Bioaccumulation of Heavy Metals in Soil and Vegetables

Bio ingathering of Heavy Metals in primer coat and VegetablesAbstractThe state contract was carried out to assess fundamental surfaces Cadmium (Cd), Lead (Pb), bull (Cu), coat (Zn), Chromium (Cr) and Nickel (Ni) levels in vegetables like Caulif humiliate (Brassica oleracea var. botrytis), Cabbage (Brassica oleracea), cultivated carrot (Daucus carota), Brinjal (Solanum me recollectiveena), Spinach (Spinacia oleracea) and Radish (Raphanus sativus) irrigated with home(prenominal) effluent. The vegetable samples were randomly roll up from the farmlands irrigated with national pretendy pissing a exposit the Hisar district. Spinach, sn are, carrot, egg coiffure and carrot accumulated postgraduateer(prenominal)(prenominal)(prenominal)(prenominal) Cd (1.300.31), Pb (4.230.32 mg kg-1), Cu (1.420.25 mg kg-1), Zn (3.40.28 mg kg-1), Cr (1.160.11 mg kg-1) and Ni (2.450.86 mg kg-1) independently. Transfer Factor (TF) of Cd, Pb, Cu, Zn, Cr and Ni atomic number 18 more in prickly -seeded spinach plant (0.0306), cabbage (0.4448), spinach (0.2642), cauliflower (0.2494), carrot (0.0764) and spinach (0.7469) respectively. The wellness risk assessment has been bet followed by Estimated Daily using up Metal (EDIM) and Estimated health Risk big businessman (EHRI). The present information lastlights that both matures and children consuming vegetables full-grown in waste wet irrigated skanks accumulate significant amount of these surfaces. However, the c be fors of these metals were lesser than recommended maximum permissible levels proposed by the FAO/WHO (1999).Keywords Daily use of goods and services, Heavy metals, Plant expenditure, Risk perspicacity, Reference dose, EDIM, EHRI introIndian economy is based on agriculture and having second largest tribe in the world. Most of its states are depends on the monsoon. There are two primary(prenominal) sources for irrigation. First one is canal and second is foothold water system but the bore of lay down water is so poor for the long sustainability of agriculture system. This water is not adequate to fulfill the crop water requirement and needs additional extra water for agricultural purposes. To supply the need of the present demand for irrigation, use of municipal domestic effluent, is change state a common practice in urban areas of Haryana, India. This practises proficient fusss of salt and ultimately reduction in agriculture production (Marsh whole et al., 2007, Singh et al., 2010). The large amounts of untreated in pass aroundrial and domestic wastewater are used for year round irrigation of vegetables. Such waste water usu anyy contains sarcoid metals that accumulate in the dirty word. The use of such untreated wastewater has been account to cause contaminations of the viands chain (Wang et al., 2004 Mapanda et al., 2005).Some trace amount of obtuse metals such as Zn and Cu are essential for the growth of organisms eon others such as Cd and Pb are toxi c (McBride, 1994, Kabata-Pendias and Mukherjee, 2007). Dietary uptake pathway could be through with(predicate) crops irrigated with contaminated wastewater and earn been reported to contain large amount of toxic intemperately metals which may flow to health dis separates in humans depending on the uptake of these metals into plant and consumed by animals or humans (Bosso and Enzweiler, 2008 Fu et al., 2008 Lim et al., 2008 Agbenin et al., 2009). Consumption of metal contaminated vegetables may broaden to a weakened immune system, intra-uterine growth retardation, impaired psycho-social behavior, eminent preponderance of upper gastrointestinal cancer and other disorders typically associated with malnutrition (Arora et al., 2008).Potential health risks to humans from utilisation of vegetables can be due to sarcoid metal uptake from contaminated soils via plant roots as well as direct deposition of contaminants from the atmosphere onto plant surfaces (McBride, 2003). A number o f preliminary studies from developing countries have reported heavy metal contamination in wastewater and wastewater irrigated soil (Cao and Hu, 2000 Mapanda et al., 2005 Nyamangara and Mzezewa, 1999 Singh et al., 2004 Nan et al., 2002). Dietary intake is the main route of mental picture of heavy metals for most people (Tripathi et al., 1997). The information close to heavy metal concent balancens in different type of vegetables and their dietetical intake is very important for