Characterizations of PAHs in sediments/soil for source identification and .. Developed a linear correlation between the “time since release in years” and. Abstract: The distribution and sources of PAHs in sediments as well as TPH were investigated in .. Moreover, the negative correlation between abundance and. Total Petroleum and Total Recoverable Hydrocarbons (TPH and TRH) PAH also known as polycyclic aromatic hydrocarbons or polynuclear aromatic.
Another compound n-hexane can affect the central nervous system in a different way, causing a nerve disorder called "peripheral neuropathy" or may negatively affect the blood, immune system, liver, spleen, kidneys, developing foetus, and lungs.
Certain petroleum compounds can be irritating to the skin and eyes. The International Agency for Research on Cancer IARC has determined that benzene is carcinogenic to humans Group 1 classification and may cause leukaemia while benzo a pyrene and gasoline are considered to be probably and possibly carcinogenic to humans [ 6 ].
Therefore this study was aimed at investigating the levels of selected pollutants in food sources from this polluted swamp and to assess level of danger the people are exposed to as a result of the consumption of products from oil polluted swamps. The study area is a seasonal swamp and a flood plain of the Sombreiro-Orashi inter-basinal system.
This type of fishing activity is very common among local people in the Niger Delta area. The Niger Delta Swamp Forests ecoregion is contained in a triangle with the town of Aboh on the Niger River being the northernmost tip. The Benin River forms the western boundary of the ecoregion where this ecoregion merges into the Nigerian Lowland Forest ecoregion. The Imo River forms the eastern side where this ecoregion merges into the practically vanished Cross-Niger Transition Forests ecoregion.
Along its southern side the Niger Delta Swamp Forests is separated from the Atlantic Ocean by a band of mangroves, which can reach up to 10 kilometers km inland. In front of the mangrove belt and close to the sea are ephemeral coastal barrier islands often clothed in transitional vegetation [ 7 ].
Assessment of soil pollution based on total petroleum hydrocarbons and individual oil substances.
The Mgbede fresh water swamps are part of the Niger Delta flood forest. This zone shows strong seasonal variation. During the dry season the soil is dry save for the seasonal flood channels, a few permanent creeks, and some lakes. During the rainy season water levels slowly rise, eventually leading to complete inundation during the Niger River flood, which lasts generally from October through December [ 7 ].
The climate of the study area is characterized by a long rainy season from March-April through October which is characteristic of the Tropical rainforest climate marked by very high rainfall, temperature and relative humidity. Materials and Methods The impacted ponds were purposefully selected for this study. Surface water and biota Water Lettuce- Pistia stratiotes ; water snail- Pila Ovata and cray fish- Epiplatys fasciolatus-Banded Epiplatys were sampled and analysed for physico-chemical parameters, heavy metals and PAH.
Data collection Several methods of data collection were employed in this study. They include water and biota sampling, field and laboratory analysis, global position GPS measurements and on-the-spot interview.
Water sampling and analysis Polycyclic aromatic hydrocarbons PAHsheavy metals Ni, Mn, Zn, Pb, and Cd and Physico-chemical characteristics of water in the ponds including pH, temperature, oxidation-reduction potential ORPdissolved oxygen DObiological oxygen demand BODalkalinity, sulphate, electrical conductivity, turbidity, salinity, chloride, phosphate, nitrate, sulphate, calcium, magnesium and water hardness were measured with field devices and laboratory methods using standard procedures [ 8 - 10 ].
Two samples of water were taken at each sampling point for physico-chemical and metals analysis following the methods described in Ezekwe et al. Metals were analysed by atomic absorption AA spectrophotometry using a Perkin-Elmer and Analyst AA spectrophotometer detection limit 0.
All manipulations were done under controlled conditions and in duplicate to avoid contamination. Measurements of pH, temperature, EC, turbidity, and salinity were done in situ, using a Horiba water checker model U after calibrating the instrument with the standard Horiba solution. Total dissolved solids TDS were measured with a Lovibond cm Tintometer, while total alkalinity, hardness, Ca, and Cl- were determined by titration.
Phosphate, nitrate, and sulphate were determined using the stannous chloride, brucine, and turbidimetric methods, respectively, while Mg concentration was determined by calculation [ 8 ]. Samples for hydrocarbon analysis were collected in ml glass bottles and preserved by adding 1ml HCl analytical grade.
