# Signatures of acid rain at KT boundary

I read in Walter Alvarez' book T. Rex and the Crater of Doom that the Earth's collision with the large meteor leading to the K-T extinction catalyzed the reaction of atmospheric oxygen and nitrogen molecules to form nitric oxide, which in turn formed highly corrosive nitric acid when combined with water. In addition the impact is thought to have volatilized huge amounts of sulfur contained in anhydrite, which in turn formed sulfuric acid.

This question refers to a thickness of $$\pu{1.8m}$$ for the section where iridium could be detected in the K-T boundary, suggesting that the resolution may be too low to note the effects of acid rain following the collision.

Is there evidence in the geological record of the formation of these acid species thought to be associated with the collision, say from deposits and/or effects of the ensuing acid rain?

• Hi @Buck Thorn, you are committed to Materials Modeling Stack Exchange but your commitment won't count until you click the verification link in your email. We know you haven't done this because when you do, your reputation on Area51 will go from 101 to 151 (the default minimum reputation for someone with a confirmed email address). I contact you because we have only 7 days left before the proposal gets completely shut down if we don't get enough committers: area51.stackexchange.com/users/208434/buck-thorn – user1271772 Apr 11 '20 at 22:18
• thank you!!! It worked. We're at 88% now. Best day of my life :) – user1271772 Apr 12 '20 at 19:07
• Indirectly there is evidence of a change in soil PH, there is a zone where fossils are lacking around the boundary, Many propose this is due to a drastic change in the soils around at the time. soils that would have preserved fossils suddenly shifted in PH and PH has a big effect in fossil preservation. – John Aug 13 '20 at 14:00
• @John Thanks for the comment. I imagine it is not simple to distinguish however between pH changes due to drastic alteration of the biosphere versus from deposition of massive amounts of sulfuric acid. – Buck Thorn Aug 14 '20 at 9:30

so the release is $$\approx 1000\times$$ today's annual sulfur cycle.
• I'm sort of thinking out loud here. I see that the oceans are 3% sulfate so the increase in sulfur concentration is negligible in the oceans (1.332 billion cubic kilometers ). (Cubic kilometer $\approx$ gigatonne.) – Keith McClary Feb 27 '19 at 17:58