An anomalous warm weather event in the Antarctic McMurdo Dry Valleys on 18 March 2022 created an opportunity to characterize soil biota communities most sensitive to freeze-thaw stress. This event caused unseasonal melt within Taylor Valley, activating stream water and microbial mats around Canada Stream. Liquid water availability in this polar desert is a driver of soil biota distribution and activity. Because climate change impacts hydrological regimes, we aimed to determine the effect on soil communities. We sampled soils identified from this event that experienced thaw, nearby hyper-arid areas, and wetted areas that did not experience thaw to compare soil bacterial and invertebrate communities. Areas that exhibited evidence of freeze-thaw supported the highest live and dead nematode counts and were composed of soil taxa from hyper-arid landscapes and wetted areas. They received water inputs from snowpacks, hyporheic water, or glacial melt, contributing to community differences associated with organic matter and salinity gradients. Inundated soils had higher organic matter and lower conductivity (p < .02) and hosted the most diverse microbial and invertebrate communities on average. Our findings suggest that as liquid water becomes more available under predicted climate change, soil communities adapted to the hyper-arid landscape will shift toward diverse, wetted soil communities.

Within an identical soil environment, various pesticides may be commonly identified, but their collective toxicological traits have not been thoroughly investigated. This research sought to elucidate the potential consequences of concurrent exposure to multiple pesticides on soil organisms, with a specific emphasis on examining alterations in transcript and enzyme levels induced by the co-presence of acetamiprid (ACE) and tetraconazole (TET) in earthworms (Eisenia fetida). The results indicated that the joint presence of ACE and TET exhibited an acute synergistic impact on the organisms. Notably, there was a significant elevation in the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), coupled with a substantial suppression of caspase-9 and caspase-3 contents observed in the majority of both individual and combined groups. These findings suggested the occurrence of oxidative stress and cell death. Furthermore, the study revealed a substantial up-regulation of three genes (gst, sod, and crt) and down-regulation of one gene (mt) after exposure to individual pesticides and their mixtures. This pointed towards dysregulation of detoxification processes and oxidative damage. Collectively, the study underscored that the widespread application of these two pesticides might pose potential ecotoxicological risks to the soil ecosystem. In essence, these discoveries enriched our insights into the potential hazards linked to the simultaneous use of multiple pesticides in real-world settings. They underscored the significance of taking into account both synergistic effects and employing judicious pesticide management strategies to alleviate ecological impacts.