Historical changes in the concentrations of polycyclic aromatic hydrocarbons (PAHs) in Lake Peipsi sediments

Abstract

The distribution of 11 individual polycyclic aromatic hydrocarbons (PAHs) was analysed in a (210)Pb dated sediment core from the deepest area of Lake Peipsi and in four surface sediment samples taken from littoral areas. According to the concentrations in the core three groups of PAHs may be distinguished: (1) relatively stable concentrations of PAHs within the whole studied time interval; (2) very low concentrations in sediments accumulated before intensive anthropogenic impact (from 19th century up to the 1920s) following a slight increase and (3) an overall increase in PAH concentrations since the 1920s up to the present. Comprehensive analysis of PAHs in the core and monitoring data obtained in the 1980s together with the lithology of sediments show that an increase of anthropogenically induced PAHs correlates well with the history of fuel consumption in Estonia and speaks about atmospheric long-distance transport of PAHs. The continuous increase of PAH concentrations since the 1920s do not support the earlier hypothesis about the dominating impact of the oil shale fired power plants near the lake, because their emissions decreased significantly in the 1990s. The concentration of PAHs in the deep lake core sample correlates well with the content of organic matter, indicating absorption and co-precipitation with plankton in the sediment.

Historical changes in polycyclic aromatic hydrocarbons (PAHs) input in Lake Baiyangdian related to regional socio-economic development

“…The second peak occurred between 1985 and 1995, fast industrialization and urbanization in this period in the catchment might cause much more PAH emission [28]. These results suggest that the periods of warfare and recent accelerated economic activities had strong impacts on the vertical distribution of PAHs [29,30]. The variation in the total PAH concentration over time is basically consistent with the historical economic and social development of this catchment for China.…”

Environmental hazard of oil shale combustion fly ash

“…As the studied area shows high variability in composition of the parent material, the role of natural sources of trace elements might be significant. Analogously, Punning et al [59] have shown that the role of emissions from oil-shale combustion in environmental contamination by previous investigations has been overestimated.…”

Pool of mobile and immobile phosphorus in sediments of the large, shallow Lake Peipsi over the last 100 years

“…The effect of sediment mixing is also seen from the distribution of fly-ash particles in sediments in the core taken nearby (Nõges et al 2006). Sediment resuspension is also evidenced by the great variations of diatom communities in the surface sediments over relatively short distances (Davydova 1981;Punning et al 2008). Resedimentation, including the mixing of sediment by organisms or other processes, could disrupt the smooth profile and reduce the accuracy of the estimated dates and sediment accumulation rates (Punning et al 2008.…”

“…Due to aerobic and anaerobic redox processes, not only organic C compounds but also organic P compounds are turned over (Turner et al 2005;Kleeberg et al 2010). The low C/N ratios (<9) indicate that the NaOH extractable organic P compound groups included in the precipitate originate from autochthonous matter (Punning et al 2008). Most of the NaOH-P extract was in dissolved (<0.4 μm) form (for silt sediments core PS509 average 114.85 μg g -1 DW, and for sand/ peat sediments core PS2009 average 253.4 μg g -1 DW), could be generally described as organic P, especially as P bound on humic substances (Uhlmann et al 1990), as P accumulated in microorganisms (Waara et al 1993) or as special organic compounds such as phospholipids (Baldwin 1996), suggesting that the LMW OM was rich in P. The positive loading observed in PC1 reveals that OM regulates the vertical distribution of NaOH-LMW-NRP in silt sediments.…”