A new framework integrating crop growth–level IV fugacity model and eco-indicator sensitivity to assess neonicotinoid fate and ecological risk in tropical rice–vegetable rotations

Abstract

Tropical rice–vegetable rotations face escalating pesticide management challenges due to alternating wet–dry conditions, high neonicotinoid (NEO) input, and complex multimedia transport, yet existing models overlook dynamic crop growth and rotation-specific risks. To address this, we constructed an innovative pesticide assessment framework by combining continuous crop growth curve–level IV fugacity model (CGC-L4F) and eco-indicator sensitivity distribution (Eco-SD) to predict the fate and ecological risks of NEOs in multimedia of tropical rice–vegetable rotation systems. Applying the framework to imidacloprid, acetamiprid, and their shared transformation product 6-chloronicotinic acid (6-CNA) in four field-applied rice–vegetable rotation systems revealed that NEOs and 6-CNA concentrations in multimedia decreased by 1.13–5.67 times from vegetable to rice growth period, primarily attributed to NEOs input, crop rotation, and plant growth. Crop rotation pattern and crop volume exacerbated NEO heterogeneity of distribution and transport within and between multimedia, causing easy accumulation in water and plants from soil. The CGC-L4F model consistently simulated temporal variations with strong statistical fit (R² > 0.7) and acceptable deviation (±1 log unit). The Eco-SD approach, incorporating ecosystem service providers, successfully identified media-specific and seasonally differentiated risk patterns. This framework, focusing on dynamic crop growth and ecosystem services, is the first to quantify NEOs’ temporal fate and risks in rotation systems, demonstrating that integrated modeling offers robust predictive capacity despite inherent uncertainties.