Determination of lead, cadmium and chromium in the tissue of an economically important plant grown around a textile industry at Ibeshe, Ikorodu area of Lagos State, Nigeria.Introduction
Pollution is correlated with the degree of industrialization industrialization
Process of converting to a socioeconomic order in which industry is dominant. The changes that took place in Britain during the Industrial Revolution of the late 18th and 19th century led the way for the early industrializing nations of western Europe and and the intensity of chemical usage. Past and present industrial activities have often resulted in the pollution of underlying soils where these activities take place, either by leaching of water from landfills or direct discharge of industrial wastewater into soil . These industrial wastewaters are produced mainly and in large quantities by textile industries , due to the nature of their operations, which require high volume of water that eventually results in high wastewater generation. The most common toxic soil pollutants include heavy metals heavy metals,
n.pl metallic compounds, such as aluminum, arsenic, cadmium, lead, mercury, and nickel. Exposure to these metals has been linked to immune, kidney, and neurotic disorders. and their compounds, organic chemicals, oils, tars and pesticides . Soil pollution by heavy metals such as mercury, cadmium, chromium and lead are of great concern to public health . The source of heavy metal in plant is the environment in which they grow and their growth medium (soil) from which heavy metals are then taken up by roots or foliage of plants . Plants growing in polluted environment can accumulate heavy metals at high concentration causing serious risk to human health when consumed . Moreover, heavy metals are [4,23,6] dangerous because they tend to bioaccumulate in plants and animals thereby causing deleterious effects, bioconcentrate in the food chain or attack specific organs in the body .
Ingesting large amount of heavy metal like chromium, cadmium and lead can cause reduced litter size and weight, liver and kidney damage kidney damage Kidney injury Nephrology A structural or functional compromise in renal function due to external–eg, athletic, occupational, or other trauma, resulting in bruising or hemorrhage, which can be profuse and life threatening Etiology Vascular . Cadmium can also accumulate in kidney where it damages filtering and causes excretion of essential proteins and sugar from the body . In herbaceous her·ba·ceous
1. Relating to or characteristic of an herb as distinguished from a woody plant.
2. Green and leaflike in appearance or texture. plants, roots and leaves retain higher metal concentration of heavy metal than stems and fruits . Therefore, there is need to know the concentration of heavy metals in crops particularly leafy vegetables which are consumed by humans. Over time, the soils within the vicinity of a textile industry in Ikorodu area of Lagos State in Nigeria have been used by residents for the cultivation of vegetables. This is probably due to the high volume of wastewater generated from the industry, which serves as a means of irrigation irrigation, in agriculture, artificial watering of the land. Although used chiefly in regions with annual rainfall of less than 20 in. (51 cm), it is also used in wetter areas to grow certain crops, e.g., rice. for their vegetable gardens. This is because the vegetable growers believe wastewaters from industries contain a lot of nutrients that can support and promote a high yield of vegetables. Talinum triangulare is an herbaceous perennial plant which is an all season vegetable and it is extensively grown in Nigeria. It serves as a nutritious source of food for both man and livestock because it contains vitamins A, C and mineral like calcium. Though it is consumed most times without consideration of its medicinal values, Talinum triangulare is medicinal and can be used for the treatment of diuretic diuretic (dī'yərĕt`ĭk), drug used to increase urine formation and output. Diuretics are prescribed for the treatment of edema (the accumulation of excess fluids in the tissues of the body), which is often the result of underlying and stomach problems  .
In this study, Talinum triangulare which is the dominant leafy vegetable in the gardens around the textile industry was used to determine the level of heavy metal pollution that might have been caused by the operations of the textile industry.
Materials and methods
The sampling was done around the surrounding of United Nigeria Textile PLC (UNT UNT University of North Texas
UNT Upsala Nya Tidning (Swedish newspaper)
UNT Universidad Nacional de Tucumán (Argentina)
UNT Unión Nacional de Trabajadores ), which is located in Ibeshe town near Ikorodu, Lagos state. The textile industry occupies a large expanse of land in the vicinity while banks and residential houses occupy the neighboring land. The industry is located along a major express road. Very tall palm trees and vegetable gardens abound within the surrounding of this industry. The industry produces large amount of wastewater and this water flows through the soil to the surrounding gardens.
