Deciphering the significant role of biological ice nucleators in
precipitation at the organic molecular level
Abstract
Biological particles, as a fraction of organic particles, potentially
play a crucial role in ice nucleation processes. However, the
contributions and relationships of biological components and organic
matter (OM) to atmospheric ice nucleation are still largely unexplored.
Here, droplet freezing assays, high-throughput sequencing technology and
ultrahigh-resolution mass spectrometry were performed to detect the
INPs, microorganisms and OM molecules in precipitation collected at the
summit of Mt. Lu, China, respectively. Results revealed a predominant
biological composition (71.7% and 93.2%) of total and nanoscale INPs
(< 0.22 μm) at temperatures above −15°C. Specifically,
bacterial INPs accounted for 36.1% of the biological INPs at
temperatures above −15°C. A notable correlation between
sulfur-containing compounds, mainly proteinaceous and lignin-like
substances, and INPs was uncovered, with a co-occurrence network linking
these compounds to Gram-positive bacteria and Agaricomycetes. This study
underscored the possible significance of sulfur-containing compounds in
biological INP efficiency, which could further help shed light on the
ice nucleation mechanisms and potential sources of biological INPs.