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Nitrification inhibitors (NI) are widely used in fertilization to modify nitrogen (N) transformation in soil for matching crop N requirement and reducing N loss to environments. However, the effects of major NI products in China o...
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Nitrification inhibitors (NI) are widely used in fertilization to modify nitrogen (N) transformation in soil for matching crop N requirement and reducing N loss to environments. However, the effects of major NI products in China on inorganic N transformation in purple soil are poorly quantified. Therefore, incubation experiment was carried out to study the effects of major NI products including Entrench (En), 3,4-dimethylpyrazole phosphate (DMPP) and dicyandiamide (DCD) on inorganic N transformation in typical purple soil which is the predominant soil in Sichuan Basin, China. With the same incubation condition (soil moisture: 70% of water hold capacity at 25℃), the contents of ammonium nitrogen (NH_4~+-N), nitrite nitrogen (NO_3~--N), and pH value were measured, and then the apparent nitrification rate and inhibitory rate of the three nitrification inhibitors were calculated. Results showed that the NI can significantly reduce the acidification rate of the purple soil. And a strong nitrification process was showed in the soil without nitrification inhibitors (CK), with 81.4% of NH_4~+-N disappearing from the mineral nitrogen pool during the whole incubation period of 100 days. Compared with CK treatment, addition of NI products resulted in a reduced disappearance of NH_4~+-N by 9.8% for En, 24.6% for DMPP and 26.1% for DCD, respectively. The nitrification process of nitrogen in soil was obviously inhibited by NI products, with the inhibition rate of 7.1% to 95.8% for DMPP and of 3.8% to 97.2% for DCD, respectively. Thus, the nitrification process was delayed by up to 30 days for these two treatments. The inhibition effect of nitrification process by En product was less than that of DMPP and DCD. Under the recommendation rate of NI products, the nitrification inhibition rates were in the order of DCD (5% w/w)>DMPP (1% w/w)>En (2.4% w/w). We concluded that all the major NI products in China could significantly inhibit the process of nitrification in purple soil. While, DMPP and DCD are superior to En product in maintaining NH_4~+-N, inhibiting nitrification process and reducing acidification of the purple soil.
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The morphology of fuel nitrogen in coal and its fate during pyrolysis and the nitrogen species including N_2, HCN and NH_3 during coal pyrolysis and gasification have been investigated to clarify the evolution mechanism of fuel ni...
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The morphology of fuel nitrogen in coal and its fate during pyrolysis and the nitrogen species including N_2, HCN and NH_3 during coal pyrolysis and gasification have been investigated to clarify the evolution mechanism of fuel nitrogen in heat treatment process. Experimental results show that the morphology of coal nitrogen in the studied Chinese raw coals generally include pyrrolic nitrogen (N-5), pyridinic nitrogen (N-6), quaternary nitrogen (N-Q) and nitrogen-oxide (N-X). Generally, nitrogen in char is transformed to volatile and more stable components during pyrolysis. Char-N is the major source of NOx precursors during temperature programmed pyrolysis in 600-800℃ . N-5 and N-X in char is converted to HCN first, and HCN is then hydrogenated to NH_3. N-Q in char is the main source of nitrogen gas. The major nitrogenous gas products during rapid coal pyrolysis are N2, HCN and NH_3, amongst which N_2 is dominant. The yields of N2 and NO_x precursors, such as HCN and NH_3, increase with increased pyrolysis temperature. The major gaseous nitrogenous products during coal gasification in steam include HCN, NH_3 and N_2. H_2O is the main source of the groups containing hydrogen, which not only participates in the reaction as a gasification agent, but also has catalysis on the reaction.
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摘要 :
The morphology of fuel nitrogen in coal and its fate during pyrolysis and the nitrogen species including N2, HCN and NH3 during coal pyrolysis and gasification have been investigated to clarify the evolution mechanism of fuel nitr...
