Laser-induced fluorescence logging as a high-resolution characterisation tool to assess LNAPL mobility

Jonás García-Rincón; Evangelos Gatsios; John L Rayner; Robert G McLaughlan; Greg B Davis

doi:10.1016/j.scitotenv.2020.138480

Laser-induced fluorescence logging as a high-resolution characterisation tool to assess LNAPL mobility

Sci Total Environ. 2020 Jul 10:725:138480. doi: 10.1016/j.scitotenv.2020.138480. Epub 2020 Apr 4.

Authors

Jonás García-Rincón¹, Evangelos Gatsios², John L Rayner³, Robert G McLaughlan⁴, Greg B Davis⁵

Affiliations

¹ CSIRO Land and Water, Private Bag No. 5, Wembley, WA 6913, Australia; Faculty of Engineering and Information Technology, University of Technology Sydney, 15 Broadway, Ultimo, NSW 2007, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Australia. Electronic address: Jonas.Garciarincon@csiro.au.
² CSIRO Land and Water, Private Bag No. 5, Wembley, WA 6913, Australia; Faculty of Engineering and Information Technology, University of Technology Sydney, 15 Broadway, Ultimo, NSW 2007, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Australia. Electronic address: Gatsios@exelia.gr.
³ CSIRO Land and Water, Private Bag No. 5, Wembley, WA 6913, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Australia. Electronic address: John.Rayner@csiro.au.
⁴ Faculty of Engineering and Information Technology, University of Technology Sydney, 15 Broadway, Ultimo, NSW 2007, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Australia. Electronic address: Robert.McLaughlan@uts.edu.au.
⁵ CSIRO Land and Water, Private Bag No. 5, Wembley, WA 6913, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Australia; School of Earth and Environment, University of Western Australia, Nedlands, WA, Australia. Electronic address: Greg.Davis@csiro.au.

PMID: 32298881
DOI: 10.1016/j.scitotenv.2020.138480

Abstract

High-resolution characterisation tools such as Laser-Induced Fluorescence (LIF) logging represent a step forward towards a more effective management of sites contaminated by light non-aqueous phase liquid (LNAPL) petroleum hydrocarbons. In this paper, the applicability of LIF response as an indicator of LNAPL mobility at one site with an unconsolidated aquifer was investigated. LIF profiles were logged adjacent to twin coring locations and wells with LNAPL transmissivity (T_n) measurements in a heterogeneous gasoline contaminated site in Western Australia. LIF response was correlated to T_n to a greater extent than LNAPL saturation (S_n) measurements from coring. In particular, LIF signal maxima were a better indicator of T_n than the integral LIF signal. Furthermore, LIF allowed rapid identification of areas with long-term near-immobile LNAPL (entrapped and residual) because of the multi-wavelength waveforms associated with distinct subsurface characteristics. It was also demonstrated that the delineation of presumably less-mobile intervals could be enhanced by using the relative LIF response in the 350 nm wavelength channel. Thus, this work gave evidence that LIF logging provides valuable information about LNAPL distribution and mobility in commonly found subsurface settings, despite generally poor correlations with S_n measurements. LIF probes can be successfully used to guide the installation and application of more costly conventional methods in addition to the development of existing site models.

Keywords: Conceptual site model; Environmental geophysics; High-resolution site characterisation; LIF logging; LNAPL transmissivity; Petroleum hydrocarbons.