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.     

内循环活性炭生物流化床处理农药生产废水的试验研究

采用内循环活性炭生物流化床反应器处理某农药厂生产废水,通过试验研究了该反应器在室温条件下处理农药生产废水的性能.结果表明:当进水pH值控制在7.0～7.5、水力停留时间为6h、曝气量控制在使活性炭处于流化状态时,CODcr的去除率为50％,总氮的去除率为32.33％,同时可生化性明显提高,生物毒性有所降低.     

氯代苯胺对斑马鱼的急性毒性的电性拓扑研究

基于拓扑理论计算了7种氯代苯胺分子的Kier和Hall的原子类型电性拓扑状态指数(E)f。通过多元线性回归和最佳变量子集回归方法建立了氯代苯胺对斑马鱼急性毒性(pLC5)0与其电性拓扑状态指数的最佳二元定量构效关系(QSAR)模型,其传统判定系数(R)2为0.978,逐一剔除法(LOO)的交互验证系数(Q)2为0.964。根据统计学观点,该模型具有良好的稳健性及预测能力,用该模型给出的估算值和实验值非常接近,优于相关文献的计算结果。从进入该QSAR模型的2个电性拓扑状态指数(E9,E2)6可见,所建的数学方程显示芳环内=C<及硝基中氮原子(=N≤)是影响其pLC50的主要结构因素。     

基于析因设计的多种重金属对发光菌联合毒性研究

文章采用析因设计的方法,研究沉积物水浸提液掺杂的多种重金属Cu、Cd、Zn、Pb和Ni对发光菌的联合毒性。通过对试验结果进行方差分析和多元线性回归,建立了重金属浓度和发光菌发光抑制率的关系模型:T=97.983Cu+41.111Cd-27.297Zn+129.869Pb+16.715Ni-5 803.639Cu*Cd+2 270.182Cd*Zn-6 411.870Cd*Pb-675.052Cd*Ni-3 108.544Pb*Ni+15 9552.434Cd*Pb*Ni+274 718.434Zn*Pb*Ni。模型分析结果表明:Zn对联合毒性产生负的影响,Cu、Cd、Pb、Ni对联合毒性具有正的贡献;Cd*Zn二元交互作用和Cd*Pb*Ni、Zn*Pb*Ni三元交互作用表现为协同作用,Cu*Cd、Cd*Pb、Cd*Ni、Pb*Ni二元交互作用表现为拮抗作用,而重金属四元和五元交互作用对联合毒性的贡献不显著。上述重金属联合毒性的作用可为沉积物中重金属复合污染控制提供参考。     

稀土钇对蚯蚓的急性毒性及蚓体内蓄积研究

文章以蚯蚓为指示生物,分别采用滤纸接触法和自然土壤法研究了稀土元素钇对蚯蚓的急性毒性效应。结果表明,滤纸接触法测得钇对蚯蚓的半数致死浓度LC50为0.18 g/L;土壤法所测LC50值为1.08 g/kg。可见,稀土钇对蚯蚓具有毒性作用,但属低毒级,并且自然土壤法中蚯蚓的半数致死浓度要低于滤纸接触法中的结果。应用ICP-AES分别研究了2种实验方法中钇在蚯蚓体内的富集情况,发现硝酸钇浓度及染毒时间、蚯蚓的死亡率及速度和钇在蚯蚓体内的富集三者存在显著的相关性。     

基于GLM模型和神经网络研究芳烃化合物对藻类毒性

工业的快速发展和溢油事故的频繁发生所产生的大量芳烃化合物正威胁海洋生态系统的健康,建立芳烃化合物物化性质与小球藻急性毒性间的非线性模型,是预测未知芳烃化合物对藻类毒性的主要手段之一.本研究以实验获取的25种芳烃化合物对小球藻96h的毒性数据为基础,采用密度泛函理论(DFT)中的B3LYP方法,在6-311G**基组上全优化计算25种芳烃化合物结构参数和热力学参数,通过逐步广义线性回归(GLM)、小波神经网络(WNN)和T-S模糊神经网络(T-SFNN)等方法,对芳烃化合物物化性质和藻类抑制毒性的非线性关系进行拟合和逼近.F检验表明,逐步GLM方程是显著的(p<0.001).配对t检验表明,GLM、WNN、T-SFNN3种模型都是可信的;决定系数(R2>0.96)表明3个模型具有很高的精确性.上述结果证明本文建立的模型具有良好的拟合度和解释能力,可以预测未知芳烃化合物对小球藻的急性毒性.模型误差计算结果表明,WNN的精度最高(mse=0.0076,mae=0.0533),采用WNN方法进行建模,预测未知芳烃化合物对小球藻的急性毒性是最合适的.     

