| 摘要: | 水體中磷主可區分為總磷(Total phosphorus , TP)、溶解反應性磷(Soluble reactive phosphorus, SRP)、溶解不可反應性磷(Soluble nonreactive phosphorus, SNP)、溶解有機態磷(Dissolved organic phosphorus, DOP)、溶解無機態磷(Dissolved inorganic phosphorus, DIP)、懸浮有機態磷(Particulate organic phosphorus, POP)、懸浮無機態磷(Particulate inorganic phosphorus, PIP)等。底泥中磷可依SEDEX法，分成可交換態磷(Exchangeable P)、與鐵氧化物鍵結態磷(Fe-bound P)、自生性磷灰石+碳酸鈣鍵結磷+生物性磷灰石(Authigenic apatite plus CaCO3-bound P plus biogenic apatite)、母岩碎屑中磷灰石+其他無機磷(Detrital apatite plus other inorganic P)、及有機態磷(Organic P)。水體中正磷酸鹽及總磷量，應用於評估水體發生優養化之可能性，但不足於通盤瞭解環境中磷循環；因此，為建構國內河川水體感潮流域環境，水體中完整之溶解態磷、懸浮態磷及底泥顆粒中各種鍵結態磷物種，受各種環境因素及生物吸收合成之影響而進行轉換之關聯性；本研究以受高度污染之三爺宮溪感潮河段底泥及河水，探討底泥受暴雨沖刷及浚渫再懸浮時，水體及底泥溶氧量、pH值、氧化還原電位(ORP)、鹽度梯度，以及停留於水體中天數等因素，造成水中溶解態磷、懸浮態磷與底泥中鍵結態磷之轉換。三爺宮溪感潮河段底泥各種鍵結態磷總量為677.76mg/kg，底泥停留於水體之時間越長，釋放至水體之懸浮態及溶解態磷量越多。水體環境由偏酸改變至偏鹼，底泥釋出至水中之總磷(TP)、總有機磷(TOP)、總無機磷(TIP)、總反應性磷(TRP)、總酸水解磷(TAP)、總溶解態磷(TDP)、溶解反應性磷(SRP)及總懸浮態磷量(TPP)等增加；隨PH自5.27增加至7.47，存在於自生性磷灰石+碳酸鈣鍵結磷+生物性磷灰石的磷(F3)含量百分比，自70%降至48%；存在於母岩碎屑中磷灰石+其他無機磷(F4)，自11%增至19%；存在於有機態磷(F5)，自6%增至19%。於厭氧環境下(-180至-201mV)，溶解無機態磷(DIP)、總溶解態磷(TDP)、溶解反應性磷(SRP)、總反應性磷(TRP)及總有機磷(TOP)釋出量高於好氧環境；相反地，水中總磷(TP)、總無機態磷(TIP)、總酸水解磷(TAP)、懸浮酸水解磷(PAP)及總懸浮態磷(TPP)，於好氧環境(約200mV)釋出量高於厭氧環境。底泥接觸各種鹽度海水，總反應性磷(TRP)、總無機態磷(TIP)及溶解反應性磷(SRP)，隨鹽度增加釋出量較多。
Phosphorus compounds can be separated into Total phosphorus (TP), Soluble reactive phosphorus (SRP), Soluble nonreactive phosphorus (SNP), Dissolved organic phosphorus (DOP), Dissolved inorganic phosphorus (DIP), Particulate organic phosphorus (POP), and Particulate inorganic phosphorus (PIP) etc. at aqueous phase. Using the SEDEX technique, P bounded in sediment was fractionated into five operationally defined phases with average paecentage: exchangeable P (8%), ferric bound P (3%), authigenic carbonate fluorapatite + biogenic apatite + CaCO3-associated P, detrital apatite P (45%), detrital P (21%) and organic P (23%). The orthophosphate and total phosphorus concentration did not supply enough information to predict P compounds transformation with environmental factors change in aqueous environment. This study focus to realize the P compounds existed primarily in the dissolved, particulate, and sedimentary phases which transformed by geochemical and environmental factors in estuary. The samples were collected from San-yeh-kong River. The P transformation between estuary water and resuspended sediment were also assessed and discussed with environmental factors, such as dissolved oxygen, pH, oxidation-reduction potential, salinity gradient, and retention time of sediment particles in the water etc. The concentrations of total organic phosphorus (TOP) were lower than those of total inorganic phosphorus (TIP), which consisted mainly of calcium-bound phosphorus (Ca-P). Moreover, the concentrations of total phosphorus (TP) in the river sediments were 677.76mg/kg; thus, the potential for the release of phosphorus compounds from the sediments to the water column and phosphorus bioavailability were still significant and increased with retention time. The release potential of TP, TOP, TIP, TRP, TAP, TDP, SRP, and TPP from sediment into aqueous phase increased in alkalinity than in acidity.Significant variations in the P forms with different pH sediment solution were observed. From pH 5.27 to 7.47, P bound to Ca (Ca-P) decreased from 70% to 48%. Percentage of detrital apatite plus other inorganic P increased from 11% to 19%. Percentage of organic P increased from 6% to 19%. Oxidation reduction potential also affected the release of P compounds from river sediment. The release amounts of DIP, TDP, SRP, TRP, and TOP were higher in anaerobic (-180 ~ -201mV) than in aerobic environment. In contrast, the release amounts of TP, TIP, TAP, PAP, and TPP were higher in aerobic (about 200mV) than in anaerobic environment. It was found that increased releases of TRP, TIP, and SRP occurred from 5? to 35? of salinities. The observed behaviour may be explained by salinity induced ion exchange with suspended sediment particles. |
