电化学还原-氧化工艺降解4-氯酚的毒性研究

采用紫外光还原法制备了Pd-Fe/石墨烯催化阴极,并以Ti/IrO_2/RuO_2为阳极,构成三电极体系(双阴极)和两电极体系(单阴极)的电化学还原-氧化降解工艺,分别对4-氯酚进行降解.采用离子色谱、高效液相色谱、TOC仪对4-氯酚降解过程中中间产物及其浓度进行测定.根据公式计算降解过程中理论计算毒性值,应用发光细菌法测定降解过程中的实际毒性值,对理论计算毒性值与实际毒性值进行比较,分析不同体系下降解过程中毒性的变化规律.结果表明,两种工艺体系在最佳降解条件下,阴极室毒性均呈下降的趋势,由于降解过程中在阳极室生成高毒性的苯醌,阳极室毒性均先升高后降低.通过相关性分析得到,两种体系理论计算毒性与实际毒性在P=0.01水平下,相关性系数均为1,显著相关,表明降解过程中实际毒性的测定结果真实可靠.降解至120 min时,三电极体系毒性小于两电极体系,表明三电极体系优于两电极体系.据此提出实际毒性测定方法在电化学还原-氧化工艺降解氯酚类有机废水毒性测试的工业应用中有着广泛的前景.     

林丹短期暴露下的斑马鱼(Brachydanio rerio)组织学变化

以斑马鱼(Brachydaniorerio)为受试生物,初步探讨了林丹对斑马鱼的急性毒性以及不同浓度(0.01μg·L-1、1.0μg·L-1、100.0μg·L-1)的林丹暴露36d后对斑马鱼鳃和肝组织结构变化的影响.结果表明,林丹对斑马鱼96h-LC50为97.98μg·L-1,95%可信限为94.38￣101.72μg·L-1.当林丹浓度为0.01μg·L-1时,斑马鱼的鳃和肝组织结构未发生明显变化,而暴露在1.0μg·L-1和100.0μg·L-1林丹溶液中的斑马鱼的鳃和肝组织结构变化显著.斑马鱼鳃组织变化为:上皮细胞残损、脱落,鳃小片上皮细胞水肿,柱细胞变形.斑马鱼肝组织变化为:部分肝细胞肿大,细胞核萎缩变形或偏离细胞中心,胞质疏松,空泡明显增加,细胞质中可见脂沉积.与1.0μg·L-1林丹暴露相比,暴露在100μg·L-1林丹溶液中的斑马鱼鳃和肝组织结构受到的损害更为严重.     

拟除虫菊酯杀虫剂对水生态系统的毒性作用

拟除虫菊酯杀虫剂主要用于防治棉田、菜地、果树和茶叶上的农业害虫以及卫生害虫,也用于渔业生产上杀灭寄生虫。近几年来其使用量越来越大,是传统有机磷农药的替代品。它具有高效广谱、低残留的特点,对光稳定,在哺乳动物体内代谢、排泄迅速,但是对水生态系统危害较大。报道了拟除虫菊酯杀虫剂对水生生物的急、慢性毒性和中毒机理的研究进展,阐述了有待研究的方向。     

In situ formation of bimetallic FeNi nanoparticles on sand through green technology: Application for tetracycline removal

• In situ preparation of FeNi nanoparticles on the sand via green synthesis approach. • Removal of tetracycline using GS-FeNi in batch and column study. • Both reductive degradation and sorption played crucial role the process. • Reusability of GS-FeNi showed about 77.39±4.3% removal on 4th cycle. • TC by-products after interaction showed less toxic as compared with TC. In this study, FeNi nanoparticles were green synthesized using Punica granatum (pomegranate) peel extract, and these nanoparticles were also formed in situ over quartz sand (GS-FeNi) for removal of tetracycline (TC). Under the optimized operating conditions, (GS-FeNi concentration: 1.5% w/v; concentration of TC: 20 mg/L; interaction period: 180 min), 99±0.2% TC removal was achieved in the batch reactor. The removal capacity was 181±1 mg/g. A detailed characterization of the sorbent and the solution before and after the interaction revealed that the removal mechanism(s) involved both the sorption and degradation of TC. The reusability of reactant was assessed for four cycles of operation, and 77±4% of TC removal was obtained in the cycle. To judge the environmental sustainability of the process, residual toxicity assay of the interacted TC solution was performed with indicator bacteria (Bacillus and Pseudomonas) and algae (Chlorella sp.), which confirmed a substantial decrease in the toxicity. The continuous column studies were undertaken in the packed bed reactors using GS-FeNi. Employing the optimized conditions, quite high removal efficiency (978±5 mg/g) was obtained in the columns. The application of GS-FeNi for antibiotic removal was further evaluated in lake water, tap water, and ground water spiked with TC, and the removal capacity achieved was found to be 781±5, 712±5, and 687±3 mg/g, respectively. This work can pave the way for treatment of antibiotics and other pollutants in the reactors using novel green composites prepared from fruit wastes.     

兽药抗生素对生态环境的混合毒性研究进展

抗生素是环境中普遍存在的污染物,畜牧水产养殖是其主要来源之一.环境中可能同时存在多种抗生素残留,因此单一药物的毒性评价难以反映抗生素对生态环境的影响,应探究其混合物的毒性效应.本文在总结大量文献的基础上,介绍了兽用抗生素的残留现状,总结了兽用抗生素对生态环境的混合毒性研究进展,讨论了兽用抗生素残留对土壤生物和水生生物的...     

