This paper summarizes crop straw utilization policies at abroad from the aspects of investment support policies,tax revenue and unsecured loan policies,and reviewed China s crop straw utilization policies from the asp...This paper summarizes crop straw utilization policies at abroad from the aspects of investment support policies,tax revenue and unsecured loan policies,and reviewed China s crop straw utilization policies from the aspects of technical training,project subsidies,straw collection,storage and transportation system construction and socialized service system construction.Combined with the actual situation of Xinjiang,this paper puts forward policy formulation suggestions on crop straw comprehensive utilization.展开更多
This paper introduces in detail the current situation of crop straw resources and comprehensive utilization in Liaoning Province and the basic situation of enterprises using crop straw to produce organic fertilizers.I...This paper introduces in detail the current situation of crop straw resources and comprehensive utilization in Liaoning Province and the basic situation of enterprises using crop straw to produce organic fertilizers.In addition,it analyzes in detail the problems existing in the production of organic fertilizers in Liaoning Province,and finally comes up with some recommendations for using crop straw to produce organic fertilizers.展开更多
A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter (OM) during composting of sewage sludge. The four crop straws included rape straw, wheat ...A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter (OM) during composting of sewage sludge. The four crop straws included rape straw, wheat straw, maize straw and rice straw. The following parameters such as temperature, OM, humic-like substances (HS), fulvic-like acids (FA) and humic-like acids (HA) were determined. The degradation of OM and the formation of HS and HA could be described well by the first-order kinetic model, while the FA content fluctuated during composting. The maximal degradation rates of OM in the compost piles added with rape straw, wheat straw, maize straw and rice straw were 34.7, 46.9, 54.7 and 52.8%, respectively, and the final contents of HS were 118, 128, 141 and 134 g kg-1, respectively, while the humification indices were higher in the compost piles added with maize straw and wheat straw than in those with rice straw and rape straw. The results indicate that a higher hemicellulose content and a lower C/N ratio in crop straw can result in a higher rate of OM degradation and higher contents of HS, while a higher content of lignin can lead to a higher polymerization degree of humic substances in compost piles. The final compost piles added with maize straw has the highest contents of OM, total nitrogen and humus substance as well as the highest values of polymerization degree, while compost piles with rape straw have the highest potassium content and those with rice straw have the highest pH values.展开更多
Utilizing straw as feed and applying cattle and sheep manure fertilizer to the field plays an important role in solving the shortage of feed raw material resources,alleviating the conflict between human beings and liv...Utilizing straw as feed and applying cattle and sheep manure fertilizer to the field plays an important role in solving the shortage of feed raw material resources,alleviating the conflict between human beings and livestock,and realizing the full utilization of straw as a resource and green and low-carbon circular development.We carried out an investigation on the feed utilization of crop straw in Sichuan Province,comprehensively grasped the crop straw resources and its utilization as feed in this province,deeply analyzed the existing problems,and put forward countermeasures and suggestions according to the actual situation in Sichuan,which plays an important role in accelerating the process of straw feed utilization,promoting green development,implementing the rural revitalization strategy,and building a beautiful Sichuan.展开更多
