Diagnostics of Oil Pollution Zones by
Electro-Physical Method
Sergey Prostov1*, and Evgeniy Shabanov1
1 T.F. Gorbachev Kuzbass State Technical University, 650000, 28 Vesennyaya St., Kemerovo, Russia
Abstract. The article presents the rationale and development of electro physical methods of control of the degree of soils pollution with petroleum products. The ranges of variation for the parameters of the pore space struc-ture and wettability for the Kuzbass conditions are determined by inverse calculations on the basis of experimental data. The theoretical dependences are shown which allow us to assess the degree of soil pollution with oil products according to the results of longitudinal and areal electrical sound-ing. The study confirms the possibility of rapid prediction of the degree of soil contamination by measuring its electrical resistance. The database has been compiled for interpretation of the results of experimental sounding when monitoring the changes in the degree of contamination. The use of the express forecast of numerical values of the contamination factor was studied.
1 Introduction
One of the most dangerous soil pollutants are petroleum products: lubricants and liquid fuel [1, 2]. The relevance of the problem of cleaning soils from oil pollution in mining industry (coal surface and underground mines, ore mines) due to large amounts of fuel consumption by road and rail transport, and lubricants in the operation of mining equipment, and tech-nical oils in electric power plants. The refined petroleum products contain toxic water-soluble fractions [3, 4], also, gasoline, and especially motor oils contain up to 20% of addi-tives, solvents, heavy metals. One liter of used oil may contaminate one million liters of water, not more than 60% of their volume being regenerated
One of the effective methods for managing the soil properties, especially of low perme-ability (filtration coefficient Kf < 10-8 m/s), is the method of electrochemical treatment [5, 6], its main impact on the contaminated soil being the electrical destruction of ecotoxicants and the electroosmotic displacement of the diluted pollutant in the area of mechanical re-moval (pumping). Experimental and theoretical bases of the electrochemical method were developed for the solution of problems of technical reclamation (drainage) and for stabiliz-ing the unstable waterlogged soils. The criteria for the rational use of this method are de-termined: the ratio of the coefficients of electroosmotic activity and filtration Ke/Kf > 107 and electrical resistance (SER specific electrical resistivity) ρ < 8 Ohm∙m.
Direct and indirect methods are applied to control the processes of cleaning of soils from pollution. Direct methods [7-9] (infrared spectrophotometry, ultraviolet luminescence,
gas and gas-liquid chromatography) require sophisticated equipment, significant duration of the analysis and extraction of soil samples, the measurement error can reach 40-50%.
2 Materials and methods
Diagnosis and ongoing monitoring of soil condition, properties and physico-chemical pro-cesses in the area of electrical treatment can be provided by geophysical methods that are effective supplement to geotechnical investigations. Very promising for the study of con-taminated soils are electrical and electromagnetic methods [10] based on the measurement of electric fields, because oil and petroleum products exhibit pronounced dielectric proper-ties and therefore they are electrically contrasting.
To control the degree of soil pollution with oil products, it is advisable to use the de-pendence of electrical resistivity of the three-phase medium on porosity, moisture and elec-trical resistivity of the pore filler that is used in elecelec-trical prospecting and includes structur-al-textural empirical parameters [11, 12]:
��= �� � ��� ���� �в (1) where m is porosity (pore cavitation); W – coefficient of the saturation space of the pores and cracks; ρв – electrical resistivity of the solution, filling pore space, Ohm⋅m; Кn, α, β, γ -
are empirical parameters that depend on the structural and textural features of the studied soils; Кn – is the parameter that takes into account the surface conductivity of clay
micro-layer on the surface of the pores; α – is the parameter depending on the type of geological deposits; β is the parameter determined by the structure of the pore space (mainly by tortu-osity of the channels); γ – parameter that depends on the wettability of surface pores by the solution.
