Average Organic Carbon Content Research Articles

Seasonal Variation of Carbonaceous Species of PM10 Over Urban Sites of National Capital Region of India

The air quality of national capital region (NCR) of Delhi, India is becoming more severe day by day because of the anthropogenic activities. To get a better understanding of the ambient air quality of NCR-Delhi, the study of carbonaceous species in particulate matter (PM) is essential. PM10 samples were collected periodically from the three main urban sites (Faridabad; IGDTUW-Delhi; and CSIR-NPL Delhi,) of NCR-Delhi in the year 2015 to explore the possible sources of carbonaceous species [organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC)] in PM10. The annual average concentrations of PM10, OC, EC, and WSOC were estimated as 195 ± 121, 23.6 ± 14.4, 5.2 ± 4.0, and 15.5 ± 7.7 µg m−3, respectively, at Faridabad, whereas average concentrations of PM10, OC, EC, and WSOC were 274 ± 141, 30.8 ± 19.3, 9.4 ± 5.2, and 21.3 ± 14.3 µg m−3, respectively, at IGDTUW, Kashmiri Gate. Concentrations of PM10, OC, EC and WSOC were estimated as 209 ± 81, 26.0 ± 12.8, 7.9 ± 5.6 and 9.7 ± 5.9 µg m−3 at CSIR-NPL. During the study, a significant positive linear trend between OC vs. EC and OC vs. WSOC have been observed for these three sites as (R2 = 0.64 and R2 = 0.76 at Faridabad; R2 = 0.66 and R2 = 0.87 at IGDTUW-Delhi; and R2 = 0.79 and R2= 0.55 at CSIR-NPL), which indicates the common sources (vehicular emission and/or biomass burning) of carbonaceous aerosols over NCR-Delhi. All these carbonaceous species of PM10 shows seasonal variation with maxima during winter as well as post-monsoon and minima during monsoon seasons. 5 days backward trajectories of the air masses were calculated which shows the origination of pollutants from local sources along with long-range transport. Furthermore, the secondary and primary organic carbon (i.e., SOC and POC) in PM10 were also computed and reported.

A Study of Indoor Carbonaceous Aerosols and the Socio-Economic Parameters in a Rural Area of Himachal Pradesh, India

Solid Biomass Fuel (SBF) burning is one of major reasons for the indoor air pollution and high disease burden in rural areas of India. This study has made an effort to find out the association of carbonaceous aerosol (CA) emissions with the socio-economic factors in the households of a rural village, Baggi in Himachal Pradesh, India. Also, the emissions of Organic Carbon (OC) and Elemental Carbon (EC) were evaluated for different types and combination of fuel combustion for cooking and heating purposes. Enhanced average concentrations of OC (240 μg/m3) and EC (118.4 μg/m3) were found with sole biomass burning (wood) on the Chullah (traditional low-budget cookstoves) due to inefficient and incomplete combustion. Although, there was a significant reduction of 53% and 41% in OC and EC respectively when a combination of biomass and Liquefied Petroleum Gas (LPG) was used for cooking. With LPG, the concentrations of OC and EC significantly declined to as low as 38.1 μg/m3 and 31.6 μg/m3 respectively. Also, an excellent inter-relationship was identified between the socio-economic parameters such as the kitchen’s ventilation, education, financial status, etc. and CA emissions. In the house with very good ventilation (2 wide windows), the total CA emissions were as low as 86.7μg/m3. Also, the family members were educated and financially affluent. On the other hand, the total CA emissions were escalated by a significant 75.9% where the ventilation facility was extremely poor (small window and slit in the roof), the family was limitedly educated, and financial status lied below poverty line. On an average, the women in this village were found to spend 5 hours per day in the kitchen area. The socio-economic parameters are necessarily important towards the mitigation indoor air pollution and hence carbonaceous aerosols.

Geochemical characteristics of Chang 91 source rocks of upper Triassic Yanchang formation in Zhidan-Ansai area, Ordos Basin and its significance for tight oil exploration

The average total organic carbon (TOC) content of Chang 91 source rocks is 4.85%, and the main kerogen type is II1, and the average pyrolysis peak temperature is 452 °C in Zhidan-Ansai area, Ordos Basin. These show that Chang 91 source rocks have reached good to excellent level and peak hydrocarbon generation stage. Chang 91 source rocks were formed in semi-deep lacustrine sedimentary environments of fresh-brackish water and weak oxidation-reduction. The discovery of Chang 91 source rock extends the oil exploration field of Yanchang Formation, especially in Zhidan area, it is a favorable area for further exploration in Chang 9 reservoir.

