| 英文摘要 |
The aim of this project was to properly understand the changing trend of water quality in those types of water bodies over the passage of time by monitoring the water quality of rivers, beach, oceans, reservoirs and groundwater in the 5 counties located in the central part of Taiwan.
Water quality was assessed by 72 water-monitoring stations along 19 rivers and affiliated branches, which monitoring was conducted once every month. The results showed that in central Taiwan, most of monitoring stations (about 85%~98%) were categorized to non(slightly)-polluted level in the Shihu river Basin, besides, the highest ratio of monitoring stations (about 25%~53%) categorized to severely-polluted level was observed in the Sin Huwei River Basins.
The river channel in some waterways consisted of loose gravel so rain water runoff led to a higher level of suspended solids in the waters, which examples include the Da-an River, Wu River, Jhuoshuei River, Sin Huwei River and Beigang River basins. The better water quality from the rivers north of the Dajia River Basin (upstream) can be observed, which may resulted from good weather conditions, however, the down stream monitoring showed that accumulation of pollutants was observed, which may resulted from the discharge of industrial effluent and household sewage.
The sea water quality monitoring consisted of 23 monitoring stations located in Class-A and Class-B marine environments, which monitoring was conducted once every season. There was a significant variation of water quality can be observed in the monitoring stations which placed near terrestrial discharge sources, however, overall water quality was similar to the previous reported results in recent years.
The beach water quality consisted of 1 monitoring station, which were monitored once per month from June to September. The findings from West-Ocean Educational Sea World beach was classified, the results showed that not only the water quality was normally excellent but also the highest ratio was classified as “Good” category.
The groundwater quality monitoring was conducted through 108 wells spread across 5 counties in past years. For general monitoring items except volatile organic compounds (VOCs), the 19 monitoring wells among the total ones were conducted once every season, other 35 monitoring wells were conducted once every 6 months, the other 54 monitoring wells were conducted once a year, respectively; however, as for VOCs, which was monitored once a year for total 108 wells.
The results showed that the main findings including ammonia nitrogen, iron, and manganese, exceeding groundwater Class-B monitoring criteria were similar as previous reported results in recent years. Ammonia nitrogen readings from monitoring wells in Changhua County and Yunlin County were higher than that from other regions. Moreover, the groundwater monitoring of VOCs showed that a slight concentration of chloroform, toluene and methyl-tert-butyl ether was measured within only 4 wells, which did not exceed the second category groundwater pollution control standard. Eventually, the water quality of each monitoring wells was evaluated by means of both Stiff diagram (Stiff pattern) and Piper diagram, which exhibited a consistent trend for the changes of each season.
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