After complete phase separation the lower organic phase was removed for absorbance determination and total hydrocarbon content determined spectrophotometrically at nm wave length using HACH DR [ 12 ]. Biota sampling and analysis Samples of macerated biota tissues were digested and extracts evaluated for selected heavy metal and PAH contents. Before analysis, two grams 2g of ground oven dried total body weight were weighed using a high precision microscale and put in a digestion flask and digested with a mixture of 10ml of concentrated nitric acid and 2ml of concentrated perchloric acid.
The contents of the flask was, for each case, digested gently and slowly, by heating in a water bath until the contents got to near dryness. It was then set aside to cool. The digest was filtered into a 50ml volumetric flask, made up to mark with distilled water and the concentrations of selected metals were determined by atomic absorption spectrophotometry using the Buck Scientific Model a Spectrophotometer, equipped with a high sensitivity nebulizer.
Polycyclic Aromatic Hydrocarbons were extracted from macerated biota tissues and shells after digesting with potassium hydroxide and the digest extracted with 1,1,2-trichlorotrifluoroethane TCTFE. The extracts were further purified to avoid interferences by aliphatic hydrocarbons, porphrins, chlorins, and carotenoids using I alumina as an adsorbent. Concentrated extracts were then dissolved in hexane and subsequently introduced to the wet adsorbent and eluted with hexane to remove aliphatic hydrocarbons.
A second eluant was benzene, which removed the aromatic components with sufficient purity for the Capillary Gas Chromatographic analysis. The column used was a HP-5, 30 m X 0. Table 2 shows that of all the contaminants analysed in the biota samples from the study area only zinc were within safe limits for the protection of health.
Nickel concentration ranged between 2. Chromium concentrations were above same standards in water lettuce, fish and snail shell.
Highest concentration of Discussion Environmental proxies According to Aboho et al. The snail can accumulate higher concentrations of metal ions than any other group of invertebrates especially in aquatic systems. These snails constitute an important source of diet, while their shells are applied in traditional medicine.
The Pila ovata has also been used severally and successfully in environmental monitoring studies [ 18 - 21 ]. The water lettuce Pistia stratiotes is another unique proxy for this investigation. It is a free-floating waterweed found mostly in tropical waters. Under favourable conditions, it forms dense mats over the surface of slow-moving waterways, including dams and reservoirs.
Sharma [ 22 ] stated that water lettuce is one of the dominant aquatic weeds in fresh waters, polluted lakes and streams of Nigeria. It shows much higher metal-accumulating capacity than non-hyper accumulating terrestrial plants [ 23 ]. It also has medicinal properties and is used for traditional medicine and fodder in the study area [ 24 ].
The fish of the genus Epiplatys are native to Africa and are found in small watercourses and pools with sandy bottoms and live almost exclusively at or near the surface of the water. Their behaviour can be described as generally motionless, pike-like, with occasional abrupt lunges at prey.
Several national policies include the IV based on the so called total 22 August petroleum hydrocarbons TPH measure. However, the TPH assessment does not indicate the individual Accepted 22 August Available online substances that may produce contamination.
The soil quality assessment can be improved by including common hazardous compounds as polycyclic aromatic hydrocarbons PAHs and aromatic volatile hy- drocarbons like benzene, toluene, ethylbenzene and xylenes BTEX. This study, focused on 62 samples Keywords: On the other hand, unacceptable BTEX concentrations are reached in soils contaminated with gasoline and kerosene.
The TPH assessment suggests the need for further action to include lighter products. The application of multivariable indices allows us to include these products in the soil quality assessment without changing the IV for TPH. This work provides useful information about the soil quality assessment methodology of oil products in soils, focussing the analysis into the sub- stances that mainly cause the risk.
The volume of crude oil and petroleum prod- carbons PAH and volatile aromatic hydrocarbons: Petroleum products including A proper risk assessment is essential for the understanding and gasoline, diesel or lubricants can be released to the environment management of the soil polluted by hydrocarbons, enabling us to through accidents, managed spills, or as unintended by-products of develop a suitable risk assessment framework Karlen et al.
Petroleum mixtures can et al. TPH concentration is a global parameter including be affected by air, water and organisms, thereby changing the many derived petroleum products, commonly applied to establish location and their composition in soil, water or air Doran and Zeiss, target soil cleanup levels implemented by several regulatory The IVs measured value with the maximum limit values established in for these substances are based on the adverse effects of these national regulations Pinedo et al.
