Geochemical Control of PAHs by Inflowing River Water to West Nanao Bay, Japan, and Its Influences on Ecological Risk: Small-Scale Changes Observed under Near-Background Conditions at an Enclosed Bay.

Rodrigo Mundo,Hisanori Iwai,Shinya Ochiai,Seiya Nagao,Tetsuya Matsunaka

doi:10.3390/ijerph181910310

Abstract

Polycyclic aromatic hydrocarbons (PAHs), even at low concentrations, have been shown to trigger changes in life cycles and provoke abnormal behaviors in numerous marine organisms. From May 2019 to September 2020, particulate and dissolved PAH concentrations were analyzed on the surface water of West Nanao Bay, Japan, to determinate their levels, emission sources, environmental pathways, and ecological risks at this remote but semi-enclosed bay. The 14 targeted PAHs were analyzed by HPLC-fluorescence detector. Mean total PAH concentrations were lower than 20.0 ng L−1 for most samples. Based on fluoranthene (Flu) to pyrene (Pyr) ([Flu]/[Flu + Pyr]) and benzo[a]anthracene (BaA) to chrysene (Chr) ([BaA]/[BaA + Chr]) isomeric ratios and a varimax rotated PCA, it was established that biomass combustion was the principal source in the particulate phase and that liquid fossil fuel combustion was the principal source in the dissolved phase. From salinity and turbidity distribution, riverine discharges were determined to be the major and continuous transportation pathway of particulate PAHs. It was observed that rain events had a role in the transport of dissolved PAHs. The risk quotients (RQ∑14 PAHs (NCs): 0–84.53) indicated that PAHs represented a very low to low acute environmental risk. The results of this study will contribute to filling the paradigm gap of ecotoxicological studies in remote areas, working as a booster for future in-lab studies of non-lethal implications of endocrine disruptors such as PAHs.

Highlights

Polycyclic aromatic hydrocarbons (PAHs), released to the environment mainly from the incomplete combustion of fossil fuels and biomass as well as from the leakage of petroleum derivates [1,2], are hazardous pollutants with adverse carcinogenic and/or mutagenic potential [3]
From May 2019 to September 2020, particulate and dissolved PAH average concentrations were repeatedly analyzed in a four-seasons-long monitoring survey performed on surface waters of West Nanao Bay, Japan
Mean total PAH concentrations were lower than 20.0 ng L−1 for most samples

Summary

Introduction

Polycyclic aromatic hydrocarbons (PAHs), released to the environment mainly from the incomplete combustion of fossil fuels and biomass as well as from the leakage of petroleum derivates [1,2], are hazardous pollutants with adverse carcinogenic and/or mutagenic potential [3]. PAHs, even at low concentrations, have been shown to trigger changes in life cycles and to provoke abnormal behaviors in numerous marine organisms [4,5,6,7,8]. As mainly a hormone-regulated process, fish reproduction is very sensitive to physical and chemical stressors, such as PAHs [9]. Nicolas (1999) summarized the direct effects of PAHs in increasing vitellogenesis in various species of fish [4]. Vitellogenesis in most species of fish occurs only once in the reproductive cycle. Even in non-lethal concentrations, PAHs have the potential to affect the whole reproductive cycle of the organism, leading to a gradual decrease in the population [4,11,12,13,14].

Objectives

Methods

Results

Conclusion