| Abstract | Four sites for atmospheric deposition measurement were set up at Viettri, an industrial site;
Lang, a commercial and trade center; Phulien, a site representative of a coastal environment
and Cucphuong, a rural site. The data set comprises 66 rain event samples, 16 monthly rain
samples and 16 monthly dry deposition samples collected over a four month period from
January to April 1997. The analyses were done for So/·, N03-, er, F", No2·, HPo/·, Na+,
Mg2
+, K+, Ca2
+, Ba2
+, Ir using an Ion Chromatograph. The equipment had proved to be a
sensitive method in identifying ions of atmospheric deposition.
Data on pH of rain water from 1991 to 1996 were also collected at ten sites in the North of
Vietnam. In general, the rain water pH was in the range of 5.0 to 7.0. However, during the
winter and the beginning of autumn, when the rainfall was low, NE and E wind directions were
dominant, the pH values were found to be lower as compared to other times of a year. In
general, pH in Viettri was observed to be the lowest of all monitored sites. The average pH of
event rain samples in Viettri during this period of study was 5. 5. The correlations between ion
H+ and anions So/·, N03-, er of samples in Viettri were found to be higher than other sites,
i.e., 0.28, 0.38, 0.51, respectively.
In general, Ca2
+ and SO/ are predominant species in both wet and dry atmospheric deposition
samples. However, the concentrations of chemical species found in monthly dry deposition
samples were lower than those of monthly wet deposition samples at all sites.
It was observed that the atmospheric concentrations of S02 and NOx were observed to be
higher in Lang, corresponding with higher concentrations of So/· and N03- of both wet and
dry deposition.
Based on the increased energy consumption in Vietnam, the gross total gaseous emission of
NOx and S02 was estimated to be increased about 2 times in the period from 1985 to 1995. |