Arsenic release dynamics in Punjab's agricultural soils: the role of background species using fractional factorial design

Arsenic contamination has become an important environmental issue in India, particularly in Punjab, where intensive agriculture and groundwater dependence have exacerbated the problem. However, limited attention has been paid to the effects of arsenic release from soils and the role of background species in this process. This work investigates arsenic (As) release from agricultural soils at different depths in Theh Kalan village, Tarn Taran district, Punjab, and examines the effects of background species using batch experiments. Arsenic release followed the order: subsoil > bottom soil > topsoil, with higher release in the absence of background species. The impact of six ionic species (SiO32−, PO43−, HCO3−, SO42−, Ca2+, and Cl−) was assessed using a 26–2 fractional factorial design (FFD). In single-ion systems, PO43−, SiO32−, and HCO3− increased release, SO42− and Cl− had slight effects, while Ca2+ reduced release. In multi-ion systems, PO43− > SiO32− > HCO3− > SO42− enhanced release, whereas Ca2+ > Cl− limited it. Significant interactions of SiO32− × PO43− and SiO32− × HCO3− were observed. Model adequacy was evaluated using ANOVA and residual analysis. These findings highlight the strong influence of background species on arsenic release from soils and their implications for groundwater contamination.