利用静态箱-气相色谱法,研究了氮输入对闽江河口短叶茳芏湿地CH4和N2O排放通量的短期影响.结果表明,高氮输入在不同采样时间均促进了湿地CH4排放,低氮输入在不同时间则具有不同的变化特征.与对照处理相比,低氮和高氮2种处理分别使湿地CH...利用静态箱-气相色谱法,研究了氮输入对闽江河口短叶茳芏湿地CH4和N2O排放通量的短期影响.结果表明,高氮输入在不同采样时间均促进了湿地CH4排放,低氮输入在不同时间则具有不同的变化特征.与对照处理相比,低氮和高氮2种处理分别使湿地CH4排放通量增加了-44.35%～1 057.35%和7.15%～667.37%.外源氮输入在24 h内对湿地N2O排放通量具有明显的正激发效应,最高可增加171.60倍和177.79倍,但在8 d后,氮输入对湿地N2O排放的激发效应减弱甚至消失.氮输入在短时间内对湿地土壤Ec、pH和Eh均未产生显著影响.湿地CH4排放通量在对照处理下仅与5 cm Eh存在显著负相关,在低氮处理下仅与10 cm地温呈显著负相关,在高氮处理下则与5 cm Ec、0、5 cm pH以及0、5、10 cm土壤Eh均呈显著相关性,而N2O排放通量在不同处理下与湿地气温、地温、盐度、pH和Eh等环境因子均不存在显著相关性.研究表明,探讨氮输入对湿地温室气体排放的影响应考虑其时间变异性.展开更多
Increasing salt-affected agricultural land due to low precipitation, high surface evaporation, irrigation with saline water, and poor cultural practices has triggered the interest to understand the influence of salt o...Increasing salt-affected agricultural land due to low precipitation, high surface evaporation, irrigation with saline water, and poor cultural practices has triggered the interest to understand the influence of salt on nitrous oxide （N20） and carbon dioxide （CO2） emissions from soil. Three soils with varying electrical conductivity of saturated paste extract （ECe） （0.44-7.20 dS m-1） and sodium adsorption ratio of saturated paste extract （SARe） （1.1-27.7）, two saline-sodic soils （S2 and S3） and a non-saline, non-sodic soil （S1）, were incubated at moisture levels of 40%, 60%, and 80% water-filled pore space （WFPS） for 30 d, with or without nitrogen （N） fertilizer addition （urea at 525μg g-1 soil）. Evolving CO2 and N20 were estimated by analyzing the collected gas samples during the incubation period. Across all moisture and N levels, the cumulative N20 emissions increased significantly by 39.8% and 42.4% in S2 and S3, respectively, compared to S1. The cumulative CO2 emission from the three soils did not differ significantly as a result of the complex interactions of salinity and sodicity. Moisture had no significant effect oi1 N20 emissions, but cumulative CO2 emissions increased significantly with an increase in moisture. Addition of N significantly increased cumulative N20 and CO2 emissions. These showed that saline-sodic soils can be a significant contributor of N20 to the environment compared to non-saline, non-sodic soils. The application of N fertilizer, irrigation, and precipitation may potentially increase greenhouse gas （N20 and CO2） releases from saline-sodic soils.展开更多
Agricultural production plays an important role in affecting atmospheric nitrous oxide （N20） concentrations. Field measurements were conducted in Dalian City, Liaoning Province in Northeast China from two consecutiv...Agricultural production plays an important role in affecting atmospheric nitrous oxide （N20） concentrations. Field measurements were conducted in Dalian City, Liaoning Province in Northeast China from two consecutive years （2009 and 2010） to estimate NzO emissions from a spring maize field, a main cropping system across the Chinese agricultural regions. The observed flux data in conjunction with the local climate, soil and management information were utilized to test a process-based model, DeNitrification-DeComposition （DNDC）, for its applicability for the cropping system. The validated DNDC was then used for exploring strategies to reduce N20 emissions from the target field. The results showed that the major N20 pulse emissions occurred with duration of about 3-5 d after fertilizer application in both years 2009 and 2010, which on average accounted for about 60% of the total N20 emissions each year. Rainfall and fertilizer application were the major factors influencing the N20 emissions from spring maize field. The average N20 flUXeS from the CK （control plot, without fertilization） and FP （traditional chemical N fertilizer） treatments were 23.1 and 60.6 gg m-2 h-~ in 2009, respectively, and 21.5 and 64.3 gg m-2 h-~ in 2010, respectively. The emission factors （EFs） of the applied N fertilizer （270 kg N ha-1） as N20- N were 0.62% in 2009 and 0.77% in 2010, respectively. The comparison of modeled daily NzO emission fluxes against observations indicated that the DNDC model had a good performance even if without adjusting the internal parameters. The modeled results showed that management practices such as no-till, changing timing or rate of fertilizer application, increasing residue incorporation, and other technically applicable measures could effectively reduce N20 emissions from the tested fields. Our study indicated that avoiding application of N fertilizers at heavy rainfall events or splitting the fertilizer into more applications would be the most feasible approaches to reduce N20展开更多
Single-atom catalysts(SACs)have attracted extensive attention in the field of heterogeneous catalysis.However,the fabrication of SACs with high loading and hightemperature stability remains a grand challenge,especiall...Single-atom catalysts(SACs)have attracted extensive attention in the field of heterogeneous catalysis.However,the fabrication of SACs with high loading and hightemperature stability remains a grand challenge,especially on oxide supports.In this work,we have demonstrated that through strong covalent metal-support interaction,highloading and thermally stable single-atom Pt catalysts can be readily prepared by using Fe modified spinel as support.Better catalytic performance in N2O decomposition reaction is obtained on such SACs than their nanocatalyst counterpart and low-surface-area Fe2O3 supported Pt SACs.This work provides a strategy for the fabrication of high-loading and thermally stable SACs for applications at high temperatures.展开更多
文摘利用静态箱-气相色谱法,研究了氮输入对闽江河口短叶茳芏湿地CH4和N2O排放通量的短期影响.结果表明,高氮输入在不同采样时间均促进了湿地CH4排放,低氮输入在不同时间则具有不同的变化特征.与对照处理相比,低氮和高氮2种处理分别使湿地CH4排放通量增加了-44.35%～1 057.35%和7.15%～667.37%.外源氮输入在24 h内对湿地N2O排放通量具有明显的正激发效应,最高可增加171.60倍和177.79倍,但在8 d后,氮输入对湿地N2O排放的激发效应减弱甚至消失.氮输入在短时间内对湿地土壤Ec、pH和Eh均未产生显著影响.湿地CH4排放通量在对照处理下仅与5 cm Eh存在显著负相关,在低氮处理下仅与10 cm地温呈显著负相关,在高氮处理下则与5 cm Ec、0、5 cm pH以及0、5、10 cm土壤Eh均呈显著相关性,而N2O排放通量在不同处理下与湿地气温、地温、盐度、pH和Eh等环境因子均不存在显著相关性.研究表明,探讨氮输入对湿地温室气体排放的影响应考虑其时间变异性.
