Average Organic Carbon Content Research Articles

Bulk density and organic carbon contents of soil pedons influenced by different tree species

Abstract. Bulk density and organic matter content of soil are important soil attributes used in predicting the productivity potentials of soil and overall soil quality. The distribution of soils bulk density and organic carbon in horizons of soil pedons under different three tree species (Hevea brasiliensis – rubber, Pentaclethra macrophylla – oil bean and Irvingia gabonensis – ogbono) in Owerri, Southeastern Nigeria were investigated. A random survey method was used in field sampling. In all, three profile pits were dug, one in each site. A total of 36 soil samples were collected and analyzed for the study. Samples were collected at different horizon levels (A, AB, Bt1 and Bt2). Three representative samples were collected from each horizon. Bulk density, organic carbon and other routine analyses were performed using routine laboratory techniques. Mean, coefficient of variation and correlation analyses were analyzed. From the results obtained bulk density increased with depth, ranging from 1.05-1.81 g cm-3 in the rubber plantation, 1.02-1.70 g cm-3 in ogbono plantation and 1.11-1.57 g cm-3 in oil bean plantation. Bulk density decreased with the increase the organic carbon content. However, mean bulk density values irrespective of tree species did not exceed critical limits ranging from 1.28 to 1.32 g cm-3 as appropriate. Organic carbon ranged from 0.06-0.89 g kg-1 in rubber plantation, 0.42-0.87 g kg-1 in ogbono plantation and 0.72-1.25 g kg-1 in oil bean plantation. The epipedal horizons contained higher organic carbon than the endo-pedal horizons. The average organic carbon contents of the pedons were lower than the critical value irrespective of the tree species. The oil bean plantation had higher organic carbon and total nitrogen than the ogbono and rubber plantation while the ogbono plantation contained higher available phosphorus than the other two plantations studied.

Characteristics of Carbonaceous Aerosol Pollution in PM2.5 in Xi'an

Mass concentration, seasonal variation and sources of organic carbon (OC), element carbon (EC), methanol-soluble organic carbon (MSOC), and seven carbon components (OC1-4, EC1-3) were detected by thermal-optical analysis of 353 PM2.5 samples in Xi'an in 2017. The results show that the average mass concentrations of OC, EC, and MSOC were (17.56±11.83), (4.08±2.95) and (11.10±6.77) μg·m-3, respectively. The seasonal trend of the OC concentration follows the order winter > spring > summer > autumn. The seasonal trend in EC concentration follows the order winter > spring≈autumn > summer. The average MSOC/OC value is 0.64±0.20. The highest value is observed in winter and the lowest in summer. The correlation between OC and EC is good in spring (r2=0.76), but the correlation is poor in winter (r2=0.43). These results indicate that the source of the carbon aerosols was different. The content of secondary organic aerosols was estimated by the EC tracing method. The average mass concentration of SOC accounted for 51.9%, 38.4%, 37.3% and 44.0% of OC in spring, summer, autumn, and winter, respectively. The main sources of carbonaceous aerosols were analyzed by principal component analysis. The results show that carbonaceous aerosols originate mainly from coal and vehicle emissions in Xi'an.

Effects of tillage and straw return on water-stable aggregates, carbon stabilization and crop yield in an estuarine alluvial soil

In China, the average soil organic carbon (SOC) content of cultivated land is 30% less than the world average. Therefore, cultivation management-induced changes in SOC dynamics are necessary, especially in estuarine alluvial islands, where the SOC stocks are limited. We studied the effect of different combinations of tillage, fertilization and straw return on C distribution in different soil aggregates and on crop yield on an estuarine alluvial soil in eastern China. Compared to conventional tillage, conservation tillage (no-tillage coupled with straw return) increased water-stable large macroaggregates (>2 mm) by 35.18%, small macroaggregates (2–0.25 mm) by 33.52% and microaggregates by 25.10% in the topsoil (0–20 cm). The subsoil (20–40 cm) also showed the same trend. Compared to conventional tillage without straw return, large and, small macroaggregates and microaggregates in conservation tillage were increased by 24.52%, 28.48% and 18.12%, respectively. Straw return also caused a significant increase in aggregate-associated carbon (aggregate-associated C). No-tillage coupled with straw return had more total aggregate-associated C within all the aggregate fractions in the topsoil. But the different is that conventional tillage with straw return resulted in more aggregate-associated C than conservation tillage in the subsoil. No-tillage combined with straw return (T8) produced the highest carbon preservation capacity (CPC) of macroaggregates and microaggregates in the topsoil. A considerable proportion of the SOC was found to be stocked in the small macroaggregates under both topsoil (74.56%) and subsoil (67.09%). The CPC was highest (19.17 g·kg−1) in small macroaggregates. However, no-tillage and straw return had less potential to sustain crop yield than did the conventional tillage practices; with the average rice and wheat yield correspondingly decreased by 10.63% and 7.82% in three years.

