Behavior and fate of fungicide chlorothalonil in urban landscape soils and associated environmental concern

This novel study investigated the behavior and fate of chlorothalonil in terms of kinetics, sorption-desorption and leaching potential in urban landscape soils using batch experiments. The pseudo-second-order model well described the sorption kinetics of chlorothalonil in urban soils. Consequently, chlorothalonil was partitioned into heterogeneous surfaces of soil following the Freundlich isotherm model. According to PCA, soil organic matter (OM), silt, clay, and oxides of Al and Fe exhibited a significant positive correlation (P < 0.05) with chlorothalonil K-d (P < 0.05), while sand content and soil pH showed a negative correlation at P < 0.05. In soils, decreased sorption of chlorothalonil was also due to the presence of undecomposed or partly decomposed OM, whereas increased sorption could be attributed to the combined effect of OM with C = O and C-H groups, silt, clay, Al and Fe oxides and hydrophobicity of the fungicide. Also, HI, GUS, LIX and K-d of four among nine urban soils indicated that chlorothalonil has a great potential for leaching into the groundwater from the soil surface, posing an unintended threat to non-target biota and food safety. Therefore, utmost care must be taken while applying chlorothalonil in urban landscapes, particularly on impervious surfaces, to minimize the impact on the ecosystem.

Automated summary

The study found that the sorption behavior of chlorothalonil in urban soils is influenced by soil properties, with soil organic matter, silt, clay, and oxides of aluminum and iron showing a significant positive correlation with chlorothalonil's K-d value. In urban soils, the decreased sorption of chlorothalonil is mainly attributed to the presence of organic matter, while the increased sorption may be related to factors such as organic matter, clay, aluminum and iron oxides, as well as the fungicide's hydrophobicity.