Atmospheric deposition of PAHs to an urban site, Paris, France

International audienc

A Single Law to Describe Atmospheric Nitrogen Bulk Deposition versus Rainfall Amount: Inputs at the Seine River Watershed Scale

International audienceAtmospheric nitrogen species (NH 4-N and (NO 3 +NO 2)-N) were determined in weekly samples of atmospheric bulk deposition (dry plus wet), collected in France at seven sites over the course of a year. Rural, semi-rural and industrialised-urban sites were chosen in the Seine river watershed from the Seine estuary to upstream from Paris. Mean NH 4-N concentrations varied from 0.7 to 1.7 mg L −1. Mean (NO 3 +NO 2)-N concentrations were approximately 0.5 mg L −1 for all sites except Paris (0.7 mg L −1), which has a local impact on the fallout contamination from urban emissions. The relation between concentration and rainfall amount obeys a power law, in the form of y = ax b. When the nitrogen sources are very local, this relationship turns into a dilution law. Annual atmospheric nitrogen deposition (NH 4-N+(NO 3 +NO 2)-N) was calculated and varied from 7.8 kg ha −1 yr −1 in the neighbourhood of a rural town to 17.3 kg ha −1 yr −1 in a very industrialised harbour. 58% of the atmospheric nitrogen deposition occurred during 'spring + summer' period. The total nitrogen atmospheric input to the Seine estuary, via direct deposition + indirect input via the watershed, was estimated to about 5% of the total nitrogen load within the Seine river basin

Atmospheric bulk deposition of trace metals to the Seine river basin : concentrations, sources and evolution during 1988-2001.

Concentrations of Cd, Cu, Ni, Pb and Zn were determined in bulk atmospheric deposition collected at five stations in the Seine River basin (France), to evaluate sources and fluxes of atmospheric trace metals. Bulk deposition (wet + dry) was sampled weekly from March 2001 to February 2002 for 4 sites and from March to December 2001 for the last one. The concentrations of the elements in bulk deposition (dissolved + particulate form) followed the order: Zn > Pb > Cu > Ni > Cd. Concentrations of Zn, Pb and Ni were highly correlated with one another, suggesting a common source, related to the combustion of coal and heavy fuel. Metal concentrations in bulk deposition did not exhibit a high degree of temporal variability over the annual cycle and were not obviously related to meteorological parameters (rainfall, wind). Estimates of the total annual direct atmospheric deposition of metals to the Seine Estuary ranged from 16 kg yr− 1 for Cd to 5600 kg yr− 1 for Zn. Loadings of Cd, Cu and Ni from direct atmospheric inputs were less than 1% of those contributed by the Seine River and loadings of Pb and Zn represented 1.27% and 1.56% of the Seine contribution. Direct atmospheric inputs are negligible compared to fluvial inputs, but the indirect atmospheric deposition to the estuary was not estimated. Based on these results, trace metal concentrations in Paris have decreased by a factor of 4.6 for Zn and by a factor of 50 for Ni from 1988 to 2001. Of particular interest is the continued decrease in bulk deposition of Pb during this period, underlining the impact of policy initiatives concerning the reduction of lead on emissions in France

Atmospheric deposition of toxics onto the Seine Estuary, France: example of polycyclic aromatic hydrocarbons

International audienceConcentrations of Polycyclic Aromatic Hydrocarbons (PAH) were measured in precipitation samples on a weekly basis between March and October 2001, at four sites in the Seine Estuary (France). Mean concentrations of total PAHs (S 14 PAHs) ranged from 38 to 141 ng L-1. Fluoranthene, phenanthrene and pyrene were the dominant PAH compounds and were detected in each sample. The six potential carcinogenic PAHs accounted for 20 to 25% of the total PAH concentration in bulk deposition. The PAH signatures in bulk (wet and dry) deposition and surface water were also compared to investigate source/sink relationships. Seasonal patterns were observed with maximum loading occurring during the colder months of the studied period (March and April). Mean values of daily flux reported for S 14 PAHs ranged from 108 to 267 ng m-2 d-1. Spatial influences were also observed, indicating both localized and long-range atmospheric source inputs (controlled by hydroclimatic parameters)

