Erosion as a natural process produces soils, which are very important natural resources for the fest land plant- and animal kingdoms. Loss of the soil cover reduces agricultural production, biodiversity, and the role ...Erosion as a natural process produces soils, which are very important natural resources for the fest land plant- and animal kingdoms. Loss of the soil cover reduces agricultural production, biodiversity, and the role of soil as a filter for infiltrating water to replenish the groundwater. It also threatens the food supplies. The knowledge of erosion rates of rocks and terrains is important for developing proactive measures to protect soils from erosion and loss. In this study, erosion rates of catchment areas were calculated based on dams’ catchment extensions and the sediment loads transported by flood flows into dams’ lakes. The study results show that the chemically, via floodwater, transported quantities of materials are negligible compared to the solid materials transported by the water. It calculates erosion rates ranging from 0.013 to 0.212 mm/yr (13 - 212 m/10<sup>6</sup> yr) for the different catchment areas. Erosion rates in Jordan are, generally, higher than those calculated for the different parts of the world ranging from 2.5 to 60 m/10<sup>6</sup> yr. This fact can be explained by the very steep topography, calcareous rock cover of the catchment areas and the barren rock exposures.展开更多
Indeed,polymeric materials have thrived in worldwide sectors over the last five decades due to their versatility and durability,to the point that we can no longer envisage a product that does not contain them.However,...Indeed,polymeric materials have thrived in worldwide sectors over the last five decades due to their versatility and durability,to the point that we can no longer envisage a product that does not contain them.However,many synthetic polymers that have been produced are mostly sourced from petroleum and coal as raw materials,making them environmentally incompatible because they cannot be integrated with what is a natural recycling system.One of the most important aspects of the transition to a circular bioeconomy(CBE)is the provision of more sustainable strategies for resource and waste management.Considering the environmental consequences associated with petroleum-based polymers(PBPs),natural biopolymers,originating from biomass,can be conceived as a promising solution to gradually replace the PBPs,and address,and resolve the potential challenges and prevailing research gaps in the PBPs.The biopolymers have significant advantages over PBPs in terms of low-cost/zero-cost precursors,environmental friendliness,and user-friendliness.The present review dissects the sources,synthesis pathways,structures,characterization,and employment of biopolymers and their composites in water and wastew-ater treatment applications via different scenarios.Furthermore,the CBE model framework proposes potential approaches to applying CBE principles in the wastewater management sector,with a heavy emphasis on not only technology but also organizational and societal reforms.To sum up,the reliance on biopolymers can be considered a crucial tool for assessing the global progress toward CBE,as well as future environmental management and planning.展开更多
Tree species diversity is assumed to be an important component in managing forest ecosystems because of effects on multiple functions or ecosystem multifunctionality.However,the importance of tree diversity in determi...Tree species diversity is assumed to be an important component in managing forest ecosystems because of effects on multiple functions or ecosystem multifunctionality.However,the importance of tree diversity in determining multifunctionality in structurally complex subtropical forests relative to other regulators(e.g.,soil microbial diversity,stand structure,and environmental conditions)remains uncertain.In this study,effects of aboveground(species richness and functional and structural diversity)and belowground(bacterial and fungal diversity)biodiversity,functional composition(community-weighted means of species traits),stand structure(diameter at breast height and stand density),and soil factors(pH and bulk density)on multifunctionality(including biomass production,carbon stock,and nutrient cycling)were examined along a tree diversity gradient in subtropical forests.The community-weighted mean of tree maximum height was the best predictor of ecosystem multifunctionality.Functional diversity explained a higher proportion of the variation in multifunctionality than that of species richness and fungal diversity.Stand structure-played an important role in modulating the effects of tree diversity on multifunctionality.The work highlights that species composition and maximizing forest structural complexity are effective strategies to increase forest multifunctionality while also conserving biodiversity in the management of multifunctional forests under global environmental changes.展开更多