The ranges of variation of the parameters of the pore space structure β = 1.3-2.2 and wettability γ = 1.8-3.3 should be taken for conditions of Kuzbass on the results of the in-verse calculations based on experimental data; and electrical resistivity of the pore filler is calculated by the formula of harmonic weighted average for the two-component media [13]:
��= � ��� ����= �
���
�э� �э��� �н� �н��, (2) where ρв, ρн, ρэ – electrical resistivity of, respectively, weighted, oil and electrolyte,
Ohm⋅m; Vн ,Vэ – volume fraction in the solution, respectively of the oil and electrolyte.
Theoretical dependence (1) and (2) basically allow us to assess the degree of soil pollu-tion with oil products according to the results of single measurements, longitudinal and areal electrical sounding [14].
To further analyze the process of electrochemical treatment of contaminated soils, it is necessary to have information about the electrophysical properties of natural aqueous solu-tions and liquids containing contaminants or saturated soils. Experimental studies of elec-trical properties of electrolyte solutions, containing oil-products, with the measurements at permanent and variable electric current.
Figure 1 shows the measurement results of the electrical resistivity ρэ of the NaCl
solu-tion depending on the salt concentrasolu-tion in solusolu-tion and the a. c. frequency, and Figure 2 shows the same dependence of the specific electrical resistance ρн of motor oil and
gaso-line. It follows from these data that all petroleum products are electrically quite contrasting, because their electrical resistivity is by at least 3 orders of magnitude higher than electrical resistivity of natural water solutions.
Fig. 1. The dep solution: 1 – c
Fig. 2. The dep the alternating (spent); 4 - Sh By substi the average v 3) and AC (F
Fig. 3. The dep when measure g/l; 4 - 10 g/l. The given of experimen value [15]. pendence of the constant current pendence of the g current:1 - G-E hell Helix Ultra;
itution into eq values of ρв o Fig. 4) current pendence of the ed at DC curren n dependence ntal sounding e electrical resi t; 2 - alternating e electrical resi Energy F Synth ; 5 - gasoline A quation (2) the on the relative ts. e average value nt: 1 - the salt co es allowed us when monito stivity of soluti g current, f=10 H stivity ρн of mo h 0W-40; 2 - Mo AI-92. e data of Figu e content of pe es of ρв on the re oncentration in to form the d oring the chan
ion ρэ on the sal Hz; 3 – 200 Hz
otor oil and gaso obil Synt S 5W ure 1 and Figu
etroleum prod
relative content the solution С = database for in nges in the rel
lt concentration z; 4 - 1000 Hz.
oline on the fre W-40; 3 - Shell H
gas and gas-liquid chromatography) require sophisticated equipment, significant duration of the analysis and extraction of soil samples, the measurement error can reach 40-50%.
2 Materials and methods
Diagnosis and ongoing monitoring of soil condition, properties and physico-chemical pro-cesses in the area of electrical treatment can be provided by geophysical methods that are effective supplement to geotechnical investigations. Very promising for the study of con-taminated soils are electrical and electromagnetic methods [10] based on the measurement of electric fields, because oil and petroleum products exhibit pronounced dielectric proper-ties and therefore they are electrically contrasting.
To control the degree of soil pollution with oil products, it is advisable to use the de-pendence of electrical resistivity of the three-phase medium on porosity, moisture and elec-trical resistivity of the pore filler that is used in elecelec-trical prospecting and includes structur-al-textural empirical parameters [11, 12]:
��= �� � ��� ���� �в (1) where m is porosity (pore cavitation); W – coefficient of the saturation space of the pores and cracks; ρв – electrical resistivity of the solution, filling pore space, Ohm⋅m; Кn, α, β, γ -
are empirical parameters that depend on the structural and textural features of the studied soils; Кn – is the parameter that takes into account the surface conductivity of clay
micro-layer on the surface of the pores; α – is the parameter depending on the type of geological deposits; β is the parameter determined by the structure of the pore space (mainly by tortu-osity of the channels); γ – parameter that depends on the wettability of surface pores by the solution.
