منشاء‌يابي هيدروكربن‌هاي موجود در رسوبات سطحي سواحل خليج‌فارس در محدوده استان بوشهر با استفاده از نشانگرهاي زيستي آلكان نرمال

Source identification of hydrocarbons in surface sediment of the Persian Gulf in Bushehr province using n-alkane biomarkers

اﯾﻦ ﻣﻄﺎﻟﻌﻪ ﺑﺎﻫﺪف ﺗﻌﯿﯿﻦ ﻣﻨﺸﺄ ﻫﯿﺪروﮐﺮﺑﻦﻫﺎي ﻣﻮﺟﻮد در رﺳﻮﺑﺎت ﺳﻄﺤﯽ ﺳﻮاﺣﻞ ﺧﻠﯿﺞﻓﺎرس در ﻣﺤﺪوده اﺳﺘﺎن ﺑﻮﺷﻬﺮ ﺑﺎ اﺳﺘﻔﺎده از ﻧﺸﺎﻧﮕﺮﻫﺎي زﯾﺴﺘﯽ آﻟﮑﺎنﻫﺎي ﻧﺮﻣﺎل در ﺳﺎل 1397 اﻧﺠﺎم ﺷﺪ. ﺟﻬﺖ اﻧﺠﺎم اﯾﻦ ﺗﺤﻘﯿﻖ 8 اﯾﺴﺘﮕﺎه اﺻﻠﯽ و از ﻫﺮ اﯾﺴﺘﮕﺎه اﺻﻠﯽ 3 ﻧﻘﻄﻪ ﺟﻬﺖ ﻧﻤﻮﻧﻪﺑﺮداري اﻧﺘﺨﺎب ﮔﺮدﯾﺪ. ﻧﻤﻮﻧﻪﻫﺎ از رﺳﻮﺑﺎت ﺳﻄﺤﯽ )0 - 5 ﺳﺎﻧﺘﯽﻣﺘﺮ( در 24 ﻧﻘﻄﻪ ﻣﻨﺘﺨﺐ ﻧﻮار ﺳﺎﺣﻠﯽ اﺳﺘﺎن ﺑﻮﺷﻬﺮ ﺑﺮداﺷﺖ ﮔﺮدﯾﺪ. آزﻣﺎﯾﺶﻫﺎي ﻣﻮردﻧﻈﺮ در اﯾﻦ ﺗﺤﻘﯿﻖ روي ﻫﺮ ﻧﻤﻮﻧﻪ ﺑﺎ 3 ﺑﺎر ﺗﮑﺮار اﻧﺠﺎم ﺷﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﺑﯿﺸﺘﺮﯾﻦ ﻣﯿﺰان رس در ﻧﻤﻮﻧﻪ رﺳﻮب ﻣﻨﻄﻘﻪ ﺑﻬﺮﮔﺎن )62 درﺻﺪ( و ﮐﻤﺘﺮﯾﻦ آن در ﻧﻤﻮﻧﻪ رﺳﻮب ﻣﻨﻄﻘﻪ ﻧﺎﯾﺒﻨﺪ )28 درﺻﺪ(، ﺑﯿﺸﺘﺮﯾﻦ ﻣﯿﺰان ﺳﯿﻠﺖ در ﻧﻤﻮﻧﻪ رﺳﻮب ﻣﻨﻄﻘﻪ ﻣﻨﺪ )34 درﺻﺪ( و ﮐﻤﺘﺮﯾﻦ آن در ﻧﻤﻮﻧﻪ رﺳﻮب ﺑﻨﺪر ﮔﻨﺎوه )23 درﺻﺪ( و ﺑﯿﺸﺘﺮﯾﻦ ﻣﯿﺰان ﺷﻦ در ﻧﻤﻮﻧﻪ رﺳﻮب ﺑﻨﺪر ﻋﺴﻠﻮﯾﻪ )45 درﺻﺪ( و ﮐﻤﺘﺮﯾﻦ آن در ﻧﻤﻮﻧﻪ رﺳﻮب ﺑﻨﺪر ﺑﻬﺮﮔﺎن )13 درﺻﺪ( ﻣﯽﺑﺎﺷﺪ. ﻣﺤﺪوده ﻣﻮاد آﻟﯽ ﮐﻞ ﻧﯿﺰ در ﻧﻤﻮﻧﻪﻫﺎي رﺳﻮب 3) 18/8-GP-2) 264/4 -(AP( ﻣﯿﻠﯽﮔﺮم ﺑﺮ ﮔﺮم وزن ﺧﺸﮏ ﺗﻌﯿﯿﻦ ﮔﺮدﯾﺪ )ﻣﯿﺎﻧﮕﯿﻦ = 47/7±52(. ﻧﺘﺎﯾﺞ اﻧﺪازهﮔﯿﺮي ﺗﺮﮐﯿﺒﺎت آﻟﮑﺎن ﻧﺮﻣﺎل ﺑﺎ اﺳﺘﻔﺎده از دﺳﺘﮕﺎه ﮐﺮوﻣﺎﺗﻮﮔﺮاﻓﯽ ﻧﺸﺎن داد ﮐﻪ ﺑﯿﺸﺘﺮﯾﻦ ﻣﯿﺰان آﻟﮑﺎن ﻣﺮﺑﻮط ﺑﻪ اﯾﺴﺘﮕﺎه ﮔﻨﺎوه-2) 2-GP( ﺑﺎ220626 ﻣﯿﮑﺮوﮔﺮم ﺑﺮ ﮔﺮم وزن ﺧﺸﮏ و ﮐﻤﺘﺮﯾﻦ ﻣﯿﺰان ﻣﺮﺑﻮط ﺑﻪ اﯾﺴﺘﮕﺎه ﻋﺴﻠﻮﯾﻪ-3) 3-AP( ﺑﺎ 404 ﻣﯿﮑﺮوﮔﺮم ﺑﺮ ﮔﺮم وزن ﺧﺸﮏ رﺳﻮب ﻣﯽﺑﺎﺷﺪ. آﻧﺎﻟﯿﺰ وارﯾﺎﻧﺲ ﯾﮏﻃﺮﻓﻪ ﻧﺸﺎن داد ﮐﻪ ﻣﯿﺰان ﻣﻮاد آﻟﯽ ﮐﻞ و ﺗﺮﮐﯿﺒﺎت آﻟﮑﺎن در رﺳﻮﺑﺎت اﯾﺴﺘﮕﺎهﻫﺎي ﻣﺨﺘﻠﻒ داراي اﺧﺘﻼف ﻣﻌﻨﯽدار ﻣﯽﺑﺎﺷﺪ )0/05≤P(. ﻣﯿﺰان آﻟﮑﺎن در رﺳﻮﺑﺎت ﻣﻮردﻣﻄﺎﻟﻌﻪ ﻧﺸﺎن داد ﮐﻪ ﺑﺮ اﺳﺎس ﻣﻌﯿﺎر ﺑﯿﻦاﻟﻤﻠﻠﯽ رﺳﻮﺑﺎت ﺑﻪﺷﺪت آﻟﻮده ﻣﯽﺑﺎﺷﻨﺪ. ﺟﻬﺖ ﺗﻌﯿﯿﻦ ﻣﻨﺸﺄ آﻟﮑﺎنﻫﺎي ﻧﺮﻣﺎل از ﺷﺎﺧﺺﻫﺎي CPI )0-2/1( و ﺑﯿﻮﻣﺎرﮐﺮﻫﺎﯾﯽ ﻧﻈﯿﺮ Ph/n-C18 ،(3/0-6/4) Pr/n-C17 ،(0-2/1) Pr/Ph )3/0-7/2(، LMW/HMW )1/0-5/1( و U/R )75/10-1/3( اﺳﺘﻔﺎده ﮔﺮدﯾﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﻫﯿﺪروﮐﺮﺑﻦﻫﺎي ﻣﻮﺟﻮد در رﺳﻮﺑﺎت ﺳﻄﺤﯽ ﻣﻨﻄﻘﻪ ﻣﻮردﻣﻄﺎﻟﻌﻪ ﻣﻨﺸﺄ ﭘﺘﺮوژﻧﯿﮏ )ﻧﻔﺘﯽ( دارﻧﺪ ﮐﻪ ﻣﻤﮑﻦ اﺳﺖ ﻧﺎﺷﯽ از ﻧﺸﺖ ﻣﻮاد ﻧﻔﺘﯽ از ﺧﻄﻮط اﻧﺘﻘﺎل ﻧﻔﺖ ﺧﺎم، ﻧﺸﺖ از ﺳﮑﻮﻫﺎي ﺑﻬﺮهﺑﺮداري ﻧﻔﺖ ﺧﺎم، ﺗﺮدد ﻧﻔﺖﮐﺶﻫﺎ و ﻋﻮاﻣﻞ دﯾﮕﺮ ﺑﺎﺷﺪ.