Estimation and Uncertainty Analysis of Secondary Organic Carbon Using 1 Year of Hourly Organic and Elemental Carbon Data

AbstractHourly particulate matter 2.5 organic carbon (OC) and elemental carbon (EC) ambient concentrations were measured from February 2012 to January 2013 at a suburban site in the city of Guangzhou, China. The major primary OC and EC sources at this site are vehicular exhaust and regional combustion sources. The annual average OC and EC concentrations (±1SD) were 7.30 ± 5.68 and 2.67 ± 2.28 μgC/m3, respectively. Taking advantage of this large data set of more than 7,000 measurements, we examined the diurnal variation dynamics of the primary OC‐to‐EC ratio ([OC/EC]pri), derived using the minimum R squared (MRS) method, which deploys an algorithm that calculates (OC/EC)pri by exploring the assumed independency between EC and secondary OC (SOC). The MRS‐derived hour‐by‐hour (OC/EC)pri was the lowest (1.8–2.0) for the morning hours while higher (2.4–3.0) for the afternoon and evening hours. Cumulative evidence from other pollutant measurements suggests that the increase in MRS‐derived (OC/EC)pri in the afternoon and evening was a result of SOC formation from photooxidation of precursors that covary with EC (e.g., vehicular exhaust) and thereby inflate (OC/EC)pri. We subsequently separate SOC into two categories based on their correlations with EC, that is, SOCa that covary with EC and SOCb that is unassociated with EC variations. SOCa and SOCb make comparable contributions to SOC, demonstrating that their separation is essential for a more accurate SOC estimation. Otherwise, SOCa would be mistakenly accounted as primary OC. This approach in estimating SOC may underestimate SOCa and subject to bias stemming from OC emissions from cooking and biomass burning.

Research on Organic Carbon and Elemental Carbon Distribution Characteristics and Their Influence on Fine Particulate Matter (PM2.5) in Changchun City

In order to understand the distribution characteristics of organic carbon (OC) and elemental carbon (EC) in PM2.5 in Changchun; China; PM2.5 samples were collected from April 2017 to December 2017 using the KC-120H particulate matter sampler; and the NIOSH 5040 method was used for determination. The results showed that the average concentration of PM2.5 in Changchun was 45.92 µg/m3 (45.92 ± 50.17), and the annual average concentrations of OC and EC ranged from 15.69 to 24.32 µg/m3 and from 1.38 to 2.33 µg/m3; respectively. The annual OC/EC ratio range was 8.08–15.44; with an average of 11.70. OC and EC concentrations in spring were the lowest; whereas higher levels of both OC and EC were found in winter. Significant correlations between OC and EC were found in the non-heating period; indicating that there was a consistent or similar source; whereas OC was non-significantly correlated with EC in the heating period; suggesting that contributions of OC were from unrelated combustion sources.

Comparative study of the methods for the determination of organic carbon and organic matter in soils, compost and sludge

The aim of this study was to compare the most commonly used methods for the determination of organic carbon (OC) and organic matter (SOM), and evaluate the capability of LOI (loss on ignition method) to estimate OC, using reference soils, compost and sludge as standards. The use of a titrimetric endpoint (adding phosphoric acid prior to titration) is more suitable for assessing the level of organic carbon in soils with low, medium, high and very high content. The use of a photometric endpoint is more appropriate for samples of medium and high carbon content. LOI 400 and LOI 450 may also be used for the determination of samples with a high organic content whereas LOI 450 - in the determination of samples with an average organic content. LOI 450 can be used to evaluate SOC in a wide range of organic matter concentrations (3-55%). Indirect assessment of the organic carbon content or organic matter using a correction coefficient is not very accurate for samples with average organic carbon content. Keywords: methods, organic carbon, organic matter, certified samples