The ranges of variation of the parameters of the pore space structure β = 1.3-2.2 and wettability γ = 1.8-3.3 should be taken for conditions of Kuzbass on the results of the in-verse calculations based on experimental data; and electrical resistivity of the pore filler is calculated by the formula of harmonic weighted average for the two-component media [13]:
��= � ��� ����= �
���
�э� �э��� �н� �н��, (2) where ρв, ρн, ρэ – electrical resistivity of, respectively, weighted, oil and electrolyte,
Ohm⋅m; Vн ,Vэ – volume fraction in the solution, respectively of the oil and electrolyte.
Theoretical dependence (1) and (2) basically allow us to assess the degree of soil pollu-tion with oil products according to the results of single measurements, longitudinal and areal electrical sounding [14].
To further analyze the process of electrochemical treatment of contaminated soils, it is necessary to have information about the electrophysical properties of natural aqueous solu-tions and liquids containing contaminants or saturated soils. Experimental studies of elec-trical properties of electrolyte solutions, containing oil-products, with the measurements at permanent and variable electric current.
Figure 1 shows the measurement results of the electrical resistivity ρэ of the NaCl
solu-tion depending on the salt concentrasolu-tion in solusolu-tion and the a. c. frequency, and Figure 2 shows the same dependence of the specific electrical resistance ρн of motor oil and
gaso-line. It follows from these data that all petroleum products are electrically quite contrasting, because their electrical resistivity is by at least 3 orders of magnitude higher than electrical resistivity of natural water solutions.
Fig. 1. The dep solution: 1 – c
Fig. 2. The dep the alternating (spent); 4 - Sh By substi the average v 3) and AC (F
Fig. 3. The dep when measure g/l; 4 - 10 g/l. The given of experimen value [15]. pendence of the constant current pendence of the g current:1 - G-E hell Helix Ultra;
itution into eq values of ρв o Fig. 4) current pendence of the ed at DC curren n dependence ntal sounding e electrical resi t; 2 - alternating e electrical resi Energy F Synth ; 5 - gasoline A quation (2) the on the relative ts. e average value nt: 1 - the salt co es allowed us when monito stivity of soluti g current, f=10 H stivity ρн of mo h 0W-40; 2 - Mo AI-92. e data of Figu e content of pe es of ρв on the re oncentration in to form the d oring the chan
ion ρэ on the sal Hz; 3 – 200 Hz
otor oil and gaso obil Synt S 5W ure 1 and Figu
etroleum prod
relative content the solution С = database for in nges in the rel
lt concentration z; 4 - 1000 Hz.
oline on the fre W-40; 3 - Shell H
To quant tion k is intro to the total v ble to obtain where �н – th Fig. 4. The de quency and co 3 - 1000 Hz The theor products acco ings using cy software prod
3 Results
To control th it is recomm open facilitie from the eart the treated a the electrode shown in Figify the degree oduced that is volume of the the following �н= he volume frac ependence of th oncentration of retical depend ording on the yclic algorith duct Lazarus
s and disc
he processes o mended to usees and for clo th's surface, s area boundarie es-injectors a g.5. e of saturation s equal to the r pore fluid. By g expression: �н���∙��∙�э �∙��∙� �н� �э ction of the po he average valu salt in the elect dence (3) allow results of sing ms that are im (environment
cussion
of cleaning so two schemes sed facilities. tandard metal es, using elect and feeding e n by the pollu ratio of the vo y transformati э �� � � ��� ∙ �∙ ores filling wi ues of electrica trolyte С = 0.5 ws us to estim gle measurem mplemented i Free Pascal). il of oil pollu s of sounding When using l feeding elect trodes-injecto electrodes forutant, the coef olume of oil c ion of equatio ∙ ��∙ �э ��∙ ��, ith oil. al resistivity on g/l (a); 10 g/l ( mate the degree ments, profile a in the softwar
ution by the el g from the ear
the four-elect trodes are gro ors as measuri partially ope fficient of soil contained in th ons (1) and (2 � = � ∙ �н n the alternating b): 1 - f= 10 Hz e of soil pollu and areal elect
re package cr
ectrophysical rth's surface: trode method ounded in the ing ones. The en and closed l contamina-he soil pores ) it is (3) g current fre-z; 2 - 200 Hfre-z;
