Ensuring Appropriate Apportionment of PAHs in Sediments After an Oil Spill – AMOP 2018

Dr. Richards to present at AMOP

The Chemistry Matters team is excited to present at AMOP 2018.  The AMOP Technical Seminar on Environmental Contamination and Response is an international forum on preventing, assessing, containing, and cleaning up spills of hazardous materials in every type of environment, and is organized and sponsored by the Emergencies Science and Technology Section (ESTS), Science and Technology Branch of Environment and Climate Change Canada. Dr. Richards will present Ensuring Appropriate Apportionment of PAHs in Sediments After an Oil Spill.

Ensuring Appropriate Apportionment of PAHs in Sediments After an Oil Spill

Court D Sandau1,2, Lacey Harbicht1, and Phil Richards1

1 Chemistry Matters Inc., Calgary, AB, csandau@chemistry-matters.com

2 Statvis Analytics Inc., Edmonton, AB, court@statvis.com

Abstract:

After the chaos of dealing with the emergency component of any oil spill into a water environment, there comes the issue of monitoring for impacts and knowing what impacts are a result of the oil spill and what are from other sources.  Most oil spills end up with monitoring of polycyclic aromatic hydrocarbons (PAHs) as their sentinel chemical since they are persistent in the environment, there are readily available methods to detect PAHs in environmental matrices and there are techniques to fingerprint PAHs to determine their source.  The fingerprinting is important because PAHs are also ubiquitous and have multiple sources that drain into waterways resulting in background and anthropogenic patterns in the sediments in addition to those contributed from the oil spill.

There are several advanced statistical techniques that can be used to apportion PAHs in river sediments.  Tools using positive matrix factorization (PMF) have been developed by US EPA but are no longer being supported are still publicly available to use.  These techniques can be applied to PAHs from sediment data to allocate the source of the PAHs in the sediments to sources identified by the models.  Unfortunately, these models are not definitive and provide multiple conclusions depending on their starting point of the algorithm which can make interpretation difficult and sometimes questionable.

This presentation will provide a summary of PMF as well as some examples of Bayesian modelling in order to provide some guidance on model usage for PAH source apportionment for oil spills.  The models need to be applied conservatively and require chemistry interpretation to elucidate what end members have been identified by the model and if those end members make chemical sense.  The models will be applied to a real case study scenario looking at PAHs from a crude oil spill in a freshwater environment to illustrate how an effect, visual model using PMF can improve communication of complex results to multiple stakeholders.

Regulators and environmental professionals involved in oil spill monitoring will find this presentation applicable.