Passive-warming, open-top chambers(OTCs) are widely applied for studying the effects of future climate warming on coastal wetlands. In this study, a set of six OTCs were established at a Phragmites wetland located in ...Passive-warming, open-top chambers(OTCs) are widely applied for studying the effects of future climate warming on coastal wetlands. In this study, a set of six OTCs were established at a Phragmites wetland located in the Yellow River Delta of Dongying City, China. With data collected through online transmission and in-situ sensors, the attributes and patterns of realized OTCs warming are demonstrated.The authors also quantified the preliminary influence of experimental chamber warming on plant traits.OTCs produced an elevated average air temperature of 0.8°C(relative to controls) during the growing season(June to October) of 2018, and soil temperatures actually decreased by 0.54°C at a depth of 5 cm and 0.46°C at a depth of 30 cm in the OTCs. Variations in diel patterns of warming depend greatly on the heat sources of incoming radiation in the daytime versus soil heat flux at night. Warming effects were often larger during instantaneous analyses and influenced OTCs air temperatures from-2.5°C to 8.3°C dependent on various meteorological conditions at any given time, ranging from cooling influences from vertical heat exchange and vegetation to radiation-associated warming. Night-time temperature depressions in the OTCs were due to the low turbulence inside OTCs and changes in surface soilatmosphere heat transfer. Plant shoot density, basal diameter, and biomass of Phragmites decreased by23.2%, 6.3%, and 34.0%, respectively, under experimental warming versus controls, and plant height increased by 4.3%, reflecting less carbon allocation to stem structures as plants in the OTCs experienced simultaneous wind buffering. While these passive-warming OTCs created the desired warming effects both to the atmosphere and soils, pest damages on the plant leaves and lodging within the OTCs were extensive and serious, creating the need to consider control options for these chambers and the replicated OTCs studies underway in other Chinese Phragmites marshes(Panjin and Yancheng).展开更多
Empty steel-tanks are very much susceptible against buckling induced by wind loading.Ring and vertical stiffeners are commonly used to provide necessary strength to thin-walled steel tanks to resist wind-induced buckl...Empty steel-tanks are very much susceptible against buckling induced by wind loading.Ring and vertical stiffeners are commonly used to provide necessary strength to thin-walled steel tanks to resist wind-induced buckling.The authors have studied the performance of a unique,ribonucleic acid structure-inspired,stiffening-helix mechanism against the wind-induced buckling of open-top,cylindrical,empty,steel-tank.The most important output parameter of this study is the load multiplier(λ)of buckling,as it defines the stability of tank-shell against wind-induced buckling.The study variables are tank-height to tank-diameter(H/D)ratio,tank-radius to wall-thickness(rlt)ratio,basic wind speed(V)and helix pitch length to tank-height(L_(p)/H)ratio.This study has been performed through multiphysics system-coupling of computational fluid dynamics and structural mechanics(eigenvalue buckling).The stiffening-helix can provide necessary strength to open-top,cylindrical,steel-tank economically against wind-induced buckling.An artificial neural network(ANN)has been trained with the analytical data to develop a predictive model.The proposed predictive ANN model produces 99.11% average accuracy.展开更多
