| 摘要: | 針對重金屬與河川底泥的鍵結型態可分成六種鍵結型態：可交換態、與碳酸鹽鍵結態、與錳氧化物鍵結態、與鐵氧化物鍵結態、與有機物鍵結態及殘留態。為瞭解河川底泥中重金屬與四種地質化學成份間（碳酸鹽、鐵氧化物、錳氧化物及有機物）鍵結型態的強弱，本論文嘗試以數學模式關聯性表達四種地質化學成份與重金屬（銅、鎳、鈷、鉻、鋅及鉛）間之鍵結型態、並以Langmuir equation、Freundlich equation 及 Dubinin-Radushkevich equation（D-R equation）等溫吸附模式來解釋底泥中重金屬與四種地質化學成分間鍵結行為符合吸附模式。
為瞭解底泥與重金屬鍵結的吸附行為及數學模式關聯性，是否會受到河川重金屬污染濃度高低的影響，因此取兩條高濃度重金屬污染之河川（二仁溪及鹽水溪）底泥，四條輕度污染河川（曾文溪、急水溪、北港溪及朴子溪）底泥進行分析及數據計算。
結果顯示受污染嚴重之二仁溪及鹽水溪底泥中王水萃取重金屬含量會正相關於單位重量碳酸鹽中鍵結之重金屬量，符合線性相關數學模式；另四條重金屬汙染濃度低之河川底泥，除Zn外無存在明顯線性相關性。受高度污染底泥中每克錳氧化物中鍵結重金屬量對底泥中王水萃取重金屬含量存在明顯之正相關性，符合線性數學模式；輕度污染之曾文溪、急水溪、朴子溪及北港溪底泥中每克錳氧化物中鍵結重金屬量對王水萃取重金屬含量，除Zn外並無明顯正相關性。重金屬高度污染之底泥中王水萃取重金屬量與每克鐵氧化物中鍵結之重金屬含量呈指數型態正相關；輕度重金屬污染之四條河川底泥中與單位重量鐵氧化物鍵結之重金屬量對王水萃取重金屬量則為線性模式。高濃度重金屬污染之河川底泥中王水萃取重金屬（Zn, Cr, Pb, Cu, and Ni）與單位重量有機物鍵結之重金屬，具有明顯之半對數指數型態正相關。
相較於Langmuir equation 與Dubinin-Radushkevich equation（D-R equation）等溫吸附模式，Freundlich equation多層吸附模式可計算出最高之決定係數R2值，較適合於描述高濃度重金屬汙染河川底泥之六種重金屬對地質化學成分之鍵結，可視為一種吸附行為。低濃度重金屬汙染河川底泥計算出之決定係數R2值小，則不易以等溫吸附模式描述底泥之地質化學成分對六種重金屬鍵結行為。
The existence of heavy metals in river sediment could be divided into 6 forms: exchangeable, bound to carbonates, bound to manganese oxides, bound to iron oxides, bound to organic matters, and residuals. To realize the binding behavior between heavy metals (Cu, Ni, Co, Cr, Zn, and Pb) and geochemical components (Carbonates, Manganese oxides, Iron oxides, organic matters), different methematic models were used to express the relationship. Langmuir equation, Freundlich equation and Dubinin-Radushkevich equation (D-R equation) isothermal adsorption equations also used to fit the adsorption behavior.
Sediments collected from higher heavy metals contaminated rivers (the Yenshui, Ell-ren) and from lower heavy metals contaminated rivers (Tsengwen, Chishui, Potzu, and Peikang Rivers), located in southern Taiwan, existed different relationship between geochemical componenets and aqua-regia extractable heavy metals which were contaminated from industry, domestic, and agricultural wastewater.
The aqua-regia extractable heavy metals in the Yenshui and Ell-ren river sediment correlated linearly with heavy metal bound to per unit weight carbonates, and be expressed with linear empirical mathematic model. However, the linear correlations were not significant for the sediment collected from the Tsengwen, Chishui, Potzu, and Peikang Rivers which have lower heavy metals pollution, except Zn.
The correlations between aqua-regia extractable heavy metal and heavy metals bound to per unit weight manganese oxides in heavily polluted Yenshui and Ell-ren river sediment were significant and could be expressed as empirical linear model. However, the correlations in the Tsengwen, Chishui, Potzu, and Peikang Rivers were not significant, except Zn.
The aqua-regia extractable heavy metals (Ni, Co, Cr, Zn, and Pb) correlated well in exponential model and had positive significant correlation with metals bound to per unit weight iron oxides in the Yenshui river sediment. Similarly, the exponential correlations for Cu, Ni, Cr, Zn, and Pb in Ell-ren river sediment were high. The correlations between total heavy metal contents and heavy metals bound to per unit weight iron oxides in scarcely polluted river sediment could be expressed as empirical linear model.
The exponential correlation coefficient between aqua-regia extractable heavy metals (Co, Cr, Pb, Cu, and Ni) and metals bound to OM in per unit weight of OM were high in the Yenshui river sediment. The correlations at serious metal contamination river sediment can be defined in empirical mathematic model.
In description of the adsoption behavior of heavy metals into geochemical components of river sediments, the multilayer adsorption of isothermal Freundlich equation fitted well with higher coefficients of determination (R2) than those of Langmuir equation and Dubinin-Radushkevich equation (D-R equation).
錳氧化物 |
