Wavelength Dispersive XRF Study of Heavy Elements in Soil in Cancer Hit Villages of Malwa region of Punjab, India

Heavy metals in the soil of 13 villages of Bathinda district, Punjab, India, were measured using wavelength dispersion X-ray fluorescence technique (WDXRF). 29 elements for which these samples were analyzed are U, Th , 40K, Pb, La, Ba, Cs, Ce,, Sn, Sb, As, Cr, Zn, Cu, Co, Sr, Zr, Sc, V, Ni, Rb, Mo,Ga, Nb, Y, Fe2O3, CaO, MnO and TiO2. Radioactive substances like U and Th are quite low. Alkaline elements like Ca, Ba, Sr are quite high and may be acting as catalysts to low level radioactive elements. As, Fe, Co, Ni, Zr, Cr, Zn too are probably due to proximity of a thermal power plant at Bathinda and use of pesticides and fungicides for plantation.


INTRODUCTION
During the last 10-15 years, many reports appeared in the media regarding high radioactivity in the soil and water of Malwa region. Many researchers undertook measurements in water and soil to determine the quantity of uranium, thorium and potassium [1][2][3][4] . A good correlation was obtained between uranium concentration in soil and indoor radon in dwellings by Mehra et al., 1 . Work on soil samples from Malwa region was also reported by Mehra et al.,2 . Uranium, thorium and K-40 content were found within safety limits. Recently radioactive content in 498 water samples from the region reported by Bajwa et al., 3 . 338 out of 498 samples had uranium concentration higher than recommended safe limit of 0.03 ppm while 216 samples exceeded the threshold of 0.06 ppm recommended by AERB, DAE, India 5 . Hearing a public interest petition, filed by Brijinder Singh Loomba the Punjab and Haryana High Court Chandigarh assigned the job of measuring radioactivity of Malwa region to BARC, Bombay 6 . The petition was filed after a UKbased clinical toxicologist Carin Smit came out with a startling revelation that traces of uranium and other heavy metals were found in the hair samples of children and adults in Faridkot district of Punjab which has no uranium mines. The high concentration of radioactive material was quite baffling for scientists and environmentalists. The BARC report claimed that the high salinity of water in the Malwa region may be acting as a catalyst for uranium toxicity. Otherwise they did not find any higher amounts of uranium or thorium in Malwa region. Still many reports are appearing in the media regarding cases of cancer in the region. In view of all this we have decided to study the metal content in the soils of Talwandi Sabo subdivision of Bathinda District using WDXRF technique to find whether heavy elements or other toxic elements are responsible for any cancer cases.
Soils and sediments have a complex composition and their multi-element chemical composition is of interest in several fields, mostly in geochemical surveys for economical and environmental applications 7 . Abnormal occurrences of heavy elements in rocks and soils and in monazite sands have been identified in several regions of the world. The most important sources of heavy metals in the environment are the anthropogenic activities such as mining, smelting procedures, steel and iron industry, chemical industry, traffic, agriculture as well as domestic activities [8][9][10] . The heavy metals from these sources are dispersed in the environment and they contaminate soil, water and air. Directly or indirectly through plants, water and food they get into the human and animal bodies 11 . The presence of heavy metals in soil can affect the quality of food, groundwater, micro-organism activity and plant growth etc. [12][13][14] . Evaluation of the threat of accumulation of toxic metals in soils is difficult and depends upon many factors. The availability of these metals to crops can be explained by knowing their distribution in the soil profile and the chemical forms in which they occur. Several metals, such as As, Pb, U, Th, Cd, Cu etc. accumulate in the surface soil horizon due to their low mobility and strong association with organic matter. In this current work the pollutants which found in high amount are Co, CaO, Pb, As, Ni, Y, Rb and Zr. Such elements are generally found in cancerous tissues and responsible for cancer related health issues. The aim of the present study is to find out the concentration of heavy elements in the soils of cancer hit villages of Malwa region of Punjab State.

geography of selected area
Bathinda district is situated in the northwestern region of India and is a part of the Indo-Gang tic alluvial plains. The exact cartographic co-ordinates of Bathinda are 30.20°N 74.95°E with an average elevation of 660 ft (201 meters). The study area of 13 villages of Talwandi Sabo is 30km from the head quarters of the district towards South East (Fig. 1). Its climate corresponds to high variation between summer and winter temperatures namely 45 0 C to 15 0 C. Average annual rainfall of Bathinda is in the range of 20 mm to 40 mm.

Soil sample Characteristics
To get the large variations, the soil samples of different soil types were selected. Most of the soils in the study area are dry contain stones and pebbles.

Sample Collection and Methodology
Soil samples were collected from 39 locations from various villages selected with 3 samples from each village on random basis. Each sample was taken from a depth of 70-80 cm at some selected points within the study area. In order to cover a large area and to observe a significant local spatial variation in terrestrial radioactivity, sampling points were at a minimum distance of 2 km from each other. In order to get uniform and representative samples they were dried, sieved to remove stones, pebbles grass roots and straws and then crushed to pass through a 150 micron mesh sieve to homogenize the contents. Then they were packed in plastic bags, which were well sealed. The weight of the soil sample in each bag was kept constant on 20 g. All the 39 samples were analyzed to detect the elements of interest using wavelength dispersion X-ray florescence in SAIF, Panjab University Chandigarh. A diagram of a WD system is shown in Figure 2.

