[Characteristics of Ozone Pollution Distribution and Source Apportionment in Zhoushan].

The processes affecting photochemical reactions and regional transport of ozone and its precursors in ambient air are very complicated. In this study, statistical analysis of the spatial and temporal distributions of ozone pollution in Zhoushan was carried out based on monitoring data from state monitoring stations in Zhoushan in 2014. Specifically, ozone formation was simulated by CMAQ (the community multiscale air quality) model, and the source contribution rate was calculated using the Integrated Source Apportionment Method (ISAM) source tracking algorithm. The results showed that ozone pollution was more severe in spring and autumn than in summer and winter, and the highest ozone concentrations mostly appeared during 13:00-15:00 in the afternoon. Putuo Station had the highest ozone concentration while Lincheng Station, located in the downtown area of the city, had the lowest ozone concentration. The overall average ozone concentration was not high; however, peak concentrations that exceeded the standards usually occurred, which occurs most often in May. Local ozone formation in Zhoushan City is controlled by the VOC concentration, and source tracking results showed that non-local sources accounted for 69.46% of the total contribution. Among local emission sources, fuel burning boiler sources, industry process sources, on-road mobile sources, and non-road mobile sources made similar contributions to ozone formation. Moreover, they showed significant characteristics of a port city. The contribution rates from shipping sources, petrochemical sources, and storage and transportation sources were 4.45%, 1.01%, and 1.80%, respectively. In conclusion, control of the ozone pollution in Zhoushan City should be based on simultaneous reduction and coordinated prevention involving multiple sources (VOCs as the main one) both locally and in surrounding areas.

Reduction of Fe(II)EDTA-NO by a newly isolated Pseudomonas sp. strain DN-2 in NOx scrubber solution.

Biological reduction of nitric oxide (NO) chelated by ferrous ethylenediaminetetraacetate (Fe(II)EDTA) to N2 is one of the core processes in a chemical absorption-biological reduction integrated technique for nitrogen oxide (NOx) removal from flue gases. A new isolate, identified as Pseudomonas sp. DN-2 by 16S rRNA sequence analysis, was able to reduce Fe(II)EDTA-NO. The specific reduction capacity as measured by NO was up to 4.17 mmol g DCW(-1) h(-1). Strain DN-2 can simultaneously use glucose and Fe(II)EDTA as electron donors for Fe(II)EDTA-NO reduction. Fe(III)EDTA, the oxidation of Fe(II)EDTA by oxygen, can also serve as electron acceptor by strain DN-2. The interdependency between various chemical species, e.g., Fe(II)EDTA-NO, Fe(II)EDTA, or Fe (III)EDTA, was investigated. Though each complex, e.g., Fe(II)EDTA-NO or Fe(III)EDTA, can be reduced by its own dedicated bacterial strain, strain DN-2 capable of reducing Fe(III)EDTA can enhance the regeneration of Fe(II)EDTA, hence can enlarge NO elimination capacity. Additionally, the inhibition of Fe(II)EDTA-NO on the Fe(III)EDTA reduction has been explored previously. Strain DN-2 is probably one of the major contributors for the continual removal of NOx due to the high Fe(II)EDTA-NO reduction rate and the ability of Fe(III)EDTA reduction.

Evaluation of microbial reduction of Fe(III)EDTA in a chemical absorption-biological reduction integrated NOx removal system.

A chemical absorption-biological reduction integrated process can be used to remove nitrogen oxides (NOx) from flue gas. In such a process, nitric oxide (NO) can be effectively absorbed by the ferrous chelate of ethylenediaminetetraacetate (Fe(II)EDTA) to form Fe(II)EDTA-NO, which can be biologically regenerated by denitrifying bacteria. However, in the course of these processes, part of the Fe(II)EDTA is also oxidized to Fe(III)EDTA. The reduction of Fe(III)EDTA to Fe(II)EDTA depends on the activity of iron-reducing bacteria in the system. Therefore, the effectiveness of the system relies on how to effectively bioreduce Fe(III)EDTA and Fe(II)EDTA-NO in the system. In this paper, a strain identified as Escherichia coli FR-2 (iron-reducing bacterium) was used to investigate the reduction rate of Fe(III)EDTA. The experimental results indicate that Fe(III)EDTA-NO and Fe(II)EDTA in the system can inhibit both the FR-2 cell growth and thus affect the Fe(III)EDTA reduction. The FR-2 cell growth rate and Fe(III)EDTA reduction rate decreased with increasing Fe(II)EDTA-NO and Fe(II)EDTA concentration in the solution. When the concentration of Fe(II)EDTA-NO reached 3.7 mM, the FR-2 cell growth almost stopped. A mathematical model was developed to explain the cell growth and inhibition kinetics. The predicted results are close to the experimental data and provide a preliminary evaluation of the kinetics of the biologically mediated reactions necessary to regenerate the spent scrubber solution.

Study on NO(2) absorption by ascorbic acid and various chemicals.

Study on NO(2) absorption aimed at seeking a better NO(2) absorption chemical at pH 4.5 approximately 7.0 for application to existing wet flue gas desulfurization (FGD). The results from the double-stirred reactor indicated that ascorbic acid has very high absorption rate at this pH range. The rate constant of ascorbic acid reaction with NO(2) (0 approximately 1,000 x 10(-6) mol/mol) is about 3.54 x 10(6) mol/(Ls) at pH 5.4 approximately 6.5 at 55 degrees C.

Experimental study on the inhibition of biological reduction of Fe(III)EDTA in NO(x) absorption solution.

Scrubbing of NO(x) from the gas phase with Fe(II)EDTA has been shown to be highly effective. A new biological method can be used to convert NO to N(2) and regenerate the chelating agent Fe(II)EDTA for continuous NO absorption. The core of this biological regeneration is how to effectively simultaneous reduce Fe(III)EDTA and Fe(II)EDTA-NO, two mainly products in the ferrous chelate absorption solution. The biological reduction rate of Fe(III)EDTA plays a main role for the NO(x) removal efficiency. In this paper, a bacterial strain identified as Klebsiella Trevisan sp. was used to demonstrate an inhibition of Fe(III)EDTA reduction in the presence of Fe(II)EDTA-NO. The competitive inhibition experiments indicted that Fe(II)EDTA-NO inhibited not only the growth rate of the iron-reduction bacterial strain but also the Fe(III)EDTA reduction rate. Cell growth rate and Fe(III)EDTA reduction rate decreased with increasing Fe(II)EDTA-NO concentration in the solution.