Along with the development of nanotechnology, nanomaterials have been gradually applied to agriculture in recent years, such as Cu(OH)2-nanorods-based nanopesticide, an antibacterial agrochemical with a high efficacy. Nevertheless, knowledge about physical stability of Cu(OH)2nanopesticide in soil solutions is currently scarce, restricting comprehensive understanding of the fate and risk of Cu(OH)2nanopesticide in the soil environment. Herein we investigated aggregation, sedimentation and dissolution of Cu(OH)2nanopesticide in soil solutions extracted from three different soil samples, wherein commercial Cu(OH)2nanopesticide formulation (NPF), as well as its active ingredient (AI) and laboratory-prepared Cu(OH)2nanorods (NR) with similar morphology as AI, were used as model Cu(OH)2nanopesticides. We found that NPF compared to AI showed less extents of aggregation in ultrapure water due to the presence of dispersing agent in NPF. Yet, moderated aggregation and sedimentation were observed for Cu(OH)2nanopesticide irrespective of NPF, AI or NR when soil solutions were used instead of ultrapure water. The sedimentation rate constants of AI and NPF were 0.023 min−1and 0.010 min−1in the ultrapure water, whereas the rate constants of 0.003–0.021 min−1and 0.002–0.007 min−1were observed for AI and NPF in soil solutions, respectively. Besides aggregation and sedimentation, dissolution of Cu(OH)2nanopesticide in soil solutions was highly dependent on soil type, wherein pH and organic matter played important roles in dissolution. Although the final concentrations of dissolved copper (1.08–1.37 mg/L) were comparable among different soil solutions incubating 48 mg/L of AI, NPF or NR for 96 h, a gradual increase followed by an equilibrium was only observed in the soil solution from acidic soil (pH 5.16) with the low content of organic matter (1.20 g/kg). This work would shed light on the fate of Cu(OH)2nanopesticide in the soil environment, which is necessary for risk assessment of the nanomaterials-based agrochemical.Keywords:soil solutions;aggregation;sedimentation;Cu(OH)2nanopesticide;dissolution
Enguang Nie,Haiyan Wang,Yan Chen,Yuhui Lu,Kashif Akhtar,Muhammad Riaz,Sufen Zhang,Zhiyang Yu,Qingfu Ye
Triclosan is a widely used biocide against microorganisms and is ubiquitously distributed in the environment. Triclosan can be accumulated into plants from soil and hydroponic media. However, little information is currently available on the comparative fate of triclosan in plants under soil and hydroponics cultivation conditions and factors governing uptake. Therefore, this study was designed to comparatively elucidate the uptake mechanism of 14 C-triclosan in youdonger ( Brassica campestris subsp. Chinensis var. communis ) grown under different soils and hydroponics and clarify dominant uptake factors. Results showed that 77.2% of 14 C were accumulated in youdonger grown in a hydroponic system, while only 1.24%–2.33% were accumulated in the two soil-planting systems. In addition, the bioconcentration factor (BCF) of 14 C-triclosan in soil-plant systems was approximately 400-fold smaller than that in the hydroponics. In the soil-planting system, a strong linear correlation was found between concentrations of triclosan in soil pore water and youdonger plant (R 2 > 0.85, p < 0.01) at different incubation times. Therefore, triclosan in pore water might be a good indicator to estimate its accumulation in plants and is significantly affected by soil pH, clay, and organic matter contents. The estimated average dietary intakes of triclosan for youdonger grown in hydroponic and soil-planting systems were estimated to be 1.31 ng day −1 kg −1 and 0.05–0.12 ng day −1 kg −1 , respectively, much lower than the acceptable dietary intakes of triclosan (83 μg day −1 kg −1 ), indicating no significant human health risks from youdonger consumption. This study provided insights into uptake routes of triclosan into youdonger plants from both soil and hydroponic systems, bioavailability of triclosan in different soils, and further assessment of human exposure to triclosan from youdonger.
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