RESULTS AND DISCUSSION
Although Uranium and Thorium in the measured soil samples were quite low to cause any damage yet elements like CaO, Co, Zr, Rb are found in higher amounts. CaO, Co, Zr were noted much higher than their permissible values (Table 3) in all the villages (except one location of Kaurena village having CaO concentration of 9773 ppm). 74%

Fig. 2. Schematic diagram of a wavelength-dispersive X-ray spectrometer
This instrument operates according to the principle of Bragg diffraction of a collimated X-ray beam. A detector is angularly scanned relative to the analyzing crystal and registers the spectrum. A great advantage of XRF techniques compared to wet chemical procedures is that the multi-elemental analysis can be directly carried out on solid samples. This avoids the tedious and laborious wet digestion steps and the possible analyte losses and sample contamination as well as a considerable decrease in analysis time. The higher detection limits compared to spectroscopic techniques the precision and accuracy obtained educing XRF methods are good enough for various environmental studies purposes 15  Major and many trace elements can be determined with very good precision and accuracy 7 . In the present study WD-XRF (wavelength dispersive X-ray fluorescence) Model: S8 TIGER, made of Bruker, Germany, has been used for the soil sample analysis. Soil sample and binder were grinded together to make homogenized fine powder so that particle size became less than 50 µm. Sample quantity was taken as 9 g. The binder tablet amount was 2.7 g, which made the total weight equal to 11.7 g. A pellet was made of 10 g of total sample (11.7g) of villages have high value of Rb (Table 3). Among these the elements that cause alkalinity such as Ca, Rb are quite high. These may be due to coal fired TPP (Tharmal Power Plant) at Bathinda which is not very far off from the invested area. When coal or lignite rich in limestone, produce ash having calcium oxide, it (Lime stone (CaO)) easily diffuses in water bodies and make calcium hydroxide Ca(OH) 2 and transformed through rain water to canals or agriculture water systems and ultimately reach into the soils 16 . In India, the ash content in the coal utilized in power production is about 30 to 40%, which is rather more than the other developed nations. Higher values of coal fly ash resulting in high damage to the plants as well as machines. All the heavy elements commonly found in the coal fly ash are poisonous in nature 17 .

Fertilizers
For healthy plant growth not only macronutrients, but also some micronutrients (such as Co, Cu, Fe, Mn, Ni, and Zn) are also required in limited amounts. But if the range of theses essential heavy elements crossed the safety limits, then the soil becomes polluted. Large quantities of fertilizers are regularly added to soils in intensive farming systems to provide adequate N, P, and K for crop growth. In the study area generally Urea containing N, Di-ammonium Phosphate (containing N, P), Zinc phosphate (containing Z, P) etc. are used. The compounds used to supply these elements contain trace amounts of heavy metals (e.g., Cd and Pb) as impurities, which after continued fertilizer, application may significantly increase their content in the soil 21 . These toxic elements not only affect the grown plants and crops, but also get transferred to human bodies through food items. In the present study it has been found that micronutrients like Zn in Manuana and Ram Nagar, Co, Ni in all villages and macro nutrient K are quite high in amounts in Maur Chart, Burj, Joge Wala and Gatwali villages, as compared to the permissible values.

Pesticides and weedicides
The chemicals used as insecticides and fungicides are based on compounds which contain Cu, Hg, Mn, Pb, or Zn. Examples of such pesticides are copper-containing fungicidal sprays such as Bordeaux mixture (copper sulphate) and copper oxychloride 22 . Formulations of Cu, Cr, and As (CCA) derelict sites where soil concentrations of these elements greatly exceed background concentrations. Compared with fertilizers, the usage of these substances is more localized, being restrained to particular locations and plantation 23 . In the current work, Zn in Manuana and Ram Nagar, Cu in Gehlawal and Shekhpura and Pb in all villages are far more than their permissible values (Table  3) showing that pesticides and weedicides may influence the quality of soils.

Radio nuclides
Environmental radio nuclides with varying fractions can enter the atmosphere in the form of aerosols or fine dust particles that may be deposited directly on growing vegetation or be inhaled directly by humans and other animals. The human body absorbs these radio nuclides by two routes: inhalation and through food and water. The heavy (or transition) metal elements make up a large part of the periodic table and include some of the most toxic agents known, like mercury and cadmium). In the present case, radio nuclides like U and Th were much below the safety limits as shown in the Table 3. K-40 is quite high in one of the locations in Maur Chart, Burj Jage Wala and Gatwali villages, but overall it is below the permissible values. It shows that radio nuclides are not causing much effect in this region.

Correlation
The Pearson Correlation Program is used to find correlations among the elements found in soil analysis (Table 4) Table 4. These indicate that if one of the element in a given pair is elevated the amount of other decreases.    (Table 3). • Co, Cao, Pb, As, Ni and Y are unusually higher in amounts and might be responsible for routine cancer diseases.

•
Alkaline elements such as Ca, Rb and Zr are very high, particularly Calcium which has been found in higher content in cancerous tissue usually.

•
The basic sources of pollutants (Co, CaO, Pb, As, Ni, Y, Rb and Zr) which are found in extra amount than their permissible limits (Table 3) for this region are may be the coal fired TPP (Tharmal Power Plant) at Bathinda (nearby the studied area) and pesticides, weedicides and fungicides used for agricultural purposes.
To sum up radioactive elements like uranium, thorium and potassium (K-40) are low in content to cause any cancers. Excess of alkalinity causing elements, may be acting as a catalyst for such radioactive elements to be harmful 6 . Hence excess of alkalinity might be the main reason for tumor growth and cancer scare.