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The generation of surface free energy parameters calculated from contact angle data is a burdensome and time-consuming process. To facilitate these calculations, computational algorithms using three different programming languages—MATLAB, C and Python—were developed and validated by surface properties determination of PO and CPO. The results indicated that the surface free energy parameters calculated using the three algorithms were consistent. The unknowns were obtained directly from within the C and Python programs, however, indirectly from within MATLAB function. In addition, the assembly statements of the C function were longer than those of the other two. The obtained results were also compared with those from an IGC analysis. It showed that the γ S D values determined using the contact angle methods were consistent, although lower than those obtained by IGC analysis. Compared to γ S D , the γ S S P component contributed less to γ S T . The lower γ S D and γ S S P values for CPO which added up to a lower γ S T value, could reduce filler particle/particle interactions, allowing a better dispersion in a polymer matrix. [ABSTRACT FROM AUTHOR]

Mollusk shells, such as clam, mussel, oyster and pearl oyster shells, are potential candidates for commercial calcium carbonate-based fillers. In this work, the surface properties of colored pearl-oyster-shell-derived filler (CMF) were investigated with comparison to those of pearl oyster shell powder (MSP), using an inverse gas chromatography (IGC) method and contact angle measurements. A developed computational model for the interpretation of surface free energy heterogeneity distributions was applied to both samples. The contact angle measurements revealed an amphiphilic nature. The dispersion component of surface free energy for both samples calculated using the Owens–Wendt–Kaelble (OWK), van Oss–Chaudhury–Good (vOCG) and Wu methods were consistent with those determined using the IGC method. The deconvolution of surface energetic sites confirmed their energetic heterogeneity. The CMF displayed lower work of cohesion, which could be beneficial to the fabrication of polymer composites, as typically reduced filler particle-particle interactions would result. [ABSTRACT FROM AUTHOR]

The solid surface characterization using contact angle measurement is complicated and time-consuming. In this work, two computational algorithms in MATLAB and C were developed and validated by the surface properties determination of talc filler (TCF) and colored talc filler (CTCF). The results indicated that, the surface free energy parameters calculated using the two algorithms for both samples were consistent. As compared to the MATLAB function, the assembly statements of C function were longer, although the unknowns can be directly obtained using this toolbox. The γ S D values determined by the Owens-Wendt-Kaelble (OWK), van Oss-Chaudhury-Good (vOCG) and Wu methods were consistent and contributed a major part of the γ S T . Compared to γ S D , the γ S SP component contributed less to γ S T , implying a lower polarity for both samples. The lower γ S D and γ S SP for CTCF added up to a lower γ S T value, which could reduce filler particle-particle interactions. The mechanical properties study of acrylonitrile-butadiene-styrene (ABS) matrix filled with the two fillers showed that the incorporation of them played mainly a reinforcing role, and a better performance for CTCF was observed. [ABSTRACT FROM AUTHOR]

The disposal of waste cathode ray-tubes (CRTs) from old televisions and discarded computer monitors has become a major environmental concern worldwide. In this work, an open-loop recycling method was developed to synthesize zeolites using CRT funnel glass as the raw material. The effects of hydrothermal temperatures and pressure, n(SiO 2 /Al 2 O 3 ) molar ratios and hydrothermal time on the resulting products were investigated. The results indicated that hydrothermal temperatures and pressure played critical roles in zeolite synthesis. Amorphous phases were detected at lower temperatures (80–100 °C) and pressure (0.47–1.01 bar) with n(SiO 2 /Al 2 O 3 ) = 2.0. At the temperature of 110 °C (pressure 1.43 bar), NaA formed with a mixture of NaP1 and Faujasite. With further increase in the temperature and pressure, the unstable NaA and Faujasite disappeared, and Hydroxysodalite developed. The influence of n(SiO 2 /Al 2 O 3 ) ratios on resulting products revealed a single phase of NaA was formed at the ratio of 1.5 and a mixture of NaA and Faujasite at the ratio of 2.0. Prolonging hydrothermal time, however, could promote zeolite crystallization, and NaA gradually developed with an increase in the time from 2 to 6 h at n(SiO 2 /Al 2 O 3 ) = 1.5. By comparison, crystallization phases were observed only when the time was longer than 8 h at n(SiO 2 /Al 2 O 3 ) = 2.0. [ABSTRACT FROM AUTHOR]