Five crop straws (wheat, rice, maize, oil-rape, and cotton) were first steam-exploded for 2 min at 210℃, 2.5 MPa and then pyrolyzed at 500℃ for 2 h. Steam explosion (SE) induced 47–95% and 5–16% reduction of hemic...Five crop straws (wheat, rice, maize, oil-rape, and cotton) were first steam-exploded for 2 min at 210℃, 2.5 MPa and then pyrolyzed at 500℃ for 2 h. Steam explosion (SE) induced 47–95% and 5–16% reduction of hemicellulose and cellulose, respectively, in the crop straws. The biochars derived from SE-treated feedstocks had a lower specific surface area (SSA) and pore volume, compared to those from pristine feedstocks, with one exception that SE enhanced SSA of oil-rape straw biochar by approximately 16 times. After SE, biochars had significant higher anion exchange capacity (AEC) (6.88–11.44 cmol kg–1) and point of zero net charges (PZNC) (pH 3.61–5.32) values. It can thus be speculated that these biochars may have higher potential for anions adsorption. In addition, oil-rape straw might be suitable to SE pretreatment for preparing biochar as a soil amendment and sorbent as well. Further work is required for testing its application in soil.展开更多
Spring maize is one of the most popular crops planted in northeastem China. The cropping systems involving spring maize have been maintaining high production through intensive management practices. However, the high r...Spring maize is one of the most popular crops planted in northeastem China. The cropping systems involving spring maize have been maintaining high production through intensive management practices. However, the high rates of nitrogen (N) fertilizers application could have introduced a great amount of nitrous oxide (N2O) into the atmosphere. It is crucial for sustaining the maize production systems to reduce N2O emissions meanwhile maintaining the optimum yields by adopting alternative farming management practices. The goal of this study was to evaluate effects of alternative fertilization and crop residue management practices on N2O emission as well as crop yield for a typical maize field in northeastern China. Field experiments were conducted during the 2010-2011 maize growing seasons (from early May to late September) in Liaoning Province, northeastern China. N2O fluxes were measured at the field plots with six different treatments including no N fertilizer use (CK), farmers' conventional N fertilizer application rate (FP), reduced N fertilizer rate (OPT), reduced N fertilizer rate combined with crop straw amendment (OPTS), slow-release N fertilizer (CRF), and reduced N fertilizer rate combined with nitrification inhibitor (OPT+DCD). The static chamber method combined with gas chromatography technique was employed to conduct the measurements of N2O fluxes. The field data showed that N2O emissions varied across the treatments. During the maize growing season in 2010, the total N2O emissions under the treatments of CK, FP, OPT, OPTS, and CRF were 0.63, 1.11, 1.03, 1.26, and 0.98 kg N ha-1, respectively. The seasonal cumulative N2O emissions were 0.54, 1.07, 0.96, 1.12, and 0.84 kg N ha1, respectively, under CK, FP, OPT, OPTS, and OPT+DCD in 2011. In comparison with FP, CRF or OPT+DCD reduced the N2O emissions by 12 or 21%, respectively, while the crop yields remained unchanged. The results indicate that the reduction of N-fertilizer application rate in combination with the slow-release fertilizer type or nitrification inhibitor could effectively mitigate N2O emissions from the tested field. The incorporation of crop residue didn't show positive effect on mitigating N2O emissions from the tested cropping system. The field study can provide useful information for the on-going debate on alternative N fertilization strategies and crop straw management in China. However, further studies would be needed to explore the long-term impacts of the alternative management practices on a wide range of environmental services.展开更多
Cr(Ⅲ) adsorption by biochars generated from peanut, soybean, canola and rice straws is investigated with batch methods. Adsorption of Cr(Ⅲ) increased as pH rose from 2.5 to 5.0. Adsorption of Cr(Ⅲ) led to pea...Cr(Ⅲ) adsorption by biochars generated from peanut, soybean, canola and rice straws is investigated with batch methods. Adsorption of Cr(Ⅲ) increased as pH rose from 2.5 to 5.0. Adsorption of Cr(Ⅲ) led to peak position shifts in the FFIR-PAS spectra of the biochars and made zeta potential values less negative, suggesting the formation of surface complexes between Cr^3+ and functional groups on the biochars. The adsorption capacity of Cr(Ⅲ) followed the order: peanut straw char 〉 soybean straw char 〉 canola straw char 〉 rice straw char, which was consistent with the content of acidic functional groups on the biochars. The increase in Cr^3+ hydrolysis as the pH rose was one of the main reasons for the increased adsorption of Cr(Ⅲ) by the biochars at higher pH values. Cr(llI) can be adsorbed by the biochars through electrostatic attraction between negative surfaces and Cr^3+, but the relative contribution of electrostatic adsorption was less than 5%. Therefore, Cr(Ⅲ) was mainly adsorbed by the biochars through specific adsorption. The Langumir and Freundlich equations fitted the adsorption isotherms well and can therefore be used to describe the adsorption behavior of Cr(Ⅲ) by the crop straw biochars. The crop straw biochars have great adsorption capacities for Cr(Ⅲ) under acidic conditions and can be used as adsorbents to remove Cr(Ⅲ) from acidic wastewaters.展开更多
