High Total Organic Carbon Research Articles

Climate plays a dominant role over land management in governing soil carbon dynamics in North Western Himalayas

The soil carbon (C) dynamics is strongly influenced by climate and land-use patterns in the Himalayas. Therefore, soils under five prominent land use [e.g., maize (Zea mays), horticulture, natural forest, grassland, and wasteland] were sampled down up to 30 cm depth under two climatic conditions viz., temperate and subtropical to assess the impacts of climate and landuse on soil C dynamics. Results demonstrated that irrespective of land use, temperate soil contains 30.66% higher C than subtropical soils. Temperate soils under natural forests had the higher total organic carbon (TOC, 21.90 g kg−1), Walkley-Black carbon (WBC, 16.42 g kg−1), contents, and stocks (TOC, 66.92 Mg ha−1 and WBC, 50.24 Mg ha−1), and total soil organic matter (TSOM, 3.78%) concentration as compared to other land uses like maize, horticulture, grassland, and wasteland. Under both climatic conditions, maize land use had the lowest TOC 9.63, 6.55 g kg−1 and WBC 7.22, 4.91 g kg−1 at 0–15 and 15–30 cm soil depth, respectively. Horticulture land use had 62.58 and 62.61% higher TOC and WBC over maize-based land use under subtropical and temperate climatic conditions at 0–30 cm soil depth, respectively. However, soils of maize land use under temperate conditions had ∼2 times more TOC than in subtropical conditions. The study inferred that the C-losses is more in the subtropical soil than in temperate soils. Hence, the subtropical region needs more rigorous adoption of C conservation farming practices than the temperate climatic setting. Although, the adoption of C storing and conserving practices is crucial under both climatic settings to arrest land degradation. Horticultural land uses along with conservation effective soil management practices may be encouraged to restore more soil C and to improve the livelihood security of the hill populace in the North Western Himalayas.

Carbon stability and morphotype composition of biochars from feedstocks in the Mekong Delta, Vietnam

This study investigates carbon stability of biochars produced from wood, herbaceous, and fruit agricultural waste products from southern Vietnam. The biochars were produced by pyrolysis to 500 °C, 700 °C, and 900 °C at a heating rate of 10 °C/min. Organic geochemistry and petrology have well-established measurable parameters that define degree of preservation of organic carbon in the Earth's crust. These parameters are utilized, comparatively, to infer the organic carbon stability in biochars relative to that preserved in the geological carbonaceous rocks. The stability of carbon was assessed by measuring incident-light random reflectance (%Ro) to determine the degree of thermally induced aromatization/ordering of the biochar carbon molecules. Additionally, the organic carbon content of the biochars was quantitatively separated into reactive and non-reactive carbon fractions based on thermodynamic stability of CH and CO bonds. The results show increasing carbon stability with increasing pyrolysis temperature and indicate high stability has been achieved at 700 °C and 900 °C where the biochars have the highest total organic carbon (TOC) contents and lowest Hydrogen Index values. Occurrence of a small quantity of readily degradable, labile free hydrocarbons (soluble organic matter; SOM) is due to condensation of the thermally generated hydrocarbons on the surfaces of the biochars. This fraction is minimized in the biochars produced at 700 °C and 900 °C due to volatilization of the free hydrocarbons at higher pyrolysis temperatures. The relatively substantial content of labile hydrocarbons associated with particulate organic matter (POM) in the 500 °C produced biochars is attributed to the incomplete pyrolyzation of the feedstock at this temperature. This fraction declines to near zero at 700 °C and 900 °C as complete carbonization is achieved at these higher temperatures. The overall carbon budget within the biochar shows that irrespective of the biochar type, over 97% of the TOC consists of highly refractory, residual carbon that geochemically is considered to possess long-term stability (“inert”). This is further underpinned by a pronounced increase in biochar mean random reflectance from <2.33% at 500 °C to >4.35% when pyrolyzed at 700 °C, indicating a highly polyaromatized condensed carbon structure. Rice husk is an exception as it yields a mean reflectance of 4.55% at 500 °C suggesting that pyrolysis temperature is not the only factor controlling %Ro and hence carbon stability. Furthermore, the biochar compositions show a relationship between feedstock and pyrolysis temperature. The biochar morphotype composition changes significantly with increasing temperature, but the analyzed biochars are all dominated by fusinoid/solid (primarily fusinoid) morphotypes with the highest initial quantity recorded at 500 °C. This quantity decreases with increasing pyrolysis temperature while porous morphotypes (tenuinetwork, crassinetwork, mixed porous, mixed dense) increase. Variations in morphotype composition observed between the biochars is attributed to the structural nature of the feedstocks.