tion with oil trical sound-reated in the parameters, for partially of sounding soil beyond e location of d objects is Fig.5. Circuit objects: 1 – po tion equipmen The contr tivity ρк alon sumption or t The main termination o before and af For Expr design depen studies: linea for a known contaminant the contamin tive resistivit Fig.6. Graph o in the process treated with oi ed with solven Table 1. The d
that control the ollution zone; 2 nt; 5 – area of co
rol results are ng the main a time (Fig.6). n purpose of m of electrical tr fter treatment. ess forecast o ndences obtain ar, logarithmic initial contam to volume of nation factor k ty. of changes in tim s of experimen
il; 3 – array con nt, 5 - array con dependence of ity of e processes of e 2 – feeding elect ontamination; 6 used to plot t axis of the ele monitoring is reatment, as w
.
of the numeric ned in the pro c, parabolic an mination factor f contaminated k was found at me t of the rela ntal electrical tr ntaminated with ntaminated with the contaminati f the soil in the
electrical treatm trodes A, B; 3 – 6 – structure the graphs of ectrical treatm to identify po well as the calc cal values of t cessing of the nd exponentia r kо = 7 % tha d soil. Accord t each point in ative effective e reatment: 1 – c h gasoline; 4 -h gasoline and tr ion factor k on t treatment area
ment for partial – electric powe change in the ment and depe oints of correc culation of the the contamina e data received al. The constan at is equal to t ding to the equ n time of the m
electrical resista clean clay mas array contamin reated with solv the relative cha (experimental d ly opened (a) a r unit; 4 – elect e effective elec ending on the ction of the m e coefficients ation factor, th d from experi nts а1-а4 were the ratio of th uations given measurement ance ρк at electr ssif; 2 – contam nated with used
vent
resistiv-To quant tion k is intro to the total v ble to obtain where �н – th Fig. 4. The de quency and co 3 - 1000 Hz The theor products acco ings using cy software prod
3 Results
To control th it is recomm open facilitie from the eart the treated a the electrode shown in Figify the degree oduced that is volume of the the following �н= he volume frac ependence of th oncentration of retical depend ording on the yclic algorith duct Lazarus
s and disc
he processes o mended to usees and for clo th's surface, s area boundarie es-injectors a g.5. e of saturation s equal to the r pore fluid. By g expression: �н���∙��∙�э �∙��∙� �н� �э ction of the po he average valu salt in the elect dence (3) allow results of sing ms that are im (environment
cussion
of cleaning so two schemes sed facilities. tandard metal es, using elect and feeding e n by the pollu ratio of the vo y transformati э �� � � ��� ∙ �∙ ores filling wi ues of electrica trolyte С = 0.5 ws us to estim gle measurem mplemented i Free Pascal). il of oil pollu s of sounding When using l feeding elect trodes-injecto electrodes forutant, the coef olume of oil c ion of equatio ∙ ��∙ �э ��∙ ��, ith oil. al resistivity on g/l (a); 10 g/l ( mate the degree ments, profile a in the softwar
ution by the el g from the ear
the four-elect trodes are gro ors as measuri partially ope fficient of soil contained in th ons (1) and (2 � = � ∙ �н n the alternating b): 1 - f= 10 Hz e of soil pollu and areal elect re package cr
ectrophysical rth's surface: trode method ounded in the ing ones. The en and closed l contamina-he soil pores ) it is (3) g current fre-z; 2 - 200 Hfre-z;
tion with oil trical sound-reated in the parameters, for partially of sounding soil beyond e location of d objects is Fig.5. Circuit objects: 1 – po tion equipmen The contr tivity ρк alon sumption or t The main termination o before and af For Expr design depen studies: linea for a known contaminant the contamin tive resistivit Fig.6. Graph o in the process treated with oi ed with solven Table 1. The d
that control the ollution zone; 2 nt; 5 – area of co
rol results are ng the main a time (Fig.6). n purpose of m of electrical tr fter treatment. ess forecast o ndences obtain ar, logarithmic initial contam to volume of nation factor k ty. of changes in tim s of experimen
il; 3 – array con nt, 5 - array con dependence of ity of e processes of e 2 – feeding elect ontamination; 6 used to plot t axis of the ele monitoring is reatment, as w
.