Online measurement of carbonaceous aerosols in suburban Shanghai during winter over a three-year period: Temporal variations, meteorological effects, and sources

Carbonaceous aerosols have adverse effects on both human health and the climate. To understand the temporal variations and sources of carbonaceous aerosols, organic carbon (OC) and elemental carbon (EC) were measured hourly in suburban Shanghai in 2015–2017 during winter. The average OC concentrations were 7.34 ± 4.51 μgC/m3 in 2015, 7.16 ± 4.43 μgC/m3 in 2016, and 6.4 ± 3.22 μgC/m3 in 2017. The EC concentrations decreased significantly each year, with average concentrations of 3.82 ± 2.43, 2.91 ± 2.28, and 2.46 ± 1.88 μgC/m3, respectively, which caused the OC/EC ratio to increase from 2015 to 2017. Although the meteorological conditions differed each winter, there was a similar pattern of OC and EC diurnal variations, with concentrations peaking at 08:00 and 20:00, largely due to rush-hour vehicle emissions. A downward trend of EC/CO and EC/NO2 (mass ratios) but steady CO and NO2 concentrations from 2015 to 2017 revealed that the characteristics of primary vehicle emissions changed, and that less EC was emitted. Secondary organic carbon (SOC) and primary organic carbon (POC) were estimated with the minimum R2 (MRS) method. The hiemal SOC/OC values in suburban Shanghai were 19.2 ± 18.6% in 2015, 31.1 ± 18.6% in 2016, and 51.0 ± 21.4% in 2017, exhibiting an increasing trend. As the PM2.5 concentration increased (from 0 to 50 μg/m3 to 100–300 μg/m3), a decreasing SOC/OC ratio (from 43.6 ± 23.9% to 21.8 ± 17.7%) was observed over the three years, showing that primary emissions were the main contributors to carbonaceous aerosols on haze days. Case analysis of haze events further demonstrated that the primary sources of OC and EC were vehicle emissions. The contributions of biomass burning and coal combustion to carbonaceous aerosols became less important over the study period. This study highlights the importance of controlling vehicle emissions to reduce carbonaceous aerosol concentrations in the suburbs of the Chinese megacity, Shanghai.

Application of integrated formation evaluation and three-dimensional modeling in shale gas prospect identification

Identifying the shale gas prospect is crucial for gas extraction from suchreservoirs. Junggar Basin (in Northwest China) is widely considered tohave high potential as a shale gas resource, and the Jurassic, the mostsignificant gas source strata, is considered as prospective for shale gasexploration and development. This study evaluated the Lower JurassicBadaowan Formation shale gas potential combined with geochemical,geological, and well logging data, and built a three-dimensional (3D)model to exhibit favorable shale gas prospects. In addition, methane sorption capacity was tested for verifying the prospects. The Badaowan shalehad an average total organic carbon (TOC) content of 1.30 wt. % andvitrinite reflectance (Ro) ranging from 0.47% to 0.81% with dominatedtype III organic matter (OM). X-ray diffraction (XRD) analyses showedthat mineral composition of Badaowan shale was fairly homogeneous anddominated by clay and brittle minerals. 67 wells were used to identifyprospective shale intervals and to delineate the area of prospects. Consequently, three Badaowan shale gas prospects in the Junggar Basin wereidentified: the northwestern margin prospect, eastern Central Depressionprospect and Wulungu Depression prospect. The middle interval of thenorthwestern margin prospect was considered to be the most favorableexploration target benefitted by wide distribution and high lateral continuity. Generally, methane sorption capacity of the Badaowan shale wascomparable to that of the typical gas shales with similar TOC content,showing a feasible gas potential.

