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ENVIRONMENTAL IMPACT STUDY
Rn: 03-033 CONTAINER TERMINAL PLOCE PAGE: 53
at station P4 situated in front of the Prapatno bay on the Pelješac Peninsula,
i.e. at the outer side of the Neretvanski Channel: 14 – 25 m.
April July September December
Temperature, º C 14.18 – 17.06 16.16 – 26.20 17.44 – 23.43 13.7 – 17.21
Salinity, psu 32.28 – 38.57 34.93 – 38.93 34.53 – 38.69 36.72 – 38.51
Density (s t) kg/m 3 23.41 – 28.81 22.98 – 28.70 23.93 – 28.39 27.42 – 28.18
Table 1. Ranges of main hydrographical parameters in the Neretvanski Channel (3 stations) during the year 2002:
The presence of dissolved nutritious salts, i.e. salts of nitrogen, phosphorus
and silicon are a precondition for primary production of organic matter.
However, their excessive amount (brought by rivers or by waste waters) may
cause eutrophication of a certain area, with unfavourable impact on the sea
ecosystem and on aesthetical properties of the sea water.
The sea of the Neretvanski Channel in the year 2002, as well as in the
preceding years, can be classified as an area of low concentration of
nutritious salts. The sea, in the area influenced by the Neretva river (stations
P1, P2 and P3) contains higher concentrations of salts of inorganic nitrogen
and orthosilicate in relation to the outer side of the Channel (station P4), while
values are opposite for orthophosphate. The only exception is the station P1,
situated in front of the town port in Ploce, where the surface layer is often
enriched by orthophosphate.
In the whole investigated area, water column saturation by oxygen was
appropriate; it ranged within narrow limits. On the station in front of the Ploce
town port (P 1) vertical profile of saturation by oxygen shows a uniform
distribution by depth, without enrichment in the surface layer or reduction in
the bottom layer.
Trophic (nutritional) degree of an area is very well reflected through the height
of primary production of organic matter (the first step in transformation of
inorganic material into a living organic matter). Each disturbance of the sea
ecosystem balance is first reflected at the first step of the food chain, so that,
by following the primary production, an appropriate insight into the integral
state of the sea ecosystem can be obtained. The primary production has been
examined by determination of biomass (chlorophyll a) and the phytoplankton
community structure.
In the area of Ploce, the overall situation can be considered very favourable,
as chlorophyll concentrations (amount of biomass) range between values
characteristics for channel waters and open waters of the Adriatic. Qualitative
composition of the phytoplankton community is marked by predominance of
diatomaceaes, although in summer period dinoflagellates were proportionally
well represented too. In this area no important water bloom was noticed in the
year 2002.
Contamination by faecal waters was examined by determining bacteria
indicators of the faecal pollution. The sea at the station P1, in front of the
Ploce port, was only lightly polluted, i.e. it satisfied the criterion imposed for
the sea intended for bathe and recreation.
RIJEKAPROJEKT d.o.o.