of the numeric ned in the pro c, parabolic an mination factor f contaminated k was found at me t of the rela ntal electrical tr ntaminated with ntaminated with the contaminati f the soil in the
electrical treatm trodes A, B; 3 – 6 – structure the graphs of ectrical treatm to identify po well as the calc cal values of t cessing of the nd exponentia r kо = 7 % tha d soil. Accord t each point in ative effective e reatment: 1 – c h gasoline; 4 -h gasoline and tr ion factor k on t treatment area
ment for partial – electric powe change in the ment and depe oints of correc culation of the the contamina e data received al. The constan at is equal to t ding to the equ n time of the m
electrical resista clean clay mas array contamin reated with solv the relative cha (experimental d ly opened (a) a r unit; 4 – elect e effective elec ending on the ction of the m e coefficients ation factor, th d from experi nts а1-а4 were the ratio of th uations given measurement ance ρк at electr ssif; 2 – contam nated with used
vent
resistiv-Equatio � � ��∙ � � � ��∙ ln � � ��∙ (�� � � ��∙ ��� Fig.7 pre The graph sh and then stab terion for the not give any
Fig.7. Graphs depending on – exponential
4 Conclu
The depende porosity, mo formula of th of control of tions of Kuzb bility are, re lished ranges major types bases were c ratio of the v Express-c ment of the s the scheme w measuring on when contam line – to 3.49 on The �к �к� a1 (�к��к) a2= �к �к�)� a3= �(�к��к) a4=sents the chan hows that the bilizes. The tim e termination significant po of change in co time t: 1 – linea dependence.
sions
ence of electric oisture and ele he harmonic w f the degree obass the range spectively, β s of change o of petroleum calculated for volumetric pro control of cha soil is ensured with the zone nes. During t minated with u 9 % (exponent value of the co at pollution oil g 1=2.8 =7.64 a =1.12 a =0.575 a
nge in the coe coefficient o me of stabiliz of electrical ositive effect. oncentrations o ar dependence; cal resistivity ectrical resist weighted aver f pollution of es of change i = 1.3-2,2 and f the resistivi products (fue dependences oportion of oil anges in conta d according to e-by-zone int the experimen used oil declin tial dependenc onstant а n in gasoline a1=3.5 a2=10.1 a3=1.75 a4=0.95 fficient of pol f pollution kз ation of the ca treatment as a
f waste oil (a) a 2 – logarithmic
(electrical res ivity of the p rage is the phy f soils with pe
in structural p d γ = 1.8-3.3. ty of an aque el, engine oil) of the effectiv
and moisture amination fac o the value of t
egral soundin ntal trials afte ned from 7 to ce). T nitial k0, % 7 llution kз (con with time de alculated valu any further ex and gasoline (b) c dependence; 3 sistivity) of th pore filler, ca ysical basis of etroleum prod parameters of On the basis eous solution ) (ρн = (0.2-1 ve specific ele e in the range o ctor k in the p the effective e ng using as e er treatment f 2.11 %, and The value k final kк, % oil gaso 3.64 2 1.9 2.11 ncentration of creases until ue of k is an o xposure of the ) during electric 3 – parabolic de he three-phase lculated acco f electrophysi ducts, while fo the pore space s of experimen (ρв = 0.2-80 O .1).106 Ohm.m ectric resistivi of Vн/Vв = 0-2 process of elec electrical resis lectrodes-inje for 168 h, the when polluted oline 4.55 2.65 2.96 3.49 oil) in time. t = 48-72 h, bjective cri-e array docri-es cal treatment ependence; 4 e medium on rding to the cal methods or the condi-e and wcondi-etta- wetta-ntally estab-Ohm.m) and m), the data-ity ρк on the 20. ctrical treat-stivity ρк for ctors as the e value of k d with
gaso-Stabilization of the k value at a minimum level is a criterion for the transition to a more intensive mode of electrical treatment or, if the capacities of the power electric unit are ex-hausted – this is a sign that further treatment makes no sense.
