Polycyclic aromatic hydrocarbons in water and bottom sediments of a shallow, lowland dammed reservoir (on the example of the reservoir Blachownia, South Poland)

Abstract

The content of polycyclic aromatic hydrocarbons (PAHs) in water and sediments of the Blachownia reservoir (South Poland) was investigated. Spatial variability of PAH concentrations in the longitudinal profi le of the tank was determined. PAHs in samples were determined by gas chromatography coupled with mass spectrometric detection (GC-MS QP-2010 Plus Shimadzu) using an internal standard. Concentrations ranged from 0.103 μg/L to 2.667 μg/L (Σ16 PAHs) in water samples and from 2.329 mg/kg d.w. to 9.078 mg/kg d.w. (Σ16 PAHs) in sediment samples. A pollution balance was calculated and it was estimated that the infl ow load was 17.70 kg PAHs during the year and the outfl ow load was 9.30 kg PAHs per year. Accumulation of about 50% of the annual PAH loads (8.90 kg) is a threat to the ecological condition of the ecosystem. It was calculated that the PAH loads in bottom sediment were about 80 kg, which limits their economic use. Improvement of the ecological status of this type of reservoir can be achieved by removing the sediment. Analysis of the diagnostic ratios obtained for selected PAHs showed that the potential sources of PAH emissions in small agricultural – forest catchments can be combustion of a coal, wood, plant material (low emission, forest fi res, burning grass, etc.). Transportation is also signifi cant. Polycyclic aromatic hydrocarbons in water and bottom sediments of a shallow, lowland dammed reservoir... 11 in the environment or utilization (Kostecki 2003, Kostecki and Czaplicka 2001). Determining the relationship between selected PAHs can be used to defi ne the origin of the pollutant. Table 1 shows PAH diagnostic ratios with their typically reported values for particular processes. The aim of the study was to obtain knowledge about the role of lowland dam reservoir as the reactor in which the quality of water and bottom sediments is formed. The novelty scientifi c studies were to attempt to determine the relationship between the morphometry of the reservoir and PAHs concentration in sediments. In determining the spatial variability of concentrations in the longitudinal profi le of the reservoir, its depth diversity was taken into account. The aim of the study was to demonstrate the specifi city of the self-cleaning processes taking place in the lowland reservoirs. Using the balance method, the ecosystem’s ability to accumulate organic pollutants was determined. Research Methodology The object of studies The reservoir in Blachownia is an example of a typical lowland, dammed reservoir formed by damming the Stradomka river. Such reservoirs are important elements in local water management. By small differences in the level of damming they maintain the correct level of groundwater, thus reducing the effects of drought and fl oods during the spring and summer. They are valuable ecosystems enhancing biodiversity of fl ora and fauna. Additionally, they are a recreation area for local communities. The reservoir has an area of 47 hectares, and a capacity of about 500 000 m3. Its maximum depth in the area of the dam is about 2.0 m, and the average depth is about 1.0 m. The reservoir is fed by surface watercourses the Stradomka and the Trzepizurka. The total catchment area of the reservoir is equal to 113.33 km2, including the Stradomka catchment – 67.89 km2, and the Trzepizurka catchment – 22.11 km2 (Siwiński 2015). Population density in the municipalities bordering the reservoir fl uctuates between 80–113 people/km2. The land use in the area is dominated by woodland (47.2–62.0%) and agricultural lands (25.0–43.9%), while urbanized areas account for only 8.9–13.0% (CSO 2015). Before the analyzed reservoir, wastewater from mechanical-biological wastewater treatment plant (WWTP), from the village Herby, serving approximately 4,300 residents, and the capacity in 1100 m3/d, is fed to the Stradomka river. In addition, part of the village located in the catchment of the reservoir does not have a sewage system. Municipal wastewater management relies mainly on retention of sewage in cesspools, and its transport to the wastewater treatment plant (KZGW 2012). Sampling sites Water samples were collected at four points, fi ve times from May to September in 2013, at monthly intervals: W1 – the Stradomka river inlet stream, W2 – the Trzepizurka river inlet (the Aleksandrowski stream) to the reservoir, W3 – the reservoir, the place at the „lido”, W4 – the reservoir, outlet from the reservoir. Table 1. Diagnostic ratios used with their typically reported values for particular processes PAH ratio Value range Source Reference ∑LMW/∑HMW < 1 Pyrogenic Zhang et al. 2008 > 1 Petrogenic ∑COMB/∑PAHs ~ 1 Combustion Ravindra et al. 2008a FL/(FL + PYR) < 0.5 Petrol emissions Ravindra et al. 2008b > 0.5 Diesel emissions ANT/(ANT + PHE) < 0.1 Petrogenic Pies et al. 2008 > 0.1 Pyrogenic FLA/(FLA + PYR) < 0.4 Petrogenic De La Torre-Roche et al. 2009 0.4–0.5 Fossil fuel combustion > 0.5 Grass, wood, coal combustion BaA/(BaA + CHR) 0.2–0.35 Coal combustion Akyüz and Çabuk 2010 > 0.35 Vehicular emissions < 0.2 Petrogenic Yunker et al. 2002 > 0.35 Combustion IcdP/(IcdP + BghiP) < 0.2 Petrogenic Yunker et al. 2002 0.2–0.5 Petroleum combustion > 0.5 Grass, wood and coal combustion BbF/BkF 2.5–2.9 Aluminium smelter emissions BaP/BghiP < 0.6 Non-traffi c emissions Katsoyiannis et al. 2007 > 0.6 Traffi c emissions ΣLMW – sum of two and three-ring PAHs; ΣHMW – sum of four and fi ve ring PAHs; ΣCOMB – sum of FLA, PYR, BaA, CHR, BkF, BbF, BaP, IcdP and BghiP; ΣPAHs – sum of total 16 investigated PAHs; FL – Fluoren; PYR – Pyrene; ANT – Anthracene; PHE – Phenanthrene; FLA – Fluoranthene; BaA – Benzo(a)anthracene; CHR – Chrysene; IcdP – Indeno(1,2,3-cd)pyrene; BghiP – Benzo(g,h,i)perylene; BbF – Benzo(b)fl uoranthene; BkF – Benzo(k)fl uoranthene, BaP – Benzo(a)pyrene. 12 A. Pohl, M. Kostecki, I. Jureczko, M. Czaplicka, B. Łozowski Samples of bottom sediments (points S1–S5) were collected once with a Birge-Ekman bottom sampler at fi ve points along the central axis of the reservoir: S1 – the Stradomka river inlet zone, S2 – the reservoir island, S3 – the reservoir middle, S4 – the reservoir jetty, S5 – the reservoir dam, outlet from the reservoir (Fig. 1). Polycyclic aromatic hydrocarbons were measured in water and bottom sediment samples. Thickness of sediment layer, sediment humidity and organic matter were determined. In addition, water fl ow rates were measured (infl ow and outfl ow from the tank), which were the basis for calculating the pollution balance.