NITROGEN AND PHOSPHORUS SPECIES OF LAKE BURULLUS WATER (EGYPT)

NITROGEN AND PHOSPHORUS SPECIES OF LAKE
BURULLUS WATER (EGYPT)
MOHAMED ABD EL-AZIZ OKBAH
National Institute of Oceanography and Fisheries, Alexandria, Egypt
Key words: Lake Burullus, Nutrients, Nitrogen, phosphorus forms.
ABSTRACT
Water samples collected from Lake Burullus were analyzed to investigate temporal and
spatial variations of phosphorus and nitrogen species during the period from January to
October 2003. The concentrations of dissolved inorganic nitrogen (DIN), dissolved organic
nitrogen (DON), particulate nitrogen (PN) and total nitrogen (TN) were in the ranges of
4.10-107.51µmole l
-1
; 7.43-170.10µmole l
-1
; 9.33-209.4µmole l
-1
and 51.40-259.0
µmole l
-1
respectively. DIN, DON and PN species represent 19%, 34% and 47% of the
total nitrogen content, respectively.
Significant variations for the concentrations of the phosphorus forms have been found
in this study. Concentrations of reactive phosphate (PO4), dissolved organic phosphorus
(DOP), particulate phosphorus (PP) and total phosphorus (TP) were in the ranges of 0.76-
8.40µmole l
-1
, 0.27-10.74µmole l
-1
, 0.26-12.81µmole l
-1
and 3.40-21.42µmole l
-1
,
respectively. The study showed that high percentage of total phosphorus exists in the forms
PP and DOP (74.1%), in addition, low levels of PO4 during spring (0.91µmole l
-1
) and
summer ( 0.94µmole l
-1
). The middle basin of the lake revealed higher level of phosphorus.
P: N ratios were recorded lower values (1:7 to 1:10) compared with that reported by
Redfield’s ratio (1:16), revealing low nitrogen content in comparison with phosphorus.