臺灣西北部觀音藻礁海岸重金屬含量分析

Heavy Metal Contents of Algal Reefs in Guanyin Coast of Northwest Taiwan

紅藻門之殼狀珊瑚藻類將海水中游離的鈣和碳酸鹽結合，形成固態的碳酸鈣，經不斷的膠結，而建造大型的生物礁體。因為人類長期對藻礁區生物組成和生態重要性的漠視，讓許多污染排入藻礁區，造成造礁藻類死亡，生態系也遭受破壞。本研究針對臺灣西北海岸生長狀況最佳的觀音藻礁區進行調查，範圍自小飯壢溪口南岸至新屋溪口北岸約2 km的海岸線，藻礁分布之寬度可達500 m，有些礁體厚度可達3 m，退潮時可明顯露出海平面1 m左右，利用X-射線螢光光譜儀來檢測樣本重金屬含量，於觀音藻礁區設置4條樣線，北海岸淺水灣藻礁區設2條樣線，作為對照組，護岸堤內土壤表層1處，共計採取115樣本，採用多變數分析之分類法及分布序列法，以定量數據來計算樣本之差異，綜合群團分析與主成分分析比較，可以確認幾項主要元素來進一步探討。同為藻礁結構，北海岸淺水灣與西北海岸觀音藻礁內重金屬濃度不同，低潮線與近岸區亦不相同。根據臺灣地區土壤重金屬含量標準與等級區分表，銅、鋅、鉻、砷的含量在西北海岸觀音藻礁偏高。鈣、鍶與礁體成分有關，北海岸淺水灣的鈣純度較高，鍶的含量在觀音藻礁略偏高。其中鈦、釷、鋯數值異常地高，對照北海岸的樣本，觀音藻礁應有外來的鈦、釷、鋯元素。

Some groups of marine algae, particularly calcareous red algae (Rhodophyta), absorb calcium ions from seawater and generate calcium carbonate in algal bodies, thereby forming large reefs. However, these algal reefs are little known in terms of their biological composition and ecological importance. Many pollutants are discharged into these habitats, causing algae death and destruction of the ecosystem. Guangyi, located in northwestern Taiwan, is in relatively better condition in terms of algae growth rate and coverage. The range of algal reef distribution is about two kilometers starting from the southern part of Hsiaofanli Creek and ending at northern outlet of Hsinwu Creek. The sizes of the algal reefs along those areas are about few to 500 meters wide and one to few meters in depth. To understand heavy metal contents of the algal reef areas, five sampling lines in Guanyin, northwestern Taiwan, and two sampling lines for controling in Qianshui Bay, north Taiwan, were sampled. In total, 115 samplings of 32 heavy metal contents were measured by X-ray fluorescence. Multivariate statistical analysis, classification and ordination were used for the quantitative analysis of the 26 heavy metal contents principal component analysis and cluster analysis. This has confirmed several main elements for discussion. Heavy metal contents of algal reef in the low tidal zone and near-shore areas were not the same. According to soil heavy metal content standards and classification of Taiwan, copper (Cu), zinc (Zn), chromium (Cr) and arsenic (As) concentration in samplings of Guanyin algal reef were at fifth grades, indicating pollutions. Calcium (Ca) is a reef composition element, and there is high purity calcium in Qianshui Bay, north Taiwan. Strontium (Sr), titanium (Ti), thorium (Th), zirconium (Zr) in reef algae of Guanyin, northwest Taiwan, were higher than the control samplings of Qianshui Bay, north Taiwan, indicating external sources of strontium, titanium, thorium, zirconium elements in Guanyin Coast.