Fluoride contamination in plum and peach orchards and its impact on earthworm growth and reproduction

Abstract

This study investigated fluoride contamination in plum (Prunus domestica) and peach (Prunus persica) orchards near brick kilns in Urmar, Peshawar, Pakistan, and its impact on the growth and reproduction of Eisenia fetida spp. of earthworms. Soil and leaf samples (n = 24 per site, 12 per orchard) were collected from a test site within 500 m of brick kilns and a control site 30 km away. Fluoride levels, analyzed using ion-selective electrodes, were significantly higher (p < 0.05) at the test site, with soil concentrations of 13.5 µg/g (peach) and 13.0 µg/g (plum) compared to 2.57 µg/g and 2.50 µg/g at the control site, and leaf concentrations of 68.57 μg/g (peach) and 31.0 μg/g (plum) versus 5.23 µg/g and 4.86 µg/g at the control site. Earthworms exposed to contaminated, non-contaminated, and control treatments showed significant reductions in biomass (1.37–2.88 g), length (10.18–13.37 mm), and cocoon production (6.25–30.25) in fluoride-contaminated treatments compared to controls (p < 0.05, ANOVA with Tukey’s HSD). Elevated fluoride levels, attributed to brick kiln emissions, impaired earthworm growth and reproduction, threatening soil health. Regular monitoring and mitigation strategies are recommended to manage fluoride pollution.