Preparation of high resolution chromosomes from amniotic fluid cells

A relatively simple method of obtaining high resolution chromosomes from amniotic fluid cells is described. The elongated chromosomes are achieved by adding ethidium bromide (5μg/ml) to the culture 4 1/2 hours before harvesting and the high resolution banding can be produced by usual banding procedures.     

Water quality of the King Abdullah Canal/Jordan–impact on eutrophication and water disinfection

The King Abdullah Canal (KAC) is an artificial water conveyor serving as raw water source for drinking water supply of Amman and for irrigation purposes in the Jordan Valley. The main water sources for KAC originate from the Yarmouk River, the Mukheiba Wells, and the Peace Conveyor. Water samples were collected from December 2002 to May 2004 to investigate changes in physicochemical parameters and parameters related to eutrophication along KAC. The catchment area of KAC is highly heterogeneous in terms of topography, climate, geologic conditions, and land use, resulting in great variations in the physicochemical composition of the canal water. The Yarmouk River and the Mukheiba Wells reflect the water quality of precipitation without much dissolution of halides, whereas the Peace Conveyor shows a groundwater characteristic. Main dischargers of N and P compounds are the Yarmouk River, and dams and wadis along KAC. The concentrations in the canal are mostly above eutrophication level for N and P. Along KAC there is an increase in chlorophyll a concentration and plankton counts. The formation potentials for trihalomethanes (THMs) and for integrated organically bound halogens are determined by chlorination to evaluate the consequences of water disinfection. Due to relatively high bromide concentration mainly brominated THMs are formed.     

In vitro methylation of DNA by the fumigant methyl bromide

Abstract

Investigations have shown that the physical state of the DNA strongly influences the pattern of methylation observed when DNA or a substance containing DNA is treated with the fumigant methyl bromide. 1‐Methyl‐adenine and 7‐methylguanine were identified, after hydrolysis, as the major methylated bases of DNA which had been treated in the solid state. 3‐Methylcytosine, 3‐methyladenine and 7‐methyladenine were found as minor products. The overall methylation pattern was similar to that observed earlier for DNA of maize and wheat which had been fumigated. In contrast, when buffer solutions of DNA were treated with methyl bromide, the N‐7 position of guanine was the major site and the N‐3 position of adenine was the second most important site of methylation. This result corresponds to that previously observed in similar studies with buffer solutions of DNA and other methylating agents.     

Impact of biofumigation with solarization on degradation of pesticides and heavy metal accumulation

A greenhouse study was conducted to evaluate the effect of biofumigation (with sheep and chicken manure) combined with solarization on the dissipation of pesticides (pyrifenox, DDT and dieldrin), and on soil metals accumulation. The treatments consisted of a control, and soil disinfestations by biofumigation combined with solarization (B+S) for two, four, five, six consecutive years. B+S enhanced the dissipation of pyrifenox with regard to control treatment. Significant differences were not detected among plots disinfected with B+S for consecutive years. On the other hand, B+S had no effect on the dissipation of DDT and dieldrin, probably due to the resistance of these pesticides to microbial degradation and/or high temperatures. Biofumigation is considered to be an environmentally safe practice, since no accumulation of heavy metals such as Cd, Co, Cu, Cr, Pb, Ni, or Zn was observed after the subsequent application of organic matter through the treatments.     

羟基氧化铁催化臭氧氧化对滤后水卤乙酸生成势的影响

考察了滤后水经过单独臭氧氧化和羟基氧化铁(FeOOH)催化臭氧氧化后5种卤乙酸生成势(HAA5FP)的生成情况.研究了氧化时间、溴离子浓度、滤后水pH值、碱度和O3投量对2种氧化方式下HAA5FP的影响规律.发现该滤后水氯化后的HAA种类为二氯乙酸(DCAA)、三氯乙酸(TCAA)及溴离子存在时有二溴乙酸(DBAA).无溴离子存在时,催化臭氧氧化在5～20min内使得HAA5FP比臭氧氧化后的降低9.5%～18.3%.溴离子浓度增加使HAA5FP减少,催化臭氧氧化后HAA5FP也比臭氧氧化后低更多.中性pH时,催化臭氧氧化比臭氧氧化有更明显的控制HAA5FP的优势.重碳酸盐碱度升高使HAA5FP降低,且2种氧化后HAA5FP的差别减小.O₃/TOC比值为0.45～1.43的臭氧投量范围内,催化臭氧氧化后HAA5FP比臭氧氧化后减少11.2%～28.0%.催化臭氧氧化对滤后水HAA5FP的影响与FeOOH催化臭氧生成羟基自由基的特点密切相关.     