Pore Fractal Characteristics of Lacustrine Shale of Upper Cretaceous Nenjiang Formation from the Songliao Basin, NE China

The evaluation of pore characteristics in lacustrine shales is of significance for shale oil and gas exploration in terrestrial sedimentary basins. However, due to the complex depositional environments, there have been few reports on the quantitative evaluation of lacustrine pores. In this study, we carry out experiments, e.g., scanning electron microscopy (SEM), nitrogen adsorption, X-ray diffraction (XRD), and rock pyrolysis, on sixteen lacustrine shale core samples of the Late Cretaceous Nenjiang Formation (K2n1+2) in the Songliao Basin. At the same time, we bring in the fractal dimensions to quantitatively characterize the pores of shale samples in K2n1+2. The kerogen type of shales in the Nenjiang Formation is mainly type Ⅰ. The shales of K2n1+2 develop a large number of mineral intergranular pores and a small number of organic pores and mineral intragranular pores. The primary minerals of the samples are clay minerals and quartz. The total organic carbon (TOC) has a correlation with the pore physical parameters, whereas the content of minerals does not correlate significantly with pore development. The average pore fractal dimensions obtained from the analysis of nitrogen adsorption data are D1 = 2.5308 and D2 = 2.6557. There is a significant negative correlation between the fractal dimensions (D1 and D2) and the TOC content: the lower the fractal dimensions, the higher the TOC, and the more the free oil. In low maturity shales with higher TOC content, due to hydrocarbon generation, larger pores with a regular shape (small fractal parameters) can be produced, which can store more free oil. The shale reservoir evaluation of K2n1+2 in the Songliao Basin should be focused on shales with higher TOC and lower pore fractal parameters. Our work provides a reference for the shale oil evaluation of K2n1+2 in the Songliao Basin and complements studies on lacustrine pore characteristics.

Metal-free electro-Fenton degradation of perfluorooctanoic acid with efficient ordered mesoporous carbon catalyst

Heterogeneous electro-Fenton with in situ generated H2O2 and •OH is a cost-effective method for the degradation of refractory organic pollutants, in which the catalyst is an important factor affecting its degradation performance. Metal-free catalysts can avoid the potential risk of metal dissolution. However, it remains great challenge to develop efficient metal-free catalyst for electro-Fenton. Herein, ordered mesoporous carbon (OMC) was designed as a bifunctional catalyst for efficient H2O2 and •OH generation in electro-Fenton. The electro-Fenton system showed fast perfluorooctanoic acid (PFOA) degradation with kinetics constant of 1.26 h−1 and high total organic carbon (TOC) removal efficiency of 84.0 % after 3 h reaction. The •OH was the main species responsible for PFOA degradation. Its generation was promoted by the abundant oxygen functional groups such as C-O-C and the nano-confinement effect of mesoporous channels on OMCs. This study indicated that OMC is an efficient catalyst for metal-free electro-Fenton system.

