Pyrethroid residues on tropical soil of an Indonesian tea plantation: analytical method development, monitoring, and risk assessment

Abstract

Despite their massive application in tea plantation, synthetic pyrethroids had never been detected in tropical soils of tea plantation thus their risk has never been assessed. This research reported the detection of synthetic pyrethroids in tea plantation and assessed their aquatic ecotoxicological risk. A simplified analytical method based on the application of a miniaturized sample, solvent, and efficient ultra-sonic assisted extraction was developed for the determination of pyrethroids in the soil. The method was validated with the result of all parameters (recovery, % relative standard deviations, linearity, limit of detection (LoD), and matrix effect) met the acceptance limits suggested by European Commission guideline, thus deemed acceptable for the assessment of pyrethroids in tropical soil of tea plantation during the wet and dry season. Of the five synthetic pyrethroids, only permethrin was detected in both wet and dry seasons (< LoD – 0.36 μg g− 1), whereas deltamethrin was detected only in wet season (< LoD – 0.12 μg g− 1). Scanning electron microscopy with energy-dispersive X-ray spectrometry and X-ray diffraction revealed that the soil constituted by various soil minerals made permethrin more likely to persist than deltamethrin. Aquatic ecotoxicological risk assessment was performed on the basis of comparison between the maximum equilibrium concentration expected in water (ECEWmax) value and lethal concentration (LC50) of pyrethroids exposure for aquatic species (algae, crustacean, and fish) inhabiting the Upper Citarum River. The ECEWmax value for the present condition was lower than LC50 for all examined species, indicating that the high-level contamination in the future should have posed a high risk for all aquatic species based on their LC50.