A wavelet approach to the short-term to pluri-decennal variability of streamflow in the Mississippi river basin from 1934 to 1998

International audienceThe temporal variability of streamflow in the Mississippi river basin, including its major tributaries (Missouri, Upper Mississippi, Ohio and Arkansas rivers), was analysed using continuous wavelet methods in order to detect possible changes over the past 60 years. Long- to short-term fluctuations were investigated. The results were compared with SOI, PDO and NAO indices and precipitation time series and were also processed by wavelet methods. A major change point around 1970, also reported in other works, was recovered in all climate and hydrological processes. It is characterised by the occurrence of an 8-16-year mode for Upper Mississippi and Missouri and of a 3-6-year mode for all rivers. Two other discontinuities around the mid-1950s and 1985 were also detected. A strong power attenuation of the annual cycle in the Arkansas, Upper Mississippi and Missouri rivers was also found between 1955 and 1975. In general, the dominant modes of inter-annual to pluri-annual streamflow variability lay in the 2-4-year, 4-8-year and 10-16-year ranges, which was typical of SOI for the period of study. A preferential link with the Mississippi basin headwater zone (i.e. Upper Mississippi and Missouri) was deduced during the 1934-1950 and 1970-1985 periods. Overall, the contribution of inter-annual to pluri-annual oscillations ranged from 6.6 to 26% of streamflow variance, while the short-term scales (<2-3 weeks) explained from 1.1 to 6.4%. The annual cyclicity explained from 19.1 to 48.6% of streamflow variance. High-frequency streamflow fluctuations linked to synoptic activity were also found to increase after 1955 for all basins except Upper and Lower Mississippi, apparently modulated by a 2-4-yr oscillation. Copyright © 2009 Royal Meteorological Societ

Atmospheric bulk deposition of PAHs onto France: trends from urban to remote sites

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Mass balance for polycyclic aromatic hydrocarbons in the urban watershed of Le Havre (France): Transport and fate of PAHs from the atmosphere to the outlet

International audiencePolycyclic aromatic hydrocarbon (PAH) concentrations have been monitored simultaneously in ambient air, bulk atmospheric deposition and runoff waters during one year in a small urban watershed of the Seine river basin (France). PAH fluxes from the atmosphere to the outlet of the urban watershed have been calculated to establish a mass balance for PAHs. PAH flux in runoff waters was 5.2 kgkm-2 yr-1 while PAH atmospheric deposition was 0.21 kgkm-2 yr-1. The comparison between atmospheric input and output by runoff has shown the importance of street deposits that appeared to be the most important source of PAHs for surface waters in urban areas. PAH profiles in the various compartments showed the fate of PAHs in the air–water system: proportion of carcinogenic PAHs was more important in runoff waters (35%) than in bulk atmospheric deposition (22%) and air (6%)

Fluxes of polycyclic aromatic hydrocarbons in the Seine estuary, France : mass balance and role of atmospheric deposition

Measurments of polycyclic aromatic hydrocarbons (PAHs) were carried out from 2001 to 2003 in various environmental compartments (ambient air, atmospheric deposition, soils, sediments, runoff, and surface waters) in the Seine estuary. The goal of this study was to identify the importance of atmospheric fluxes to occurence of PAHs in the estuary, and to estimate the major pathways of their transport and accumulation within this ecosystem. The annual atmospheric inputs in the estuary ranged from 2.5 to 16kg for the first sampling year, which is high when compared to those calculated for other European locations. In parallel, PAH transport from the atmosphere to the watershed outlet was investigated for two rural and urban small experimental watersheds within the Seine Estuary. In rural areas, atmospheric inputs are higher than exported loads by surface water and PAHs are accumulating in soils. The inverse occurs in urban areas, where the contribution of atmospheric deposition is negligible ompared with PAH exported loads by runoff. These results allowed us to establish a mass balance for PAHs on the scale of the Seine Estuary, and to determine the dynamics of PAH transport. This study highlights the role of the atmospheric compartment in the transfer of contaminants and the importance of the local PAH inputs within the Seine Estuary