磺胺类抗生素在斑马鱼体内的生物富集性及模型预测评估

针对磺胺类抗生素在鱼体内的生物富集特性,采用半静态生物富集测试法,研究磺胺二甲嘧啶(SMT)和磺胺甲恶唑(SMX)在斑马鱼(Brachydanio rerio)体内的生物富集规律及生物富集系数(bio-concentration factor,BCF),并选用3种常用预测模型对2种磺胺类抗生素的BCF值进行估算,比较了估算值与实际测定值,为磺胺类抗生素生物富集性的预测提供依据。研究结果表明,当暴露浓度为0.01 mg·L~(-1)~1.00 mg·L~(-1)时,鱼体对SMT的最大生物富集系数BCF值为1.11,最大富集量出现在暴露24~48 h期间;SMX的最大BCF值为1.15,最大富集量处于暴露96~168 h之间。根据磺胺类抗生素的理化性质,通过比较3种生物富集预测模型获得SMT和SMX的BCF值,发现其中Kow预测模型所得估算值最为接近实测值。因此可利用该模型作为磺胺类抗生素富集性的预测工具,为我国兽药抗生素的环境风险预测和评价提供依据。     

Adsorption of three pharmaceuticals on two magnetic ion-exchange resins

The presence of pharmaceuticals in aquatic environments poses potential risks to the ecology and human health. This study investigated the removal of three widely detected and abundant pharmaceuticals, namely, ibuprofen (IBU), diclofenac (DC), and sulfadiazine (SDZ), by two magnetic ion-exchange resins. The adsorption kinetics of the three adsorbates onto both resins was relatively fast and followed pseudo-second-order kinetics. Despite the different pore structures of the two resins, similar adsorption patterns of DC and SDZ were observed, implying the existence of an ion-exchange mechanism. IBU demonstrated a combination of interactions during the adsorption process. These interactionswere dependent on the specific surface area and functional groups of the resin. The adsorption isothermfittings verified the differences in the behavior of the three pharmaceuticals on the two magnetic ion-exchange resins. The presence of Cl^- and SO₄^2- suppressed the adsorption amount, butwith different inhibition levels for different adsorbates. This work facilitates the understanding of the adsorption behavior andmechanismof pharmaceuticals onmagnetic ion-exchange resins. The results will expand the application of magnetic ion-exchange resins to the removal of pharmaceuticals in waters.     

Cu–Mn–Ce ternary mixed-oxide catalysts for catalytic combustion of toluene

Cu–Mn, Cu–Mn–Ce, and Cu–Ce mixed-oxide catalysts were prepared by a citric acid sol–gel method and then characterized by XRD, BET, H₂-TPR and XPS analyses. Their catalytic properties were investigated in the toluene combustion reaction. Results showed that the Cu–Mn–Ce ternary mixed-oxide catalyst with 1:2:4 mole ratios had the highest catalytic activity, and 99% toluene conversion was achieved at temperatures below 220°C. In the Cu–Mn–Ce catalyst, a portion of Cu and Mn species entered into the CeO₂ fluorite lattice, which led to the formation of a ceria-based solid solution. Excess Cu and Mn oxides existed on the surface of the ceria-based solid solution. The coexistence of Cu–Mn mixed oxides and the ceria-based solid solution resulted in a better synergetic interaction than the Cu–Mn and Cu–Ce catalysts, which promoted catalyst reducibility, increased oxygen mobility, and enhanced the formation of abundant active oxygen species.     

松果去除水体中左氧氟沙星的研究

以松果为原料制备生物吸附剂,通过等温吸附模型和吸附动力学模型对吸附过程进行拟合,分析松果对左氧氟沙星的吸附特征,并考察了左氧氟沙星的最佳吸附条件.结果表明,最佳的吸附条件为pH为8,温度为40℃,吸附剂用量为0.8 g/L,最大吸附量为104.17 mg/g.吸附过程能较好被准二级动力学方程(R2＞0.99)和Langmuir等温吸附模型(R2 ＞0.99)拟合.以农业废弃物松果制备出价廉、高效的新型生物吸附剂,为水体中抗生素的处理提供了一种新的方法.     

Grazing greatly reduces the temporal stability of soil cellulolytic fungal community in a steppe on the Tibetan Plateau

Excessive livestock grazing degrades grasslands ecosystem stability and sustainability by reducing soil organic matter and plant productivity. However, the effects of grazing on soil cellulolytic fungi, an important indicator of the degradation process for soil organic matter, remain less well understood. Using T-RFLP and sequencing methods, we investigated the effects of grazing on the temporal changes of cellulolytic fungal abundance and community structure in dry steppe soils during the growing months from May to September, on the Tibetan Plateau using T-RFLP and sequencing methods. The results demonstrated that the abundance of soil cellulolytic fungi under grazing treatment changed significantly from month to month, and was positively correlated with dissolved organic carbon (DOC) and soil temperature, but negatively correlated with soil pH. Contrastingly, cellulolytic fungal abundance did not change within the fencing treatment (ungrazed conditions). Cellulolytic fungal community structure changed significantly in the growing months in grazed soils, but did not change in fenced soils. Grazing played a key role in determining the community structure of soil cellulolytic fungi by explaining 8.1% of the variation, while pH and DOC explained 4.1% and 4.0%, respectively. Phylogenetically, the cellulolytic fungi were primarily affiliated with Ascomycota (69.65% in relative abundance) and Basidiomycota (30.35%). Therefore, grazing substantially reduced the stability of soil cellulolytic fungal abundance and community structure, as compared with the fencing treatment. Our finding provides a new insight into the responses of organic matter-decomposing microbes for grassland managements.     