Temporal Variations and Characteristics of the Carbonaceous Species in PM2.5 Measured at Anmyeon Island, a Background Site in Korea

Routine measurements of carbonaceous species in PM2.5 inculidng organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and humic-like-substance carbon (HULIS-C) in PM2.5 were performed at Anmyeon Island (AI) to clarify the seasonal variation and carbonaceous aerosol concentrations at a background site in Korea between 2015 and 2016. The annual average OC and EC concentrations were 4.52±3.25 μg/m3 and 0.46±0.28 μg/m3, respectively, and there were no clear seasonal variations in OC and EC concentrations. The average concentrations of WSOC and water-insoluble organic carbon (WISOC) were 2.56±1.95 μg/m3 and 1.96±1.45 μg/m3, respectively, and their composition in OC showed high temporal variations. A low correlation between WISOC and EC was observed, while WSOC concentrations were highly correlated with secondary organic carbon concentrations, which were estimated using the EC tracer method. The results indicate that the formation of secondary organic aerosols is a major factor for the determination of WSOC concentrations in this region. HULIS-C was the major component of WSOC, accounting for 39–99% of WSOC and the average concentration was 1.88±1.52 μg/m3. Two distinct periods with high carbonaceous speciess in PM2.5 were observed and characterized by their OC/EC ratios. The high concentration of OC with high ratio of OC/EC was due to the influence of a mixture of emissions from biomass burning and secondary formation transported from outside AI. While, the high concentrations of OC and EC with low OC/EC ratio were related to local vehicular emissions.

Effects of cultivation history in paddy rice on vertical water flows and related soil properties

Soil properties, especially physical properties and macropore characteristics, are controlling factors for vertical water flow in paddy fields. However, the effects of paddy rice cultivation history on vertical water flows and related soil properties have been rarely studied. The objectives were to identify the differences in soil physical properties and macropore parameters and to reveal the effects of these soil properties on vertical water flow patterns in paddy fields under different cultivation times. In this study, soil physical properties in a very young paddy field (2 y, VYPF), a young paddy field (18 y, YPF), and an old paddy field (>100 y, OPF) were analyzed. Meanwhile, macropore parameters (resolution of 0.6 mm) and vertical water flow patterns in these fields were identified by computed tomography and dye tracing experiment, respectively. As cultivation history lengthened in paddy rice, the average content of soil clay and organic carbon in the 80 cm depth soil profile increased, as did the thickness and bulk density of the plow pan. Also, macroporosity, macropore area density, macropore number density, node density, macropore angle, and hydraulic radius significantly decreased as length of cultivation age increased. As a result, differences in these soil propeties affected vertical water flow in three studied paddy fields. Steady-state infiltration rates decreased significantly in accordance with the reduced saturated hydraulic conductivity of soil cores from the plow pan; median values were 9.76 cm d−1, 2.93 cm d−1, and 0.13 cm d−1 for VYPF, YPF, and OPF, respectively. A greater abundance and distribution of a dye tracer and a higher stained area ratio under the plow pan in younger paddy fields indicated that more obvious preferential water flows occurred in VYPF and YPF than in OPF. This implied that the conversion of farmland from upland field to paddy field resulted in greater use of irrigation water and also posed a risk of groundwater pollution through increased percolation. Therefore, a longer puddling time before planting paddy rice should be conducted in paddy fields (i.e. YPF and VYPF) with a short cultivation history, which can reduce water percolation by enhancing bulk density, reducing macropores, and lowering the saturated water conductivity of the plow pan.

Variation of indoor and outdoor carbonaceous aerosols in rural homes with strong internal solid fuel combustion sources

Organic carbon (OC) and elemental carbon (EC) are important components of particulate matter and contribute significantly to the health and climate impacts of aerosols. In this study, we evaluated indoor and outdoor OC and EC concentrations in the total suspended particle (TSP) contents and their seasonal variations in rural households with strong indoor solid fuel combustion sources. The 24-h average indoor TSP, EC and OC concentrations were 470 ± 256, 7.9 ± 10.9, and 75 ± 114 μg/m3 during the non-heating period and increased to 691 ± 287, 19 ± 9, and 192 ± 97 μg/m3 during the heating period, respectively. The seasonal differences were statistically significant (p < 0.05). The increments in OC and EC concentrations were larger in outdoor air than in indoor air. OC and EC were correlated, with more significant correlations in indoor air compared to outdoor air and stronger correlations during the heating period compared to the non-heating period. In winter, the total carbon (TC=EC+OC) mass fractions in TSP increased obviously, primarily because of coal burning for indoor environments.