Geochemical conditions regulating chromium preservation in marine sediments

In the marine sediment record, concentrations and isotope ratios of chromium (Cr) can be used to reconstruct ocean biogeochemical conditions. These reconstructions rely on a detailed understanding of the chemical pathways that Cr undergoes as it is transferred from the water column to the sediment record. We examined Cr concentrations in marine pore fluids and sediments from six continental margin sites, which can be grouped into two basic environments: (1) sites where sediments are oxygenated and rich in solid phase Mn (herein termed oxic), and (2) sites where sediments are organic C (Corg)-rich and oxygen is depleted (anoxic). We found Cr concentrations to be lower (maximum of 12 nM in pore fluids and 124 ppm sediment solid phase) at oxic sites compared with anoxic sites (maximum of 77 nM and 184 ppm). Our findings confirm previously published interpretations of dissolved Cr in pore fluids (Brumsack and Gieskes, 1983; Shaw et al., 1990). In oxic surface sediments, particulate Cr(III) can be oxidised by Mn oxides, which leads to elevated concentrations of dissolved Cr co-occurring at the same depth as elevated Mn concentrations in the sediment. Under these oxidising conditions, down-core sediments contain relatively low solid-phase Cr concentrations. In oxic sediments, Cr speciation reveals that most of the pore fluid Cr is in the Cr(VI) state. At the site where Mn oxide-rich sediments rest below an oxic water column, oxidative loss of Cr from the sediment to the bottom water leads to the lowest estimated Cr burial efficiency of the sites examined here. Under anoxic Corg-rich conditions, both pore fluids and sediment solid phases contain high Cr concentrations, with 40–80% of dissolved pore fluid Cr present as Cr(III). This enrichment of Cr appears to be tightly linked to the presence of high total organic carbon (TOC) content and scavenging of Cr by (organic) particles in the water column. Combined, these data highlight the strong dependence of Cr on both sedimentary redox conditions as well as biological productivity. Based on the data from modern continental margin sediments, we propose that Cr concentrations and isotope compositions of the authigenic sediment fraction may record a combination of redox conditions and biological productivity in the water column. If confirmed by Cr isotope analyses, these findings will add support for the notion that Cr may serve as a proxy for ocean biological and chemical sedimentological conditions. Thus, careful assessment of the impact of organic matter on Cr is required for reconstructions of redox conditions with sedimentary records.

Foraminifera dissolution phases in the upper cretaceous succession of Jebel Duwi, Egypt

The present work examines the function of differential dissolution in planktic and benthic foraminifera and introduces the major factors that affect dissolution in early Mid-Maastrichtian Event MME and Late Maastrichtian Event LME paleoenvironmental reconstructions. Two observations on foraminifera dissolution in the Dakhla Formation, where planktic foraminifera are more susceptible to dissolution than benthic foraminifera in the Hamama Member of the Jebel Duwi section, Eastern Desert (Egypt). They are characterized by a decline in the planktic/benthic (P/B) ratio and a rise in the agglutinated percentage. The results of those observations are used for revealing foraminiferal dissolution in these two zones (Racemiguembelina fructicosa CF4a and Pseudoguembelina palpebra CF2). During these two zones, there were excessive relative abundances of agglutinated foraminifera, indicating that these two intervals witnessed severe carbonate dissolution. The high total organic carbon (TOC) and low pH due to the presence of a lot of organic matter in the black shale’s of the Dakhla Formation of the upper Maastrichtian age is the explanation for the observed dissolution that has nothing to do with oceanographic or volcanic processes. The presence of pyrite within the black shale interval suggests low oxygen conditions and the potential for meteoric water to react with the pyrite and form sulfuric acid. This acid could dissolve any carbonate material well after the original deposition.

Variation in soil organic carbon content and its dynamics under different cropping sequences and nutrient management practices in middle indo-gangetic plains

In the era when the population is escalating at a rapid rate while on other hand the land for cultivation is declining, there is tremendous pressure in high fertile lands like the Indo-Gangetic plains to produce food grains with intensified cropping. This intensification of agriculture has lead to stagnation of yield in cropping systems due to decline in soil organic matter and nutrient cycling. Soil organic carbon along with the microbial biomass are important indicators of physical, chemical as well as biological properties. This two parameters can be determined by various methods like dehydrogenase activity, soil respiration rate and microbial biomass calculation by chloroform and irradiation method. The current paper comprises of the study of different cropping systems in the Indo Gangetic plains in order to analyze its different organic carbon pool, relationship between them and different land use system that influences them. It was noticed that the system receiving both organic and inorganic fertilizers had higher total organic carbon, higher respiration rate, labile carbon along with higher microbial population. Under the nutrient management consisting of FYM + NPK fertilizer treatment there was increasing microbial biomass carbon and total organic carbon over other treatments because of more or higher root biomass. Therefore for a healthy soil and sustainable production system in high fertile and demand area of Indo Gangetic plain it is necessary to assess the soil organic carbon pools and maintain them by using integrated nutrient management.