Gaseous nitrous acid(HONO)is a critical contributor to daytime hydroxyl radical in the troposphere.Livestock farming has been recognized as an overlooked HONO source,but the lack of detailed flux measurements from liv...Gaseous nitrous acid(HONO)is a critical contributor to daytime hydroxyl radical in the troposphere.Livestock farming has been recognized as an overlooked HONO source,but the lack of detailed flux measurements from livestock and poultry wastes would cause uncertainties in modeling its environmental impacts.Here,based on field flux measurements and laboratory experiments,we observed substantial HONO emissions from the composting of swine feces and chicken manure in the warm season,which might be mainly attributed to nitrification process in livestock and poultry wastes.The HONO emission from chicken manure was found to bemuch higher than that from swine feces,and the higher NH3 emission but lower N2O and NO emissions fromchicken manurewere also observed.Considering that the interaction among these nitrogen species during nitrification process,the obviously lower HONO emission from swine feces was likely to be explained by the lack of the total ammonia nitrogen and H+donors in swine feces.Temperature is also a key factor that influences the HONO emission from livestock wastes.In addition,the total HONO emission from swine feces in Chinawas estimated to be approximately 107.7 Gg-N/yr according to the national swine amounts,which is comparable to the national soil HONO emissions,underscoring its non-negligible contribution to regional air quality.Therefore,effective emission control of HONO fromlivestock and poultry wastes should be carried out to further improve air quality in China.展开更多
在气候变化背景下,探究关中台塬区冬小麦生长发育过程中主要农艺性状及干物质分配对增温的响应特征,对评估冬小麦的敏感性及适应性具有重要意义。本文以冬小麦品种郑麦1860号为研究对象,通过开顶式气室(Open Top Chamber,OTC)模拟增温环...在气候变化背景下,探究关中台塬区冬小麦生长发育过程中主要农艺性状及干物质分配对增温的响应特征,对评估冬小麦的敏感性及适应性具有重要意义。本文以冬小麦品种郑麦1860号为研究对象,通过开顶式气室(Open Top Chamber,OTC)模拟增温环境,分析增温对冬小麦生长发育过程的影响。结果表明,在小麦生育期内,气室内外温度存在显著差异(p<0.05),OTC内部平均温度较外部高0.8℃;增温条件下,小麦各物候期平均提前6 d,且株高明显增加。返青—抽穗阶段,OTC对小麦叶面积有促进作用,而扬花—乳熟阶段,则对叶面积有抑制作用。增温促进根系生长,使单株根系长度增加37.48%,细根表面积增加35.28%,但对根系生物量有抑制作用,OTC处理组较对照组减少7.60%;增温对茎、叶和穗的干物质量均有促进作用,但乳熟期叶干物质量例外。OTC增温对冬小麦营养生长期的功能性状具有明显促进作用,但对生殖生长期的功能性状影响不显著,甚至表现出一定的抑制作用。展开更多
基金jointly funded by the Marine S&T Fund of Shandong Province for the Pilot National Laboratory for Marine Science and Technology (Qingdao)(2022QNLM 040003-3)the National Key R&D Program of China (2016YFE0109600)+3 种基金National Natural Science Foundation of China (U22A20558, 41240022, 41876057, 40872167, 41602143)China Geological Survey (1212010611402, GZH201200503, and DD20160144)by in-kind support from the Land Carbon ProgramLand Change Science R&D Program of the United States Geological Survey。
文摘Passive-warming, open-top chambers(OTCs) are widely applied for studying the effects of future climate warming on coastal wetlands. In this study, a set of six OTCs were established at a Phragmites wetland located in the Yellow River Delta of Dongying City, China. With data collected through online transmission and in-situ sensors, the attributes and patterns of realized OTCs warming are demonstrated.The authors also quantified the preliminary influence of experimental chamber warming on plant traits.OTCs produced an elevated average air temperature of 0.8°C(relative to controls) during the growing season(June to October) of 2018, and soil temperatures actually decreased by 0.54°C at a depth of 5 cm and 0.46°C at a depth of 30 cm in the OTCs. Variations in diel patterns of warming depend greatly on the heat sources of incoming radiation in the daytime versus soil heat flux at night. Warming effects were often larger during instantaneous analyses and influenced OTCs air temperatures from-2.5°C to 8.3°C dependent on various meteorological conditions at any given time, ranging from cooling influences from vertical heat exchange and vegetation to radiation-associated warming. Night-time temperature depressions in the OTCs were due to the low turbulence inside OTCs and changes in surface soilatmosphere heat transfer. Plant shoot density, basal diameter, and biomass of Phragmites decreased by23.2%, 6.3%, and 34.0%, respectively, under experimental warming versus controls, and plant height increased by 4.3%, reflecting less carbon allocation to stem structures as plants in the OTCs experienced simultaneous wind buffering. While these passive-warming OTCs created the desired warming effects both to the atmosphere and soils, pest damages on the plant leaves and lodging within the OTCs were extensive and serious, creating the need to consider control options for these chambers and the replicated OTCs studies underway in other Chinese Phragmites marshes(Panjin and Yancheng).