三工河流域琵琶柴群落凋落物对土壤有机碳固定的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 三工河流域琵琶柴群落凋落物对土壤有机碳固定的影响 DOI: 10.5846/stxb201806301443 作者: 作者单位: 贵州大学动物科学学院,中国科学院植物研究所,贵州大学动物科学学院,贵州大学动物科学学院,贵州省草地技术试验推广站,贵州大学动物科学学院,贵州大学 作者简介: 通讯作者: 中图分类号: 基金项目: 贵州省科技厅-贵州大学联合基金项目（黔科合LH字[2017]7288号）；国家自然科学基金青年项目（31700390） Effects of litter on soil organic carbon fixation in Reaumuria soongorica communities in the Sangong River basin Author: Affiliation: College of Animal Science, Guizhou University,,,,,,College of Animal Science, Guizhou University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:土壤有机碳是土壤碳库的重要组成部分，对生态系统生产力和全球碳循环有着重要作用。采用凋落物收集器和DIRT法（添加和去除凋落物法）研究三工河流域两处不同琵琶柴群落凋落物的产量、现存量、凋落物处理对土壤有机碳的影响。结果表明：群落1和群落2的凋落物产量季节变化趋势相同，均呈"N "型变化，在10月份达到最大值，7月或8月份达到次大值。凋落物现存量随季节均呈现" W"型变化，在10月份达到最大值，最大值分别为30.65 g/m2和57.87 g/m2。土壤有机碳随土壤深度的增加均逐渐降低，群落1和群落2分别下降了61.73%-62.39%和18.24%-25.84%。与对照处理相比，去除凋落物处理（NL）的群落1和群落2土壤有机碳分别降低了6.97%和18.38%；添加凋落物处理（DL）的土壤有机碳分别增加了19.64%和13.66%；去除凋落物处理（NL）的群落1和群落2土壤有机碳储量分别为1007.36 kg/hm2和709.30 kg/hm2，添加凋落物处理（DL）的土壤有机碳储量分别为1197.88 kg/hm2和1010.78 kg/hm2。双因素方差分析表明群落1的土层深度和三种处理对土壤有机碳的交互作用不显著，群落2的交互作用显著。回归分析显示：土壤水分、电导率、pH、容重和温度是导致两琵琶柴群落土壤有机碳不同的主要生态因子。相对较高的土壤pH和盐分含量抑制了凋落物的分解，导致凋落物现存量较高、土壤有机碳含量低；相对较高的土壤含水量和较小的容重，有利于土壤生物的活性和土壤有机碳的矿化，导致土壤有机碳含量降低。 Abstract:Soil organic carbon is an important component of the soil carbon pool,and plays a key role in ecosystem productivity and the global carbon cycle. In this research,litter removal and detritus input treatment (DIRT) methods were used to study the litter productivity,litter amount,and effects of different litter treatments on the soil organic carbon in two Reaumuria soongarica communities in the Sangong River Basin. The results showed that the litter productivities of two communities had almost identical seasonal changes;they reached their second-maximum and maximum values in July (August) and October,and both showed "N" distributions. The litter amount also presented similar seasonal change trends;both showed "W" distributions,and reached their maximum values of 30.65 g/m2 and 57.87 g/m2 in October,respectively. The soil organic carbon content gradually reduced with soil depth;Community 1 and Community 2 decreased by 61.73%-62.39% and 18.24%-25.84%,respectively. The average soil organic carbon content of Community 1 and Community 2 was reduced by 6.97% and 18.38% by the litter removal treatment (no litter,NL),and increased by 19.64% and 13.66% by the litter treatment (double litter,DL),respectively. The soil organic carbon storage values of Community 1 and Community 2 were 1007.36 kg/hm2 and 709.30 kg/hm2 after NL treatment,and 1197.88 kg/hm2 and 1010.78 kg/hm2 after DL treatment,respectively. Two-way analysis of variance showed that the interaction of soil organic carbon between the soil depths and three litter treatments was significant in Community 2,but not Community 1. Regression analysis showed that soil properties were determinants of the differences in soil organic carbon between the two communities. The relatively high litter amount and low soil organic carbon content were attributed to the high soil pH and salt content, which inhibited litter decomposition. Otherwise,the relatively high soil water content and low soil bulk density promoted both soil organism activity and soil organic carbon mineralization,which led to the decrease in soil organic carbon content. 参考文献 相似文献 引证文献

