Abstract
This study examined the remediation of crude oil polluted soils obtained from Ohaji Egbema Imo State Nigeria using macerated roots of T. diversifolia (TD) and S. jamaicensis (SJ). The soil pH levels, PAHs (Polycyclic aromatic hydrocarbons) and TPH (Total petroleum hydrocarbons) contents, and catalase and peroxidase activities were evaluated. Thirty-two polyethene bags containing 300g of soil samples were divided into eight groups of quadruplicates. Group 1 were the unpolluted soil samples (USS), group 2; polluted soil samples (PSS) without remediation, group 3; PSS containing 250g of TD, group 4; PSS containing 500g of TD, group 5; PSS containing 250 g of SJ, group 6; PSS containing 500g of SJ, group 7; PSS containing 250g of the mixture of TD and SJ (1:1) and group 8; PSS containing 500g of the mixture of TD and SJ (1:1). At all experimental periods, the pH of the PSS without remediation was significantly lower than the USS. The 500 g TD completely normalized the altered pH of the PSS on the 4th week, comparable to the results of the 12th week. The PAH (Polycyclic aromatic hydrocarbons) levels in the group 5 and 7 on the 1st day were not significantly different from the PAH of the group 2. Group 3, 4, 7, and 8 produced the best PAH lowering effects on the polluted soils on the 8th week, which compared to the results of the 12th week. At all experimental periods, 500g of TD provided the most effective for TPH reduction of the polluted soils. Results for the enzyme activities showed a significantly decreased (p < 0.05) catalase and peroxidase levels of the polluted soils when compared to the USS. Both the 1st day and 1st week recorded similar catalase activities in all groups except group 5, while group 4-8 recorded significantly increased catalase activities from the 4 - 12th week. For the 1st day, 1st week, and 4th week, increasing the amount of the plants from 250g - 500g had no effect on the peroxidase levels of the soils, while a quantity dependent significant increase in peroxidase levels was observed only for group 7 and 8 on the 8th and 12th weeks. The 500g TD produced the most significant restorative effect on the polluted soils. This study has shown the extensive remediation produced by TD on crude oil polluted soils of Ohaji Egbema.
Highlights
The soil is an essential part of the terrestrial ecosystem, and as well, central to production activities in agriculture [1]
Polycyclic aromatic hydrocarbons are by products that result from incomplete breakdown of petroleum products, organic materials, fossil fuels, and various industrial activities [3]
The aim of this study was to determine the effect of soil amendment on crude oil contaminated soils from Ohaji Egbema L.G.A in Imo State Nigeria, using macerated roots of Tithonia diversifolia and Strachytarpheta jamaicensis
Summary
The soil is an essential part of the terrestrial ecosystem, and as well, central to production activities in agriculture [1]. The importance of soil to human existence, especially for agriculture, cannot be overemphasized, and has been subjected to various forms of abuse, such as deposition of petroleum by products, petroleum spillage, waste disposal and other contaminants [2]. Evaluation of PAHs has recently attracted various interests as a result of their persistent, toxic and carcinogenic characteristics [5]. Rauckyte et al [6] defined Total Petroleum Hydrocarbons (TPH) as the detectable amount of petroleum based hydrocarbons in the environment, and the human toxicity of these hydrocarbons depend on their physical and chemical nature. Costello, [7] has reported various toxicities of TPH related to the circulatory, nervous, Application of Root Maceration of Common Weeds: T. diversifolia and
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