assessing their risk to human health. Heavy metals in the fare cycle have seriously threatened health and environmental integrity, therefore, problem of heavy metal contamination in vegetables should be canvas in details to develop central strategies. The objective of present teaching was bioaccumulation of heavy metals in vegetables irrigated by domestic wastewater and assessment of health sour due to these heavy metals.Materials and methodsStudy area and sampling entirely samples were randomly coll ected from the farmlands irrigated with domestic wastewater around the three different posts such as Rishi Nager (L1), New Police Line (L2) and Ludass village (L3) of Hisar district of Haryana, India. nation samples were collected at the surface depth of 10cm using stainless blade spade sampling tools and plastic buckets to avoid any contamination of samples with traces of elements from the tools. At individually sampling site, scrape away surface debris and bump off a core sample to the appropriate depth. Soil samples were air dried, ground, passed through a 2mm sieve and stored in plastic bags for further analysis. Five ground Water and seven wastewater samples were also collected from the each location. in all samples were collected and stored and kept at 4oC for further analysis in polyethylene bags/canes according to their type and brought to the laboratory for metal quantification.Sample preparation alone the collected Vegetables were washed with double distilled water t o remove airborne particles. The viands parts of the samples were weighed and soils samples were air-dried at room temperature, to reduce water content. only the samples were then oven-dried in a hot air oven at 705 oC for 24 h. Dried samples were powdered using a crunch and mortar and sieved through muslin cloth.Digestion of the vegetable and soils samplesFor each vegetable, three powdered samples from each source of domestic wastewater irrigation (1.0 g each) were accurately weighed and placed in crucibles, three replicates for each sample. The soil and vegetable ash samples were digested with perchloric acid and nitrous acid (14) solution. The samples were left to cool and table of contents were filtered through Whitman filter newsprint No. 40. Each sample solution was made up to a final volume of 50 ml with distilled water and concentration of heavy metals were analyzed by atomic absorption spectrophotometer (ASS model AA6300, Shimadzu).Risk AssessmentTransfer Factor (TF)Th e transfer instrument (TF) of Cadmium (Cd), Lead (Pb), copper (Cu), zinc (Zn), Chromium (Cr) and Nickel (Ni) from the soil to vegetables were calculated using infra given equation 1(Cui et al., 2004 Gupta, et al., 2010)(1)Estimated Daily Intake of Metal (EDIM)The Estimated daily verbal intake of metals from soil through vegetables in mg was calculated by equation 2(2)Where Cm is heavy metals conc. in vegetable plants (mg/kg), CF is conversion broker, DI is daily intake of vegetables (kg/ almostbody/day) and BAw is Average body system of weights (kg). The conversion divisor used to convert fresh green vegetable weight to dry weight was 0.085, as described by rattan cane et al., 2005 caravansary et al., 2008, Arora et al., 2008). The total daily vegetable intakes for adults and children were considered to be 0.250 and 0.150 kg/ person/day, respectively, while mediocre body weights were taken as 55 and 25 kg of the age of 35 and 16 years respectively for adult and child.Esti mated Health Risk Index (EHRI)Estimated health risk index (EHRI) is the ratio of pass judgmentd daily intake of metal (EDIM) to the reference dose (RD) is defined as the maximum passable daily intake of a specific metal that does not result in any harmful health effects. If the value of EHRI less than one than the exposed population is said to be guard and if greater than one indicating that there is a potential risk associated with that metal (IRIS, 2003) was calculated by under given equation(3)Result and backchatMetal concentration level in water and soilThe calibre of domestic wastewater and ground water (tube well) was assessed for irrigation with respect to their pH, EC, OC and some of the heavy metals. The pH of the sewerage water in the scope of 6.8-7.3 (7.030.07) was lower than the ground water as collected from the nearby area in the ranged of 7.2- 7.9 (7.60.12) while its salt content (EC) was in the ranged of 175.8-195.3 mS/m considerably high than those of ground