Rosa M. Vilanova

Persistent organic pollutants in snow from European high mountain areas

Snow cores were collected in the catchment area of five remote mountain lakes in Europe. They were analysed for polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), and organochlorine pesticides, namely DDTs, hexachlorobenzene (HCB) and hexachlorocyclohexanes (HCH). PAH are found in higher amounts in the Tatra and Caledonian mountains, PCB are higher in the Alps and HCH are highest in the Alps and Pyrenees. The qualitative PAH distributions are dominated by low molecular weight compounds, phenanthrene being the most abundant PAH in all but in one site. These compounds also occur predominantly in the gas phase in the atmosphere. Their high abundance in the snowpack witness the occurrence of effective transfer mechanisms from gas to snow flakes. In Starolesnianske (Tatra mountains), a higher contribution of high molecular weight compounds is found. This site exhibits the highest snow PAH and suspended particulate levels. Transformation of the concentration values of these compounds into annual deposition rates and correction for catchment/lake area indicates that in Scandinavia and the Alps a large proportion of PAH incorporation is mediated by snowfallout whereas in the Tatra mountains snow deposition only accounts for a small fraction of the compounds stored in the lake sediments. Among organochlorine compounds, only PCB and HCH have been found above method detection limit in most of the samples. The PCB congener distributions changes significantly between sites, although a predominance of the less chlorinated congeners have generally been observed.

POLYCYCLIC AROMATIC HYDROCARBONS IN REMOTE MOUNTAIN LAKE WATERS

Polycyclic aromatic hydrocarbons (PAH), including alkylated and sulfur derivatives, were identified and measured in the waters from three European remote mountain lakes during both ice-free and ice covered periods. The measured concentrations were in the same order in all three lakes (700-1100 pg/l). The PAH patterns in both dissolved and particulate water phases were dominated by the low molecular weight compounds (i.e. phenanthrene, fluoranthene and pyrene) in Lakes Redó (Pyrenees) and Gossenkölle (Alps). In contrast, the high molecular weight (HMW) compounds (i.e. chrysene+triphenylene, benzofluoranthenes, benzo[e]pyrene) were very significant in lake Ovre Neådalsvatn (Caledonian). These HMW PAH correspond to mixtures originating from high temperature combustion processes which have been photodegraded during long range atmospheric transport and parallel the PAH mixtures encountered in the underlying lake sediments. In contrast, dissolved PAH exhibit temperature dependence with higher concentrations found at water temperatures below 6-7 degrees C reflecting higher condensation from the atmospheric gas phase reservoir.

Analysis of trace polycyclic aromatic hydrocarbons and organochlorine compounds in atmospheric residues by solid-phase disk extraction

Abstract A method based on the use of solid-phase extraction disks for the analysis of polycyclic aromatic hydrocarbons and organochlorine compounds (pg l−1) in deposition samples collected in remote sites is described. Diverse aspects determining extraction efficiencies such as packing composition (C8 and C18), extraction number and elution solvents have been evaluated. The lowest relative standard deviations (3–20%) and best extraction efficiencies (80–100%) have been obtained using a solvent program of methanol, cyclohexane and dichloromethane (5 ml each) and octadecylsilane disks. Detection and quantitation limits were in the order of 0.14–3.5 pg l−1. These limits were achieved by gas chromatography coupled to mass spectrometry and detection in the selected ion monitoring mode.

Enhanced sensitivity in the analysis of trace organochlorine compounds by negative-ion mass spectrometry with ammonia as reagent gas

A comparison of the performances of ammonia and methane as reagent gases for the analysis of trace organochlorine compounds by gas chromatography coupled to negative-ion chemical ionization mass spectrometry is performed in the present study. Examples of standard mixtures and human blood samples analyzed with both reagents in scan and selected-ion monitoring mode are shown. Important advantages are observed as a consequence of the use of ammonia. These concern detection and quantitation limits and the lower dependence of sensitivity on the degree of chlorine substitution of the compounds.

Polychlorinated biphenyl partitioning in the waters of a remote mountain lake.

