key: cord-0999255-dexfrraj
authors: Huang, Jianping; Zhao, Yingjie; Wang, Danfeng
title: Possible link between new coronavirus variants and atmospheric lightning and seawater intrusion
date: 2021-11-24
journal: Atmospheric and Oceanic Science Letters
DOI: 10.1016/j.aosl.2021.100135
sha: f36200a1b00e7842e2fe7612713abff42a988339
doc_id: 999255
cord_uid: dexfrraj

SARS-CoV-2 (COVID-19) has been affecting the world for more than one year. The appearance of the new coronavirus variants makes the current situation full of uncertainty. In this respect, we discuss the connection between virus mutation and atmospheric factors. Based on the process of nitrogen fixation and transformation of nitrate inside the human body, we propose that the new coronavirus variants might be related to lightning and seawater intrusion. Our study provides a new perspective in terms of the possible mechanism underlying the emergence of new coronavirus variants.

identified in Kent in the UK, there have been four further main lineages identified so farnamely, Beta lineage (Nelson Mandela Bay, South Africa), Gamma lineage (Manaus, Brazil), Eta lineage (Osun, Nigeria and the UK), and Delta lineage (Maharashtra, India). So, including Alpha lineage, five new variants in total. The new features of these new variants, such as higher transmissibility and antibody resistance, have led to them spreading rapidly throughout the world, and might cause a third wave of the pandemic (Zhao et al., 2021) .

The principles of virus mutation have been widely investigated by biologists. From the biological perspective, mutation happens when the structure of RNA is destroyed. Nitric oxide (NO) plays an important role in the immune system (Bogdan, 2001) , but overproduction of NO can cause health problems for humans-for example, it can cause RNA mutation inside human cells (Wurtmann and Wolin, 2009) . Researchers have put a great deal of effort into studying the underlying mechanism of mutation from a biological point of view. However, the relationship between the environment and mutation has rarely been mentioned. Inspired by the idea that NO can cause RNA mutation, we studied the generation of NO from the environmental perspective, and discuss here the possible mechanism underlying the appearance of new coronavirus variants.

It has been proven that high concentrations of nitrate in the human body can increase the risk of health problems. Researchers have found that oxidative stress induced by NO can accelerate the mutation of virus RNA, including that of HIV, influenza virus, and Sendai virus (Akaike and Maeda, 2000; . NO, as a free radical inside cells, is involved in physiological and pathological conditions, whereas overproduction of free radicals can cause damage to cells, thus leading to mutation (Phaniendra et al., 2014) . Figure 1 illustrates the process of nitrogen fixation and transformation of nitrate inside the human body. The circulation of NO follows a nitrate-nitrite-nitric oxide (NO 3 − -NO 2 − -NO) pathway inside the human body (Lundberg and Weitzberg, 2008; Weitzberg et al., 2021) . Dietary intake, such as green leafy vegetables, drinking water, and cured meat, is considered the main source of nitrate (Wu et al., 2019) . Nitrate can be reduced to nitrite by oral commensal bacteria, and the nitrite in blood and tissues will then be transformed to NO by certain enzymes in tissues (Lundberg and Weitzberg, 2008) . Other than following the NO circulation, NO synthase (NOS) is another source of NO for humans, where NO is produced directly by NOS in cells (Forstermann and Sessa, 2011) . Nitrogen circulation in nature indicates that when lightning takes place, the high temperatures it produces can break the nitrogen in the air into nitrogen oxides (NO x ), which will dissolve in rain and combine with oxygenated water in the rain to turn into nitrate. Nitrate will be carried down to earth, and becomes the natural fertilizer for plants. Other than lightning-produced NO x entering the human body, sea water also contains large quantities of NO x. We researched geographical information on each location and found that some of the places are located along the coastline, such as Kent (UK), Nelson Mandela Bay (South Africa), and California (USA). Underground water is an important water resource for people who live near the coastline. Researchers have pointed out that the concentration of nitrate in coastal groundwater is high (Ma et al., 2018) , suggesting that people living near the coastline can face nitrate pollution issues. This finding might partly explain the fact that most of the new coronavirus variants were found in places located along the coastline. Nitrogen oxides produced by lightning contribute an important part to the total NO x budget, and sometimes even become the dominant source of NO x (Labrador et al., 2005) . It was found that the lightning activity in Manaus city (Brazil) has been increasing throughout the last four decades (Pinto Jr. et al., 2013) . The coastal areas of Japan are more likely to be hit by lightning in winter (Matsui et al., 2020) . It has been recorded that Kent suffers from a high frequency of thunderstorms in the UK (Lees, 1997) . South Africa is one of the countries most frequently bit by lightning, especially in summer (October to March) (Gijben, 2012) . These areas are all the original places for the new coronavirus variants, and were hit by lightning frequently at the same time.

These findings suggest that it is worthwhile investigating the relationship between COVID-19 and environmental factors. Our study provides a link between the atmosphere and virus mutation, but as a preliminary investigation of course has its limitations. For example, the sources of atmospheric NOx are various; transportation, power plants, and industrial activity will also produce NO x . In some areas, these sources might contribute more NO x than lightning does.

Moreover, lightning and seawater intrusion may not necessarily cause the virus mutation, but promote the possibility. Nonetheless, our study highlights a new direction for researchers to elucidate more connections between environmental factors and virus mutation in the future.

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Fig. 1. The process of nitrate-nitrite circulation from nature into the human body