An assessment of the concentrations of PCDDs/Fs in contaminated bottom sediments and their sources and ecological risk

Agnieszka Baran,Monika Mierzwa-Hersztek,Marek Tarnawski,Krzysztof Gondek,Magdalena Urbaniak,Marek Zieliński,Magdalena Szara

doi:10.1007/s11368-019-02492-3

Abstract

PurposeThe purpose of the study was to determine the levels of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F), two types of persistent organic pollutant (POP), in an urban retention reservoir located in an industrial zone within a coal-mining region. It also assesses the potential ecological risk of the PCDDs/Fs present in bottom sediments and the relationship between their content and the fraction of organic matter.Materials and methodsThe sediment samples were collected from Rybnik Reservoir, located in the centre of the Rybnik Coal Region, Silesia, one of Poland’s major industrial centres. Seventeen PCDD/F congeners in the surface of the sediments were analysed using high-resolution gas chromatography and high-resolution mass spectrometry (HRGC/HRMS).Results and discussionThe toxic equivalency (TEQ) of the PCDDs/Fs in the sediments ranged from 1.65 to 32.68 pg TEQ g−1. PCDDs constituted 59–78% of the total PCDDs/Fs, while the PCDFs accounted for 22–41%. The pattern of PCDD/F congeners in the sediments was dominated by OCDD. However, the second-most prevalent constituents were OCDF and ∑HpCDFs in the low TOC sediment (< 10 g TOC kg−1), but HpCDD in the rich TOC samples (> 10 g TOC kg−1). PCDD/F concentrations in the sediment samples were 2- to 38-fold higher than the sediment quality guidelines limit, indicating high ecological risk potential. Although a considerable proportion of PCDDs/Fs in the bottom sediments from the Rybnik Reservoir were derived from combustion processes, they were also obtained via transport, wastewater discharge, high-temperature processes and thermal electricity generation. The PCDD/F concentrations were significantly correlated with all fractions of organic matter; however, the strongest correlation coefficients were found between PCDDs/Fs and humic substances. Besides organic matter, the proportions of silt/clay fractions within sediments played an important role in the transport of PCDDs/Fs in bottom sediments.ConclusionsThe silt/clay fraction of the bottom sediments plays a dominant role in the movement of PCDDs/Fs, while the organic matter fraction affects their sorption. The results indicate that the environmental behaviour of PCDDs/Fs is affected by the quantity and quality of organic matter and the texture of sediments.

Highlights

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs) are both examples of persistent organic pollutants (POPs) (Lee et al 2006; Li et al 2012; Lewandowski et al 2014; Förstner et al 2016; Louchouarn et al 2018)
The distribution of PCDDs/Fs in the sediments was characterised by a high share of OCDD and > HpCDD > OCDF (TOC > 10 g kg−1 d.m) and > ∑HpCDFs > OCDF (TOC < 10 g kg−1 d.m.). 2
The congener profile of PCDDs/Fs in the bottom sediments indicated that they were primarily derived by emission from the combustion processes

Summary

Introduction

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs) are both examples of persistent organic pollutants (POPs) (Lee et al 2006; Li et al 2012; Lewandowski et al 2014; Förstner et al 2016; Louchouarn et al 2018). PCDDs/Fs demonstrate good stability in a water environment; this has been attributed to their low solubility and strong adsorption on organic matter particles and lipids, which results in up to 97% of emitted PCDDs/Fs being deposited in sediments Due to their high octanol-water partition confections (log Kow 4–8), PCDDs/Fs undergo bioaccumulation in sediment-dwelling organisms and biomagnification in both aquatic and terrestrial food chains (Lee et al 2006; Micheletti et al 2007; Nunes et al 2011; Nie et al 2013; Urbaniak et al 2014; Förstner et al 2016; Roumak et al 2018). The precise qualitative and quantitative composition of organic matter, including humus substances, soluble organic matter and black carbon fractions, is believed to be a key element in determining potential PCDD/F accumulation in bottom sediments (Perminova et al 2006, 2019; Ghosh 2007)

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