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首页> 外文期刊>Journal of the air & waste management association >Influence of deployment time and surface wind speed on the accuracy of measurements of greenhouse gas fluxes using a closed chamber method under low surface wind speed
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Influence of deployment time and surface wind speed on the accuracy of measurements of greenhouse gas fluxes using a closed chamber method under low surface wind speed

机译：低表面风速下密闭室法的展开时间和地面风速对温室气体通量测量精度的影响

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摘要

As a convenient method, the closed chamber method has been applied to determine gaseous emission fluxes from fully open animal feeding operations despite the measured fluxes being theoretically affected by deployment time, wind speed over the emitting surface and detected gas mass. This laboratory study evaluated the effects of deployment time (0 to 120 min) and external surface wind speed (ESWS) (0.00, 0.25, 0.50, 0.75, 1.00, 1.50 and 2.00 m sec(-1)) on the measurement accuracy of a 300 mm (diameter) x 400 mm (height) (D300xH400) closed chamber using methane (CH4), nitrous oxide (N2O) and sulfur hexafluoride (SF6) as reference gases. The results showed that the overall deviation ratio between the measured and reference CH4 fluxes ranged from 9.99 % to -37.32 % and the flux was overestimated in the first 20 min. The measured N2O and SF6 emissions were smaller than the reference fluxes using the chamber. N2O measurement accuracy decreased from -14.47 to -35.09% with deployment time extended to 120 min, while SF6 accuracy sharply increased in the first 40 min, with the deviation stabilizing at approximately -5.00%. CH4, N2O and SF6 measurements were significantly affected by deployment time and ESWS (P0.05), and the interaction of those two factors greatly influenced CH4 and SF6 measurements (P0.05). With the D300xH400 closed chamber, deployment times of 20 to 30 min and 10 to 20 min are recommended to measure CH4 and N2O, respectively, from the open operations of dairy farms under wind speeds lower than 2 m sec(-1).Implications: This study recommended the suitable deployment times and wind speeds for using a D300 x H400 closed chamber to measure CH4, N2O, and SF6 in an open system, such as a dairy open lot and manure stockpile, to help researchers and other related industry workers get accurate data for gas emission rate. Deployment times of 20 to 30 min and 10 to 20 min were recommended to measure CH4 and N2O emissions using the D300 x H400 closed chamber, respectively, from the open operations of dairy farms under wind speeds lower than 2 m sec(-1). For the measurement of SF6, a typical tracer gas, a deployment of 70 to 90 min was suggested.
机译：作为一种方便的方法，尽管理论上受部署时间，发射表面的风速和检测到的气体质量的影响，但已采用密闭室法确定来自完全开放式动物饲养操作的气体排放通量。这项实验室研究评估了部署时间（0至120分钟）和外表面风速（ESWS）（0.00、0.25、0.50、0.75、1.00、1.50和2.00 m sec（-1））对传感器测量精度的影响。 300毫米（直径）x 400毫米（高度）（D300xH400）密闭室，使用甲烷（CH4），一氧化二氮（N2O）和六氟化硫（SF6）作为参考气体。结果表明，测得的CH4通量和参考CH4通量之间的总偏差率为9.99％至-37.32％，并且在前20分钟内通量被高估了。使用该腔室测得的N2O和SF6排放量小于参考通量。随着部署时间延长至120分钟，N2O的测量精度从-14.47降低到-35.09％，而SF6精度在前40分钟内急剧增加，偏差稳定在大约-5.00％。 CH4，N2O和SF6的测量值受到部署时间和ESWS的显着影响（P <0.05），而这两个因素的相互作用极大地影响了CH4和SF6的测量值（P <0.05）。对于D300xH400密闭室，建议在风速低于2 m sec（-1）时从奶牛场的开放操作中分别测量20至30分钟和10至20分钟的部署时间来测量CH4和N2O。这项研究建议在D300 x H400密闭室中使用合适的部署时间和风速来测量开放系统（例如奶牛场和粪便）中的CH4，N2O和SF6，以帮助研究人员和其他相关行业工人气体排放率的准确数据。建议使用D300 x H400密闭室分别以20到30分钟和10到20分钟的部署时间来测量CH4和N2O排放，该密闭室是在风速低于2 m sec（-1）的情况下从奶牛场的开放操作中测量的。对于SF6（一种典型的示踪气体）的测量，建议部署70至90分钟。

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    Liu Yu; Wang Chaoyuan; Ding Luyu; Wang Zixin; Teng Guanghui; Shi Zhengxiang; Li Baoming;

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    China Agr Univ, Coll Water Resources & Civil Engn, Dept Agr Struct & Bioenvironm Engn, Beijing, Peoples R China|Minist Agr & Rural Affairs, Key Lab Agr Engn Struct & Environm, Beijing, Peoples R China;

    China Agr Univ, Coll Water Resources & Civil Engn, Dept Agr Struct & Bioenvironm Engn, Beijing, Peoples R China|Minist Agr & Rural Affairs, Key Lab Agr Engn Struct & Environm, Beijing, Peoples R China;

    Natl Engn Res Ctr Informat Technol Agr, Beijing, Peoples R China;

    China Agr Univ, Coll Water Resources & Civil Engn, Dept Agr Struct & Bioenvironm Engn, Beijing, Peoples R China;

    China Agr Univ, Coll Water Resources & Civil Engn, Dept Agr Struct & Bioenvironm Engn, Beijing, Peoples R China|Minist Agr & Rural Affairs, Key Lab Agr Engn Struct & Environm, Beijing, Peoples R China;

    China Agr Univ, Coll Water Resources & Civil Engn, Dept Agr Struct & Bioenvironm Engn, Beijing, Peoples R China|Minist Agr & Rural Affairs, Key Lab Agr Engn Struct & Environm, Beijing, Peoples R China;

    China Agr Univ, Coll Water Resources & Civil Engn, Dept Agr Struct & Bioenvironm Engn, Beijing, Peoples R China|Minist Agr & Rural Affairs, Key Lab Agr Engn Struct & Environm, Beijing, Peoples R China;

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