Advanced Materials Research Vols. 356-360

Abstract: In order to forecast the occurrence of red tide in the ocean, it is necessary to observe the state of algae reproduction in seawater. A method was proposed for forecasting the state of algae reproduction indirectly by modeling to predict the concentration of chlorophyll-a. Data-driven learning algorithm of fuzzy nearest neighbor clustering was used for pretreatment of sampling data. State prediction model for concentration of chlorophyll-a in seawater was built based on the optimal fuzzy logic system. Considering the character of sampling data and the demand of decreasing the rank of the model, a kind of improved learning algorithm of fuzzy nearest neighbor clustering was designed, and it was used in the state prediction for concentration of chlorophyll-a. The experiment indicates that the improved method can effectively extract the character of sampling data, reduce the dimension of the data, and improve the convergence speed of algorithm learning. The improved fuzzy nearest neighbor clustering algorithm reduces the complexity of modeling for prediction, and this kind of model has fine performance of generalization. It can effectively predict the state of algae reproduction in seawater.

Abstract: Self-combustion of oil shale has been occurring and widespread in a long term while oil shale was considerably piled in Fushun dumping sites. After collecting samples of high- and low-grade oil shale from Fushun West Open Mine, the self-combusted oil shale from Fushun West Dumping Site, and designing the indoor high-temperature incineration experiments to simulate the self- combustion process, we tested trace elements in them and their ashes of 700°C, 1000°C by means of ICP-MS. Based on the analysis and comparison of the test dada, we studied content characteristics and migration pattern of elements during self-combustion. The results showed that elements were distributed in the similar way in samples and contents of Zr, Sr, Cr, V, Zn, Ni, Rb and Li were very high. A large amounts of trace elements were found to enter the atmosphere through volatilization in the process of Self-combustion, especially those higher volatile elements, such as Sb, Zn, Pb, W, Sn, Ta and Cd, while a few elements preferred to concentrate in solid-phase ashes. Different distribution and migration capacities of elements might be the main reason for the higher concentration of some elements in self-combusted oil shale than their background values in Liaoning soil.

Abstract: A method for determination of Chromium(VI) by reversed flow injection spectrophotometry based on the catalytic effects of chromium on the oxidation reaction of methylene blue by sodium periodate in sulfuric acid medium is established. Effects of concentration of reagents and other conditions have been optimized. Calibration graphs are linear for ranges of 0 to 1.0mgl⁻¹. A detection limit of 0.007mgl⁻¹ chromium is achieved. The proposed method is successfully applied to the analyses of industrial waste water and electroplating waste liquor, with relative standard deviation of less than 1.5% and the recoveries are 92.9％ to 97.5％for the determination of chromium.

Abstract: Different soluble inorganic salts were irrigated into batches of soil samples by setting contrastive experiments on the basis of Tessier sequential extraction procedure to study their influences upon Cd forms in the soil. Research shows that all the three salts were able to influence the forms of Cd in the soil: NaCl and Na₂SO₄ added into the soil could increase the contents of exchangeable Cd and the higher the concentration, the greater the impact, while Na₂CO₃ could decrease it by 30.35%(4 g/kg Na₂CO₃ added) and 69.87%(8 g/kg Na2CO3 added). Carbonate content of Cd was influenced obviously by NaCl, with the decrease of 7.30%, 10.52% corresponding to low concentration and high concentration of NaCl, and Na₂CO₃ can increase this form slightly, Na₂SO₄ had little effect, so the content remained unchanged. The Fe-Mn oxidation form of Cd remained the original level when NaCl was added in the samples while it increased with the addition of Na₂CO₃ obviously and the concentration increased 8.67% (4 g/kg Na₂CO₃ added) and 51.85% (8 g/kg Na₂CO₃ added),but it decreased by the effect of Na₂SO₄. Organic Cd and the residual Cd fluctuated slightly at a very low concentration. The total Cd decreased with the addition of sodium salt.

