nitrogen contents
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Author(s):  
Eisa Ebrahimi ◽  
Hossein Asadi ◽  
Mohammad Rahmani ◽  
Mohammad Bagher Farhangi ◽  
Afshin Ashrafzadeh

Abstract Natural and anthropogenic factors influence the entry of pollutants into surface waters and their accumulation in aquatic ecosystems. This study aimed to investigate precipitation and sediment concentration on the outflow of different forms of phosphorus (P) and nitrogen (N) in three primary land-use types along the Pasikhan River, the biggest river entering the Anzali Wetland in the Southern Caspian sea. Water sampling was performed on a monthly basis during the time bracket of 2017–2018. Different forms of P including total, soluble, particulate, total reactive, and dissolved reactive, and total Kjeldahl N, soluble N, particulate N, and were determined in the water samples. Total phosphorus and total Kjeldahl nitrogen contents lay within the range of 2.2–4.7 and from 0.14 to 0.33 mg l−1, respectively, downstream of the river. The highest monthly outflow of P from the watershed at the Agriculture station was recorded in October. Substantial conformity was found between the monthly trends of and and the trend of precipitation. The results indicated that sediment load intensified after an increase in the rainfall rate, leading to elevated N and P concentrations in the river water, mainly as particulate phosphorus and soluble nitrogen. It can also be inferred from the result that the concentration of N and P is directly related to the sediment concentration increase due to the rainfall. Increasing levels of nutrients such as N and P in the Pasikhan River can cause eutrophication in the Anzali Wetland, which needs conservative measures for reducing these elements' dynamic in the watershed.


2022 ◽  
Vol 10 (1) ◽  
pp. 53
Author(s):  
Sathy A. Naidu ◽  
Kandasamy Kathiresan ◽  
Jeffrey H. Simonson ◽  
Arny L. Blanchard ◽  
Christian J. Sanders ◽  
...  

Differences in grain size, total organic carbon (OC), total nitrogen (TN), OC/TN ratios, and stable isotope (δ13C and δ15N) were assessed in sediments from areas covered by mangrove and saltmarsh vegetation within Pichavaram estuary (Southeast India). The mean percentage contents of silt and clays (70 vs. 19%), OC (5.7 vs. 2.0%), and TN (0.39 vs. 0.14%) were consistently higher in the mangrove as compared to those observed in the saltmarsh tidal zone. These differences may obey the higher deposition and retention of fine particles in the presence of a mangrove root system that may facilitate the accumulation and preservation of organic matter within these sedimentary systems. Further, higher OC and TN contents were associated to higher terrestrial or mangrove-derived organic matter contribution with lighter δ13C signatures (−26.0‰) in both sedimentary tidal zones, whereas lower OC and TN contents were associated to heavier δ13C signatures. This study is in agreement with previous studies which indicate that the presence of wetland vegetation may increase the carbon and nutrient storage capacity within estuarine ecosystems, highly relevant information for the establishment of further conservation strategies for blue carbon ecosystems at global scales.


Agro-Science ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 103-113
Author(s):  
C.B. Okebalama ◽  
C.A. Igwe ◽  
A.O. Onunwa

Soil organic carbon (SOC) and total soil nitrogen (TSN) dynamics have both pedological and agronomic basis. Knowledge of their retention within aggregate hierarchies of varying soil textures as influenced by land use change is limited. The capacity of loam (L), clay loam (CL), sandy loam (SL) and sandy clay loam (SCL) soils to retain SOC and TSN in water-stable aggregate (WSA) at 10-cm intervals of 0-30 cm topsoil depths under cultivated and bushfallow/ uncultivated systems was investigated. The soils showed high dispersion ratio and great variations in aggregate silt and clay indices (CL > L > SCL > SL) under both land uses. Across soil depths, the uncultivated CL, SL and SCL soils had moderate to high > 2.00 mm WSA whose reduction due to cultivation impact was more pronounced in SL than in CL soil. Across soil depths and land uses, SOC content seemed higher in the macro- (> 0.50 mm) than in the micro- (< 0.50 mm) aggregates of all the soils while the reverse marked aggregate TSN content in almost all the soils. Cultivation mostly reduced macro-aggregate-associated SOC and TSN in L > CL > SL and in L > SL > CL > SCL soils, respectively. However, cultivation showed no reduction influence on micro-aggregate-associated SOC of all the soils. Cultivation-related reduction in micro-aggregate-associated TSN was more pronounced in the generally more ‘clayey’ CL and SCL than the L and SL soils. So, the potential of bush-fallowing to enhance micro-aggregateassociated TSN storage and stabilization against adverse influence of cultivation depends on soil texture.


Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7568
Author(s):  
Emmanouil Tsochatzis ◽  
Ida Elizabeth Berggreen ◽  
Francesca Tedeschi ◽  
Konstantina Ntrallou ◽  
Helen Gika ◽  
...  

Polystyrene (PS) is a plastic polymer extensively used for food packaging. PS is difficult to decompose and has low recycling rates, resulting in its accumulation in the environment, in the form of microplastic particles causing pollution and harming oceans and wildlife. Degradation of PS by mealworms (Tenebrio molitor) has been suggested as a possible biological strategy for plastic contamination; however, the biodegradation mechanism of PS by mealworms is poorly understood. It is hypothesized that the gut microbiome plays an important role in the degradation of PS by mealworms. This study carried out a comparative analysis of the gut microbiome of Tenebrio molitor larvae under different feeding strategies, and of the formation of degradation compounds (monomers, oligomers). A diet of bran:PS at 4:1 and 20:1 ratios was tested. The diet with the low ratio of bran:PS led to the presence of higher amounts of these compounds, compared to that with the high ratio. In addition, it was demonstrated that the addition of H2O significantly improved the biodegradation of PS monomer and oligomer residues, which could be identified only in the frass. The protein and nitrogen contents in insects’ biomass and frass varied amongst treatments. The diets resulted in differences in the gut microbiota, and three potential bacterial strains were identified as candidates involved in the biodegradation of PS.


Author(s):  
Boubacar M. Moussa ◽  
Laouali Abdou ◽  
Salamatou Abdourahamane Illiassou ◽  
Ali Mahamane

In the eastern Niger, vegetable crops such as lettuce are cultivated along the Komadougou Yobé river and near Lake Chad. Insecurity linked to terrorist groups prevents the exploitation of these areas and leads population to explore other lands. This study aims to find out whether sub-arid soils have in some places potentialities that can allow lettuce cultivation. A pedological survey was first carried out in the study area and some physicochemical soil parameters were analyzed. Then, a randomized experimental design with three cultivars (“Blonde de Paris”, “Iceberg Tahoma”, and “Iceberg edem”) and three replicates was carried out on soils which present favorable conditions for vegetable crops. The lettuce fresh mass was determined at harvest. The results show a significant influence of the geomorphological gradient on texture classes, nitrogen contents, pH values, cation exchange capacity and level of exchangeable bases. The lowland soils are more apt for vegetable crops like lettuce. The mean of lettuce fresh mass obtained for the three cultivars is 4.8±0.5 kg.m-². Iceberg Eden records the highest values and seems well adapted to eastern Niger.


Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1325
Author(s):  
Yitao Cai ◽  
Zhengqi Cao ◽  
Fei Liu ◽  
Kan Li ◽  
Long Li ◽  
...  

Most of the diamond deposits in China are in the North China Craton. In addition to gem diamonds in kimberlite, a large number of microdiamonds have also been discovered in alkaline dolerites. These microdiamonds show very different characteristics from those recovered in kimberlite. Here, we report the morphology, colour, nitrogen contents, and carbon isotopic compositions of the diamonds recovered from the alkalic dolerites in eastern China. The microdiamonds are mainly cube and rhombic dodecahedron with diameters of 0.2 to 0.6 mm. Infrared spectrum analysis shows that these microdiamonds are mostly type Ib with a small amount of type Ia. The Y centre is obvious in type Ib diamond. Modelling mantle residence times for the IaAB diamonds is about 550 Ma. Nitrogen contents of the diamonds range from 4.5–503 ppm, with a median value of 173 ppm. The total δ13C range of the microdiamonds varies between −18.6 and −21.1‰ and are similar to those of ophiolite diamond.


Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1277
Author(s):  
Jianglong Pu ◽  
Haiping Zhang ◽  
Min Wang ◽  
Kyle Rogers ◽  
Hongmei Wang ◽  
...  

