河川持續與其週遭的滯水區與伏流層交換水體與溶解性化學物質，解析解常用來更清楚的了解與預測河川中污染物的傳輸與宿命行為。描述受滯水區影響的河川中污染物的傳輸的常用描述方法為瞬時儲蓄模式(transient storage model，簡稱TSM)，瞬時儲蓄模式假設滯水區與河道間的一階反應的質量交換。另一更精進的模式為所謂的伏流層擴散模式(hyporheic diffusion model，簡稱HDM)，伏流層擴散模式假設滯水區與河道的質量交換為擴散主控且遵循Fick定律。雖然文獻中已存在一些瞬時儲蓄模式與伏流層擴散模式的解析解，但並無可用於衰變性與降解性污染物的多物種傳輸的解析解，多物種傳輸解析解為同時描述瞬時儲蓄模式與伏流層擴散模式的衰變性與降解性污染物母物種與子物種的傳輸行為非常有效工具，常見的衰變性與降解性污染物包括有毒的稀有元素、放射性核種、工業用溶劑、殺蟲劑、養份與藥品等可能產生一系列一階或擬一階衰變或降解鏈鎖反應的各種來自天然過程與人為活動的污染物。本計畫為兩年期計畫，計畫目標為發展全新的瞬時儲蓄模式與伏流層擴散模式的多物種傳輸解析解以描述具滯水層與伏流層的河道衰變性與降解性污染物的傳輸，在進行的研究計畫團隊已發展一系列不同邊界條件的瞬時儲蓄模式的多物種傳輸的解析解。做為目前執行計畫的延續研究計畫，計畫目標為發展一系列不同邊界條件的伏流層擴散模式多物種傳輸的解析解，整合兩年計畫的成果可系統性建立相關解析解模式庫。 ;In rivers there is continuous exchange of water and dissolved chemicals with their surrounding stagnant water zone and the hyporheic zone. Analytical models are widely used to obtain a better understanding and make accurate predictions of the transport and fate of contaminants in rivers. One approach for modeling mass exchange of dissolved chemicals between the river channel and the stagnant zone is the transient storage model (TSM) in which the first-order reaction mass transfer between the river channel and stagnant water zones is assumed. A more refined approach is the so-called hyporheic diffusion model (HDM) where mass transfer from the river channel into the stagnant water zones or more generally the entire hyporheic zone is assumed to be controlled by diffusion and the Fick’s law is followed to describe solute diffusion. Although some analytical solutions for the TSM and HDM have already been reported in the literature, analytical solutions for TSM and HDM for the transport of multiple species in rivers have not yet been developed. Such solutions for TSM and HDM would be effective tools for simultaneously and more accurately predicting the transport behavior of both the parent species and the daughter species of degradable or decaying contaminants in rivers. These degradable or decaying constituents may contain a wide spectrum of contaminants resulting from specific natural processes and anthropogenic activities such as toxic trace elements, radionuclides, industrial chlorinated solvents, pesticides, nutrients and pharmaceuticals which generally involve a more complicated series of first-order or pseudo first-order decay or degradation chain reactions. In this two-year project we aim to develop novel analytical solutions for TSM and HDM for the purpose of describing the transport of degradable and decaying contaminant in rivers with stagnant water and/or hyporheic zones. In the on-going research of this two-year project, we have already derived a series of analytical solutions for TSMs subject to different types of boundary conditions. As a subsequent research of an on-going MOST project, this project attempts to develop novel analytical HDM solutions for describing the movement of degradable and decaying contaminant in rivers. A solution library will be systematically constructed by integrating the achievements of these two-year tasks.
