Abstract
Highlight
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- Hydrogen fluoride inhibits microbial activity in soil even after natural attenuation.
- Plants are harmed by reactive oxygen species produced by pH-neutralized soil.
- Plants overexpress ABR1 and DREB1A in response to acid stress.
- Plants generate reactive oxygen species detoxifiers after hydrogen fluoride exposure.
- pH-neutralized soil can cause phenotypic defects and reduce the yield of crops.
Accidental chemical leaks and illegal chemical discharges are a global environmental issue. In 2012, a hydrogen fluoride leak in Gumi, South Korea, killed several people and contaminated the environment. This leak also led to a significant decline in crop yield, even after the soil concentration of hydrogen fluoride decreased to below the standard level following natural attenuation. To determine the cause of this decreased plant productivity, we designed direct and indirect exposure tests by evaluating the metabolome, transcriptome, and phenome of the plants. In an indirect exposure test, soil metabolomics revealed downregulation of metabolites in vitamin B6, lipopolysaccharide, osmolyte, and exopolysaccharide metabolism. Next-generation sequencing of the plants showed that ABR1 and DREB1A were overexpressed in response to stress. Plant metabolomics demonstrated upregulation of folate biosynthesis and nicotinate and nicotinamide metabolism associated with detoxification of reactive oxygen species. These results demonstrate impaired metabolism of soil microbes and plants even after natural attenuation of hydrogen fluoride in soil. The novel chemical exposure testing used in this study can be applied to identify hidden damage to organisms after natural attenuation of chemicals in soil, as well as biomarkers for explaining the decline in yield of plants grown in soil near pollutant-emitting industrial facilities.
Graphical Abstract
Excerpt:
… Hydrogen fluoride (HF) is a colorless gas or liquid that is frequently used to remove impurities from semiconductors and other electronic products. It is also among the most dangerous inorganic acids, as accidental release of HF causes very serious environmental problems not only through underground leakage of liquid chemicals spreading along
underground plumes, but also by leakage of aerosols propagating through the air current. Additionally, HF release can harm human health by damaging the eyes, skin, liver, kidneys, and respiratory organs (Lim and Lee, 2012). For example, a petroleum plant in Texas released 18 tons of HF in 1987, which led to eye irritation and respiratory problems in hundreds of people, as well as massive destruction of vegetation near residential areas (HSE, 1987). In September 2012, another massive HF aerosol leak (8 tons) occurred at a facility in Gumi, South Korea. The consequent ecological damage was massive because the ground surface was directly polluted by HF aerosols, injuring more than 200 ha of neighboring crops and livestock (Yang et al., 2017). A damage investigation was conducted to assess the adverse effects of acute and chronic exposure by monitoring the concentration of HF in soils and damage to plants and livestock (Jung, 2017). However, farmers continued to report declining crop yields, even though the concentration of HF in the soil fell to below the standard level. They insisted that the reduction in crop yield was a consequence of HF leakage. However, no scientific verification tool was available to explain the hidden damage decreasing the crop yield because a low HF concentration was expected to have little or no impact on soil and plants….
Environmental Implication
Hydrogen fluoride is widely used in industrial facilities to clean impurities on semiconductors, leading to accidental HF leaks worldwide in many countries. Exposure to HF leaks can cause massive soil ecosystem devastation, even after the soil appears to have recovered from the HF leak. Crop yields are still decreased after the HF level returns to its basal level through natural attenuation. The approach used in this study revealed this decreased yield was caused by reductions in the microbial activity and water-holding capacity of soil. Our method can be utilized to improve environmental forensics.
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