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Based on data from the air quality monitoring stations in the Pearl River Delta during the 2015 Spring Festival, the regional air quality was investigated and the impact of burning fireworks on urban air quality was assessed. The results showed that: Zhaoqing was the worst polluted city in PM₁₀, PM₂.₅, SO₂ and CO in terms of concentrations in the region during the period, Huizhou was the worst polluted city in O₃ and Guangzhou was the most polluted city in NO₂ at the same time. Compared to the data of last year, the SO₂, NO₂, CO, PM₁₀ and PM₂.₅ concentrations had decreased significantly, but the O₃ concentration had increased during the Spring Festival. Burning fireworks during the Spring Festival were mainly concentrated in the suburbs. The concentrated discharge of fireworks made the SO₂, PM₁₀ and PM₂.₅ concentrations increased significantly in the New Year's Eve night, even multiplied, but had no significant effect on CO, O₃ and NO₂. The rapid decline in PM₂.₅/PM₁₀ proportion was caused by the discharge of fireworks, and the ratio of PM₂.₅/PM₁₀ reached the minimum when concentration of particles reached the peak. By assessing, the maximum contribution of hourly concentration from burning fireworks in each city was between 16 µg · m⁻³ and 65 µg · m⁻³ for PM₂.₅, between 28 µg · m⁻³ and 138 µg · m⁻³ for PM₁₀ and between 9 µg · m⁻³ and 43 µg · m⁻³ for SO₂.

Daily (24-h average) PM2.5 samples were collected simultaneously at urban and suburban sites of nine cities (Nanning, Qinzhou, Fangchenggang, Beihai, Zhanjiang, Maoming, Haikou, Yangpu and Dongfang) in Beibu Gulf Zone during August 2009. All samples were analyzed for organic and elemental carbon (OC and EC) analyses by the thermal/optical reflectance following IMPROVE protocol. Characteristics of OC and EC concentration levels, spatial distribution, and the possible sources were discussed. The average concentrations of PM2.5, OC and EC in Beibu Gulf zone were (38.4 +/- 17.7), (9.2 +/- 2.6) and (1.9 +/- 1.1) microg x m(-3), respectively. The total carbonaceous aerosol (TCA) accounted for over 56.8% of PM2.5. OC mainly came from biomass burning and secondary organic carbon (SOC), while motor exhaust and industrial emissions were the primary source of EC during summer in Beibu Gulf Zone.

The kinetics method of the substrate reaction during modification of enzyme activity previously described by Tsou (Adv. Enzymol. Related. Areas Mol. Biol., 1988, 61, 381-436) has been applied to study the kinetics of the course of inactivation of green crab alkaline phosphatase by phenylglyoxal. The obtained results shows that the inactivation of the enzyme by phenylglyoxal is a slow reversible reaction. The microscopic rate constants for the reaction of the inhibitor with the enzyme were determined. The presence of substrate offers marked protection of this enzyme against inactivation by phenylglyoxal. The above results suggest that the arginine residue is essential for activity and is situated at the active site of the enzyme.

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme, which catalyzes the nonspecific hydrolysis of phosphate monoesters. The present paper deals with the study of the effect of some kinds of metal ions on the enzyme. The positive monovalent alkali metal ions (Li(+), Na(+) and K(+)) have no effect on the enzyme; positive bivalent alkaline-earth metal ions (Mg(2+), Ca(2+) and Ba(2+)) and transition metal ions (Mn(2+), Co(2+), Ni(2+) and Cd(2+)) activate the enzyme; heavy metal ions (Hg(2+), Ag(+), Bi(2+), Cu(2+) and Zn(2+)) inhibit the enzyme. The activation of magnesium ion on the enzyme appears to be a partial noncompetitive type. The kinetic model has been set up and a new plot to determine the activation constant of Mg(2+) was put forward. From the plot, we can easily determine the activation constant (K(a)) value and the activation ratio of Mg(2+) on the enzyme. The inhibition effects of Cu(2+) and Hg(2+) on the enzyme are of noncompetitive type. The inhibition constants have been determined. The inhibition effect of Hg(2+) is stronger than that of Cu(2+).

The toxicity of NO3- and NO2- to mammals has been widely publicized. However, the kinetic mechanism of inhibition of human muscle creatine kinase by NO3- and NO2- has not been explored. The kinetic theory of the substrate reaction during the modification of enzyme activity previously described by Tsou (Adv. Enzymol. Related Areas Mol. Biol. 1988, 61, 381-436) has been applied to a study of the kinetics of slow reversible inhibition of human muscle creatine kinase by planar anions (NO3- and NO2-). The kinetic equation of the substrate reaction was derived from theoretical analysis and experimental data, then simplified. The microscopic rate constants for the reaction of the inhibitors with the enzyme were obtained from the simplified equation for the substrate reaction in the presence of the inhibitors. The results show that the apparent forward rate constant A is dependent on ATP concentration, indicating competition between the inhibitor (NO3- or NO2-) and ATP. The results also suggest that binding of creatine-MgADP and the anion with the enzyme is very tight, since their binding constants are much higher than those for normal substrates.