Visibility sulfur dioxide effect

From the commencement of the fog and low visibility, many people experienced difficulty breathing, the effects occurring more or less simultaneously over a large area of hundreds of square kilometers. The rise in the number of deaths (Fig. 18-4) paralleled the mean daily smoke and sulfur dioxide concentrations daily deaths reached a peak on December 8 and 9, with many of them related to respiratory troubles. Although the deaths decreased when the concentrations decreased, the deaths per day remained considerably above the pre-episode level for some days. Would most of the persons who died have died soon afterward anyway If this were the case, a below-normal death rate would h ve occurred following the episode. This situation did not seem to exist, but detailed analysis was complicated by increased deaths in January and February 1953 which were attributed primarily to an influenza outbreak. 

Early work with sulfur dioxide showed a linear relationship between visible injury and reduction in yield for many crop species. The assessment was made that no reduction in yield would be found unless visible injury were noted. Definitive research with ozone, other oxidants, or mixtures of these pollutants with other gases has not been done. Thus, we do not know whether such relationships between visible injury and yield hold for the oxidants, but data in Table 11-3 suggest that for acute exposures there may be good correlations between injury and yield reductions. Many researchers have hypothesized that the oxidants may have an effect on plants that will produce a yield reduction with little or no visible injury. Such studies need to be designed in a more defmitive manner before it is concluded that yield reductions without visible symptoms are clearly acceptable. Projections of yield losses have made use of some of the data reported earlier. ... 

Table II includes supporting data for greater-than-additive inhibition of alfalfa apparent photosynthetic rates induced by SO2+NO2 mixtures. The enhanced effects were most marked at the lower concentrations applied, becoming less pronounced as pollutant levels were raised. At 50 pphm of each gas no synergism was evident. At this SO2 exposure concentration, sulfur dioxide appeared to regulate the observed plant responses. Significant amounts of inhibition resulted from the lowest bipollutant concentrations used (15 pphm of each gas) these concentrations were well below those required for the individual pollutants to measurably suppress apparent photosynthesis rates. At these exposure levels where no tissue necrosis occurred, the plants recovered completely within 2 hr after fumigation. The manner by which this inhibiting interaction occurred is not well understood. This pollutant combination is also known to act in a synergistic fashion to cause visible injury to plants, and further study of this mixture may be warranted.

Sulfur dioxide. The sources are burning coal and oil, especially high sulfur coal from Eastern US, and industrial processes (paper and metal industry). Health effects include breathing problems, which may cause permanent damage to lungs. Environmental effects are as follows S02 is an ingredient of acid rain (acid aerosols), which can damage trees and life in lakes. Acid aerosols can also reduce visibility. 

Acute symptoms of injury from various pollutants in different horticultural and agronomic groups are visible on the affected plant. Symptom expressions produced include chlorosis, necrosis, abscission of plant parts, and effects on pigment systems. Major pollutants which produce these injuries include sulfur dioxide, peroxyacetyl nitrate (PAN), fluorides, chlorides, nitrogen dioxide, ozone, and particulate matter minor pollutants are ethylene, chlorine, ammonia, and hydrogen chloride. Symptoms of acute injury are often used to identify pollutant source and to estimate agricultural damage. 

These data and those of others (1, 5, 6, 26, 27) indicate a change in growth rate and/or a reduction in leaf area after prolonged exposure to sulfur dioxide. These effects indicate possible alterations in the normal physiological functioning of the plant, and therefore probably have both a visible (ultrastructure) and biochemical basis. 

However, this does not preclude following the effects on plant growth of chronic exposure to low levels of sulfur dioxide. Injury is manifested in altered growth rates, reduction in plant size, and alteration in reproductive capacity, all of which are visible only if the plants can be compared with others of the same variety growing under nonpolluted condi-... 

Mechanical Passivity.—In certain instances the dissolution of an anode is prevented by a visible film, e.g., lead dioxide on a lead anode in dilute sulfuric acid this phenomenon has been called mechanical passivity, but it is probably not fundamentally different from the forms of passivity already discussed. The film is usually not completely impervious, but merely has the effect of decreasing the exposed surface of the electrode to a considerable extent the effective c.d. is thus increased until another process in which the metal is involved can occur. At a lead anode in sulfuric acid, for example, the lead first dissolves to form plumbous ions which unite with the sulfate ions in the solution to form a porous layer of insoluble lead sulfate. The effective c.d. is increased so much that the potential rises until another process, viz., the formation of plumbic ions, occurs. If the acid is sufficiently concentrated these ions pass into solution, but in more dilute acid media lead dioxide is precipitated and tends partially to close up the pores the layer of dioxide is somewhat porous and so it increases in thickness until it becomes visible. Such an oxide is not completely protective and attack of the anode continues to some extent it is, however, a good conductor and so hydroxyl ions are discharged at its outer surface, and oxygen is evolved, in spite of its thickness. 

Venus -- has a slow rotation when compared to Earth. Venus and Uranus rotate in opposite directions from the other planets. This opposite rotation is called retrograde rotation. The surface of Venus is not visible due to the extensive cloud cover. The atmosphere is composed mostly of carbon dioxide. Sulfuric acid droplet in the dense cloud cover gives Venus a yellow appearance. Venus has a greater greenhouse effect than observed on Earth. The dense clouds Combined with carbon dioxide traps heat. Venus was named after the Roman goddess of love. 

Ti02 nanoparhcles, as-doped, could also be used for the disinfection of waste-water. For example, Yu et al. reported that sulfur-doped titanium dioxide exhibited a strong visible-light-induced anhbacterial effect [29], while Egerton et al. found that the photoelectrocatalytic disinfechon of E. coli by an iron-doped Ti02 sol-gel electrode was more efficient than disinfection by the corresponding electrode when undoped [30]. 

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