Efficiency of triggered barriers in dust explosion suppression in galleries

The paper describes large-scale tests of triggered barriers of different design. Main stress was put on examining suitability of the flame detector developed in US Bureau of Mines to work as a trigger for the barriers. It was found that the detector works satisfactorily with the barriers of different design providing a suitable mean to suppress explosions in galleries, either in mines or in other industries.     

The effect of chlorine position of chlorinated phenols on their dechlorination kinetics by Fenton's reagent

Chlorine position of chlorophenol isomers has a significant effect on the dechlorination kinetics of monochlorophenols, dichlorophenols, and trichlorophenols during Fenton oxidation. The effects have been evaluated by the rate constants of the dechlorination kinetic model developed in this study. It is found that the dechlorination rate of 3-CP is faster than that of 4-CP, which is faster than that of 2-CP. Since OH and Cl groups on the aromatic ring are ortho and para directors, the directory effect of OH and Cl groups enhances the dechlorination kinetics of 2-CP due to acceleration of the hydroxylation of 2-CP. Therefore, the dechlorination kinetics increases accordingly. For trichlorophenols (TCP), steric hindrance plays an important role during their dechlorination process. Specifically, the closer the chlorine atoms locate with each other on the aromatic ring, the more difficult the dechlorination processes will be. The dechlorination kinetics of dichlorophenols seems to be affected by both directory effect of OH and Cl groups and the effect of steric hindrance of chlorine atoms. The directory effect of OH and Cl groups on trichlorophenols decreases since the chlorine atom occupied the positions which are the most favorable for hydroxyl radical attack.     

Effect of phosphate fertilizer application on phosphorus (P) losses from paddy soils in Taihu Lake Region. I. Effect of phosphate fertilizer rate on P losses from paddy soil

A field plot study was conducted on two types of paddy soils in the Taihu Lake Region, during the rice season of year 2000 in order to assess phosphorus (P) losses by runoff and vertical leaching, which are considered the two main pathways of P movement from paddy soil into its surrounding water course. Commercial NPK compound fertilizer and single superphosphate fertilizer were applied to furnish 0, 30, 150, and 300 kg applied P ha m(-2). The experiments consisted of three replicates of each treatment in Changshu site and four replicates in Anzhen site, with a plot size of 5 x 6 m2 in a randomized block. Results revealed that the average concentration range for total P (TP) in runoff was 1.857-7.883, 1.038-5.209, 0.783-1.255 and 0.572-0.691 mg P l(-1) respectively for P300, P150, P30 and P0 in Anzhen, while it was 2.431-2.449, 1.578-1.890, 1.050-1.315 and 0.749-0.941 mg P l(-1) respectively in Changshu. In all treatments, particulate P (PP) represented a major portion of the TP lost in runoff, it was 80% in Anzhen, and it was even more (>90%) in Changshu. Phosphate fertilizer treatments significantly affected P concentrations and P loads in the runoff. The mean concentration and average seasonal TP load from the P150 plots were 1.809 mg P l(-1) and 395 g P ha m(-2) season(-1) respectively, and lower than that from the P300 plots (2.957 mg P l(-1) and 652 g P ha m(-2) season(-1)). These were obviously higher than from the P30 (0.761 mg P l(-1) and 221 g P ha m(-2) season(-1)) and P0 (0.484 mg P l(-1) and 146 g P ha m(-2) season(-1)) respectively. There was no significant difference found between the P30 and the P0 in both sites. Under usual P application rate, there were total 31.7 and 20.6 tones P removed by runoff from permeable (Anzhen site) and waterlogged (Changshu site) paddy soils in the southern Jiangsu region (major part of the TLR) in the rice season of the year 2000. But if the P application rate is unusual high, or the Olsen P in soil accumulates to above a certain level, then this could sharply increase in the future. The average concentration of molybdate reactive phosphorus (MRP) in the vertical leachate from the four different P treatments ranged from 0.058 to 0.304 mg P l(-1) in Anzhen and from 0.048 to 0.394 mg P l(-1) in Changshu. P application rate significantly affected the MRP concentration at each depth in both sites, except for the 90 cm in Anzhen. The average MRP loads during the rice season moved by vertical leaching from the four treatments ranged from 163 to 855 g P ha m(-2) season(-1) in Anzhen and 208-1,825 g P ha m(-2) season(-1) in Changshu. Vertical leachate movement does not necessarily mean that it moves towards surface water and contaminate the watercourses in this flat plain paddy soil region, it does, however, imply that P can move down from surface layers of soil to deeper levels.     