Extensive studies on methane seeps have facilitated the exploration of potential gas hydrates and have revealed biogeochemical processes on the seafloor. In this study, a short core, GG00, was collected from the Shenhu area, South China Sea. By combining various geochemical and mineralogical methods—including planktonic foraminiferal AMS14C dating, as well as their carbon and oxygen isotopes, chromium-reducible sulfur (CRS) content and δ34S values, and hand-picked pyrite and other minerals, we identified a methane seeps that has been stable since the end of the Last Glacial Period. Extremely negative values of δ34S for CRS (as low as −49.7‰) indicated that only organoclastic sulfate reduction and its coupled sulfur intermediate disproportionation were present in the shallow sediments (from 0 to 209 cmbsf). Conversely, the increasing TS and Mo content and the progressively more positive δ34S values (up to −34.76‰) of the CRS indicated enhanced sulfate reduction coupled with the anaerobic oxidation of methane (SR-AOM) in deeper sediments (between 209 and 370 cmbsf). In addition, a large number of hypautomorphic-euhedral elemental sulfur (ES) microcrystals was found at 237 cmbsf using scanning electron microscopy, and energy-dispersive X-ray spectroscopy identified the upper edge of the sulfate–methane transition zone (SMTZ), which was close to the position that was determined from other data (e.g., major and trace elements as well as CRS and its δ34S value). The construction of a stratigraphic framework based on planktonic foraminiferal AMS14C dating and carbon and oxygen isotopes, combined with the large number of framboid pyrites consisting of cubic microcrystals found further below the SMTZ, suggests that this SMTZ has been relatively stable since the end of the Last Glacial Period. In addition, discrepancies in the aggregation morphology of cubic pyrite at different intervals are indicative of variations in Fe and S supply and growth space. Therefore, this study demonstrates the significance of detailed geochemical and mineralogical signatures in revealing the correlation between methane seep and climate. • Subhedral-euhedral elemental sulfur microcrystals are discovered in proximity of SMTZ. • Carbonate pellet and aggregates indicate the presence of SR-AOM. • Framboids formed by cubic pyrites indicate the SMTZ has been stable for a long duration. • All the Geochemical and mineralogical characteristics reveal a stable methane seep. [ABSTRACT FROM AUTHOR]

Globally, research aiming to reveal the unique biogeochemical processes and gas hydrate potential in methane seep areas is well established. Furthermore, methane seeps discovered in the South China Sea (SCS) have been widely studied and have achieved significant results. Herein, by systematically analyzing sedimentary samples from the Shenhu area, SCS, we discovered a methane seep that was once active during the last glacial period, particularly the Last Glacial Maximum (LGM) period, and fixed at the seafloor for ∼10 ka. This discovery was achieved by integrating the features of the glauconite within the foraminifera chamber, different morphologies of pyrites, and unique framboid goethites (pyrite pseudomorphs). In addition, this study accounted for the high chromium-reducible sulfur content and extremely negative δ34S values (from −50.78 to −46.92%) between 121 and 231 cmbsf, the Mo content and its correlation with total sulfur (TS) and total organic carbon (TOC), the TS/TOC ratios of sediments, the results of AMS 14C dating, and the results of planktonic foraminifera analysis in the case of carbon and oxygen isotopes. Glauconite, which is usually considered a product associated with transgressive deposits and condensed sections, is widely found in warm climatic intervals. However, these intervals are generally associated with methane emission events. Thus, our results demonstrate another mechanism for the formation of glauconite in methane seeps during the LGM. Furthermore, the existence of framboid goethites implies that this methane seep has been subsiding since the end of the LGM and that few pyrites that formed previously were reoxidized. Notably, this study is the first to report a systematic investigation of methane seep activity during the last glacial period by the indication of authigenic minerals, such as glauconite and framboid goethite, in the SCS. Overall, our results show a direct relationship between methane seep activity and climatic variation. • The diverse morphologies of pyrites indicate various formative environments. • The glauconite records the changed redox condition near the seafloor surface. • The occurrence of Fe (hydrogen) oxide indicates the methane seeps is inactive at present. • All the mineralogical and geochemical characteristics reveal a subsided methane seep. [ABSTRACT FROM AUTHOR]

