Degradation, adsorption and leaching of phenazine-1-carboxamide in agricultural soils

Jiang Ou; Hui Li; Xiaoming Ou; Zhifu Yang; Mengxian Chen; Kailin Liu; Yuting Teng; Baoshan Xing

doi:10.1016/j.ecoenv.2020.111374

Degradation, adsorption and leaching of phenazine-1-carboxamide in agricultural soils

Ecotoxicol Environ Saf. 2020 Dec 1:205:111374. doi: 10.1016/j.ecoenv.2020.111374. Epub 2020 Sep 22.

Authors

Jiang Ou¹, Hui Li², Xiaoming Ou³, Zhifu Yang³, Mengxian Chen³, Kailin Liu⁴, Yuting Teng⁵, Baoshan Xing²

Affiliations

¹ College of Plant Protection, Hunan Agricultural University, Changsha, 410128, China; National Engineering Research Center for Agrochemicals, And Hunan J&F Test Co.Ltd, Hunan Research Institute of Chemical Industry, Changsha, 410014, China.
² Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, 01003, United States.
³ National Engineering Research Center for Agrochemicals, And Hunan J&F Test Co.Ltd, Hunan Research Institute of Chemical Industry, Changsha, 410014, China.
⁴ College of Plant Protection, Hunan Agricultural University, Changsha, 410128, China; Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, 01003, United States. Electronic address: kailin@hunau.net.
⁵ College of Plant Protection, Hunan Agricultural University, Changsha, 410128, China.

PMID: 32977284
DOI: 10.1016/j.ecoenv.2020.111374

Abstract

Phenazines, a large group of nitrogen-containing heterocycles with promising bioactivities, can be widely used as medicines and pesticides. But phenazines also generate toxicity risks due to their non-selective DNA binding. The environmental fate of phenazines in soils is the key to assess their risks; however, hitherto, there have been very few related studies. Therefore in the present study, the degradation, adsorption and leaching behaviors of a typical natural phenazine-phenazine-1-carboxamide (PCN) in agricultural soils from three representative places in China with different physicochemical properties were, for the first time, systematically studied in laboratory simulation experiments. Our results indicated that the degradation of PCN in all the tested soils followed the first order kinetics, with half-lives ranging from 14.4 to 57.8 d under different conditions. Soil anaerobic microorganisms, organic matter content and pH conditions are important factors that regulating PCN degradation. The adsorption data of PCN were found to be well fitted using the Freundlich model, with the r² values above 0.978. Freundlich adsorption coefficient K_f of PCN ranged from 5.75 to 12.8 [(mg/kg)/(mg/L)^1/n] in soils. The retention factor R_f values ranged from 0.0833 to 0.354, which means that the mobility of PCN in the three types of soil is between immobile to moderately mobile. Our results demonstrate that PCN is easily degraded, has high adsorption affinity and low mobility in high organic matter content and clay soils, thus resulting in lower risks of contamination to groundwater systems. In contrast, it degraded slowly, has low adsorption affinity and moderately mobile in soils with low organic matter and clay content, therefore it has higher polluting potential to groundwater systems. Overall, these findings provide useful insights into the future evaluation of environmental as well as health risks of PCN.

Keywords: Adsorption; Agricultural soils; Degradation; Leaching; Phenazine-1-carboxamide.

MeSH terms

Adsorption
Agriculture
China
Clay
Groundwater
Kinetics
Pesticides
Phenazines / analysis*
Soil / chemistry
Soil Pollutants / analysis*

Substances

Pesticides
Phenazines
Soil
Soil Pollutants
phenazine-1-carboxamide
Clay