Proposed mechanism for bacterial metabolism of polyacrylate

A possible aerobic degradative pathway for polyacrylate was examined with trimer (1,3,5-pentane tricarboxylic acid; PTCA)-utilizing bacteria. A few metabolic products from PTCA accumulated in culture filtrates and reaction mixtures of washed cells. Fraction A was detected as a main metabolite by high-performance liquid chromatography. A small amount of fraction B was concomitant with fraction A. Another fraction, C, was also detected. These compounds were suggested by liquid chromatography-mass spectrometry analyses to be 1,3,5-(1- or 2-pentene)tricarboxylic acid (fraction A or B) and 1,3,5-(2-oxopentane)tricarboxylic acid (fraction C). Fraction A was quickly further metabolized by washed cells, but fraction B was only gradually degraded. From these results, the metabolic pathway for polyacrylate is suggested to be quite similar to-oxidation for saturated fatty acids. The degradation of PTCA by washed cells was slower than that by growing cells and was inhibited by 5 mM NaN₃. This suggests that the metabolism is linked to a respiratory chain or energy-producing system of bacteria which can aerobically assimilate PTCA.Paper presented at the Bio/Environmentally Degradable Polymer Society—Second National Meeting, August 19–21, 1993, Chicago, Illinois.     

Determination of Cadmium and Lead in Different Cigarette Brands in Jordan

Cadmium (Cd) and lead (Pb) concentrations in different cigarette brands sold and/or produced in Jordan were determined by graphite furnace atomic absorption spectrometry (GF-AAS). Average levels of Cd and Pb in different cigarette brands in Jordan were 2.64 and 2.67 g g^{– 1} (DW), respectively. The results obtained in this study estimate the average quantity of Cd inhaled from smoking one packet of 20 cigarettes to be in the range of 3.65–7.30 g. Results suggest that the quantity of Pb inhaled of smoking one packet of 20 cigarettes, is estimated to be 0.74–2.22 g. The concentrations of Cd and Pb in cigarettes were significantly different between cigarette brands tested. Our results were compared with other worldwide studies.     

Lead Content of Petrol and Diesel and its Assessment in an Urban Environment

Pakistan is one of the few countries in Asia thatcontinues to use only leaded-petrol as vehicular fuel. Theconcentration of Pb in its petrol reported in 1991 was thehighest (1.5 – 2.0 g Pb L^-1) of all produced by the various Asiancountries and far exceeded the WHOs guideline of 0.15 g Pb L^-1. We have undertaken a study to trace and quantify this toxicelement in the environs of Karachi, Pakistans major metropolis,having more than 30% of the nations total number of vehicles.In this article we report the Pb contents of petrol and dieselcurrently manufactured and marketed in the city. Samples of`Regular petrol collected in 1999 was found to contain 0.363 gPb L^-1 (range: 0.335 – 0.390 g Pb L^-1), a factor of 5 lower than thatmarketed prior to 1991. Its concentration in diesel fuel was muchlower (0.017 g Pb L^-1). Based on the available statistical data onthe type and volume of vehicular traffic, we assessed that thecurrent lead emission from vehicular traffic into the atmosphereis 391 metric tons a year, which is a factor of 2.7 lower thanthat estimated for 1989.     

Metal Levels in Raccoon Tissues: Differences On and Off the Department of Energy's Savannah River Site in South Carolina

Levels of arsenic, cadmium, chromium, copper, lead, manganese, selenium, and strontium⁸⁸ were examined in heart, kidney, muscle, spleen and liver of raccoons (Procyon lotor) from four areas on the Department of Energy's Savannah River Site (SRS), including near a former reactor cooling reservoir and a coal ash basin, and from public hunting areas within 15 km of the site. Mercury is mentioned briefly because it is discussed more fully in another paper. We test the hypotheses that there are no differences in metal levels between raccoons on SRS and off the SRS (off-site), and among different locations on the SRS. Although raccoons collected off-site had significantly lower levels of mercury and selenium in both the liver and kidney, there were few consistencies otherwise. There were significantly higher levels of cadmium in liver of on-site compared to off-site raccoons, and significantly higher levels of chromium and strontium⁸⁸ in kidney of on-site compared to off-site raccoons. Copper and manganese were highest in the liver; cadmium, lead, mercury and selenium were highest in the liver and kidney; chromium was highest in the spleen and muscle; arsenic was highest in the heart, and strontium⁸⁸ was slightly higher in the kidney than other organs. Where there were significant differences on site, chromium, manganese were highest in raccoon tissues from Steel Creek; arsenic, lead and selenium were highest in the Ash Basin; cadmium was highest at Upper Three Runs; and strontium⁸⁸ was highest at Upper Three Runs and Steel Creek. The patterns were far from consistent.     

Distribution of heavy metals in sediment and water of river Gomti

Gomti river receives industrial as well as domestic wastes from various drains of Lucknow city. In the process the water and sediment of the river Gomti get contaminated with heavy metals and other pollutants. In the present study, impacts of domestic/industrial wastes on the water and sediment chemistry of river Gomti with special reference to heavy metals have been investigated in different seasons (summer, winter and rainy). For this, seven sampling sites: Gaughat, Mohan Meakin, Martyrs Memorial, Hanuman Setu, Nishatganj bridge, Pipraghat and Malhaur, in the river Gomti in Lucknow region were identified and samples of water and sediments were collected in all the three seasons. In the collected water and sediment samples, six metals (Cd, Cr, Cu, Ni, Pb, and Zn) were analyzed on ICP-AES (Inductively coupled plasma emission spectroscopy) Labtam Plasmalab 8440. High concentrations of all the metals were noticed in water and sediment in rainy season compared to summer and winter. Because in rainy season runoff from open contaminated sites, agricultural field and industries, directly comes into the river without any treatment. In both the cases, the concentration of zinc was maximum (0.091 g/ml in water and 182.13 g/g in sediment) and the concentration of cadmium (0.001 g/ml in water and 17.26 g/g in sediment) was minimum. Higher concentration of metal in water and sediment during rainy season could be due to the industrial/agricultural/domestic runoff coming into the river.     