A better understanding of filler's surface properties is critical for determining the most effective polymer reinforcement fillers. In this work, a colored talc filler (CTF) was prepared and its surface properties were comparatively studied to those of talc filler (TF), using inverse gas chromatography (IGC) and contact angle methods—Owens–Wendt–Kaelble (OWK), van Oss–Chaudhury–Good (vOCG) and Wu. The results indicated that the dispersive component ( γ S D ) for both samples contributed a major part (68–81%) of the total surface energy ( γ S T ), and displayed a decreasing trend with increasing surface coverage, meaning the fairly energetic surface heterogeneity for them. The γ S D values determined by the contact angle methods were consistent, although lower than those using IGC analysis. The specific component ( γ S SP ) calculated by the contact angle methods were also consistent and lower than those calculated using IGC. The specific Gibbs free energies of adsorption (ΔG sp ) changed with surface coverages, further confirming the heterogeneous nature of both samples. The significantly lower γ S T value for CTF could reduce filler particle-particle interactions, allowing a better dispersion in matrix, and thus lead to an improvement in mechanical performance of CTF/polymer composite. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is an important nutrient and has an important impact on global primary productivity. Presently, the dynamics of the P cycle in low sulfate, anoxic settings are largely unknown. In this study, the adsorption–desorption behavior of Fe-bound P, organic-P, loosely-bund P, detrital apatite P, and refractory P was described in the sulfate and methane transition zone (SMTZ) at site 973–4 in the cold-seep area of the Taixinan Basin, South China Sea. Results showed that the Fe-bound P and organic-P were influenced by sulfate-driven anaerobic oxidation of methane (SD-AOM) and metal-driven anaerobic oxidation of methane (MD-AOM), and subsequently, the Fe-bound P and organic-P were released as HPO 4 2− into the pore water. Meanwhile, significant increases were detected in authigenic carbonate fluorapatite (P CFA) and vivianite within the MD-AOM zone, which indicate that this zone is an important P-sink area. The MD-AOM plays an important role in the formation of P CFA and vivianite because MD-AOM provide the necessary HPO 4 2− and Fe2+ for the formation of these minerals. Our findings have major implications for understanding the P cycle in low sulfate, anoxic settings and are important for understanding the influence of MD-AOM on the phosphate cycle. • Data were indicative of the presence of metal-driven anaerobic oxidation of methane • Changes in various forms of P were observed at the MD-AOM zone • The metal-driven anaerobic oxidation could influence P concentrations in the sinks [ABSTRACT FROM AUTHOR]

In this work, the combustion and pyrolysis characteristics of a waste TV plastic shell sample were investigated using a powerful Thermogravimetric-Fourier Infrared Spectrum-Mass Spectrum (TG-FTIR-MS) technique. The decomposition mechanisms of plastic waste and fate of bromines in both thermal processes were probed as well. The TG analysis revealed that the combustion rate was larger than that of pyrolysis at temperature of 456 °C below, whereas it decreased at temperature of 456–605 °C. As a result, the total weight loss was equivalent at temperature of 605 °C for both processes. The FTIR analysis indicated the plastic combusted vigorously at 300–500 °C and 800–900 °C. As a comparison, it decomposed drastically at 300–400 °C and 500–900° in pyrolysis. The MS analysis showed that the release of brominated products HBr, CH 3 Br, C 2 H 5 Br, C 3 H 5 Br, C 3 H 7 Br and C 3 H 5 BrO increased with an increase of temperature and reached maximum at 400–600 °C in both thermal processes. The release intensities of larger molecules C 6 H 5 Br, C 6 H 5 BrO and C 6 H 4 Br 2 were in the descending order of C 6 H 5 Br > C 6 H 4 Br 2 > C 6 H 5 BrO. It was not significant in the evolved products and decomposition pathway for both thermal processes. The entire decomposition of TV plastic shell sample could be divided into three stages, taking account of the evolved products. The backbone in acrylonitrile butadiene styrene resin and tetrabromobisphenol A first broke at 350 °C below, resulting in the form of 2-bromophenol, styrene, acrylonitrile and polybutadiene. Subsequently, the resulted 2-bromophenol debrominated forming HBr, which further reacted with hydrocarbons resulting in various brominated derivates. In addition, many small molecules, including CO 2 , CO and CH 4 were generated in this stage. Further increasing temperature to 550 °C above, larger brominated derivates decomposed and smaller molecules predominated. Unlabelled Image • The combustion and pyrolysis characteristics of waste TV plastic shell was investigated. • The decomposition mechanism of plastic and fate of bromine were probed. • It offered practical support for the thermal treatment of flame retardant plastics. [ABSTRACT FROM AUTHOR]

