Fifty percent of Nigeria’s industrial activities including 300 industries in 12 industrial estates are located in the Lagos area [1] . The high urbanization and industrial growth rate in Lagos had made it one of the most densely populated regions on the earth with a population of about 9.3 millions according to 2006 Census [2] . Thus, the continuous increase in population and industrial growth in Lagos persistently cause large volume of wastes to be generated industrially and domestically [1] . Industries have largely been responsible for discharging untreated effluents containing trace metals such as zinc (Zn), copper (Cu), manganese (Mn), cadmium (Cd), mercury (Hg), nickel (Ni), lead (Pb), Iron (Fe) and Chromium (Cr) improperly into our environments [3] -[5] . Soils and plants in nearby zone of industrial areas display increased concentration of heavy metals, serving in many cases as sinks of pollution loads [6] . Plants around industries take up large quantities of pollutants which they translocate into vegetative and generative organs at various rates [7] [8] . However, pollution in developing nations is correlated with the degree of industrialisation and the intensity of chemical usage [9] -[11] .

The concentrations of heavy metals in animals have harmful effects especially when consum above the bio-recommended limits from plants [12] . Although individual metals exhibit specific signs of their toxicity, the followings have been reported as general signs associated with cadmium, lead, iron, zinc, and copper poisoning: gastrointestinal (GI) disorders, diarrhoea, stomatitis, tremor, hemoglobinuria causing a rust-red colour to stool, ataxia, paralysis, vomiting and convulsion, depression, and pneumonia when volatile vapours and fumes are inhaled [13] . The nature of effects can be toxic (acute, chronic or sub-chronic), neurotoxic, carcinogenic, muta- genic or teratogenic [12] .

The overall objective of this study is to investigate the influence of industrial activities and associated processes with heavy metal contamination of soils and vegetation in Lagos city, and comparing heavy metal contents in soils and that of the plants (Bioaccumulation). Information being obtained can assist in identifying and subjecting bioaccumulators for remediation of polluted soils.

High values of copper observed generally in this study are consistent with values reported by [18] [19] . They identified plants to greatly uptake Cu, Cd and Zn. Cu exhibited considerable variations from location to location with the highest value observed at Egbin thermal station although still within the range of International threshold values for copper concentration in soils. Comparison of the Cu concentration in all sampled plants showed that it is higher in plants located in the vicinity of the thermal station. Melting, grinding or the cutting of copper, and emission from electricity cables, may produce fumes and dust, and exposure or inhalation of these fumes may produce potential health hazards [20] . Fumes of copper may cause metal fumes fever with flu-like symptoms and hair and skin discoloration in man although dermatitis has not been reported, it can also cause irritation of the upper respiratory tract, a metallic taste in the mouth and nausea [20] . [21] [22] explained that there are different tolerance ranges for plants, but a critical toxic level of Cu is in the range of 20 - 30 mg/kg for most plants. The risk of Cu toxicity in vegetation species is clearly evident by the fact that higher concentrations have been reported in this current study.

Cadmium is a toxic element and can cause serious health problems. The most common sources for cadmium in soil and plants are phosphate fertilizers, non-ferrous smelters, lead and zinc mines, sewage sludge application and combustion of fossil fuels [23] [24] . International threshold values for heavy metals concentration in soils for cadmium in soil are between 1.40 - 3 mg/kg [25] . At this level, in most cases, it is taken up metabolically and is easily transported to the other parts of the plant [26] . In this present study, Cd concentrations in all soil and plant samplesinvestigated in this presentstudy are low as also observed by [20] .

Zinc is essential element for plant growth, as it serves an important role in plant structure and function [27] , it is a natural constituent of soils in terrestrial ecosystem and it is taken up actively by roots [28] . In this study, there is slight pollution of Zn in the textile, paint and the thermal station with the highest concentration observed in soil of Egbin thermal station. The high concentrations of the soil could have negative effects on soil microbial population and activities [29] , provoking a low organic matter mineralization during the plant growth. These results are line with the findings of [30] which observed the soils of Industrial area to be slightly polluted with Zn.

