| 摘要: | 城市為人類長時間活動及居住之區域，街道揚塵因呼吸而進入人體，街塵中重金屬成份及濃度影響健康甚鉅。高雄市為南部重工業匯集之工業城，諸如：金屬冶煉業、造船業、石化業及重型機械等，可能導致城市街道中塵粒重金屬含量增加；為探討銅、鉛、鋅、鉻、鎳於高雄市街塵中累積分布狀況，依工業區、住宅區、商業區、碼頭區、遊憩公園區及背景區等合計規劃18個採樣點，於春、夏、秋及冬四季收集街塵，並將街塵分成四種粒徑範圍(小於0.074mm、0.074~0.297mm 、0.297~0.5mm、0.5~2.0mm)，使用火焰原子吸收光譜儀(flame atomic absorption spectrometry, FAAS)分析重金屬含量；另依連續萃取法分析街塵中五種鍵結態重金屬含量：可交換態(Exchangeable，F1)、碳酸鹽鍵結態(Bound to Carbonates，F2)、與錳氧化物鍵結態(Bound to Mn-oxides，F3)、與鐵氧化物鍵結態(Bound to Fe-oxides，F4)、以及與有機物鍵結態(Bound to Organic Matters，F5)。 銅、鉛、鋅、鉻及鎳主要蓄積於最小粒徑街塵(小於 0.074mm)，隨粒徑增加，重金屬含量減少；市區南側之臨近海邊工業區為主要重金屬污染源(鋅最高、鉛次之)、旗津造船廠及旗津渡輪站亦為重要污染來源(鋅最高、銅次之)；夏季盛行西南季風，可吹散市區南側高污染區街塵中鋅、鉛、鎳，飄散造成市區各地街塵中重金屬濃度升高；街塵中重金屬濃度分布為鋅>鉛>銅>鉻>鎳；夏季街塵中重金屬含量最高、次為秋季、其次為冬季、最低濃度出現於春季收集之街塵。街塵中90%以上銅主以有機態鍵結；鉛平均分散鍵結於可交換態、與碳酸鹽鍵結態、與鐵氧化物鍵結態、與錳氧化物鍵結態、以及與有機物鍵結態；鋅主以碳酸鹽鍵結態(可高達60%)，次為與錳氧化物鍵結；鉻主以鐵氧化物鍵結態存在(可高達65%)；鎳優先和鐵氧化物鍵結，次為與有機物鍵結。小於2 mm混合粒徑街塵中，旗津渡輪站發現最高銅濃度(300mg/kg)、巨蛋商區出現最高鉛濃度(250mg/kg)、臨海工業區及旗津渡輪站有最高鋅濃度(1052mg/kg)、臨海及大發工業區鉻量最高(50mg/kg)、鎳量次之約(14mg/kg)。人為污染造成高雄市區銅、鉛、鋅之最高累積增值倍數(Enrichment factors, EF)分別為55、10及8倍。
The concentrations of metals (Cu, Pb, Zn, Cr, and Ni) in street dust samples collected from 18 sites located in and around urban areas in Kaohsiung city, Taiwan, from October 2012 to April 2013, were determined by flame atomic absorption spectrometry (FAAS) after the modified sequential extraction procedure. Particles of street dust can be divided into four groups with diameter of < 0.074, 0.074-0.297, 0.297-0.5, and 0.5-2.0 mm, which were collected using a three-stage vibration shaker. Heavy metals in street dust were also fractionated into exchangeable, bound to carbonates, bound to Mn-oxides, bound to Fe-oxides, and bound to organic matters.The highest concentrations of heavy metals can be found in finest particle fraction (< 0.074mm), and decreased with increase of particle sizes. Over 90% of Cu bound with organic matters. Pb existed in five fractions with mean percentage. Zn primarily bound to carbonate fraction. Cr primarily bound to Fe-oxides fraction about 65%. Ni primarily bound to Fe-oxides, next bound to organic matters. The results of the analyses were used to determine major sources and magnitude of heavy metal pollution, and were compared with the background values. The highest concentration levels of zinc (Zn), lead (Pb), copper (Cu), chromium (Cr), and nickel (Ni) were found to be 1052, 732, 301, 50, and 23 mg kg-1, respectively. High concentrations of heavy metals were detected in south urban and close proximity to emission sources such as industrial and shipbuilding areas. Enrichment factors (EFs) as the criteria for examining the impact of the anthropogenic emission sources of heavy metals were calculated with background levels. The highest enriched elements were Cu, Pb, and Zn, about 55, 10 and 8, respectively in the street dust samples. EF values revealed that the sampling area was mainly influenced from four pollution areas, namely, Dafa, Kaohsiung Linhai, and Ren Da industrial parks, and shipbuilding areas. |