Lithofacies Characteristics and Their Effects on Shale Oil Enrichment: A Case Study from Shahejie Formation of the Qibei Sag, Bohai Bay Basin, China

The lithology and lithofacies assemblage of shale are highly complex and heterogeneous in the continental shale formations due to rapid changes in the sedimentary environment and source material, complicating the evaluation of shale oil enrichment areas, such as the member 3 of the Shahejie Formation in the Qikou sag, Bohaibay Basin, China. We used core observations and descriptions of well F39 × 1 and performed X-ray diffraction, scanning electron microscopy, nitrogen adsorption analysis, and nuclear magnetic resonance analysis to investigate the shale lithofacies characteristics and types in member 3 of the Shahejie Formation, and their effects on shale oil enrichment. The results showed the following. (1) The lithofacies are divided into four types according to the shale’s laminar structure, lithological characteristics, mineral composition, and organic matter content: thin laminar shale, thick laminar shale, massive mudstone, and argillaceous siltstone. These are divided into six subcategories. Each lithofacies has thin vertical layers. (2) The thin and thick laminar shale layers have favorable conditions for shale oil enrichment, such as a high total organic carbon content (TOC) (1.1–1.6%), many micropores (with the diameter of 0.5–2 µm) and fissures, a high residual hydrocarbon content (1.0–2.3 mg/g), and a good source-reservoir relationship, making them suitable for shale oil exploration. (3) The degree of lamina development influences the organic matter and residual hydrocarbon contents, the number of micropores, and the degree of shale oil enrichment. The semi-deep and deep lake facies are favorable areas for shale oil development.

Sedimentological observations and geochemical characteristics of paleo-tsunami deposits along the east coast of Sri Lanka in the Indian Ocean

The 2004 Indian Ocean tsunami caused 230,000 fatalities and massive physical damage along the shorelines of the Indian Ocean. Holocene sedimentary archives along the coastline of Sri Lanka can provide evidence for similar past events. The objective of our current study is to investigate the sedimentological and geochemical characteristics of Sri Lankan paleo-tsunami deposits, and their chronology. Sediment samples were collected down to 10 m depth using core drilling at a sheltered site (low-lying swale depression) in Koddiyar Bay (Trincomalee) on the east coast of Sri Lanka. Visual stratigraphic observations and grain size analyses were carried out to identify lithological changes. Bulk sediments, shells, and wood fragments were used for 14C age dating. Seven sand layers were identified throughout the core in this marshy wetland. Sedimentological observations and geomorphological features show that sheltered/protected swales of the inner bay have a high potential for preservation of paleo-tsunami sediments. Three possible paleo-tsunami deposits were identified earlier than 700 years, ca. 2000 years, and ca. 2700 years. These paleo-tsunami sand layers exhibited relatively high total organic carbon (TOC) contents due to admixture of continental shelf and lagoon sediments. Analysis of paleo-tsunami records suggests that the Andaman Sea is vulnerable to both ‘low-risk and high-frequency’ and ‘high-risk and low-frequency’ type tsunamis, whereas other areas in the Indian Ocean are more prone to destructive and low-frequency type tsunamis. This study contributes to improving tsunami risk assessment and mitigation strategies along the east coast of Sri Lanka.

