人类活动引起的过量氮素输入已经成为引起区域生态环境恶化的主要原因.为探究北京地区人类活动产生的氮素对果园造成的潜在影响,基于大气沉降、肥料、食物/饲料和生物固氮四部分氮素输入之和的人类活动净氮输入(net anthropogenic nitro...人类活动引起的过量氮素输入已经成为引起区域生态环境恶化的主要原因.为探究北京地区人类活动产生的氮素对果园造成的潜在影响,基于大气沉降、肥料、食物/饲料和生物固氮四部分氮素输入之和的人类活动净氮输入(net anthropogenic nitrogen input,NANI)模型,估算了聂各庄果园2018年人类活动导致的净氮输入量.结果显示,研究区域NANI值为234 kg hm^(-2)a^(-1).其中,肥料输入强度为179 kg hm^(-2)a^(-1),占NANI的62.1%;大气沉降输入强度为65 kg hm-2a-1,占NANI的22.5%;其他依次为生物固氮(18 kg hm^(-2)a^(-1);6.1%)和食物/饲料(-27 kg hm^(-2)a^(-1);-9.3%).研究区NANI值偏高,其为我国主要流域NANI值的1.4-3.9倍.肥料是该区域NANI的主要来源,其施用量高出全国和北京地区平均水平的13%和10%.大气氮沉降是NANI的第二大来源,其为全国平均沉降量的4.7倍.肥料和大气沉降都对区域生态环境造成了一定的压力,宜采取相应措施防止多余的氮素流向下游水体.在全国和北京地区平均施肥水平为基准的情况下,通过减少肥料用量17-22 kg hm^(-2)a^(-1)可以有效降低研究区NANI值.通过减少或替换汽油驱动的汽车100万辆,可以减小大气沉降中硝态氮7.16 kg hm^(-2)a^(-1).本研究表明该区域NANI最主要的来源为肥料和大气沉降,通过一系列措施能够对区域内过量的氮素进行消减,达到净化环境的目.(图4表5参40)展开更多
The F-doped O3-type NaNi1/3Fe1/3Mn1/3O2-xFx （x = 0, 0.005, 0.01,002 and noted as NFM-F0, NFM-F0.005, NFM-F0.01, NFM-F0.02, respectively, united as NFM-Fs） cathode materials were investigated systematically. The rate...The F-doped O3-type NaNi1/3Fe1/3Mn1/3O2-xFx （x = 0, 0.005, 0.01,002 and noted as NFM-F0, NFM-F0.005, NFM-F0.01, NFM-F0.02, respectively, united as NFM-Fs） cathode materials were investigated systematically. The rate performance and capacity retention of the O3-type cathode materials are significantly improved as a function of specific F-doping levels. Optimum performance is achieved in the NFM-F0.01 material having a capacity of -110mAhg-1 at a current density of 150mAg-1 after 70 cycles. The results indicate that the binding energy of oxygen changes as a result of F-doping, and in addition, F-doping results in changes to the stoichiometry of Mn3＋/Mn4＋, which stabilizes the O3-type layered structure, thus allowing cycling performance to be improved. However, NFM-F0.02, having a higher F-doping level, retains a high capacity retention, although a slight loss is observed. The results suggest there is an optimum F-doping level for the NFM-F system to deliver enhanced cycling performance.展开更多
文摘人类活动引起的过量氮素输入已经成为引起区域生态环境恶化的主要原因.为探究北京地区人类活动产生的氮素对果园造成的潜在影响,基于大气沉降、肥料、食物/饲料和生物固氮四部分氮素输入之和的人类活动净氮输入(net anthropogenic nitrogen input,NANI)模型,估算了聂各庄果园2018年人类活动导致的净氮输入量.结果显示,研究区域NANI值为234 kg hm^(-2)a^(-1).其中,肥料输入强度为179 kg hm^(-2)a^(-1),占NANI的62.1%;大气沉降输入强度为65 kg hm-2a-1,占NANI的22.5%;其他依次为生物固氮(18 kg hm^(-2)a^(-1);6.1%)和食物/饲料(-27 kg hm^(-2)a^(-1);-9.3%).研究区NANI值偏高,其为我国主要流域NANI值的1.4-3.9倍.肥料是该区域NANI的主要来源,其施用量高出全国和北京地区平均水平的13%和10%.大气氮沉降是NANI的第二大来源,其为全国平均沉降量的4.7倍.肥料和大气沉降都对区域生态环境造成了一定的压力,宜采取相应措施防止多余的氮素流向下游水体.在全国和北京地区平均施肥水平为基准的情况下,通过减少肥料用量17-22 kg hm^(-2)a^(-1)可以有效降低研究区NANI值.通过减少或替换汽油驱动的汽车100万辆,可以减小大气沉降中硝态氮7.16 kg hm^(-2)a^(-1).本研究表明该区域NANI最主要的来源为肥料和大气沉降,通过一系列措施能够对区域内过量的氮素进行消减,达到净化环境的目.(图4表5参40)
基金supported by the National High-Tech R&D Program of China (2015AA034601, 2016YFB010030X, and 2016YFB0700600)the State Key Laboratory of Materials Processing and Die & Mould Technologythe Analytical and Testing Center of Huazhong University of Science Technology
文摘The F-doped O3-type NaNi1/3Fe1/3Mn1/3O2-xFx （x = 0, 0.005, 0.01,002 and noted as NFM-F0, NFM-F0.005, NFM-F0.01, NFM-F0.02, respectively, united as NFM-Fs） cathode materials were investigated systematically. The rate performance and capacity retention of the O3-type cathode materials are significantly improved as a function of specific F-doping levels. Optimum performance is achieved in the NFM-F0.01 material having a capacity of -110mAhg-1 at a current density of 150mAg-1 after 70 cycles. The results indicate that the binding energy of oxygen changes as a result of F-doping, and in addition, F-doping results in changes to the stoichiometry of Mn3＋/Mn4＋, which stabilizes the O3-type layered structure, thus allowing cycling performance to be improved. However, NFM-F0.02, having a higher F-doping level, retains a high capacity retention, although a slight loss is observed. The results suggest there is an optimum F-doping level for the NFM-F system to deliver enhanced cycling performance.