Fresh straw burning (SB) particles were generated in the laboratory by the combustion of rice straw and corn straw. The chemical composition and mixing state of the fresh SB particles were investigated by an Aerosol...Fresh straw burning (SB) particles were generated in the laboratory by the combustion of rice straw and corn straw. The chemical composition and mixing state of the fresh SB particles were investigated by an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS). Based on the mass spectral patterns, the SB particles were clustered into four major types: Salt, Organic Carbon (OC), Elemental Carbon (EC), and internally mixed particles of EC and OC (EC-OC). In addition, particles containing ash, polycyclic aromatic hydrocarbons, heavy metals or nicotine were also observed. Physical and chemical changes of the SB particles immediately after the emission were analyzed with highly time-resolved data. During the aging processes, the average particle size increased steadily. Freshly emitted organic compounds were gradu- ally oxidized to more oxygenated compounds in the OC- containing particles. Meanwhile, an important displace- ment reaction (2KCI+ SO24- KzSO4 + 2C1-) was observed. The marker ions for SB particles were optimized and applied to identify the SB particles in the ambient atmosphere. The fluctuation of the number fraction of ambient SB particles sorted by ATOFMS agrees well with that of water soluble K+ measured by an online ion chromatography, demonstrating that the optimized marker ions could be good tracers for SB particles in field measurements.展开更多
This study evaluated eight different types of heat supply modes based on crop residues utilization in the rural area of Northern China,including straw densified solid fuel combustion,pyrolysis char combustion,biogas c...This study evaluated eight different types of heat supply modes based on crop residues utilization in the rural area of Northern China,including straw densified solid fuel combustion,pyrolysis char combustion,biogas combustion,and pyrolysis gas combustion for single household heating;straw densified solid fuel combustion,baling straw combustion,biogas combustion,and pyrolysis gas combustion for centralized heating;centralized gas supply and centralized pyrolysis gas supply modes.Comprehensively evaluation was the cost of these different eight heat supply modes.The results showed that the cost of straw densified solid fuel combustion,pyrolysis char combustion for single household heating were 2346 RMB/household and 2390 RMB/household.With the heating scale of 200-500 households,the pipe network distance was 8 m/household,and the total annual heating cost was predicted at 2201-2992 RMB/household.Among them,the cost of straw baling combustion for centralized heating was the lowest,the cost of densified solid fuel,biogas,and pyrolysis for centralized heating was the second,and the cost of biogas and pyrolysis gas for centralized gas supply was the highest.For the increase in every 1 m of the pipeline distance,the investment cost will increase by about 645 RMB for each household.This study provides a basis for the implementation of clean heat supply technologies in less-developed areas and guidance of village heat-supply subsidy policies.展开更多
Emissions resulting from crop straw field burning in China, which have caused serious environmental problems in China, are estimated in this paper. From the county-level data of crop production in 2000― 2003 from the...Emissions resulting from crop straw field burning in China, which have caused serious environmental problems in China, are estimated in this paper. From the county-level data of crop production in 2000― 2003 from the government statistics, taking into account the ratio of residue and grain, the total amount of crop straw production is estimated to be about 600 Tg per year, 76% of which are rice, wheat and corn straw. With reference to the data of living standards, the percentage of crop straw burnt in fields for counties are obtained and consequently the total amount of burnt straws is approximately 140 Tg/year. With the emission factors from literature and experiments, appropriate emission factors have been obtained. The total amounts of PM, SO_2, NO_x, NH_3, CH_4, BC, OC, VOC, CO, CO_2 emissions from field burning of crop straw in China are estimated. All emissions are presented at county level. Some pollutants, such as BC, VOC, OC, CO and CO_2, are contributing a major portion to the total emissions of China. This paper uses a map with resolution of 0.2°×0.2° to present the PM emissions distribution from crop straw burnt in 2003. The results show a significant regional unevenness of emissions, with larger amounts of pollutions coming from the provinces in eastern and northeast China. The regions with higher emissions per unit area are located as a belt stretching from northeast China to eastern China.展开更多