waters (148.9-158.6 mS/m). The concentration for heavy metal contents in domestic wastewater and in ground water samples shows that Cd, Pb, Cu, Zn, Cr and Ni (figure 1) are well within the limits permissible limit identify by FAO (1985) and PFA (2000). In general, concentrations of heavy metals were higher side in domestic wastewater than in the ground waters (Tube Well) which could be toxic to some crops and human health. In the studied area, the concentration of all the heavy metals in water and domestic wastewater were found to be higher overleap Zn from the permissible limits of Indian standards (PFA, 2000) and (WHO/FAO, 2007).The total concentrations of heavy metals (Cd, Pb, Cu, Zn, Cr and Ni) in soils sampled at the three different sites are presented in figure 2. The reasonable pH of the location-I (7.04011), location-II (7.020.19) and location-III (7.00.03) soil are almost nearly neutral. The electrical conduction (EC) was 190.2-273.6 mS/m for location-I, 202.8-247.2 mS /m for location -II and 170-271.3 mS/m for location-III. The percent constitutional coke contents in soil were higher due to constant domestic wastewater irrigation and ranged from 3.48-5.2% for location-I, 3.85-5.54% for location-II and 3-69-5.6% for location-III. As the sub soils were impenetrable the organic carbon was found to be in high percent. Soil organic carbon is the most important indicator of soil quality and in addition to acting as a store-house of the plant nutrients plays a major role in nutrient cycling (Rattan et al., 2005).Across the regard area, wide ranges of soil heavy metal concentration were spy and are shown in figure 3. The observed concentration of heavy metal in ranged between 37.76-73.5 mg kg-1 for Cd, 2.74-22.44 mg kg-1 for Pb, 0.54-24.16 mg kg-1 for Cu, 0.96-12.44 mg kg-1 for Zn, 3.21-72.85 mg kg-1 for Cr, 1.37-6.47 mg kg-1 for Ni, and 249.3-773.4 mg kg-1 for Fe for location-I. For location-II, heavy metals ranged between 23.7-103.7 mg kg-1 for Cd , 5.67-30.99 mg kg-1 for Pb, 3.04-16.47 mg kg-1 for Cu, 3.16-9.16 mg kg-1 for Zn, 3.19-41.35 mg kg-1 for Cr and 4.68-13.77 mg kg-1 for Ni 6.31-66.61 mg kg-1 for Cd, 3.20-19.60 mg kg-1 for Pb, 1.35-11.81 mg kg-1 for Cu, 4.47-15.55 mg kg-1 for Zn, 1.38-3.54-46.64 mg kg-1 for Cr and 1.38-9.99 mg kg-1 for Ni for location-III. The domestic wastewater irrigated soil in all locations, the heavy metal (Cd, Pb, Cu and Cr) concentrations was not significantly and for Zn and Cr is significant at (PThe results have clearly indicated higher concentration of metals in soils which is contributed lengthen irrigation by sewage wastewater. If the same trend continues the concentrations of metals will accumulate in the soil. comparatively higher amounts of these heavy metal which attributes to the reduction in soil pH to fairly acidic conditions as well increase in organic carbon due to the continuous use of sewage effluents. This may be a cause of prime concern in near future. Long-term operation of domestic wastewater will result in increase in organic carbon and decrease in pH.Heavy metal accumulation in vegetablesThe concentrations of heavy metals in pabulum part of vegetables (Table 3 and figure 2) were investigated in vegetables which is commonly grown. The bioaccumulations of heavy metals concentration in all the vegetables are different, so no similar trend have been observed for heavy metal concentration. The heavy metals bioaccumulation in cauliflower was Zn Pb Cu Ni Cd Cr, for cabbage was Pb Zn Cd Cr Cu Ni, for carrot was Zn Pb Ni Cu Cr Cd, for brinjal Zn Pb Cd Ni Cr Cu, for spinach was Zn Ni Pb Cd Cu Cr , a similar trend have also been observed by Pandey and Pandey (2009) and for daikon Zn Ni Pb Cr Cu Cd.Cauliflower accumulated in the range of 0.15-0.27 mg kg-1 Cd, 0.14-0.34 mg kg-1 Pb, 0.7-1.75 mg kg-1 Cu, 2.9-5.9 mg kg-1 Zn, 0.10-0.35 mg kg-1 Cr and 0.01-0.60 mg kg-1 Ni, cabbage accumulated 0.30-1.20 mg kg-1 Cd, 3.37-5.37 mg kg-1 P b, 0.06-1.10 mg kg-1 Cu, 0.74-4.90 mg kg-1 Zn, 0.06-1.23 mg kg-1 Cr and 0.01-0.34 mg kg-1 Ni, carrot accumulated 0.20-0.70 mg kg-1 Cd, 0.98-3.25 mg kg-1 Pb, 0.55-1.95 mg kg-1 Cu, 2.65-4.02 mg kg-1 Zn, 0.96-1.50 mg kg-1 Cr and 0.85-1.36 mg kg-1 Ni, brinjal accumulated 0.50-1.10 mg kg-1 Cd, 0.80-2.64 mg kg-1 Pb, 0.30-0.46 mg kg-1 Cu, 3.26-3.90 mg kg-1 Zn, 0.30-1.02 mg kg-1 Cr and 0.64-0.86 mg kg-1 Ni, spinach accumulated 0.7-1.88 mg kg-1 Cd, 1.26-3.8 mg kg-1 Pb, 0.90-1.45 mg kg-1Cu, 1.6-6.75 mg kg-1 Zn, 0.65-1.05 mg kg-1 