Seasonal Variations for Petroleum Hydrocarbons in the Tissues of Fishes from Shatt Al-Arab River and Southern Iraqi Marshes (2020)

Abstract

Petroleum hydrocarbons were investigated in the tissues of five fish species: (1) Carrasius auratus,  (2) Coptodon zillis, (3) Oreochromis auratus, (4) Oreochromis niloticus, and (5) Tenualosa ilisha,   caught at three stations : 1) El-Manthory within Al-Hammar marshland, and  2) Sinbad Island, and 3) Basrah station along  Shatt Al-Arab River during the year 2020. Fishes were caught by net , kept in cool box on the board of fishing boat, then transferred to the labs of  Marine Science Centre / Basrah University, cleaned and  frozen at – 20^oC prior to analysis. In the lab fishes were thawed and cut from their sides. Tissues were freeze dried by Edwards freeze drier type  Modulyo, homogenized and 10 grams were weighted from each fish, petroleum hydrocarbons were extracted in hot soxhelet by using 40 ml n- hexane solvent for 4 hours .  Extracts were reduced to 10 ml each by rotary evaporator. Finally concentrations of petroleum hydrocarbons in each sample were estimated spectrofluorometricaly by UV spectrofluorometry type Shimadzu  RF-530IPC at excitation wavelength 310 nm and emission wavelength 360 nm. Higher levels were recorded during winter and spring in fishes caught at Shatt Al-Arab River, Stations 2 and 3, while lower levels were recorded in  Tenualosa ilisha caught at all stations during spring, increased during summer, then autumn and winter . levels recorded in ?g/g dry weight were in the trend ND < 2.15 < 5.33 ? 4.51 respectively at Sinbad Island site No. 2,  ND < 3.09 < 9.18 < 11.64 respectively at Basrah site No 3, and ND < 1.14 < 6.73 < 8.46 respectively at Manthory site No. 1. These levels were comparable to levels reported in fishes  studies at nearby  areas.