Biosorption of Cr(III) from aqueous solution by freeze-dried activated sludge: Equilibrium,kinetic and thermodynamic studies

Batch biosorption experiments were conducted to remove Cr(III) from aqueous solutions using activated sludge from a sewage treatment plant. An investigation was conducted on the effects of the initial pH, contact time, temperature, and initial Cr(III) concentration in the biosorption process. The results revealed that the activated sludge exhibited the highest Cr(III) uptake capacity (120 mg·g⁻¹) at 45°C, initial pH of 4, and initial Cr(III) concentration of 100 mg·L⁻¹. The biosorption results obtained at various temperatures showed that the biosorption pattern accurately followed the Langmuir model. The calculated thermodynamic parameters, ΔG^o (−0.8– −4.58 kJ·mol⁻¹), ΔH^o (15.6–44.4 kJ·mol⁻¹), and ΔS^o (0.06–0.15 kJ·mol⁻¹·K⁻¹) clearly indicated that the biosorption process was feasible, spontaneous, endothermic, and physical. The pseudo first-order and second-order kinetic models were adopted to describe the experimental data, which revealed that the Cr(III) biosorption process conformed to the second-order rate expression and the biosorption rate constants decreased with increasing Cr(III) concentration. The analysis of the values of biosorption activation energy (E_a = −7 kJ·mol⁻¹) and the intra-particle diffusion model demonstrated that Cr(III) biosorption was film-diffusion-controlled.     

Development of pretreatment protocol for DNA extraction from biofilm attached to biologic activated carbon (BAC) granules

The biologic activated carbon (BAC) process is widely used in drinking water treatments. A comprehensive molecular analysis of the microbial community structure provides very helpful data to improve the reactor performance. However, the bottleneck of deoxyribonucleic acid (DNA) extraction from BAC attached biofilm has to be solved since the conventional procedure was unsuccessful due to firm biomass attachment and adsorption capacity of the BAC granules. In this study, five pretreatments were compared, and adding skim milk followed by ultrasonic vibration was proven to be the optimal choice. This protocol was further tested using the vertical BAC samples from the full-scale biofilter of Pinghu Water Plant. The results showed the DNA yielded a range of 40 μg·g^-1 BAC (dry weight) to over 100 μg·g^-1 BAC (dry weight), which were consistent with the biomass distribution. All results suggested that the final protocol could produce qualified genomic DNA as a template from the BAC filter for downstream molecular biology researches.     

岷江上游干旱河谷荒坡植物群落种-面积曲线拟合及最小面积确定

采用由3种曲线方程拟合的群落种-面积曲线来确定岷江上游干旱河谷荒坡植物群落的最小取样面积,结果表明:对于岷江上游干旱河谷荒坡植物群落类型而言,利用方程S=c-ae-bA拟合所得的种-面积曲线好于其他方程.当比例因子ρ取0.6、0.7、0.8时,群落最小面积均小于2 m2,样方可设置为1 m × 2 m,即样地面积为2 m2,能够满足精度60%～80%的研究要求;当ρ取0.9时,群落最小面积均明显小于4 m2,样方可设置为2 m × 2 m,即样地面积为4 m2,能够满足精度90%的研究要求.     

莱州湾南岸滨海湿地的生物多样性特征分析

通过2005年、2006年的实地调查和整理相关文献资料分析了莱州湾南岸滨海湿地的生物多样性总体特征,湿地维管束植物和水禽的区系组成特点,并与黄河三角洲滨海湿地的生物多样性特征进行了对比。莱州湾南岸滨海湿地维管束植物区系科的分化程度较低,属的分化程度较高,湿生植物、水生植物在区系中占据重要地位;从生活型角度分析,区系中草本植物、地下芽植物和一年生植物占据优势;从维管束植物区系的地理分布成分看,以温带分布属和世界分布属为主;莱州湾南岸滨海湿地水禽区系的居留型构成以旅鸟和候鸟为主,地理分布成分构成以古北界种为主。莱州湾南岸滨海湿地的维管束植物和水禽种类都明显少于相邻的黄河三角洲滨海湿地。     

冬季降雪过程对城市大气气态汞污染的影响

2009年降雪和非降雪期间对北京西北城区的气态总汞浓度进行了连续采样,比较了降雪期间、非降雪期间的气态总汞浓度日变化过程;降雪期间气态总汞浓度的降低和恢复过程。结果表明,降雪和非降雪期间大气气态总汞浓度的日均值有显著差异,降雪期间气态总汞的平均浓度为5．64ng·m^-3,非降雪期间的平均浓度为7．43ng·m^-3,前者约为后者的70％。降雪后约7h气态总汞浓度恢复到降雪前水平。研究中分析了气象因素（气压、风速、阵风速度、气温和相对湿度）对于气态总汞浓度的影响,结果表明：降雪期间主要受到风速（r=-0．527）和阵风速度（r=-0．574）的影响;非降雪期间主要受到风速（r=-0．691）,阵风速度（r=-0．726）和相对湿度（r=0．692）的影响,并且相对湿度的影响与风速的影响相近。降雪和非降雪期间气态总汞的日变化有所差异：非降雪期间气态总汞浓度在午夜和清晨较高,日变化趋势与相对湿度一致;降雪期间气态总汞的日变化没有明显规律。     