Light cycle oil (LCO) is one of the major products in Fluid catalytic cracking (FCC) processes, and has drawbacks such as high aromatics, sulfur, and nitrogen contents, and low cetane number (CN). Hydro-upgrading is one of the most typical processes for LCO upgrading, and alumina-zeolite (AZ) is an effective hydrotreating catalyst support. This paper examined the effects of different bimetallic catalysts (CoMo/AZ, NiMo/AZ, and NiW/AZ) supported by AZ on hydro-upgrading of both model compounds and real LCO. CoMo/AZ preferred the direct desulfurization (DDS) route while the NiMo/AZ and NiW/AZ catalysts favored the desulfurization route through hydrogenation (HYD). The presence of nitrogen compounds in the feed introduced a competitive adsorption mechanism and reduced the number of available acid sites. Aromatics were partially hydrogenated into methyltetralines at first, and then further hydrogenated, cracked, and isomerized into methyldecalins, monocyclic, and methyltetralines isomers. CoMo/AZ is the best hydrodesulfurization (HDS) catalyst for the model compounds at low H2 pressure (550 psi) and for LCO at lower temperature (573 K), while NiMo/AZ performs the best for LCO at higher temperature (648 K). NiMo/AZ is the best hydrodenitrogenation (HDN) catalyst for LCO. The hydrodearomatization (HDA) performances of NiMo/AZ and NiW/AZ improved significantly and overwhelmingly higher than that of the CoMo/AZ when the H2 pressure was increased to 1100 psi.


Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Wei Wang ◽  
Yue Ma ◽  
Shuyuan Li ◽  
Changtao Yue ◽  
Jiancun Gao

Oil shale samples from Longkou City, Shandong Province, China, were pyrolyzed in a fixed bed reactor at retorting temperature varied from 400 to 550°C under nitrogen atmosphere with heating rate of 15°C/min. The influence of retorting temperature on the yield and characteristics of shale oil and retorting gases were determined. It was observed that the oil yield increased to the maximum value, 15.68 wt%, as the retorting temperature increased from 440 to 550°C. And increasing retorting temperature improved also gas yields, but reduced the char yield. The contents of H2, CO2, and CH4 in the retorting gas increased with the rising of retorting temperature. The ratio of alkane/alkene hydrocarbon (C1-C5) decreased because of the secondary cracking reactions of gas phase in the high temperature. The carbon and nitrogen contents of shale oil increased with increasing retorting temperature, while those of hydrogen and oxygen decreased. The sulfur content was not significantly affected by the retorting temperature. In addition, the shale oil obtained from 550°C had the lowest aromatic content, 25.12 wt%, and the highest saturate content, 50.03 wt%, compared to the other retorting temperatures due to the cracking of aliphatic compounds. The alkanes with 8-34 carbons and alkenes with 8-27 carbons were detected in the shale oil. The concentration more than 20 mg/goil was C23-C30 in the range of 400-550°C. The total content of n-alkanes decreased to 369.25 mg g-1oil, and that of n-alkene reached the maximum value at 550°C, 181.62 mg/goil, with the rise of retorting temperature. It was demonstrated that the higher temperature was beneficial to promoting the reaction of aromatization, dehydrogenation, fraction, and other reactions in the pyrolysis process.


2021 ◽  
Vol 2021 (10) ◽  
pp. 1299-1303
Author(s):  
V. M. Blinov ◽  
E. I. Lukin ◽  
E. V. Blinov ◽  
M. A. Samoilova

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5744
Author(s):  
Jiri Houska

Amorphous Si-B-C-N alloys can combine exceptional oxidation resistance up to 1500 °C with high-temperature stability of superior functional properties. Because some of these characteristics require as high N content as possible, the maximum achievable N content in amorphous Si-B-C-N is examined by combining extensive ab initio molecular dynamics simulations with experimental data. The N content is limited by the formation of unbonded N2 molecules, which depends on the composition (most intensive in C rich materials, medium in B rich materials, least intensive in Si-rich materials) and on the density (increasing N2 formation with decreasing packing factor when the latter is below 0.28, at a higher slope of this increase at lower B content). The maximum content of N bonded in amorphous Si-B-C-N networks of lowest-energy densities is in the range from 34% to 57% (materials which can be grown without unbonded N2) or at most from 42% to 57% (at a cost of affecting materials characteristics by unbonded N2). The results are important for understanding the experimentally reported nitrogen contents, design of stable amorphous nitrides with optimized properties and pathways for their preparation, and identification of what is or is not possible to achieve in this field.


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