River basin metal pollution originates from heavy industries (plating, automobile) and from urban sources (Paris conurbation: 2740 km(2), 9.47 million inhabitants). The natural sources of metal have been found to be limited due to sedimentary nature of this catchment and to the very low river sediment transport (10 t km(-2) y(-1)). Several types of data have been collected to build the metal budget within the whole Seine River basin: field surveys, economical statistics and environmental models. Environmental contamination and related fluxes have been measured on atmospheric fallout, rural streams particles, and Seine River particles upstream and downstream of Paris and at river mouth. Metal pathways and budgets have been set up for (i) a typical cultivated area, (ii) a Paris combined sewer system, (iii) Paris conurbation and (iv) the whole catchment metal retention effect in floodplain and dredged material. Metal fluxes to the estuary have been decomposed into natural, urban domestic and other sources. The latter are within 1-2 orders of magnitude larger than waste water fluxes directly released into rivers according to an industrial census. These fluxes have been further compared to the annual use (1994-2003) of these metals. Metal excess fluxes exported by the river are now a marginal leak of metal inputs to the catchment (i.e. "raw" metals, metals in goods, atmospheric fallout), generally from 0.2 to 5 per thousand. However, due to the very limited dilution power in this basin, the contamination of particles is still relatively high. The Seine River basin is gradually storing metals, mostly in manufactured products used in construction, but also in various waste dumps, industrial soils, agricultural and flood plain soils.

Runoff was collected from 4 roofs, 3 courtyards and 6 streets on an experimental catchment in central Paris, and analysed for SS, VSS, COD, BOD5, hydrocarbons, heavy metals both as regards dissolved and particle fractions. Whereas street runoff showed important SS, COD and hydrocarbon loads, roof runoff was noticeable for its high concentration of heavy metals. These concentrations in comparison with water quality standards enhance the importance of runoff pollution. The use of sample settling for runoff treatment is discussed on the basis of data concerning the distribution between dissolved and particle bound pollution loads, along with settling velocity measurements. Runoff particles were found to be highly contaminated with heavy metals and hydrocarbons, which raised the problem of sludge disposal.