Comparison of biomass burning tracer concentrations between two winter seasons in Krynica Zdr\xf3j

Biomass burning is one source of air pollution that emits soot, smoke, particulate matter, free radicals and other substances, affecting human health, air quality, cloud formation processes and climate change. During biomass burning, organic biomass burning tracers are emitted, such as levoglucosan and its isomers mannosan and galactosan, which are formed at temperatures above 300 °C during cellulose and hemicellulose pyrolysis. The objective of this research is the measurement of biomass burning tracer concentrations in PM10 samples in Krynica during two winter seasons from 01.12.2017 to 31.03.2018 and from 01.12.2018 to 26.03.2019. The average concentrations of organic carbon were 9.48 μg/m3 in the 2017/2018 season and 8.79 μg/m3 in the 2018/2019 season. The average concentration of levoglucosan in the PM10 samples in 2017/2018 was 137 ng/m3, while in 2018/2019, the average concentration reached 245 ng/m3. Levoglucosan was the dominant compound among the determined biomass burning tracers, accounting for 88.6% in 2017/2018 and 72.4% in 2018/2019. The conducted measurements show that the levoglucosan to mannosan ratio was equal to 10.5 and 3.9 in 2017/2018 and 2018/2019, respectively. The biomass smoke organic carbon was approximately 10.6% in 2017/2018 and 20.5% in 2018/2019. These results correspond to the contribution of biomass smoke to organic carbon, which was equal to 14.4% and 28.4% in the 2017/2018 and 2018/2019 seasons, respectively.

Long-range Transboundary Atmospheric Transport of Polycyclic Aromatic Hydrocarbons, Carbonaceous Compositions, and Water-soluble Ionic Species in Southern Thailand

ABSTRACT This study investigated atmospheric particulate matter (PM) with an aerodynamic diameter of < 2.5 µm (PM2.5) observed at the Prince of Songkla University (Phuket Campus) in southern Thailand. All samples (n = 75) were collected using MiniVol™ portable air samplers from March 2017 to February 2018. Carbonaceous aerosol compositions, i.e., organic carbon (OC) and elemental carbon (EC), water-soluble ionic species (WSIS), and polycyclic aromatic hydrocarbons (PAHs) in the PM2.5 samples were identified and quantified. We found that the average PM2.5 concentration was 42.26 ± 13.45 µg m–3, while the average concentrations of OC and EC were 3.05 ± 1.70 and 0.63 ± 0.58 µg m–3, respectively. The OC/EC ratio was in the range of 2.69–16.9 (mean: 6.05 ± 2.70), and the average concentration of 10 selected ions was 6.91 ± 3.54 µg m–3. The average concentration of SO42– was the highest throughout the entire study period (2.33 ± 1.73 µg m–3); the average contribution of SO42– to the major ionic components was 34%. Surprisingly, the average concentrations of NO3– and NH4+ were relatively low. The mean ratio of [NO3–]/[SO42–] was 0.33 ± 0.24. Strong positive correlation was found between K+ and both OC and EC (r = 0.90 and r = 0.93, respectively). It is also precious to highlight that biomass burning (BB) is the major source of OC, EC and K+, which multiple studies have confirmed that the role of K+ as a biomass marker. Results showed that BB episodes might play a major role in producing the observed high levels of OC. The relatively high abundance of both B[g,h,i]P and Ind suggests that motor vehicles, petroleum/oil combustion, and industrial waste burning are the primary emission sources of PAHs in the ambient air of Phuket. Interestingly, principal component analysis (PCA) indicated that vehicular exhausts are the main source of carbonaceous aerosol compositions found in the ambient air of Phuket, whereas the contributions of biomass burning, diesel emissions, sea salt aerosols and industrial emissions were also important.

