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vol-14“0” LIMNOL’OOICAL STUDIES ON TJIH NILE WATER
A’J CAIRO, EGYPT.
ABpEL EL-SAMIE ELEWA· AND HESijIJO;M MAHDI”
*I~titute of Oceanography and Fisheries.
**F)culty of Science, Al-Azhar University, C.iro.
ABSTBACT
Regional varfations of s~ physical and ch.lcal
conditions in the Nile water at Cairo …. studted.
The water temperature reac~ed a maxtl:lUlll ‘Vllue Of
31 “c tn the surface layer in sUllllll!r and , .inl~
of 16 “c tn Winter. Transparency vlluel .re higher
in the cold season (85 CII!) and lower in the hot
period (50 cm). At the some time, tt Increlsed
northward from Helwan reaching tts highest .Iluel
at Roud El-Farag. However suspended ~oltds vlrled
tn the opposit direction. Dtssolved oxygen showed
.axilll\llll concentration in oJalluny and lowest vllues
In July. The higher oxyge~ concentration It Roud
El-Farag in the surface water (11.5 1Ilg/1) WIS
accompanied by higher transp_rency and lower suspended
matter. The minimum oxygen content (6.3 Mg/l) ..asu…d
at Helwan may be due to oxygen consUlllPtton In the
decomposition of organic llII~ter. The chemical oxygen
dellllnd had the maximum values at Roud El-Flrag
(averages 26.1 and 27 mg/1) jn the surflce end at
5 ‘” depth respectively, and lowest values at Helwan
(averages 23.4 and 24.4 mg/l) tn the surface and
5 III depth respectively. COD gave a IlIIXlmuM In January
(averaves 28.7 and 30.1 mg/l) for the lurface Ind
5 II depth respectively. The levels of 800 tn the
study area showed a trend s1_tlar to that of COO.
Bicarbonate content varted seuonilly Ind
regionally with maximum val”es tn OCtober at Helwln
Ind the IItnilRUlR tn Jallulry at Roud El-Farag.
Chlorosity varied seasonally wtth htghest vilues
in July (averages of 26 and 23.7 lIIg/l for surface
and !5 II depth and lowest of 10.6 lllJ/l In January
and also regionally to reach a htgher value of 20.8
lllJ/l It Helwan and 18.6 ,,/1 tn the lurface .tar
at Roud El-Farag. The sJight Irregular varl.tlon
In pH valuel can be attributed ..Inlyto .Ixlng
of the Nile water. CalciUM .nd Magnellu. dtstrlbuttons
have the same trend II .hOWll tn concentration of
HC03 The ..xt~ value of electrlc.l conductivity
380 \llllhos lIeasured at Hel.,,, 1″ July and the .1n1_
of 310 ~os at El-Rodah tn Qctober.
