CHAPTER and soil. Premarathna et al. (2010) and

CHAPTER
ONE

01.
INTRODUCTION

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Pollution of the natural
ecosystem with heavy metals has become a worldwide problem (Premarathna et
al. 2010). Scientists are concern about this problem because heavy metals
are non-biodegradable and are highly persistent in the environment
(Wickramaratne et al. 2016, and Nazemi, 2012). In Sri Lanka most farmers
use pesticides, herbicides, fertilizers and organic manures beyond the recommended
doses for their intensive cultivation (Premarathna et al. 2005 and Premarathna
et al. 2010). In those cultivation streams, rivers, tanks, and dug-wells
are the primary sources of water for irrigation. Water sources, soil and
vegetables are mostly contaminated with heavy metals by anthropogenic
activities like agricultural practices, transport, industrial activities, waste
treatment and disposal (Biljana et al. 2010).

 

Vegetables
are considered one of the indicators in the environment for estimation of the
level of metal pollution (Lawal and Andu, 2011). Heavy metal contamination in
the environment is also monitored by measuring their concentrations in soils,
water and plants, since for the normal metabolism of the plant life, metals are
taken up from water, air, and soil. Several studies (Cheraghi, 2009, Lin Jia et
al. 2010, Nazemi, 2012, Zarhouny et al. 2015, and Khan et al.
2015) have been conducted to investigate the contamination of heavy metals in
soil and vegetables. Furthermore Eslami et al. (2007) studied heavy
metals in edible green vegetables grown along the sites of the Zanjanroad River
in Zanjan, Iran. In Sri Lanka Premarathna et al. (2005) and Arasaretnam
and Ebenezer, (2014) studied heavy metal contamination levels in vegetables and
soil. Premarathna et al. (2010) and Kananke et al. (2014) also investigated
heavy metal contamination in green leafy vegetables. Further Wikramaratne et
al. (2016) assessed heavy metal contamination of aquatic vegetables
collected from cultivation sites in Sri Lanka.

 

The
transfer factor or bio-concentration factor of heavy metals in vegetables has
been studied (Yoona, 2006, Anita, 2010, and Khan, 2015) to provide information
on how these metals are transferred to vegetables from soils. Soils are
important sinks for various pollutants such as pesticides and heavy metals
(Premarathna et al. 2010) thus play a significant role in remobilization
of contaminants under favorable conditions. Farmers use chemical and organic
fertilizers, and livestock and poultry manure, which contain many impurities
including heavy metals (Premarathna et al. 2005, Premarathna et al.
2010, and Lin Jia et al. 2010). Vegetables grown in contaminated soils absorb
heavy 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 essentially
required by crops, but surplus amount of those heavy metal accumulation lead to
undesirable effects. Heavy metals such as Pb, Cd and As are toxic even at very
low concentrations in both crops and humans. They can inactivate many important
enzymes resulting in inhibition of photosynthesis, reduction of respiratory
rate and other metabolic processes in crops (Kananke et al. 2014).
Consequently in humans their consumption leads to acute and chronic diseases
and many malfunctions (Jarup, 2003 and Hodgson, 2010).

 

The present study evaluated the effects of
different 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 of
Agriculture, Sri Lanka). Both the roots and leaves are consumed
as vegetables, which are rich sources of vitamins, minerals, fibres and
anti-oxidants (Schick, 2008). The total production of beetroot in 2005 was
22,371 MT from 2,114 ha and 50,172 MT from 2,584 ha in 2015 (Department of
Census and Statistics, 2017).

 

As
food safety is a major concern worldwide and there is no any available research
studies done on heavy metal contamination of beetroot in Sri Lanka, this study was
conducted with the following objectives.

 

1.1  Objectives
of this study

 

The overall
objective is to evaluate the effects of different field conditions associated
with cultivation of beetroot on Cd, As and Pb levels: fertilized with chemical
fertilizer and irrigated with ground water (CFGW); fertilized with chemical fertilizer
and irrigated with tank water (CFTW); fertilized with chemical fertilizer and
irrigated with river water (CFRW); fertilized with organic fertilizer and irrigated
with ground water (OFGW); cultivated close to a power plant fertilized with
chemical fertilizer and irrigated with ground water (PPCFGW).

 

 

 

 

 

 

 

 

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