采用支持向量机算法优化电化学处理油田污水的工艺参数

采用支持向量机(SVM)算法,将Box-Behnken设计法与支持向量回归算法(SVR)实验参数优化软件相结合,优化电化学去除油田污水COD的工艺参数。通过量子粒子群算法对SVM算法参数进行优化,从建立的回归模型中找到工艺参数的全局最佳点:电解时间60 min,电解电流3 A,三维电极填充料中石英砂质量695 g。模型得到的COD理论最优去除率为92.48%,验证实验得到的COD去除率为91.43%。     

Metal contents of marine turtle eggs (Chelonia mydas; Lepidochelys olivacea) from the tropical eastern pacific and the implications for human health

Concentrations of eight elements were measured in Chelonia mydas and Lepidochelys olivacea eggs collected along the Pacific coast of Panama. Manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), and mercury (Hg) concentrations were similar to previous reports of these species from around the world, while lead (Pb) was lower than previous reports. Cd posed the highest health risk to people who regularly eat the eggs, with average consumption rates leading to target hazard quotients (THQ) of up to 0.35 ± 0.15. Our conclusions indicate that current turtle egg consumption in isolated, coastal Pacific communities may pose a health concern for young children, and that youth and young adults should limit their consumption of turtle eggs to reduce their total intake of nonessential metals.     

太湖春季和秋季蓝藻光合作用活性研究

采用Phyto-PAM浮游植物分析仪测定太湖蓝藻光合作用活性的时空间分布.结果表明,太湖蓝藻光合活性具有显著的时空差异:春季蓝藻的最大光量子产量F_v/F_m (可变荧光和最大荧光之比)和实际光量子产量F_v'/F_m'分别在0.35~0.49和0.16~0.29之间,秋季蓝藻分别在 0.33~0.53和0.21~0.43之间,太湖秋季蓝藻的最大光合作用能力和实际光合作用能力大于春季蓝藻.春季和秋季蓝藻的非光化学淬灭NPQ(non-photochemical quenching)分别在0.012~0.17和0.035~0.26之间,秋季蓝藻的NPQ高于春季蓝藻,说明秋季蓝藻的自我保护能力高于春季蓝藻.快速光响应曲线(Rapid light curve, RLC)的特征参数表明春季蓝藻的光能利用效率、最大电子传递速率和光饱和强度点高于秋季蓝藻;从空间分布来看,蓝藻的最大光合作用能力、实际光合作用能力和光合作用效率在营养水平低和有水草分布的湖区相对较低,富营养化水平高的湖区则相对较高.因此,降低太湖营养盐浓度,恢复水生植物,能够抑制蓝藻的光合作用活性和生长,从而降低蓝藻水华强度.     

Enhanced photocatalytic activity of quantum-dot-sensitized one-dimensionally-ordered ZnO nanorod photocatalyst

An efficient photocatalyst was fabricated by assembling quantum dots （QDs） onto one-dimensionally-ordered ZnO nanorods, and the photocatalytic properties for Methyl Orange degradation were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-Vis-NIR absorption spectroscopy and photoluminescence. The results indicate that the catalyst with assembled QDs is more favorable for the degradation than the pristine ZnO nanorods. The QDs with core-shell structure lower the photocatalytic ability due to the higher carder transport barrier of the ZnS shell layer. Besides its degradation efficiency, the photocatalyst has several advantages given that the one-dimensionally-ordered ZnO nanorods have been grown directly on indium tin oxide substrates. The article provides a new method to design an effective and easily recyclable photocatalyst.     

CdSe/ZnS量子点对稀有鮈鲫胚胎发育的影响及其氧化应激作用

本研究以稀有鮈鲫(Gobiocypris rarus)为对象,研究了不同浓度CdSe/ZnS量子点(QDs)暴露下,稀有鮈鲫胚胎发育过程中自主运动频率、内心率和体长的变化,以及利用体内超氧化物歧化酶(SOD)和丙二醛(MDA)作为毒性指标,反映CdSe/ZnS QDs暴露对稀有鮈鲫胚胎发育的氧化应激作用.结果显示:CdSe/ZnS QDs对稀有鮈鲫胚胎72 hpf(hours post fertilization)的半致死浓度(LC50)为319.629 nmol·L-1,96 hpf的半致畸浓度(EC50)为203.312 nmol·L-1.CdSe/ZnS QDs暴露不仅影响稀有鮈鲫胚胎死亡率、畸形率、自主运动频率、孵化时间和孵化率,而且使其内心率减缓、体长缩短,导致胚胎卵凝结,心包囊肿,出现脊椎弯曲等多种毒性现象.同时发现,CdSe/ZnS QDs暴露导致稀有鮈鲫体内MDA含量增加以及SOD活力的降低.这表明CdSe/ZnS QDs对稀有鮈鲫胚胎发育具有致畸、致死作用,而氧化应激可能是引起其胚胎致畸、致死的重要机制之一.     

A metal-free composite photocatalyst of graphene quantum dots deposited on red phosphorus

A simple approach to enhance the photocatalytic activity of red phosphorus(P) was developed.A mechanical ball milling method was applied to reduce the size of red P and to deposit graphene quantum dots onto red P. The product was characterized by scanning electron microscopy, transmission electron microscopy, contact angle measurements, zeta-potential measurements, X-ray diffraction and UV–vis absorption spectroscopy. The product exhibited high visible-light-driven photocatalytic performance in the photodegradation of rhodamine B.     

