Groundwater pollution by organic compounds: a three-dimensional boundary element solution of contaminant transport equations in stratified porous media with multiple non-equilibrium partitioning

✍ Scribed by Elzein, Abbas H.; Booker, John R.

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 520 KB
• Volume: 23
• Category: Article
• ISSN: 0363-9061
• DOI: 10.1002/(sici)1096-9853(19991210)23:14<1733::aid-nag992>3.0.co;2-l

✦ Synopsis

Industrial contaminants and land"ll leachates, particularly those with high organic content, may migrate into groundwater streams under conditions of non-equilibrium partitioning. These conditions may either be induced by time-dependent sorption onto the soil skeleton and intra-sorbent di!usion in the soil matrix, or by heterogeneous advective "elds within the pore. These processes are known as chemical and physical non-equilibrium processes respectively, and may result in signi"cant deviations from the paths predicted by steady-state partitioning assumptions. In addition, multi-directional soil properties, soil strati"cation and complex geometries of the pollution source may require a full three-dimensional analysis for accurate contamination prediction.

A three-dimensional boundary element solution of the time-dependent di!usive/advective equation in non-homogeneous soils with both physical and chemical non-equilibrium processes is developed. Saturated conditions and rate-limited mass transfer are assumed. The Laplace transform removes the need for time-stepping and the associated numerical complexity, and the use of Green's functions yields accurate solutions of in"nite and semi-in"nite domains such as soils as well as media with "nite dimensions. The solution requires boundary discretization only and can therefore be a valuable tool in bio-remediation and land"ll design where di!erent geometries, soil properties and pollutant loads may be analysed at low cost. The proposed technique is validated by comparing its predictions to analytical solutions obtained for di!erent types of soil and contaminant sources. The scope of the method is illustrated by analysing the contamination of multi-layered soils by a neighbouring river and a surface source.