Two variable charge soils were incubated with biochars derived from straws of peanut, soybean, canola, and rice to investigate the effect of the biochars on their chemical properties and Pb(II) adsorption using batc...Two variable charge soils were incubated with biochars derived from straws of peanut, soybean, canola, and rice to investigate the effect of the biochars on their chemical properties and Pb(II) adsorption using batch experiments. The results showed soil cation exchange capacity (CEC) and pH significantly increased after 30 d of incubation with the biochars added. The incorporation of the biochars markedly increased the adsorption of Pb(II), and both the electrostatic and non-electrostatic adsorption mechanisms contributed to Pb(II) adsorption by the variable charge soils. Adsorption isotherms illustrated legume- straw derived biochars more greatly increased Pb(II) adsorption on soils through the non-electrostatic mechanism via the formation of surface complexes between Pb(II) and acid functional groups of the biochars than did non-legume straw biochars. The adsorption capacity of Pb(II) increased, while the desorption amount slightly decreased with the increasing suspension pH for the studied soils, especially in a high suspension pH, indicating that precipitation also plays an important role in immobilizing Pb(II) to the soils.展开更多
Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The experiments on long-term application of K fertiliz...Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The experiments on long-term application of K fertilizer and wheat straw to soil in Hebei fluvo aquic soil and Shanxi brown soil in northern China were begun in 1992. The results showed that K fertilizer and straw could improve the yields of wheat and maize with the order of NPK + St 〉 NPK 〉 NP + St 〉 NP, and treatment of K fertilizer made a significant difference to NP, and the efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei. In contrast with Shanxi, the wastage of soil potassium was a more serious issue in the rotation system in Hebei, only treatment of NPK + St showed a surplus of potassium and the others showed a wane. K fertilizer and straw could improve the content of water-soluble K, nonspecifically adsorbed K, non-exchangeable K, mineral K, and total K in contrast to NP; however, K fertilizer and straw reduce the proportion of mineral K and improve proportion of other forms of potassium in the two locating sites. Compared with the beginning of orientation, temporal variability character of soil K content and proportion showed a difference between the two soil types; furthermore, there was a decrease in the content of mineral K and total K simultaneously in the two locating sites. As a whole, the effect of K fertilizer applied to soil directly excelled to wheat straw to soil. Wheat straw to soil was an effective measure to complement potassium to increase crop yield and retard the decrease of soil K.展开更多
研究多元化种植模式下,不同前茬秸秆还田与水氮管理对水稻产量形成、干物质积累分配及氮素吸收利用的影响。2018—2019年以杂交稻F优498为材料,采用三因素裂裂区设计,主区设置油菜-水稻(Py)、小麦-水稻(Px)、青菜-水稻(Pq)3种种植模式...研究多元化种植模式下,不同前茬秸秆还田与水氮管理对水稻产量形成、干物质积累分配及氮素吸收利用的影响。2018—2019年以杂交稻F优498为材料,采用三因素裂裂区设计,主区设置油菜-水稻(Py)、小麦-水稻(Px)、青菜-水稻(Pq)3种种植模式秸秆还田,裂区设置常规淹水灌溉(W_(0))和干湿交替灌溉(W_(1))2种水分管理方式,裂裂区设置不施氮处理(N_(0))、常规施氮处理(N_(1))、精量减氮处理(N_(2))3个施氮水平,分析测定了拔节期、齐穗期和成熟期不同处理下秸秆还田的腐解率、氮素释放率、水稻各器官的干物质积累分配、植株氮素吸收利用以及籽粒产量。结果表明,Py的平均产量分别较Px、Pq增加2.55%、13.99%,主要原因是其有效穗数和千粒重较高;Py可促进各营养器官干物质和氮素积累,有利于干物质分配、提高茎鞘氮素贡献率和氮肥利用率,Py各时期的平均干物质积累总量、氮素积累总量分别比Px和Pq增加5.25%、7.48%和14.60%、17.30%,Py的氮肥偏生产力较Pq显著增加24.90%,但Py的秸秆腐解率和氮素释放率较低。3种模式下W1处理的水稻产量分别比W0处理增加5.10%(Py)、1.76%(Px)和4.80%(Pq),W1处理可促进秸秆腐解和氮素释放,促进干物质积累和氮素吸收转运,有利于Py和Px模式下的干物质分配,进而提高氮肥利用率。同一秸秆还田和水分管理下,N2处理可促进秸秆腐解和氮素释放,有利于干物质分配和氮素转运,提高了齐穗期、成熟期茎鞘和叶片氮素积累量,进而提高氮肥利用率,N2处理的产量、干物质积累量较N1处理略有下降,但二者差异不显著。综合考虑分析,油-稻种植模式下,油菜秸秆还田配合干湿交替灌溉与精量减氮(120 kg hm^(-2))有利于干物质积累分配、氮素吸收转运,进而提高氮肥农学利用率、氮肥偏生产力,并可节约20%氮肥投入,实现水稻稳产高效生产。展开更多
基金Supported by Natural Science Foundation of Xinjiang Autonomous Region(2021D01F06).
