The reason why the giant meteorite that boiled the oceans when it collided with Earth 3.2 billion years ago is called the "fertilizer bomb" (2/2)

 Recently CNN.co.jp reported the following:

３２億年前の地球衝突で海を沸騰させた巨大隕石、「肥料爆弾」と呼ばれる理由とは (2/2)

2025.02.07 Fri posted at 20:00 JST

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しかし、深海の状況は海上とは異なっていた。津波で鉄などの成分が巻き上げられ、海面に浮上した。また浸食により、沿岸のごみが洗い流され、隕石に含まれていたリンが放出された。実験室での分析から、隕石の衝突直後に鉄やリンを栄養源とする単細胞生物が急増したことが分かっている。

ドラボン氏によると、生命体は急速に回復し、その後繁栄したという。

ドラボン氏は「隕石の衝突前も、海には多少の生物は生息していたが、それほど多くはなかった。これは、浅海で栄養素や鉄のような電子供与体が不足していたためだ」と述べ、さらに次のように続けた。

「しかし、隕石の衝突でリンなどの重要な栄養素が世界規模で放出された。ある学生はこの衝突を『肥料爆弾』と表現した。全体的に見ると、これは地球上の初期生命体の進化にとって非常に良いニュースだ。なぜなら、生命の進化の初期段階では隕石の衝突が現在よりもはるかに頻繁に起こっていたからだ」

 

衝突の影響はさまざま

Ｓ２と小惑星チクシュルーブの衝突は、異なる結果をもたらしたが、これは隕石の大きさや、衝突時の地球の環境の違いによるものだ、とドラボン氏は説明する。

チクシュルーブ衝突体は、地球の炭酸塩プラットフォームに衝突し、大気中に硫黄を放出した。この硫黄がエアロゾルを形成し、地表の気温を急激かつ極端に低下させた。

そして、どちらの衝突でも、多くの生命体が死滅したが、Ｓ２の衝突の後、浅瀬に生息する太陽光依存型の頑強な微生物は、海が再び満たされ、塵が沈んだ後、急速に回復しただろうとドラボン氏は推測する。

ドラボン氏は、「Ｓ２衝突時の生命ははるかにシンプルだった」とし、「朝、歯を磨くと、口の中の細菌を９９．９％除去できるかもしれないが、夕方までに元に戻っている」と付け加えた。

Translation

The giant meteorite that boiled the oceans when it collided with Earth 3.2 billion years ago: why it's called a "fertilizer bomb" (2/2)

2025.02.07 Fri posted at 20:00 JST

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However, the situation in the deep sea was different from that above the sea. The tsunami stirred up elements such as iron and brought them to the surface. Erosion also washed away coastal trash, releasing the phosphorus contained in the meteorite. Laboratory analysis has shown that immediately after the meteorite's impact, single-celled organisms that used iron and phosphorus as a source of nutrition rapidly increased.

According to Drabon, the life that was formed recovered quickly and then thrived.

"Even before the meteorite's impact, there were some organisms in the ocean, but not many. This was because in shallow waters there was a shortage of nutrients and electron donors such as iron," Dravon said, and continued:

"But the impact released important nutrients, such as phosphorus, on a global scale. One student described the impact as a 'fertilizer bomb.' Overall, this is very good news for the evolution of early life on Earth. That's because meteorite impacts were much more frequent in the early stages of the evolution of life than they are today."

Different impact effects

The impacts of S2 and the Chicxulub asteroid had different outcomes, due to the size of the meteorites and the different environments on Earth at the time of impact, Drabon explained.

The Chicxulub impactor struck the Earth's carbonate platform, releasing sulfur into the atmosphere. This sulfur formed aerosols that caused a sudden and extreme drop in surface temperatures.

And while many life forms were killed in both impacts, Drabon speculated that after the S2 impact, the tough, sunlight-dependent microorganisms that lived in shallow waters would have recovered quickly after the oceans refilled and the dust sank.

"Life was by far much simpler when the S2 hit," Dravon said, adding, "Brushing your teeth in the morning might remove 99.9 percent of the bacteria in your mouth, but by the evening it's all back."

              So, according to the latest theory, the impacts of S2 and the Chicxulub asteroid had different outcomes, due to the size of the meteorites and the different environments on Earth at the time of impact. While many life forms were killed in both impacts, scientists speculate that after the S2 impact, the microbes living in shallow waters could recover quickly, and single-celled organisms that use iron and phosphorus as a source of nutrition rapidly increased. Apparently, S2 has turned an important chapter in the development of life on earth.