CHAPTERONE01.INTRODUCTION Pollution of the naturalecosystem with heavy metals has become a worldwide problem (Premarathna etal. 2010). Scientists are concern about this problem because heavy metalsare non-biodegradable and are highly persistent in the environment(Wickramaratne et al. 2016, and Nazemi, 2012). In Sri Lanka most farmersuse pesticides, herbicides, fertilizers and organic manures beyond the recommendeddoses for their intensive cultivation (Premarathna et al. 2005 and Premarathnaet al.
2010). In those cultivation streams, rivers, tanks, and dug-wellsare the primary sources of water for irrigation. Water sources, soil andvegetables are mostly contaminated with heavy metals by anthropogenicactivities like agricultural practices, transport, industrial activities, wastetreatment and disposal (Biljana et al. 2010). Vegetablesare considered one of the indicators in the environment for estimation of thelevel of metal pollution (Lawal and Andu, 2011). Heavy metal contamination inthe environment is also monitored by measuring their concentrations in soils,water and plants, since for the normal metabolism of the plant life, metals aretaken up from water, air, and soil.
Several studies (Cheraghi, 2009, Lin Jia etal. 2010, Nazemi, 2012, Zarhouny et al. 2015, and Khan et al.2015) have been conducted to investigate the contamination of heavy metals insoil and vegetables.
Furthermore Eslami et al. (2007) studied heavymetals in edible green vegetables grown along the sites of the Zanjanroad Riverin Zanjan, Iran. In Sri Lanka Premarathna et al. (2005) and Arasaretnamand Ebenezer, (2014) studied heavy metal contamination levels in vegetables andsoil. Premarathna et al. (2010) and Kananke et al. (2014) also investigatedheavy metal contamination in green leafy vegetables. Further Wikramaratne etal.
(2016) assessed heavy metal contamination of aquatic vegetablescollected from cultivation sites in Sri Lanka. Thetransfer factor or bio-concentration factor of heavy metals in vegetables hasbeen studied (Yoona, 2006, Anita, 2010, and Khan, 2015) to provide informationon how these metals are transferred to vegetables from soils. Soils areimportant sinks for various pollutants such as pesticides and heavy metals(Premarathna et al. 2010) thus play a significant role in remobilizationof contaminants under favorable conditions. Farmers use chemical and organicfertilizers, and livestock and poultry manure, which contain many impuritiesincluding heavy metals (Premarathna et al. 2005, Premarathna et al.2010, and Lin Jia et al.
2010). Vegetables grown in contaminated soils absorbheavy metals and deposit them on different parts of the vegetables (Nazemi,2012, and Akan, 2013). Heavy metals such as Cu, Zn, Mn, and Fe are essentiallyrequired by crops, but surplus amount of those heavy metal accumulation lead toundesirable effects. Heavy metals such as Pb, Cd and As are toxic even at verylow concentrations in both crops and humans. They can inactivate many importantenzymes resulting in inhibition of photosynthesis, reduction of respiratoryrate and other metabolic processes in crops (Kananke et al.
2014).Consequently in humans their consumption leads to acute and chronic diseasesand many malfunctions (Jarup, 2003 and Hodgson, 2010). The present study evaluated the effects ofdifferent field conditions on Cd, As and Pb content in beetroot (Beta vulgaris L.)which is cultivated in most of the areas in Sri Lanka (Horticultural Crop Research and Development Institute, Department ofAgriculture, Sri Lanka). Both the roots and leaves are consumedas vegetables, which are rich sources of vitamins, minerals, fibres andanti-oxidants (Schick, 2008).
The total production of beetroot in 2005 was22,371 MT from 2,114 ha and 50,172 MT from 2,584 ha in 2015 (Department ofCensus and Statistics, 2017). Asfood safety is a major concern worldwide and there is no any available researchstudies done on heavy metal contamination of beetroot in Sri Lanka, this study wasconducted with the following objectives. 1.1 Objectivesof this study The overallobjective is to evaluate the effects of different field conditions associatedwith cultivation of beetroot on Cd, As and Pb levels: fertilized with chemicalfertilizer and irrigated with ground water (CFGW); fertilized with chemical fertilizerand irrigated with tank water (CFTW); fertilized with chemical fertilizer andirrigated with river water (CFRW); fertilized with organic fertilizer and irrigatedwith ground water (OFGW); cultivated close to a power plant fertilized withchemical fertilizer and irrigated with ground water (PPCFGW).