The development of allometric biomass models is important process in biomass estimation because the reliability of forest biomass and carbon estimations largely depends on the accuracy and precision of such models.Nat...The development of allometric biomass models is important process in biomass estimation because the reliability of forest biomass and carbon estimations largely depends on the accuracy and precision of such models.National Forest Inventories(NFI)are detailed assessments of forest resources at national and regional levels that provide valuable data for forest biomass estimation.However,the lack of biomass allometric equations for each tree species in the NFI currently hampers the estimation of national-scale forest biomass.The main objective of this study was to develop allometric biomass regression equations for each tree species in the NFI of China based on limited biomass observations.These equations optimally grouped NFI and biomass observation species according to their phylogenetic relationships.Significant phylogenetic signals demonstrated phylogenetic conservation of the crown-to-stem biomass ratio.Based on phylogenetic relationships,we grouped and matched NFI and biomass observation species into 22 categories.Allometric biomass regression models were developed for each of these 22 species categories,and the models performed successfully(R^(2)=0.97,root mean square error(RMSE)=12.9t·ha^(–1),relative RMSE=11.5%).Furthermore,we found that phylogeny-based models performed more effectively than wood density-based models.The results suggest that grouping species based on their phylogenetic relationships is a reliable approach for the development and selection of accurate allometric equations.展开更多
A<sub>2</sub>FeCoO<sub>6-δ</sub> (A = Ca or Sr) is synthesized by the solid-state synthesis method and their specific heat capacities are evaluated at 40˚C using a heat flow meter. The effect ...A<sub>2</sub>FeCoO<sub>6-δ</sub> (A = Ca or Sr) is synthesized by the solid-state synthesis method and their specific heat capacities are evaluated at 40˚C using a heat flow meter. The effect of the A-cation size on the specific heat capacity of these compounds is observed. The specific heat capacity of Sr<sub>2</sub>FeCoO<sub>6-δ</sub> is found to be the highest, and that of Ca<sub>2</sub>FeCoO<sub>6-δ</sub> is the lowest while CaSrFeCoO<sub>6-δ</sub> shows the intermediate value. The specific heat capacity decreases with the decrease of the average A-site ionic radius, demonstrating the relationship between heat capacity and A-site ionic radius. The relationship between specific heat capacity and molar mass is also confirmed as the δ value decreases or molar mass increases from Ca<sub>2</sub>FeCoO<sub>6-δ</sub> to CaSrFeCoO<sub>6-δ</sub> to Sr<sub>2</sub>FeCoO<sub>6-δ</sub>.展开更多
This research assessed the environmental impact of cement silos emission on the existing concrete batching facilities in M35-Mussafah, Abu Dhabi, United Arab Emirates. These assessments were conducted using an air qua...This research assessed the environmental impact of cement silos emission on the existing concrete batching facilities in M35-Mussafah, Abu Dhabi, United Arab Emirates. These assessments were conducted using an air quality dispersion model (AERMOD) to predict the ambient concentration of Portland Cement particulate matter less than 10 microns (PM<sub>10</sub>) emitted to the atmosphere during loading and unloading activities from 176 silos located in 25 concrete batching facilities. AERMOD was applied to simulate and describe the dispersion of PM<sub>10</sub> released from the cement silos into the air. Simulations were carried out for PM<sub>10</sub> emissions on controlled and uncontrolled cement silos scenarios. Results showed an incremental negative impact on air quality and public health from uncontrolled silos emissions and estimated that the uncontrolled PM<sub>10</sub> emission sources contribute to air pollution by 528958.32 kg/Year. The modeling comparison between the controlled and uncontrolled silos shows that the highest annual average concentration from controlled cement silos is 0.065 μg/m<sup>3</sup>, and the highest daily emission value is 0.6 μg/m<sup>3</sup>;both values are negligible and will not lead to significant air quality impact in the entire study domain. However, the uncontrolled cement silos’ highest annual average concentration value is 328.08 μg/m<sup>3</sup>. The highest daily emission average value was 1250.09 μg/m<sup>3</sup>;this might cause a significant air pollution quality impact and health effects on the public and workers. The short-term and long-term average PM<sub>10</sub> pollutant concentrations at these receptors predicted by the air dispersion model are discussed for both scenarios and compared with local and international air quality standards and guidelines.展开更多
