CC BY
3EARTH SCIENCES
ECOLOGICAL ASSESSMENT OF SOIL HYDROCARBON POLLUTION BY MEASURING
MAGNETIC SUSCEPTIBILITY
Novruzov Z., Garayeva T., Bagirova A., Aliyev Z.
Institute of Geology and Geophysics, Ministry of Science and Education,
Republic of Azerbaijan DOI: 10.5281/zenodo.7479698
ABSTRACT
In this work, the magnetic susceptibility (%) of soils in situ was measured on the Pirallahi Island Oil Area. Pirallahi Island Oil Area is located near the Absheron Peninsula of Azerbaijan (Fig.1). In order to compare the results of measurements of the magnetic susceptibility of hydrocarbon (HC) -contaminated soils in situ, the ones of the HC of the hydrocarbon-free Dubendi site located on the mainland were also carried out. As a result of comparison of x measurements, a difference in readings was revealed in both areas. Thus, the influence of hydrocarbons on the change in magnetic susceptibility measured on two similar areas is obvious. This clearly indicates a change in the association of magnetic minerals in soils exposed to hydrocarbons. It follows from the above that, using measurements of the magnetic susceptibility of soils in situ, we can detect areas contaminated with hydrocarbons. In the future, when using magnetic susceptibility and other magnetic parameters measured in bottom sedimentary rocks, they can be used as a new search feature for oil and gas deposits.
Keywords: magnetism, magnetic susceptibility, hydrocarbons, anthropogenic pollution.
The work was carried out with the financial support of SOCAR, Republic of Azerbaijan.
Introduction. Environmental pollution by organic pollutants (soil, reservoirs, sediments) is an important global environmental problem. To assess and restore the environment contaminated with HC, a method is needed that takes much less time and is affordable. The eco-magnetic method of environmental monitoring has a high potential due to its high sensitivity [1]. Recently, studies of soil contamination with heavy metals have switched to ecomagnetic methods. In this matter, the eco-magnetic method has proven itself perfectly [2].
However, there has not yet been enough scientific research to study the relationship between magnetic properties and organic pollutants. Hanesh and Holger [3] in Leoben (Austria), studying the soils of a metallurgical plant, noticed a correlation between polycyclic aromatic hydrocarbons and magnetic susceptibility. Morris et al. [4] after analyzing the core samples came to the conclusion that magnetic sensitivity can be a reliable and inexpensive method for determining the degree of contamination of sediments. Liu et al. [5] studying the Mavanmiao oil field (Jianghan Basin, China), we observed an increase in some magnetic parameters (magnetic susceptibility -% and full saturation magnetization - Ms) in oil reservoirs.
Thus, we conclude that magnetic properties, especially magnetic susceptibility, can be measured in a very short time and can be used as a convenient method for determining areas not contaminated with HC. The main purpose of this study is to detect areas of soil contaminated with hydrocarbons on Pirallahi Island by measuring their magnetic susceptibility.
The rich oil and gas deposits discovered in Azerbaijan belong to the productive strata (net pay), widespread and well-studied. On the territory of the island there are both exploited wells and wells that have ceased their operational activity. Our goal is to identify soil contamination with hydrocarbons by the magnetic method as much as possible.
Field measurements of magnetic susceptibility Pirallahi Island is located to the east of the Absheron Peninsula, 50 km from Baku (Fig. 1). For more than a hundred years, oil extracted from wells has been polluting the environment. In the study area, the magnetic susceptibility of soil contaminated with hydrocarbons was measured at three levels from the soil surface. The study area of Pirallahi Island covers both the sites of active oil wells and the sites of old abandoned (inactive) wells in the past. The locations of magnetic susceptibility measurements were accurately fixed by CPS measurements (Table 1). The magnetic susceptibility (x) was measured with a field magnetic susceptibility meter (Kappameter model KT-5).
Figure 1. The Pirallahi island and Dubendi studied area for hydrocarbon pollution.
Table 1.
CPS values of measurement points x of Pirallahi Island.
Sequential number Sample number Geographical bearings
latitude longitude
1 001 40°28'40.29" 50°19'52.51"
2 002 40°28'53.40" 50°19'53.80"
3 003 40°28'34.68" 50°20'13.31"
4 004 40°28'24.63" 50°19'40.93"
5 005 40°28'39.74" 50°19'38.37"
6 006 40°28'20.15" 50°20'20.63"
7 007 40°28'4.76" 50°20'19.16"
8 008 40°27'43.20" 50°20'49.45"
9 009 40°27'25.96" 50°20'37.79"
10 010 40°27'12.54" 50°20'46.65"
The values of magnetic susceptibility from 10 points of the polluted area were measured from the study site. Preliminary data were obtained on the presence or absence of magnetic minerals in the collected samples.
