多物種解析解模式對於了解地下水中污染物之移動情形是有效的模擬工具，尤其是對於移動過程中會產生序列降解反應之有害物質，如含氯有機溶劑、放射性物質、殺蟲劑及農藥等；但多物種解析模式有其技術上的困難，在過去研究中並不常見。前人所提出的多物種解析模式皆使用瞬間平衡吸附之假設，此假設簡化了污染物在溶解相和吸附相之間的交換反應。然而，從過去文獻可以發現，限制速率吸附作用對於溶質傳輸有很大的影響，若將瞬間平衡吸附之假設套用在每個情況，則所得之污染物濃度分布情形及評估整治時間的結果會出現明顯的誤差。本研究之目的為發展限制速率吸附影響下之多物種溶質傳輸解析模式，以探討限制速率吸附對多物種溶質傳輸之影響。溶質傳輸方程式分別對第一類及第三類邊界條件進行求解，其解析解與數值解所得之結果非常吻合。透過吸附速率之敏感度分析，發現使用瞬間平衡吸附之假設會低估污染物的濃度，且隨著吸附速率越小所得之濃度也會越高。;Analytical models for multiple advection-dispersion equations sequentially coupled with first-order decay reactions provide fast and cost-effective tools for simulating the plume behavior of the parent and daughter species of decaying contaminants such as radionuclides, dissolved chlorinated solvents and nitrogen chain. However, only a few analytical solutions for coupled multispecies transport equations have been described in the literature. For mathematical simplification, all of the developed analytical models currently used to simulate migration of the decaying contaminants assume instantaneous equilibrium sorption between contaminants in the dissolved and sorbed phases. However, experimental and theoretical research results have indicated that rate-limited sorption could have a profound effect upon solute transport in the subsurface environment. By making the instantaneous equilibrium sorption assumption, the potentially significant impact of the rate-limited sorption cannot be considered or subjected to examination. In this study, we present an analytical model for describing the coupled multispecies transport of decaying contaminants subject to a rate-limited sorption process. The equations are solved for both the first-type and third-type inlet boundary condition. The newly derived analytical solutions are tested against the numerical solutions generated using the Laplace transform finite difference method. The comparison shows excellent agreement with the numerical solutions, demonstrating the correctness of the developed analytical model and the associated computer code. The solutions are then used to assess the influence of the rate-limited sorption on the coupled multispecies transport of the decaying contaminants. Results show that simulations using rate-limited models predict higher concentrations than those obtained with the equilibrium-controlled model.