Intensive aeolian processes occur due to the scarcity of rainfall and lack of vegetation cover in arid regions. The study of recent surface sediments in arid areas is important for environmental assessments, evaluatio...Intensive aeolian processes occur due to the scarcity of rainfall and lack of vegetation cover in arid regions. The study of recent surface sediments in arid areas is important for environmental assessments, evaluation of natural resources, and land use planning. In this study, two areas were chosen as they show changes in lithology, environment and landforms. The two study areas are Al-Rawdatain in the northern part, and Al-Managish in the southern part of Kuwait. The current study aims to define the sedimentomorphic zones in these areas, with an emphasis on Quaternary geomorphological evolution by providing an integrated approach based on satellite images, topographic maps, field measurements, and laboratory analysis. Remote sensing data were spatially analyzed to classify and detect the temporal changes in the surface sediments and geomorphology based on the field measurements (n = 42) as ground truthing points for supervising the classification. Samples from both areas were collected and subjected to grain size (dry mechanical sieving) and X-Ray Diffraction (XRD) analysis. The resulting data were statistically analyzed for grain size distributions and mineralogy based on the US standard set of sieves. The study found that the Aeolian sand sheet deposits are the most frequent recent surface deposits in Kuwait and cover most of the other sediments. The direction of movement of the sand sheets is from NW towards SE. The mineralogical composition of the aeolian recent surface sediments revealed that they are mostly derived from the Dibdibba Formation and Tigris-Euphrates fluvial terrace deposits. Quartz is the most frequent component of the studied surface sediments in the study areas (66%). The calcite mineral is also found in subordinate amounts in the study areas (10%).展开更多
This research study quantifies the PM<sub>10</sub> emission rates (g/s) from cement silos in 25 concrete batching facilities for both controlled and uncontrolled scenarios by applying the USEPA AP-42 guide...This research study quantifies the PM<sub>10</sub> emission rates (g/s) from cement silos in 25 concrete batching facilities for both controlled and uncontrolled scenarios by applying the USEPA AP-42 guidelines step-by-step approach. The study focuses on evaluating the potential environmental impact of cement dust fugitive emissions from 176 cement silos located in 25 concrete batching facilities in the M35 Mussafah industrial area of Abu Dhabi, UAE. Emission factors are crucial for quantifying the PM<sub>10</sub> emission rates (g/s) that support developing source-specific emission estimates for areawide inventories to identify major sources of pollution that provide screening sources for compliance monitoring and air dispersion modeling. This requires data to be collected involves information on production, raw material usage, energy consumption, and process-related details, this was obtained using various methods, including field visits, surveys, and interviews with facility representatives to calculate emission rates accurately. Statistical analysis was conducted on cement consumption and emission rates for controlled and uncontrolled sources of the targeted facilities. The data shows that the average cement consumption among the facilities is approximately 88,160 (MT/yr), with a wide range of variation depending on the facility size and production rate. The emission rates from controlled sources have an average of 4.752E<sup>-04</sup> (g/s), while the rates from uncontrolled sources average 0.6716 (g/s). The analysis shows a significant statistical relationship (p < 0.05) and perfect positive correlation (r = 1) between cement consumption and emission rates, indicating that as cement consumption increases, emission rates tend to increase as well. Furthermore, comparing the emission rates from controlled and uncontrolled scenarios. The data showed a significant difference between the two scenarios, highlighting the effectiveness of control measures in reducing PM<sub>10</sub> emissions. The study’s findings provide insights into the impact of cement silo emissions on air quality and the importance of implementing control measures in concrete batching facilities. The comparative analysis contributes to understanding emission sources and supports the development of pollution control strategies in the Ready-Mix industry.展开更多
