Verification of Vehicular Emitted Aerosol Components in Soil Biochemical Characteristics

Received Jul 26, 2012 Revised Oct 26, 2012 Accepted Nov 4, 2012 The study was carried out in Avu Junction in Owerri West L.G.A. at graded distant from the tarred road with an average vehicu lar flow between 10,000 to 12,000 per day. Soil samples were taken at the d istant of 50m, 100m, 150m and 200m respectively. And auger soil samples w re taken at the depths of 0-30 cm and 30-45 cm accordingly. Soil fa ctor, heavy metals and microbial populations were investigated at graded d istances. From the result of soil factors, pH values indicated acidity with decreased distant from the tarred road ranging between 4.52 – 6.32, soil tem perature on the topsoil was higher than subsoil ranging between 1925 C and 18 – 22 C and soil moisture increases with increased distant from the tarred road ranging between 10.00 – 13.3. Heavy metal concentrations in the soil increased with decreased distant in the order of Pb < Zn < Ni < Cu < Cd. Overall results revealed that Cd in the soil constitutes the high est percentage of 91.7%, Ni 90.9%, Cu 90.1%, Pb. 84.7% and Zn. 81.7%. Significa ntly, higher fungi and bacterial populations were recorded at increased di stant from the tarred road. This then called for proactive measures to checkmat e soil contamination due to pollutants from vehicular flows.  Keyword:.


INTRODUCTION
Roads form the main system of transportation of the region. Driving a car is the most air polluting act an average citizens commits. Roadside soils often show a high degree of contamination that can be attributed to motor vehicles (Weckwerth ,2001) .This is because car exhaust is toxic at ground level. Trace heavy metal contamination in the soils is a major concern because of their toxicity and the threat to human life and environment (Barbhuiya et al, 2008) .This has led to the loss of forest cover and subsequent loss of soil fertility. Heavy metals such as Cu, Cd, Ni, and Pb are potential soil and water pollutants ( Mander, 1983;Pagotto et al (2001) . Vehicular discharge of numerous gaseous and trace metals contaminants due to incomplete combustion of petroleum fuel adversely affects the microbial population and their activities in soil. Contamination of litter and soil with metals can result in reduced rates of litter decomposition, soil respiration, nitrogen mineralization and soil enzyme activity (Tyler et al, 1989). Moderate soil contamination by metals has been shown to reduce the soil microbial biomass and certain indices of its activity (Brooks et al, 1986).
The interactions of chemical, physical and biochemical factors are responsible for holding the complex soil system in a dynamic equilibrium. Population dynamics of soil microorganisms is largely regulated by vegetation and soil characteristics. Soil micro flora exerts considerable influence on soil fertility and plant growth. Biochemical processes provide better estimates of the functional attributes of the microorganisms in an ecosystem. These are generally determined by the estimation of the rate of biochemical processes involving microbial enzymes, and soil factors. Enzymes in soil are biologically significant as they are involved in cycling of nutrients and can influence the availability of nutrients to plants thus playing an important role in the initial phase of decomposition of organic matter (Joshi, 1991).Tropical and subtropical soils have received less attention in relation to microbial dynamics as affected by disturbances (Joshi et al, 1992;Barbhuiya et al, 2008).
The present study aims to understand the influence of roadside pollution caused by vehicular flow/density on population and activity of microorganisms and physicochemical properties of the soil in Owerri West Local Government Area of Imo State.

MATERIALS AND METHODS (a) Study Area
The research study is carried out in Owerri West Local Government Area of Imo State. lt is located in the southern part of the State within latitude 06 0 52' E and 07 0 05' E, longitude 05 0 , 15' N and 05 0 34' N of the South East Zone of Nigeria. It comprises about 16 autonomous communities and share common boundary with villages like Ohaji/Egbema, Mbaitoli, and the area has a total landmass of about 3,787 square km. The area is sandy-loamy and some sandy-clay loam that has made the zone good for agriculture. It has mean annual rainfall of about 2250 -3000mm that begin from the months of March to October, and the temperature ranges from 35 0 C -37 0 C. It is situated within tropical rainforest that has evergreen broad leaves. Traffic flow in this area is very slow coupled with the police check point that retarded the flow and vehicles spent 30 -45 minutes with their engines steaming.

