Hexachlorobutadiene pollution affected soil ammonia oxidation processes through affecting ammonia oxidizing...

Area of Science:

• Environmental Science
• Microbiology
• Soil Science

Background:

• Hexachlorobutadiene (HCBD) is a persistent organic pollutant (POP) posing risks to ecosystems and human health.
• Soil ammonia oxidation is a critical step in nitrogen cycling, mediated by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA).

Purpose of the Study:

• To investigate the effects of HCBD on the soil ammonia oxidation process.
• To assess the impact of HCBD on the abundance and diversity of AOB and AOA.

Main Methods:

• A 30-day microcosmic controlled experiment was conducted using HCBD-treated soil.
• Quantitative PCR was used to measure the abundance of amoA genes in AOB and AOA.
• Analysis of microbial community diversity and correlation analysis with environmental factors (e.g., HCBD, NH4+-N, NO3--N, pH) were performed.

Main Results:

• Soil ammonia oxidation was inhibited by HCBD starting on day 6.
• HCBD significantly reduced the abundance of AOB and AOA, with AOA showing greater sensitivity and significant reductions from day 6 to day 30.
• HCBD significantly affected AOA diversity more than AOB diversity. Specific AOA taxa showed strong negative correlations with HCBD, while a dominant AOB species showed a positive correlation.
• Redundancy analysis (RDA) indicated HCBD and NH4+-N were key factors influencing AOA communities, while NH4+-N and pH primarily affected AOB communities.

Conclusions:

• HCBD contamination has a pronounced impact on soil ammonia oxidation by affecting both AOB and AOA, particularly AOA.
• The findings highlight the ecological risks of HCBD pollution on vital soil microbial processes and nitrogen cycling.