The main objective of this project is to monitor the water quality of seven cities and counties in the southern part of Taiwan in order to track the seasonal variability in water quality and to analyze and assess the degree of pollution of various bodies of water. The results of this investigation can provide grounds for policy making to environmental protection authorities.
One hundred and nine sampling sites covering 32 rivers, including main streams and tributaries, were monitored monthly for river water quality. The results indicated that the water quality of Zeng-Wen River basin and rivers within Pingdong county were the best, while Jiang-Jun River, Er-Ren River and A-Gong-Dian River basins were found to have relatively high levels of pollution. There was a major drought this year; in particular, the lack of rainfall from January to June made parts of some rivers nearly run dry, so test results for most pollutants were high; thus, the percentage of serious pollution looked high. Due to plenty of rainfall from July through October, the suspended solids in the rivers tended to be high; thus the percentage of unpolluted rivers was low and over 50% of the results indicated that rivers were intermediately polluted. As a whole, the water quality of the intermediately polluted rivers accounted for 41.0%, which constituted the highest proportion of the rivers investigated, and non- or slightly polluted rivers accounted for 31.1%. Overall, no major difference in water quality was observed when compared to the historical data.
Forty-two sampling sites covering eight coastal areas were monitored quarterly for ocean water quality. Since the river affected the estuary areas during high tide, the concentrations of phosphate, nitrate and silicate were high. The results indicated that most analytes met the quality criteria for each individually specified ocean water category except the results of dissolved oxygen and ammonia nitrogen at estuary areas of Er-Ren River and Dong-Gang River. Because of rainfall which came just before the sampling period in the 3rd and 4th quarters, some indexes, including salinity, phosphate, nitrate and silicate, were different from past results.
Thirty sampling sites covering ten beaches were monitored weekly from the end of June through August. The results indicated that the water qualities were all excellent. Due to much rainfall on July 17 and 31, the results of these two weeks were fair.
Forty-five sampling sites covering 17 water reservoirs were monitored quarterly. All reservoirs were found to contain certain sampling sites that did not meet the Class A surface water quality criteria. The results indicated that Lan-Tan Reservoir had the best water quality, which was oligotrophic for three of the four quarters. Ren-Yi-Tan Reservoir, Wu-Shan-Tou Reservoir and Mu-Dan Reservoir were found to be oligotrophic in one quarter and mesotrophic in the other three quarters. Feng-Shan Reservoir was found to have the worst water quality which was eutrophic in all four quarters.
Ammonia nitrogen, iron, and manganese were the major analytes with results that reached the regulatory monitoring criteria in 202 groundwater monitoring wells for the seven cities and counties being monitored quarterly. The failing rates were between 0% to 89.5% for different cities and counties. No significant difference was found when compared to the historical data. The graphical analysis of the monitored locations by Stiff-plotting and Piper-plotting showed that about 60% of the wells are HCO3－+CO32－- Ca2＋ type and fall into area I. The trend is the same as evaluated over the last two years.