文摘This paper summarizes crop straw utilization policies at abroad from the aspects of investment support policies,tax revenue and unsecured loan policies,and reviewed China s crop straw utilization policies from the aspects of technical training,project subsidies,straw collection,storage and transportation system construction and socialized service system construction.Combined with the actual situation of Xinjiang,this paper puts forward policy formulation suggestions on crop straw comprehensive utilization.
文摘This paper introduces in detail the current situation of crop straw resources and comprehensive utilization in Liaoning Province and the basic situation of enterprises using crop straw to produce organic fertilizers.In addition,it analyzes in detail the problems existing in the production of organic fertilizers in Liaoning Province,and finally comes up with some recommendations for using crop straw to produce organic fertilizers.
基金funded by the the Key Technologied R&D Program of China during the 12th Five-Year Plan period (2013BAJ11B03)the Science & Technology Commission of Chongqing, China (CSTC, 2008AC7013)
文摘A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter (OM) during composting of sewage sludge. The four crop straws included rape straw, wheat straw, maize straw and rice straw. The following parameters such as temperature, OM, humic-like substances (HS), fulvic-like acids (FA) and humic-like acids (HA) were determined. The degradation of OM and the formation of HS and HA could be described well by the first-order kinetic model, while the FA content fluctuated during composting. The maximal degradation rates of OM in the compost piles added with rape straw, wheat straw, maize straw and rice straw were 34.7, 46.9, 54.7 and 52.8%, respectively, and the final contents of HS were 118, 128, 141 and 134 g kg-1, respectively, while the humification indices were higher in the compost piles added with maize straw and wheat straw than in those with rice straw and rape straw. The results indicate that a higher hemicellulose content and a lower C/N ratio in crop straw can result in a higher rate of OM degradation and higher contents of HS, while a higher content of lignin can lead to a higher polymerization degree of humic substances in compost piles. The final compost piles added with maize straw has the highest contents of OM, total nitrogen and humus substance as well as the highest values of polymerization degree, while compost piles with rape straw have the highest potassium content and those with rice straw have the highest pH values.
基金Mutton Sheep High-Quality and High-Yield Forage Variety Selection and Production Application Post of Sichuan Mutton Sheep Innovation Team(sccxtd-2020-14).
文摘Utilizing straw as feed and applying cattle and sheep manure fertilizer to the field plays an important role in solving the shortage of feed raw material resources,alleviating the conflict between human beings and livestock,and realizing the full utilization of straw as a resource and green and low-carbon circular development.We carried out an investigation on the feed utilization of crop straw in Sichuan Province,comprehensively grasped the crop straw resources and its utilization as feed in this province,deeply analyzed the existing problems,and put forward countermeasures and suggestions according to the actual situation in Sichuan,which plays an important role in accelerating the process of straw feed utilization,promoting green development,implementing the rural revitalization strategy,and building a beautiful Sichuan.
基金funded by the National Key Technology R&D Program of China(2015BAD05B03)
文摘Five crop straws (wheat, rice, maize, oil-rape, and cotton) were first steam-exploded for 2 min at 210℃, 2.5 MPa and then pyrolyzed at 500℃ for 2 h. Steam explosion (SE) induced 47–95% and 5–16% reduction of hemicellulose and cellulose, respectively, in the crop straws. The biochars derived from SE-treated feedstocks had a lower specific surface area (SSA) and pore volume, compared to those from pristine feedstocks, with one exception that SE enhanced SSA of oil-rape straw biochar by approximately 16 times. After SE, biochars had significant higher anion exchange capacity (AEC) (6.88–11.44 cmol kg–1) and point of zero net charges (PZNC) (pH 3.61–5.32) values. It can thus be speculated that these biochars may have higher potential for anions adsorption. In addition, oil-rape straw might be suitable to SE pretreatment for preparing biochar as a soil amendment and sorbent as well. Further work is required for testing its application in soil.
基金This work was supported by the National Major Science and Technology Program for Water Pollution Control and Treatment[grant number 2017ZX07101001]the National Natural Science Foundation of China[grant numbers 41573079 and 41675144]the Chinese Academy of Sciences Pioneer Hundred Talents Program.