Impact of Terrigenous Organic Matter Input on Organic Matter Enrichment of Paleocene Source Rocks, Lishui Sag, East China Sea

To clarify the organic matter (OM) enrichment of the Lishui Sag, the factors influencing the variable abundance of OM in the Lingfeng Formation are studied using organic geochemical data. The source rocks of the Lingfeng Formation have medium–high total organic carbon (TOC) values (0.53–3.56%). The main type of kerogen is II2-III. Compared to the shallow marine subfacies source rocks, the TOC of the delta front subfacies source rocks is higher. The distribution of biomarkers shows that the redox environment of the delta front subfacies source rock is the sub-oxidizing and oxic environment, and the source rock is mainly supplied by terrigenous higher plants; the redox environment of shallow marine subfacies source rocks is a sub-reducing and suboxic environment, and the OM mainly comes from algae. The link between OM input and OM abundance demonstrates that terrigenous OM (TOM) input has a considerable influence on OM abundance. However, there is no obvious relationship between preservation and OM abundance, which suggests that preservation is not the determining element in OM enrichment. The strong sediment flux decreases the amount of time that OM is exposed to oxygen. As a result, delta front subfacies with large TOM input have a huge number of excellent source rocks. This paper proposes a “delta front-OM input model” for excellent source rocks.

Effect of land rehabilitation measures on soil organic carbon fractions in semi-arid environment

Soil erosion threatens the sustainable intensification of food systems among smallholder farmers in arid and semi-arid lands (ASALs). Intensifying adoption of soil mitigation and rehabilitation measures is thus needed urgently in these ASALs, but scaling up these measures depends on scientific evidence of their contributions to key components of sustainable intensification such as soil organic carbon. However, there is no information on how existing mitigation and rehabilitation measures influence soil carbon fractions and carbon management indices in ASALs. This study evaluated the influence of soil erosion mitigation and rehabilitation measures on soil carbon fractions and management indices in Arenic Lixisols of semi-arid environments in West Pokot County, Kenya. We evaluated different vegetation types (maize-beans intercrop and pastures) with and without two locally developed terrace designs for soil conservation (Fanya Juu and Fanya Chini). Combining terracing with annual cropping significantly increased total organic carbon (TOC). The highest TOC (13 g C kg−1) was recorded in pasturelands with terraces while degraded land with no intervention was found to have the lowest TOC (6.0 g C kg−1). Terraced farms with longer residence time (&amp;gt;4 years old) had significantly higher organic carbon than (&amp;lt;4 years old). Other soil properties remained stable with terrace age (1–5 years). Labile SOC and non-labile SOC differed significantly within and across vegetation types with or without terraces (p &amp;lt; 0.05). Pasture and crop systems with terraces had high labile SOC content of 5.9 g C kg−1 and 7.2 g C kg−1, respectively. Labile SOC followed the TOC trend with terrace age, i.e., increasing from 1 year to 5 years old. Combined pasture and terraces had a significantly higher carbon management index (CMI) of 161.7, or 14 times the CMI found in degraded systems with no interventions and 1.5 times the combined crop system with terraces. CMI was also directly correlated with residence time terraces had stayed in the crop system, increasing from 1 year to 5 years old. Contrary to CMI and other indices, the weighted enrichment ratio was found to inversely correlate with age of terrace. Improvement of carbon content and CMI resulted from restorative measures and likely improved soil quality and ecosystem functions. Although terraces play a significant role in the restoration of degraded soils as indicated by the above-mentioned changes, they are most beneficial when used in combination with croplands because of the high level of disturbance and flows of both inputs and outputs of carbon for these croplands.

Environmental controls on the microfacies distribution and spectral gamma ray response of the uppermost Jurassic–Lowermost cretaceous succession (Pimienta–Lower Tamaulipas Formations) in central-eastern Mexico

