| 摘要: | 為評估湖泊水庫、河川及海域水體發生優養化之可能性，只偵測水體總磷含量是不夠的，同時須瞭解底泥中各種鍵結態磷之含量，及各種鍵結態磷受底泥環境之變遷影響而造成之磷釋出。台灣地區為預防湖泊水庫等水源地發生優養化造成自來水中三鹵甲烷等致癌物濃度升高，因此每年或每季定時定點採集水樣監測水源地水質之總磷(TP)或正磷酸鹽(PO43－)含量變化。台灣地區對於河川及近岸海域亦只監測水域水質之總磷(TP)量變化，對於會不斷釋出或吸附累積磷之湖泊、水庫、河川及近岸海域之底泥中總磷量則並未進行調查工作，更遑論底泥中以各種鍵結態形式存在之磷含量之調查數據，但國外則很重視底泥中各種鍵結態磷含量之變化，且各種分析鍵結態磷含量之化學分析方法已被廣為提出討論。尤其底泥磷之鍵結型態間之轉移會受到底泥特性、底泥好氧或厭氧狀態之影響。如同底泥中重金屬總量未能代表底泥之生物毒性及危險性，底泥之總磷量不能代表水中植物可吸收生長之磷量，或水體是否會發生優養化之判斷依據。因此本研究擬針對南部遭受嚴重工業、農業及家庭廢水污染之三條河川(二仁溪、三爺宮溪、及鹽水溪)底泥進行各種鍵結態形式存在之磷含量調查(包括溶解反應性磷量，Soluble reactive phosphorus, SRP)、探討底泥環境條件改變如含氧量變化等對各種鍵結態形態磷含量之影響、底泥沖刷進入海域遭受各種濃度鹽度時，各種鍵結態形式磷含量之轉移及釋出，期望建立本土化之底泥中各種鍵結態磷在環境中之流佈宿命，藉此預測水域發生優養化之機率。本計畫擬分三年執行。第一年擬將底泥中磷依SEDEX法分成五種鍵結型態，收集以SEDEX法萃取之各鍵結態磷溶液，分析與磷同時萃出之重金屬(Simultaneously Extracted Metals with Phosphorus, SEMP) (鐵、錳、鋁、鈣、鋅、銅、鉛、鎘、鉻、鈷、及鎳)，以原子吸收光譜儀(AAS)分析重金屬含量，計算每克底泥中可與各種鍵結態磷同時溶出之重金屬含量。將探討底泥中各種鍵結型態磷在不同污染程度河川、不同深度河川底泥中之分布，配合歷年環保署河川水質監測站分析之河水中正磷酸鹽及總磷含量，進行不同深度底泥中磷與水體中磷量相關性分析。另採用統計之主成份分析法推測河川底泥各種鍵結態磷之來源及轉移。分析不同粒徑底泥中各種鍵結態磷之含量，探討顆粒粒徑與各種鍵結態磷含量之相關性。第二年於實驗室進行環境因素改變，如河水及底泥溶氧量、pH值、氧化還原電位(ORP)、及溫度等影響河水中磷含量、河水中重金屬含量、底泥中各種鍵結態磷分佈、及底泥中同時與磷萃出之重金屬量(SEMP)；另以批次試驗探討好氧及厭氧微生物生長，對各種鍵結態磷遷移之影響。第三年於實驗室進行批次試驗，採二仁溪、三爺宮溪、及鹽水溪底泥添加各種鹽度之人工海水，探討底泥中磷之釋出能力及各種鍵結態磷之互相轉移受水體離子強度之影響。
The monitoring of total phosphorus (TP) concentration in water quality is not enough to assess the occurrence of eutrophication in lakes, reservoirs, streams, and coastal area. The realization of phosphorus species concentration in sediment and the environmental factor affecting the release of phosphate are important. To prevent the increase of carcinogen haloform concentration in tap water, the variation of TP and orthophosphate (PO43－) was monitored per season or year in Taiwan. Among the phosphorus species, the TP was the only monitored water quality parameter for streams and coastal area of Taiwan. However, TP concentration in sediment of lakes, reservoirs, streams, and coastal area did not investigate yet, still less the fractionated phosphorus (P) data of sediment which will release or accumulate P. Phosphate phases may undergo significant changes with geochemical characteristics, aerobic and anaerobic condition of sediment over a short period of time. The assessment of biological risk and toxicology from sediment could not represent by the total concentration of heavy metals involved. Similarly, total amount of P contained in sediment did not equalize the available amount of P for the phytoplankton growth, or justify the occurrence of eutrophication. The main objective of this study was to describe the fate of phosphorus species, including soluble reactive phosphorus (SRP), along the streams of southern Taiwan and to predict the eutrophication in lakes, streams and coastal area. Chemical extraction methods was used to fractionate phosphorus encountered in suspended solid, water, and sediments of the Er-ren, Sanyehkung and Yan-shuei rivers which had been heavily polluted with industrial, agricultural and domestic waste water. The environmental composition of river sediment were systematically determined to assess the phase transformations, release and re-adsorption or re-precipitation of phosphate speciation, in particular dissolved oxygen, pH, redox potential as well as ionic strength encountered when the sediment was flushed into coastal area. This proposal will be divided into three years. In the first year, the river sediment will be separately quantified into five sedimentary phosphate species: loosely sorbed P; ferric iron-bound P, authigenic carbonate fluorapatite+ biogenic apatite + CaCO,-associated P; detrital apatite P; and organic P by sequential extraction method (SEDEX). The amount of simultaneously extracted metals (Fe, Mn, Al, Ca, Cu, Pb, Cd, Cr, Co, and Ni) with phosphorus (SEMP) was analyzed with atomic absorption spectrometry (AAS). The correlations between fractionated P/SEMP were developed. The fractionated P from different polluted level of rivers, from different sizes of sediment particles, and from vertical profile of sediment will correlate with historic observation data of PO43－ and TP of river water quality from Taiwan EPA. The principle component analysis was used to predict the sources and transformation of fractionated P. Major environmental factors in stream sediment, including dissolved oxygen, pH, redox potential (ORP) and temperature are studied in the second year’s proposal, which will affect the mobilization of phosphate and heavy metal ions from sediment into water phase, the transformation of fractionated P and SEMP. In this study, the sediments from a river are exposed to different microorganism loads under oxic or anoxic batch reactor to realize the mobilization of different P fractions. In the third year’s proposal, different salinities of artificial sea water was mixed with sediments collected from Er-ren, Sanyehkung and Yanshuei rivers to detect the mobilization of P from sediment matries under ionic strength effects. |