Nitrogen(N)supply is the most important factor affecting yield and quality of flue-cured tobacco(FCT).A field experiment and an in situ incubation method were used to study the effects of soil N mineralization in the ...Nitrogen(N)supply is the most important factor affecting yield and quality of flue-cured tobacco(FCT).A field experiment and an in situ incubation method were used to study the effects of soil N mineralization in the later stages of growth on yield and nicotine content of FCT in Fenggang and Jinsha,Guizhou Province.The yield and market value of FCT at Fenggang were much lower than those at Jinsha.However,the nicotine content of middle and upper leaves was much higher at Fenggang than at Jinsha when the same rate of fertilizer N was applied,which might be due to a higher N supply capacity at the Fenggang site.At later stages of growth(7-16 weeks after transplanting),the soil net N mineralization at Fenggang(56 kg N ha^(-1))was almost double that at Jinsha(30 kg N ha^(-1)).While soil NH_4-N and NO_3-N were almost exhausted by the plants or leached 5 weeks after transplanting,the N taken up at the later growth stages at Fenggang were mainly derived from soil N mineralization,which contributed to a high nicotine content in the upper leaves.The order of soil N contribution to N buildup in different leaves was:upper leaves>middle leaves>lower leaves.Thus,soil N mineralization at late growth stages was an important factor affecting N accumulation and therefore the nicotine content in the upper leaves.展开更多
In order to illustrate the change of nitrogen (N) supply capacity after long-term application of manure and chemical fertilizer, as well as to properly manage soil fertility through fertilizer application under the so...In order to illustrate the change of nitrogen (N) supply capacity after long-term application of manure and chemical fertilizer, as well as to properly manage soil fertility through fertilizer application under the soil-climatic conditions of the North China Plain, organic N forms were quantified in the topsoil with different manure and chemical fertilizer treatments in a 15-year fertilizer experiment in a Chinese calcareous alluvial soil. Soil total N (TN) and various organic N forms were significantly influenced by long-term application of chemical fertilizer and manure. TN, total hydrolysable N, acid-insoluble N, amino acid N and ammonium N in the soil increased significantly (P < 0.05) with increasing manure and fertilizer N rates, but were not influenced by increasing P rates. Also, application of manure or N fertilizer or P fertilizer did not significantly influence either the quantity of amino sugar N or its proportion of TN. Application of manure significantly increased (P < 0.05) hydrolysable unknown N, but adding N or P did not. In addition, application of manure or N fertilizer or P fertilizer did not significantly influence the proportions of different soil organic N forms.展开更多
文摘Erosion as a natural process produces soils, which are very important natural resources for the fest land plant- and animal kingdoms. Loss of the soil cover reduces agricultural production, biodiversity, and the role of soil as a filter for infiltrating water to replenish the groundwater. It also threatens the food supplies. The knowledge of erosion rates of rocks and terrains is important for developing proactive measures to protect soils from erosion and loss. In this study, erosion rates of catchment areas were calculated based on dams’ catchment extensions and the sediment loads transported by flood flows into dams’ lakes. The study results show that the chemically, via floodwater, transported quantities of materials are negligible compared to the solid materials transported by the water. It calculates erosion rates ranging from 0.013 to 0.212 mm/yr (13 - 212 m/10<sup>6</sup> yr) for the different catchment areas. Erosion rates in Jordan are, generally, higher than those calculated for the different parts of the world ranging from 2.5 to 60 m/10<sup>6</sup> yr. This fact can be explained by the very steep topography, calcareous rock cover of the catchment areas and the barren rock exposures.
文摘Indeed,polymeric materials have thrived in worldwide sectors over the last five decades due to their versatility and durability,to the point that we can no longer envisage a product that does not contain them.However,many synthetic polymers that have been produced are mostly sourced from petroleum and coal as raw materials,making them environmentally incompatible because they cannot be integrated with what is a natural recycling system.One of the most important aspects of the transition to a circular bioeconomy(CBE)is the provision of more sustainable strategies for resource and waste management.Considering the environmental consequences associated with petroleum-based polymers(PBPs),natural biopolymers,originating from biomass,can be conceived as a promising solution to gradually replace the PBPs,and address,and resolve the potential challenges and prevailing research gaps in the PBPs.The biopolymers have significant advantages over PBPs in terms of low-cost/zero-cost precursors,environmental friendliness,and user-friendliness.The present review dissects the sources,synthesis pathways,structures,characterization,and employment of biopolymers and their composites in water and wastew-ater treatment applications via different scenarios.Furthermore,the CBE model framework proposes potential approaches to applying CBE principles in the wastewater management sector,with a heavy emphasis on not only technology but also organizational and societal reforms.To sum up,the reliance on biopolymers can be considered a crucial tool for assessing the global progress toward CBE,as well as future environmental management and planning.