Effect of land use patterns on size distributions and aggregates stability in the mountainous areas of north-western Himalayas, India

A study was conducted to assess the impact of different land uses and management on soil aggregate stability in sub-mountainous area of Jammu state, India. Soil samples were collected from five different land uses systems viz., forest, horticulture, agriculture, pasture and degraded lands from each of the five locations for surface (0-15cm) and sub-surface (15-30cm) of soil depth. Soil aggregate stability was determined by dry and wet sieving methods. Dry sieving was determined without immersion in water and wet sieving was immersion in water, respectively. Soil properties such as soil organic carbon (SOC), bulk density (BD) and soil pH were also determined. Average soil organic carbon (SOC) content was observed to be higher in pasture (6.65 g kg-1) followed by forest (6.50 g kg-1), horticulture (5.76 g kg-1), agriculture (4.88 g kg-1), and degraded land (4.47 g kg-1). Soil BD was observed significantly higher in degraded land than in other land use, which was further increasing in deeper soil profiles. Macro aggregates (>2 mm) were abundant (52.52-91.13%) in pasture soils while micro-aggregates (<0.25 mm) were abundant (23.39-35.51%) in agriculture lands. Mean weight diameter (MWD) decreased significantly with immersion in water for soil depth for various land use indicating that the soils were vulnerable to water erosion. The influence of cultivation was generally expressed by reduced water stability aggregates (WSA) of soil aggregates, hence rendering the soil more vulnerable to crusting and erosion processes. Mean weight diameter (MWD) was dominant in pasture in surface soil whereas subsurface soil was dominant in forest landuse systems. The MWD from dry structure stability (GMDd) and their corresponding wet Mean weight mean diameter (MWDw) were related significantly (r = 0. 0.999**). The difference in the MWD in dry condition and immersion in water reveals that for degraded land was subject to severe degradation compared to cultivated, agriculture and horticulture soil, while for pasture land was more degraded than forest soil. The vegetation grown soils were of better soil structural quality than degraded land or no scanty vegetation. To preserve good structure thereby reducing soil degradation, long term fallows or other farming practices that ensure maintenance of soil organic matter.

A high-time resolution study of PM2.5, organic carbon, and elemental carbon at an urban traffic site in Istanbul

Organic Carbon (OC) and Elemental Carbon (EC) were investigated on selected days between January 2017 and January 2018 in an urban area heavily impacted by traffic in Istanbul megacity. 300 PM2.5 samples were collected with a time resolution of 2 h during the daytime between 07:00–19:00. Nighttime samples were collected with a time resolution of 12 h between 19:00–07:00. Samples were collected for three weeks during the winter and one week during the spring, summer, and fall. The daily PM2.5 concentrations exceeded the standard of 35 μg m−3 29% of the time. Air quality was classified as fair (PM2.5>26.4 μg m−3) and unhealthy (PM2.5>39.9 μg m−3) 43% and 20% of the days, respectively. The annual average OC and EC were 11.3 ± 4.91 and 4.1 ± 1.16 μg m−3, respectively. Organic carbon showed strong seasonal variation with high concentrations during the heating season and low concentrations during the summer. Elemental carbon did not show strong seasonality due to the continuous influence of heavy traffic. Diurnal variations of OC and EC were characterized by high concentrations during the morning and evening rush hours, and low concentrations in the middle of the day due to the dilution effect of an increased mixing layer. Formation of secondary organic carbon was uncertain during the summer due to dilution and low primary organic carbon emissions. Concentrations heavily depended on surface wind speed. Average OC concentrations were 56–72% higher at wind speeds lower than 2 m s−1 compared to that at wind speeds higher than 3 m s−1 during fall and winter. Higher EC concentrations (15–56%) were observed at wind speeds higher than 3 m s−1, showing that in addition to traffic emissions, EC was transported from nearby areas. Continuous measurements of high time resolved OC and EC are necessary for the development and evaluation of air pollution mitigation strategies, particularly from combustion sources.

First Long-Term Study of Atmospheric New Particle Formation in the Suburb of Shanghai from 2015 to 2017

