Leaching of allelochemicals in soil is one of the fundamental processes that determines allelopathic activities but is often overlooked. In the present study, the vertical leaching of seven putative allelochemicals as well as one pesticide and one herbicide was investigated using polyvinyl chloride columns combined with a bioassay approach. The results indicated that the leachability of pretilachlor and imidacloprid were the best (Lf > 0.8), followed by vanillin and coumarin (Lf > 0.6). The leachability of daidzein, menthol, and m-tyrosine were medium (0.3 < Lf < 0.6). The lowest leachability has been observed on p-coumaric and p-hydroxybenzoic acids (Lf < 0.3). The chemicals were classified into three clusters according to the phospholipid fatty acid profile (i.e., vanillin in one cluster, coumarin and menthol in the second cluster, and the rest in the third cluster). Bioactivities of the chemicals changed dramatically. Germination of lettuce seeds was suppressed by imidacloprid and pretilachlor, and the suppression was concentration-dependent. The bioactivity of most of the allelochemicals were progressively decreased with the downward movement of chemicals. The results indicated that leaching mediated the microbial communities and the interactions of chemical–microorganism and modified the bioavailability of allelochemicals in soil.
Xiaoxu Ma,Mingxin Liu,Yanzhen Chen,Qiliang Huang,Chong Cao
Dinotefuran (DIN) contaminates groundwater and is toxic to bees, so designing a novel pesticide loading system for dinotefuran is of great significance. In this paper, dinotefuran was loaded into TpBDMe COF with a mesoporous hollow structure, and the TpBDMe COF loaded with dinotefuran exhibited initial burst and subsequent sustained release behavior. The results showed that the product effectively suppresses wheat aphid development, with virtually no infestation occurring for 7–14 days, whereas other commercially available formulation had lost their usefulness. Our TpBDMe COF carrier effectively immobilizes dinotefuran, reducing pesticide leaching in soil by 70 % and enhancing the application efficiency of neonicotinoid insecticides. The LD 50 of this product for acute exposure of honey bees doubled the LD50 of the original furosemide at 24 h and was equally effective at 48 h, reducing the toxicity to bees and promoting ecological safety. The results of this work show that this nanocarrier system is highly stable, loadable, insecticidal active, and environmentally friendly, showing great potential in the development of new nanocarriers for use.
Rapid, convenient, and sensitive detection of Bisphenol A (BPA) in complex environmental samples without the need for tedious pre-treatment is crucial for assessing potential health risks. Herein, we present an electrochemical sensing platform using a simple nanochannel-modified electrode, which enables the direct and sensitive detection of BPA in complex samples. A vertically ordered mesoporous silica-nanochannel film (VMSF) with high-density nanochannels is rapidly and stably grown on the surface of a electrochemically activated glassy carbon electrode (p-GCE) by using the electrochemically assisted self-assembly (EASA) method. The high antifouling capability of the VMSF/p-GCE sensor is proven by investigating the electrochemical behavior of BPA in the presence of model coexisting interfering molecules including amylum, protein, surfactant, and humic acid. The VMSF/p-GCE sensor can sensitively detect BPA ranged from 50 to 1.0 μM and 1.0–10.0 μM, with low detection limits (15 nM). Owing to the electrocatalytic performance and high potential resolution of p-GCE, the sensor exhibits high selectivity for BPA detection in the presence of common environmental pollutants, including bisphenol S (BPS), catechol (CC), hydroquinone (HQ), and 4-nitrophenol (4-NP). In combination with the good antifouling property of the VMSF, direct detection of BPA in environmental water samples and soil leaching solution (SLS) is also realized without separation pretreatment. The developed VMSF/p-GCE sensor demonstrated advantages of simple structure, high sensitivity, good antifouling performance, and great potential in direct electroanalysis of endocrine-disrupting compounds in complex samples.
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