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The morphology of fuel nitrogen in coal and its fate during pyrolysis and the nitrogen species including N2, HCN and NH3 during coal pyrolysis and gasification have been investigated to clarify the evolution mechanism of fuel nitrogen in heat treatment process. Experimental results show that the morphology of coal nitrogen in the studied Chinese raw coals generally include pyrrolic nitrogen (N-5), pyridinic nitrogen (N-6), quaternary nitrogen (N-Q) and nitrogen-oxide (N-X). Generally, nitrogen in char is transformed to volatile and more stable components during pyrolysis. Char-N is the major source of NOx precursors during temperature programmed pyrolysis in 600-800°C. N-5 and N-X in char is converted to HCN first, and HCN is then hydrogenated to NH3. N-Q in char is the main source of nitrogen gas. The major nitrogenous gas products during rapid coal pyrolysis are N2, HCN and NH3, amongst which N2 is dominant. The yields of N2 and NOx precursors, such as HCN and NH3, increase with increased pyrolysis temperature. The major gaseous nitrogenous products during coal gasification in steam include HCN, NH3 and N2. H2O is the main source of the groups containing hydrogen, which not only participates in the reaction as a gasification agent, but also has catalysis on the reaction.
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Organic waste materials like crop residues, well-decomposed cow dung, composts, and other rural and urban wastes are considered highly useful resources in enhancing soil fertility and also in build-up of soil organic matter. Organ...
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Organic waste materials like crop residues, well-decomposed cow dung, composts, and other rural and urban wastes are considered highly useful resources in enhancing soil fertility and also in build-up of soil organic matter. Organic matter decomposition provides plant nutrients in soil, which in turn increases crop productivity. Availability of nutrients and nitrogen (N) and phosphorus from organic waste materials is dependent upon the nature of organic residues, climatic conditions, and soil moisture activity. Keeping these factors in view, the present investigation was undertaken to study the transformation of N from different organic waste materials in two contrasting soils from an eastern India, subtropical region. The results showed that the amounts of ammo-niacal-N (NH_4-N), nitrate-N (NO_3-N), hydrolysable N (HL-N), and nonhydrolysable (NHL-N) were increased for up to 60 days of soil submergence and increased further with the increase (1% by weight of soil) of organic residue application. Considering the effect of various organic waste materials, it was found that the amounts of NH_4-N, NO_3-N, HL-N, and NHL-N were higher with the application of groundnut hull as compared to wheat straw and potato skin, which may be due to relatively narrow carbon:N ratio of groundnut (22:43) than that of wheat straw (62:84) and potato skin (71:32); however, the results showed that the release of NH_4-N. NO_3-N, HL-N, and NHL-N was in the order of groundnut hull > wheat straw > potato skin.
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摘要 :
Organic waste materials like crop residues, well-decomposed cow dung, composts, and other rural and urban wastes are considered highly useful resources in enhancing soil fertility and also in build-up of soil organic matter. Organ...
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Organic waste materials like crop residues, well-decomposed cow dung, composts, and other rural and urban wastes are considered highly useful resources in enhancing soil fertility and also in build-up of soil organic matter. Organic matter decomposition provides plant nutrients in soil, which in turn increases crop productivity. Availability of nutrients and nitrogen (N) and phosphorus from organic waste materials is dependent upon the nature of organic residues, climatic conditions, and soil moisture activity. Keeping these factors in view, the present investigation was undertaken to study the transformation of N from different organic waste materials in two contrasting soils from an eastern India, subtropical region. The results showed that the amounts of ammo-niacal-N (NH_4-N), nitrate-N (NO_3-N), hydrolysable N (HL-N), and nonhydrolysable (NHL-N) were increased for up to 60 days of soil submergence and increased further with the increase (1% by weight of soil) of organic residue application. Considering the effect of various organic waste materials, it was found that the amounts of NH_4-N, NO_3-N, HL-N, and NHL-N were higher with the application of groundnut hull as compared to wheat straw and potato skin, which may be due to relatively narrow carbon:N ratio of groundnut (22:43) than that of wheat straw (62:84) and potato skin (71:32); however, the results showed that the release of NH_4-N. NO_3-N, HL-N, and NHL-N was in the order of groundnut hull > wheat straw > potato skin.
