Migration of Cr₂O₇ ^2- and Butanone in Soil and Groundwater System After the Tianjin Port 8·12 Explosion

Abstract

After the Tianjin Port 8·12 explosion, an enormous amount of potassium dichromate (K₂Cr₂O₇) and butanone (CH₃COCH₂CH₃) leaked into the coastal soil–groundwater system, which potentially threatened the environment and human health. Determining the transport process of hazards is necessary to establish guidelines for remediating the contaminated area. This work aims to investigate the migration of potassium dichromate and butanone in the coastal soil‒groundwater system through a coupling unsaturated–saturated numerical model, incorporating the HYDRUS model into the MODFLOW/MT3D model. In the unsaturated zone, two-dimensional HYDRUS model was applied, and its recharge flux at the bottom boundary was utilized as the input of MODFLOW/MT3D model in the saturated zone. Results showed that Cr₂O₇ ^2- migrated much faster than butanone in the unsaturated zone and reached the water table in about 1 year. In comparison, butanone was unlikely to enter the aquifer even 5 years later with a migration depth of about 2.2 m. Driven by groundwater, the Cr₂O₇ ^2‒ that entered the aquifer migrated about 161 m toward southeast 5 years later. In the saturated zone, the contamination plume covered mainly the southeast area due to the groundwater flow direction.

Keywords

Potassium dichromate / Butanone / HYDRUS / MODFLOW / Coastal soil‒groundwater system / Tianjin Port 8·12 explosion

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