Description of sampling points
Three different points (A, B and C) 50 M around the textile industry were sampled for soil and plant while the fourth sampling point is located in a non-industrial area about 500 M away from the industry. The samples from this point served as control and the point was designated as D. A map of the different sampling points is shown in Figure 1.
Collection of plant and soil samples
Two soil and plant samples each were collected from points A, B, C and D. Plant samples were collected carefully using hand trowel to dig the soil around the plant and the plants were pulled out carefully, ensuring that no part of the root was lost. The different plant samples were kept in different polythene pol·y·thene
n. Chiefly British
Variant of polyethylene.
[poly- + (e)th(yl)ene. bags and properly labeled.
Soil samples were collected from the same point where the plant samples were uprooted. The soil samples were collected to a depth of 15cm using a soil auger. The soil samples were kept in polythene bags and labeled to avoid a mix-up of the different soil samples. The plant and soil samples were brought to the Environmental Biology laboratory and kept in the fridge prior to analysis for heavy metals.
Each plant sample was separated into leaves, roots, and stems and then dried at 50[degrees]C for 8 hours using an oven. The dried plant samples were milled using a laboratory blender and kept for digestion. Unwanted materials such as stones, leaves and debris were removed from the soil samples by hand-picking. The soil sample was further broken down into finer particles using a laboratory mortar and pestle A mortar and pestle is a tool used to crush, grind, and mix substances. The pestle is a heavy stick whose end is used for pounding and grinding, and the mortar is a bowl. The substance is ground between the pestle and the mortar. . The soil samples were dried for 8 hours at 80[degrees]C using an oven.
Soil and plant samples were digested before analysis to reduce organic matter interference and allow for the conversion of the metal into a form that can be analyzed by the Atomic Absorption Spectrophotometer spectrophotometer, instrument for measuring and comparing the intensities of common spectral lines in the spectra of two different sources of light. See photometry; spectroscope; spectrum. (AAS).
Plant sample digestion
Plant samples were digested following the method of Allen et al., 3g of the milled plant sample were weighed into a conical flask using a digital weighing balance. 3 ml of 60% hydrochloric acid hydrochloric acid: see hydrogen chloride.
or muriatic acid
Solution in water of hydrogen chloride (HCl), a gaseous inorganic compound. and 10 ml of 70% nitric acid were added to the weighed milled plant sample. The conical flask was then placed on a laboratory hot plate for digestion until the white fume fume Occupational medicine A solid suspension resulting from condensation of the products of combustion. See Inhalant Vox populi verbTo be in the midst of a mental mini-meltdown. evolving from the conical flask turned brown. The digest was allowed to cool and then filtered through a Whatman's filter paper, leaving a whitish residue. The filtrate filtrate /fil·trate/ (fil´trat) a liquid or gas that has passed through a filter.
To put or go through a filter.
n. was then made up to 50 ml using distilled water and kept for further analysis.
[FIGURE 1 OMITTED]
Soil sample digestion
The same procedure for the digestion of plant sample was used according to the method of Allen et al.
Determination of Heavy Metals in the Digested Samples using Atomic Absorption Spectrometer (AAS)
The digested plant and soil sample were analyzed for lead (Pb), cadmium (Cd) and chromium (Cr) using Atomic Absorption Spectrometer (AAS).
The readings were taken from the equipment and the results were converted to actual concentration of metals in the samples using the equation;
Concentration [micro]g/g = Extract volume Calibration reading x--Sample weight
Where calibration reading is the value of the reading obtained from the AAS equipment Extract volume is the final volume of the digest used for spectrometric analysis
Sample weight refers to the weight of the sample used. After which the mean of the heavy metal concentrations in soils from the industrial and non-industrial sites were then calculated.
The Multiplication Coefficient (MC) or Bioconcentration Fa ctor (BCF BCF Billion Cubic Feet
BCF Bioconcentration Factor
BCF British Chess Federation
BCF British Coatings Federation
BCF Breast Cancer Fund
BCF Bank Credit Facility
BCF Bulked Continuous Filament
BCF British Cycling Federation
BCF Boeing Converted Freighter ) according to Joonki et al, was also calculated using the equation:
Concentration of R ([micro]g/g)/ Concentration in S ([micro]g/g)
Where concentration of heavy metal in R is the concentration of heavy metal in the roots and concentration of heavy metal in S is the concentration of heavy metal in soil.
