Effects of hydrogeological properties on sea-derived benzene transport in unconfined coastal aquifers

Wei Ci Li, Chuen Fa Ni, Chia Hsing Tsai, Yi Ming Wei

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

This paper presents numerical investigations on quantifying the hydrodynamic effects of coastal environment factors, including tidal fluctuations, beach slopes, hydraulic conductivity, and hydraulic gradients on sea-derived benzene transport in unconfined coastal aquifers. A hydrologic transport and mixed geochemical kinetic/equilibrium reactions in saturated–unsaturated media model was used to simulate the spatial and temporal behaviors of the density flow and benzene transport for various hydrogeological conditions. Simulation results indicated that the tidal fluctuations lead to upper saline plumes (USPs) near the groundwater and seawater interfaces. Such local circulation zones trapped the seaward benzene plumes and carried them down in aquifers to the depth depending on the tide amplitudes and beach slopes across the coastal lines. Comparisons based on different tidal fluctuations, beach slopes, hydraulic conductivity, and hydraulic gradient were systematically conducted and quantified. The results indicated that areas with USPs increased with the tidal amplitude and decreased with the increasing beach slope. However, the variation of hydraulic conductivity and hydraulic gradient has relatively small influence on the patterns of flow fields in the study. The increase of the USP depths was linearly correlated with the increase of the tidal amplitudes. The benzene reactive transport simulations revealed that the plume migrations are mainly controlled by the local flow dynamics and constrained in the USP circulation zones. The self-cleaning process of a coastal aquifer is time-consuming, typically requiring double the time of the contamination process that the benzene plume reach the bottom of a USP circulation zone. The presented systematic analysis can provide useful information for rapidly evaluating seaward contaminants along a coastal line with available hydrogeological properties.

Original languageEnglish
Article number307
JournalEnvironmental Monitoring and Assessment
Volume188
Issue number5
DOIs
StatePublished - 1 May 2016

Keywords

  • Beach slopes
  • Benzene transport
  • Numerical model
  • Tidal fluctuations
  • Upper saline plume (USP)

Fingerprint

Dive into the research topics of 'Effects of hydrogeological properties on sea-derived benzene transport in unconfined coastal aquifers'. Together they form a unique fingerprint.

Cite this