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991.
Very polar oil compounds are predominant in the resulting water soluble fraction (WSF) of crude oil, in agreement with their high solubility in seawater. Non‐volatile hydrocarbons represent only a low proportion of total soluble extracts. The experimental process we have achieved allows us to obtain quantitative and reproducible soluble oil extracts that could be used in ecotoxicological tests and for the study and the characterization of marine oil pollution. 相似文献
992.
The synthesis of several 6‐n‐propyl‐5‐arylazo‐2‐thiouracil derivatives was achieved. The antithyroid activity of these derivatives has been determined using iodine‐125‐thiocyanate discharge technique in rats, and 6‐n‐propyl‐2‐thiouracil (PTU) as a standard. None of the 5‐arylazo‐2‐thiouracil analogs showed antithyroid activity as compared to PTU. The structure‐activity relationships (SAR) of position 5 in the PTU molecule and the requirements for better binding to the proposed receptor are discussed. 相似文献
993.
Zuhair R. Zahid Zuhair S. Al‐Hakkak Abdul Hussain H. Kadhim Elias A. Elias Iman S. Al‐Jumaily 《毒物与环境化学》2013,95(2-3):131-136
It has been repeatedly stressed that the biological effectiveness of chromium depends entirely on its oxidation state. The present work compares the histological effects of ingested trivalent and hexavalent chromium compounds on the mouse testes. The results showed comparable data of food consumption and gain in body weight. Both compounds produced ambiguous levels of degeneration in the outmost cellular layers of a number of seminiferous tubules, reduced the number of spermatogonia per tubule and the sperm count, and caused significant increases in the percentage of morphologically abnormal sperms. Generally, all these effects were more pronounced in animals which ingested the hexavalent chromium. 相似文献
994.
This study reports the dry deposition pollutants of anion species (NO3 ‐ and SO4 ‐2) in the Ping Tung City of Southern Taiwan. Several deposition properties are discussed in this paper. It included dry deposition flux, anion species size distribution and deposition velocities. Noll Rotary Impactor (NRI) and Microorifice Uniform Deposit Impactor (MOUDI) were used to collect ambient air coarse and fine particulate. Dry deposition plate was applied to collect particle deposition flux. Dionex 2000i/SP Ion Chromatography equipped with 4 mm AG4A‐SC and AS4A‐SC column was employed to analyze the anion species. The eluent solution is 1.8 mM sodium carbonate/1.7 mM sodium bicarbonate. The measured dry deposition flux of nitrate ranged from 0.63 to 3.96 mg/m2‐day and averaged 2.12 mg/m2‐day, while the measured dry deposition of sulfate ranged from 1.17 to 9.53 mg/m2‐day and averaged 3.92 mg/m2‐day. The particle size distribution of nitrate has bimodal particle size distributions. However, the sulfate displayed uniform particle size distribution for all four sampling sites. Mean cumulative fraction (F%) of nitrate in the particle size range below 1, 2.5, 10 and 25 μm, in sequence, were 34.6%, 60.9%, 91.0% and 97.6%, respectively. However, the mean F% of sulfate in the particle size range below 1, 2.5, 10 and 25 um, in sequence, were 57.3%, 82.6%, 90.3% and 98.0%, respectively. The sulfate has more F% in the submicron particles. The mean MMD o of nitrate and sulfate are 2.35 and 0.87 μm, respectively. The mean dry deposition velocities of nitrate and sulfate are 0.45 and 0.38 cm/sec, respectively. 相似文献
995.
Chronic inhalation of aerosols of different Cd compounds by rats gave sufficient evidence that inhaled Cd is a lung carcinogen in rats. In contrast, the evidence in humans has been termed limited that inhaled Cd causes lung cancer in occupationally exposed humans. In order to assess the carcinogenic potential of ambient air concentrations of Cd, the accumulated dose of Cd in lung tissue from a rat inhalation study was modelled taking into account deposition and retention of Cd in the lung. A lung Cd—cancer incidence relationship could then be established, and an equivalent human exposure could be calculated using man specific pulmonary Cd retention and deposition data for Cd containing particle sizes in the ambient air. Linear interpolation to low doses showed that the pulmonary carcinogenic risk from inhalation of environmental airborne Cd is generally very low, but may reach about 1 × 10‐4 in polluted industrialized areas. Combined exposures to Cd plus other carcinogens or air pollutants may increase the risk considerably. Cd in cigarette mainstream smoke was estimated to contribute less than 5 % of the total lung cancer risk from smoking cigarettes. However, the influence of co‐exposure to other compounds in cigarette smoke is not known and should be taken into account. 相似文献
996.
997.
This research work was performed to evaluate ozonation and granular activated carbon adsorption processes from the view‐point of controlling the formation of disinfection by products (DBPs). Both the humic acid and raw water were first preozonated and then adsorbed on the activated carbon to assess the potency for removal of total organic carbon (TOC) and DBPs. The disinfection by‐product including THMs and HAAs, in principle, can be successfully removed through a use of the ozonation and granular activated carbon (GAC) adsorption processes. However, in practice dealing with the raw water, it is necessary to introduce the pilot‐plant to obtain the design and operation guidelines for the water treatment plant through the ICA (Instrumentation Control and Automation) program in our future research work. 相似文献
998.
Trace analysis of airborne toluene diisocyanate (TDI) vapor was accomplished by measuring the derivative using gas chromatography with electron‐capture detector after collecting gas samples with a microimpinger containing 2 ml toluene, 1 μl pentafluorobenzyl alcohol, and 1 μl triethylamine. The sampling efficiency was determined to be 99.4% for short‐term exposure level of TDI and the 2,4‐ and 2,6‐isomers of TDI were well separated. The derivative was identified to be a new compound with a molecular weight of 570 by mass spectrometry in fast atomic bombardment mode and nuclear magnetic resonance spectrometry. This method is convenient and can be applied in the field where airborne TDI is in vapor form. 相似文献
999.
M. E. Alvarez Piñeiro M. A. Lage Yusty J. Simal Lozano S. T. Carril Gonzalez‐Barros 《毒物与环境化学》2013,95(1-4):31-36
PCB and PCT residues were measured in free‐living (FM) and cultivated mussels (CM) from ten sites in Galicia by gas chromatography with electron capture detector and capillary column. The level of PCB1260 and PCT5460 in FMs increases going from Muros‐Noya to Vigo estuarine bay. There was a trend of increase from north to south. 相似文献
1000.
Mohammad Rasheed Tariq Al Najjar Mohamad G. Al-Masri Saima Mian 《Chemistry and Ecology》2013,29(4):287-295
Degradation rates of light and heavy oil in permeable carbonate sands from the Gulf of Aqaba were investigated to evaluate the ability of sediments to degrade oil compounds. Silicate sands that are less permeable and different properties from carbonate sands were used for comparison. Estimates of oil degradation rates were based on oxygen consumption rates, calculated by incubating natural carbonate sands with oil. The degradation rates of light oil were twofold higher than those of heavy oil, which may be attributed to the presence of a higher carbon number in heavy oil compared with light oil. Degradation rates of light oil in carbonate sands were twofold higher than in silicate sands. Oil degradation rates calculated using the bottle incubation technique were three- to fourfold higher than rates from chamber incubations, indicating the importance of adequate mixing between oil particles and sediments during degradation processes. This study suggests that permeable sands, through their chemical and physical properties, increase oil biodegradation rates by enhancing flow through sediment particles and positively impacting bioturbation processes. 相似文献