(b) Soil Samples Collection Techniques:
The study site considered for the present study was Avu-Port Harcourt Roads with heavy vehicular flow where soil samples were collected at graded distances of 50m, 100m, 150m and 200m away from the road side, and two soil samples were collected from each points at the depths of 0.30 and 30-40 m respectively. Samples collected were analyzed for the following: (1) Soil Factors such as soil pH, soil temperature and soil moisture (2) Heavy Metals such as Lead (Pb), Cadmium (cd), Copper (cu), Zinc (zn), and Nickel (Ni) and , (3) Microbial Population to include fungal, and bacterial

(c) Laboratory Analytical Techniques:
For analyses in the laboratory, soil factor such as soil pH, soil temperature (ST), and soil moisture content (SMC), and bacterial counts (BC) were also observed.pH of sampled soils were determined from supernatant obtained after 1:1 (w:v ) mixture of the soil samples were made with sterile distilled de-ionized water. The pH was further measured using a PYE UNICAM model 291 mkz pH meter with a combined glass electrode. The temperature of each soil sampled was measured using Mercury-in-glass thermometer that was inserted into the affected soil for 20-30cm beneath the soil for 5minutes to stabilize for accurate reading, and was done onsite.
For the determination of soil moisture content of each soil sampled, APHA (1985) was used for the measurement. 10 grams of each soil sample was heated in a hot air for 8-12 hours at 80 O C till constant weight was obtained. The difference between the original weight and the consistent final weight obtained was taken as the weight of the moisture content of the soil samples. Fungal populations were estimated by Warcup's soil plate method using rose bengal agar medium. The inoculated plates were incubated at 25±1°C and colony forming units were enumerated after 5 days. Dilution plate method was used to estimate bacterial populations developing on nutrient agar medium. The inoculated plates were incubated at 30±1°C and colony forming units were enumerated after 24 h from the plate of higher dilutions (Prescot et al, 1988).

RESULTS AND DISCUSSION
The results of the study are presented in Table 1-Table 4. From Table 1, the result shows that soil factors such as pH, soil temperature and soil moisture varied considerably. At the distant of 50m with the depth of the soil within 0 -45cm soil pH varied between 4.52 -5.10, soil temperature 21 -25 0 C, and 10 -10.1 %. At 100cm, soil pH at the same depth ranged between 5.15 -5.17, soil temperature 21 -23 0 C, and soil moisture 10.01 -10.1%. At 150 cm and 200cm, soil Ph ranged between 5.75 -5.96, soil temperature 18 -19 0 C, Soil moisture 10.6 -11.1% and soil pH ranged between 6.25 -6.32, soil temperature 22 -24 0 C, and soil moisture ranged between 13.1 -13.3% respectively. The results further indicated that soil pH from the main road is more acidic than soil sampled away from the main road that moves toward alkalinity, and the IJAAS Verification of Vehicular Emitted Aerosol Components in Soil Biochemical Characteristics top soil at the depth of 0-30cm was also more acidic than depths, the top soil had an increased in temperature than the sub with distant. The same trend is found in soil moisture which is influenced by heat intensity from am temperature. Source: Fieldwork, 2010 Verification of Vehicular Emitted Aerosol Components in Soil Biochemical Characteristics 30cm was also more acidic than soil depth of 30 -45 cm ( depths, the top soil had an increased in temperature than the sub-soil and the surface temperature decreases with distant. The same trend is found in soil moisture which is influenced by heat intensity from am   (Figure 1). At the same soil and the surface temperature decreases with distant. The same trend is found in soil moisture which is influenced by heat intensity from ambient  From the results, it is further observed that heavy metal concentrations were hig the depths of 0-30cm and the concentrations decreased with distance from the road side ( then indicated soil being polluted by heavy vehicular flows. The results is further explained by authors like Ihenyen (1992), Weckwerth (2001), who attributed high degree of heavy metal contamination in the soil due to motor vehicles. Dierkes and cadmium and zinc are the most common metals that accumulates results indicated that cadmium had the highest percentage of concentration in the soil followed by ni third copper.   Table 3 refers to the bacterial population in the soil at the graded distant away from the roadside. From the results, some bacterial populations showed an roadside while some showed increasing trend with increasing distant away from the roadside. For instant thermophillus Bacilli bacterial population that can survive under an increased temperature Pagotto e (2001), indicating that at 50m with the soil depth of 0 with the soil depth of 0-30 cm the TB was less ( like Streptococcus Cremoris which also survive at the lower temperature with the present of organic matter or availability of organic substrates in the soil away from the roadside (Mishra, 2001). (1984) and nickel had a total concentration of 9.10kg with mean of 1.14, standard deviation of 10.9 and coefficient of 90.9% respectively. And according to Parry et al (1981), Joshi et al (1991), metals concentrations in the roadsides like lead is caused by leaded gasoline, tire wear, lubricating oil , grease and g; zinc is caused by tire wear, motor oil, engine parts, brake emission; copper, cadmium and nickel are caused by bearing wears, fuel burning, batteries and lubricating oil.
From the results, it is further observed that heavy metal concentrations were hig 30cm and the concentrations decreased with distance from the road side ( then indicated soil being polluted by heavy vehicular flows. The results is further explained by authors like Weckwerth (2001), who attributed high degree of heavy metal contamination in the soil due Geiger (1999) viewed that among the larger number of heavy metals, lead cadmium and zinc are the most common metals that accumulates in the roadsides soils. But, the overall results indicated that cadmium had the highest percentage of concentration in the soil followed by ni  Table 3 refers to the bacterial population in the soil at the graded distant away from the roadside. From the results, some bacterial populations showed an increasing trend with decreasing distant from the roadside while some showed increasing trend with increasing distant away from the roadside. For instant bacterial population that can survive under an increased temperature Pagotto e (2001), indicating that at 50m with the soil depth of 0 -30 cm, the TB was more in population, while at 200 m 30 cm the TB was less (Figure 3). This trend was experienced in bacterial population which is equally attributed to high temperature from the roadside, and it could also survive at the lower temperature with the present of organic matter or availability of organic substrates in the soil away from the roadside (Mishra, 2001).