基金financially supported by the National Natural Science Foundation of China(Nos.32071561 and 31870431)the Science and Technology Innovation Program of Hunan Province(No.2021RC3104)+1 种基金the Research Foundation of the Education Bureau of Hunan Province(No.19B586)the Huitong Forest Ecological Station Funds provided by the State Forestry and Grass Administration of China(No.2021132078)。
文摘Tree species diversity is assumed to be an important component in managing forest ecosystems because of effects on multiple functions or ecosystem multifunctionality.However,the importance of tree diversity in determining multifunctionality in structurally complex subtropical forests relative to other regulators(e.g.,soil microbial diversity,stand structure,and environmental conditions)remains uncertain.In this study,effects of aboveground(species richness and functional and structural diversity)and belowground(bacterial and fungal diversity)biodiversity,functional composition(community-weighted means of species traits),stand structure(diameter at breast height and stand density),and soil factors(pH and bulk density)on multifunctionality(including biomass production,carbon stock,and nutrient cycling)were examined along a tree diversity gradient in subtropical forests.The community-weighted mean of tree maximum height was the best predictor of ecosystem multifunctionality.Functional diversity explained a higher proportion of the variation in multifunctionality than that of species richness and fungal diversity.Stand structure-played an important role in modulating the effects of tree diversity on multifunctionality.The work highlights that species composition and maximizing forest structural complexity are effective strategies to increase forest multifunctionality while also conserving biodiversity in the management of multifunctional forests under global environmental changes.
基金This work was supported by the Science and Technology Innovation Program of Hunan Province(2022RC4027)the Joint Fund for Regional Innovation and Development of the National Natural Science Foundation of China(U22A20570).
文摘The development of allometric biomass models is important process in biomass estimation because the reliability of forest biomass and carbon estimations largely depends on the accuracy and precision of such models.National Forest Inventories(NFI)are detailed assessments of forest resources at national and regional levels that provide valuable data for forest biomass estimation.However,the lack of biomass allometric equations for each tree species in the NFI currently hampers the estimation of national-scale forest biomass.The main objective of this study was to develop allometric biomass regression equations for each tree species in the NFI of China based on limited biomass observations.These equations optimally grouped NFI and biomass observation species according to their phylogenetic relationships.Significant phylogenetic signals demonstrated phylogenetic conservation of the crown-to-stem biomass ratio.Based on phylogenetic relationships,we grouped and matched NFI and biomass observation species into 22 categories.Allometric biomass regression models were developed for each of these 22 species categories,and the models performed successfully(R^(2)=0.97,root mean square error(RMSE)=12.9t·ha^(–1),relative RMSE=11.5%).Furthermore,we found that phylogeny-based models performed more effectively than wood density-based models.The results suggest that grouping species based on their phylogenetic relationships is a reliable approach for the development and selection of accurate allometric equations.
文摘A<sub>2</sub>FeCoO<sub>6-δ</sub> (A = Ca or Sr) is synthesized by the solid-state synthesis method and their specific heat capacities are evaluated at 40˚C using a heat flow meter. The effect of the A-cation size on the specific heat capacity of these compounds is observed. The specific heat capacity of Sr<sub>2</sub>FeCoO<sub>6-δ</sub> is found to be the highest, and that of Ca<sub>2</sub>FeCoO<sub>6-δ</sub> is the lowest while CaSrFeCoO<sub>6-δ</sub> shows the intermediate value. The specific heat capacity decreases with the decrease of the average A-site ionic radius, demonstrating the relationship between heat capacity and A-site ionic radius. The relationship between specific heat capacity and molar mass is also confirmed as the δ value decreases or molar mass increases from Ca<sub>2</sub>FeCoO<sub>6-δ</sub> to CaSrFeCoO<sub>6-δ</sub> to Sr<sub>2</sub>FeCoO<sub>6-δ</sub>.