The magnetic susceptibility measurement site (point 001) was carried out at a point with coordinates latitude 40028'40, 29" and longitude 50019'52, 51". The magnetic susceptibility x = 0.74x10-3 m3/kg was measured on the surface. At the same point at a depth of 10 cm, the measured magnetic susceptibility x= 0.26 x10-3 m3/kg. Also at this point, only at a depth of 30 cm, the measured magnetic susceptibility x = 0.31x10-3 m3/kg. Point 002 was measured from the north side of the study area, the coordinates of which are 40028'53.40" in latitude and 50019'53.80'' in longitude. The magnetic susceptibility x = 0.17x10-3 m3/kg was measured on the surface. At the same point at a depth of 15 cm, the magnetic susceptibility x = 0.09*10-3 m3/kg was measured. Also, at the same point, only at a depth of 40 cm, there was a change in the magnetic susceptibility x = 0.10 x 10-3 m3/kg. The magnetic susceptibility measurement site (point 003) was carried out at a point with coordinates latitude 40028'34, 68'' longitude 50020'13, 31''. Magnetic susceptibility measured on the surface x =
7.11xl0-3 m3/kg. Magnetic susceptibility measured at the same point only at a depth of approximately 10 cm x = 4.68x10-3 m3/kg. Nearby is an area 50 m wide and 100 cm long with high magnetic susceptibility. The magnetic susceptibility measurement point 004 was located near well No. 249, whose coordinates in latitude are 40028'24, 63'' and in longitude 50019'40, 93''. Measurements of magnetic susceptibility on the surface x =0.60x10-3 m3/kg. In the northwestern part of the island, the magnetic susceptibility was measured at point 005, whose coordinates are 40028'39, 74'' in latitude and 50019'38, 37'' in longitude. Magnetic susceptibility X =2.15x10-3 m3/kg measured on the surface. And the magnetic susceptibility x = 3.4x10-3 m3/kg was measured at a depth of 10 cm from the surface. Further, at the same point at a depth of 30 cm, the magnetic susceptibility x = 6.33x10-3 m 3/kg was measured. To the north of the place where we measured the magnetic susceptibility, it increases. As we approach well No. 1039 at 30-40 m, the magnetic susceptibility gradually decreases. The magnetic susceptibility measurement site (point 006) was carried out at a point with coordinates latitude 40028'20, 15'' longitude 50020'20, 63''. On the surface x = 1.88x10-3 m3/kg. At this point (the same co-
ordinates) at a depth of 15 cm, the magnetic susceptibility x = 0.24*10-3 m3/kg. The magnetic susceptibility measurement site (point 007) was carried out at a point with coordinates latitude 40028'4.76" longitude 50020T9.16". On the surface x =0.26x10-3 m3/kg. . At this point (the same coordinates) at a depth of 15 cm, the magnetic susceptibility x = 0.48*10-3 m3/kg and at a depth of 30 cm x = 0.08*10-3 m3/kg. The magnetic susceptibility measurement site (point 008) was carried out at a point with coordinates latitude 40027'43.20'' longitude 50020'49.45''. On the surface x =0.36x10-3 m3/kg. At this point (the same coordinates) at a depth of 15 cm, the magnetic susceptibility x = 0.06*10-3 m3/kg. The magnetic susceptibility measurement site (point 009) was carried out at the point with coordinates: latitude 40027'25, 96'' longitude 50020'37, 79''.
Conclusion. Thus, as a result of the conducted studies, there is an obvious relationship between soil pollution with hydrocarbons and an increase in magnetic susceptibility. In our opinion, this is due to the variable valency of iron. Iron, which is part of finely dispersed oxides and hydroxides, can participate in various chemical reactions. In particular, when hydrocarbons act on sedimentary rocks, they (hydrocarbons) can reduce iron oxides and hydroxides. Reduced iron contributes to the formation of new iron-containing compounds. That is, as a result of the impact of oil and gas on sedimentary rocks, newly formed magnetic minerals lead to an increase in magnetic susceptibility.
References
1. Petrovsky E, Ellwood BB (1999) Magnetic monitoring of air-, land- and waterpollution. In: Maher BA, Thompson R (eds) Quaternary climates, environments and magnetism. Cambridge University Press,
On the surface x =1.90x10-3 m3/kg. At this point (same coordinates) at a depth of 15 cm, the magnetic susceptibility x= 2.75 x 10-3 m3/kg and and at a depth of 20 cm X = 0.58x10-3 m3/kg. The magnetic susceptibility measurement site (point 010) was carried out at a point with coordinates: latitude 40027'12, 54" and longitude 50020'46, 65". On the surface x = 4.26x10-3 m3/kg. To compare the values of the magnetic susceptibility measured at the above points of the investigated area of Pirallahi, contaminated with hydrocarbons, we measured the values of the magnetic susceptibility of the Dubendi area, the surface of which was not contaminated with hydrocarbons. The bottom table shows the GPS values of the magnetic susceptibility measurement points in the Dubendi area with their x values.
Cambridge, pp 279-322.
https://doi.org/10.1017/CBO9780511535635.009.
2. Evans E.and Heller F. (2003). Environmental Magnetism: Principles and Applications of Enviromag-netics-book
3. Hanesch M, Scholger R (2002) Mapping of heavy metal loadings in soils by means of magnetic susceptibility measurements. Env Geol 42, pp 857-870. DOI: 10.1007/s00254-002-0604-1
4. Morris A & Robertson AHF (1993) 'Miocene remagnetisation of carbonate platform and Antalya complex units within the Isparta angle, SW Turkiye' TECTONOPHYSICS 220, (1-4) 243-266 Author Site , DOI
5. Liu, Q., Liu, Q., Chan, L., Yang, T., Xia, X., Cheng, T. 2006. ''Magnetic enhancement caused by hydrocarbon migration in the Mawangmiao Oil Field, Jianghan Basin, China'', Journal of Petroleum Science and Engineering, 53(1-2), 25-33.
Table 2.
CPS and x values measured in the Duyendy area.
Sample number Magnetic sceptibility Geographical bearings
latitude longitude
surface 15 sm below 30 sm below
01 2.69 0.18 40°24'8" 50°18'38"
02 0.18 0.13 40°24'1" 50°17'43
03 0.10 0.25 0.15 40°25'2" 50°17'21"
