Submit Manuscript | http://medcraveonline.com Introduction The sediments are usually the ultimate sink of heavy metals discharged into the aquatic environments, therefore, analysis of heavy metals (and other contaminants) in the sediments offers a more convenient and more accurate means of detecting and assessing the degree of pollution. 1,2 Sediments serve as the ultimate sink for many contaminants and as a result, they pose the highest risk to the aquatic life as a source of pollution. 3 The sediments are the main repository and source of heavy metals in the marine environment and that they play a major role in the transport and storage of potentially hazardous metals. 4 In addition, heavy metal concentrations in surface sediments can provide historical information on heavy metal inputs at that location, where surface sediments used as environmental indicators to refect the current quality of marine systems for many pollutants. 5 Sediment acts as a sink for metals and the highest concentrations of toxic heavy metals in marine environment are found in sediments. 6‒8 Coastal sediments are important hosts for heavy metal pollution and play an important role in determining the fate and effects of a wide variety of contaminants. 9 Vertical concentration gradientts of heavy metals in sediment cores can provide temporal information about the perturbation in the aquatic environment. 10 The distribution of metals in sediment is very important from the point of view of environmental pollution because sediment concentrates metals from aquatic systems, and represents an appropriate medium to monitor contamination due to sediments are the principal sinks for heavy metals in an aquatic systems. 6,7,11 In spite of the fact that metals occur in the ecosystem naturally by geogenic and lithogenic processes, the heavy metals of anthropogenic origin tend to be bioavailable and then toxic pollutants. 12 Nijenhuis et al. 13 reported that the enrichment of trace elements in marine sediments may, in general, originate from the following sources; super-and subjacent sediments, through diagenesis; suboxic shelf and slope sediments, hydrothermal input; Aeolian input; fuvial runoff; seawater. Under natural condition, the most important inputs of heavy metals to coastal regions are the mechanical weathering of rooks. 14 Urban and industrial activities contribute to the introduction of signifcant amounts of pollutants (among them trace metals) into the marine environment and affect directly the coastal systems where they are quite often deposited. 6,7,15 In some places along the Red Sea coast of Yemen heavy minerals are usually common and represent 50% or more of the beach deposits. 16 These beach deposits are mainly derived from mountainous regions, which drain from the Yemen highlands to the sea through numerous valleys. 8,17-19 The Red Sea environments receive either locally or more widely, a variety of stresses as a result of human activities. The different anthropogenic activities included recreational resorts, urban agglomeration, marine shipping, activities of phosphate industry and fshing ports, as well as limited freshwater and sewage sources. 2,20 The present study was conducted in order to monitor, investigate and Ecological Risk Assessment the accumulation of heavy metals (Cu, Cd, Zn, Ni and Pb) in coastal sediments in the intertidal zones between Al-Haymah and Al-Mokha of south Red Sea Coast Yemen. Material and method The methods section includes study areas, sample collection and lab analysis, assessment of potential ecological risk and statistical analysis. Study area The study area extends from Al-Haymah to south Al-Mokha along Red Sea and covering a distance of about 90 Km along the shore line, Int J Hydro. 2019;3(2):159‒173. 159 ©2019 Al-Edresy et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and build upon your work non-commercially. Ecological risk assessment of heavy metals in coastal sediments between Al-Haymah and Al-Mokha, south red sea,Yemen Volume 3 Issue 2 - 2019 Majed AM Al-Edresy, 1 Saeed O Wasel, 2 Hagib A Al-Hagibi 3 1 Marine Chemistry and Pollution Department, Hodeidah University,Yemen 2 Marine Geology Department, Hodeidah University,Yemen 3 Earth and Environmental Sciences Department, Sana’a University,Yemen Correspondence: Majed AM Al-Edresy, Marine Chemistry and Pollution Department, Faculty of Marine Science and Environment, Hodeidah University,Yemen, Email Received: April 02, 2019 | Published: April 26, 2019 Abstract The area between Al-Haymah and Al-Mokha on the Red Sea of Yemen is a promising region for future tourism development. It is also characterized by population activities, especially fshing in more than one location and there is a commercial port in Al-Mokha. The aim of the present study is to investigate the distribution of heavy metals (Cu, Cd, Zn, Ni and Pb) and Ecological Risk Assessment to assess the contamination levels of the coastal surface sediments. Distribution and ecological risk for Cu, Cd, Zn, Ni and Pb in sediment samples collected from 11 regions (37 stations) in the coasts of Yemen were studied. The results showed that the most of sediments are sand (83.83%), the content of organic matter was low (1.4%) and rich of calcium carbonate (56.1%), while the heavy metals arranged according to their abundance as follows: Zn>Cu>Ni>Pb>Cd. The contamination factor values for heavy metals arranged according to their dangerous as follows: Cd>Cu>Zn>Pb>Ni, and the potential ecological risk index values for heavy metals, according to the order evaluation of pollution in the various regions as follows: Qataba>Al-Mokha>North Al-Mokha>Al-Ruays>Abu-Zahr>South Al-Mokha>Zahari>Al- Khowkhah>Al-Haymah>Yokhtul>Moushij. The present study shows that the coastal sediments in this part of the Red Sea coast of Yemen are not Polluted by heavy metals (Cu, Zn, Ni and Pb), but it heavily polluted by Cd. Keywords: red sea, coastal sediment, heavy metal pollution, contamination factor, potential ecological risk index International Journal of Hydrology Research Article Open Access