Bioavailability assessment of difenoconazole to earthworms (Eisenia fetida) in soil by oleic acid-embedded cellulose acetate membrane.

Passive sampling technology is widely used to evaluate the bioavailability of pollutants. However, relatively few studies have used passive sampling membranes (PSMs) to evaluate the environmental risks of pollutants in soil, particularly pesticides. Here, the bioavailability of difenoconazole to earthworms (Eisenia fetida) was evaluated using an oleic acid-embedded cellulose acetate membrane (OECAM) for the first time. Difenoconazole reached 94 % equilibrium (T94%) within 1 d in OECAM. For soil pore water, the freely dissolved concentration (Cfree) of difenoconazole was determined using OECAM (R2 = 0.969). In the soil system, a strong linear correlation between the difenoconazole concentration in OECAM and earthworms was observed (R2 = 0.913). The bioavailability of difenoconazole was affected by the soil type and biochar content. The higher the content of soil organic matter and biochar, the lower the concentration of difenoconazole in earthworms, OECAM, and soil pore water. The concentrations of difenoconazole in pore water, earthworms, and OECAM decreased by 65.3, 42.0, and 41.6 %, respectively, when 0.5 % biochar was added. Difenoconazole mainly enters OECAM and earthworms through passive diffusion with similar uptake pathways. Therefore, the bioavailability of difenoconazole to earthworms in different soils can be evaluated using the OECAM.

Abiotic transformation of kresoxim-methyl in aquatic environments: Structure elucidation of transformation products by LC-HRMS and toxicity assessment.

In this study, abiotic transformation of an important strobilurin fungicide, kresoxim-methyl, was investigated under controlled laboratory conditions for the first time by studying its kinetics of hydrolysis and photolysis, degradation pathways and toxicity of possibly formed transformation products (TPs). The results indicated that kresoxim-methyl showed a fast degradation in pH9 solutions with DT50 of 0.5 d but relatively stable under neutral or acidic environments in the dark. It was prone to photochemical reactions under simulated sunlight, and the photolysis behavior was easily affected by different natural substances such as humic acid (HA), Fe3+and NO3-which are ubiquitous in natural water, showing the complexity of degradation mechanisms and pathways of this chemical compound. The potential multiple photo-transformation pathways via photoisomerization, hydrolyzation of methyl ester, hydroxylation, cleavage of oxime ether and cleavage of benzyl ether were observed. 18 TPs generated from these transformations were structurally elucidated based on an integrated workflow combining suspect and nontarget screening by high resolution mass spectrum (HRMS), and two of them were confirmed with reference standards. Most of TPs, as far as we know, have never been described before. The in-silico toxicity assessment showed that some of TPs were still toxic or very toxic to aquatic organisms, although they exhibit lower aquatic toxicity compared to the parent compound. Therefore, the potential hazards of the TPs of kresoxim-methyl merits further evaluation.

[Surgical selection and efficacy assessment for membranous urethral trauma caused by pelvic fracture].

OBJECTIVE: To explore selection and efficacy assessment for membranous urethral trauma caused by pelvic fracture. METHODS: From June 2000 to August 2010, 72 patients with membranous urethral trauma caused by pelvic fracture were selected. There were 46 males and 26 females,ranging age from 26 to 62 years (averaged 35.2 years). The time from injury to hospitalization time was 1 to 3 hours. According to Tile pelvic fracture classification, there were 8 patients with type A, 45 patients with type B, 19 patients with type C. Thirty of the 35 patients with partial rupture of posterior urethral were treated by catheterization,5 patients treated by rupture anastomosis on the stage I combined with cystostomy; 25 of the 37 patients with complete rupture of posterior urethra were treated by early realignment, and 12 patients were treated by cystostomy. Urinary incontinence, impotence and urethrostenosis were evaluated. RESULTS: All patients were followed up for 5 to 10 years (mean 7.7 years). Incidence of urethrostenosis, impotence and urinary incontinence in patients treated by cystostomy were significantly higher than rupture anastomosis on the stage I and early realignment (P < 0.05); while incidence in patients treated by catheterization was significantly lower than other groups (P < 0.05). CONCLUSION: For patients with partial rupture of posterior urethral, catheterization and rupture anastomosis on the stage I are preferred methods; while patients with complete rupture of posterior urethra, early realignment is a preferred method with advantages of simple operation and less complications.