Immobilization of an enzyme from a Fusarium fungus WZ-I for chlorpyrifos degradation

The free enzyme extracted from WZ-I,which was identified as Fusarium LK.ex Fx,could effectively degrade chlorpyrifos,an organophosphate insecticide.The methods of immobilizing this free enzyme and determined its degradation-related characteristics were investigated.The properties of the immobilized enzyme were compared with those of the free enzyme.The optimal immobilization of the enzyme was achieved in a solution of 30 g/L sodium alginate at 4°C for 4-12 hr.The immobilized enzyme showed the maximal activity at pH 8.0,45°C.The maximum initial rate and the substrate concentration of the immobilized enzyme were less than that of the free enzyme.The immobilized enzyme,therefore,had a higher capacity to withstand a broader range of temperatures and pH conditions than the free enzyme.With varying pH and temperatures,the immobilized enzyme was more active than the free enzyme in the degradation reaction.In addition,the immobilized enzyme exhibited only a slight loss in its initial activity,even after three repeated uses.The results showed that the immobilized enzyme was more resistant to different environmental conditions,suggesting that it was viable for future practical use.     

Interaction of humic substances and hematite: FTIR study

IntroductionInteractionsofhumicsubstances(HSs)andironoxidesareofgreatsignificanceinmanygeochemicalprocesses.ItisclearthatadsorptionofHSstothesurfaceofironoxidescangreatlyinfluencethepropertiesofsuchsurfaces,thuspotentialaffectthefate,behavior,transportandtransformationofenvironmentalpollutants(Mcknight,1992).Ononehand,whenadsorbedtosurfacesofironoxides,HSsmaybindandhenceimmobilizetracemetals,radionucilides,andnonionicorganicpollutants,andtheyalsoalteroxidesurfacechargepropertiesandflocculat…     

养殖场周边环境污染对畜禽养殖质量影响研究——以基于DNA条形码技术的黄牛肉质检测物研究为例

当前养殖场周边环境严重影响畜禽类的养殖质量,以基于DNA条形码技术的黄牛肉质检测物研究为例,对黄牛肉的真伪进行了检测。对黄牛种类特异性基因COI基因(NC_006853.1)序列进行设计,利用DNA提取、DNA纯度和浓度测定、PCR扩增、电泳检测、DNA纯化和回收、DNA克隆,完成肉质真伪的检测。得到电泳检测结果,真正黄牛肉扩增片段长度为534 bp,其余肉品样本不能扩增出534 bp。实验结果表明,该检测方法操作方便,检测时间短,应用前景较好,可以满足市场肉类监督检测需要。     

饮用水处理中活性炭吸附卤乙酸的特性

采用静态和动态试验研究了活性炭对卤乙酸的物理吸附特性。静态试验表明：在单吸附质条件下,二氯乙酸和三氯乙酸的吸附等温线在低浓度区（Ｃｅ〈５０μｇ／Ｌ）表现为单层吸附,在高浓度区表现为多层吸附。活性炭对三氯乙酸的吸附能力高于二氯乙酸。在饮用水处理常见的浓度范围内,活性炭对三氯乙酸的吸附容量约为二氯乙酸的２倍。在多吸附质条件下,对三氯乙酸的吸附容量只略的降低,对二氯乙酸的吸附容量则显著下降,这与有机物的     

序批式移动床生物膜反应器内同步短程硝化反硝化的控制

在序批式移动床生物膜反应器(SBMBBR)内,对进水COD较低的条件下,模拟生活污水的亚硝化及脱氮性能进行了研究.结果表明,缺氧时间、进水COD、NH44 -N浓度、pH值以及溶解氧对亚硝化过程有明显影响.在进水COD为100mg·L-1NH4 4-N浓度为50mg·L-1时,调控溶解氧、pH,出水的亚硝化率可到99.7%,总氮去除率可达66.4%,表明系统中发生了同步短程硝化反硝化.     

CO3O4/介孔分子筛催化剂对苯催化完全氧化的研究

分别以介孔分子筛MCM-41、MCM-48、SBA-15为载体,采用等体积浸渍法制备了氧化钴/介孔分子筛催化剂,利用N2吸附、X射线衍射、程序升温还原等技术对催化剂进行了表征,考察了Co3O4的负载量及载体的孔结构对催化剂完全催化氧化苯的性能的影响.结果表明,Co3O4的负载量为20%时,催化剂的催化活性最好;载体的孔径和催化剂的可还原性能是影响催化活性的主要因素,催化剂活性顺序为Co3O4/SBA-15>Co3O4/MCM-41>Co3O4/MCM-48.     

