Advanced Materials Research Vols. 726-731

Abstract: A modified denitrifier method on Tracegas-isotope ratio mass spectrometry (IRMS) was developed to determine the nitrogen and oxygen isotopic compositions of nitrate (NO₃^-) in water samples. The protocol presented in our previous publication was modified in several aspects. Then, the incubation time, amount of NO₃^- sample, and effect of trapping time in the Tracegas system were analyzed using the standard reference USGS34. Both δ¹⁵N and δ¹⁸O values demonstrated accurate and reproducible at incubation times exceeding 12 h or overnight as well as added 0.2 μg to 0.4 μg NO₃^--N samples. Our data also showed that 100 s for trapping time in Tracegas system was adequate to achieve accurate and reproducible results. Finally, the δ¹⁵N and δ¹⁸O values of nitrate in animal wastewater were measured using this method. The results indicate that the denitrifier method can be used widely for tracing nitrate sources and controlling nitrate contamination in China.

Abstract: To detect the sanitary status of pure water at different times in the campus, including to detect the total bacterial count, the coliforms, mould and yeast, this document explained and demonstrated the sanitary status of the barreled pure water through water dispensers. By the experiment, the results showed that the drinking fountain caused the pure water pollution, so the unheated pure water flowing though the drinking fountain were not qualified. And the longer the pure water samples were cultured, the more the aerobic bacterial count of water samples significantly exceeded the standard. After these samples were cultured for five days, all samples had be uncountale.

Abstract: Using Fluent to simulate dangerous heavy gas leakage and diffusion of oil tank farm under different conditions. The analysis results show that the diffusion processes of heavy gas can be divided into four stages like gravity settling stage, air entrainment stage, cloud heating stage and the stage of transformation to the non-heavy gas diffusion. While the gas leakage occurs in the middle position of the tank farm, the gas diffusion speed is slow and the gas concentration is easy to achieve the explosive limit. When the wind velocity is 0.95 m/s, the diffusion velocity of heavy gas increases with the wind velocity, gas concentrations rises obviously. When the wind velocity reaches to 1.7 m/s, the gas concentration will reach the peak, as the wind velocity increases, the gas concentration reduces slowly.

Abstract: In this paper, we study the optimal harvesting strategy of inshore-offshore species. Firstly, to keep sustainable harvest of inshore-offshore species resources, the stability of the system is discussed by Lyapunov method. Then, the optimal harvesting strategy is obtained by simple mathematical analysis.

Abstract: Nessler's reagent spectrophotometry method is used for determination of water quality ammonia nitrogen. The method is affected by many factors, of which Nessler's reagent is the most critical factor. Preparation and adding methods of Nessler's reagent influence the results of determination , which is based on the determination of absorbance and recovery test. Experimental results show that in the strict control of the speed and the amount of HgCl₂ accession, we can get the best effect in the course of preparation of Nessler's reagent. Put a volume of standard solution into a 50mL colorimetric tube, add into Nessler's reagent when diluted with water to about 40mL and then add into water to the reticle (constant volume to 50mL). Determine the absorbance when colors are shown. Draw calibration curve with absorbance as ordinate and mass concentration of ammonia nitrogen as abscissa. The quality control effect of the determination of ammonia nitrogen can be improved by reducing uncertainties.

Abstract: Based on previous studies, 130 shallow groundwater samples are collected from Huainan city according to some rules, and 21 indexes of the groundwater samples are tested by different instruments. Moreover, the important works have been done, including statistical characteristics of groundwater components, and divided different types of hydrochemistry, analyses of the relationships between the hardness and Ca2+/Na+, Mg2+/Na+, TDS and the ES. The correlation between heavy metals and conventional components has been discussed. Finally, main components have influence on the quality of shallow groundwater by the method of principal component analysis.

Abstract: The campus indoor environment is an important learning and living environment for college students, and it is closely related to the health of college students. Using natural sedimentation to monitor and evaluate the indoor air microorganisms of four classrooms (0407, 0408, 0409 and 0410) which are in the Inner Mongolia University campus comprehensive building of fourth floor. The results show that the concentration variation of indoor air microorganisms is different in one day, in the 5 periods of time from morning to night, the maximum is 2.0×10³ cfu·m^-3 in the morning, which is 12 times to the minimum. Air microbial content of the sunny classrooms (0407 and 0409) is obviously higher than night side classrooms (0408 and 0410), the total bacteria concentration of classroom 0407 is 2.1 times to classroom 0408, and the concentration of classroom 0409 is 1.5 times to classroom 0410. Among the 4 sampling points, the highest total concentration of air microorganisms is 8.0×10² cfu·m^-3, the lowest value is 3.0×10² cfu·m^-3, and the average value is 6.0×10² cfu·m^-3. Bacteria as the main air microorganism in summer campus classroom, accounted 77.4%, mold accounted18.9%, actinomycetes accounted 3.7%. According to the air microorganism standards, it evaluates that each time of indoor air is clean.

Abstract: The Typhoon Morakot raged through Taiwan bringing torrential rain for two days, which led to debris-flow in mountains and severe flooding in the coastal areas of southern Taiwan. In order to realize the impact of the Typhoon Morakot on heavy metals in the sediments this research discriminate the pollution brought from three neighboring rivers to the Dapeng Bay lagoon by using the R. A. Fisher Method. The results generally indicate that the samples from Dapeng Bay and the three neighboring rivers are displaying individual crowd-distribution phenomena, which means that the heavy metal content in the sediments of Dapeng Bay and the three neighboring rivers are not totally similar. Today, due to a massive variation in eco-habitat and a more frequently changing climate, the understanding of spatial-temporal variation of heavy metal pollution of sediments in Dapeng Bay and pollution sources from three neighboring rivers will provide useful information regarding disaster management, habitat recovery, operative management, as well as ecotourism specification.

Abstract: Spatial distribution characteristics of available phosphorus (AP) and total phosphorus (TP) in wetland soils with Phragmites australis, Suaeda salsa and Tamarix chinnensis were investigated and their influencing factors was also indentified using principal correspondence analysis for ordination in the Yellow River Delta of China. Our results showed that TP and AP contents in both sites with Phragmites australis and Suaeda salsa, and the horizontal distributions of AP content in three sites exhibited similar distribution characteristics to that of AP:TP ratios. Additionally, soil properties such as soil moisture, salinity, total nitrogen, total carbon and pH values were the important influencing factors of higher spatial variability of AP and TP.

Abstract: A simple and sensitive electrochemical method for the nonenzymatic detection of hydrogen peroxide (H₂O₂) has been proposed. Highly dispersed Ag nanoparticles (NPs) were synthesized under microwave irradiation with PAMAM dendrimer as reductant and stabilizer. The formation of Ag NPs decorated with PAMAM dendrimer (Ag-G3.5-PAMAM) was confirmed by ultraviolet visible spectrophotometer (UV-vis). The as-prepared Ag-G3.5-PAMAM was used to modify the glassy carbon electrode (GCE) for nonenzymatic detection of hydrogen peroxide. It is showed that the fabricated electrochemical sensor based on Ag-G3.5-PAMAM exhibits fast response to hydrogen peroxide.The result indicates that Ag-G3.5-PAMAM may have promising applications in the development of nonenzymatic sensor for hydrogen peroxide in the future.