Residues of Persistent Organic Pollutants (POPs) in Agricultural Soils Adjacent to Historical Sources of Their Storage and Distribution—The Case Study of Azerbaijan

Abstract

The aim of this study was to identify and examine the levels of organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) in soil collected from the surroundings of historical pesticide storage facilities on former agricultural aerodromes, warehouses, and pesticide distribution sites located in the most important agricultural regions in Azerbaijan. The conducted research included determination of three groups of POPs (occurring together), in the natural soil environment influenced for many years by abiotic and biotic factors that could have caused their transformations or decomposition. In this study, soil samples were collected in 21 georeferenced points located in the administrative area of Bilasuvar, Saatly, Sabirabad, Salyan and Jalilabad districts of Azerbaijan. Soil chemical analysis involved determination of organochlorine compounds (OCP): hexachlorocyclohexanes (HCHs) (three isomers α-HCH, β-HCH and γ-HCH) and dichlorodiphenyltrichloroethanes (DDTs) (six congeners 2,4 DDT; 4,4 DDT; 2,4 DDE; 4,4 DDE; 2,4 DDE; and 4,4 DDE); polycyclic aromatic hydrocarbons (PAHs): 16 compounds from the United States Environmental Protection Agency US EPA list and, PCBs (seven congeners identified with the following IUPAC numbers: 28, 52, 101, 118, 138, 153, and 180). Our research showed that OCPs reached the highest concentration in the studied areas. The total concentrations of OCPs ranged from 0.01 to 21,888 mg·kg −1 with significantly higher concentrations of Σ6DDTs (0.01 µg kg −1 to 21880 mg kg −1 ) compared to ΣHCH (0.14 ng kg −1 to 166.72 µg kg −1 ). The total concentrations of PCBs in the studied soils was varied from 0.02 to 147.30 µg·kg −1 but only PCB138 and PCB180 were detected in all analyzed samples. The concentrations of Σ16 PAHs were also strongly diversified throughout the sampling areas and ranged from 0.15 to 16,026 mg kg −1 . The obtained results confirmed that the agricultural soils of Azerbaijan contained much lower (up to by three orders of magnitude) concentrations of PCBs and PAHs than DDT. It is supported by the fact that PCBs and PAHs were not directly used by agriculture sector and their content results from secondary sources, such as combustion and various industrial processes. Moreover, the high concentrations of PAHs in studied soils were associated with their location in direct neighborhood of the airport, as well as with accumulation of contaminants from dispersed sources and long range transport. The high concentrations of pesticides confirm that deposition of parent OCPs have occurred from obsolete pesticide landfills.

The Impact of Organic Matter on Polycyclic Aromatic Hydrocarbon (PAH) Availability and Persistence in Soils

“…All of them can be derived from both petrogenic and pyrogenic sources and therefore may be representative compounds for the PAH group. The analytical procedure for TE-PAHs was fully described by Maliszewska-Kordybach et al [1,2] and Ukalska-Jaruga et al [8,24]. The analytical steps included extraction of ground soil samples (grain size ≤ 0.10 mm) with dichloromethane in an ASE200 Accelerated Solvent Extractor (Dionex Co., Sunnyvale, CA, USA).…”

“…Polycyclic aromatic hydrocarbons (PAHs) are contaminants of global concern, and in soils they can be found at high concentrations, indicating a potential environmental hazard. PAHs mainly originate from the long-term deposition of airborne particles emitted from natural (e.g., volcanic eruptions, forest fires) and anthropogenic (e.g., industry, traffic, road runoff) sources [1][2][3][4][5][6][7][8]. These contaminants are susceptible to global long-range transport; therefore, they can be detected in soils even at long distances from their emission sources [9].…”

Validation of a Method Scope Extension for the Analysis of POPs in Soil and Verification in Organic and Conventional Farms of the Canary Islands

“…In fact, p,p’-DDE levels in the samples of our series presented mean (364.6 ± 698.7 ng g −1 ) and median (58.7 ng g −1 ) values that are much higher than those reported in other recent studies in Turkey [ 65 ], India [ 66 ], Poland [ 67 , 68 ], or Iran [ 69 ]. In fact, the highest value in our series (2305.6 ng g −1 ), which paradoxically was found in a farm dedicated to organic vegetable farming, was about twice the median value reported for a region of Azerbaijan that has been reported to be historically contaminated by DDT (and its metabolites), because it was subjected to intensive aerial spraying campaigns [ 70 ]. It is still surprising that more than 50 years after the banning of DDT, such high levels of its metabolites are still detected.…”

Polycyclic Aromatic Hydrocarbons in Soil at Different Depths under a Long-Term Experiment Depending on Fertilization

“…It was found that the main sources of PAHs came from the coal and wood combustion. The origin of PAHs in the soil is connected to the decomposition of airborne particles that were emitted from natural as well as anthropogenic sources [ 36 , 37 ].…”