人工湿地在冬季低温地区的应用研究进展

人工湿地运行效果受季节、温度等因素影响较大,在冬季低温地区运行效率下降,特别是N、P污染物去除率偏低,限制了其在冬季低温地区的推广应用.结合目前国内外人工湿地在冬季低温地区的应用情况,分析了影响人工湿地低温运行的因素,并对提高人工湿地在冬季低温地区运行效率的各种强化措施进行了总结.     

Optimizing the configuration of a clearwell by integrating pilot and full-scale tracer testing

In this paper, the main factors impacting the plug flow pattern of a clearwell were investigated by integrating pilot-scale, full-scale clearwell tracer testing and computational fluid dynamics (CFD) simulation. It was found that pilot tracer testing, full-scale tracer testing and CFD simulation all demonstrated that the correlation between the ratio of t ₁₀/T and L/W can be approximately expressed by: t ₁₀/T = 0.189 4ln(L/W)-0.049 4. This study confirmed that the installation of baffles within clearwells is an efficient way to optimize their configuration. In addition, the inlet velocity has a minimal contribution to the ratio of t ₁₀/T. However, the ratio of turning channel width to channel width (d/W) significantly contributes to the ratio of t ₁₀/T. The optimal ratio of d/W is 0.8–1.2 for maintaining better plug flow pattern. The number of turning channels is one of the main factors that impact the ratio of t ₁₀/T. When increasing the number of turning channels, a lower ratio of t ₁₀/T is obtained.     

气相分子吸收光谱法在海水无机氮测定中的适用性研究

为探究气相分子吸收光谱法在海水无机氮测定中的适用情况,在检出限的10～20倍、30～50倍、50～100倍3个浓度范围内开展了准确度、加标回收率和方法比对试验。结果表明,采用气相分子吸收光谱法测定海水亚硝酸盐氮(0～0.100 mg/L)、硝酸盐氮(0～0.400 mg/L)、氨氮(0～0.200 mg/L)时,标准曲线均具有很好的线性,线性拟合度均在0.999 3以上,检出限依次为0.000 8、0.004、0.004 mg/L,且该方法不具有盐效应,适用于海水样品的检测。当样品浓度太低时,气相分子吸收光谱法测定结果的准确度较低,因此,建议仅在亚硝酸盐氮浓度高于0.030 mg/L、硝酸盐氮浓度高于0.100 mg/L、氨氮浓度高于0.090 mg/L时使用该方法,对应的海域为河口及近岸等无机氮含量较高的海域。此外,为保证测定结果的准确度,每个样品需平行测定2～3次。     

Water quality of a tributary of the Pearl River, the Beijiang, Southern China: implications from multivariate statistical analyses

Water quality information of Beijiang River, a tributary of Pearl River in Guangdong, China, was analyzed to provide an overview of the hydrochemical functioning of a major agricultural/rural area and an industrial/urban area. Eighteen water quality parameters were surveyed at 13 sites from 2005 to 2006 on a monthly basis. A bivariate correlation analysis was carried out to evaluate the regional correlations of the water quality parameters, while the principal component analysis (PCA) technique was used to extract the most influential variables for regional variations of river water quality. Six principal components were extracted in PCA which explained more than 78% and 84% of the total variance for agricultural/rural and industrial/urban areas, respectively. Physicochemical factor, organic pollution, sewage pollution, geogenic factor, agricultural nonpoint source pollution, and accumulated pesticide usage were identified as potential pollution sources for agricultural/rural area, whereas industrial wastewaters pollution, mineral pollution, geogenic factor, urban sewage pollution, chemical industrial pollution, and water traffic pollution were the latent pollution sources for industrial/urban area. A multivariate linear regression of absolute principal component scores (MLR-APCS) technique was used to estimate contributions of all identified pollution sources to each water quality parameter. High coefficients of determination of the regression equations suggested that the MLR-APCS model was applicable for estimation of sources of most water quality parameters in the Beijiang River Basin.