In this study, long-term continuous monitoring of atmospheric new particle formation was conducted from 2015 to 2017 in the Shanghai suburbs using a scanning mobility particle sizer (SMPS). Combined with meteorological parameters, gaseous pollutants, and PM2.5 chemical composition data, the characterization of new particle formation was analyzed. The results of data analysis showed there were 172 new particle formation (NPF) days in the Shanghai suburbs, accounting for 18.3% of the total effective days (942 d). Typical new particle formation days (Event) and new particle growth-shrinkage (Shrinkage) days were 150 d and 32 d, respectively. The frequency of NPF occurrence was the highest in spring and summer, followed by autumn and winter. Compared with non-new particle formation (Non-NPF) days, Event and Shrinkage days had higher temperature and wind speed, lower humidity, less rainfall, and stronger solar radiation. The ratio of Event days was the highest when the prevailing wind was southerly, southwesterly, or westerly, and when the air masses were mainly from the vegetation cover and agricultural planting areas in the Taihu Lake Basin. The prevailing wind directions for Non-NPF and Shrinkage days were northeasterly and easterly to southeasterly. On the Event days, SO2 and O3 were higher than that on the Non-NPF days, indicating gaseous sulfuric acid and photochemical reactions were key contributors to new particle formation. Higher PM10 concentration was detected on the Event days than on the Non-NPF days, which may be attributed to the photocatalytic reaction. All the pollutant concentrations were the lowest on Shrinkage days, except that of O3. The average concentrations of inorganic components of PM2.5, such as NH4+, SO42-, and NO3- were higher on Event than on Non-NPF days in fall, whereas the opposite results were observed in other seasons. The average concentration of organic carbon on Event days was higher than that on Non-NPF days in each season. The concentrations of PM2.5 components on Shrinkage days were the lowest. However, the ratio of organic carbon on Shrinkage days was higher than that on Non-NPF days in spring, summer, and winter. The higher ratio of organic carbon on the NPF days than on the Non-NPF days suggested an important role of organic matter in the formation and growth of new particles in the suburbs of Shanghai.

Dispersed trees on smallholder farms enhance soil fertility in semi-arid Ethiopia

IntroductionDispersed trees such as Oxytenanthera abyssinica (A. Rich.) and Dalbergia melanoxylon (Guill. & Perr.) which are objectively maintained or planted on farmland provide a significant contribution to soil fertility improvement. However, there was no quantitative information on the level of soil nutrient additions of these trees to the soil system.MethodsThis study was conducted on the farmers’ fields in Kafta Humera district, Tigray region (northern Ethiopia), where mature stands of O. abyssinica and D. melanoxylon trees exist. Radial distance-based soil sampling (under the canopy, near to canopy, and far from canopy) was adopted to quantify the role of these trees on soil fertility improvement. Soil parameters tested were soil reaction (pH), total nitrogen (TN), available phosphorus (AvP), electrical conductivity (EC), cation exchange capacity (CEC), and organic carbon (OC).ResultsThere was a negative linear relationship between the radial distance of the O. abyssinica tree trunk and soil TN, OC, CEC, and AvP contents but not for pH. Similarly, negative linear relationship between distance from D. melanoxylon and TN, OC, and AvP was obtained. The average total nitrogen (0.26% and 0.13%), available phosphorus (7.21 ppm and 6.37 ppm), and organic carbon (1.73% and 1.02%) contents were respectively higher under the tree canopies of O. abyssinica and D. melanoxylon compared with the adjacent open canopies. The amount of soil OC, TN, AvP, and CEC under O. abyssinica tree species was also significantly higher by 69%, 100%, 13%, and 42% compared to that of D. melanoxylon tree species. However, the amount of EC and soil pH was significantly lower by 57% and 19%, respectively.ConclusionIn general, O. abyssinica and D. melanoxylon added a significant amount of nutrients to the soil. Thus, retaining these important tree species on farmland played a positive role in replenishing soil fertility for resource-constrained households so as to reduce chemical fertilizer amendments.

The long-term performance of composited soil with feldspathic sandstone amendment on sandy soil and its effects on corn yield

To estimate the long-term performance and the optimal ratio of feldspathic sandstone with sandy soil, experiments with different ratios of feldspathic sandstone to sandy soil (0:1, 1:1, 1:2 and 1:5 v/v) was conducted. The physical properties as soil texture, water-stable aggregate (WR0.25) content, and the organic carbon content of the composited soil for 6 years, and corn yield for 9 years were determined. Our results showed that after the addition of feldspathic sandstone: (1) soil texture was notably improved, changing from sand loamy soil (1:2 and 1:5) to sand loam soil (1:1) and silt sand soil (1:1) over planting time; (2) content of water-stable aggregate (WR0.25) significantly increased: WR0.25 of treatments 1:1, 1:2 and 1:5 all increased (by 29.26, 31.47 and 11.56%, respectively) compared with that of treatment 0:1; (3) the organic carbon content of the composited soils increased with time in all treatments. After six years of planting, average organic carbon content in treatments 1:1, 1:2 and 1:5 were 1.64, 1.51 and 1.77 g/kg, respectively, which were higher than that of 0:1 treatment; and (4) among the three ratios, treatment 1:2 (12 984 kg/ha) had the highest corn yield, followed by treatment 1:1 (12 040 kg/ha) and 1:5 (11 301 kg/ha). In conclusion, with a good performance, 1:2 was the best ratio of feldspathic sandstone to sand in improving the sandy soil structure of the Mu Us Desert, China.