Organic-rich sediments of the Pimienta Formation were deposited in the Tampico-Misantla Basin during the Late Jurassic–Earliest Cretaceous. A sedimentological, spectrometric, microfacies and geochemical analysis was performed on a stratigraphic section recording the Pimienta–Lower Tamaulipas formational transition, to gain an understanding of the depositional conditions, and to decipher the main factors that control the gamma ray signal. This latter was achieved by comparison with other records. The studied succession spans from the upper part of the lower Berriasian Calpionella Zone to the lower part of the lower Valanginian Calpionellites Zone. Moreover, the microfacies data indicate it was accumulated in an outer ramp to basinal setting influenced by high energy events and the input of grains transported from shallower areas. Oxygen levels increased during the lastest Berriasian–early Valanginian. The organic matter preserved in these sediments has a mixed marine-terrestrial origin and is immature to early mature. Several records across the basin show that from the lower part of the Pimienta Formation to the lower part of the Tamaulipas Formation sediments change from radiolarian-rich microfacies with the highest Total Organic Carbon (TOC) content and Standard Gamma Ray (SGR) values to calpionellid-rich microfacies with the lowest TOC and SGR values. This shift is interpreted as controlled by the evolution of environmental conditions from eutrophic/oxygen-depleted to oligotrophic-partially oxygenated, which caused a progressive decrease in the organic matter burial and enrichment of authigenic U.

Evaluation of Lacustrine Shale Brittleness and Its Controlling Factors: A Case Study from the Jurassic Lianggaoshan Formation, Sichuan Basin

To investigate the brittleness of shale and its influencing factors, triaxial rock mechanics experiments, combined with X-ray diffraction, total organic carbon (TOC) measurement, rock pyrolysis, and scanning electron microscopy, were conducted on shales from the Jurassic Lianggaoshan Formation in the Sichuan Basin. BI1, based on the elastic modulus and hardness, BI2, based on mineral composition, BI3, based on strength parameters, and BI4, based on the post-peak energy of shale, were calculated. Additionally, the effects of mineral composition, density, hardness, and organic matter on the brittleness of shales were analyzed. The results show that the shale mineral compositions were dominated by quartz (mean of 45.21%) and clay minerals (mean of 45.04%), with low carbonate mineral contents and high TOC contents. The stress–strain curve showed strong brittleness characteristics. When comparing different evaluation methods, the brittleness evaluation method based on the stress–strain curve (damage energy) was found to be more effective than the mineral fraction and strength parameter methods. The higher the density and hardness, the more brittle the shale. The higher the organic matter and quartz content, the less brittle the shale. The brittleness of sub-member I of the Lianggaosan Formation in Well XQ1 was higher than that of sub-members II and III. This study investigated the brittleness of lacustrine shale and its influencing factors, which is beneficial for the development of shale oil in the Sichuan Basin.

Shale gas potential of Ordovician marine Pingliang shale and Carboniferous–Permian transitional Taiyuan-Shanxi shales in the Ordos Basin, China

The assessment of shale gas potential for the Ordovician Pingliang Formation and Carboniferous–Permian Taiyuan and Shanxi formations in the northwest margin of Ordos Basin, China provides insight into how fluctuation in depositional environments has a significant role on lithofacies and shale gas potential. To investigate the shale gas potential, a series of measurements (i.e. Rock-Eval pyrolysis, maceral composition analyses and X-ray powder diffraction, etc.) on representative outcrop samples were conducted to characterise shale properties. The organic matter from marine Pingliang shale is predominantly type I with a strong predominance of sapropelinite, whereas the transitional Taiyuan-Shanxi shales are dominated by types II to III kerogen. Furthermore, the Pingliang shale is characterised as a ‘poor’ source rock mainly owing to the lower total organic carbon (TOC) content (average 0.79 wt%) and higher maturity [average 1.78% in vitrinite reflectance (R o)], while the transitional Taiyuan-Shanxi shales are mostly characterised as ‘fair’ source rocks, and some samples with high TOC content (more than 2.0 wt%) present good source rocks. It is also found that the sedimentary environment, as a key factor determining the organic matter and TOC content, inevitably influences the type and content of minerals in shale, and controls the shale gas potential. For example, the transitional argillaceous Taiyuan-Shanxi shales are significantly different from the siliceous Pingliang shales, specifically, total clay content for the former is more than 50 wt%, while the latter is rich in quartz content (more than 70 wt%). Additionally, the quartz and clay contents of the Taiyuan shale range widely, especially the smectite content of I–S ML. The barrier coastal facies in the Taiyuan Formation are more conducive to the enrichment and preservation of organic matter because the Shanxi shale was deposited in shallow delta facies with a greater terrestrial influence. Conclusively, the Taiyuan and Shanxi formations have relatively good exploitation potential for shale gas, especially the relatively high TOC content (average 2.45 wt%) and moderate R o value (average 1.25%). For future exploration, selecting areas with relatively large shale thickness, high brittle mineral content, stable tectonics and better preservation conditions are key to optimising favourable exploration areas for shale gas. KEY POINTS The shale gas potentials of the argillaceous Taiyuan-Shanxi shales and siliceous Pingliang shale are compared. The influence of sedimentary facies on reservoir parameters of marine and transitional shales is established. This is a first detailed comparison of the marine and transitional shale gas potential in the northwest margin of Ordos Basin, China.

