Distribution Characteristics and Risk Assessment of 57 Pesticides in Farmland Soil and the Surrounding Water.

To investigate the effect of pesticide use on surface water, the concentration and distribution characteristics of 57 pesticides and 3 degradation products were analyzed in the farmland soil and surface water in the Xingkai Lake area, including water from paddy fields, drainages and the Xingkai Lake, in Heilongjiang Province, China. Forty-three pesticides and three degradation products were detected in farmland soil. In dry field (corn and soybean field) soil, the main detected pesticides were atrazine and acetochlor with mean concentrations of 26.09 ng·g-1 and 49.08 ng·g-1, respectively. In paddy field soil, oxadiazon, mefenacet and chlorpyrifos were the main detected pesticides with mean concentrations of 14.32 ng·g-1, 78.60 ng·g-1 and 20.03 ng·g-1, respectively. In the surrounding water, including water from paddy fields, drainages and Xingkai Lake, the total concentrations of contaminants detected in the water samples ranged from 71.19 ng·L-1 to 10,145.76 ng·L-1. Of the three sampling periods, the mean concentration of contaminants in the water exhibited its peak during the vegetative period. In the analysis of the drainage water, the primary pesticides detected were atrazine, acetochlor and buprofezin with mean concentrations of 354.83 ng·L-1, 109.09 ng·L-1 and 254.56 ng·L-1, respectively. Atrazine, simetryn, buprofezin and isoprothiolane were the main pesticides detected in Xingkai Lake water, with the mean concentrations of 222.35 ng·L-1, 112.76 ng·L-1, 301.87 ng·L-1 and 138.02 ng·L-1, respectively. The concentrations of contaminants could be correlated with drainage, Da Xingkai Lake and Xiao Xingkai Lake water (ρ > 0.8) suggested that the source of these contaminants in drainage and Xingkai Lake water could be the same. The maximum potentially affected fraction (PAF) values of atrazine, chlorpyrifos and prometryn were higher than 5% in Xingkai Lake water, resulting in high ecological risks.

A novel polydopamine-modified metal organic frameworks catalyst with enhanced catalytic performance for efficient degradation of sulfamethoxazole in wastewater.

In this study, a novel polydopamine (PDA)-modified metal organic frameworks (MOFs) catalyst (MIL/PDA) was successfully fabricated to activate persulfate (PS) for the degradation of sulfamethoxazole (SMX) in wastewater. The experimental results indicated that PDA-modified catalyst exhibited superior catalytic performance and enhanced the degradation of SMX (91.5%) compared to pure MOFs. The physical-chemical properties of the MIL/PDA catalyst were comprehensively characterized, and the applications in the catalytic degradation of SMX were evaluated. It was found that the modification of PDA enhanced the electron transfer, while promoting the redox cycle of Fe(III)/Fe(II), which in turn boosted the production of active oxygen species. Furthermore, MIL/PDA showed high stability and reusable performance over multiple cycles. Both radical and non-radical pathways were jointly involved in the activation process of PS were confirmed by quenching experiments combined with electron paramagnetic resonance (EPR). Based on this, the possible mechanism of the catalytic reaction was investigated. Finally, five degradation pathways of SMX degradation were proposed according to the results of liquid chromatography-mass spectrometry (LC-MS). This work provided a new insight into the design of novel and efficient heterogeneous catalysts for advanced wastewater treatment.

Modulated construction of Fe-based MOF via formic acid modulator for enhanced degradation of sulfamethoxazole：Design, degradation pathways, and mechanism.

Metal-organic frameworks (MOFs) have attracted more attention because of their excellent environmental catalytic capabilities. Modulation approach as an advanced assistant strategy is vital essential to enhancing the performance of MOFs. In this study, the modulated method was used to successfully synthesize a group of Fe-based MOFs, with formic acid as the modulator on the synthesis mixture. The most modulated sample Fe-MOFs-2 exhibit high specific surface areas and higher catalytic activity, which could effectively degrade SMX via PS activation, with almost 95% removal efficiency within 120 min. The results revealed that the % RSE of modulated Fe-MOFs-2 increased from 2.31 to 3.27 when compared with the origin Fe-MOFs. This may be due to the addition of formic acid induces the formation of more coordinatively unsaturated metal sites in the catalyst, resulting in structural defects. In addition, the quenching experiment and EPR analysis verified SO4-·and·OH as the major active free radicals in the degradation process. Modulated Fe-MOFs-2 demonstrated good reusability and stability under fifth cycles. Finally, four possible degradation pathways and catalytic mechanism of Fe-MOFs-2 was tentatively proposed. Our work provides insights into the rational design of modulated Fe-MOFs as promising heterogeneous catalysts for advanced wastewater treatment.

Protective effects of cortex fraxini coumarines against oxonate-induced hyperuricemia and renal dysfunction in mice.

The aim of the present study was to investigate the effects of cortex fraxini coumarines esculetin, esculin, fraxetin and fraxin on renal dysfunction and expression abnormality of renal organic ion transporters in hyperuricemic animals. Mice were orally given 250 mg/kg oxonate for seven consecutive days to induce hyperuricemia and renal dysfunction. After 1h of oxonate induction daily, animals were orally treated with esculetin, esculin, fraxetin and fraxin at 20 and 40 mg/kg, respectively. Esculetin, esculin, fraxetin and fraxin significantly decreased serum urate, creatinine and blood urea nitrogen levels and increased urine urate and creatinine excretion in hyperuricemic mice. Esculetin and esculin up-regulated expressions of renal organic anion transporter 1 (mOAT1), organic cation and carnitine transporters (mOCT1-2 and mOCTN1-2), but failed to affect renal glucose transporter 9 (mGLUT9) and urate transporter 1 (mURAT1) in this model. Fraxetin specifically inhibited renal mURAT1, while fraxin extensively interacted with renal mGLUT9, mURAT1, mOAT1 and mOCT1 in hyperuricemic mice. Furthermore, esculetin, fraxetin and fraxin increased mABCG2 mRNA expression and decreased its protein levels in renal apical membrane in hyperuricemic mice. These results indicate that esculetin and esculin have beneficial effects on hyperuricemia and renal dysfunction, resulting in restoration of mOAT1, mOCT1-2 and mOCTN1-2, and fraxetin and fraxin enhance urate excretion partly by inhibiting mURAT1 or mGLUT9 in kidney of hyperuricemic mice. Regulation of mABCG2 by cortex fraxini coumarines may be partly contributed to their beneficial actions. This study provides an evidence to support clinical therapeutic effects of cortex fraxini coumarines on hyperuricemia with renal dysfunction.