Geologic and geochemical characteristics of the Cambrian marine shale in the Tarim Basin of China and their implication for the prediction of shale-gas resources

Although the Cambrian marine shale in the Tarim Basin is usually considered to be the source rocks for overlying conventional reservoirs, its unconventional shale-gas potential has not yet been evaluated. To indicate the unconventional resource play potential and highlight more favorable zones, we conducted a comprehensive lithologic, petrophysical, and geochemical analysis of 228 drill core samples from 14 wells and 167 outcrop samples from eight geologic sections in the basin. The results indicate that the Cambrian marine shale was deposited in basinal and slope environments dominated by shale and siliceous shale. The average total organic carbon (TOC) content of the Є1xd (Xidashan) and Є2m (Moheershan) Formations ranges from 0.5% to 2.5%, and that of the Є1y (Yuertusi) Formation ranges from 1.0% to 7.0%. Phytoplankton is dominant in the Є1xd and Є2m Formations, whereas benthic algae are more prevalent in the Є1y Formation. The organic matter ranges in maturity from high to postmature. The shale consists of abundant meso- and macropores. The mineral matter is mostly composed of quartz ([Formula: see text] in most samples) followed by carbonate minerals, with minor contributions made by clay minerals ([Formula: see text]). The analysis of methane adsorption isotherm indicates a positive correlation between the gas and TOC content and a negative correlation between the gas content and burial depth implying the good adsorption capacity of the shale-gas play. Resource estimation of the Middle-Lower Cambrian indicates that the Yuli and Ruoqiang areas contain a potential [Formula: see text] of shale gas, and they are the most favorable zones for further exploitation.

Comparing the agrochemical properties of compost and vermicomposts produced from municipal sewage sludge digestate

The aim of this work was to investigate whether the agronomic traits of vermicompost prepared from partially stabilised sewage sludge digestate after thermophilic composting were more favourable than those of conventional compost. The effects of various additives (green waste, spent mushroom compost, wheat straw, biochar) were also tested after 1.5 months precomposting followed by 3 months vermicomposting with Eisenia fetida or by compost maturing. Vermicomposting did not result in significantly more intensive mineralisation than composting; the average organic carbon contents were 21.2 and 22.2% in vermicomposts and composts, respectively. Hence, the average total (N: 2.4%; P: 1.9%; K: 0.9%) and available (N: 160 mg/kg; P: 161 mg/kg; K: 0.8%) macronutrient concentrations were the same in both treatments. The processing method did not influence the organic matter quality (E4/E6) either. However, on average the concentration of the plant growth regulator kinetin was more than twice as high in vermicomposts.

Analysis of Total Organic Carbon Source Differences Between New and Old Cascade Reservoirs using Carbon and Nitrogen Isotopes