氨基黑10B褪色光度法测定痕量季铵盐型阳离子表面活性剂的研究

研究了在硫酸介质中,季铵盐型表面活性剂溴化十六烷基三甲基铵(CTMAB)、溴化十六烷基吡啶(CPB)对氨基黑10B的褪色作用,建立了褪色光度法测定痕量CTMAB和CPB的新方法,并探讨了褪色反应的机理和条件,测定CTMAB和CPB的线性范围皆为0～3×10-5mol L,摩尔吸光系数分别为1 77×104L mol·cm和1 17×104L mol·cm,用于水样中微量季铵盐型表面活性剂的测定,结果满意。     

溴化十四烷基吡啶增强固定土壤中萘及其机理

用吸附平衡法,研究了溴化十四烷基吡啶(MPB)存在下,萘在4种土壤上的吸附行为及其机理,为表面活性剂在污染土壤修复中的应用提供理论参考.结果表明,当MPB的平衡浓度(X)小于1倍临界胶束浓度(CMC)时,萘的表观分配系数(K_d*)随MPB加入量的增大而急剧增大;当X>1CMC时,增加的MPB对萘主要起胶束增溶作用,K_d*值则随MPB浓度增加而急剧下降,而后趋于缓和,1/K_d*与X呈线性关系;当X约为1CMC时,K_d*在4种土壤上达到最大值(K_d*max),分别为112.5,170.8,406.8,190.5mL/g,与MPB的饱和吸附量(Qo)成正比;K_d*max/K_d比值则分别为20.49,16.86,20.60,5.30,与土壤的foc成反比.     

阴-阳离子有机膨润土制备及其对铅离子的吸附

用十八烷基三甲基溴化铵（STAB）和十二烷基苯磺酸钠（SDBS）共同改性膨润土制备阴．阳离子有机膨润土，并用红外光谱分析法、热分析法和X粉晶衍射分析进行了表征；考察了阴-阳离子有机膨润土对铅离子的吸附性能。结果表明，用0．5CEC（cationexchangecapacity）十八烷基三甲基溴化铵和0．4CEC十二烷基苯磺酸钠改性的膨润土吸附铅的效果最佳；阴-阳离子有机膨润土吸附铅离子的能力比改性前明显增加，达到吸附平衡所需要的时间缩短；pH值强烈影响有机膨润土对铅离子吸附；有机膨润土对铅离子等温吸附过程符合Langmuir吸附模型；吸附热力学分析表明该吸附是一个放热过程，降低温度有利于铅离子的吸附。     

Influence of the organic complex concentration on adsorption of herbicide in organic modified montmorillonite

This study was undertaken to determine the impact of the organic complex concentration on the adsorption of herbicide (acetochlor) at the surface of the organic modified montmorillonite. In this work, natural montmorillonite from Bogovina (Boljevac municipality, Serbia) was used for organic modification. Cation-exchange capacity of this montmorillonite was determined using a methylene blue method (86 mmol/100 g of clay). Montmorillonite has been modified first with NaCl and then with hexadecyltrimethylammonium bromide (HDTMA-bromide) organic complex. Saturation of cation exchange capacity (CEC) was 50%, 100%, and 150%. Changes in the properties of the inorganic and organic montmorillonite have been examined using the X-ray diffraction, Fourier transform infrared spectroscopy, and batch equilibrium method. Montmorillonite modified with HDTMA-bromide demonstrated higher uptake of the herbicide, compared to the inorganic montmorillonite. Comparing the values Freundlich coefficients in batch equilibrium method, it can be seen that the adsorption of acetochlor decreased in the series: 0.5 CEC HM > 1 CEC HM > 1.5 CEC HM > NaM.     

溴化十四烷基吡啶对黑麦草吸收土壤中菲的影响

研究了澳化十四烷基吡啶(Myrlstylpyridinium bromide,MPB)对黑麦草吸收土壤中菲的影响.结果表明.由于MPB能显著增强吸附固定土壤中的菲,限制其从土壤固相向土壤水相迁移,从而可降低土壤水相中菲浓度,导致黑麦草吸收积累菲的程度降低.在两种不同菲污染水平的土壤中,MPB添加浓度为0～600 mg·kg-1时,黑麦草根系和茎叶中菲含量均随MPB添加量的增加而降低.当MPB添加浓度为600 mg·kg-1时.黑麦草根系菲含量分别为0.12 mg·kg-1和0.35 mg·kg-1,分别比对照低了77.0%和53.3%;茎叶中菲含量为0.12 mg·kg-1和0.26 mg·kg-1,分别比对照低了64.7%和50.9%.