AOX漂白废水对黑鲷鱼卵及仔鱼的毒性效应

用含AOX的造纸漂白废水对人工养殖的黑鲷鱼卵和早期仔鱼进行了毒性实验.结果表明:对于AOX漂白废水的毒性,黑鲷鱼卵胚胎阶段比早期仔鱼阶段更为敏感.高浓度的AOX漂白废水对鱼卵孵化产生一定的抑制作用,对仔鱼产生尾部畸形和致死现象,鱼卵孵化的EC50和95%置信区间分别为0.018和0～0.087 mL/mL;仔鱼72 h LC50和96h LC50分别为0.557和0.774 mL/mL,72 h的LOEC和NOEC分别为0.032和0.001 mL/mL,96 h的LOEC和NOEC分别为0.003和0.001 mL/mL.表明仔鱼对AOX漂白废水的毒性敏感性随着时间的推移而逐渐减弱.      

废水中2,6-二硝基酚厌氧毒性和降解动力学研究

在中温(35℃±1℃)厌氧条件下,以葡萄糖为共基质,采用间歇实验方法,研究了2,6-二硝基酚(2,6-DNP)的厌氧产甲烷毒性和厌氧降解动力学.厌氧毒性试验(ATA)以累计产甲烷量和相对活性(RA)为指标,评价了不同浓度2,6-DNP对产甲烷菌的抑制程度;结果表明,2,6-DNP浓度＜20 mg/L时,对产甲烷菌没有抑制作用,浓度为40 mg/L时产生轻度抑制,浓度为80～120 mg/L时产生重度抑制;24 h 2,6-DNP的75%、50%、25%相对抑制浓度分别为30、70和＞120 mg/L.2,6-DNP降解动力学可用Haldane方程来描述,利用非线性拟合求得动力学参数Ks、Rm、Ki分别为179.7 mg/L、4.84 mg/g VSS·h、206.5 mg/L,方差R2=0.94,拟合效果很好.     

Effect of Cadmium on Microbial Activity and a Ryegrass Crop in Two Semiarid Soils

Soil pollution with Cd is an environmental problem common in the world, and it is necessary to establish what Cd concentrations in soil could be dangerous to its fertility from toxicity effects and the risk of transference of this element to plants and other organisms of the food chain. In this study, we assessed Cd toxicity on soil microorganisms and plants in two semiarid soils (uncultivated and cultivated). Soil ATP content, dehydrogenase activity, and plant growth were measured in the two soils spiked with concentrations ranging from 3 to 8000 mg Cd/kg soil and incubated for 3 h, 20 days, and 60 days. The Cd concentrations that produced 5%; 10%;, and 50%; inhibition of each of the two soil microbiological parameter studied (ecological dose, ED, values) were calculated using two different mathematical models. Also, the effect of Cd concentration on plant growth of ryegrass (Lolium perenne, L.) was studied in the two soils. The Cd ED values calculated for soil dehydrogenase activity and ATP content were higher in the agricultural soils than in the bare soil. For ATP inhibition, higher ED values were calculated than for dehydrogenase activity inhibition. The average yields of ryegrass were reduced from 5.03 to 3.56 g in abandoned soil and from 4.21 to 1.15 g in agricultural soil with increasing concentrations of Cd in the soil. Plant growth was totally inhibited in abandoned and agricultural soils at Cd concentrations above 2000 and 5000 mg/kg soil, respectively. There was a positive correlation between the concentration of Cd in the plants and the total or DTPA-extractable concentrations of Cd in the soil.     

氯化消毒过程对抗生素的降解行为及其毒性效应的影响研究进展

抗生素的大量使用导致其通过各种途径进入到污水处理厂、地表水甚至饮用水源水中.在污水处理厂二级出水排放之前以及自来水的生产和供应过程中,都必须进行氯化消毒处理以杀灭病原微生物.在此过程中,抗生素一方面可能被氯化降解,另一方面也可能转化成毒性更高的降解产物.因此,了解抗生素在氯化消毒过程中的降解行为对于明确其生态和健康风险...     

二氧化氯对摇蚊幼虫的毒效试验及影响因素

以水厂原水为试验水样,研究了二氧化氯对摇蚊不同龄期幼虫的毒性效果（24 h）,并考察了温度和接触时间对二氧化氯毒性效果的影响.结果表明,二氧化氯对摇蚊幼虫具有极为显著的毒性作用,25℃时二氧化氯对4龄幼虫的24h半致死浓度（LC₅₀）为0 .41 mg/L.二氧化氯对摇蚊幼虫的毒力随幼虫龄期的增长而降低,1龄幼虫对二氧化氯最敏感,其中二氧化氯对4龄幼虫的LC₅₀是1龄幼虫的1 .78倍.二氧化氯的毒力在一定范围内符合正温度系数规律,二氧化氯对4龄幼虫的毒力在15～30℃范围内增加了2 .16倍.接触时间从12 h延长至24 h,二氧化氯对4龄幼虫的毒力增幅显著;当接触时间至36 h,与接触24 h相比毒力增幅不明显.