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In laboratory-scale batch experiments, duckweed (Limna gibba)-based and algae-based wastewater containers have been monitored over 15 days in two experiments with different initial total nitrogen concentrations of 50 (experiment 1...
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In laboratory-scale batch experiments, duckweed (Limna gibba)-based and algae-based wastewater containers have been monitored over 15 days in two experiments with different initial total nitrogen concentrations of 50 (experiment 1) and 100 mg-N/L (experiment 2). Clear differences in environmental conditions were observed. High dissolved oxygen (DO) concentrations were observed in the algae-based, compared to duckweed-based, containers. In the algae-based containers the DO range was between 2.1 to 6.6 mg/L and 1.2 to 4.3 mg/L in experiment 1 and 2, respectively, whereas in the duckweed-based containers DO ranged between 1.1 to 3 mg/l and 0.5 to 2.1 mg/L. Higher pH values were measured in algae-based due to algal photosynthetic activity compared to duckweed-based containers where the duckweed mat prevented sunlight penetration and hence algal development.In algae-based containers, the pH range was 7.9 to 8.6 and 8.1 to 8.4 in experiments 1 and 2, respectively, and 7.3 to 7.5 and 7 to 7.6 in the duckweed-based containers. Depending on initial nitrogen concentrations, duckweed-based containers removed between 42
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摘要 :
In laboratory-scale batch experiments, duckweed (Limna gibba)-based and algae-based wastewater containers have been monitored over 15 days in two experiments with different initial total nitrogen concentrations of 50 (experiment 1...
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In laboratory-scale batch experiments, duckweed (Limna gibba)-based and algae-based wastewater containers have been monitored over 15 days in two experiments with different initial total nitrogen concentrations of 50 (experiment 1) and 100 mg-N/L (experiment 2). Clear differences in environmental conditions were observed. High dissolved oxygen (DO) concentrations were observed in the algae-based, compared to duckweed-based, containers. In the algae-based containers the DO range was between 2.1 to 6.6 mg/L and 1.2 to 4.3 mg/L in experiment 1 and 2, respectively, whereas in the duckweed-based containers DO ranged between 1.1 to 3 mg/l and 0.5 to 2.1 mg/L. Higher pH values were measured in algae-based due to algal photosynthetic activity compared to duckweed-based containers where the duckweed mat prevented sunlight penetration and hence algal development.In algae-based containers, the pH range was 7.9 to 8.6 and 8.1 to 8.4 in experiments 1 and 2, respectively, and 7.3 to 7.5 and 7 to 7.6 in the duckweed-based containers. Depending on initial nitrogen concentrations, duckweed-based containers removed between 42
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摘要 :
In laboratory-scale batch experiments, duckweed (Limna gibba)-based and algae-based wastewater containers have been monitored over 15 days in two experiments with different initial total nitrogen concentrations of 50 (experiment 1...
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In laboratory-scale batch experiments, duckweed (Limna gibba)-based and algae-based wastewater containers have been monitored over 15 days in two experiments with different initial total nitrogen concentrations of 50 (experiment 1) and 100 mg-N/L (experiment 2). Clear differences in environmental conditions were observed. High dissolved oxygen (DO) concentrations were observed in the algae-based, compared to duckweed-based, container. In the algae-based containers the DO range was between 2.1 to 6.6 mg/L and 1.2 to 4.3 mg/L in experiment 1 and 2, respectively, whereas in the duckweed-based containers DO ranged between 1.1 to 3 mg/L and 0.5 to 2.1 mg/L. Higher pH values were measured in algae-based due to algal photosynthetic activity compared to duckweed-based containers where the duckweed mat prevented sunlight penetration and hence algal development. In algae-based containers, the pH range was 7.9 to 8.6 and 8.1 to 8.4 in experiments 1 and 2, respectively, and 7.3 to 7.5 and 7 to 7.6 in the duckweed-based containers. Depending on initial nitrogen concentrations, duckweed-based containers removed between 42
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Nitrogen in high nitrogen steels (HNS) is supersaturated at high temperature and low nitrogen pressure, limiting its use as heat resistant steels and vacuum chamber material. Fe-18Cr-8Mn-N, Fe-15Cr-5Mn-5Ni-N, Fe-12Cr-N, Fe-20Cr-8M...
