『Abstract
This study presents a detailed discrimination between the natural
and anthropogenic sources of dissolved major elements in the Tet（eの頭に＾） River, a typical small coastal river in
the south of France. The main objectives were to quantify the
materials that were released by human activities in the basin,
and to determine the specific element inputs for the major land
use forms. The dissolved material fluxes were estimated by weekly
monitoring over a hydrological year (2000-2001) along the major
water gauging stations, and the flux relationships were examined
in the context of anthropogenic and natural basin characteristics
as determined by a Geographical Information System (GIS). Intensive
agricultural land use in the form of fruit tree cultures and vineyards
has a strong control on the dissolved element fluxes in the river.
Area specific element releases for these cultures are greater
for SO4, with an estimated average of about
430 ±18 keq km-2 a-1. This is ≧11 times
the natural SO4 release by rock weathering.
Also for K, NO3, PO4
and Mg, the specific releases were ≧6 times the natural weathering
rates (respectively about 44, 60, 4 and 265 keq km-2
a-1). Waste-waters are the other major source of anthropogenic
elements in the river. They have an important role for the fluxes
of inorganic P and N, but they are also a considerable source
of Cl and Na to the river. For example, the average annual release
of Cl is around 150 moles/inhabitant in the rural basin parts.
Further downstream, however, where population density strongly
increases, industrial effluents can enhance this value (＞300 moles/inhabitant).
The waste-waters contribute more than 70％ of the dissolved inorganic
N export to the sea, although their contribution to the average
DOC export is almost negligible (3％).』
1. Introduction
2. Data and methods
2.1. Sampling and water fluxes
2.2. Analytical methods and flux calculations
2.3. Quantification on non-weathering sources
2.4. Average rainwater composition
3. Results
3.1. Land use and general basin characteristics
3.2. Major element fluxes
3.3. pH, alkalinity and pCO2
4. Discrimination of the major element sources
4.1. Atmospheric inputs
4.2. Road salting
4.3. Average waste-water composition
4.4. Discriminating between waste-water and fertilizer inputs
4.5. Rock weathering
4.6. Nutrient fluxes (Si, N, P)
4.7. Dissolved organic carbon
5. Element releases by human activities
5.1. Agriculture
5.2. Waste-waters
6. Conclusions
Acknowledgements
References