Palynofacies and geochemical analyses of the Silurian Tanezzuft Formation, NC115 concession, Murzuq Basin, south-west Libya: Implications for source rock potential and palaeoenvironment

A palynofacies and organic geochemical investigation has been undertaken on 46 core and cuttings samples taken from seven wells drilled in the NC115 Concession, Murzuq Basin, south-west Libya. Most of the samples yielded marine and non-marine palynomorphs in a fair to good state of preservation, which together with palynological data have been used to confirm the age, determine the environment of deposition, and evaluate the petroleum source potential of the Tanezzuft Formation. The palynological assemblage recovered from the basal Hot Shale contains an abundance of acritarchs, chitinozoans and cryptospores, with some taxa, such as Plectochitina sp., Evittia remota, and Tetrahedraletes medinensis, indicating an early–mid Rhuddanian (early Llandovery) age for this unit. The deposits overlying the Hot Shale yielded diverse assemblages of palynomorphs, the occurrence of Angochitina qusaibaensis and Leiofusa banderillae in particular indicating a late Rhuddanian–Telychian (Llandovery) age. Two palynofacies associations have been identified. The Hot Shale palynofacies (PF-A) contains Type-II ≥ I kerogen, which is highly oil-prone and reflects a distal suboxic–anoxic sedimentary environment. The palynofacies of the overlying deposits of the Tanezzuft Formation (PF-B) is dominated by Type-II/III kerogen, which is both oil- and gas-prone, and indicates depositional conditions that range from distal dysoxic–oxic shelf to mud-dominated oxic shelf (distal shelf). Rock-Eval pyrolysis results indicate that the Hot Shale is organically-rich with an average total organic carbon (TOC) content 7.23 wt%, whereas the TOC of the overlying deposits averages 0.62 wt%. The organic matter in the Hot Shale has the capability of generating more liquid hydrocarbons than the rest of the formation, which lies within the early oil-maturity window. A simulated burial history for the NC115 Concession allowed the time and magnitude of hydrocarbon generation from the main Silurian Tanezzuft Formation source rock to be determined. Oil generation from this source rock took place during the Carboniferous/mid-Cretaceous period, whereas the maturation level for gas had not been reached at this stage.

Spatial heterogeneity and affecting factors of litter organic carbon and total nitrogen over natural spruce-fir mixed forests in northeastern China

Litter, as the basic carrier of nutrients, is a link between plants and soil in nutrient cycling and plays a major role in maintaining soil fertility and promoting material cycling and nutrient balance in forest ecosystems. The present study used geostatistics to investigate the spatial heterogeneity of organic carbon (OC) and total nitrogen (TN) in litter and their influencing factors, over four representative 1-ha natural spruce-fir mixed stands in Jilin Province, China. Our results showed that forest litter OC and TN varied in the four stands with an average OC concentration ranging from 378 to 453 g·kg−1 and average TN concentration ranging from 16.4 to 21.8 g·kg−1. The nugget-to-sill values were <25%, revealing that litter OC and TN had a strong spatial autocorrelation. Spatial distributions were estimated using ordinary kriging and showed a distinct strip and patch as the gradient changed. The fractal dimension of litter OC concentration was higher than that of litter TN. This indicated that litter OC had a more complex spatial pattern, whereas litter TN exhibited a better structure and stronger spatial dependence. Stand characteristics (i.e., species number, stem number, biodiversity indices, proportion of conifer species and stems), together with litter properties (i.e., litterfall, litter moisture content and total phosphorous concentration), affected the spatial variation in litter TN concentration, but they had no significant effects on litter OC. Therefore, this study demonstrated the feasibility of using geostatistics to predict litter nutrient concentrations at small scales and provided a theoretical basis for large-scale monitoring of biogeochemical cycles and disturbances in forest ecosystems.

