During a period from February let to November 30th in 1983, measurements were made twice a month on dustfalls and concentrations of various cations and anions in their filtrates in an urban (Heuksuk-dong, Seoul) and in a rural (Ansung) districts.
Standard British Deposit Gauge method was applied for collection of dustfalls and ion chromatographic method using Ion Chromatograph 10 (Dionex, U.S.A.) for determination of cation and anion concentrations.
The results obtained were as follows:
1. Annual mean values of dustfalls were 8.30±5.09 tons/km2/month in an urban and 6.20±0.82 tons/km2/month in a rural districts. And annual mean values of pH of filtrates of the collected samples were 5.3±0.76 in an urban and 6.0±0.82 in a rural districts.
2. Annual mean concentrations of common cations and anions in their filtrates were as follows:
urban rural (unit: ppm)
Na+ 1.7±1.30 1.9±1.86
NH4+ 2.4±1.60 1.3±1.59
K+ 0.7±0.47 1.5±3.79
Ca++ 5.3±0.95 3.4±2.58
M9++ 0.7=0.89 .0.5±0.83
Cl- 2.0±1.31 4.0±2.35
N03 4.0±2.35 2.7±1.31
So4 16.9±17.40 6.8±8.00
Some of anions such, as Br-, P04-3 and,-NOZ were scarecely detected and F- was measu red at very low concentrations ranging from 0.1 to 0.5 ppm in Feb., Oct. and Nov. in an urban and in Feb. in a rural districts.
3. By two-way analysis of variance with 4 replications for dustfalls, pH and concentrations of various ion by district and month of a year, statistically significant differences were noted in dustfalls (p<0.01), pH (p<.01) and concentrations of various ion (p<0.01) by month of a year, and in dustfalls (p<0.05) and concentrations of various ion such as NH4+, Ca++, N03 and S04__ (p<0.01) by district.
4. There were statistically significant differences pH in Spring (Feb., Mar. and Apr.) (p<0.01) and in 5047- in Autumn (Aug., Sept., Oct. and Nov.) (p<0.05) between the two districts.
|