In the case of clean Thus, it is expected that the inclusion of PAH and BTEX concen- soil, no further action is necessary since the risk is acceptable for trations will improve the soil quality assessment since they com- human health and the environment. When the soil is slightly plement TPH analysis and include potential risks.
In this case, monitoring campaigns effects Weisman, However, some carcinogenic substances must be performed to track the contaminants concentration. In the can be found in oil products.
PAH and BTEX are both composed of case of unacceptable high concentration of pollutants, the soil can carcinogenic and toxic substances, providing more reliable results. Taking SQS divides soils between clean and slightly contaminated soils the Dutch regulation as regulative reference, PAH are evaluated by Swartjes et al. The second SQS establishes differences between slightly does not include the most volatile compounds found in petroleum and seriously contaminated soils.
BTEX are very volatile compounds which are commonly as a generic value, like in The Netherlands with the intervention detected in oil spills.
As an example, in France, some generic soil concen- The inclusion of PAH and BTEX variables offers multiple trations are established, although they cannot be used as soil risk assessment options for the same site under study.
In Germany, a few sub- based on the concentration of individual substances without the stances present regulation values, the different soil levels are risk- necessity to perform a TPH-fractionation assessment.
Hereinafter, the SQS names that are adopted in this work different oil substances: Besides, a comparative study VROM, Sixty-two samples and toxicological properties of the individual compounds throughout The Netherlands have been selected as a case of study.
Managing Different origins for soil contamination are considered, from the ecological and human health risks requires the understanding of lighter and more volatile oil products to the heavier ones: The application of the risk assess- ; Verbruggen et al. Some analytical methods to iden- ment criteria for the substances under study will allow us to tify and quantify TPH as hydrocarbon fractions have been devel- determine the soil quality through a comparison between the oped.
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Petroleum hydrocarbon fraction methods break the TPH measured values and the IV, supporting the decision-makers in the mixture into discrete hydrocarbon fractions MassDEP, ; environmental risk management. Some studies have been conducted in the same line adapting the fraction ranges Park and Park, ; 2. Methodology Pinedo et al. This provided data can be used in a site- The methodology of this study is depicted in Fig.
Site management framework and the actions to be carried out depending on the among contaminants depending on the origin of the substances. YES Additional risks Fig. Methodology applied in this study to carry out the risk assessment due to petroleum products.
The dataset is provided by TTE consultancy from the analysis The number of available concentration data is variable since not performed by Alcontrol Laboratories, considering a total of 62 all the compounds were found in the 62 samples under study. The dataset is divided over different oil Table 1 shows the average concentrations of the individual com- products, distinguishing also between fresh and weathered spills.
From this The oil products included in the study comprise a great range of dataset, the origin of the highest TPH and PAH concentrations petroleum hydrocarbons, from the lighter ones such as gasoline found in soils is heavy oil.
The contaminants which gasoline and kerosene. Finally, IBTEX includes As an initial step, an individual criterion for each variable is seriously contaminated sites due to oil products with lower mo- applied to the soil quality assessment. Considering the concentra- lecular weight. Multivariable assessment individual compound: In total, six individual risk assessment criteria are agement.
An individual index B, T, E and X. The IVs applied to obtain Ii values are listed in Table 2. A multivariable index IMV is looking for any interaction among these substances.
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The study begins with the rest of IVs or otherwise, it represents a too conservative value. Secondly, PAH variables are 3. Individual criteria for intervention values Table 2 3. In addition, the dimensionless IV of 1. Regarding PAH Benzene 1. The percentages for each oil product are presented in parentheses. These results suggest a strong correlation affected by diesel and heavy oil had TPH concentrations below the between both indices.
As far as TPH origin is concerned, lighter products like gasoline and kerosene usually have concentrations below the IV, whereas 3. Only 2 of the 12 total proaches were performed for the BTEX assessment. Samples approach considered the individual addition of seriously contami- contaminated with heavy oil generally pose unacceptable concen- nated samples.
Assessment of soil pollution based on total petroleum hydrocarbons and individual oil substances.
The main differences and X are depicted in Fig. Xylenes were found in all samples between TPH and PAH seriously contaminated samples are present except one only affected by benzene. Xylenes can be found alone when soil is affected by diesel.
From 27 samples affected by this six samples or be present together with benzene three samples product, six samples exhibit TPH concentrations higher than the IV or toluene four samples. Focussing on the In Fig.