as an efficiency indicator of the capacity of a given society to recycle its metals. It
has dramatically decreased for all metals since 1950 (e.g. from 0.8 to 0.05% for Cu),
except for Hg, which remains at a high ratio, around 10% of leaks. The metal
exported fluxes calculated from core data are therefore powerful tools to observe
the general decontamination trend in Europe, which can be linked to the local type of
economy and environmental policies, defining the trajectory of a given environmental issue [74]. In the Seine River basin, the location of recycling facilities is a key
control factor in contamination by metals [33]. The recycling process (collection of
used metal-containing devices and their retreatment outside of the Seine River basin
and often outside France, i.e. a kind of pollution delocalisation [36]) seems to have
been effective mostly after 1980.
As pointed out in Sect. 2, this leakage estimation is based on several hypotheses:
(1) all river particles have the same age; (2) their age is very recent – a few years on
average – so that the average export at time t Æ a few years can be compared to the
circulation data for the same period. When there is evidence that the river particles
have extended age ranges or that they have greater ages, these hypotheses are not
valid. In the Seine River, the floodplain deposits are relatively fine (silt), so that their
average transit time throughout the river network ranges from a few weeks (large
floods) to a few years. The occurrence of antibiotics in core sediment (Fig. 6) within
1 year after first arriving on the market and the decline of DDT metabolite, which
started with the ban of this insecticide in France, suggest a rapid reaction of Seine
River fine sediment (median grain size in the silt fraction) to source changes. In
contrast, coarser material (1 cm) travels in the Seine River at secular rates: gravels
contaminated by iron smelting during the eighteenth century have actually been used
to study the very slow bedload movement in the Upper Marne (see [75], box 1).
7.2 Intercomparison of River Contaminant Fluxes
in Relation to Their Population in Western European
Rivers
The excess load of metals and the load of micropollutants can be rated by the
population of river basins, to generate the per capita excess load (ELcap), an
indicator also used for major ions or nutrients to compare and scale these per capita
loads to economic indicators, such as per capita energy consumption [51, 76]. For
metals, the comparison of the per capita loads for Western European rivers, the St
Lawrence, Mississippi and Danube rivers, at the period of their maximum contamination level near 1970 (Table 2A) showed similar orders of magnitude for each
metal, suggesting the existence of a metal metabolism common to these old industrial countries for similar levels of development and environmental regulations
[70, 72]. Based on the metal content, the general pressure ranking is Zn ) Pb !
Cu > Cr > Ni > Cd ¼ As > Hg, but their maximum EFs in river particulates are
completely reversed: Hg > Cd > Pb > Zn. When looking in greater detail, each
Sedimentary Archives Reveal the Concealed History of Micropollutant. . .
291
has dramatically decreased for all metals since 1950 (e.g. from 0.8 to 0.05% for Cu),
except for Hg, which remains at a high ratio, around 10% of leaks. The metal
exported fluxes calculated from core data are therefore powerful tools to observe
the general decontamination trend in Europe, which can be linked to the local type of
economy and environmental policies, defining the trajectory of a given environmental issue [74]. In the Seine River basin, the location of recycling facilities is a key
control factor in contamination by metals [33]. The recycling process (collection of
used metal-containing devices and their retreatment outside of the Seine River basin
and often outside France, i.e. a kind of pollution delocalisation [36]) seems to have
been effective mostly after 1980.
As pointed out in Sect. 2, this leakage estimation is based on several hypotheses:
(1) all river particles have the same age; (2) their age is very recent – a few years on
average – so that the average export at time t Æ a few years can be compared to the
circulation data for the same period. When there is evidence that the river particles
have extended age ranges or that they have greater ages, these hypotheses are not
valid. In the Seine River, the floodplain deposits are relatively fine (silt), so that their
average transit time throughout the river network ranges from a few weeks (large
floods) to a few years. The occurrence of antibiotics in core sediment (Fig. 6) within
1 year after first arriving on the market and the decline of DDT metabolite, which
started with the ban of this insecticide in France, suggest a rapid reaction of Seine
River fine sediment (median grain size in the silt fraction) to source changes. In
contrast, coarser material (1 cm) travels in the Seine River at secular rates: gravels
contaminated by iron smelting during the eighteenth century have actually been used
to study the very slow bedload movement in the Upper Marne (see [75], box 1).
7.2 Intercomparison of River Contaminant Fluxes
in Relation to Their Population in Western European
Rivers
The excess load of metals and the load of micropollutants can be rated by the
population of river basins, to generate the per capita excess load (ELcap), an
indicator also used for major ions or nutrients to compare and scale these per capita
loads to economic indicators, such as per capita energy consumption [51, 76]. For
metals, the comparison of the per capita loads for Western European rivers, the St
Lawrence, Mississippi and Danube rivers, at the period of their maximum contamination level near 1970 (Table 2A) showed similar orders of magnitude for each
metal, suggesting the existence of a metal metabolism common to these old industrial countries for similar levels of development and environmental regulations
[70, 72]. Based on the metal content, the general pressure ranking is Zn ) Pb !
Cu > Cr > Ni > Cd ¼ As > Hg, but their maximum EFs in river particulates are
completely reversed: Hg > Cd > Pb > Zn. When looking in greater detail, each
Sedimentary Archives Reveal the Concealed History of Micropollutant. . .
291