In recent decades, significant attention has been paid to heavy metal contamination as a dangerous environmental problem because of the toxicity, abundance, persistence and bioaccumulation of these elements (Chen et al., 2016,) (Islam et al., 2017 and ) (Jin et al., 2019). In general, the contamination state of the environment is evaluated by the total concentration of heavy metals (Kanda et al., 2018). The riverine sediments are considered as the main basins for various pollutants following the largely uncontrolled discharge of contamination resulting from human activities and geogenic processes (Liu et al., 2018). The sediment contamination is an important indicator of environmental variation as a result of anthropogenic influence (Gao et al., 2019). River sediments serve as not only a major sink and carrier of heavy metals but also as potential sources of secondary pollution, which can reflect their contamination level (Tang et al., 2014 and ) (Hsu et al., 2016). The heavy metals are released into the aquatic environments from geogenic and anthropogenic sources. The geogenic sources include chemical leaching of bedrock, water drainage basins and runoff from banks (Raj et al., 2017). The anthropogenic sources of heavy metals pollution in aquatic systems include mining activities, industrial wastes disposal and pesticides use, (Chakravarty & Patgiri, 2009). The heavy metals pollution of sediments is an indicator of the aquatic systems water quality (Zhao et al., 2012). The heavy metal distribution in sediments and pollution levels supplies a base for consideration of sediments treatment methods and evaluation of the potential releasing of heavy metals into water and transport downstream (Nawrot et al., 2020). The vertical and spatial distribution of heavy metals and pollution levels have been evaluated in sediments of many world rivers, such as the Yinma River, China (Guan et al., 2018), the Voghji River, Armenia (Gabrielyan et al., 2018), the Barigui River, Brazil (Machado et al., 2017), the Harazdan River, Armenia (Petrosyan et al., 2019), the Thames River, the UK (Vane et al., 2020), the Yang River, China (Tang et al., 2020), and the Lu Lu River, China (Ye et al., 2020). The spatial distribution of heavy metals in sediments of the Euphrates River in Iraq has been investigated by many authors (Issa & Qanbar, 2016); (Al-Taher et al., 2020); and (Hussain & Al-Jaberi, 2020). The spatial variation of heavy metal concentrations in sediments of the Euphrates River along the studied area between Heet and Ramadi Cities has been studied by (Al-Bassam & Al-Mukhtar, 2008) and (Salah et al., 2012). The aim of the study is to investigate how heavy metals are laterally and vertically distributed in sediments of the given study area of Euphrates River between Heet and Fallujah Cities. This study represents the first attempt to investigate the vertical distribution of heavy metals in the Euphrates River sediments.
