TROPOMI Monitoring of NO2 Sources and Spread during the Beirut 2020 Seaport Ammonium Nitrate Explosion

TROPOMI Monitoring of NO₂ Sources and Spread during the Beirut 2020 Seaport  Ammonium Nitrate Explosion

 

Nayla El-Kork1,2, Ashraf Farahat3

1Space and Planetary Science Center, Khalifa University,P.O. Box 127788, Abu Dhabi, United Arab Emirates;

nayla.elkork@ku.ac.ae 

2Department of Physics, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates;

3Department of Physics, College of Engineering and Physics, King Fahd University of Petroleum, & Minerals, Dhahran 31261, Saudi Arabia.; ashraf.farahat@kfupm.edu.sa 

Ammonium nitrate (NH₄NO₃) is a white crystalline solid chemical compound consisting of ions of ammonium and is commonly used as a high-nitrogen garden and farm fertilizer. Ammonium nitrate can trigger explosions if exposed to a temperature above 190 °C. More than thirty ammonium nitrate accidents have occurred since the beginning of the 19th century, including explosions in the United Kingdom (1916), Germany (1921), the United States (1942, 1947, and 2013), France (2001), and China (2015).  The most recent massive explosion occurred on August 4, 2020, in Beirut, Lebanon. The explosion killed over 200 people, injured about 7,000, damaged significant properties in Beirut, and loaded large amounts of particulate matter, dust, and toxic gases into the atmosphere. 

In this work, we use NO2 measurements from the Level 2 NO2 TROPOspheric Monitoring Instrument (TROPOMI), onboard S5P (100 – 700 nm) to investigate the generation of the toxic NO2 gas during the Beirut explosion. Interestingly a high NO2 emission over Beirut was observed from 28 July – 3 August 2020, a few days before the Beirut blast, with the highest emission on 28 July. This high NO2 background is attributed to many reasons: vehicle and ship emissions and the armed conflict in Syria. To confirm the possible effects of vehicles and ships in increasing NO2 loading in the atmosphere, the NO2 emission from Cairo, Egypt (known for its high population and high traffic volume); Nicosia, Cyprus (known for its low population and low traffic volume); and Suez Canal, Egypt (known for its high ship traffic and high traffic volume) are compared to Beirut NO2 emissions. Meanwhile, to understand the spatiotemporal distribution of NO2 (before, during, and after the explosion), the emission is examined in seven locations with four coastal (Beirut, Jounieh, Batron, and Tripoli) and three inland cities (Ehden, Baalbek, and Ain El Bnaiyyeh) in Lebanon. Results indicate that although NO2 was emitted during the Beirut blast, its amount was not significantly high, and it only affected some of the coastal locations within 20 – 25 km of Beirut, while it did not seem to affect the inland regions. The reported NO2 emission from the explosion could be overestimated, as there is an already high NO2 background in Beirut from vehicles, ships, and the armed conflict in Syria.