Iron is another essential element for plant and animalgrowth. Its deficiency can cause various types of diseases; however, its high concentration also affects plant growth. Iron concentration levels in soil samples collected from all locations showed no significantdifferences with the heavy metals in plants of same sites. However, the observed concentrations of Fe in plants are slightly higher than those in soils and none is beyond the regulated standards.

Lead is regarded as highly hazardous for plants, animals and particularly for microorganisms. The main sources of lead pollution in agriculture and plants are lead mines, combustion of leaded hydrocarbon, sewage sludge applications and farmyard manure, industrial processes etc. [20] . In this study the concentration Pb in 25% of the plants were higher than the maximum acceptable range of 0.3 - 2.0 mg/kg for plants. The highest concentrations of Pb in soils were observed in Sunflag group (spintex) and Nichemtex. The concentration of Pb in soil is of a significant interest as it is far higher than what [30] recorded in a similar study in the vicinity of Sunflag group (spintex). These high concentrations of Pb in soils indicate high amount of Pb in textile effluents. This result is in line with the findings of [30] -[32] .

Plant species, physiological stage, uptake capability as well as growth rate are major determinants of metal transfer from soil to the crop [6] . The ability of plants to tolerate and accumulate these metals may provide the bases for their phytoremediation usefulness. Bioconcentration factor (BCF) can be used to assess a plant’s potential for phytoremediation purposes. The highest BCF value for Zn and Cu was observed in Croton lobatus, for Fe it was observed in Cyathula prostrata, for Pb it was observed in Borreria sp. while Corchorus oliterus had the highest BCF for Cd.

In an attempt to understand the relationship between the concentrations of corresponding metals evaluated from the soil and plant samples, the Pearson Correlation Co-efficient, r, was used. There are positive correlation between soil and plants for all the metals in all the investigated areas. These relations were significant (p < 0.05) for Cu, Fe, Pb and Cd but not significant for Zn under the current study. The results of positive correlation between soil and plants have been supported by earlier research findings by [33] [34] . These positive relations indicate that plants take in nutritional elements from the soil through their roots. However, the negative correlation relation indicated by Zn, give a strong suspicion to the fact that some elements might be assimilated through other organs of the plants other than their roots. Such elemental intake may be directly through atmospheric deposition.

The findings in this study show that plants in the vicinity of industries have high risk of having heavy metal concentrations beyond the permissible limit if safety and environmental law are not enforced. This study confirms a relationship between the concentration of heavy metals in the plants and soils. Plants having BCF values less than one had limited ability to accumulate, translocate and phytoextract heavy metals (Fitz and Wenzel, 2002). Therefore, we recommend plants in this study with higher BCF value especially those greater than one (such as Croton lobatus, Borreria sp., Cyathula prostrata, Lantana camara, Ficus sp., Mimosa pudica, Eclipta prostrata, Commelina sp. etc.) be subjected for further research and assessment on their phytoremediation abilities.

The authors wish to thank Oluwafunmilayo Famakinwa-Adesuyi, Chinedu Anikpo, Adetokunbo Soyoye and Taibat Olajumoke Odukoya for their assistance during the field data gathering exercises and special thanks to the EIA Team, Environmental Dept. of Shell Petroleum Development Company in Nigeria, Port Harcourt, especially Prof Gabriel Umoh, Prof. Valerie Nnodu, Ajibade Temitope, Ngwoke Moses and Ojesanmi Adesola for their intellectual and invaluable contributions.

Adeola AlexAdesuyi,Kelechi LonginusNjoku,Modupe OlatundeAkinola, (2015) Assessment of Heavy Metals Pollution in Soils and Vegetation around Selected Industries in Lagos State, Nigeria. Journal of Geoscience and Environment Protection,03,11-19. doi: 10.4236/gep.2015.37002