Pyrolytic and provenance evaluation of organic matter from the tertiary niger delta basin, nigeria: implication on hydrocarbon generation.

The present work deals with evaluation of organic matter based on detailed Rock-Eval pyrolysis techniques studies to evaluate hydrocarbon generation potential of source rocks by collecting twenty- nine shale samples from well cuttings in the Tertiary Formations of the Niger Delta, Nigeria. The values of vitrinite reflectance (0.57–0.74%Ro) and maximum (Tmax: 420–445°C) confirmed that samples are at early maturity to matured stage enough to generate liquid and gaseous hydrocarbon. The cross-plot between hydrogen index (HI) and oxygen index (OI) atomic ratio indicates that samples were predominant in the bituminous rank and having kerogen Type III makes it suitable for hydrocarbon generation. Rock-Eval pyrolysis analysis (Types II-III and Type III kerogen) on shale samples from the Niger Delta reveals organic matter of predominantly terrestrial origin based on type III kerogen. The organic matter (OM) assemblages suggests a marine setting but dominated by terrestrial inputs likely related to fluvial processes which is function of most delta system. Based on high total organic carbon (TOC) value of 5.42wt% and Type III kerogen made the shale an excellent source rock, with gas-prone kerogen. The high OI, low total sulphur (TS) suggests terrestrially derived OM and deposition in an oxic and dysoxic shallow marine environment. In addition, HI and Tmax values describe the samples as a characteristic Type III dominant kerogen and potential to generate oil and gases while the Tmax, consistently indicate an immature to mature on the shale organic matter.

Spherical activated carbons derived from resin-microspheres for the adsorption of acetic acid

Separation of small-molecule carboxylic acids, especially acetic acid, from wastewater is challenging due to its high-water solubility, acidity, and low concentration. In this work, resin-derived spherical activated carbon (RSAC) was directly prepared from resin spheres through facile pre-oxidation and carbonization processes. RSAC was characterized by SEM, N2 physisorption, XRD, Raman, element analysis and XPS. RSAC showed high removal rates (> 95.8 %) for a variety of small-molecule carboxylic acids. The initial adsorption capacity of acetic acid over RSAC was 23.4 mg/g and 94 % of the removal rate was retained after five successive adsorption-desorption cycles for 1000 mg/L acetic acid. In addition, RSAC showed a high total organic carbon removal rate (> 80 %) for the high-salinity effluent of catalytic wet air oxidation (CWAO) process. The adsorption of acetic acid over RSAC complied with the pseudo-second-order model and Langmuir model ideally, through Vander Waals force and pore-filling effect. Furtherly, discarded resin microspheres were used to prepare spherical active carbon, which showed 88.2 % removal of acetic acid (1000 mg/L). The benign scheme of “treating wastes by wastes” from economical and environmental aspects was realized.