文摘Increasing salt-affected agricultural land due to low precipitation, high surface evaporation, irrigation with saline water, and poor cultural practices has triggered the interest to understand the influence of salt on nitrous oxide （N20） and carbon dioxide （CO2） emissions from soil. Three soils with varying electrical conductivity of saturated paste extract （ECe） （0.44-7.20 dS m-1） and sodium adsorption ratio of saturated paste extract （SARe） （1.1-27.7）, two saline-sodic soils （S2 and S3） and a non-saline, non-sodic soil （S1）, were incubated at moisture levels of 40%, 60%, and 80% water-filled pore space （WFPS） for 30 d, with or without nitrogen （N） fertilizer addition （urea at 525μg g-1 soil）. Evolving CO2 and N20 were estimated by analyzing the collected gas samples during the incubation period. Across all moisture and N levels, the cumulative N20 emissions increased significantly by 39.8% and 42.4% in S2 and S3, respectively, compared to S1. The cumulative CO2 emission from the three soils did not differ significantly as a result of the complex interactions of salinity and sodicity. Moisture had no significant effect oi1 N20 emissions, but cumulative CO2 emissions increased significantly with an increase in moisture. Addition of N significantly increased cumulative N20 and CO2 emissions. These showed that saline-sodic soils can be a significant contributor of N20 to the environment compared to non-saline, non-sodic soils. The application of N fertilizer, irrigation, and precipitation may potentially increase greenhouse gas （N20 and CO2） releases from saline-sodic soils.
基金funded by the Special Fund for Agriculture-Scientific Non-Profit Research, China(201103039)the National Basic Research Program of China(2012CB417104)by the Basic R&D Operations Special Fund forthe Central Level Non-Profit Research Institute of China(2012-35)
文摘Agricultural production plays an important role in affecting atmospheric nitrous oxide （N20） concentrations. Field measurements were conducted in Dalian City, Liaoning Province in Northeast China from two consecutive years （2009 and 2010） to estimate NzO emissions from a spring maize field, a main cropping system across the Chinese agricultural regions. The observed flux data in conjunction with the local climate, soil and management information were utilized to test a process-based model, DeNitrification-DeComposition （DNDC）, for its applicability for the cropping system. The validated DNDC was then used for exploring strategies to reduce N20 emissions from the target field. The results showed that the major N20 pulse emissions occurred with duration of about 3-5 d after fertilizer application in both years 2009 and 2010, which on average accounted for about 60% of the total N20 emissions each year. Rainfall and fertilizer application were the major factors influencing the N20 emissions from spring maize field. The average N20 flUXeS from the CK （control plot, without fertilization） and FP （traditional chemical N fertilizer） treatments were 23.1 and 60.6 gg m-2 h-~ in 2009, respectively, and 21.5 and 64.3 gg m-2 h-~ in 2010, respectively. The emission factors （EFs） of the applied N fertilizer （270 kg N ha-1） as N20- N were 0.62% in 2009 and 0.77% in 2010, respectively. The comparison of modeled daily NzO emission fluxes against observations indicated that the DNDC model had a good performance even if without adjusting the internal parameters. The modeled results showed that management practices such as no-till, changing timing or rate of fertilizer application, increasing residue incorporation, and other technically applicable measures could effectively reduce N20 emissions from the tested fields. Our study indicated that avoiding application of N fertilizers at heavy rainfall events or splitting the fertilizer into more applications would be the most feasible approaches to reduce N20
基金supported by the National Key Projects for Fundamental Research and Development of China(2016YFA0202801)the National Natural Science Foundation of China(21673226+3 种基金91645203 and 21590792)the “Transformational Technologies for Clean Energy and Demonstration”the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA21040200 and XDB17000000)supported by the Tsinghua Xuetang Talents Program
文摘Single-atom catalysts(SACs)have attracted extensive attention in the field of heterogeneous catalysis.However,the fabrication of SACs with high loading and hightemperature stability remains a grand challenge,especially on oxide supports.In this work,we have demonstrated that through strong covalent metal-support interaction,highloading and thermally stable single-atom Pt catalysts can be readily prepared by using Fe modified spinel as support.Better catalytic performance in N2O decomposition reaction is obtained on such SACs than their nanocatalyst counterpart and low-surface-area Fe2O3 supported Pt SACs.This work provides a strategy for the fabrication of high-loading and thermally stable SACs for applications at high temperatures.
