离子注入法选育高效降解蒽的鞘氨醇单胞菌突变株

鞘氨醇单胞菌(Sphingomonas sp.)AN1及其原生质体经N⁺ 离子注入诱变处理 ,蒽的降解率分别提高了29.3%和36.2%,总变异率分别为80%～100%、60%～80% ,耐蒽浓度分别达到300mg/L、400mg/L ;突变株经15代遗传稳定性检测,有2株(AN815-3,AN315-5)的性状可稳定遗传 ,其降解率分别为73%,75%,诱变效果显著.     

生物表面活性剂茶皂素离子浮选去除废水中镉离子

对生物表面活性剂茶皂素作为离子浮选剂去除废水中镉离子的能力进行了研究,对影响去除率和富集比的物理因素(包括溶液初始pH值、C茶皂素CCd2+(摩尔比)、离子强度(NaCl和NaNO3))和动力学参数(包括浮选时间和通气量)进行了考察.C茶皂素CCd2+=2∶1,pH为6.0,通气量为0.15L·min-1时得到了最佳去除效果,去除率达到85.87%,Cd2+的富集比达到19.43;而在C茶皂素CCd2+=2∶1,pH为8.0,通气量0.15L·min-1时,Cd2+去除率达到70.97%,富集比高达32.17.随着溶液离子强度的增强,镉离子去除率和富集比显著降低.泡沫浓缩液中加碱回收Cd2+,回收率为79.62%.     

湿沉降离子平衡参数取值范围的计算

为保证湿沉降监测数据的可靠性及国际间数据的可比性,对不同类型湿沉降监测的离子平衡参数(R₁)的参考值X_R1的范围进行了计算和分析.结果表明,X_R1的取值主要受降水中离子组成、离子浓度以及监测准确性的影响.不同类型降水的X_R1的取值范围有所差别,同一类型降水的X_R1也会因降水中总离子浓度的差别而不同.降水中总离子浓度(C+A)>100μeq/L时,海陆相间型降水的X_R1的取值范围为5%～7%;内陆型降水的X_R1的取值范围为5%～9%;海洋型降水X_R1的取值范围为5%～11%.当(C+A)<50μeq/L时,总离子浓度越小,实验的精密度越差,离子浓度的精密度(ai)值越大.当ai取100%时,X_R1的取值范围为33%~71%.国际间同类降水监测规范比较,(C+A)≥50μeq/L时,_R1的取值基本在X_R1的计算范围内;而(C+A)<50μeq/L时,各个标准之间的差别较大.     

Potential application of 2-(6-ethylamino-3-ethylimino-2,7-dimethyl-3H-xanthen-9-yl) benzoic acid phenyl thiourea for mercury determination

Heavy metal contamination of the environment is a public health problem and research to develop new tools for monitoring the environmental impact of these elements is necessary. This study describes the preparation of a rhodamine-based probe 1 and its potential applications for detecting mercuric ion [Hg(II)] in samples from a nutrition media containing Salvinia auriculata. It was observed that an excess of probe 1 led to quenching in the fluorescence/absorption response, which was evidenced by a decrease in the signal when the stoichiometry differed from 1:1. Consequently, this probe is not suitable for quantitative analysis of Hg(II). Also, probe 1 reacts with methylmercury (MeHg) with different stoichiometry than that observed for Hg(II). These results indicate the potential application of probe 1 for qualitative detection of Hg(II) and MeHg in environmental samples.     

Effect of transition metal ions on photocatalytic activity of ZnO in bleaching of some dyes

The photocatalytic bleaching of some dyes (erythrosin-B, fast green FCF and eosin Y) was carried in the presence of semiconducting zinc oxide and was observed spectrophotometrically. The effects of various operating variables like pH, concentration of dyes, amount of semiconductor and light intensity on the efficiency of the reaction were also observed. Attempts have been made to study the effect of the addition of other metal ions (Fe²⁺, Ni²⁺, Ag⁺, Cu²⁺, Co²⁺, V²⁺ and Mn²⁺). All the added metal ions increase the reaction rate to some extent. It was also observed that Fe²⁺ is most effective in photobleaching of erythrosin-B, whereas V²⁺ is more effective in the cases of fast green FCF and eosin Y. A tentative mechanism has been proposed.     