Cr and 0.01-3.80 mg kg-1 Ni, and radish plant plant accumulated 0.22-0.38 mg kg-1 Cd, 0.64-1.24 mg kg-1 Pb, 0.19-1.30 mg kg-1 Cu, 0.56-2.70 mg kg-1 Zn, 0.76-1.25 mg kg-1 Cr and 0.21-2.40 mg kg-1 Ni.The range of Cd concentration in brinjal (0.50-1.10 mg kg-1) recorded in this study was lower than the range (1.10 9.20 g g-1) reported by Sharma et al. (2006). Vegetables (spinach and cabbage), range of Ni concentration was highest in spinach (0.01-3.80 mg kg-1). These determine were lower than the range (5.55 15.00 g g-1) reported by Sharma et al., 2006 and Singh et al., 2010 in spinach from Dinapur area as well as the range (0.2 3.0 mg kg-1) in spinach from waste water irrigated areas of Hyderabad reported by Sridhara Chary et al. (2008). In cabbage concentrations of Pb, Cu, Zn, Cr, Ni and were lower during the present study as compared to those obtained by Sridhara Chary et al. (2008). The present concentration (mg kg-1) of 0.300.03 for Cd, 0.940.10 for Pb, 0.830.18 for Cu and 0.940.09 for Cr in radish were lower than the value obtained for radish collected from a suburban area of Zhengzhou city, Henan Province, China (Liu et al. 2006). Khan et al. (2008) have reported higher concentrations of Cd, Pb, Cu, Cr and Ni and in radish plants grown at waste water irrigated areas of Beijing than the clean water irrigated ones. Among all the heavy metals, Zn concentration (4.260.06) was higher and Cr (0.090.07) was lower in cauliflower. Radwan Sala ma (2006) have also found highest concentration of Zn in vegetables collected from Egyptian markets.The bioaccumulation of Cd in spinach is higher than all the tested vegetable samples and similar result have also observed by Zhuang et al., 2009 in chaina. The bioaccumulation of Pb, Cu, Zn, Cr and Ni were found higher in cabbage, carrot, cauliflower, carrot and radish respectively. The results indicate that the concentrations of heavy metals in all the vegetables below the Indian standard (PFA, 2000) and (WHO/FAO, 2007).Heavy metal transfer instrument ascribable to industrialization and urbanization, the heavy metal concentration of soil has increased worldwide. Soil-to- plant transfer of heavy metal is major pathway of human image to soil contamination (Chi et al, 2004). The high transfer factor from soil to plants indicates a strong accumulation of the particular metals by vegetable crops (Khan et al., 2008). The results indicated that TF values were lower for Cd, Pb, Cu and Cr, and higher TF for Zn and Ni from those. The transfer factor values in soil to plant of studied metals such as Cd, Pb, Cu, Zn, Cr and Ni for various vegetables varied between vegetable plants and locations are shown in table 4. The results revealed that there is large variation in transfer factor of Cd, than other metals in all three locations. The spinach (0.0306) had very high transfer factor for Cd and followed by brinjal (0.0207), cabbage (0.0165), carrot (0.0108), radish (0.0071) and cauliflower (0.0049). Similarly, The cabbage (0.4448), had very high transfer factor for Pb and followed by carrot (0.2376), spinach (0.2187), brinjal (0.0207), cauliflower (0.1672) and radish (0.0988) The carrot (0.2977) had very high transfer factor for Cu and followed by, spinach (0.2642), cauliflower (0.2537), radish (0.1740), cabbage (0.0881) and brinjal (0.0818) The carrot (0.0764) had very high transfer factor for Cr and followed by radish (0.0619), spinach (0.0527), cabbage (0.0454), brinja l (0.0408) and cauliflower (0.0054) for location-III The cauliflower (0.2494) had very high transfer factor for Zn and followed by carrot (0.1991), brinjal (0.1909), cabbage (0.1862), spinach (0.1739) and radish (0.0984) for location-II The spinach (0.7469) had very high transfer factor for Ni and followed by carrot (0.4451), radish (0.4542), brinjal (0.2348), cauliflower (0.0732) and cabbage (0.0335) for location-I. The transfer factor of Cd, Pb, Cu and Cr is more in Location III, similarly, Zn in location II and Ni in location-I. Therefore, vegetable crops growing on polluted site can accumulate high concentrations of trace elements to cause serious health risk to consumers.Risk AssessmentIn order to check the health risk of any toxicity from wastewater, it is necessary to estimate the level of exposure of the heavy metals through food chain. In this studied six vegetables were selected and calculate the health risk assessment in foothold of estimated daily intake of metal (EDIM) and estimated