Abstract: A simple, rapid, sensitive and high-efficiency method for determ-ination of odorous compounds such as 2-methylisobomeol (2-MIB) and trans-1,10-dimethyl-trans-9-decalol (Geosmin) in the source of drinking water was developed by solid-phase microe- xtraction(SPME) followed by gas chromatography-mass spectrometry(GC-MS). In this study, various of SPME conditions have been optimized in detail. The results show that DVB/CAR/ PDMS fiber was found to possess the best extraction efficiency for the odorous compounds in water. SPME was carried out by using 25mL samples, addition of 6 g NaCl, stirring at 1150 rpm and temperature at 80°C for 15 min to enrich the target analytes. After that, the fiber was desorbed at 250°C for 2min and determined by GC-MS. 2-MIB and GSM were separated within 15 min using a HP-5MS capillary column and detected in the selective ion monitoring mode. The optimized method has been proved with excellent linearity and precision. Using this method, the calibration curves of 2-MIB and GSM were linear in the range of 10-500 ng/L, and the correlation coefficients were both above 0.9984. The detection limits (S/N=3) of 2-MIB and GSM were 1.2 and 0.9 ng/L, respectively. The optimized SPME was proved to be a very practical method for determination of the trace odorous compounds in the source of drinking water and applied with satisfactory results.

Abstract: The microcystins (MCs) were released by alge cells rupture when cyanobacterial blooms occur in eutrophic freshwater body. MCs are toxic, which have been considered as potential tumor promoters. MCs usually exist in water by the level of ng/L - μg/L. In this paper, the pre-treatment techniques for determinating the trace MCs, including solid-phase extraction (SPE), solid-phase microextraction (SPME), immune affinity chromatography (IAC), cloud point extraction (CPE) are summarized. The advantages and disadvantages of each technique are presented. Chromatography analysis methods are also reviewed.

Abstract: Based on the Jihogntan reservoir’s monitoring data from 2006 to 2009, eutrophication of Jihongtan reservoir was assessed. The result showed that the nutrition level of the Jihongtan reservoir was middle in recent years. The average concentration of chlorophyll-a(Chla) was higher in summer and autumn than in spring and winter. The correlation between concentration of Chla and some environmental factors was studied by statistical method, and seasonal variation of Chla and the extent of eutrophication were also analyzed. The results showed that the correlations between Chla and total nitrogen(TN), dissolved oxygen(DO) and transparency were significantly negative, and that between Chla and total phosphorus(TP), temperature(T) and potassium permanganate index(COD _Mn) were significantly positive. The growth of phytoplankton was promoted by TP and TN at low concentrations, and inhibited by TN at high concentrations.

Abstract: To understand the effects of environmental factors, such as the light intensity, reaction time, the concentration of reactant on the growth of secondary organic aerosol is very important. This paper investigated the effect of environmental factors on SOA formation from biogenic volatile organic compounds (BVOCs), results show that SOA formed from OH-initiated photooxidation of BVOCs is predominantly in the form of fine particles, which have diameters less than 2.5 µm. This paper also highlighted that both the number and mass concentration of SOA particles were increasing with the prolonging of the radiation time, the increasing of light intensity, and the increasing of the reactant concentrations. The results could provide useful information to infer possible emission sources of atmospheric particles in future field measurement.

Abstract: In this study, four nitro-polycyclic aromatic hydrocarbons (Nitro-PAHs), 1-nitropyrene (1-NP)，2-nitrofluorene (2-NF), 9-nitroanthracene(9-NA) and 3-nitrofluoranthene (3-NFl) were quantified in particulate matter collected at six different functional area sites in Dongguan, China, between December 2010 and April 2011. The results showed that concentration levels of nitro-PAHs at the heavy traffic site (DaLing Shan) were higher than those at other sites. Nitro-PAHs were lower in winter than those in spring. Other atmospheric constituents, such as O₃, NOx, NO₂ were also recorded (not at all sampling sites) in order to investigate their correlations with nitro-PAHs concentrations. The results showed that 2-NF and 3-NFl were mostly presented positive correlation with NOx and NO₂, but negative correlation with O₃. There was no significant correlation between 1-NP, 9-NA and the O₃, NOx and NO₂.

Abstract: Palygorskite supported manganese oxide catalysts (MnOx/PG) were prepared for lower temperature selective catalytic reduction (SCR) of NOx by NH₃. Catalyst’s SCR activity was estimated at varied temperatures. Catalyst’s properties were characterized by XRD, NH₃ adsorption and TPD. Results showed that MnOx/PG catalyst was highly active for SCR at low-temperature. It was also found that NH3 was mainly adsorbed on palygorskite in two forms. Weakly adsorbed NH₃, which was seldom inhibited by loading of MnOx, but was more favorable to SCR. Whereas strongly adsorbed NH₃ was more likely to be inhibited by MnOx loading but was inessential for SCR.