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Analyzing Spatiotemporal Variability of Constituents Present in Waters and Soils of Oil Exploitation Areas in Anzoátegui and Monagas States, Venezuela

SPATIAL VARIATION,TEMPORAL VARIATION,WATERS,SOILS,OIL EXPLOTAITION

Venezuela is a country rich in water resources, both surface and underground. To guarantee the quality and quantity of these waters over time, it is necessary to establish a continuous control system over the use of these waters, which means balancing the exploitation of the resource in terms of quantity, quality and relationship with other natural resources. The method involved a) description of the bacteriological and physicochemical characteristics of soils and surface waters of oil exploitation areas of Anzoátegui and Monagas states according to environmental regulations. Sampling period included years 2009 to 2013, this period was selected due to the great increase in anthropogenic activities carried out since 2008 as a consequence of a series of commercial agreements with different countries for oil exploitation in the Anzoátegui and Monagas states, recognizing its potential and accumulation of large oil reserves, that exists in the world, b) different types of environmental quality indexes and their application in the study area were investigated, c) analysis of the spatial and temporal variations of bacteriological and physicochemical parameters were determined through use of geographic information systems. Surface waters presented a low quality compared to the results obtained by other researchers, however, they did not reach values of domestic wastewater. This alteration was confirmed due to the ratio Biochemical Oxygen Demand (BOD)/Chemical Oxygen Demand (COD) based on the average of each parameter was equal to 0.3. Soils had pH values that remained stable throughout the study period with an average value of (5.42 ± 0.01) and (5.69 ± 0.01) for soils in areas adjacent to spills and in treatment respectively, which indicated that the pH of soils was moderately acid. These values were in correspondence with an increasing trend of concentrations of heavy metals (Ba, Cd, Cr, Pb) in the soils adjacent to the spill areas, observing an opposite trend in the soil samples under treatment. In general, Environmental Quality Indexes (EQI) evaluated reflected that both groundwater and surface water presented a deterioration in water quality, which was obtained more markedly in surface water than in groundwater, this might be due to the filtering capacity of the soil. The soils in the areas adjacent to the spills had a quality between good and excellent while the impacted soils have a regular and good quality, which was expected since the impacted soils have been affected by the anthropogenic activities carried out in these sites.