Highlights • A negative δ13C drift of planktonic foraminifera and depositional disorder are recorded at Site 973-4 in the pre-Holocene sediments. • The benthic δ13C at Site 973-4 primarily reflects the carbon-reservoir variations on the glacial-interglacial scale. • The foraminiferal assemblage characteristics in the Dongsha pre-Holocene sediments are comparable to the counterpart in other cold seeps. Abstract A 1375-cm-long gravity core (Site 973-4) was acquired from the Dongsha cold seep area of the northeastern South China Sea (SCS). We measured its stable isotopes of planktonic foraminifera and investigated benthic foraminiferal assemblage compositions. Accelerator mass spectrometry 14C analysis of planktonic foraminifera shows that some intervals are dated to Marine Isotope Stage (MIS) 3. Pulleniatina obliquiloculata has positive δ13C (0.25–1.25‰) except for a negative carbon isotopic excursion (up to δ13C = −1.15‰), but its light-carbon sources remain elusive. The benthic δ13C values (Uvigerina) of non-seep and cold-seep boreholes from the SCS have no systematic difference. Therefore, the benthic δ13C at Site 973-4 did not record the enhanced seepage activities (if occurred) during the last sea-level lowstand in the Dongsha area. In the pre-Holocene sediments, the foraminiferal assemblages have lower diversities, Shannon-Wiener indices, evenness indices, Simpson indices and higher calcareous proportions like typical cold-seep settings. The changes in oxygen levels (lower in the glacial period than those in the Holocene) indicated by foraminiferal indices reflect either bottom-water oxygen variations on the glacial-interglacial scale or enhanced seepage activities during the last glacial period. [ABSTRACT FROM AUTHOR]

Summary: The amount of sewage sludge has increased remarkably with the acceleration of urbanization and the promotion of municipal wastewater treatment. Hydrogen is a promising clean fuel, considering the emerging global energy crisis and the growing demand for environmental protection. Producing hydrogen from sewage sludge through anaerobic fermentation is an economical and environmentally sustainable technology. Therefore, in this work, the mechanism of hydrogen production from sludge is critically reviewed and clarified. Current researches including sludge pretreatment and key factors affecting hydrogen production were investigated as well. Some challenges still remain, such as almost all studies feature experiments in batch cultures, and the hydrogen yields were not large. Further studies are needed in this arena, such as inhibiting hydrogen‐consuming bacteria, culturing, and screening high‐efficiency bacteria. The mechanism of hydrogen production from anaerobic co‐digestion, their factors, and techno‐economic evaluation need be further studied as well. [ABSTRACT FROM AUTHOR]

Recent breakthroughs in Pearl River Mouth basin (PRMB) regarding offshore hydrocarbon exploration have shifted the focus from deepwater area to ultra-deepwater area (>1500 m water depth), and the southern sub-sag of Baiyun sag, Liwan sag, and the Shunhe Uplift between them constitute the front area for PRMB ultra-deepwater hydrocarbon exploration. This study investigated the source-rock strata (i.e., Eocene Wenchang Formation and Enping Formation) and reservoir fluids (mainly CO 2 with small amounts of oil and alkane gas) in the first exploratory well (namely W21, drilled at Shunhe Uplift), aiming to unscramble the source kitchen and hydrocarbon prospect information in this ultra-deepwater area. Biomarker and transgressive history analysis of source-rock strata jointly determined the Wenchang Formation and Enping Formation to be marine sediments in the Liwan sag, while marine and lacustrine sediments in the Baiyun southern sub-sag, respectively. The oil biomarkers and isotopes of alkane gas evidenced prospect for mature oil and oil-associated gas in this ultra-deepwater area, and the correlated source analysis determined the source rocks in the two sags have an advantage of aquatic organic input, indicating a good hydrocarbon-generating potential. Additionally, the regional distribution of terrestrial source-specific biomarkers (i.e., oleanane and bicadinanes) in PRMB deep to ultra-deep water areas traced the terrestrial source area and revealed a significant less input of terrigenous organic matter at the two ultra-deepwater sags. The isotopic analysis of reservoir non-hydrocarbon gases determined the CO 2 to be mantle-derived magmatic origin. The present reservoirs are a result of displacement of early charged oils by posterior migrated CO 2. In conclusion, this PRMB ultra-deepwater area has a considerable prospect for mature oil; however, the frequent volcanism since the Pliocene poses great risks to hydrocarbon exploration. • Identified the origin and type of oil and gas in CO 2 -charged reservoirs in well W21. • Deduced the sedimentary environment and organic input of source rocks in PRMB ultra-deepwater sags. • Revealed a risk of displacement of hydrocarbon reservoirs by magmatic CO 2 in PRMB ultra-deepwater area. [ABSTRACT FROM AUTHOR]

