| Summary: | 碩士 === 國立高雄海洋科技大學 === 海洋環境工程研究所 === 96 === Dian Bao River is one of the major five rivers in the Kaohsiung County, where there was developed metal industry along both banks of the river. However, some unworthy metal mill owners discharged industrial wastes into the river by stealth, resulting in poor water quality, and thus the department of environment protection has focused on renovating this river. This research has planned for 19 sampling points since June, 2006, and used inductively coupled plasma optical emission spectrometer (ICP-OES) to analyze the content of 48 metal elements in the water and sediment, in order to understand the situation of trace element pollution in the Dian Bao River.
The research results indicated that most of the water quality analysis items could meet the standards set by law. The average concentration of total Fe (1.4±0.716 mg/L) and total Mn (0.27±0.184 mg/L) were the highest. Wherein, the total B concentration in the 4 observation stations at the Dian Bao Bridge exceeded Effluent Standards. At the observation station near National Kaohsiung First University of Science and Technology, the total concentration of Zn (0.61 mg/L) exceeded Surface Water Classification and Water Quality Standards. It was found in the result of the long-term (68 times through four seasons in a year) fixed sampling, that the pollution concentration of total As, total B, and total Zn from the observation station at the Dian Bao Bridge was obviously higher than that at the Ciao Zih Tou Bridge, which indicated that the pollutant source was at the place between the Dian Bao Bridge’s upper reaches and the Ciao Zih Tou Bridge. The comparison of the concentration of total Cr, total Cu and Ni, total Fe, total Pb, and total Mn indicated that the potential sources came from the upper reaches of Ciao Zih Tou Bridge.
The result of correlation statistic analysis indicated: a high-level and notable positive correlation (r>0.69, P<0.01) was evident among (1) the total B, total Cr and total Cu, (2) total Ni and total As, and (3) total Fe and total Zn. The metals with high correlation between each other probably came from the same pollutant source. The significance of metallic pollution in the water could be divided into three clusters according to the result of spatial distribution and cluster analysis, that is, (1) Wu Shan Bridge to Fong Shan Cuo Bridge at the upper reaches; (2) Fu An Bridge, considered as a cluster itself; (3) a cluster consisting of 11 observation stations. The area with the most serious pollution happened at the second cluster, belonging to the tidal reaches at the lower reaches.
The highest average concentration of each heavy metal in the sediment was observed at the Fu An Bridge river section; wherein the highest concentration of total Zn at the Fu An Bridge observation station was 1740 mg/kg dry wt, 2.9 times higher than the standard value regulated by the Soil and Groundwater Pollution Remediation Act; in addition, the highest concentration of total Ni, 645 mg/kg dry wt, was tested at the Bao Si South Street observation station at the Fong Shan Cuo branch, which was 3.2 times higher than the standard value regulated by the Soil and Groundwater Pollution Remediation Act.
The vertical distribution of total heavy metal concentration in the sediment at the Fu An Bridge reached its maximum value at about the 40 cm depth, and there was an obvious correlation between the concentration and the content of organic matter in the sample. Although the sediment concentration had a positive correlation with the particle diameter, it was not as obvious as that with the content of organic matter, which indicated that the content of organic matter was the main controlling factor of heavy metal accumulation. In addition, the cluster analysis based on metallic concentration could result in three kinds of clusters.
The sediment principle component analysis showed that, the component one consisted of Cr, Cu, and Zu, corresponding with the result of correlation analysis; the component two consisted of Ni, and the principle component three consisted of Pb, both of the components could explain 97.36% of the variations. The component one and two were probably related to the different types of metal industry at this drainage basin, whereas no correlation was found between the principle component three and the metal processing industry.
The sediment heavy metal enrichment factor analysis at the Dian Bao Stream indicated that it was better to calculate the enrichment factor based on the Dian Bao Stream background concentration than that by the crustal average concentration, in order to better match the actual situation. The enrichment factors of total Cr（0.9~3.5）, total Cu（0.7~3.9）, total Ni（1.0~22.1）, and total Zn（1.5~17.0）all supported that enrichment effect in part of the observation stations within that drainage basin, especially for Zn.
By comparing with 12 domestic and foreign rivers, it was found that the heavy metal pollution in domestic rivers was more serious than that in foreign rivers. There was severe pollution by all heavy metals except the total Cu and total Pb, which should draw attention from relevant entities. Compared with domestic and overseas laws in this regard, the total Ni and total Zn at Dian Bao River has exceeded several standards regulated by law, and the total Ni concentration was 5.7 times higher than the value regulated by the US NOAA TEL, and therefore relevant entities shall keep their eyes on and keep monitoring this problem, and try to develop a sound pollution prevention strategy.
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