References
1. V. P. Seredina, M. E. Sadykov, Contemporary Problems of Ecology, 5, 457 (2011)
2. V. A. Efremova, E. V. Dabakh, L. V. Kondakova, Contemporary Problems of Ecolo-gy, 5, 561 (2013)
3. S. I. Kolesnikov, M. G. Zharkova, K. Sh. Kazeev, Russian Journal of Ecology, 3, 157
(2014)
4. T. I. Kukharchyk, V. S. Khomich, Eurasian soil science, 2, 145 (2013)
5. V. A. Korolev, A. M. Romanyukha, O .V. Abyzova, Journal of Environmental Sci-ence and Health, 43:8, 876 (2008)
6. I. Gratchev, I. Towhata, Soils and foundations, 3, 469 (2013)
7. C.J. Tsai, C.H. Feng, J.H. LI, Journal of chromatography, 1410, 60 (2015)
8. Z. Zhou, F. Bing, W. Tao, X. Song, IEEE transactions on dielectrics and electrical insulation, 5, 1498 (2012)
9. E.Y. Kovalenko, T.A. Sagachenko, E. B. Golushkova, Petroleum chemistry, 2,101
(2016)
10. S.A. Smernikov, A.I. Pozdnyakov, E.V. Shein, Eurasian soil science, 10, 1059 (2008)
11. B. Leiss, K. Ullemeyer, K. Weber, Journal of structural geology, 11:12. 1527 (2000)
12. S. M. Prostov, V. A. Khyamyalyainen, S. P. Bakhaeva Journal of Mining Science, 4,
349 (2006)
13. G.G. Shtumpf, Journal of Mining Science, 6, 59 (1993)
14. S. M. Prostov, E. A. Shabanov, Proceedings of the 8th Russian-Chinese Symposium “Coal in the 21st Century: Mining, Processing, Safety". Advances in Engineering Re-search, 175 (2016).
Equatio � � ��∙ � � � ��∙ ln � � ��∙ (�� � � ��∙ ��� Fig.7 pre The graph sh and then stab terion for the not give any
Fig.7. Graphs depending on – exponential
4 Conclu
The depende porosity, mo formula of th of control of tions of Kuzb bility are, re lished ranges major types bases were c ratio of the v Express-c ment of the s the scheme w measuring on when contam line – to 3.49 on The �к �к� a1 (�к��к) a2= �к �к�)� a3= �(�к��к) a4=sents the chan hows that the bilizes. The tim
e termination significant po of change in co time t: 1 – linea dependence.
