Sorption-desorption and biodegradation of sulfometuron-methyl and its effects on the bacterial communities in Amazonian soils amended with aged biochar

• Published in: Ecotoxicology and environmental safety 2021-01, Vol.207, p.111222, Article 111222
• Main Authors: Obregón Alvarez, Dasiel, Mendes, Kassio Ferreira, Tosi, Micaela, Fonseca de Souza, Leandro, Campos Cedano, Johnny Carlos, de Souza Falcão, Newton Paulo, Dunfield, Kari, Tsai, Siu Mui, Tornisielo, Valdemar Luiz
• Format: Article
• Language: English
• Subjects: Adsorption; Bacteria - metabolism; Bacterial community; Bioavailability; Biodegradation, Environmental; Biodiversity; Biological Availability; Brazil; Carbon black; Charcoal; Herbicide; Herbicides - analysis; RNA, Ribosomal, 16S - metabolism; Soil; Soil Pollutants - analysis; Sulfonylurea Compounds - analysis; Tropical soil
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2020.111222

Sulfometuron-methyl is a broad-spectrum herbicide, used throughout Brazil; however, its environmental impacts in biochar (BC) amended soils is not fully understood. Biochar is known to enhance soil quality but can also have undesired effects such as altering the bioavailability and behavior of herbicides. Microbial communities can degrade herbicides such as sulfometuron-methyl in soils; however, they are known to be affected by BC. Therefore, it is important to understand the tripartite interaction between these factors. This research aimed to evaluate the sorption-desorption and biodegradation of sulfometuron-methyl in Amazonian soils amended with BC, and to assess the effects of the interactions between BC and sulfometuron-methyl on soil bacterial communities. Soil samples were collected from field plots amended with BC at three doses (0, 40 and 80 t ha−1) applied ten years ago. The herbicide sorption and desorption were evaluated using a batch equilibrium method. Mineralization and biodegradation studies were conducted in microcosms incubated with 14C-sulfometuron-methyl for 80 days. Systematic soil sampling, followed by DNA extraction, quantification (qPCR) and 16S rRNA amplicon sequencing were performed. The presence of BC increased the sorption of the herbicide to the soil by 11% (BC40) and 16% (BC80) compared to unamended soil. The presence of BC also affected the degradation of 14C-sulfometuron-methyl, reducing the mineralization rate and increasing the degradation half-life times (DT50) from 36.67 days in unamended soil to 52.11 and 55.45 days in BC40 and BC80 soils, respectively. The herbicide application altered the bacterial communities, affecting abundance and richness, and changing the taxonomic diversity (i.e., some taxa were promoted and other inhibited). A tripartite interaction was found between BC, the herbicide and soil bacterial communities, suggesting that it is important to consider the environmental impact of soil applied herbicides in biochar amended soils. [Display omitted] •The effects of sulfometuron-methyl on soil bacteria were explored in biochar-amended soils.•Biochar addition increased herbicide sorption in soils by more than 10%.•Biochar affected herbicide degradation, increasing half-life from 36 to more than 50 days.•The herbicide reduced bacterial richness, especially in the presence of biochar.•Different taxa were promoted/inhibited by the herbicide, depending on the biochar levels.