The biological pump of carbon dioxide in El-Mex bay, Alexandria, Egypt

The biological pump of carbon dioxide in El-Mex bay, Alexandria,
Egypt
Thanaa H. Mahmoud*, Mamdouh S. Masoud**, Nayrah A. Shaltout* and
Nabila R. Hussien*
*National Institute of Oceanography and Fisheries, Alexandria
**Chemistry Department, Faculty of Science, Alexandria University
E-mail, [email protected]
Received 8th June 2009, Accepted 9th August 2009
Abstract
El-Mex Bay is a shallow sheltered estuary west of Alexandria extends between longitude 29o
47′ to 29o
50’E
and latitude 31o
7′ to 31o
9′. It receives a heavy load of waste water from El-Umum Drain, Sodium Bicarbonate and
Chloro Alkali Plant factories. Samples were collected during August (summer) 2004 from surface water of stations
I, VIII, IX and XII which represents water types of different salinity L, M1, M2 and D respectively. Environmental
variables such as, temperature, salinity, dissolved oxygen, carbon dioxide and total alkalinity concentrations were
measured. Gross primary production (GPP), community respiration (CR) and net community production of
phytoplankton (NCP) for El-Mex Bay were calculated. It is found that at water type “L” (station I) GPP values is the
lowest (45.37 mg C m–3h-1) and the highest at water type M1 (station IX). Community respiration (CR) content
varied between -282.3 mg C m–3h-1 to 167.38 mg C m–3h-1 at water types L and M2. Water type “L” could be
considered as heterotrophic system while water types M1, M2 and D are classified as autotrophic system. Net
community production (NCP) values varied between 147.89 mg C m–3h-1 at water type M2 and 327.71 mg C m3
h-1 at
water type M1.