The Challenge
Exhaust emissions from the combustion of heavy fuel oil (HFO) by ocean-going vessels have been suggested to increase risks to human health and the environment. In 2020, the International Maritime Organization (IMO) International Convention for the Prevention of Pollution from Ships (MARPOL) required vessels to comply with new air emission standards for sulfur which included the option to install Exhaust Gas Cleaning System (EGCS) which removes sulfur oxides emissions by spraying ambient seawater into the engine exhaust prior to release via the vessel’s stack. In an open-loop EGCS, the seawater is then collected and becomes a discharge from the ship. Washington State Department of Ecology (WDOE) expressed interest in understanding the potential effects of these discharges to marine ecosystems in the Puget Sound. This study originated from a cooperative agreement between the Port of Seattle, WDOE, and Cruise Lines International Association (CLIA). The focus of the agreement was to develop a program to perform a risk assessment following U.S. laws, WDOE standards and procedures, and recent IMO recommendations to better understand the potential impacts of EGCS discharges to the Puget Sound.
Our Solution
Senior staff at Spheros Environmental were vital in designing the ecological risk assessment. In addition to performing the field collection of all EGCS samples while the vessels were underway, which included six different cruise ships operating under two different engine loads for a total of twelve sampling scenarios. Our ecotoxicology laboratory in Port Gamble, Washington conducted whole effluent toxicity (WET) testing on each sample with three different species to aid in determining potential risk to marine organisms. In addition to the WET testing, 60 individual polycyclic aromatic hydrocarbons (PAHs) and 11 metals were measured at each sample point. These data were evaluated by comparing to ambient water quality standards, predicted no effects concentrations (PNECs), or by using the target lipid model for the PAHs. Impacts to the receiving waters were evaluated using the MAMPEC (Marine Antifoulant Model to Predict Environmental Concentrations) and Cornell Mixing Zone Model (CORMIX) models.
Prime
Results +What makes this unique
This study provided empirical data that was used to evaluate the potential risk of open-loop EGCS discharge to the marine organisms in the Puget Sound. The results of this study have been presented at International Maritime Organization (IMO) Marine Environment Protection Committee (MEPC) meetings and are still being used in international discussions related to EGCS use on large ships.