Separating cathode material and Al foil from spent lithium-ion batteries (LIBs) is a critical step for LIBs recycling. As compared to chemical dissolving and decomposition, the pyrolysis pretreatment is an alternative and simple method. In this work, the pyrolysis kinetics of cathode material were comparatively studied using various isoconversional methods, including Flynn-Wall-Ozawa (FWO), Friedman, Kissinger-Akahira-Sunose, Starink, Tang, and Boswell. The thermal degradation mechanism was investigated by the Coats-Redfern (CR) and master-plot methods as well. The thermogravimetric analysis revealed that cathode material decomposition could be divided into three stages with mass losses of 1.51%, 0.787%, and 0.449%, respectively. Activation energy (Eα) calculated using the six model-free methods showed a similar trend, gradually increasing as the degree of conversion (α) increased from 0.001 to 0.009, and then significantly elevating. The FWO method gave the best fitting and Eα values first increased from 12.032 to 24.433 kJ·mol−1 with α elevating from 0.001 to 0.009, then increased further to 43.187 kJ·mol−1. Both CR and Criado methods indicated that the degradation of cathode material can be explained by the diffusion models. Implications: The rapid growth in the production and consumption of lithium-ion batteries (LIBs) for portable electronic devices and electric vehicles has resulted in an increasing number of spent LIBs. Thermal treatment offers advantages of high-efficiency and simple operation. Understanding the thermal process of spent LIBs and probing its kinetic are significant for the large-scale treatment. Through this study, it will be significant for the reactor designing and optimizing in practice. [ABSTRACT FROM AUTHOR]

Polyurethane foam (PUR) from waste refrigerators has long been recognized as a difficult-to-treat electronic waste, due to its bulkiness, low weight and chlorofluorocarbon content. In this work, the combustion and pyrolysis behaviors of PUR were investigated using a versatile thermogravimetric–Fourier infrared spectrum–mass spectrum (TG/FT-IR/MS) technique. The decomposition mechanisms in both thermal processes were determined, and the fate of halogens was probed well. TG analysis indicated that the PUR combustion could be divided into three main stages with peak temperatures of 328, 557 and 970 °C, respectively. As a comparison, its pyrolysis could be divided into two steps with peak temperatures of 332 and 970 °C. FT-IR results indicated that the PUR combusted vigorously at 400–600 °C, whereas it decomposed drastically at the lower temperature of 200–400 °C in pyrolysis. MS analysis revealed that the urethane bonds in the PUR molecules broke into isocyanates and polyols at 200–400 °C in combustion, which further decomposed at 400–650 °C and reacted with halogens. However, the ester bonds ruptured into aromatic nitro compounds and ethers at 200 °C below in pyrolysis. At higher temperature range of 200–500 °C, more halogenated derivatives were detected with lower intensity. In addition to the halogenated products such as chlorofluorocarbons, chlorobenzene, dichlorobenzene, o-chloroaniline, and trifluoroacetone, small molecules of hydrogen cyanide, ammonia, carbon dioxide, carbon monoxide were all detected. [ABSTRACT FROM AUTHOR]

The back cover image is based on the Review Paper A state‐of‐the‐art review of biohydrogen producing from sewage sludge, by Zhitong Yao et al., https://doi.org/10.1002/er.4188. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Sedimentary hydrocarbons were measured to trace the OM origin down core Site 4B. • Hydrocarbon distribution indicates a terrestrial higher plant source in most of sediment intervals. • Hydrocarbon seepage is likely responsible for the occurrence of mature OM at some intervals. Abstract The hydrocarbons in sedimentary organic matter (OM) at Site 4B in the Pearl River Mouth Basin (PRMB), northern South China Sea (SCS) were analyzed. The odd/even predominance (OEP) of long chain n -alkanes (> n -C 24) with CPI (carbon preference index) values from 1.62 to 3.80 and n -C 29 / n -C 31 being the two most abundant in most of the samples are strongly indicative of a terrestrial higher plant source, and the even/odd predominance (EOP) distribution of mid-chain n -alkanes (n -C 16–22) suggests a marine bacterial input, probably chemical autotrophic bacteria. However, the biomarker distributions at the 65–70 cm, 80–85 cm and 85–90 cm intervals show a similar to those of crude oils, which were characterized by a dominance of an unresolved complex mixture (UCM) in the n -C 20+ region, low CPI values (<1.5) of long chain n -alkanes, low values of ββ/(αβ + ββ + βα)-C 30 hopane (<0.15), and high values (>9) of total tricyclic terpanes/αβ-C 30 hopane. These features are typical characteristics of mature OM that has experienced catagenesis and metagenesis, suggesting that outside hydrocarbons migrated into these three intervals. In terms of petroleum systems developed in the PRMB, hydrocarbon seepage from deep source rocks via a diaper structure and fault system is proposed to be responsible for the occurrence of this mature OM. [ABSTRACT FROM AUTHOR]