文摘Empty steel-tanks are very much susceptible against buckling induced by wind loading.Ring and vertical stiffeners are commonly used to provide necessary strength to thin-walled steel tanks to resist wind-induced buckling.The authors have studied the performance of a unique,ribonucleic acid structure-inspired,stiffening-helix mechanism against the wind-induced buckling of open-top,cylindrical,empty,steel-tank.The most important output parameter of this study is the load multiplier(λ)of buckling,as it defines the stability of tank-shell against wind-induced buckling.The study variables are tank-height to tank-diameter(H/D)ratio,tank-radius to wall-thickness(rlt)ratio,basic wind speed(V)and helix pitch length to tank-height(L_(p)/H)ratio.This study has been performed through multiphysics system-coupling of computational fluid dynamics and structural mechanics(eigenvalue buckling).The stiffening-helix can provide necessary strength to open-top,cylindrical,steel-tank economically against wind-induced buckling.An artificial neural network(ANN)has been trained with the analytical data to develop a predictive model.The proposed predictive ANN model produces 99.11% average accuracy.
基金supported by the National Key Research and Development Program(No.2022YFC3701102)the National Natural Science Foundation of China(Nos.41905109,42405114,and 42105105).
文摘Gaseous nitrous acid(HONO)is a critical contributor to daytime hydroxyl radical in the troposphere.Livestock farming has been recognized as an overlooked HONO source,but the lack of detailed flux measurements from livestock and poultry wastes would cause uncertainties in modeling its environmental impacts.Here,based on field flux measurements and laboratory experiments,we observed substantial HONO emissions from the composting of swine feces and chicken manure in the warm season,which might be mainly attributed to nitrification process in livestock and poultry wastes.The HONO emission from chicken manure was found to bemuch higher than that from swine feces,and the higher NH3 emission but lower N2O and NO emissions fromchicken manurewere also observed.Considering that the interaction among these nitrogen species during nitrification process,the obviously lower HONO emission from swine feces was likely to be explained by the lack of the total ammonia nitrogen and H+donors in swine feces.Temperature is also a key factor that influences the HONO emission from livestock wastes.In addition,the total HONO emission from swine feces in Chinawas estimated to be approximately 107.7 Gg-N/yr according to the national swine amounts,which is comparable to the national soil HONO emissions,underscoring its non-negligible contribution to regional air quality.Therefore,effective emission control of HONO fromlivestock and poultry wastes should be carried out to further improve air quality in China.
文摘在气候变化背景下,探究关中台塬区冬小麦生长发育过程中主要农艺性状及干物质分配对增温的响应特征,对评估冬小麦的敏感性及适应性具有重要意义。本文以冬小麦品种郑麦1860号为研究对象,通过开顶式气室(Open Top Chamber,OTC)模拟增温环境,分析增温对冬小麦生长发育过程的影响。结果表明,在小麦生育期内,气室内外温度存在显著差异(p<0.05),OTC内部平均温度较外部高0.8℃;增温条件下,小麦各物候期平均提前6 d,且株高明显增加。返青—抽穗阶段,OTC对小麦叶面积有促进作用,而扬花—乳熟阶段,则对叶面积有抑制作用。增温促进根系生长,使单株根系长度增加37.48%,细根表面积增加35.28%,但对根系生物量有抑制作用,OTC处理组较对照组减少7.60%;增温对茎、叶和穗的干物质量均有促进作用,但乳熟期叶干物质量例外。OTC增温对冬小麦营养生长期的功能性状具有明显促进作用,但对生殖生长期的功能性状影响不显著,甚至表现出一定的抑制作用。
