Source Identification and Sedimentary Record of Polycyclic Aromatic Hydrocarbons in Lake Bled (NW Slovenia) Using Stable Carbon Isotopes
ABSTRACT A combination of molecular and stable isotope analyses was used to trace and identify the sources of polycyclic aromatic hydrocarbons (PAH) in sediments of Lake Bled (NW Slovenia). Sediment samples were taken from two locations with contrasting depositional regimes: Zaka Bay, with permanently oxic bottom and station D, where anoxic conditions prevail throughout the year. The concentrations of PAH in surface sediments at the two locations were comparable and higher than in previous studies, reaching 4,230 and 4,380 ng g 1, respectively. It was found that Reten (Re) and Perylene (Per) are both mainly of natural origin in Zaka Bay while, at station D, the value of 13C determined at a depth of 12-14 cm in the 1950s indicated that Re was of pyrolytic origin. The distribution of 13C values of other individual PAH showed that PAH input to lake sediments was of pyrolytic origin, likely dominated by coal and later in 1950s also by wood burning. PAH from vehicular emissions could also contribute to the overall isotope signatures at the depth of 12-14 cm at station D and Zaka Bay corresponding to the period 1953-1961.
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ABSTRACT: Metals are ubiquitous in the environment. The aim of sustainable management of the agro-ecosystem includes ensuring that water continues to fulfill its function in agricultural production, cycling of elements, and as a habitat of numerous organisms. There is no doubt that the influence of large-scale irrigation projects has impacted the regional surface-groundwater interactions in the North China Plain (NCP). Given these concerns, the aim of this study is to evaluate the pollution, identify the sources of trace metals, analyze the influence of surface-groundwater interactions on trace metal distribution, and to propose urgent management strategies for trace metals in the agriculture area in China. Trace metals, hydrochemical indicators (EC, pH, concentrations of Na(+), K(+), Mg(2+), Ca(2+), Cl(-), SO4(2-), and HCO3(-)) and stable isotopic composition (δ(18)O and δ(2)H) were determined for surface water (SW) and groundwater (GW) samples. Trace metals were detected in all samples. Concentrations of Fe, Se, B, Mn, and Zn in SW exceeded drinking water standards by 14.8%, 29.6%, 25.9%, 11.1%, and 14.8% higher, respectively, and by 3.8%, 23.1%, 11.5%, 11.5%, and 7.7% in GW. The pollution of trace metals in surface water was more serious than that in groundwater, and was also higher than in common irrigation areas in NCP. Trace metals were found to have a combined origin of geogenic and agriculture and industrial activities. Their distribution varied greatly and exhibited a certain relationship with the water flow direction, with the exception of a number of singular sites. Hydrochemical and environmental isotopic evidence indicates surface-groundwater interactions influence the spatial distribution of trace metal in the study area. Facing the ongoing serious pollution, management practices for source control, improved control technologies, and the construction of a monitoring net to warn of increased risk are urgently needed.Science of The Total Environment 12/2013; 472C:979-988. DOI:10.1016/j.scitotenv.2013.11.120 · 3.16 Impact Factor
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ABSTRACT: Analyses of sediment core samples are primary sources of historical pollution trends in aquatic systems. Determining organic compounds, such as POPs, in the dated sediments enables the estimation of their temporal concentration changes and the identification of the contaminant origin in local regions. Wars, large-scale fires, economical transitions, and bans on certain chemicals are reflected in the sediment organic compound concentrations. The high POP concentrations in surficial sediments suggest that these chemicals, even after being banned, remain in the environment. Furthermore, vertical profiles can help in understanding the sedimentation process and in estimating effective countermeasures against pollution. Moreover, studies published during the period 1991-2013 on PAHs, PCBs, OCPs, dioxins and dioxin-like compound concentrations in sediment core samples are reviewed.Marine Pollution Bulletin 11/2013; 78(1-2). DOI:10.1016/j.marpolbul.2013.11.008 · 2.79 Impact Factor
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ABSTRACT: Elemental carbon (EC) and polycyclic aromatic compounds (PACs) are potential proxies for the reconstruction of change in human activities and the origin of air masses in historic times. In this study, the historic deposition of char and soot (the two subtypes of EC) and PACs in a 150-yr sediment core from different topographic sub-basins of Lake Qinghai on the Qinghai Tibetan Plateau (QTP) were reconstructed. The objective was to explore how the variations in the concentrations of EC and PACs, the ratios of char to soot and of oxygenated-PAHs to parent-PAHs and of the composition of the PACs mixtures reflect historical changes in climate and human activity and the origin of air masses arriving at QTP. The deposition fluxes of soot in the different sub-basins were similar, averaging 0.18 (range of 0.15-0.25) and 0.16 (0.13-0.23) g m-2 yr-1, respectively, but varied for char (averaging 0.11 and 0.22 g m-2 yr-1, respectively), suggesting ubiquitous atmospheric deposition of soot and local river inputs of char. The different vertical distributions of the char/soot ratios in the different sub-basins can be interpreted by the different transport mechanisms of char and soot. An abrupt increase in soot concentrations since 1980 coincides with results from the QTP ice cores that were interpreted to be indicative of soot transport from South Asia. Similar concentration pattern of PAHs with soot and the 9,10-anthraquinone/anthracene (9,10-AQ/ANT) ratios all >2.0 suggest regional PAC sources. Increasing PAHs/soot ratios and decreasing 9,10-AQ/ANT ratios since the beginning of the 1970s indicate increasing local emissions. The historical trends of diagnostic ratios indicate an increase in fossil fuel contribution since the beginning of the 1970s. The increase of perylene concentrations with increasing core depth and the ratio of perylene to its penta-aromatic isomers indicate that perylene originates mainly from in-situ biogenic diagenesis. We demonstrate that the concentrations of EC, char, soot, and PACs in sediments can be used to reconstruct local, regional, and remote sources and transport pathways of pollutants to the QTP.Environmental Science and Technology 03/2015; 49(7). DOI:10.1021/es504568m · 5.48 Impact Factor