北京-天津間の農村地帯におけるCOVID-19パンデミックの制御期間中の1時間ごとのPM関連元素のレベルと発生源

Levels and sources of hourly PM-related elements during the control period of the COVID-19 pandemic at a rural site between Beijing and Tianjin.

• Yang Cui
• Dongsheng Ji
• Willy Maenhaut
• Wenkang Gao
• Renjian Zhang
• Yuesi Wang

抄録

中国における新型コロナウイルス病2019（COVID-19）の蔓延を抑制するために、国家規模で多くの人為的活動が削減され、さらには閉鎖された。この削減と閉鎖の影響を調べるために、すべての人々が自宅で社会的に隔離されたままで、仕事のために経済圏に戻ることができないコントロール期間の前（2020年1月12日～25日）、期間中（2020年1月26日～2月9日）、期間後（2020年3月22日～4月2日）の1時間ごとのPM関連要素の濃度を農村部のサイトで測定した。正の行列因数分解モデルにより、花火燃焼、石炭燃焼、自動車排出ガス、粉塵、Cr工業、石油燃焼、Se工業、Zn製錬所、鉄鋼業を含む9つの主要な発生源が特定された。制御期間前は、K, Fe, Ca, Zn, Ba, Cuが主な元素であり、花火燃焼、Zn製錬所、自動車排出物の寄与度が最も高く、それぞれ55%、12.1%、10.3%であった。対照期間中は、K, Fe, Ba, Cu, Znが主な元素で、花火の燃焼と車両からの排出物が全元素量の55%と27%の寄与を示した。対照期間後は、Fe、K、Ca、Zn、Baが主な元素であり、粉塵と鉄鋼業が全元素量の56％、21％を占めた。対照期間中に自動車からの寄与が増加したのは、サンプリング地点が町の病院の近くにあったことと、自動車の活動が制限されていなかったためであると考えられる。排出源の配分結果は、大気質量の後方軌道にも関連していた。塵埃、石炭燃焼、産業発生源（Cr産業、Zn製錬所、Se産業、鉄鋼業）の最大の減少は、北西部輸送（ウランカブ）で顕著に見られ、北東部輸送（唐山と天津）では最も有意ではなかった。

To control the spread of the novel coronavirus disease 2019 (COVID-19) in China, many anthropogenic activities were reduced and even closed on the national scale. To study the impact of this reduction and closing down, hourly concentrations of PM-related elements were measured at a rural site before (12-25 January 2020), during (26 January-9 February 2020) and after (22 March-2 April 2020) the control period when all people remained socially isolated in their homes and could not return to economic zones for work. Nine major sources were identified by the positive matrix factorization model, including fireworks burning, coal combustion, vehicle emissions, dust, Cr industry, oil combustion, Se industry, Zn smelter, and iron and steel industry. Before the control period, K, Fe, Ca, Zn, Ba and Cu were the main elements, and fireworks burning, Zn smelter and vehicle emissions provided the highest contributions to the total element mass with 55%, 12.1% and 10.3%, respectively. During the control period, K, Fe, Ba, Cu and Zn were the dominating elements, and fireworks burning and vehicle emissions contributed 55% and 27% of the total element mass. After the control period, Fe, K, Ca, Zn and Ba were the main elements, and dust and iron and steel industry were responsible for 56% and 21% of the total element mass. The increased contribution from vehicle emissions during the control period could be attributed to our sampling site being near a town hospital and the fact that the vehicle activities were not restricted. The source apportionment results were also related to air mass backward trajectories. The largest reductions of dust, coal combustion, and the industrial sources (Cr industry, Zn smelter, Se industry, iron and steel industry) were distinctly seen for northwest transport (Ulanqab) and were least significant for northeast transport (Tangshan and Tianjin).

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