The Shin-Yan-Ny-Hu (SYNH) MVs are typical subaerial mud volcanoes in southwestern Taiwan. The lipid biomarkers and their stable carbon isotopes were firstly examined to delineate the mud breccia sources, depositional environments, thermal maturity, probable source strata and the migration framework of volcanic fluid. The sediment organic matter within active SYNH MVs principally stemmed from the petroleum derivatives, bacteria and terrigenous C 3 plants suggested by the following indicators: the CPI of n -alkanes (∼1); the distribution and δ13C values of saturate, fatty acids and the plot of Pr/ n -C 17 vs. Ph/ n -C 18 ratios. The Pr/Ph ratios, the plot of Pr/ n -C 17 vs. Ph/ n -C 18 and the plot of Pr/Ph vs. O/C 30 Hopane ratios implied that the sediment organic matter was deposited in a marine deltaic sedimentary environment under an oxic depositional environment. The C 30 βα/C 30 αβ, T max , 22 S/(22 S + 22 R) ratios of homohopane (C 31) and bishomohopane (C 32), MPI 1 , MPI 2 , F 1 , F 2 , T max vs. HI and the Pr/ n -C 17 vs. Ph/ n -C 18 ratios revealed that the Type III organic material was early thermal maturity and the burial depth of mud breccia matrix was estimated around 4–5 km bsf. • The organic matter of SYNH MVs was derived from petroleum derivatives, bacteria and terrestrial higher plants. • The mud breccia matrix was deposited in a marine deltaic environment under an oxidized sedimentary environment. • The source organic matter was early thermal maturity, and the burial depth of mud breccia matrix was about 4–5 km bsf [ABSTRACT FROM AUTHOR]

This study investigated the composition of long-chain alkyl diols, triols, sec-alcohols, hydroxyl acids, and other hydroxylated compounds in Azolla imbricata and compared the organic alcohol components of Azolla filiculoides, Azolla microphylla, and South China Sea (SCS) sediments in order to investigate the possible indication of Azolla being the biological source of diols and triols in SCS sediment. Large amounts of diols, monohydroxy acids, and sec-alcohols with internal hydroxy groups at ω20 were detected in the three types of Azolla. Among these, 1,ω20-diol and ω20-hydroxy acid exhibited strong even-odd predominance distribution, whereas ω20- sec-alcohol exhibited strong odd-even predominance distribution. In addition, small amounts of diols, triols, and dihydroxy acids with internal hydroxy groups at 9, 10 or ω9, ω10 were detected, among which the chain length of C was predominate. Compounds having similar structures as those in Azolla reflected a similar biosynthetic pathway: ω20-hydroxy acid exhibiting even-odd predominance distribution is decarboxylated to ω20- sec-alcohol exhibiting odd-even predominance distribution and converted to 1, ω20-diol with even-odd predominance distribution by acyl reduction; ω9, ω10-hydroxy acid is converted to 1,20,21(1, ω9, ω10)-triol by acyl reduction, and then converted to 9,10-diol by hydrogenation and dehydration. The alcohol components in A. imbricata were clearly not the biological source of 1,13/1,14/1,15-C diols and 1,3,4-C triols in the SCS sediment. Certain marine diatoms might be the source of 1,14-C diol in inshore sediment, but the biological source of diols and triols in the SCS sediment requires further investigation. [ABSTRACT FROM AUTHOR]