基金the National Natural Science Foundation of China(31270486)the Special Fund for Agriculture Scientific Non-Profit Research of China(201103039)+1 种基金the National Basic Research Program of China(2012CB417104)the National Nonprofit Institute Research Grant of Chinese Academy of Agricultural Sciences(IARRP-2014-402-15)
文摘Spring maize is one of the most popular crops planted in northeastem China. The cropping systems involving spring maize have been maintaining high production through intensive management practices. However, the high rates of nitrogen (N) fertilizers application could have introduced a great amount of nitrous oxide (N2O) into the atmosphere. It is crucial for sustaining the maize production systems to reduce N2O emissions meanwhile maintaining the optimum yields by adopting alternative farming management practices. The goal of this study was to evaluate effects of alternative fertilization and crop residue management practices on N2O emission as well as crop yield for a typical maize field in northeastern China. Field experiments were conducted during the 2010-2011 maize growing seasons (from early May to late September) in Liaoning Province, northeastern China. N2O fluxes were measured at the field plots with six different treatments including no N fertilizer use (CK), farmers' conventional N fertilizer application rate (FP), reduced N fertilizer rate (OPT), reduced N fertilizer rate combined with crop straw amendment (OPTS), slow-release N fertilizer (CRF), and reduced N fertilizer rate combined with nitrification inhibitor (OPT+DCD). The static chamber method combined with gas chromatography technique was employed to conduct the measurements of N2O fluxes. The field data showed that N2O emissions varied across the treatments. During the maize growing season in 2010, the total N2O emissions under the treatments of CK, FP, OPT, OPTS, and CRF were 0.63, 1.11, 1.03, 1.26, and 0.98 kg N ha-1, respectively. The seasonal cumulative N2O emissions were 0.54, 1.07, 0.96, 1.12, and 0.84 kg N ha1, respectively, under CK, FP, OPT, OPTS, and OPT+DCD in 2011. In comparison with FP, CRF or OPT+DCD reduced the N2O emissions by 12 or 21%, respectively, while the crop yields remained unchanged. The results indicate that the reduction of N-fertilizer application rate in combination with the slow-release fertilizer type or nitrification inhibitor could effectively mitigate N2O emissions from the tested field. The incorporation of crop residue didn't show positive effect on mitigating N2O emissions from the tested cropping system. The field study can provide useful information for the on-going debate on alternative N fertilization strategies and crop straw management in China. However, further studies would be needed to explore the long-term impacts of the alternative management practices on a wide range of environmental services.
基金supported by the National Natural Science Foundation of China(No.41230855)the National Key Technology R&D Program of China(No.2012BAJ24B06)
文摘Cr(Ⅲ) adsorption by biochars generated from peanut, soybean, canola and rice straws is investigated with batch methods. Adsorption of Cr(Ⅲ) increased as pH rose from 2.5 to 5.0. Adsorption of Cr(Ⅲ) led to peak position shifts in the FFIR-PAS spectra of the biochars and made zeta potential values less negative, suggesting the formation of surface complexes between Cr^3+ and functional groups on the biochars. The adsorption capacity of Cr(Ⅲ) followed the order: peanut straw char 〉 soybean straw char 〉 canola straw char 〉 rice straw char, which was consistent with the content of acidic functional groups on the biochars. The increase in Cr^3+ hydrolysis as the pH rose was one of the main reasons for the increased adsorption of Cr(Ⅲ) by the biochars at higher pH values. Cr(llI) can be adsorbed by the biochars through electrostatic attraction between negative surfaces and Cr^3+, but the relative contribution of electrostatic adsorption was less than 5%. Therefore, Cr(Ⅲ) was mainly adsorbed by the biochars through specific adsorption. The Langumir and Freundlich equations fitted the adsorption isotherms well and can therefore be used to describe the adsorption behavior of Cr(Ⅲ) by the crop straw biochars. The crop straw biochars have great adsorption capacities for Cr(Ⅲ) under acidic conditions and can be used as adsorbents to remove Cr(Ⅲ) from acidic wastewaters.