sions
ence of electric oisture and ele he harmonic w f the degree obass the range spectively, β s of change o of petroleum calculated for volumetric pro control of cha soil is ensured with the zone nes. During t minated with u 9 % (exponent value of the co at pollution oil g 1=2.8 =7.64 a =1.12 a =0.575 a
nge in the coe coefficient o me of stabiliz of electrical ositive effect. oncentrations o ar dependence; cal resistivity ectrical resist weighted aver f pollution of es of change i = 1.3-2,2 and f the resistivi products (fue dependences oportion of oil anges in conta d according to e-by-zone int the experimen used oil declin tial dependenc onstant а n in gasoline a1=3.5 a2=10.1 a3=1.75 a4=0.95 fficient of pol f pollution kз ation of the ca treatment as a
f waste oil (a) a 2 – logarithmic
(electrical res ivity of the p rage is the phy f soils with pe
in structural p d γ = 1.8-3.3. ty of an aque el, engine oil) of the effectiv
and moisture amination fac o the value of t
egral soundin ntal trials afte ned from 7 to ce). T nitial k0, % 7 llution kз (con with time de alculated valu any further ex and gasoline (b) c dependence; 3 sistivity) of th pore filler, ca ysical basis of etroleum prod parameters of On the basis eous solution ) (ρн = (0.2-1 ve specific ele e in the range o ctor k in the p the effective e ng using as e er treatment f 2.11 %, and The value k final kк, % oil gaso 3.64 2 1.9 2.11 ncentration of creases until ue of k is an o xposure of the ) during electric 3 – parabolic de he three-phase lculated acco f electrophysi ducts, while fo the pore space s of experimen (ρв = 0.2-80 O .1).106 Ohm.m ectric resistivi of Vн/Vв = 0-2 process of elec electrical resis lectrodes-inje for 168 h, the when polluted oline 4.55 2.65 2.96 3.49 oil) in time. t = 48-72 h, bjective cri-e array docri-es cal treatment ependence; 4 e medium on rding to the cal methods or the condi-e and wcondi-etta- wetta-ntally estab-Ohm.m) and m), the data-ity ρк on the 20. ctrical treat-stivity ρк for ctors as the e value of k d with
gaso-Stabilization of the k value at a minimum level is a criterion for the transition to a more intensive mode of electrical treatment or, if the capacities of the power electric unit are ex-hausted – this is a sign that further treatment makes no sense.
References
1. V. P. Seredina, M. E. Sadykov, Contemporary Problems of Ecology, 5, 457 (2011)
2. V. A. Efremova, E. V. Dabakh, L. V. Kondakova, Contemporary Problems of Ecolo-gy, 5, 561 (2013)
3. S. I. Kolesnikov, M. G. Zharkova, K. Sh. Kazeev, Russian Journal of Ecology, 3, 157
(2014)
4. T. I. Kukharchyk, V. S. Khomich, Eurasian soil science, 2, 145 (2013)
5. V. A. Korolev, A. M. Romanyukha, O .V. Abyzova, Journal of Environmental Sci-ence and Health, 43:8, 876 (2008)
6. I. Gratchev, I. Towhata, Soils and foundations, 3, 469 (2013)
7. C.J. Tsai, C.H. Feng, J.H. LI, Journal of chromatography, 1410, 60 (2015)
8. Z. Zhou, F. Bing, W. Tao, X. Song, IEEE transactions on dielectrics and electrical insulation, 5, 1498 (2012)
9. E.Y. Kovalenko, T.A. Sagachenko, E. B. Golushkova, Petroleum chemistry, 2,101
(2016)
10. S.A. Smernikov, A.I. Pozdnyakov, E.V. Shein, Eurasian soil science, 10, 1059 (2008)
11. B. Leiss, K. Ullemeyer, K. Weber, Journal of structural geology, 11:12. 1527 (2000)
12. S. M. Prostov, V. A. Khyamyalyainen, S. P. Bakhaeva Journal of Mining Science, 4,
349 (2006)
13. G.G. Shtumpf, Journal of Mining Science, 6, 59 (1993)
14. S. M. Prostov, E. A. Shabanov, Proceedings of the 8th Russian-Chinese Symposium “Coal in the 21st Century: Mining, Processing, Safety". Advances in Engineering Re-search, 175 (2016).