Clean and effective removal of Cl(-I) from strongly acidic wastewater by PbO2

Recycling strongly acidic wastewater as diluted H₂SO₄ after contaminants contained being removed was previously proposed, however, Cl(-I), a kind of contaminant contained in strongly acidic wastewater, is difficult to remove, which severely degrades the quality of recycled H₂SO₄. In this study, the removal of Cl(-I) using PbO₂ was investigated and the involved mechanisms were explored. The removal efficiency of Cl(-I) reached 93.38% at 50℃ when PbO₂/Cl(-I) mole ratio reached 2:1. The identification of reaction products shows that Cl(-I) was oxidized to Cl₂, and PbO₂ was reduced to PbSO₄. Cl₂ was absorbed by NaOH to form NaClO, which was used for the regeneration of PbO₂ from the generated PbSO₄. Cl(-I) was removed through two pathways, i.e., surface oxidation and •OH radical oxidation. •OH generated by the reaction of PbO₂ and OH⁻ plays an important role in Cl(-I) removal. The regenerated PbO₂ had excellent performance to remove Cl(-I) after six-time regeneration. This study provided an in-depth understanding on the effective removal of Cl(-I) by the oxidation method.     

Degradation of pyrene by immobilized microorganisms in saline-alkaline soil

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) is very difficult in saline-alkaline soil due to the inhibition of microbial growth under saline-alkaline stress. The microorganisms that can most effectively degrade PAHs were screened by introducing microorganisms immobilized on farm byproducts and assessing the validity of the immobilizing technique for PAHs degradation in pyrene-contaminated saline-alkaline soil. Among the microorganisms examined, it was found that Mycobacterium sp. B2 is the best, and can degrade 82.2% and 83.2% of pyrene for free and immobilized cells after 30 days of incubation. The immobilization technique could increase the degradation of pyrene significantly, especially for fungi. The degradation of pyrene by the immobilized microorganisms Mucor sp. F2, fungal consortium MF and co-cultures of MB+MF was increased by 161.7% (P < 0.05), 60.1% (P < 0.05) and 59.6% (P < 0.05) after 30 days, respectively, when compared with free F2, MF and MB+MF. Scanning electron micrographs of the immobilized microstructure proved the positive effects of the immobilized microbial technique on pyrene remediation in saline-alkaline soil, as the interspace of the carrier material structure was relatively large, providing enough space for cell growth. Co-cultures of different bacterial and fungal species showed different abilities to degrade PAHs. The present study suggests that Mycobacterium sp. B2 can be employed for in situ bioremediation of PAHs in saline-alkaline soil, and immobilization of fungi on farm byproducts and nutrients as carriers will enhance fungus PAH-degradation ability in saline-alkaline soil.     

山仔水库沉积物蓝藻复苏试验研究

采用正交试验考察了温度、光照、营养盐和物理扰动4个因素对山仔水库冬季沉积物中蓝藻复苏的影响,每个因素设置两个水平,培养周期为6 d,并以蓝藻复苏量为考察指标.结果表明,温度和光照为蓝藻复苏的主要影响因子,上覆水体的营养盐、物理扰动对沉积物中蓝藻门复苏的影响作用不显著,不同的蓝藻种属对温度和光照条件的响应程度不完全一致,蓝藻门微囊藻属(Microcystis)对温度和光照的复苏响应显著,颤藻属(Oscillatoria)仅对温度的复苏响应显著.同时,通过设置6.0~16.0 ℃之间6个温度梯度及50和2000 lx两个光照梯度,进行了沉积物柱状样复苏模拟实验.结果显示,山仔水库冬季沉积物微囊藻属和颤藻属在10 ℃左右开始复苏,微囊藻属对光的敏感性使其更容易处于优势地位.     

Influence of hydroxypropylcyclodextrins on the toxicity of mixtures

We studied the influence of hydroxypropylcyclodextrins (HPCDs) on the toxicity of some mixtures. Using the Photobacterium phosphoreum toxicity test, the joint toxicological effect for Mixture I (containing p-nitrobenzaldehyde and 1-nitronaphthalene) and Mixture II (containing p-nitrobenzaldehyde and malononitrile) were determined in water and in aqueous solutions of HPCDs. The results indicate that, although the toxicological joint effect for Mixture I (simple addition) differs from that of Mixture II (synergism), alpha- and beta-HPCD can significantly reduce the toxicity of the test compounds, whereas gamma-HPCD has only a slight effect. Explanations for these observations are given that invoke the molecular structure of the individual chemicals as well as the structures of HPCDs. This provides information to assist the application of HPCDs in remediation of environmental pollution.