Heavy Metals at Different Depths and Distant
ISSN: 2252-8814 f 1.14, standard deviation of 10.9 and coefficient of 90.9% respectively. And according to Parry et al (1981), Joshi et al (1991), metals concentrations in the roadsides like lead is caused by leaded gasoline, tire wear, lubricating oil , grease and g; zinc is caused by tire wear, motor oil, engine parts, brake emission; copper, cadmium and nickel are From the results, it is further observed that heavy metal concentrations were higher in the top soils at 30cm and the concentrations decreased with distance from the road side ( Figure 2). And these then indicated soil being polluted by heavy vehicular flows. The results is further explained by authors like Weckwerth (2001), who attributed high degree of heavy metal contamination in the soil due Geiger (1999) viewed that among the larger number of heavy metals, lead, in the roadsides soils. But, the overall results indicated that cadmium had the highest percentage of concentration in the soil followed by nickel and  Table 3 refers to the bacterial population in the soil at the graded distant away from the roadside. increasing trend with decreasing distant from the roadside while some showed increasing trend with increasing distant away from the roadside. For instant, bacterial population that can survive under an increased temperature Pagotto et al 30 cm, the TB was more in population, while at 200 m 3). This trend was experienced in bacterial population is equally attributed to high temperature from the roadside, and it could also survive at the lower temperature with the present of organic matter or availability of organic substrates Conversely Streptococ inversion in the soil this then lead to complete extinction. Above all, others could not survive the increased in temperature closed to the roadside, but survived away with increased popul eunpae was completely not available in the soil attributed to it susceptibility to environmental factors. The results of this kind is in line with the report of air pollution on soil microbe by Brookes et al (1986), who observed 41.6 percent reduction in soil species quantity, 37.5 percent in species density, 69.5 percent reduction in dominance of oribatida (1996) observed a decrease in abundance of m increasing distance from the source of emission. The reduction of microbial activity in the roadside soil due to vehicular pollution has been confirmed by authors Brookes et al (1986) .Redu community showed a significant decline from main road, and the reduction was suggested to be the result of heavy metal concentrations in the soil at distant that ranged between 50 the finding of (Joshi et al, 1991). From Table 4, fungi population densities are higher in 200m, 150 and 100m away from the roadside, while there is decrease in fungi population at 50m along the roadside. The decrease in number of soil microbes can be attributed to the effects of vehicular flows that emits along the road side. The result is consistent with the finding of (Acea and Carballa, 1985;Nwaugo et al, 2005).The results also indicated that greater number of microbes such Strolnifer, Mucor hiemalis, Mucor miehei, Penicillium spp, Ailernaria tenniss, isolated at 50m (Brookes, et al, 1986;Chessbrough, 1987) stated that good spore formers can survive within harsh environmental conditions like in the 50m ISSN: 2252-8814

