Effects of uranium concentration on microbial community structure and functional potential

Area of Science:

• Environmental Science
• Microbiology
• Ecotoxicology

Background:

• Ranger uranium mine in Australia's Northern Territory is near Kakadu National Park, requiring site rehabilitation post-closure in 2026.
• Understanding uranium's impact on microbial ecosystems is vital for assessing ecosystem services and rehabilitation success.

Purpose of the Study:

• To investigate the effects of varying uranium concentrations on microbial community structure and function.
• To identify critical uranium concentration thresholds impacting microbial ecosystem services.

Main Methods:

• In situ deployment of uranium-spiked sediments across a concentration gradient (0–4000 mg U kg⁻¹).
• Utilisation of amplicon and shotgun metagenomic next-generation sequencing to characterise microbial communities.
• Integration of field survey and laboratory manipulative study advantages.

Main Results:

• Significant shifts in microbial taxonomic and functional community assembly were detected at uranium concentrations of 1500 mg U kg⁻¹ and higher.
• Increased relative abundance of genes associated with methanogenic consortia and processes at ≥1500 mg U kg⁻¹.
• Notable alterations in the relative abundance of genes involved in nitrogen cycling.

Conclusions:

• Uranium concentrations ≥1500 mg kg⁻¹ significantly alter microbial community structure and function.
• Changes in microbial genes related to carbon and nitrogen cycling indicate potential disruption of ecosystem services.
• Findings provide critical data for the rehabilitation of uranium-impacted sites adjacent to sensitive environments like Kakadu National Park.