Seasonal and annual trends of carbonaceous species of PM10 over a megacity Delhi, India during 2010–2017

PM10 samples were collected to characterize the seasonal and annual trends of carbonaceous content in PM10 at an urban site of megacity Delhi, India from January 2010 to December 2017. Organic carbon (OC) and elemental carbon (EC) concentrations were quantified by thermal-optical transmission (TOT) method of PM10 samples collected at Delhi. The average concentrations of PM10, OC, EC and TCA (total carbonaceous aerosol) were 222 ± 87 (range: 48.2–583.8 μg m−3), 25.6 ± 14.0 (range: 4.2–82.5 μg m−3), 8.7 ± 5.8 (range: 0.8–35.6 μg m−3) and 54.7 ± 30.6 μg m−3 (range: 8.4–175.2 μg m−3), respectively during entire sampling period. The average secondary organic carbon (SOC) concentration ranged from 2.5–9.1 μg m−3 in PM10, accounting from 14 to 28% of total OC mass concentration of PM10. Significant seasonal variations were recorded in concentrations of PM10, OC, EC and TCA with maxima during winter and minima during monsoon seasons. In the present study, the positive linear trend between OC and EC were recorded during winter (R2 = 0.53), summer (R2 = 0.59) and monsoon (R2 = 0.78) seasons. This behaviour suggests the contribution of similar sources and common atmospheric processes in both the fractions. OC/EC weight ratio suggested that vehicular emissions, fossil fuel combustion and biomass burning could be the major sources of carbonaceous aerosols of PM10 at the megacity Delhi, India. Trajectory analysis indicates that the air mass approches to the sampling site is mainly from Indo Gangetic plain (IGP) region (Uttar Pradesh, Haryana and Punjab etc.), Thar desert, Afghanistan, Pakistan and surrounding areas.

Assessment of unconventional shale gas potential of organic-rich Mississippian and Lower Pennsylvanian sediments in western Germany

The assessment of unconventional shale gas potential for the Mississippian Alum shales, the Kulm-Plattenkalk and the Lower Pennsylvanian Ziegelschiefer Formation in western Germany provides insight on how fluctuation in depositional environments has a significant role on lithofacies and shale gas potential. This paper uses a standard evaluation workflow for unconventional shale gas potential taking into account thickness, TOC content, mineral composition and brittleness, porosity and permeability data as well as thermal maturity. The average organic carbon content of the Lower and Upper Alum Shales reaches 2.4 wt% and 2.6 wt%, respectively and deposition took place in an oxygen-depleted marine environment, where hydrogen-rich type II kerogen was preserved in the sediments. In this study, the Kulm-Plattenkalk is investigated for the first time with regard to unconventional shale gas potential. The TOC content ranges between 0.22% and 6.85% (average: 2.45%) and carbonate content is 21% on average. In contrast, the Lower Pennsylvanian Ziegelschiefer Fm was deposited in a shallow marine suboxic to oxic environment with stronger terrestrial influence. TOC is 1.2% on average and the kerogen rich in terrestrial material has only a moderate original hydrocarbon generation potential. It should be noted that all samples are in the gas generation window and may hence have already lost about half of their original organic carbon content. A simple control of mineralogy on porosity and permeability was not evident, but a weak correlation was found between permeability and the average effective pore radii or slit widths. The Mississippian black shales have great similarity in terms of organic richness, thickness and quartz content with known gas shales of similar stratigraphic age from the US. However, differences with respect to burial and uplift history might have important influence on gas in place.

Carbonaceous components and major ions in PM10 from the Amazonian Basin

Air pollution mainly resulting from deforestation and agricultural activities has become one of the major concerns in the Amazonian Basin. A detailed analysis of the PM10 chemical composition is critical for devising pollution control measures and improving climate models. In this study, daily 24-h filter samples were collected and analyzed in different sites of the Amazon Basin between 2008 and 2016 (over 200 samples). The six sampling sites were classified into two groups, one in South Amazonia, a region with strong influence of land occupation, and another in a remote forest region to the North. The high mean concentrations of PM10 and the occurrences of extreme events at the Southern site denote air pollution episodes. High correlations between the temporal trends of PM10 and primary species linked to soil re-suspension and biomass burning highlight the contribution of these sources of air pollution in the region. Significant differences between PM10 in the South and North regions were observed, for which levels of 72.6 ± 66.5 μg m−3 and 8.9 ± 4.2 μg m−3, respectively. The average concentrations of organic carbon (OC) and elemental carbon (EC) in the aerosol were 5.81 ± 4.18 μg m−3, 2.43 ± 1.65 μg m−3 and 5.17 ± 5.54 μg m−3, 0.51 ± 0.41 μg m−3, respectively, for the Southern and Northern Amazonia sampling sites. The aerosol was largely composed of inorganic species in Southern Amazonia, whose carbonaceous matter accounted for 16% of the gravimetrically measured PM10. However, in the forest region, the contribution of carbonaceous species, mainly OC, accounted for >90% and remained more constant throughout the seasons. Na+ was the dominant water soluble ion in samples from the Southern region, followed by SO4−2, NO3−, Ca2+ and K+. High levels of carbonate (CC) were also observed for these samples. For the Northern region, SO4−2 was the dominant soluble ion, followed by K+ and NH4+. Some of these species exhibited a clear seasonal trend during the study period. This study provides a better understanding of the current state of air pollution in diversified Amazon basin sites.