The dissolved-particulate phase distribution of polychlorobiphenyls (PCBs) in the waters of a high mountain lake (Redó Lake, Pyrenees) has been studied. The lake is oligotrophic and its water hydrology is dominated by atmospheric precipitation; inputs from catchment or other sources are not significant. Samples were collected in several periods encompassing the summer and winter seasons. The PCB congener concentrations were rather uniform both in terms of water depth and seasonality showing steady state conditions. Seventy percent of the variation of the PCB particulate-dissolved phase coefficient (Kd) was correlated with temperature and log octanol-water (Kow)). Lower temperatures and hydrophobicity involved a higher association with the particulate phase. This behavior is consistent with the predominance of plankton among suspended particles following a two compartment model. Thus, temperature dependence seems mainly related to a rapid phase transfer mechanism such as surface adsorption to the cell membranes and log Kow influence could reflect steric restrictions for the uptake of these compounds upon algal ingestion.

Remote mountain lakes as indicators of diffuse acidic and organic pollution in the Iberian peninsula (AL:PE 2 studies)

In the framework of the AL:PE 2 project, studies on acidification and organic pollution in mountain lakes have been conducted in several ranges in the Iberian peninsula: Pyrenees (Northeastern Spain), Sierra de Gredos (Central Spain), Sierra Nevada (Southern Spain) and Serra da Estrela (Central Portugal). These studies focused on water and sediment chemistry and organisms (benthic diatoms, Zooplankton, aquatic macroinvertebrates, and fish) as indicators of acidification. Organic micropollutants (PAH, PCB, DDE, hexachlorobenzene and others) in lake sediments and fish have been studied as tracers of atmospheric pollution. The Iberian peninsula lakes do not show severe anthropogenic acidification. pH values are in the range of sensitive lakes, but the levels of acidic pollutants are low. The status of the organisms surveyed agreed with this diagnosis. Pyrenean lakes showed the highest fluxes of organic pollutants related to fossil fuel combustion., higher pollutioninduced versus natural acidity ratios, and modeled alkalinity and pH declines.

PAH Distributions in Sediments from High Mountain Lakes

Abstract The PAH distributions in sediment cores from eight remote lakes distributed over Europe have been investigated. All sites show a similar qualitative composition, being dominated by parent compounds from phenanthrene to coronene. Perylene, a diagenetically produced PAH, dominates the mixtures in deep sediment layers. The distribution and ratios of specific compounds indicate that these hydrocarbons are of pyrolitic origin, mainly from coal combustion processes, but contributions from other sources are also present (i.e., retene is probably indicative of wood combustion inputs). The qualitative differences due to inputs, sources or physico-chemical conditions are discussed.

Spatial and Temporal Comparison of Polycyclic Aromatic Hydrocarbons and Spheroidal Carbonaceous Particles in Remote European Lakes

Spheroidal carbonaceous particles (SCP) and polycyclicaromatic hydrocarbons (PAH) have been measured in the dated sediment cores of 10 remote lakes distributed across Europe. The geographic trends were evaluated by examination of the superficial sediment fluxes and total sediment inventories. The highest levels of both markers were observed in the Eastern European lakes whereas the minimal values corresponded to the lake located in the Arctic. However, this SCP-PAH correlation was not observed after exclusion of the end member lakes from the series. The temporal trends of both pollutant markers are consistent with the history of pyrolytic emissions over Europe. However, the downcore SCP distributions are shorter than the PAH profiles in nearly all lakes. The differences are probably related to the different size particle fractions involved in the measurement of each marker, >5 and >1 μm for SCP and PAH, respectively. Thus, the two proxies probably reflect pollution inputs from closer (SCP) and more distant sites (PAH).

Retention time repeatability as a function of the injection automatism in the analysis of trace organochlorinated compounds with high-resolution gas chromatography

Abstract Short-term precision in retention time determination of different injection systems (three manual and three autosamplers) is assessed in the present study. This evaluation has been performed on eight different instrumental set-ups equipped with the same type of capillary column (30 m, 5% phenyl-95% methyl) which have been used for the analysis of standard mixtures of α,, γ-, and δ-hexachlorocyclohexanes. The results show that, as expected, retention time repeatability increases with the degree of automatization of the injection system. They also show that only the autosamplers and the manual injector provided with the syringe-operated start device are suitable for analysis of compounds with retention time differences in the order of 0.1 min. Conversely, none of the systems included in the study, not even the autosamplers, is adequate for the analysis of analytes having retention time differences of about 0.01 min.

Selectivity effects m semi-polar columns. II

Abstract Significant selectivity differences between semi-polar capillary gas chromatographic columns involving the elution order of acyclic and polycyclic lipid molecules have been observed. These differences occur despite these columns being reported to be “equivalent” in catalogue specifications. In Part I, the changes in retention indices between columns manufactured by different companies were described. In this paper, it is shown that these variations in selectivity may even be observed among semi-polar columns originating from the same manufacturer.