https://hal-enpc.archives-ouvertes.fr/hal-00676422/document

Historical perspective of heavy metals contamination (Cd, Cr, Cu, Hg, Pb, Zn) in the Seine River basin (France) following a DPSIR approach (1950-2005).

Anthropogenic components of heavy metal (Cd, Zn, Cu, Pb) budgets in the Lot-Garonne fluvial system (France)

We analyse average water and particulate chemistry (nutrients, major ions, heavy metals) in the Seine basin at 10 key positions, from stream order one to river mouth (order 8, 67000 km2), and for a population density gradient from one to 20 000 people km−2. Particulates are studied on stream deposited sediments and on recent riverflood deposits collected over two years. The impact of Paris megalopolis (10 M people for 2 300 km2) is considered both on the main river course and on periurban and urban streams. Average concentrations at each position are normalized for all variables to pristine levels, mostly determined on a set of forested headwaters, in order to define the ‘change ratio’. In the main river course these ratios vary from less than 0.5 for dissolved SiO2 to more than 10 for Na+, K+, particulate Hg and Zn, and exceeds 50 for NH4 +, PO4 −3 and NO2 −. They reach over two order of magnitude for NH4 + and PO4 −3 in urban streams now covered and used as sewers, the ultimate anthropogenic impact. Few variables, such as Mg++ and particulate Co, are not affected by human activities, and Ca+ and HCO3 − are regulated by calcite precipitation linked to river eutrophication. The change ratios can be used to describe the spatial structure of impacts. For each variable, the maximum impact position depends on the pollution mode and origin: NO3 − maximum is already noted in small agricultural streams but PO4 −3 maximum occurs at the most downstream stations. The maximum impact of the Paris megalopolis is observed more than 75 km downstream of the city centre (proximal impact) but the river water quality is still affected 200 km downstream (distal impact). In addition to this classical longitudinal impact mode, the megalopolis also creates radial impacts, and ‘inverse’ impacts due to flow regulations in upstream river reaches.

Man and river interface: multiple impacts on water and particulates chemistry illustrated in the Seine river basin

Routine measurements of river discharge and total suspended sediment concentration (TSS) are combined with regular analyses for particulate and dissolved cadmium to produce a box model that allows us to propose a cadmium mass balance for the Lot-Garonne man-influenced river system (8400 km2). Nearly half the cadmium in the Garonne river is supplied by the tributary Lot river. Cadmium input onto the Lot river comprises wet deposition from the atmosphere, molecular diffusion at the sediment-water interface, surface-water runoff and discharge from the leaching of waste at a zinc refining plant. Approximately 85% of the cadmium in the Lot river is derived from anthropogenic origin. Cadmium in the industrial discharge is 80% dissolved and 20% in the particulate phase (4.2 and 1.1 t yr−1, respectively). Total inputs are estimated at 4.81 t yr−1 and 1.54 t yr−1 for the dissolved cadmium and for the particulate phase, respectively. Budgeting estimates an output onto the Garonne river of 0.54 t yr−1 for the dissolved cadmium (about 8%) and 6.13 t yr−1 for the particulate cadmium (about 92%) indicating that downstream sediment-associated cadmium fluxes are enhanced by the 4.27 t yr−1 removed from solution and the 0.32 t yr−1 remobilized by the erosion of sediment blanketing the Lot river bed. These figures are found to be comparable with those generated by a dilution model which suggests that 97% of dissolved cadmium is taken up by the particulate phase over 0.5 km downstream from the primary anthropogenic source.

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A cadmium budget for the Lot-Garonne fluvial system (France)

Influence of the Gironde estuary outputs on cadmium concentrations in the waters: consequences on the Marennes-Oléron bay (France)

De janvier 1990 a mai 1992, la Seine a Poses (75 000 km2 , derniere station du Reseau National de Bassin avant l'estuaire) a fait l'objet d'une etude pilote tres complete (70 echantillons). Les contaminants inorganiques en traces (As, Cd, Cu, Hg, Pb, et Zn) presentes ici ont ete preleves et analyses dans des conditions ultrapropres ainsi qu'en attestent les concentrations en solution (ng/l) As = 990, Cd = 27, Hg = 3, Pb = 500, Cu = 1700, Zn = 9200. La pollution du fleuve est refletee par les teneurs moyennes dans les matieres en suspension (μ  g/g) : As = 8,5, Cd = 4,9, Hg = 1,2, Pb = 184, Cu = 174, Zn = 611. Les metaux Cd, Hg, Pb, Cu et Zn sont essentiellement sous forme particulaire. L'arsenic est preferentiellement sous forme dissoute sauf lors des crues (ou MES>100 mg/l) et presente un cycle saisonnier regulier. Lors des crues, l'arsenic et le mercure dissous sont dilues et les teneurs dans les suspensoides de tous ces elements diminuent. Les medianes des valeurs des Kd (Coefficients de distributions) sont equivalentes a celles trouvees sur d'autres fleuves (*104 ) : As = 0,8, Cd = 16,3, Hg = 49,7, Pb = 44,7, Cu = 9,5, Zn = 54. Les strategies de surveillance et de calcul des flux polluants doivent etre adaptees aux variations de chacun des elements.

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D. Cossa

Papers

Comportements des contaminants en trace dissous et particulaires (As, Cd, Cu, Hg, Pb, Zn) dans la Seine