Dinotefuran, a third-generation neonicotinoid insecticide, is widely used in agriculture production due to its excellent insecticidal efficacy. Considering its persistence and high toxicity in soil, it is essential to evaluate its low-dose toxic effects on non-target soil organisms such as the springtail (Folsomia candida). The results revealed that the 7-day half lethal concentration (7d-LC50) of dinotefuran contact toxicity to springtails was 0.029 mu g cm(-2). Its chronic toxicity in 4 soil types was ranked as: red soil (0.021 mg kg(-1)) > fluvo-aquic soil (0.040 mg kg(-1)) > artificial soil (0.049 mg kg(-1)) > black soil (0.085 mg kg(-1)). Soil organic matter (SOC), pH, and total nitrogen (TN) were identified as critical factors affecting dinotefuran toxicity. Biochemical assay results showed that environmental concentrations (0.2-1.6 mg kg(-1)) of dinotefuran induced oxidative stress and oxidative damage in springtails. Oxidative stress-related enzymes (including superoxide dismutase (SOD) and catalase (CAT)) and detoxification enzymes were subjected to initial activation at low dinotefuran concentrations, inhibition and re-activation at high concentration. Target enzyme acetylcholinesterase (AChE), malondialdehyde (MDA) content, and total protein content were inhibited with prolonged exposure time and increasing concentrations of dinotefuran. Molecular docking analysis showed that dinotefuran bound to the active sites of related enzymes, thus disrupting their structure and functions, eventually resulting in damages to physiological functions of springtails. In summary, this study deciphers the dinotefuran toxicological mechanism on soil springtails at environmental concentrations. Our findings lay theoretical basis for further assessing its pollution risk and managing its application.

The ecotoxic effect of Zn species arising from the weathering of the marmatite-like sphalerite ((Fe, Zn)S) in Allium cepa systems was herein evaluated in calcareous soils and connected with its sulfide oxidation mechanism to determine the chemical speciation responsible of this outcome. Mineralogical analyses (X-ray diffraction patterns, Raman spectroscopy, scanning electron microscopy and atomic force microscopy), chemical study of leachates (total Fe, Zn, Cd, oxidation-reduction potential, pH, sulfates and total alkalinity) and electrochemical assessments (chronoamperometry, chronopotentiometry, cyclic voltammetry, and electrochemical impedance spectroscopy) were carried out using (Fe, Zn)S samples to elucidate interfacial mechanisms simulating calcareous soil conditions. Results indicate the formation of polysulfides (S-n(2-)), elemental sulfur (S-0), siderite (FeCO3)-like, hematite (Fe2O3)-like with sorbed CO32- species, gunningite (ZnSO4H2O)-like phase and smithsonite (ZnCO3)-like compounds in altered surface under calcareous conditions. However, the generation of gunningite (ZnSO4H2O)-like phase was predominant bulk-solution system. Quantification of damage rates ranges from 75 to 90% of bulb cells under non-carbonated conditions after 15-30 days, while 50-75% of damage level is determined under neutral-alkaline carbonated conditions. Damage ratios are 70.08 and 30.26 at the highest level, respectively. These findings revealed lower ecotoxic damage due to ZnCO3-like precipitation, indicating the effect of carbonates on Zn compounds during vegetable up-taking (exposure). Other environmental suggestions of the (Fe, Zn)S weathering and ecotoxic effects under calcareous soil conditions are discussed.