Characteristics and Source Analysis of Atmospheric Carbonaceous Aerosols in the Cities of Hangzhou and Ningbo

To investigate the seasonal variations and sources of carbonaceous aerosols in the cities of Hangzhou and Ningbo, field PM2.5 sampling was conducted at four representative sites (two urban, one suburban, and one rural) in this region from December 2014 to November 2015. A thermal/optical carbon analyzer was employed to analyze both organic carbon (OC) and elemental carbon (EC) contents in PM2.5 by identifying eight different carbon fractions, including OC1, OC2, OC3, OC4+OPC, EC1-OPC, EC2, and EC3. Based on these fractions, OC and EC were defined as OC1+OC2+OC3+OC4+OPC and EC1+EC2+EC3-OPC, respectively; total carbon (TC) was calculated as the sum of OC and EC; and total carbonaceous aerosols (TCAs) were quantified via the sum of organic aerosols (OAs; converted from OC) and EC. The results showed the following. ①The annual average level of TC in this region was (14.3±4.1) μg·m-3, accounting for (26.2±6.5)% of the annual average PM2.5 concentration. The annual average OC and EC concentrations were (11.3±3.4) μg·m-3 and (3.0±0.9) μg·m-3, respectively. The highest TC level was observed in winter among the four seasons. ②The annual average TCA concentration in this region was (25.6±7.5) μg·m-3, contributing (42.2±10.0)% of PM2.5. In addition, secondary organic carbon (SOC) was also estimated by the commonly applied EC method. It was found that SOC contributed (41.1±5.5)% to OC on an annual average basis. ③The sources of carbonaceous aerosols were determined using the correlation between OC and EC, OC/EC mass ratio, and different carbon fraction characteristics. The annual average OC/EC ratio in this region was 4.7±1.7, which falls in the diagnostic ratio range for vehicular emissions, coal combustion, and biomass burning, indicating these sources are probably the major contributors of the regional carbonaceous aerosols. Moreover, a higher char-EC/soot-EC ratio was observed during winter and autumn at all sites, possibly implying the enhanced biomass burning activities during these two seasons.

Pollution Characteristics of Organic Carbon and Elemental Carbon in Atmospheric Aerosols in Beibei District, Chongqing

To study the pollution characteristics of atmospheric carbon aerosols, aerosol samples were collected via a cascade impactor (Andersen) from March 2014 to February 2015 in Beibei District, Chongqing. Organic carbon (OC) and element carbon (EC) were detected using a DRI 2001A carbon analyzer. The results showed that the annual average concentrations of OC and EC in PM2.1 were (16.3±7.6) and (1.8±0.7), respectively, and (25.0±9.6), and (3.2±1.3) μg·m-3, respectively, in PM9.0. The concentrations of both OC and EC were higher in winter and spring than in summer and autumn for PM2.1, whereas, for PM9.0, the concentration of OC was higher in summer and spring than in winter and autumn and that of EC was higher in winter and spring than in summer and autumn. The particle size distributions of OC and EC for the study year were analyzed, and it was found that those of OC were bimodal, with peaks in the size ranges of 0.43-0.65 μm for fine particles and 4.7-5.8 μm for coarse particles, and those of EC were trimodal, with peaks in the size ranges of 0.43-0.65 μm for fine particles and 4.7-5.8 μm for coarse particles and a concurrent significant peak in the particle size range of 2.1-3.3 μm. In addition, the correlations between OC and EC were analyzed and the SOC in PM2.1 was estimated. It was found that the average concentration of SOC was (6.3±5.9) μg·m-3, which accounted for 33.5%±22.6% of the OC concentration in Beibei District. Furthermore, OC and EC were significantly correlated. Finally, the pollution sources of atmospheric aerosols in Beibei were analyzed, and it was found that the pollution in Beibei mainly came from the exhaust gas of gasoline vehicles, biomass combustion, and coal combustion.