激光散射法和便携式氢火焰离子化检测器法直读监测油烟排放

餐饮业油烟排放具有排放浓度不稳定、波动较大、排放时间短等特性，存在瞬时排放高值现象，油烟"看得见"和"闻得着"的问题依然存在，因此对油烟实现快速、及时、直读监测尤为必要。基于一种浓度可控且稳定的油烟产生技术，对直读激光散射法与经典手工称重法测定油烟颗粒物浓度值的数据线性关系进行了分析，发现2种方法数值的相关系数达0.99，通过直读修正激光散射法可以有效地测定油烟颗粒物浓度，并测定了不同水汽含量下油烟颗粒物排放情况，发现当相对湿度超过70%时，油烟颗粒物浓度测定值会发生突变。使用便携式氢火焰离子化检测器法（FID）和光离子化检测器法（PID）测定了不同油温下油烟中非甲烷总烃（NMHC）浓度，发现FID对油烟中NMHC的变化反应及时，能够较好地测定油烟中挥发性有机物的排放量。     

微波消解平台石墨炉原子吸收法测定活性污泥中重金属

以铜和铅为例建立了一种微波消解样品,平台石墨炉原子吸收法测定活性污泥中重金属含量的方法,该方法的样品加标回收率Cu为91 0%～97 3%,Pb为93 1%～98 0%,相对标准偏差RSD(%):Cu为1 38%～1 61%,Pb为1 28%～1 94%,检验限Cu为0 0052ng g,Pb为0 0073ng g,该方法应用于活性污泥中重金属的分析,实验所需时间短,取样量少,空白值低,实验过程中样品损失小,准确度和灵敏度高,结果令人满意。     

加载絮凝与PFS+PAM絮凝处理含氟废水对比试验研究

采用小试对配制的4种质量浓度(低、中低、中高和高质量浓度)含氟废水进行了加载絮凝与聚合硫酸铁(PFS)+聚丙烯酰胺(PAM)二段絮凝对比试验研究。根据对出水上清液的氟质量浓度、总铅质量浓度、浊度及污泥含水率的分析,综合评价了两种工艺处理性能。结果表明,加载絮凝工艺对4种质量浓度含氟废水的各项净水效能均优于PFS+PAM二段絮凝,且在相同PFS投加量下,加载絮凝工艺产生的污泥含水率更低。     

废弃菌糠资源化过程中的成分变化规律及其环境影响

针对废弃菌糠的循环利用工艺,选取杏鲍菇菌糠、平菇菌糠、菌糠有机肥等具有阶段代表性的样品,测定其营养组分、元素含量,分析菌糠在连续栽培和废弃菌糠堆肥处置过程中成分的变化,同时分析了菌糠/菌糠有机肥的重金属环境风险评估及淋溶状态下对环境可能的影响.结果表明,连续栽培后菌糠中水分下降13.8%,蛋白质、糖类则分别上升32.9%和20.4%,仍剩余大量营养物质;废菌糠堆肥后蛋白质、糖类分别下降50%和79%,木质素、纤维素、半纤维素无明显变化,C/N比下降,总腐殖酸量增加18.6%.通过重金属含量的测定,确定菌糠/菌糠有机肥中的As、Hg、Pb、Cd、Cr等重金属指标均低于我国《NY525-2012有机肥料》的限值标准.菌糠/菌糠有机肥所含氮、磷、有机物均有淋出趋势,其中有机肥的氮、有机物淋失累积量相比菌糠下降15.0%和62.8%.     

铅吸附深色有隔内生真菌的筛选及其吸附特性

本文通过测定沙门外瓶柄霉(Exophiala salmonis BC5)、甘瓶霉(Phialophora mustea BC42)、菊异茎点霉(Paraphoma chrysanthemicola B100)和枝状枝孢菌(Cladosporium cladosporioides B142)4种具有耐铅特性的深色有隔内生真菌(Dark Septate Endophytes,DSE)非活性菌丝的铅吸附能力,从中筛选出铅吸附能力强的菌种并研究其吸附特性.扫描电镜观察结果显示,4种DSE吸附剂均有管道状结构,以枝状枝孢菌的直径最大((4.04±0.68)μm),且较为完整,枝状枝孢菌吸附剂的表面比较粗糙,其余3种DSE吸附剂的表面均比较光滑;傅立叶红外光谱分析表明,4种DSE吸附剂均含有氨基(—NH2)、羟基(—OH)、酯羰基(—COO)和羧基(—COOH)等官能团;当吸附时间分别为15 min和60 min时,枝状枝孢菌对铅的去除率、吸附量分别达83.30%、14.73 mg·g~(-1)和94.86%、19.54 mg·g~(-1),均显著高于其他3种真菌,其次是菊异茎点霉,沙门外瓶柄霉和甘瓶霉的吸附能力较差.进一步研究枝状枝孢菌的铅吸附特性,结果表明:p H(2.0~6.0)、初始金属浓度(10~300μg·m L~(-1))、吸附时间(5~180 min)、吸附剂剂量(0.5~10 g·L~(-1))、温度(20~40℃)及转速(80~180 r·min-1)对枝状枝孢菌的铅吸附过程均有显著影响,最佳的吸附条件分别为p H 5.0、初始金属浓度150μg·m L~(-1)、吸附时间120 min、吸附剂剂量3 g·L~(-1)、温度25℃、转速180 r·min-1,此时吸附量为40.8 mg·g~(-1).