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Nitrogen in high nitrogen steels (HNS) is supersaturated at high temperature and low nitrogen pressure, limiting its use as heat resistant steels and vacuum chamber material. Fe-18Cr-8Mn-N, Fe-15Cr-5Mn-5Ni-N, Fe-12Cr-N, Fe-20Cr-8Mn-N, Fe-19Cr-15Mn-N, containing 0.276mass% to 0.910 mass% nitrogen were prepared by a pressurized induction melting furnace. Specimens were observed with a laser microscope in a high-temperature image heating system under 1 atm pure argon flow. For the sample of Fe-12Cr-N, the solid state precipitation of a compound was observed. The nitrogen gas was found to escape from the surface of the solid Fe-12Cr-0.276N steel sample first and after melting of the steel nitrogen bubbles were observed floating out from steel melt to the surface. The nitrogen release from solid HNS was in good accordance with the previous result obtained with TG/DTA measurements. For the sample of Fe-20Cr-8Mn-0.853N, a phase transformation and a sequential growth of precipitate was observed. No nitrogen release was observed for the sample Fe-19Cr-15Mn-0.576N but the aggregation and growth of nitrogen bubbles on the liquid Fe-19Cr-15Mn-0.910N surface was observed. Also for sample Fe-19Cr-15Mn-0.576N, during the melting and solidification, inclusion movement and crystal growth were observed. From these observations it was found that the behaviors of nitrogen release was related with the nitrogen content in HNS, heating rate and the alloy composition. These observations confirm that the in-situ observation is a powerful method to study the nitrogen behavior in HNS during heating and melting.
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摘要 :
Nitrogen in high nitrogen steels (HNS) is supersaturated at high temperature and low nitrogen pressure, limiting its use as heat resistant steels and vacuum chamber material. Fe-18Cr-8Mn-N, Fe-15Cr-5Mn-5Ni-N, Fe-12Cr-N, Fe-20Cr-8M...
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Nitrogen in high nitrogen steels (HNS) is supersaturated at high temperature and low nitrogen pressure, limiting its use as heat resistant steels and vacuum chamber material. Fe-18Cr-8Mn-N, Fe-15Cr-5Mn-5Ni-N, Fe-12Cr-N, Fe-20Cr-8Mn-N, Fe-19Cr-15Mn-N, containing 0.276mass% to 0.910 mass% nitrogen were prepared by a pressurized induction melting furnace. Specimens were observed with a laser microscope in a high-temperature image heating system under 1 atm pure argon flow. For the sample of Fe-12Cr-N, the solid state precipitation of a compound was observed. The nitrogen gas was found to escape from the surface of the solid Fe-12Cr-0.276N steel sample first and after melting of the steel nitrogen bubbles were observed floating out from steel melt to the surface. The nitrogen release from solid HNS was in good accordance with the previous result obtained with TG/DTA measurements. For the sample of Fe-20Cr-8Mn-0.853N, a phase transformation and a sequential growth of precipitate was observed. No nitrogen release was observed for the sample Fe-19Cr-15Mn-0.576N but the aggregation and growth of nitrogen bubbles on the liquid Fe-19Cr-15Mn-0.910N surface was observed. Also for sample Fe-19Cr-15Mn-0.576N, during the melting and solidification, inclusion movement and crystal growth were observed. From these observations it was found that the behaviors of nitrogen release was related with the nitrogen content in HNS, heating rate and the alloy composition. These observations confirm that the in-situ observation is a powerful method to study the nitrogen behavior in HNS during heating and melting.
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