A high gas production rate is critical for commercial exploitation of hydrate. Most marine hydrates deposit in the silty or clay sediments with low permeability, and gas production rate is low. Herein, a novel deployment of well, radial three-branch horizontal well was numerically investigated to enhance the gas production. A 3D geological model was established based on field trial in the Shenhu Area of the South China Sea. The simulation showed similar gas and water production for single and multi-branch horizontal wells with same length of 250 m. The depth in which well deployed dramatically affects the gas and water production, and which increases with the length of multi-branch well. Meanwhile the ratio of free gas originally distributed in three-phase and gas layers also increases with the length, which is 50% for 1200 m well. The interference around the intersection of branches enhances temperature recovery and the dissociation of underlying hydrates. The standard energy return on investment analysis shows that the economic potential increases linearly with the length of multi-branch well and obviously depends on the content of initial free gas. However, the production balances investment confines only to tens or hundreds of days for all model scenarios. • A novel radial three-branch horizontal well is adopted to investigate the enhancement of gas production from hydrate. • Depth of multi-branch well (various contact formation) highly affects gas production. • The deployment of the horizontal well within three-phase layer is feasible for high gas production. • Interference of branches enhances temperature recovery rather than gas recovery. • Cost-benefit balance is analyzed and further technical improvement is needed to meet the economic criterion. [ABSTRACT FROM AUTHOR]

After the detection of the 1,20,21-C long-chain triol in some sediments and freshwater pteridophytes, in this study, a new homologous long-chain triol, 1,3,4-C, is detected for the first time in the Site4B core sediment in the northern South China Sea. The hydroxyl location and length of the carbon chain of this newly discovered triol differ from those of 1,20,21-C triol. The test results of its molecular distribution and individual carbon isotope reveal that 1,3,4-Ctriol has a good correlation with n-C even carbon-numbered long-chain fatty alcohols, with R ( n=68) values of 0.905, 0.929 and 0.903, respectively, and its carbon isotope composition, at-32.3‰±1.9‰, is similar to that of n-C, at-29.13‰±0.87‰,-32.98‰±1.28‰, and-32.98‰±1.28‰. 1,3,4-C triol from the Site4B core sediment and terrigenous long-chain fatty alcohol ( n-C) show highly consistent distribution trends in the entire section; thus, the former could serve as a proxy indicator of the terrigenous input. Considering that the 1,20,21-C triol in previous research belongs to Azolla, which are fresh water pteridophytes, the 1,3,4-C triol identified in this study might have similar biogenetic derivation. Thus, determination of its biogenic area and growing environment could provide potential organic geochemical evidence supporting the terrigenous input and source in the northern South China Sea. [ABSTRACT FROM AUTHOR]

Three cores of marine sediments from the Shenhu area in the northern part of the South China Sea were analyzed by XANES analysis for sulfur speciation. The area has been investigated for the presence of hydrocarbons and potential gas hydrate formations. Cored samples of site 4B showed a specific profile of sulfur speciation with sharp and frequent variations in relative contents of sulfate and sulfide, which differed greatly from the profiles obtained for the sediments taken at sites 5B and 6A. The upper part of core 4B (of 0–95 cm) was soft and rich in pore water, containing mainly coarse silt sand. The lower part of the core (i.e., depth > 95 cm) was relatively dryer and darker in color, and dominated by silts and clay resembling sediments from mud volcanoes. The sulfur speciation results revealed that sulfate makes up almost 100 percent of all sulfur species in the upper part of the core 4B, which indicates strong oxidizing conditions, whereas the lower part of the same core has high relative contents of sulfide, sometimes close to 100% S 2− . In the lower part of the core, the relative content of sulfide and sulfate changes rapidly and frequently, indicating rapid changes of oxidizing and reducing conditions. On the other hand, the vertical profiles of sulfur species for the cores from sites 5B and 6A are relatively consistent with lower sulfide contents indicative of stable and weaker reducing conditions. We hypothesize that the frequent and sharp variations in the ratios of sulfide to sulfate at site 4B may indicate some intermittent eruption of methane with clay from petroleum reservoirs underneath the sea floor over a relatively short period of time. [ABSTRACT FROM AUTHOR]

In order to understand the response of authigenic pyrite to gas hydrate geo-systems, pyrite tubes or rods at the sulfate-methane transition (SMT) zone of core GC10 from the northern continental slope of the South China Sea (SCS) were investigated. In situ X-ray diffraction (XRD) results show that the pyrite tube consists of pyrite micro-crystals with trace amount of graphite in the inner tube. Scanning electron microscope (SEM) observations of pyrite tubes indicate various aggregations in the form of framboidal, euhedral, and colloidal pyrite microcrystals. Typical framboidal pyrite is considered as packing of octahedral microcrystals. Interestingly, many framboids in the tubes consist of round or irregular microcrystals and have an outer crust that consists of secondary pyrite. The size of the framboids in the inner wall of the tube is larger than that in the middle wall or foraminifer-filled pyrite. High-resolution transmission electron microscopic (HRTEM) images show marcasite lamellae defects in the spherulitic pyrite crystals, which reveal different solution conditions during the pyrite precipitation. Nano-foil-like graphitic carbon was observed to be closely associated with the pyrite spherules. The occurrence of both marcasite layers and nano-foil-like graphitic carbon suggest that the migration of methane from deep sediment. It is suggested that the formation of pyrite serves as a catalyst during the reaction from methane to elemental carbon under the anaerobic oxidation of methane. Meanwhile, this reaction results in local acidification of the solution inside the pyrite tubes, which favors marcasite lamellae growth on the host pyrite substrate. [ABSTRACT FROM AUTHOR]

