| 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. Furthermore, these data can provide information for the Environmental Protection Organization to devise a pollution control policy by evaluation and analysis for the pollution of all water bodies.
The 73 water-monitoring stations spreading among the 19 rivers were established, and the water quality was monitored once per month. The data obtained of this year showed that there were 67.3% stations categorized to non(slightly)-polluted level, including the Houlong River, Sihu river, Da-an River and Dajia River Basins, which consisted of relatively superior water quality; on the contrary, there were many stations (higher ratios than other basins) categorized to moderately- or severely-polluted level, including the Lugang River, Sin Huwei River and Beigang River Basins. As for the rivers in the central Taiwan, the water quality of the upstream was generally superior, while the higher ammonia nitrogen concentrations of the downstream were observed.
In the central Taiwan, a relatively high accumulative precipitation from May to September was observed than in other months during this year. However, the riverbeds were washed away, resulting in slightly higher concentrations of suspended solids in some rivers, such as the rivers in the basins of Da-an River, Dajia River, Wu River, Jhuoshuei River, Sin Huwei River and Beigang River, the worse water quality was observed. Because of geological characteristics in the Jhuoshuei River Basin, the color of water may be grey and murky on regular days. In 2012, there were 44.4% non(slightly)-polluted (the highest ratio in the category) and 38.5% moderately-polluted level (the second high ratio in the category) stations in central Taiwan, respectively.
In terms of water monitoring of sea area, there were four coastal seas monitored once every season. The coastal water quality of offshore Hsinchu Xiangshan, Taichung Harbor and Changpin Coastal area (Changhua) was classified as Class-B marine environment water body, and that of offshore Yunlin was classified as Class-A ones, respectively. The monitoring results during this year showed that the most findings can meet the marine environment quality standard for categorized seawaters, except in the fourth quarter, the dissolved oxygen item of all stations spreading offshore Hsinchu Xiangshan and the Da-an River mouth station in Taichung Harbor coastal area could not meet the Class-B marine environment quality standard.During the first and second seasons of monitoring, the relatively higher values of suspension solids in some parts where in the waters south of the Changpin coastal area (Changhua) were observed, which were the highest values measured in years. To sum up, the water quality in the second and third seasons was better than that in the first and fourth seasons, the findings were similar to past years.
Water quality of two beaches, including Qiding and West-Ocean Educational Sea World was monitored during this year. The monitoring by five times during this year showed that the ratio of water quality classification for both these beaches was 60%, which was classified as "Good" category. The rapid changes of water quality of these beaches were observed, which may result from rainfall and merging river flows.
The water quality of eight reservoirs was monitored once every season. The respective monitoring results showed that not all items met the water quality criteria of Class-A.
In terms of the eight reservoirs in central Taiwan, the water quality of the Jih-Yueh-Tan Reservoir showed that the ratio of which was classified as oligotrophe and mesotrophe were 75% and 25%, respectively. Secondly, the ones in the Yung-Ho-Shan Reservoir and Te-Chi Reservoir were 50% and 50%, respectively. Similarly, those of which was classified as oligotrophe and mesotrophe in the Wu-She Reservoir were 33% and 67%, the ones in the Li-Yu-Tan Reservoir were 25% and 70%, respectively. Specially, the water quality in the Ta-Pu Reservoir was classified as mesotrophe. Eventually, the ratio which was classified as mesotrophe and eutrophe of Ming-Te Reservoir and Tou-She Reservoir were 75% and 25%, respectively.
The groundwater quality monitoring was conducted through 97 wells spread across five counties. The results obtained during this year showed that the main findings including ammonia nitrogen, iron, and manganese, exceeding groundwater Class-B monitoring criteria were similar as those reported in previous years. Moreover, the monitoring of volatile organic compounds in the groundwater showed that there was only one well exceeded the second category groundwater pollution control standard of trichloroethylene and cis-1, 2-dichloroethylene, respectively. The overall ammonia nitrogen concentrations measured in wells of central Taiwan in Changhua County and Yunlin County were higher than those in other counties. According to the assessment of water quality of all monitored wells, the highest percentage was 64.5% for Ca2+ and HCO3- using Stiff-plotting analysis. While the Piper-plotting method showed that there was 50.0%, the highest ratio, in Area I, the results were consistent with those conducted in the past years.
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