奇异的死亡谷

2005年暑假,我们一家三人游览了美国西部的死亡谷。死亡谷位于加利福尼亚、内华达和犹他三州交界的大沙漠中,呈椭圆形,高山环伺,南北长约300公里,东西宽约20公里,是一个巨大的地理博物馆,各     

Copper recovery from leach solution of waste printed circuit boards by pulse current electrodeposition

Journal of Material Cycles and Waste Management - The copper recovery from waste printed circuit boards is of great significance to protect natural resource and environment. Direct current...     

表面活性剂强化超滤法处理亚甲基蓝废水

采用无机陶瓷超滤膜和低浓度阴离子表面活性剂十二烷基苯磺酸钠(SDBS)处理亚甲基蓝(MB)模拟废水,考察了废水中SDBS、MB浓度及废水pH对超滤过程的影响.实验结果表明:SDBS浓度影响MB在最大吸收波长处的吸光度值;当废水中SDBS浓度为1.20 mmol/L(即25℃时的临界胶束浓度)、废水中MB浓度为1.00 mmol/L、废水pH为9.0时,超滤效果最好;在此条件下,透过液中SDBS浓度和MB浓度分别为0.06 mmoL/L和0.01 mmol/L,MB的截留率为99.2%,膜通量为309.6 L/(m~2·h).SDBS对MB超滤过程的强化机理主要为MB与SDBS形成结合体析出及SDBS胶束的增溶作用.     

Competitive biodegradation of dichlobenil and atrazine coexisting in soil amended with a char and citrate

The role of char nutrients in the biodegradation of coexisting dichlobenil and atrazine in a soil by their respective bacterial degraders, DDN and ADP, was evaluated. Under growing conditions, their degradation in soil extract was slow with <40% and <20% degraded within 64 h, respectively. The degradation in extracts and slurries of char-amended solids increased with increasing char content, due to nutritional stimulation on microbial activities. By supplementing soil extract with various major nutrients, the measured degradation demonstrated that P was the exclusive limiting nutrient. The reduction in the degradation of coexisting dichlobenil and atrazine resulted apparently from the competitive utilization of P by DDN and ADP. With a shorter lag phase, ADP commenced growing earlier than DDN with the advantage of utilizing P first in insufficient supply. This resulted in an inhibition on the growth of DDN and thus suppression on dichlobenil degradation.     

汞胁迫对小麦幼苗抗氧化酶活性的影响

通过营养液培养实验,研究了小麦幼苗在遭受汞胁迫后,地上部及根系抗氧化酶活性的变化．试验表明:小麦幼苗受到汞胁迫后,地上部及根系的超氧化物歧化酶(ＳＯＤ)的活性均显著增加,过氧化氢酶(ＣＡＴ) 的活性也比对照有所增强,但不如ＳＯＤ酶变化迅速,表明ＳＯＤ酶活性是小麦幼苗遭受汞胁迫时比较敏感的生物标记物．但是,小麦幼苗地上部及根系的丙二醛(ＭＤＡ) 含量仍均比对照显著升高,表明小麦幼苗的膜系统受到了一定程度的破坏．试验同时还反映出,汞胁迫对小麦幼苗根系的影响强于对地上部的影响．     

Estimation of septic tank setback distances based on transport of E. coli and F-RNA phages

Setback distances between septic tank systems and the shorelines of Lake Okareka, New Zealand were determined from model simulations for a worst-case scenario, using the highest hydraulic conductivity and gradient measured in the field, removal rates of the microbial indicators (Escherichia coli and F-RNA phages) determined from a column experiment, and maximum values of the design criteria for the disposal system, and assuming an absence of an unsaturated zone, a continuous discharge of the raw effluent from a failed or non-complying treatment system (both indicators at concentrations of 1x10(7) counts/100 ml) into the groundwater and no sorption of pathogens in the aquifer. Modelling results suggest that the minimal setback distances were 16 m to satisfy the New Zealand Recreational Water Quality Guidelines for E. coli <126 per 100 ml (Ministry for the Environment, 1999) and 48 m to meet the Drinking-Water Standards for New Zealand 2000 for enteric virus <1 per 100 l (Ministry of Health, 2000). These distances may be applicable for other lakeshores in pumice sand aquifers with groundwater velocities <7 m/day. Findings of laboratory column and batch experiments provided an insight into the microbial attenuation and transport processes in pumice sand aquifers. Bacterial removal was predominately through filtration (87-88%) and partially by die-off (12-13%), while viral removal was by both die-off (45%) and filtration (55%). In addition, microbial die-off in groundwater without aquifer material (i.e., free microbes) was much lower than die-off in groundwater with aquifer material (i.e., sorbed microbes) and contributed only 2-6% to the total removal. This implies that the setback distances estimated from die-off rates for the free microbes, determined in the laboratory without considering aquifer media and other removal processes, which are often reported in the literature, could be larger than necessary.     

中国降水量高度效应及全球升温对它的影响

利用中国气象中心160站点的实际观察资料,对中国半个世纪的降水变化进行了系统分析,发现中国的夏季降水量与海拔高度存在着很好的反相关关系;同时,全球升温使得降水量的高度效应增强,主要表现为高海拔降水量海拔效应明显增强,这主要是由全球升温引起环流系统增强所引起的.     

二级UASB厌氧工艺在制药废水中的应用

抗菌素制药污水复杂,其CODCr高达39000mgL,硫酸盐的浓度在6500mgL左右,常规工艺很难处理,山东某制药厂采用了二级厌氧工艺处理此类废水,取得了良好的处理效果和经济效益。     

基于Kaya方法的四个直辖市碳效率评价与比较

应用Kaya恒等式的计算方法对我国4个直辖市2005-2009年的碳效率进行了评价和比较分析,结果显示:4个直辖市碳效率的排序在2005-2009年间没有发生变化,4个城市的碳效率都处于上升态势。