The third-order rate constants for the pure water and acid precipitation systems were measured to be (7.1 ±1.5) × 107L2/mol2·s and (5.3±2.6) ×107L2/mol2·S, respectively.
The high ratio of(ρ(NH_4~+)+ρ(Ca~(2+)))/(ρ(SO_4~(2-))+ρ(NO_3~-))with the value 1.93 is thought to be the main reason for the restraining of acid precipitation forming revealing strong antacid ability of the atmospheric environment.
Based on the analyses of data of precipitation, air pollution index and meteorology in Nantong area from 1991 to 1997, the paper indicates the difference of precipitation in space and time, high frequency of acidic precipitation in urban area and the difference related to pollutants such as SO 2、NO x and weather.
and even it can promote the formation of acidic precipitation Such kind of pollution characteristic is also one of important causes accounting for the occurrence of acidic precipitation at the above sites
In order to understand relations between atmospheric aerosols and acidic precipitation ,acidity of inhalable particulates (PM 10 ) at different sites in northern and southern China is analyzed Micro titration is adopted to determine their acidifying buffer capacity Results shows that aerosols have certain acidity and their acidifying buffer capacity for acidification is rather low;
The pH values show a remarkable seasonal variation, with more acid rain fall in winter than that in spring, autumn and summer. The SO42-+NO3-/NH4++Ca2+ ratio ranged from 0.9 to 1.3 was higher than that in northern China and southwest China (with the ranged from 0.4 to 0.7 and 1), this implied that the acid deposition was severe in Simian Mountain.
In Guangzhou area, formation of acid rain was due to the presence of SO_4~(2-) and NO_3~- covering more than 70% of total anions with SO_4~(2-) as main anion.
A lectin present in seeds of Trigonella foenumgraecum was isolated and purified by acid precipitation, salt fractionation, and affinity chromatography on mannan cross-linked agarose.
The purification procedure included four steps: ammonium sulfate precipitation, acid precipitation, hydrophobic chromatography, and gel-filtration chromatography.
The influence of the salt composition of casein-water-Cd(NO3)2 and defatted milk-Cd(NO3)2 systems on the partitioning of Cd2+ during acidic precipitation of casein was studied.
Acidic precipitation as a stress factor of the host plant apparently changes population dynamics of pine sawflies and may be an important factor in triggering outbreaks.
Mineral components in some fine sand and clay samples were compared, and their weathering potentiality and buffering capacity against acidic precipitation were discussed.
In-lake alkalinity generation resulting from sulfate reduction has been sufficient to neutralize all of the acid falling directly onto the lake surfaces, as well as between 9% and 25% of the acid deposited onto the surrounding watersheds.
The acidity of precipitation in equilibrium with atmospheric CO2 and SO2 has been calculated for both clean and polluted areas. It shows that in temperate latitudes the pH value of precipitation in clean areas is below 5 due to the existence of SO2 and CO2. In Beijing, where the aerosol concentration is high, the pH value of precipitation is increased by the reactivity of chloride and CaO with acidic substances. The pH value of precipitation in Beijing is closely related to the liquid water content in cloud...
The distribution of available aluminium in soils in northern Guizhou area was investigated. The results show that the mean level of active aluminium in the soils is rather low at present time, indicating no significant effect on agricultural and forest ecosystems. However, the acid precipitation which leachs the aluminium out from the soils may be a potential danger.
The acidity of precipitation in Guangzhou is studied.It points out that Guangzhou is acid- sensitive and the frequency for acid rain to take place is about 60 per cent in the urban area. Acidity of rain is strong in spring and weak in summer. Under stable weather conditions, such as inversion or breeze, acid rain is produced easily. Results of chemical analysis of rain sample show that effect of local pollution source is obvious on acid rain in the city.
酸性降水
acid precipitation
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