基金This work was supported by The National Natural Science Foundation of China (Grant Nos. 21177027 and 41275126), Ministry of Science and Technology of China (2012YQ220113-4), the Science & Technology Commission of Shanghai Municipality (12DJ1400100, 14XD 1400600), and the Jiangsu Provincial Collaborative Innovation Center of Climate Change.
文摘Fresh straw burning (SB) particles were generated in the laboratory by the combustion of rice straw and corn straw. The chemical composition and mixing state of the fresh SB particles were investigated by an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS). Based on the mass spectral patterns, the SB particles were clustered into four major types: Salt, Organic Carbon (OC), Elemental Carbon (EC), and internally mixed particles of EC and OC (EC-OC). In addition, particles containing ash, polycyclic aromatic hydrocarbons, heavy metals or nicotine were also observed. Physical and chemical changes of the SB particles immediately after the emission were analyzed with highly time-resolved data. During the aging processes, the average particle size increased steadily. Freshly emitted organic compounds were gradu- ally oxidized to more oxygenated compounds in the OC- containing particles. Meanwhile, an important displace- ment reaction (2KCI+ SO24- KzSO4 + 2C1-) was observed. The marker ions for SB particles were optimized and applied to identify the SB particles in the ambient atmosphere. The fluctuation of the number fraction of ambient SB particles sorted by ATOFMS agrees well with that of water soluble K+ measured by an online ion chromatography, demonstrating that the optimized marker ions could be good tracers for SB particles in field measurements.
基金The authors acknowledge that this work was financially supported by the Agricultural Science and Technology Innovation Program(CAAS-ASTIP),China Agriculture Research System(CARS-02),which enables us to complete field surveys and data analysis.
文摘This study evaluated eight different types of heat supply modes based on crop residues utilization in the rural area of Northern China,including straw densified solid fuel combustion,pyrolysis char combustion,biogas combustion,and pyrolysis gas combustion for single household heating;straw densified solid fuel combustion,baling straw combustion,biogas combustion,and pyrolysis gas combustion for centralized heating;centralized gas supply and centralized pyrolysis gas supply modes.Comprehensively evaluation was the cost of these different eight heat supply modes.The results showed that the cost of straw densified solid fuel combustion,pyrolysis char combustion for single household heating were 2346 RMB/household and 2390 RMB/household.With the heating scale of 200-500 households,the pipe network distance was 8 m/household,and the total annual heating cost was predicted at 2201-2992 RMB/household.Among them,the cost of straw baling combustion for centralized heating was the lowest,the cost of densified solid fuel,biogas,and pyrolysis for centralized heating was the second,and the cost of biogas and pyrolysis gas for centralized gas supply was the highest.For the increase in every 1 m of the pipeline distance,the investment cost will increase by about 645 RMB for each household.This study provides a basis for the implementation of clean heat supply technologies in less-developed areas and guidance of village heat-supply subsidy policies.
基金Supported by the National Key Basic Research Project of China (Grant No. 2006CB403700)
文摘Emissions resulting from crop straw field burning in China, which have caused serious environmental problems in China, are estimated in this paper. From the county-level data of crop production in 2000― 2003 from the government statistics, taking into account the ratio of residue and grain, the total amount of crop straw production is estimated to be about 600 Tg per year, 76% of which are rice, wheat and corn straw. With reference to the data of living standards, the percentage of crop straw burnt in fields for counties are obtained and consequently the total amount of burnt straws is approximately 140 Tg/year. With the emission factors from literature and experiments, appropriate emission factors have been obtained. The total amounts of PM, SO_2, NO_x, NH_3, CH_4, BC, OC, VOC, CO, CO_2 emissions from field burning of crop straw in China are estimated. All emissions are presented at county level. Some pollutants, such as BC, VOC, OC, CO and CO_2, are contributing a major portion to the total emissions of China. This paper uses a map with resolution of 0.2°×0.2° to present the PM emissions distribution from crop straw burnt in 2003. The results show a significant regional unevenness of emissions, with larger amounts of pollutions coming from the provinces in eastern and northeast China. The regions with higher emissions per unit area are located as a belt stretching from northeast China to eastern China.
