Method Development for Low-Concentration PAHs Analysis in Seawater to Evaluate the Impact of Ship Scrubber Washwater Effluents

Chih-Feng Chen,Chiu-Wen Chen,Frank Paolo Jay B Albarico,Yee Cheng Lim,Yun-Ru Ju,Jia-Wei Cheng,Cheng-Di Dong

doi:10.3390/w14030287

Abstract

A naval ship’s exhaust gas scrubber may discharge polycyclic aromatic hydrocarbons (PAHs) into seawater. Due to the high lipophilicity and low water solubility of PAHs, their concentrations in seawater are extremely low, making them difficult to detect or accurately determine. To accurately assess the impact of scrubber washwater effluent on the PAHs concentration of seawater, appropriate analysis methods must be established. In this study, a large-volume pre-concentration water sampler was used onboard to concentrate PAHs in surface seawater (100 L) from four sites offshore of southern Taiwan. The quantitative and qualitative analysis of dissolved PAHs in seawater and quality control samples were implemented using a GC/MS system with the aid of internal and surrogate standards. Results showed that the field and equipment blank samples of quality control samples were lower than twice the detection limit. The detection limit of individual PAHs is between 0.001 (naphthalene, NA) and 0.014 ng/L (dibenzo[a,h]anthracene, DBA), which meets the requirements for evaluating PAHs in seawater (that is, less than the maximum permissible concentrations (MPCs)). The concentration of total PAHs (TPAHs) in the four seawater samples ranged from 2.297 to 4.001 ng/L and had an average concentration of 3.056 ± 0.727 ng/L. The concentrations of 16 PAHs were determined in each seawater sample, indicating that the analytical method in this study is suitable for the determination of low-concentration PAHs in seawater. Phenanthrene (PHE) is the most dominant compound in seawater samples accounting for 59.6 ± 12.6% of TPAHs, followed by fluorine (FL) accounting for 8.5 ± 3.7%. The contribution of high-ring PAHs to TPAHs is not high (0.5–9.2%), but the observed concentrations can cause a higher risk to aquatic organisms than low-ring PAHs. The diagnostic ratio showed that the sources of PAHs in the seawater collected offshore of southern Taiwan may include mixed sources such as petrogenic, petroleum combustion, and biomass combustion. The results can be used for regular monitoring, which contributes to pollution prevention and management of the marine environment.

Highlights

Polycyclic aromatic hydrocarbons (PAHs) are a kind of persistent organic pollutants which are ubiquitous in the marine environment
There were no significant differences in temperature and salinity between the four areas, indicating that the hydrological conditions are similar
This study developed an on-site large-volume pre-concentration method for the determination of low-concentration polycyclic aromatic hydrocarbons (PAHs) in seawater

Summary

Introduction

Polycyclic aromatic hydrocarbons (PAHs) are a kind of persistent organic pollutants which are ubiquitous in the marine environment. They are toxic, mutagenic, carcinogenic, and bioaccumulative [1,2]. The high lipophilicity and low water solubility of PAHs make them easy to adsorb on organic matter and/or accumulate in the biota after entering the water environment [7]. Most PAHs may be deposited on the seafloor and stored in sediments, some still exist in the seawater column. PAHs in a seawater column can be directly accumulated in marine organisms through the gills or skin and cause potential hazards. Understanding the concentration of dissolved PAHs in seawater and their potential ecological risks are crucial for marine ecosystems research due to their potential harm even at lower concentrations [7,10]

Methods

Results

Conclusion