文摘This research assessed the environmental impact of cement silos emission on the existing concrete batching facilities in M35-Mussafah, Abu Dhabi, United Arab Emirates. These assessments were conducted using an air quality dispersion model (AERMOD) to predict the ambient concentration of Portland Cement particulate matter less than 10 microns (PM<sub>10</sub>) emitted to the atmosphere during loading and unloading activities from 176 silos located in 25 concrete batching facilities. AERMOD was applied to simulate and describe the dispersion of PM<sub>10</sub> released from the cement silos into the air. Simulations were carried out for PM<sub>10</sub> emissions on controlled and uncontrolled cement silos scenarios. Results showed an incremental negative impact on air quality and public health from uncontrolled silos emissions and estimated that the uncontrolled PM<sub>10</sub> emission sources contribute to air pollution by 528958.32 kg/Year. The modeling comparison between the controlled and uncontrolled silos shows that the highest annual average concentration from controlled cement silos is 0.065 μg/m<sup>3</sup>, and the highest daily emission value is 0.6 μg/m<sup>3</sup>;both values are negligible and will not lead to significant air quality impact in the entire study domain. However, the uncontrolled cement silos’ highest annual average concentration value is 328.08 μg/m<sup>3</sup>. The highest daily emission average value was 1250.09 μg/m<sup>3</sup>;this might cause a significant air pollution quality impact and health effects on the public and workers. The short-term and long-term average PM<sub>10</sub> pollutant concentrations at these receptors predicted by the air dispersion model are discussed for both scenarios and compared with local and international air quality standards and guidelines.
文摘Intensive aeolian processes occur due to the scarcity of rainfall and lack of vegetation cover in arid regions. The study of recent surface sediments in arid areas is important for environmental assessments, evaluation of natural resources, and land use planning. In this study, two areas were chosen as they show changes in lithology, environment and landforms. The two study areas are Al-Rawdatain in the northern part, and Al-Managish in the southern part of Kuwait. The current study aims to define the sedimentomorphic zones in these areas, with an emphasis on Quaternary geomorphological evolution by providing an integrated approach based on satellite images, topographic maps, field measurements, and laboratory analysis. Remote sensing data were spatially analyzed to classify and detect the temporal changes in the surface sediments and geomorphology based on the field measurements (n = 42) as ground truthing points for supervising the classification. Samples from both areas were collected and subjected to grain size (dry mechanical sieving) and X-Ray Diffraction (XRD) analysis. The resulting data were statistically analyzed for grain size distributions and mineralogy based on the US standard set of sieves. The study found that the Aeolian sand sheet deposits are the most frequent recent surface deposits in Kuwait and cover most of the other sediments. The direction of movement of the sand sheets is from NW towards SE. The mineralogical composition of the aeolian recent surface sediments revealed that they are mostly derived from the Dibdibba Formation and Tigris-Euphrates fluvial terrace deposits. Quartz is the most frequent component of the studied surface sediments in the study areas (66%). The calcite mineral is also found in subordinate amounts in the study areas (10%).
