Examining the effectiveness of oiled ballast water treatment processes: insights into hydrocarbon oxidation product formation and environmental implications†

Abstract

Ballast water released from ships into coastal environments has been identified as a mechanism that introduces contaminants of concern into coastal ecosystems. This study investigates the treatment processes employed at a ballast water treatment facility in Valdez, Alaska, that remove hydrocarbons from unsegregated ballast water. Specifically, the aim is to quantify and characterize hydrocarbons of emerging concern, known as dissolved hydrocarbon oxidation products (HOPs) and heavy metals (HMs), throughout the treatment process. Specialized analytical techniques were employed, such as non-volatile dissolved organic carbon analysis, fluorescence spectroscopy, Fourier transform-ion cyclotron resonance-mass spectrometry, and inductively coupled plasma triple quadrupole mass spectrometry. Results demonstrate that the treatment removes benzene, toluene, ethylbenzene, and xylene (BTEX) compounds, while HOPs remain. Optical and molecular analyses provide insights into the composition and transformation of HOPs, showing a shift towards more oxygenated and complex compounds during the treatment process. Quantitative analysis of 18 HMs revealed a decrease in the concentration of most dissolved HMs throughout the treatment process, with none exceeding regulatory limits. The findings highlight the need for comprehensive monitoring and regulation of ballast water treatment processes, considering the presence of HOPs and HMs. The results provide valuable insights for environmental monitoring and risk assessment in ballast water treatment, emphasizing the significance of understanding and mitigating the impacts of petroleum derived contaminants on aquatic ecosystems.