This study aimed to determine the origin of hydrocarbons in surface sediment of the Persian Gulf coasts in Bushehr province using n- alkane biomarkers in 2018. For this purpose, 8 main stations and 3 points from each main station were selected for sampling. The samples were collected from surface sediments (0-5 cm) at 24 selected points of coastal zone of Bushehr province. Experiments in this study were performed on each sample with 3 replications. The results showed that the highest clay content was found in Bahregan port sediment sample (62%) and the lowest in Naiband sediment sample (28%), the highest silt content in Mond sediment sample (34%) and the lowest in Genaveh port sediment sample (23%) and the highest amount of sand in the sediment sample of Asalouyeh port (45%) and the lowest in the sediment sample of Bahregan port (13%). Total organic matter (TOM) content was also determined in sediment samples 18.8 (AP-3) - 264.4 (GP-2) mg/g dry weight (mean=47.7±52). The results of measurement of n-alkanes by gas chromatography (GC-MS) showed that the highest n-alkanes belonged to Genaveh-2 (GP-2) with 220626 μg/g dry weight and the lowest to Asalouyeh-3 (AP-3) with 404 μg/g dry weight. One-way ANOVA showed that the amount of total organic matter and n-alkane compounds in sediments of different stations was significantly different (P≤0.05). The amount of n-alkanes in the studied sediments showed that they are highly contaminated according to the international criteria. To determine the source of n- alkanes from CPI indices (0.1-2) and biomarkers such as Pr/Ph (0.1-2), Pr/n-C17 (0.4-3.6), Ph/n-C18 (0.2-3.7), LMW/HMW (0.1-1.5) and U/R (10.3-75.1) were used. The results showed that the hydrocarbons in the surface sediments of the study area are of petrogenic origin, which may be due to oil leakage from crude oil pipelines, leakage from petroleum exploitation platforms, oil tanker traffic and other factors.