Determination of Soil pH
The soil pH was determined following the method of Eckerts and Sims. The soil samples were first air-dried and 5 g of the air-dried soil was mixed with 5 ml of distilled water and stirred. The mixture was allowed to stand for thirty minutes to allow it to settle. The slurry was decanted into a test tube.
The electrode of a pH meter was put into the slurry and the pH read off.
Results and discussion
The results of the chemical analysis of lead (Pb), cadmium (Cd), and chromium (Cr) in soil and plant samples collected are presented in Table 1. The pH of soils from both industrial (5.92[+ or -]0.02) and non-industrial (6.02[+ or -]0.01) areas are slightly acidic. The concentrations of lead, cadmium and chromium are higher in soil samples obtained from the textile industry area when compared with those obtained from the non-industrial area. Lead and cadmium concentrations of the soil from the industrial area were significantly higher than those of the non-industrial area (Table 1). But generally the concentrations of the three heavy metals are low as it has been previously reported for soils in Nigeria [3,4]. Table 2 shows the concentrations of the heavy metals in the tissue of the plant. The concentrations of the heavy metals in the plant tissue were higher in the industrial area than the non-industrial area however chromium was not detected in the tissue of plants from non-industrial area. The concentrations of the three heavy metals in plant tissues from the industrial area were also higher than from non-industrial area at P<0.05 (Table 2). Table 3 shows the rate at which the roots of T. triangulare bi-accumulates these heavy metals as shown by the Multiplication Coefficient (MC) or Bio-concentration Factor (BCF). The soils of both industrial and non-industrial areas have more of the heavy metals than the roots of the vegetable except for cadmium concentration in the roots of vegetables from the industrial area. The MC or BCF for Pb and Cr in both study areas are less than one, while that for Cd in the industrial area is greater than one, with MC or BCF value of Cd from the industrial area being the highest. Generally, these MC/BCF values are low because of low levels of the heavy metals in the roots (Table 3).
The concentration of Pb, Cd and Cr in the soil was higher in soil samples from the industrial site compared with the non-industrial site. There is no doubt that heavy metals are present in soil naturally and non-degradable, and can be accumulated in the plant tissues [3,17] as shown by the concentrations of heavy metals obtained in soils from non-industrial site, but their concentrations can be increased by industrial activities . In this case, chemicals such as dyes and other finishes used on the fabrics can lead to an increase in the concentration of heavy metals in the soils. This is similar to the observation of Abdulkaaheem and Singh  in which heavy metals like Cd, Cr, Cu, Pb and Zn in soil and plants samples around tannery and textile industries decreased as the distance from point of effluent diacharge increased. Fakayode and Onianwa  made similar observation noting that plant and soil samples from industrial sites contain more heavy metals than those from non-industrial sites. Moreover, direct and indirect discharges of industrial effluents, dumping of metallic products and atmospheric deposit can lead to high levels of heavy metals in soils and water bodies . The high levels of heavy metals in the shoots of T. triangulare obtained in this study are similar to those observed by Akinola and Njoku . This observation calls for caution because it is the shoot portion of this popular pot herb that is consumed by the people. Heavy metals are known to be biomagnified in the tissues of the consumers along the foodchain. Moreover, the short foodchain between plant and man as an herbivore herbivore: see carnivore.
Animal adapted to subsist solely on plant tissues. Herbivores range from insects (e.g., aphids) to large mammals (e.g., elephants), but the term is most often applied to ungulates. makes the efficiency of transfer from plant to man very high . Hence the level of heavy metals in man can easily increase. It is opined that cultivation of vegetables around industrial areas should be minimized and discouraged as much as possible. This is because of its implication to human health. For instance, lead has been found to be toxic to the red blood cell red blood cell: see blood. , kidney, nervous and reproductive systems . Excess of cadmium has been reported to cause renal tubular dysfunction accompanied by osteomalacia osteomalacia /os·teo·ma·la·cia/ (os?te-o-mah-la´shah) inadequate or delayed mineralization of osteoid in mature cortical and spongy bone; it is the adult equivalent of rickets and accompanies that disorder in children. (bone softening) and other complications which can lead to death . Although the levels of the heavy metals in the tissue of T. triangulare in this study were less than the values recommended as the minimum intake values. However, continuous consumption of the vegetable from this site is not advisable. The quantity of the vegetable which is usually consumed is a lot more than the small quantity which is used for analysis of heavy metal concentrations. This implies that the heavy metal levels can be more in the quantity of the vegetable consumed. Furthermore, heavy metals are known to bio-accumulate in the tissue of organisms at higher trophic trophic /tro·phic/ (tro´fik) (trof´ik) pertaining to nutrition.