镉对花生苗期的毒害效应及其品种间差异

重金属在籽粒中的积累与植物对镉的生物学耐性和吸收特性有一定的内在联系。本研究通过比较不同花生（Arachis hypogaea L.）品种对镉胁迫的生物学耐性,旨在为进一步揭示花生籽粒镉积累的种内差异形成机制提供实验参数。在人工气候箱控制环境下的含镉的营养液砂培试验中,花生苗期对镉胁迫的反应具有显著的品种间遗传差异。基于植株生物量变化,可将花生的镉胁迫反应分为3种类型,即镉钝感型,品种有平度01、花育23和莱农13;敏感型,品种有中花4号、花育20、丰花3号、莱农29、豫花15和祁阳小籽;普通型,品种有湘农3010-w、湘农312、湘农55、丰花2号和湘农小果w2-7等。钝感型品种在5个加Cd水平下的茎叶干物量比对照平均降低22.8%,全株生物量平均降低11.7%;敏感型品种茎叶干物量平均降低38.0%,全株生物量降低29.2%;普通型品种茎叶干物量平均降低33.2%,全株生物量降低25.1%。随着Cd质量浓度提高和暴露时间延长,花生叶片的叶绿素质量分数显著降低,叶片和根系丙二醛质量分数及细胞膜透性显著提高,与钝感型品种相比,敏感型品种的上述生理指标变化速率较高,而且随着镉暴露时间延长,两者之间的差异性持续扩大。     

MnO2氧化去除制革污泥中的Cr(Ⅲ)

开展了MnO2化学氧化去除制革污泥中Cr(Ⅲ)的研究.结果表明,pH为4.0时MnO2处理污泥16h,Cr(Ⅲ)的溶出率达到90%以上(污泥中总Cr的原始浓度为6548mg·kg-1),但pH>6.0时MnO2基本不能去除污泥中的Cr(Ⅲ);处理温度升高、MnO2加入量的增大有利于Cr(Ⅲ)的去除.     

噻虫嗪在马铃薯中的残留分析

建立了噻虫嗪在马铃薯中的残留分析方法,并研究了其在马铃薯中的消解动态和最终残留.样品经甲醇超声提取、二氯甲烷液-液分配和Pesticarb/NH2SPE净化后,通过HPLC-UVD检测.该方法的添加回收率为80.5%—97.3%;变异系数为2.8%—9.8%;最小检出量为1.3×10-10g;最低检测浓度为0.01mg.kg-1.残留动态试验结果表明,噻虫嗪在马铃薯植株中的消解半衰期为1.83—1.92d.用药量56.25—84.375g(a.i.).ha-1,施药2—3次,施药后第1天马铃薯中噻虫嗪的残留量低于欧盟规定的MRL值(0.1mg.kg-1).     

Species and distribution of rare earth elements in the Baotou section of the Yellow River in China

This paper analyses the contents and species distributions of rare earth elements (REEs) in the water-suspended particulate-sediment system of the Baotou section of the Yellow River, China, with known anthropogenic REE input from industrial discharges. The major forms of REEs were suspended and dissolved in the mainstream and the tributaries of the Baotou section, respectively. The concentrations of the dissolved and suspended REEs had the same trends in the overlying water along the mainstream, which increased from the Seqi section (site A) to the mouth of the Sidaosha River (site D), reaching a maximum value at site D, and tending to decrease thereafter. The contents of REEs in sediment cores showed enrichment with light rare earth elements (LREEs). The bound to carbonates and to Fe–Mn oxides are the major forms of REE in the secondary phase and the REE exhibited LREE enrichment pattern and moderate Eu depletion in suspended particulates and surface sediments. The contents and species distributions of REEs in the water-suspended particulate-sediment system of the Baotou section suggest that the anthropogenic source of REEs from Baotou city have enhanced REE accumulation to the Baotou section. This information is important for predicting possible pollution resulting from anthropogenic REE input into rivers.     

不同油类对虾蟹类幼体的胁迫效应

了解不同油类对虾蟹类幼体的急性毒性效应。曝油处理采用磁力搅拌器搅拌,一定时间的超声波乳化等操作,模拟溢油在海洋中风浪、涡动、湍流的乳化过程;设置阶梯浓度组,并在多个平行组急性试验的基础上,估算出8种油品对2种虾类和2种蟹类的半致死质量浓度LC50和安全质量浓度MPC,并运用程序编制溢油质量浓度与虾蟹类死亡率相关性的估算模型。经过分析,结果得到：各MPC值参差不齐,差距较大;燃料油普遍比原油的毒性效应大;相同生长阶段,蟹类比虾类抗油毒害性强、中国明对虾Fenneropenaeuschinensis比日本囊对虾Marsupenaeusjaponicus抗油毒害性强、锯缘青蟹Scyllaserrata比三疣梭子蟹Portunustrituberculatu抗油毒害性强。编制的溢油质量浓度与死亡率相关性的评估模型,简易方便直观,为渔业污染事故理赔提供了一定的参考价值,亦为海域的生态经济学评估提供了一种新的研究方法。