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

Abstract

Purpose The 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 methods The 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 discussion The 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. Conclusions The 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.

Concentration of dioxin and screening level ecotoxicity of pore water from bottom sediments in relation to organic carbon contents

“…Besides organic matter, the clay and silt fractions of sediments play an important role in the distribution of dioxins in bottom sediments (Zhang et al 2010;Li et al 2012). In our previous study, fine fractions of sediments were demonstrated to play a dominant role in the distribution of dioxins in Rybnik Reservoir (Baran et al 2019c). Vácha et al (2011) and Lee et al (2006) also observed a poor relation between the concentration of organic pollutants and the content of TOC in the sediment.…”

“…It encloses a small catchment area, which is highly urbanised and strongly influenced by heavy industry (Baran et al 2019a ). In our previous studies, the concentration of PCDDs/Fs in the sediments form Rybnik reservoir ranged from 1.65 to 32.68 pg TEQ g −1 (Baran et al 2020 ). Morover, we found that PCDD/F concentrations in the sediments were 2–38-fold higher than the Sediment Quality Guidelines limit, indicating high ecological risk potential.…”

“…Morover, we found that PCDD/F concentrations in the sediments were 2–38-fold higher than the Sediment Quality Guidelines limit, indicating high ecological risk potential. The source of PCDDs/Fs in the bottom sediments from the Rybnik reservoir were from combustion processes, transport, wastewater discharge, high-temperature processes and thermal electricity generation (Baran et al 2020 ). Inflow of inorganic and organic pollution into the Roznów reservoir is high due to soil erosion, insufficient municipal wastewater treatment and village wastewaters (lack of sewage system in villages around the reservoir) and are emitted from fossil fuel (coal) combustion Morover, the silting process contributes to the inflow of fine fractions of both natural and anthropogenic origin is important source of pollutions in the bottom sediment (Baran et al 2019b ).…”

Impact of municipal and industrial waste incinerators on PCBs content in the environment

“…Humic substances are capable of ionic, donor-acceptor, and hydrophobic bonding. Therefore, they can bind POPs in non-toxic and nonbioavailable humic complexes [ 27 ]. The higher the soil pH, the lower the PCBs content is in the soil.…”

Sediment as a dynamic natural resource—from catchment to open sea

“…3 Sediment quality guidance, sediment quality assessment Baran et al (2019) present a study that assessed the levels of persistent organic contaminants such as polychlorinated dibenz-p-dioxin and polychlorinated dibenzofuran (PCDD/Fs) in lake sediments of the coal mining and highly industrial region in Poland. PCDD/F concentrations in the sediment samples were 2-to 38-fold higher than the sediment quality guidelines limits, indicating high ecological risk potential.…”