MAP Technical Reports Series No. 106 UNEP

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In conclusion, the procedures for estimating nutrient exports from basins as discussed
above are largely supported by the Italian experience. Still, it remains questionable how far the
respective findings and methodologies can be transferred to other Mediterranean countries.
There are several factors that differ substantially from country to country: population density and
its regional variations, land use distribution and agronomic utilization such as prevailing
agricultural crops, fertilizer use on crop land, and animal husbandry, the latter being rather
extensive in many Mediterranean regions. It would therefore be inappropriate to extend the above
model approach to single Mediterranean countries or the Mediterranean as a whole without
substantial modifications. As there are essential difficulties to do this properly, several alternative
methods are used in the following to determine the range and limits within which the actual
figures of the nitrogen and phosphorus load from land-based sources to the Mediterranean may
lie.
4.5 Load assessment for the Mediterranean as a whole
The assessment of the nutrient load for the Mediterranean as a whole encounters major
difficulties due to the lack of comparable data for the whole area. Therefore, a step by step
approach is taken using substantially simplified methodologies. This entails (1) a general
pollution and sensitivity index, (2) a review of the Italian attempt to asses its total load, and (3)
a generalized methodology for estimating the probable range within which the total nitrogen and
phosphorus load to the Mediterranean is to be expected.
a) Potential pollution and sensitivity index
Prior to embarking on the difficult question, how much nitrogen and phosphorus is
discharged into the Mediterranean a simplified overview approach is taken that pinpoints areas
of major concern, and that will be supplemented by concrete data about eutrophication incidents
in Chpt. 5.
For this purpose a simple index that has bearing on potential regional and local
consequences of population on nutrient loads and eutrophication is introduced. This index is
defined as the number of inhabitants per km of shoreline and, accordingly, represents a coarse
measure of coastal nutrient load density. Using population and shore length figures as listed in
Table 6, this index is calculated for all Mediterranean countries and would range from 400 for
Yugoslavia to 17,400 for Egypt.
Interpretation of these figures is not straight forward, however. Depending on how the
figures on shoreline length and the number of inhabitants that weigh directly on the sea have
been estimated in the first place, the index can be open to considerable uncertainty, as within
countries there is large variation in the distribution of population, and hence, variation in
inhabitant/shoreline density. As example the Italian figure of 5,300 taken at face value, would be
entirely misleading, particularly as regards the Adriatic Sea. Of the 57 million inhabitants of the
20 administrative Regions about 24 million residing in the 7 Northern Regions: Piemonte, Valle
d'Aosta, Lombardia, Emilia-Romagna, Trentino Alto Adige, Veneto, Friuli Venezia Giulia, weigh
on the North Adriatic coast of roughly only 400 km; this gives an inhabitant/shoreline density of
about 60,000, the highest in the whole Mediterranean. Accordingly, the inhabitant/shoreline
density for the rest of Italy would reduce to about 4.5.
Similarly in Greece e.g., the corresponding density of the Gulfs of Saronikos and
Thermaikos, and else where would result substantially higher than the national average, and
probably the same is true for coastal stretches of countries like Turkey, Tunisia etc. On the