Interactions between arbuscular mycorrhizae and heavy metals under sand culture experiment

A sand culture experiment was established to determine interactions between arbuscular mycorrhizae and heavy metals. Mycorrhizal infection rates, spore densities, maize root and shoot weights, and heavy metal contents in maize were as indexes of responses of arbuscular mycorrhizal fungi (Acaulospora laevis, Glomus caledonium and Glomus manihotis) to heavy metals (Cu and Cd). The mycorrhizal infection rates of G. caledonium were the highest among these three mycorrhizal fungi, but the sporulating ability of G. caledonium was the poorest in the heavy metal treatments. The shoot and root weights of non-mycorrhizal plants were usually greater than those of mycorrhizal plants when the Cu concentrations in solutions are less than 3 mg l(-1) or Cd concentrations less than 1 mg l(-1). When Cd concentrations were 0.5 and 1 mg(-1), the root and shoot weights of plants inoculated with A. laevis were significantly (p < 0.05) lower than those of other treatments. Copper concentrations in shoots of mycorrhizal plants were higher than those of non-mycorrhizal ones at all Cu concentrations in solution, especially at low Cu concentrations. As to A. laevis, Cu concentrations in roots and shoots of the host were higher than those of non-mycorrhizal plants in these treatments. Thus A. laevis was sensitive to Cu and Cd, especially Cd, and G. caledonium was more tolerant to these two heavy metals. It is suggested that G. caledonium might be a promising mycorrhizal fungus for bioremediation of heavy metal contaminated soil.     

Seeking for Your Own Sake: Chinese Citizens’ Motivations for Information Seeking About Air Pollution

Based on data from a Qualtrics panel, this study examines Chinese citizens’ motivations for information seeking about air pollution. Results from structural equation modelling indicate that information insufficiency, negative affect, attitudes toward seeking, and perceived information gathering capacity are positively related to information seeking. Informational subjective norms, however, were not significantly related to information seeking. Further, participants with more knowledge and higher risk perception were more likely to desire more information about air pollution. These results suggest that communication campaigns should highlight individuals’ personal risks and self-efficacy to encourage greater information seeking about air pollution among Chinese citizens. Emotional appeal may serve as an effective strategy as well.     

Significant radioactive contamination of soil around a coal-fired thermal power plant

Soil samples were collected around a coal-fired power plant from 81 different locations. Brown coal, unusually rich in uranium, is burnt in this plant that lies inside the confines of a small industrial town and has been operational since 1943. Activity concentrations of the radionuclides 238U, 226Ra, 232Th, 137Cs and 40K were determined in the samples. Considerably elevated concentrations of 238U and 226Ra have been found in most samples collected within the inhabited area. Concentrations of 235U and 226Ra in soil decreased regularly with increasing depth at many locations, which can be explained by fly-ash fallout. Concentrations of 235U and 226Ra in the top (0-5 cm depth) layer of soil in public areas inside the town are 4.7 times higher, on average, than those in the uncontaminated deeper layers, which means there is about 108 Bq kg(-1) surplus activity concentration above the geological background. A high emanation rate of 222Rn from the contaminated soil layers and significant disequilibrium between 238U and 226Ra activities in some kinds of samples have been found.     

Ecological Consequences of Atmospheric Ozone Depletion in Northern Regions (Arkhangelsk Oblast)

Data on skin cancer morbidity and the total ozone concentration in the atmosphere over Arkhangelsk were processed using a standard method. The results showed that ozone depletion contributes to the increase of morbidity accounted for by this nosological form.