基金supported by the Key Technoligies R&D Program of China during the 12th Five-Year Plan period (2012BAJ24B06)the National Natural Science Foundation of China (41230855)
文摘Two variable charge soils were incubated with biochars derived from straws of peanut, soybean, canola, and rice to investigate the effect of the biochars on their chemical properties and Pb(II) adsorption using batch experiments. The results showed soil cation exchange capacity (CEC) and pH significantly increased after 30 d of incubation with the biochars added. The incorporation of the biochars markedly increased the adsorption of Pb(II), and both the electrostatic and non-electrostatic adsorption mechanisms contributed to Pb(II) adsorption by the variable charge soils. Adsorption isotherms illustrated legume- straw derived biochars more greatly increased Pb(II) adsorption on soils through the non-electrostatic mechanism via the formation of surface complexes between Pb(II) and acid functional groups of the biochars than did non-legume straw biochars. The adsorption capacity of Pb(II) increased, while the desorption amount slightly decreased with the increasing suspension pH for the studied soils, especially in a high suspension pH, indicating that precipitation also plays an important role in immobilizing Pb(II) to the soils.
文摘Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The experiments on long-term application of K fertilizer and wheat straw to soil in Hebei fluvo aquic soil and Shanxi brown soil in northern China were begun in 1992. The results showed that K fertilizer and straw could improve the yields of wheat and maize with the order of NPK + St 〉 NPK 〉 NP + St 〉 NP, and treatment of K fertilizer made a significant difference to NP, and the efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei. In contrast with Shanxi, the wastage of soil potassium was a more serious issue in the rotation system in Hebei, only treatment of NPK + St showed a surplus of potassium and the others showed a wane. K fertilizer and straw could improve the content of water-soluble K, nonspecifically adsorbed K, non-exchangeable K, mineral K, and total K in contrast to NP; however, K fertilizer and straw reduce the proportion of mineral K and improve proportion of other forms of potassium in the two locating sites. Compared with the beginning of orientation, temporal variability character of soil K content and proportion showed a difference between the two soil types; furthermore, there was a decrease in the content of mineral K and total K simultaneously in the two locating sites. As a whole, the effect of K fertilizer applied to soil directly excelled to wheat straw to soil. Wheat straw to soil was an effective measure to complement potassium to increase crop yield and retard the decrease of soil K.
文摘研究多元化种植模式下,不同前茬秸秆还田与水氮管理对水稻产量形成、干物质积累分配及氮素吸收利用的影响。2018—2019年以杂交稻F优498为材料,采用三因素裂裂区设计,主区设置油菜-水稻(Py)、小麦-水稻(Px)、青菜-水稻(Pq)3种种植模式秸秆还田,裂区设置常规淹水灌溉(W_(0))和干湿交替灌溉(W_(1))2种水分管理方式,裂裂区设置不施氮处理(N_(0))、常规施氮处理(N_(1))、精量减氮处理(N_(2))3个施氮水平,分析测定了拔节期、齐穗期和成熟期不同处理下秸秆还田的腐解率、氮素释放率、水稻各器官的干物质积累分配、植株氮素吸收利用以及籽粒产量。结果表明,Py的平均产量分别较Px、Pq增加2.55%、13.99%,主要原因是其有效穗数和千粒重较高;Py可促进各营养器官干物质和氮素积累,有利于干物质分配、提高茎鞘氮素贡献率和氮肥利用率,Py各时期的平均干物质积累总量、氮素积累总量分别比Px和Pq增加5.25%、7.48%和14.60%、17.30%,Py的氮肥偏生产力较Pq显著增加24.90%,但Py的秸秆腐解率和氮素释放率较低。3种模式下W1处理的水稻产量分别比W0处理增加5.10%(Py)、1.76%(Px)和4.80%(Pq),W1处理可促进秸秆腐解和氮素释放,促进干物质积累和氮素吸收转运,有利于Py和Px模式下的干物质分配,进而提高氮肥利用率。同一秸秆还田和水分管理下,N2处理可促进秸秆腐解和氮素释放,有利于干物质分配和氮素转运,提高了齐穗期、成熟期茎鞘和叶片氮素积累量,进而提高氮肥利用率,N2处理的产量、干物质积累量较N1处理略有下降,但二者差异不显著。综合考虑分析,油-稻种植模式下,油菜秸秆还田配合干湿交替灌溉与精量减氮(120 kg hm^(-2))有利于干物质积累分配、氮素吸收转运,进而提高氮肥农学利用率、氮肥偏生产力,并可节约20%氮肥投入,实现水稻稳产高效生产。