文摘This research study quantifies the PM<sub>10</sub> emission rates (g/s) from cement silos in 25 concrete batching facilities for both controlled and uncontrolled scenarios by applying the USEPA AP-42 guidelines step-by-step approach. The study focuses on evaluating the potential environmental impact of cement dust fugitive emissions from 176 cement silos located in 25 concrete batching facilities in the M35 Mussafah industrial area of Abu Dhabi, UAE. Emission factors are crucial for quantifying the PM<sub>10</sub> emission rates (g/s) that support developing source-specific emission estimates for areawide inventories to identify major sources of pollution that provide screening sources for compliance monitoring and air dispersion modeling. This requires data to be collected involves information on production, raw material usage, energy consumption, and process-related details, this was obtained using various methods, including field visits, surveys, and interviews with facility representatives to calculate emission rates accurately. Statistical analysis was conducted on cement consumption and emission rates for controlled and uncontrolled sources of the targeted facilities. The data shows that the average cement consumption among the facilities is approximately 88,160 (MT/yr), with a wide range of variation depending on the facility size and production rate. The emission rates from controlled sources have an average of 4.752E<sup>-04</sup> (g/s), while the rates from uncontrolled sources average 0.6716 (g/s). The analysis shows a significant statistical relationship (p < 0.05) and perfect positive correlation (r = 1) between cement consumption and emission rates, indicating that as cement consumption increases, emission rates tend to increase as well. Furthermore, comparing the emission rates from controlled and uncontrolled scenarios. The data showed a significant difference between the two scenarios, highlighting the effectiveness of control measures in reducing PM<sub>10</sub> emissions. The study’s findings provide insights into the impact of cement silo emissions on air quality and the importance of implementing control measures in concrete batching facilities. The comparative analysis contributes to understanding emission sources and supports the development of pollution control strategies in the Ready-Mix industry.
基金Project(41371475)supported by the National Natural Science Foundation of ChinaProject(201509048)supported by the Environmental Protection’s Special Scientific Research for Chinese Public Welfare Industry
基金Project(41371475)supported by the National Natural Science Foundation of ChinaProject(201509048)supported by the Environmental Protection’s Special Scientific Research for Chinese Public Welfare Industry
基金Projects(41877551,41842020)supported by the National Natural Science Foundation of ChinaProject(201509048)supported by the Environmental Protection’s Special Scientific Research for Chinese Public Welfare Industry
基金the Program for Changjiang Scholars and Innovation Research Team in University(No.IRT0511)
文摘Nitrogen(N)supply is the most important factor affecting yield and quality of flue-cured tobacco(FCT).A field experiment and an in situ incubation method were used to study the effects of soil N mineralization in the later stages of growth on yield and nicotine content of FCT in Fenggang and Jinsha,Guizhou Province.The yield and market value of FCT at Fenggang were much lower than those at Jinsha.However,the nicotine content of middle and upper leaves was much higher at Fenggang than at Jinsha when the same rate of fertilizer N was applied,which might be due to a higher N supply capacity at the Fenggang site.At later stages of growth(7-16 weeks after transplanting),the soil net N mineralization at Fenggang(56 kg N ha^(-1))was almost double that at Jinsha(30 kg N ha^(-1)).While soil NH_4-N and NO_3-N were almost exhausted by the plants or leached 5 weeks after transplanting,the N taken up at the later growth stages at Fenggang were mainly derived from soil N mineralization,which contributed to a high nicotine content in the upper leaves.The order of soil N contribution to N buildup in different leaves was:upper leaves>middle leaves>lower leaves.Thus,soil N mineralization at late growth stages was an important factor affecting N accumulation and therefore the nicotine content in the upper leaves.
基金Project supported by the National Natural Science Foundation of China (Nos. 30390080 and 30370287).
文摘In order to illustrate the change of nitrogen (N) supply capacity after long-term application of manure and chemical fertilizer, as well as to properly manage soil fertility through fertilizer application under the soil-climatic conditions of the North China Plain, organic N forms were quantified in the topsoil with different manure and chemical fertilizer treatments in a 15-year fertilizer experiment in a Chinese calcareous alluvial soil. Soil total N (TN) and various organic N forms were significantly influenced by long-term application of chemical fertilizer and manure. TN, total hydrolysable N, acid-insoluble N, amino acid N and ammonium N in the soil increased significantly (P < 0.05) with increasing manure and fertilizer N rates, but were not influenced by increasing P rates. Also, application of manure or N fertilizer or P fertilizer did not significantly influence either the quantity of amino sugar N or its proportion of TN. Application of manure significantly increased (P < 0.05) hydrolysable unknown N, but adding N or P did not. In addition, application of manure or N fertilizer or P fertilizer did not significantly influence the proportions of different soil organic N forms.