铅锌尾矿中重金属在模拟酸雨淋溶下的浸出规律

重金属尾矿污染是世界性难题,污染水体、大气和土壤,对周边的生态环境和人体健康造成严重危害。在我国酸雨范围大且酸雨问题比较严重的背景下,探讨酸雨淋溶下尾矿中重金属的浸出规律将有利于加强我国重金属尾矿的污染控制和管理。采用湖南桃林铅锌尾矿库中的尾矿模拟酸雨条件进行淋溶实验,研究发现重金属Pb、Zn、Cu、Mn含量分别为1252.5,849.4,363.1,280.0mg/kg。其中,Pb、Zn主要以残渣态存在,分别占69.7%和53.8%;Cu主要以有机结合态存在,占67.0%;Mn主要以铁锰氧化态、有机结合态和残渣态存在,共占90.0%。在静态淋溶实验中,固液比越大、模拟酸雨pH值越小,重金属的浸出浓度越大。在动态淋溶实验中,Zn、Mn浸出浓度随时间呈现减小趋势,而Pb和Cu浸出浓度随时间先增大,后减小。     

低能离子诱变产表面活性剂的烃降解菌研究

为有效治理石油污染土壤,从长期遭受石油污染的土壤中筛选出一株烃降解菌8-11作为出发菌,利用低能N+注入烃降解菌进行诱变,在能量为20 keV、剂量为90×2.6×1013ions/cm2条件下筛选出一株高效烃降解菌——诱变菌23。原油摇瓶发酵实验表明诱变菌对原油的降解率达到74%;降解后原油的全烃气相色谱图显示,经过7 d的作用,原油中的正构烷烃完全降解。诱变菌23能够产生大量的生物表面活性物质,傅里叶红外光谱分析表明其产生的生物活性物质为糖脂类化合物,该糖脂类生物表面活性剂能使发酵液的表面张力从空白对照的56.1 mN/m降低为29.3 mN/m。研究表明诱变菌23具有较高的烃降解能力,能有效降低表面张力,具有较大的应用潜力。     

Biosorption effects of copper ions on Candida utilis under negative pressure cavitation

Under the optimal condition of copper ions adsorption on yeast,we found some different effects among static adsorption, shaking adsorption and negative pressure cavitation adsorption, and the methods of yeast with different pretreatments also affect adsorption of copper ions. At the same time, the change of intercellular pH before and after adsorption of copper with BCECF was studied. The copper distribution was located by using PhenGreen （dipotassium salt and diacetate）, and the surface of yeast was observed by an atomic force microscope. The results showed that negative pressure cavitation can improve bioadsorption capacity of copper ions on yeast. However, the yeasts＇ pretreatment has a higher effect on bioadsorption. It indicates that heavy metal bioadsorption on yeast has much relation with its cellular molecule basis. With the adsorping, the intercellular pH of yeast increased gradually and changed from acidity to alkalescence. These results may suggest that negative pressure cavitation can compel heavy metals to transfer from the cell surface into inside cell and make the surface of yeast coarse.     

Geochemical and biological controls on trace metal transport in an acid mine impacted watershed

Water samples collected in an acid mine impacted watershed indicated that the concentrations of dissolved trace metals were diurnally influenced by mineral saturation, which is controlled primarily by pH and water temperature. Measurements taken suggested that these variations only occur at sample locations immediately downstream from the confluence of acidic and alkaline waters. It is at these locations where initial mineral precipitation occurred and where subtle changes in solubility were most affected, increasing trace metal removal when both the rate of photosynthesis (influencing pH in headwaters) and water temperature were at a maximum. The role of iron photoreduction (increased midday production of ferrous iron) on overall Cu, Mn, and Zn transport was also evaluated, but found to be inconclusive. Iron photoreduction may however influence adsorption and/or coprecipitation of trace metals through associated changes in oxidation state, solubility, and mineralogy of various iron colloids, which are produced upon the neutralization of acidic, metal enriched water. Furthermore, measured values of copper and zinc were compared to relative USEPA chronic criterion for exposure to continuous concentration (CCC) of metals by the calculation of a “toxicity unit” (TU). It was found that average values of both copper and zinc only exceeded the CCC (TU>1) in the acid mine-impacted Leona Creek. In general, zinc toxicity decreased while copper toxicity increased downstream of the confluence of the mine impacted Leona Creek and background Lion Creek (sampled at Lake Aliso), indicating a significant source of zinc in upstream, non mine-impacted samples.     

Holly (Ilex Aquifolium L.) As Zinc and Cadmium Accumulative Indicator in Biogeochemical Prospecting

The results of previous investigations in mineralized and sterile areas of Tuscany (Italy) appeared to point out the special aptitude of holly (Ilex aquifolium L.) in concentrating cadmium and zinc. in the present paper this behaviour has been verified in a mineralized area of Lombardy (Northern Italy).

Samples of leaves, twigs and barks from holly trees were collected, and metal contents (Zn, Cd, and Pb) have been determined by differential pulse anodic stripping voltammetry (DPASV). for comparison, some samples of wood anemone (Anemone nemorosa L.) and soil were also analyzed.

The data obtained confirm a preferential cadmium and zinc accumulation by holly (up to 16 and 1400 μg g^-1 dry weight, respectively) also depending on different vegetal organs and vegetative stages of plants. Highest contents of lead have been recovered in the outer portion of bark.