Of, relating to, or characterized by nutrition. levels, so continuous consumption of the vegetable may lead to increase in the levels in humans. It has been noted that more heavy metals are absorbed by plants when pH is as low as 2-3 . So the pH of near neutral recorded for the soils could be the cause of low uptake of Pb and Cr by the vegetable  thereby leaving a higher concentration of the two heavy metals in the soil than the concentration in the root. A high pH value has been found to cause immobilization Immobilization Definition
Immobilization refers to the process of holding a joint or bone in place with a splint, cast, or brace. This is done to prevent an injured area from moving while it heals. of heavy metals in the soil. This can further explain the low concentrations of these metals in the roots of the crops. But these concentrations become magnified as they move up from the roots to the shoot portion of the crops. This also explains the generally low magnification coefficients/bioconcentration factors (MC/BCF) recorded in this study.
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Akinola, M.O., Njoku, K.L. and Ekeifo, B.E.
Environmental Biology, Laboratory, Department of Cell Biology & Genetics, University of Lagos The University of Lagos (also known as Unilag) is a federal government university with a main campus located at Akoka, Yaba and a college of medicine located at Idi-Araba, all in Lagos, Lagos State, southern Nigeria. , Akoka, Lagos, Nigeria.
Akinola, M. O., Environmental Biology, Laboratory, Department of Cell Biology & Genetics, University of Lagos, Akoka, Lagos, Nigeria Email: firstname.lastname@example.org
Table 1: Mean concentration of heavy metals Lead, Cadmium and Chromium ([micro]g/g) in soil samples. Sampling Points Soil pH Lead (Pb) Textile industry area 5.92 [+ or -] 0.02 10.89 [+ or -] 4.69 Non-industrial area 6.02 [+ or -] 0.01 2.33 [+ or -] 0.01 Sampling Points Cadmium (Cd) Chromium (Cr) Textile industry area 0.81 [+ or -] 0.01 12.50 [+ or -] 3.18 Non-industrial area 0.65 [+ or -] 0.08 12.48 [+ or -] 1.21 Table 2: Mean concentrations of heavy metals ([micro]g/g) in tissues of T. triangulare. Heavy Metal Plant Sampling Site tissues Industrial area Non-industrial area Lead Root 0.71 [+ or -] 0.59 0.60 [+ or -] 0.25 Stem 0.23 [+ or -] 0.19 0.16 [+ or -] 0.01 Leave 0.86 [+ or -] 0.68 0.74 [+ or -] 0.56 Cadmium Root 1.22 [+ or -] 0.32 0.63 [+ or -] 0.05 Stem 1.21 [+ or -] 0.40 0.73 [+ or -] 0.05 Leave 1.25 [+ or -] 0.37 0.86 [+ or -] 0.06 Chromium Root 1.51 [+ or -] 0.37 ND Stem 2.78 [+ or -] 0.48 ND Leave 65.60 [+ or -] 39.74 1.21 [+ or -] 0.12 ND--Not Detected Table 3: The concentration of heavy metals in soils in relation to its concentrations in plant roots as shown by the multiplication coefficient/bio-concentration factor (MC/BCF). Sampling Site Lead Cadmium Industrial area Root 0.71 [+ or -] 0.59 1.22 [+ or -] 0.32 Soil 10.89 [+ or -] 4.69 0.81 [+ or -] 0.01 MC/BCF 0.07 1.51 Non-industrial Root 0.60 [+ or -] 0.25 0.63 [+ or -] 0.05 area Soil 2.33 [+ or -] 0.01 0.65 [+ or -] 0.08 MC/BCF 0.26 0.97 Sampling Site Chromium Industrial area 1.51 [+ or -] 0.37 12.50 [+ or -] 3.18 0.12 Non-industrial ND area 12.48 [+ or -] 1.21 0 ND- Not Detected