (4e-) oxygen reduction in fuel cell technology to a two-electron (2e-) pathway with traditional iron-carbon electrodes is a critical step for hydroxyl radical (HO•) generation. Here, we fabricated iron-carbon aerogels with desired dimensions (e.g., 40 cm × 40 cm) as working electrodes containing atomic Fe sites and Fe3C subnanoclusters. Electron-donating Fe3C provides electrons to FeN4 through long-range activation for achieving the ideal electronic configuration, thereby optimizing the binding energy of the *OOH intermediate. With an iron-carbon aerogel benefiting from finely tuned electronic density, the selectivity of 2e- oxygen reduction increased from 10 to 90%. The resultant electrode exhibited unexpectedly efficient HO• production and fast elimination of organics. Notably, the kinetic constant kM for sulfamethoxazole (SMX) removal is 60 times higher than that in a traditional iron-carbon electrode. A flow-through pilot device with the iron-carbon aerogel (SA-Fe0.4NCA) was built to scale up micropolluted water decontamination. The initial total organic carbon (TOC) value of micropolluted water was 4.02 mg L-1, and it declined and maintained at 2.14 mg L-1, meeting the standards for drinking water quality in China. Meanwhile, the generation of emerging aromatic nitrogenous disinfection byproducts (chlorophenylacetonitriles) declined by 99.2%, satisfying the public safety of domestic water. This work provides guidance for developing electrochemical technologies to satisfy the flexible and economic demand for water purification, especially in water-scarce areas.

A three-part coupled statistical and physical model to monitor water quality parameters governing disinfection byproduct risk at an urban drinking water intake

Extended drought in the twenty-first century has led to loss of volume for lakes and reservoirs across the globe. In the Colorado River Basin, USA, Lakes Powell and Mead have experienced a 68 and 71% decline in volume, respectively, since 2000. Lake Mead is important to the Las Vegas Valley as it accounts for 90–100% of the source water used to serve the 2.2 million residents and 43 million annual tourists. Lake Powell is also vital to maintaining water quality in Lake Mead as it is located upstream and provides 97% of the water entering Mead. As Lakes Powell and Mead are projected to continue decreasing in volume over the next 5 years, it is important to understand the effects of loss of lake volume on water quality in this highly-managed system. Here, the effects of lake drawdown on water quality parameters that affect disinfection byproduct (DBP) formation in the source water for the Las Vegas Valley are projected over the next 5 years using Federal flow projections, regression modeling to project influent temperature from Lake Powell into Lake Mead, and a three-dimensional hydrodynamic and water quality model for Lake Mead. Results from these modeling efforts include projections for changes in values of water temperature, bromide, and total organic carbon (TOC) at the modeled cell that contains the Las Vegas Valley's urban drinking water intake. Raw water bromide was found to have little change across modeled scenarios; however, raw water temperature is projected to increase because of falling lake surface elevations. Raw water TOC is projected to increase three-fold in the simulated scenario that includes the most loss of volume but remains close to historic values in the remaining simulated scenarios. With these raw water quality projections, water managers can better plan for alterations to the water treatment processes, including mitigation of DBP formation.