BiOBr/Bi2MoO6异质结的构筑及对甲基橙的吸附/光催化性能的协同作用机制

采用简单的沉积-沉淀法合成了BiOBr/Bi_2MoO_6(BOB/BMO)异质结,采用XRD、XPS、TEM、SEM、EDS、FT-IR、UV-Vis-DRS、PL、PC和EIS等测试技术对光催化剂的物相组成、形貌、光吸收特性和光电化学性能等进行系统表征,并以模型污染物甲基橙(MO)的吸附和光催化降解作为探针来评价BiOBr/Bi_2MoO_6异质结的吸附性能与光催化活性增强机制.SEM和TEM分析结果表明,所得Bi_2MoO_6微球由大量厚度约为20~50 nm的纳米片组成;沉淀-沉积法所得样品的形貌分析显示,尺寸约为10 nm的BiOBr量子点均匀沉积在Bi_2MoO_6微球表面,形成的新颖的BOB/BMO异质结.N2吸附/脱附结果表明,Bi_2MoO_6和BiOBr形成异质结具有大的比表面积(64.94 m2·g-1),且表面孔结构丰富.吸附/光催化降解实验结果表明,与纯Bi_2MoO_6或者BiOBr相比,BOB/BMO异质结表现出更好的吸附性能和光催化活性.吸附/光催化协同作用机理分析表明,BOB/BMO异质结具有大的比表面积和丰富的孔结构是其吸附性能增强的主要原因.此外,光致发光(PL)谱、光电流(PC)和交流阻抗(EIS)分析进一步揭示了BOB/BMO异质结有利于光生载流子的分离与转移,导致光催化活性增强,二者的协同作用使其对MO具有优越的去除性能.此外,BOB/BMO异质结较稳定,重复使用性能良好,有望用于MO废水的实际处理.     

抗生素药物诺氟沙星对锦鲤的毒性效应

为明确抗生素药物诺氟沙星对锦鲤的毒性效应,采用鱼类毒性试验方法,研究了诺氟沙星(Norfloxacin,NFLX)对锦鲤的急性毒性和亚急性毒性效应.结果表明,当NFLX暴露质量浓度达到1 000 mg/L时,NFLX对锦鲤无急性毒性.NFLK暴露15 d,在1 mg/L、5 mg/L、25mg/L和125 mg/L 4个组中,5 mg/L组锦鲤肝脏SOD活性在6d时达到最大(p＜0.01);125 mg./L组MDA含量在15 d时达到最大值(p＜0.01);25 mg/L、125 mg/L组锦鲤肝脏中MDA含量与暴露时间呈正相关,相关系数分别为0.938 1、0.953 5.各组GST活性和GSH质量比均受到不同程度的诱导,1 mg/L组NFLX可使鱼肝GST与GSH产生适应性反应;5 mg/L组诱导GST与GSH效应最为显著,呈现“钟形”变化趋势,5 mg/L很可能是NFLX对GST活性和GSH质量比影响的一个阈值或转折点.鱼肝GPT与GOT活性变化表现出一定的相似性,均呈现先升高后降低的变化规律,其中5 mg/L组被诱导效应最为显著(p＜0.01).5 mg/L很可能是锦鲤适应NFLX暴露和机体中生物酶发挥作用的一个转折点.比较上述抗氧化和转氨酶指标的敏感性和稳定性发现,在NFLX作用下,锦鲤肝脏中GST、GSH两个指标对NFLX的反应比SOD、MDA、GPT、GOT灵敏,变化规律稳定,更适合评价水环境中NFLX暴露的毒性效应.     

Review of the application of quantum dots in the heavy-metal detection

Heavy-metal contamination is a major concern, as excessive heavy metals produce environmental pollution, and the cumulative effects of heavy metals in vivo pose a major threat to human health. There is an urgent need for a rapid, sensitive, and efficient method for detecting heavy metals. Quantum dots (QDs) are in the category of semiconductor nanocrystals whose radii are less than or close to the exciton Bohr radius. QDs possess a potential in the biological and medical fields to function as a new type of fluorescent marker, because of their unique and tunable photophysical properties, which include broad excitation spectrum, narrow emission spectrum, tunable emission wavelengths, and negligible photobleaching. In recent years, QDs made significant progress in quantitative analysis by providing a new approach for determination of chemical content analysis. The aim of this study was to review the research progress of QD detection of heavy metals in water and consider the challenges and future outlook for QD-based sensors for heavy-metal ions.     

Photodegradation of sulfonamide antibiotics in simulated and natural sunlight: Implications for their environmental fate

The photochemical fate of seven sulfonamides was investigated in matrices representative of natural water bodies under various light sources. Fundamental photolysis parameters such as molar absorption coefficient, quantum yield (QY) and first-order rate constants were determined. The photolysis decay rate was dependent on the protonation state of the molecule, pH of the water sample and dissolved organic matter. Natural organic matter was the most significant factor in the indirect photolysis of sulfonamides. Half-lives were in the range of minutes at 254 nm to days under natural sunlight. Under natural sunlight, all sulfonamides showed higher removal rates in natural waters implying that indirect photolysis is the predominant mechanism.