Domestic Sewage Outfall Severely Altered Environmental Conditions, Foraminiferal Communities, and Ecological Quality Statuses in Front of the Nearshore Beach of Cigarras (SE Brazil)

This study aims to analyses the response of meiofaunal organisms (foraminifera) to disturbances caused by the diffusers of domestic sewage outfall at Cigarras beach, SE Brazil. Hydrographical, sedimentological (grain size and geochemical), and living benthic foraminiferal recorded in 2006 and 2007 analyzed in ten stations were compared with the same results analyzed in two control/reference stations (sampled in 2008). The results of this work show that, in the benthic environment of the Cigarras region, moderated hydrodynamic conditions, relatively high total organic carbon, total nitrogen, total sulfur contents, oxic water column and anoxic sediments, organic matter supplied by marine productivity and from mixed sources prevail. Living foraminiferal assemblages denote that the Cigarras region is undergoing environmental degradation due to progressive organic enrichment directly influenced by the domestic sewage outfall. The effluents discharged by the domestic sewage constrained the composition of foraminiferal communities (which include mainly stress tolerant species) with probable impacts on the entire marine trophic chain. Noticeably, the tolerant species Ammonia tepida, Bolivina striatula and Buliminella elegantissima dominated at the stations under the influence of the sewage outfall. In addition, Ammonia parkinsoniana was found in moderate abundances, and the moderate level of TOC enrichment by the sewage outfall did not prevent the survival of this sensitive species. The ecological quality status inferred from the diversity index Exp(H’bc) calculated on foraminifera showed the poor ecological status of benthic habitats in the area. Overall, this work highlighted the adverse effects of the sewage outfall on the benthic ecosystem in front of the Cigarras beach in Brazil. Future works should investigate the current ecological quality of the area to figure out if any change occurred since the present study sampling.

Characteristics and controlling factors of the Upper Permian Dalong Formation in northwestern Sichuan Basin, China

It has been generally accepted that the Permian shale is an important target for shale oil and gas exploration. In order to precisely predict the distribution of potential excellent source rocks of shale oil and gas, it is necessary to reveal the forming process and mechanism of high-quality source rocks, such as the Dalong Formation in the Scihuan Basin. In this study, 17 samples were collected from the Dalong Formation in Longfeng Quarry, Northwest Guangyuan City, Sichuan Province. The lithofacies, organic geochemistry, and pyrolysis of these samples were analyzed to evaluate the main factors controllingthe source rock formation. In particular, the influences of hydrothermal and paleoenvironmental conditions on the accumulation of organic matter were analyzed. The total organic carbon (TOC) content of the samples, which ranges from 0.05% to 12.21%, is closely related to the lithology. High TOC has been generally observed in rock intervals developed in a deep-water sedimentary environment, including siliceous rock, dark shale, and siliceous shale. The peak pyrolysis temperature of the samples ranges from 444°C to 462°C, indicating a mature stage. Thin-section observation, combined with the results of previous studies, has confirmed that the source of the organic matter is mainly marine phytoplankton, such as algae and radiolarians, ostracods, and other marine organisms, which consist of these high-quality source rocks. The ratio of trace elements, such as Ni/Co, V/Cr, U/Th, and V/(V + Ni) indicate that high-quality source rocks are mainly formed in anoxic restricted environments. The hydrothermal activity of submarine volcanoes provided many nutrients and compounds, resulting biological prosperity and improving primary productivity. This is simultaneously conducive to the formation of anoxic environments and the preservation of organic matter.

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.

Characterization and drivers of haloacetic acids in New York State

AbstractThe formation of disinfection byproducts (DBPs) in finished drinking water is an ongoing challenge for public health agencies and water utilities. The Fourth Unregulated Contaminant Monitoring Rule data were used to assess the prevalence and drivers of haloacetic acids (HAAs)—a class of DBPs—in New York State's (NYS) public water systems, with a focus on total measured (HAA9), regulated (HAA5), brominated (HAA6Br), and unregulated (HAA4) HAAs. The concentrations of all HAA groups in NYS are found to be similar to those nationally, with HAA4 composing approximately 20% of HAA9. Concentrations of all HAA groups are lowest in groundwater and highest in surface waters across NYS systems. Higher total organic carbon (TOC) concentrations lead to elevated HAA9 and HAA5, while higher bromide concentrations favor more HAA4 and HAA6Br. HAA4 concentrations are well predicted with pre‐oxidation/disinfection types, HAA5, TOC, and bromide concentrations, with an adjusted R2 of 70%.