| 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 five counties located in the central part of Taiwan.
Water quality was assessed by sixty-nine water-monitoring stations along eighteen rivers and affiliated branches, which monitoring was conducted once every month. The results showed that in central Taiwan, most of monitoring stations (about 98% ~ 100%) were categorized to non(slightly)-polluted level in the Shihu river Basin; on the other hand, the highest ratio of monitoring stations (about 32% ~ 37%) categorized to severely-polluted level was observed in the Beigang 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, Dajia, Wu River and Sin HuWei 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 twenty-three 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 one monitoring station, which was monitored once per month from June to September. The findings from West-Ocean Educational Sea World beach was classified, the results showed that the water quality was normally excellent, the highest ratio was classified as “Good” category.
The water quality of eight reservoirs was monitored once every season. The results indicated that there was the highest proportion of oligotrophic ratings for the water quality of the Jih-Yueh-Tan Reservoir, on the contrary, there was the highest proportion of eutrophic ratings for that of the Ta-Pu Reservoir. In addition, a significant increase of the Carlson trophic state index was observed in the Ta-Pu Reservoir, Te-Chi Reservoir, and Wu-She Reservoir, respectively, while the water quality changes of each season at the other reservoirs were within historical norms.
The groundwater quality monitoring was conducted through ninty-seven wells spread across five counties in past years, however, the other twelve wells which located in Nantou County were monitored additionally from the second quarter, 2014. Therefore, there are one hundred and nine monitoring wells in this program. The amount of twenty-five monitoring wells which was conducted once every season changed to forty-five wells (which were not all the same as above twenty-five wells), the rest monitoring wells were conducted once every six months, as for volatile organic compounds (VOCs), which was monitored once a year for total one hundred and nine 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 those from other regions. Moreover, the groundwater monitoring of VOCs showed that there was only one well exceeded the second category groundwater pollution control standard of trichloroethylene and cis-1,2-dichloroethylene, respectively. 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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