含氯有機化合物與放射性核種等物質造成的地下水污染問題，為現今非常重要的水資源議題，這些釋放到地底下的污染物常會造成環境與健康的危害，因此了解污染物在地下含水層水中的傳輸與遷移是非常重要的。此污染與傳輸的過程常會包括複雜的機制與情境。在場址中，污染的初始濃度常會因污染源質量的消耗或整治而隨時間而改變。此外，降解反應的過程常會是具複雜的分岐反應途徑，像是三氯乙烯就有可能同時產生三個不同二氯乙烯異構物。這些複雜的情況與反應機制都將造成模擬預測及整治評估的工作更加艱鉅。以移流-延散方程式為主的多污染物傳輸解析解已被廣泛用來描述這些具降解性污染物與其產物在地底下環境中的傳輸移動。然而，過去所發展的多污染物傳輸解析解模式大都假設入流邊界污染源的濃度為定濃度的釋放，且所考慮的降解反應過程常簡化為直鏈的降解反應，也就是無法考慮具複雜的發散或收斂反應途徑所產生的異構物與其不同的物化特性。本研究主要就是發展全新的三維地下水多污染物傳輸解析解模式。此發展的新解析解可同時考慮不同隨時間變化的污染源函數與複雜的降解反應途徑，將可更真實的描述場址中污染傳輸的過程。透過系統中所建立的控制方程式與對應不同時間函數的邊界條件，經由連續三個積分轉換及逆轉換來求得全解析解。接著藉由數值解與存在相關的半解析解模式，來驗證所推導的解析解與所撰寫的FORTRAN程式計算的正確性。此發展的模式將會用於評估過去模式的適用性，接著分別探討不同時變函數與降解反應途徑對於污染團遷移的影響，並進一步用於污染場址參數的推估、未來污染團的預測以及評估健康風險的危害。 在未來，可藉由所發展模式高運算效率的優勢，結合蒙地卡羅模擬以隨機產生多組的輸入參數，發展成機率式模擬的預測軟體，對於場址中參數常具不確定性下的模擬預測與整治評估更具實用性。另外也可將所發展的最新解析解模式進一步與圖形使用者介面結合，不僅能供產業人員更方便的應用於場址的整治及健康風險的評估，且可大大提升模式之附加價值，期望能成為廣為使用的軟體。 ;The groundwater contaminated by chlorinated organic compounds or radionuclides is a problematic water-resource issue worldwide. The release of these contaminants into the groundwater cause a major threat to the environment and our human health, and thus it is needed to understand the existing contaminants and their transport into the groundwater system. These contamination and transport processes include complex mechanisms and many different scenarios. The initial concentration of contaminants in the subsurface may change with time due to the remediation or depletion of the source zone. Moreover, the process of degradation of the contaminants also follows a complex reaction pathway, as the trichloroethylene may react and become three dichloroethylene isomers. These complex conditions and processes cause challenges for simulating and assessing the remediation of contaminated sites. Analytical solutions to multispecies transport based on advective-dispersive transport equations have been widely used for simulating the movement of the originally released parent contaminant and its degradation byproduct in the subsurface environment. In most previous studies, the multispecies transport analytical models in previous study have often been simplified for only a constant source concentration and a straight decay chain, neglecting the divergent and convergent reaction pathways, including the individual properties of the isomers. This study is aimed to obtain newly analytical solutions that can simulate the multi-dimensional reactive transport of multiple contaminants in the subsurface. These newly derived analytical solutions can consider the complex reaction pathways associated with different types of time-dependent source functions to give a more realistic description of reactive transport at contaminated sites. Three integral transformation techniques are used to derive the exact analytical solutions to the governing equations system subject to different time-dependent inlet source functions. The computer code is developed in the FORTRAN language and the accuracy of the derived analytical solutions is examined for several cases using numerical solutions and existing semi-analytical model. The developed models are then used to assess the performance of previously developed models and also to investigate how the source functions and complex reaction pathways affect to the transport behavior of multiple contaminants in soil-water systems. The developed analytical models are also used to provide parameter estimations, future plume migration prediction, and health risk assessment at real sites. The high computational efficiency of the developed models makes them suitable for generating stochastic parameters and executing a large number of simulations by using the Monte Carlo technique for future applications at contaminated sites which have parameters with high degrees of uncertainty. Moreover, the developed model can also be used to design a user friendly graphical user interface (GUI), which coupled with the transport and risk assessment models will make it easier to simulate remediation and assessment at contaminated sites. This can greatly enhance the added value of the model, hopefully making it a popular software tool for this purpose.