Influence of biomass burning on atmospheric aerosols over the western South China Sea: Insights from ions, carbonaceous fractions and stable carbon isotope ratios

Total suspended particle (TSP) samples were collected during a cruise campaign over the western South China Sea (SCS) from August to September 2014. Ten water-soluble ions (WSI), organic carbon (OC), elemental carbon (EC) and stable carbon isotope ratios of total carbon (δ13CTC) were measured. The average concentrations of total WSI, OC and EC were 7.91 ± 3.44 μg/m3, 2.04 ± 1.25 μg/m3 and 0.30 ± 0.22 μg/m3, respectively. Among the investigated WSI, sulfate (SO42−), sodium (Na+) and chloride (Cl−) were the most abundant species, accounting for 39.2%, 24.5% and 14.3% of the total mass of the WSI, respectively. Significantly positive correlations of OC and EC with non-sea-salt potassium (nss-K+), a tracer for biomass burning, suggest that biomass burning is the major source of carbonaceous aerosols. The values of δ13CTC ranged from −26.6‰ to −24.4‰ with an average of −25.3 ± 0.7‰. Based on the literature data of δ13CTC, back-trajectory analysis and satellite fire spots, we propose that C3 plant burning in Southeast Asia significantly contributes to carbonaceous aerosols over the western SCS. This is also supported by a good correlation between δ13CTC and the mass ratios of nss-K+/TC. Furthermore, high Cl− depletion (73 ± 23%) was observed in the aerosols over the western SCS. Given the neutralization of SO42− by ammonium (NH4+), excess nss-SO42- and oxalate (C2O42−) made major contributions to Cl− depletion in the samples strongly influenced by biomass burning. This study provides useful information to better understand the influence of biomass burning on atmospheric aerosols over the SCS.

Characteristics and Source Analysis of Carbonaceous Components of PM2.5 During Autumn in the Northern Suburb of Nanjing

In this study, PM2.5 samples were collected from October to November of 2015 in the northern suburb of Nanjing. The mass concentrations of organic carbon (OC), elemental carbon (EC), and levoglucosan in the samples were analyzed by thermal optical transmittance (TOT) and ion chromatography. The average concentrations of OC and EC were respectively (11.3±4.9) μg·m-3 and (1.1±0.9) μg·m-3. The average total carbon (TC) was 22.9%, and the OC/EC was 7.4. The quality concentrations of PM2.5, OC, EC, and SOC all reflected daytime features, and the correlation between OC and EC was better during the day than at night (correlation coefficients of 0.86 for day and 0.7 for night). By analyzing the mass concentrations of PM2.5, levoglucosan, and SOC, as well as the data of backward trajectories and fire point data, it was determined that the northern suburb of Nanjing is affected by the long-distance transportation of biomass from Hebei and other places from October 13-16. The correlations between levoglucosan and OC, EC, or SOC were significant (correlation coefficients of 0.78, 0.79, and 0.65, respectively), and the contribution of biomass combustion during sampling to OC was 21.9%.

Organic Carbon Distribution in the Bazhenov Horizon Rocks of the Western Siberian Megabasin

The distribution of organic carbon in the Bazhenov horizon rocks of the western Siberian sedimentary basin is investigated. The organic carbon concentration in rocks is estimated by the results of core analyses (4094 core analyses) and by the calculations of the core-log data correlations (48 500 measurements) according to the data of radiation and electrical loggings. The average content of organic carbon in the rocks of the Bazhenov and Tutleim (lower subformation) formation is 7.7%. The map of organic carbon concentrations in the sedimentary rocks of the basin is constructed. In the basin, Corg is distributed asymmetrically. The region of maximum Corg concentrations occupies the southwestern part of the internal area of the sedimentary basin. Silicites and biogene silica-enriched mixtites are enriched with organic matter most of all.

Analysis of the Characteristics and Sources of Carbonaceous Aerosols in PM2.5 in the Beijing, Tianjin, and Langfang Region, China.