Verification of Vehicular Emitted Aerosol Components in Soil Biochemical Characteristics
Variations of Bacterial Population in the Soil with Distance from the Roadside Streptococcus Cremoris and, Bacillus Spp could not survive lower temperature inversion in the soil this then lead to complete extinction. Above all, others could not survive the increased in temperature closed to the roadside, but survived away with increased population. Genera like was completely not available in the soil attributed to it susceptibility to environmental factors. The results of this kind is in line with the report of air pollution on soil microbe by Brookes et al (1986), who erved 41.6 percent reduction in soil species quantity, 37.5 percent in species density, 69.5 percent oribatida due to air rich in heavy metals. Williamson and Evans (1973), Post et al (1996) observed a decrease in abundance of mites due to the high level of inorganic lead in the soil with the increasing distance from the source of emission. The reduction of microbial activity in the roadside soil due to vehicular pollution has been confirmed by authors Brookes et al (1986) .Reduction of bacterial and fungal community showed a significant decline from main road, and the reduction was suggested to be the result of heavy metal concentrations in the soil at distant that ranged between 50 -200m. The result is consistent with ing of (Joshi et al, 1991).
ungi population densities are higher in 200m, 150 and 100m away from the roadside, while there is decrease in fungi population at 50m along the roadside. The decrease in number of soil microbes can be attributed to the effects of vehicular flows that emits heavy metals and the wearing of tire along the road side. The result is consistent with the finding of (Acea and Carballa, 1985;Nwaugo et al, 2005).The results also indicated that greater number of microbes such Aspergillus fumigatus Mucor hiemalis, Mucor miehei, Penicillium spp, Ailernaria tenniss, isolated at 50m (Brookes, et al, 1986;Chessbrough, 1987) stated that good spore formers can survive within harsh environmental conditions like in the 50m soil samples.

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Variations of Bacterial Population in the Soil with Distance from the Roadside could not survive lower temperature inversion in the soil this then lead to complete extinction. Above all, others could not survive the increased in ation. Genera like Nitrosomonas was completely not available in the soil attributed to it susceptibility to environmental factors. The results of this kind is in line with the report of air pollution on soil microbe by Brookes et al (1986), who erved 41.6 percent reduction in soil species quantity, 37.5 percent in species density, 69.5 percent due to air rich in heavy metals. Williamson and Evans (1973), Post et al ites due to the high level of inorganic lead in the soil with the increasing distance from the source of emission. The reduction of microbial activity in the roadside soil due ction of bacterial and fungal community showed a significant decline from main road, and the reduction was suggested to be the result of 200m. The result is consistent with x 10 x 7 x 4 x 7 x 9 -x 1 -x 3 x 4 x 5 x 6 x 8 x 12 x 2 x 3 x 4 -ungi population densities are higher in 200m, 150 and 100m away from the roadside, while there is decrease in fungi population at 50m along the roadside. The decrease in number of soil heavy metals and the wearing of tire along the road side. The result is consistent with the finding of (Acea and Carballa, 1985; Nwaugo et al, Aspergillus fumigatus , Rhizopus Mucor hiemalis, Mucor miehei, Penicillium spp, Ailernaria tenniss, and Themonye were isolated at 50m (Brookes, et al, 1986;Chessbrough, 1987) stated that good spore formers can survive

SUMMARY AND CONCLUSION
From the results, it is observed that soil pH was lower at 50m from the roadside indicating acidity in the soil which affect productivity of the soil the reflected the stunted plant growth near the roadside. Soil temperature was also identified along the roadside with decreased soil moisture at decreased distant. Also heavy metals were found closed to the main road. Similarly greater number of bacteria and fungal were found in greater population at distance away from the soil samples closed to the roadside. This has affected the activities of microorganisms the would have helped in decomposition process for mineralization and mobilization of soil nutrients. It is then concluded that since there is little or no human activity along the roadside, heavy traffic has caused the declined in the microbial population in the study area.
It is the recommended that, for sustainable soil quality management for food production: (1) Affected soil with low pH should be limed (2) Ring -roads should be constructed to divert traffic in Owerri west (3) Maintenance of vehicles should be monitored by vehicles inspection officers (VIO) to make sure that vehicles are not smoked unnecessarily. (4) Exotic trees should be planted linearly for gaseous exchange for air quality (5) The soil that is heavily contaminated with lead should not be used for growing of food crops but for ornamentals trees. (6) Farmers working on the contaminated soil should wear gloves and shoes to avoid self contamination (7) And farmers should remove gloves and shoes at the doorway to avoid tracking soils indoors where children play on the floor.