| 摘要: | 重金屬等底泥中物質自受污染底泥釋出到表面水體或被水中生物及底棲生物吸收代謝造成毒害，皆須透過孔隙水(pore water)做為中間傳輸介質。本研究計畫目的乃著重於探討底泥表面之水體，受季節雨量影響時，水中溶氧改變造成氧化還原電位(ORP)變化，此時對二仁溪不同深度底泥顆粒中重金屬等物質釋出到孔隙水中程度之影響。將探討之孔隙水中可能釋出物質包括硫酸根離子、磷酸根離子、硝酸根離子等將採用離子層析儀分析。鉛、鉻、銅、鋅、鎳離子等將採用石墨爐式原子吸收光譜儀分析，同時監測水體及孔隙水中之DO、ORP、pH值。預期實驗結果將有助於瞭解及推估重金屬在底泥顆粒及週遭孔隙水中的傳輸現象。對於建立國內底泥品質標準(Sediment Quality Criteria)，將有助益。
本計畫將以二仁溪底泥做為研究對象。採用新式之Sediment core採泥器(SOFIE)，採集未受干擾破壞合乎自然河川底泥物化特性之泥樣，帶回實驗室培養，改變表面水體之溶氧量後，偵測底泥中ORP等因子隨時間及深度之變化速度。本研究設備之特點為在不同深度泥層以特製PES孔隙水採樣測針，收集各種深度之孔隙水，減少受干擾之機會。分析由不同深度獲得之孔隙水中重金屬、陰離子、DO、pH、ORP等濃度，並以多變數統計分析方法（相關性矩陣）探求pH，ORP和孔隙水中各項物質濃度、重金屬濃度之相關性。結果顯示孔隙水中ORP和溶氧量、pH值、硫酸根、磷酸根、及硝酸根成明顯正相關，相關係數分別為0.76、0.96、0.96、0.6、及0.86。孔隙水中ORP和Cr、Cd、Zn、Cu、Ni離子濃度成明顯負相關，相關係數分別為-0.83、-0.86、-0.9、-0.79及-0.85。
The pore water act as the transformation medium for the remediation of heavy metal ions, sulfate ion, phosphate ion, and nitrate ion from contaminated sediment to invertebrates living in the river water. The purpose of this study is to realize the variation of oxidation reduction potential (ORP) on the remobilized concentration of heavy metal ions in the pore water at the influences of rain season. The chemical speciation discussed in pore water included lead, chromium, cupper, zinc, and nickel ions, which were determined with graphite atom absorption spectrophotometer. The study results will be useful for the prediction and assessment of transformation happened in the pore water in river sediment.
An modified Sediment or Fauna Incubation Experiment (SOFIE) was used to collected the Ell-ren river sediment which was not disturbed and preserved the natural quality of sediment in river. By the variation of dissolved oxygen concentration in surface water, the ORP will vary with sediment depth. For the reduction of interface, polyethersulfone (PES) was used as the probe to collect the pore water in different depth. The multivariate statistic method was used to realize the association of chemical speciation found in the pore water.
The correlation between ORP and concentrations of dissolved oxygen, pH, sulfate ion, phosphate ion and nitrate ion was positive significant (r=0.76, 0.96, 0.96, 0.6, and 0.86). The correlation between ORP and ions of Cr, Cd, Zn, Cu, and Ni found in pore water have negative significant correlation with coefficient r = -0.83, -0.86, -0.9, -0.79 and -0.85. |
