What is the fine-grained topic of the following text: According to a new study by researchers at the Japanese Meteorological Research Institute and Tohoku University, the asteroid site had an unusually high concentration of hydrocarbons and sulfur in comparison with most other places on Earth, meaning that its impact was more deadly than it would have been had it struck somewhere else. Only return the topic.
Impact of asteroid site's high concentration of hydrocarbons and sulfur on its deadliness