Distinct pyrites have been recovered from a shallow sediment core from Site 4B in the Shenhu area of the northern South China Sea. Based on the lithology, texture and structure of sediments, the stable sulfur isotope of pyrite and the total organic carbon (TOC) concentration of the sediments, a distinctive sediment interface is identified at a depth of about 1 m below the seafloor in the core sediments. The pyrites only accumulate in the lower part of the core as rods and foraminifera-infillings, and mainly within three intervals marked by high pyrite concentrations. The amount of pyrite in the sediments shows no remarkable correlation with TOC in the Site 4B core sediments. The stable sulfur isotopes of the pyrite have extremely negative values ranging from −41.69‰ to −49.16‰. They are considered to be the mutual product of sulfate bacterial reduction and sulfur bacterial disproportionation. Our research proposes that Site 4B might be located in or near a possible mud volcano sedimentary environment; a large amount of methane could migrate from deep to shallow sediments in an active mud volcano and thereby play a key role in the intensity of sulfate bacterial reduction and the amount of pyrite formed at Site 4B. Further, the variation in flux of deep methane fluid by intermittent mud volcanic eruptions might result in the deposition of authigenic pyrite intervals. [ABSTRACT FROM AUTHOR]

Here we reported the fatty-acids and their δ13C values in seep carbonates collected from Green Canyon lease block 185 (GC 185; Sample GC-F) at upper continental slope (water depth: ∼540 m), and Alaminos Canyon lease block 645 (GC 645; Sample AC-E) at lower continental slope (water depth: ∼2200 m) of the Gulf of Mexico. More than thirty kinds of fatty acids were detected in both samples. These fatty acids are maximized at C16. There is a clear even-over-odd carbon number predominance in carbon number range. The fatty acids are mainly composed of n-fatty acids, iso-/anteiso-fatty acids and terminally branched odd-numbered fatty acids (iso/anteiso). The low δ13C values (-39.99‰ to -32.36‰) of n-C12:0, n-C13:0, i-C14:0 and n-C14:0 suggest that they may relate to the chemosynthetic communities at seep sites. The unsaturated fatty acids n-C18:2 and C18:1Δ9 have the same δ13C values, they may originate from the Beggiatoa/Thioploca. Unlike other fatty acids, the terminally branched fatty acids (iso/anteiso) show lower δ13C values (as low as -63.95‰) suggesting a possible relationship to sulfate reducing bacteria, which is common during anaerobic oxidation of methane at seep sites. [ABSTRACT FROM AUTHOR]

The lithological characteristics of subsurface formations control the variations in the permeability. Herein, the effect of lithological rhythm on gas production was numerically investigated for depressurization applied in a confined hydrate reservoir. The lithological rhythm structures from simple uniform, positive, and reverse rhythms to complex composite rhythms were designed. The water-to-gas ratio showed that economic feasibility of all rhythms varied with the expansion of the hydrate dissociation region. The depth of high permeability region affected the hydrate dissociation and temperature recovery. Therefore, the gas production rate of positive rhythm was higher than that of the uniform and reverse rhythms, while the reverse rhythm was economically more suitable in the later stages of the production. Furthermore, the gas and water production rates decreased with the increase in the permeability contrast. The number of composite rhythmic layers negligibly affected the gas production rate, while it significantly affected the hydrate saturation distribution, indicating an increasing hydraulic connectivity in the lateral direction that may lead to water breakthrough. Moreover, the rhythmic structures significantly affected the gas production rate and the economic feasibility, and controlled the developed depth of high hydraulic connectivity. Therefore, minor and large seepage pathways could form in a complex rhythm reservoir. • Economic feasibility varies with the expansion of the hydrate dissociation region. • Reverse rhythms are more economical than positive ones in later production stages. • The number of composite rhythmic layer negligibly affected the gas production rate. • The rhythmic structure controls the development of high hydraulic connectivity. • Depth of high hydraulic connectivity occurs in high permeability layers. [ABSTRACT FROM AUTHOR]