health risk index (EHRI) by considering the intake of metal through vegetables by the human being.Estimated Daily Intake of Metal (EDIM)The daily intake of heavy metals was estimated on the basis of the average usage and concentration of metal in particular vegetable spices. The average concentration of Cd, Pb, Cu, Zn, Cr, Ni and Fe are shown in table 3. establish on the above concentrations, the estimated daily intake of metal (EDIM) for adults and children through food chain were calculated is shown in Table 5. The highest daily intake of metal such as Pb, Zn, Ni, Cu, Cd and Cr were from spinach, cabbage, cauliflower, spinach, carrot, spinach and Carrot respectively grown in domestic wastewater for both adults and children. The results of studied revealed that EDIM signify that the consumption of vegetables grown in domestic wastewater polluted location is high but is free from any risk as the dietary intake of Cd, Pb, Cu, Zn, Cr and Ni in adults is below than the permissible limits (WHO, 1996).Estimated Health Risk Index (EHRI)In order to investigate the estimated health risk index (EHRI) associated with domestic wastewater irrigated soil, it is essential to estimate the level of exposure by quantifying the route of exposure of a heavy metal to the scratch person. The results indicate that the EHRI values were less than one for Cd, Pb, Cu, Zn, Cr and Ni in all tested vegetables consumption. Therefore, the health risks of heavy metals such Cd, Pb, Cu, Zn, Cr and Ni exposure through vegetables was no consequences and generally assumed to be safe. All the estimated dietary intake of Cd, Pb, Cu, Zn, Cr and Ni were far below the tolerable limits. The oral reference dose (RD) for Cd, Pb, Cu, Zn, Cr and Ni are 1.0E-03, 3.5E-03, 4.0E-02, 3.0E-01, 1.5E-00 and 2.0E-02 mg kg -1 day -1, respectively given by US-EPA (2002), IRIS (2003). The results of the study showed that EDIM and EHRI suggest that consumption of vegetable grown in polluted soil irrig ated with domestic wastewater is nearly free of risk. But there are also other sources of metal exposure such as dust inhalation, vehicular exhaust which were not include in this study.ConclusionThe prolonged domestic wastewater irrigation increases heavy metal accumulation in the soil has lead to contamination of food crops in the study area. This study shows that edible vegetables shows significant bioaccumulation of heavy metals in vegetables grown in sewage wastewater irrigation. These vegetables are supplied to local markets and there is possibility of health hazard associated with consumption of these contaminated vegetables over a long period of time. The concentration of all heavy metals in domestic wastewater was found to be higher except Zn from the permissible limits of Indian standards (PFA, 2000) and (WHO/FAO, 2007). The results indicated that higher concentration of metals in soils which is contributed prolonged irrigation by sewage wastewater. If it is continues, the concentrations of metals will accumulate in the soil. Relatively higher amounts of these heavy metal which attributes to the reduction in soil pH to moderately acidic conditions as well increase in organic carbon due to the continuous use of sewage effluents. The concentration of heavy metals in all the vegetables is lesser than Indian standard (PFA, 2000) and (WHO/FAO, 2007). The transfer factor of Cd, Pb, Cu and Cr is more in Location III, similarly, Zn in location II and Ni in location-I. Therefore, vegetable crops growing on polluted site can bio-accumulate high concentrations of trace elements to cause serious health risk to consumers. The highest daily intake of metal such as Pb, Zn, Ni, Cu, Cd and Cr were from consumption of the spinach, cabbage, cauliflower, spinach, carrot, spinach and Carrot respectively grown in domestic wastewater for both adults and children. The results of studied revealed that EDIM and EHRI suggest that the consumption of vegetables grown in domestic wastewater polluted location is high but is free from any risk. Therefore, the health risks from the heavy metals such Cd, Pb, Cu, Zn, Cr and Ni exposure through vegetables was no consequences and generally assumed to be safe.Therefore, in order to reduce risks, plants with lower accumulative nature should be grown. In this scenario the present study significantly indicating the need for proper interposition and disposal of domestic wastewater with low cost and worldwide bankable technology.