Influence of soluble copper on the electrokinetic properties and transport of copper oxychloride-based fungicide particles

Effect of NaNO3, NH4Cl and urea on the fate and transformation of various typical microplastics in porous media

Understanding the transport behaviors of microplastics (MPs) in porous media is crucial in controlling MPs pollution. Given nitrogen is one of the most important nutrients in soil and groundwater systems, unclearness of the transport behaviors of microplastics (MPs) under various nitrogen conditions may inhibit the acknowledgment of MPs fate. For this reason, this study innovatively investigates the transport characteristics of four kinds of typical MPs (PVC MPs, PMMA MPs, PET MPs, and PP MPs) under various NaNO3, NH4Cl and urea conditions via column experiments numerical models. The FTIR and XPS analysis were conducted to excavate the transform of MPs. The MPs mobility was generally reduced with the increasing nitrogen concentrations. The polarity and density properties of different MPs played combined roles in transport under similar conditions. Compared to NO3-, NH4+ may neutralize the negative charge of MPs and then restrain their transport in porous media. Urea may coat the surface of MPs and promote the mobility, however, increasing concentrations of urea may result in the interattraction between MPs and porous media via hydrogen-bond and π-π interaction. PET MPs and PP MPs showed barely transform during transport under the tested conditions. Particularly, the chlorines on PVC MPs could react with the amide on urea and produce amidogen, which may improve PVC MPs transport. The N-H and C-N bond also generated on PMMA MPs in presence of urea also may enhance the mobility.

Fungicide application can intensify clay aggregation and exacerbate copper accumulation in citrus soils

Fungicide application for controlling fungal diseases can increase copper (Cu) accumulation in soil. More urgently, Cu released from fungicides can associate with soil clay and favour the mutual aggregation of Cu and soil clay, thereby potentially intensifying the accumulation of Cu. We investigated the effects of Cu salt and six common Cu-based fungicides on colloidal dynamics of a clay fraction from citrus cultivated soil. Batch experiments were carried out to provide the loading capacity of the clay fraction for Cu. The colloidal dynamic experiments were performed over a pH range from 3 to 8 following a test tube method, while surface charge, the key electrochemical factor of the solid-liquid interface, was quantified by a particle charge detector. It was found that all the studied fungicides, via releasing Cu²⁺, acted to effectively favour clay aggregation. The dissolved organic matter obtained from the dissolution of polymers in fungicides can theoretically stimulate clay dispersion. However, their effects were obscured due to the overwhelming effect of Cu²⁺. Therefore, Cu²⁺ appears as the most active agent in the fungicides that intensifies clay aggregation. These findings imply that the intensive application of fungicides for plant protection purposes can inadvertently reduce clay mobility, favour the co-aggregation of clay and fungicides, and hence potentially exacerbate the contamination of the citrus soil.

Nanotechnology in the Treatment of Diabetic Complications: A Comprehensive Narrative Review

In today's society, the prevention and treatment of diabetes mellitus and its subsequent complications have brought trouble to human beings. Complications caused by diabetes bring not only physical and mental pain to patients but also a heavy economic burden to families. And once diabetic complications occur, they are often irreversible and very difficult. At present, some studies suggest that nanotechnology can treat some diabetic complications. This paper reviews the application of nanotechnology in the repair of diabetic segmental bone injury, the healing of diabetic skin ulcers, the therapeutic effect, and improvement strategies and deficiencies of nanotechnology in diabetic complications.

Effects of past copper contamination and soil structure on copper leaching from soil

Copper contamination affects biological, chemical, and physical soil properties and associated ecological functions. Changes in soil pore organization as a result of Cu contamination can dramatically affect flow and contaminant transport in polluted soils. This study assessed the influence of soil structure on the movement of water and Cu in a long-term polluted soil. Undisturbed soil cores collected along a Cu gradient (from about 20 to about 3800 mg Cu kg soil) were scanned using X-ray computed tomography (CT). Leaching experiments were performed to analyze tracer transport, colloid leaching, and dissolved organic carbon (DOC) and Cu losses. The 5% arrival time () and apparent dispersivity (λ) for tracer breakthrough were calculated by fitting the experimental data to a nonparametric, double-lognormal probability density function. Soil bulk density, which did not follow the Cu gradient, was the main driver of preferential flow, while macroporosity determined by X-ray CT (for pores >180 μm) proved the best predictor of solute transport. Higher preferential flow due to the presence of well-aligned pores and small cracks controlled water movement in compacted soil. Transport of Cu was rapid during the first flush (≈1 pore volume) in association with the movement of colloid particles, followed by slower transport in association with the movement of DOC in the soil solution. The relative amount of Cu released was strongly correlated with macroporosity as determined by X-ray CT, indicating the promising potential of this visualization technique for predicting contaminant transport through soil.

Modeling the influence of raindrop size on the wash-off losses of copper-based fungicides sprayed on potato (Solanum tuberosum L.) leaves

Modeling the pesticide wash-off by raindrops is important for predicting pesticide losses and the subsequent transport of pesticides to soil and in soil run-off. Three foliar-applied copper-based fungicide formulations, specifically the Bordeaux mixture (BM), copper oxychloride (CO), and a mixture of copper oxychloride and propylene glycol (CO-PG), were tested on potato (Solanum tuberosum L.) leaves using a laboratory raindrop simulator. The losses in the wash-off were quantified as both copper in-solution loss and copper as particles detached by the raindrops. The efficiency of the raindrop impact on the wash-off was modeled using a stochastic model based on the pesticide release by raindrops. In addition, the influence of the raindrop size, drop falling height, and fungicide dose was analyzed using a full factorial experimental design. The average losses per dose after 14 mm of dripped water for a crop with a leaf area index equal to 1 were 0.08 kg Cu ha(-1) (BM), 0.3 kg Cu ha(-1) (CO) and 0.47 kg Cu ha(-1) (CO-PG). The stochastic model was able to simulate the time course of the wash-off losses and to estimate the losses of both Cu in solution and as particles by the raindrop impacts. For the Cu-oxychloride fungicides, the majority of the Cu was lost as particles that detached from the potato leaves. The percentage of Cu lost increased with the decreasing raindrop size in the three fungicides for the same amount of dripped water. This result suggested that the impact energy is not a limiting factor in the particle detachment rate of high doses. The dosage of the fungicide was the most influential factor in the losses of Cu for the three formulations studied. The results allowed us to quantify the factors that should be considered when estimating the losses by the wash-off of copper-based fungicides and the inputs of copper to the soil by raindrop wash-off.