PM2.5 samples from Beijing, Tianjin, and Langfang were simultaneously collected from 20 November 2016 to 25 December 2016, and the organic carbon (OC) and elemental carbon (EC) content in the samples were measured and analyzed. The pollution characteristics and sources of OC and EC in atmospheric PM2.5 for three adjacent cities were discussed. The average mass concentrations of OC in PM2.5 in Beijing, Tianjin, and Langfang were 27.93 ± 23.35 μg/m3, 25.27 ± 12.43 μg/m3, and 52.75 ± 37.97 μg/m3, respectively, and the mean mass concentrations of EC were 6.61 ± 5.13 μg/m3, 6.14 ± 2.84 μg/m3, and 12.06 ± 6.81 μg/m3, respectively. The average mass concentration of total carbon (TC) accounted for 30.5%, 24.8%, and 49% of the average mass concentration of PM2.5 in the atmosphere. The total carbonaceous matter (TCA) in Beijing, Tianjin, and Langfang was 51.29, 46.57, and 96.45 μg/m3, respectively. The TCA was the main component of PM2.5 in the region. The correlation between OC and EC in the three cities showed R2 values of 0.882, 0.633, and 0.784 for Beijing, Tianjin, and Langfang, respectively, indicating that the sources of urban carbonaceous aerosols had good consistency and stability. The OC/EC values of the three sampling points were 4.48 ± 1.45, 4.42 ± 1.77, and 4.22 ± 1.29, respectively, considerably greater than 2, indicating that the main sources of pollution were automobile exhaust, and the combustion of coal and biomass. The OC/EC minimum ratio method was used to estimate the secondary organic carbon (SOC) content in Beijing, Tianjin and Langfang. Their values were 10.73, 10.71, and 19.51, respectively, which accounted for 38%, 42%, and 37% of the average OC concentration in each city, respectively. The analysis of the eight carbon components showed that the main sources of pollutants in Beijing, Tianjin, and Langfang were exhaust emissions from gasoline vehicles, but the combustion of coal and biomass was relatively low. The pollution of road dust was more serious in Tianjin than in Beijing and Langfang. The contribution of biomass burning and coal-burning pollution sources to atmospheric carbon aerosols in Langfang was more prominent than that of Beijing and Tianjin.

THE GEOCHEMICAL CHARACTERISTICS OF THE OLIGOCENE – LOWER MIOCENE MENILITE FORMATION IN THE POLISH AND UKRAINIAN OUTER CARPATHIANS: A REVIEW

The principal source rocks in the Outer Carpathians are organic‐rich shales in the Oligocene to Lower Miocene Menilite Formation. The average total organic carbon (TOC) content in the Menilite Formation is 4–8 wt%; the maximum measured is 26 wt%. Organic matter (OM) is oil‐prone Type II kerogen derived mainly from algae and cyanobacteria which was deposited under euxinic conditions. The thermal maturity of the Menilite shales varies significantly within the Outer Carpathians, both vertically in relation to burial depth and laterally in different tectonic units, and increases from external to internal parts of the orogenic belt. Maturity in general ranges from immature to different phases of the “oil window” and up to the “gas window”.

Enhanced carbon-sulfur cycling in the sediments of Arabian Sea oxygen minimum zone center

Biogeochemistry of oxygen minimum zone (OMZ) sediments, which are characterized by high input of labile organic matter, have crucial bearings on the benthic biota, gas and metal fluxes across the sediment-water interface, and carbon-sulfur cycling. Here we couple pore-fluid chemistry and comprehensive microbial diversity data to reveal the sedimentary carbon-sulfur cycle across a water-depth transect covering the entire thickness of eastern Arabian Sea OMZ, off the west coast of India. Geochemical data show remarkable increase in average total organic carbon content and aerial sulfate reduction rate (JSO42−) in the sediments of the OMZ center coupled with shallowing of sulfate methane transition zone and hydrogen sulfide and ammonium build–up. Total bacterial diversity, including those of complex organic matter degraders, fermentative and exoelectrogenic bacteria, and sulfate-reducers (that utilize only simple carbon compounds) were also found to be highest in the same region. The above findings indicate that higher organic carbon sequestration from the water-columns (apparently due to lower benthic consumption, biodegradation and biotransformation) and greater bioavailability of simple organic carbon compounds (apparently produced by fermetative microflora of the sediments) are instrumental in intensifying the carbon-sulfur cycle in the sediments of the OMZ center.