The ecological problems due to reservoir construction are causing unprecedented concern. To reveal the differences in organic carbon distribution characteristics and sediment sources of total organic carbon (TOC) between the old and new reservoirs, water samples, and sediment samples from reservoirs constructed in the three different periods of Miaowei, Gongguoqiao, and Dachaoshan were collected in November 2017. The temperature (T), dissolved oxygen (DO), TOC, redox potential (ORP), total nitrogen (TN), and total phosphorus (TP) of the water samples were measured. The isotopes 15N and 13C were used as indicators with IsoSource software to analyze the contributions of TOC sources and their source materials to the corresponding reservoir sediments, in order to explore the carbon cycle mechanism and evolution mode of reservoir. The results showed that the average concentrations of organic carbon in the waters of the Miaowei, Gongguoqiao, and Dachaoshan Reservoirs were 0.95 mg·L-1, 1.97 mg·L-1, and 4.64 mg·L-1, respectively. The range of organic carbon content in the corresponding sediments was 4.41-81.63 g·kg-1, 18.30-28.42 g·kg-1, and 9.16-14.46 g·kg-1, respectively. The cascade construction of the reservoirs resulted in a difference between the sediment sources of the new and old reservoirs and the surrounding recharge area, meaning that the TOC of the new and old reservoirs were significantly different. For the TOC of waterbodies, the difference between the thermodynamic state of water and dissolved oxygen indirectly affects the distribution trend of TOC. The sediments mainly reflect the influence of source elements, that is, the ability of the sedimentary environment to preserve organic matter was the main cause of the vertical distribution of DCS, MV, and GGQ sediments. In the evolution mode of cascade reservoir, the research shows that it can be preliminarily set as three stages. Firstly, due to the short age of MV, it is in the first stage and mainly accumulates the TOC from the upstream. GGQ is longer than the age of MV, and it is mainly used to decompose the upstream TOC, so it is defined as in the second stage. Finally, as an old reservoir, DCS mainly accumulates TOC sources around the reservoir, which can be regarded as the third stage.

The Vertical Distribution Characteristics of Carbon to Nitrogen Ratio in Soft Rock and Sand Compound Soil

This study takes the soft rock and sand compound ratio communities located in Fuping, Shaanxi Province as the research object. Four treatments of soft rock and sand volume ratios of 0:1 (CK), 1:5 (C1), 1:2 (C2) and 1:1 (C3) were selected to analyze the relationship between carbon-nitrogen ratio (C/N) of compound soil and the soil nutrient and texture. The soil organic carbon and total nitrogen content decreased with the increase of soil depth under different treatments. The average organic carbon content ranged from 1.45-2.70 g·kg-1 and the organic carbon content of 0-10 cm soil layer was significantly higher than 20-30 cm soil layer, compounding ratio had a significant effect on organic carbon. With the increase of volume fraction of soft rock, the organic carbon content of 0-10 cm soil layer was the highest in C3 treatment. The average value of total nitrogen was between 0.28-1.31 g·kg-1, and the total nitrogen content of 0-10 cm soil layer was significantly higher than that of 10-20 cm and 20-30 cm soil layer. In the 0-10 cm soil layer, the total nitrogen content of C3 treatment was significantly higher than other treatments, and the compound ratio and soil layer had significant effects on total nitrogen. The average value of C/N was between 1.72-5.92, which was the lowest at 0-10 cm, and the value decreased with the increase of the volume fraction of soft rock, and the treatment with C3 was the most significant. When the ratio of soft rock to sand was 1:1, it can promote the accumulation of carbon and nitrogen in the surface soil of 0-10 cm and enhance the decomposition of microorganisms.

Characteristics and sources of organic carbon in coastal and marine atmospheric particulates over East China

To understand the influences of emission sources, transport and environmental factors on the characteristics of organic carbonaceous aerosols in the marine area, organic carbon (OC) and water-soluble organic carbon (WSOC) were measured in atmospheric samples collected from the coastal region and over the Bohai and Yellow Seas from 2015 to 2016. Compared with the averages of 19.28 and 10.61 μg·m−3 in the coastal samples, the average concentrations of OC and WSOC decreased to 2.17 and 1.54 μg·m−3 in the marine aerosol samples, respectively. WSOC contributed 60% to OC in Qingdao, while 68.4% to OC over the ocean, suggesting that WSOC is likely influenced by the dissolved organic carbon (DOC) in surface seawater. The highest OC/EC ratios (6.56) were observed in the samples collected from the air masses originating from the north land source, indicating that OC mainly comes from anthropogenic sources. The OC concentrations in the air mass samples from marine sources were only 50% of those in the samples from terrestrial sources. A negative correlation between the WSOC and transport distance over the sea and decreased OC/EC ratios were observed, which indicated that the contribution of secondary organic carbon (SOC) to OC decreased during the transport from land to sea. OC increased by 88.5% under the influence of Asian dust, while WSOC did not exhibit substantial changes. The positive matrix factorization (PMF) model showed that anthropogenic sources were the major source of carbonaceous aerosols, contributing 70% of the OC in Qingdao. The positive correlation between OC and particulate matter (PM) suggested that the OC affected the air quality.