Effects of rare earth elements La and Yb on the morphological and functional development of zebrafish embryos

In recent years, with the wide applications and mineral exploitation of rare earth elements, their potential environmental and health effects have caused increasing public concern. Effect of rare earth elements La and Yb on the morphological and functional development of zebrafish embryos were studied. The embryos were exposed to La³⁺ or Yb³⁺ at 0, 0.01, 0.1, 0.3, 0.5 and 1.0 mmol/L, respectively. Early life stage parameters such as egg and embryo mortality, gastrula development, tail detachment, eyes, somite formation, circulatory system, pigmentation, malformations, hatching rate, length of larvae and mortality were investigated. The results showed La³⁺ and Yb³⁺ delayed zebrafish embryo and larval development, decreased survival and hatching rates, and caused tail malformation in a concentration-dependent way. Moreover, heavy rare-earth ytterbium led to more severe acute toxicity of zebrafish embryo than light rare-earth lanthanum.     

Toxicity and subcellular distribution of cadmium in wheat as affected by dissolved organic acids

We aim to investigate the effects of humic acid (HA) and citric acid (CA) on the toxicity and subcellular distribution of Cd in wheat. Results show that the toxicity and uptake of Cd decreased with increasing HA. The EC₅₀ values of Cd increased from 3.36 μmol/L to 4.96 and 7.33 μmol/L at 50 and 250 mg/L HA, respectively, but decreased to 1.39 μmol/L in the presence of CA based on free ion activity model (FIAM). HA decreased the relative subcellular distribution of Cd in the heat-denatured proteins (decreased from 54% to 33%) but increased Cd in the heat-stable proteins in root (from 25% to 50%) at 7.61 μmol/L {Cd²⁺} (free Cd activity), which resulted in decreasing Cd toxicity. However, CA increased Cd toxicity due to the increased internalization of Cd although the relative subcellular distributions of Cd exhibited a decrease in the heat-denatured proteins and increase in the granule fraction compared to the control at high-level Cd. The FIAM could not predict the toxicity of Cd in the presence of organic acids. Alternatively, the internal Cd accumulation and subcellular Cd concentration were better to describe the toxicity of Cd to wheat.     

低剂量长期铅暴露对雄性黑斑蛙精巢组织关键酶活性的影响

在实验条件下,将健康的性成熟雄性黑斑蛙暴露于0.1、0.2、0.4、0.8和1.6mg·L-1的Pb2+溶液中30d,以Ca2+-ATP酶、Na+-K+-ATP酶、Ca2+-Mg2+-ATP酶、β-葡萄糖醛酸苷酶(β-DG)、乳酸脱氢酶(LDH)和酸性磷酸酶(ACP)活性为指标,进行了长期铅暴露对雄性黑斑蛙生殖毒性的研究.结果表明:随着铅染毒剂量的增加,Ca2+-ATP酶和Na+-K+-ATP酶活性被诱导,Ca2+-Mg2+-ATP酶活性被抑制,当Ca2+-Mg2+-ATP酶的抑制程度超过Ca2+-ATP酶和Na+-K+-ATP酶的代偿机制时,会抑制精子的发生,进而导致雄性生殖毒性;在1.6mg·L-1Pb2+处理下,ACP酶被显著抑制,提示支持细胞受损,精子总数受到影响;在0.4mg·L-1Pb2+处理下,LDH酶被显著抑制,提示生精细胞受损,精子质量受到影响.     

镉和乙草胺对少根紫萍的毒性效应

联合毒性实验在水环境污染评价中非常重要.本文以少根紫萍(Spirodela Oligorrhiza)为研究对象,研究了重金属Cd和除草剂乙草胺对少根紫萍生长的单一毒性和联合毒性效应.实验结果表明:Cd、乙草胺及对少根紫萍的96h-IC50分别为4.77mg/L和6.95mg/L,在浓度1:1的情况下,Cd与乙草胺共存对少根紫萍的96h-IC50为1.41mg/L,采用Marking相加指数法求得相加指数AI为1.00,大于零,为协同作用.同时,随着Cd、乙草胺处理浓度的增加,少根紫萍叶绿素a的浓度下降,其中Cd对叶绿素a的影响大于乙草胺,复合污染对叶绿素a的影响明显大于单一污染,也表现为协同作用.另外,本文还对少根紫萍生长抑制试验进行了探讨,建议使用植物体数和重复间的偏差作为衡量试验质量的指标.