Metal pollution status and health risk assessment of beach sediments along the Mersin coast, Turkey

Heavy metal contamination in the soils and sediments is a worldwide problem due to its ubiquity, trace-level toxicity, bioaccumulation and persistence (Buccolieri et al. 2004; Buccolieri et al. 2006; El-Sorogy et al. 2016; Jia et al. 2018). Heavy metals enter the human body through the gastrointestinal tract, skin and via the air (Pan et al. 2019; Witkowska et al. 2021). Excessive intake of heavy metals in the human body can cause many health problems such as neurological, cardiovascular, and chronic kidney diseases, tumours, and even cancers (Pan et al. 2019; Al-Kahtany & El-Sorogy 2023 and references therein).

Beaches are one of the most important assets for coastal tourism in Turkey (Birdir et al. 2013). The Mersin province is located on the eastern Mediterranean coast of Turkey (latitude 36°48’0”N, longitude 34°38’0”E) with a surface area of 15,853 km² and it has 321 km coastline and flatland along the coast (Figure 1) (Birdir et al. 2013; Limoncu et al. 2020). According to census data, Mersin’s population was 1,891,145 in 2021. The Mersin coastline has experienced rapid development and one of the most distinctive features of the Mersin city is its bathing facilities and beaches (Ünal & Birdir 2007; Birdir et al. 2013). Many studies have been carried out to determine heavy metal contamination in beach sediments along the northeastern Mediterranean coast using multiple indices such as enrichment factor (Çevik 2009; Yalcın & İlhan 2008; Yalcın 2009; Yalcın et al. 2013; Yalcın et al. 2020). However, no study has been performed to determine the potential health risk assessment of beach sediments along the Mersin coast located on the northeastern Mediterranean Sea that has assets for coastal tourism in Turkey.

Figure 1

The main objective of this study is, therefore, to determine metal pollution status and health risk posed by beach sediments for adults and children along the Mersin Coast used by large numbers for coastal tourism.

In this study, ecological and health risk assessments of beach sediments along the economically important Mersin coast were determined and presented in Figure 2. Previous studies showed that heavy metal concentrations in beach sediments along the Mersin coast displayed pronounced spatial variability (Table 1). It is well known that natural contamination and anthropogenic impacts affected the distributions of metals in the beach sediments along the Mersin coast. The peak values were consistently recorded in the beach sediments of the Mersin coast due to natural contamination as basic/ultrabasic rocks outcropped in the region (Yalcın et al. 2013) and weathering/erosion of these rocks (Tuncel et al. 2007). Anthropogenic disturbances also increased the metal levels in beach sediments along the Mersin coast (Alp et al. 2012).

Figure 2

Ecological risk assessment of heavy metals showed that the beach sediments are not polluted by the metals Cu, Pb and Zn for the all studied coasts (Figure 2). However, Cd, Cr and Ni pollution is pronounced in the Kızkalesi, Susanoğlu and Taşucu beach sediment (Table 5). The sources of anthropogenic metal pollution in the coastal regions are generally contaminated rivers, estuaries, domestic and industrial wastewater inputs, vehicle emissions, and agricultural runoff (Ip et al. 2007; Yalcın & İlhan 2008; Saher & Siddiqui 2016; Nour & El-Sorogy 2020; Akçay & Özbay 2022). Study findings indicated that the beach sediments were polluted by the metals Cr and Ni in the Mersin province due probably to contaminated rivers and wastewater inputs originated from agricultural activities and discharge from mines, also reported by the studies by Çevik et al. (2009) and Özbay et al. (2013). Coastal surface sediments in the Mersin inner Bay were also affected by Cr pollution (Akçay & Özbay 2022). Pearson’s correlation indicated strong and positive correlations among both ecological and health risk indices. Furthermore, the correlations between ecological and health risk indices showed that there are strong and positive correlations between Igeo and values of HI and TCR, and between CF and HI values (Figure 3). These correlations strongly suggest that the metal pollution in the coastal beach sediments caused both ecological and health risk in the Mersin Province.

Figure 3

One of the most distinctive features of Mersin city is its bathing facilities and beaches, which are an asset for coastal tourism in Turkey (Ünal & Birdir 2007; Birdir et al. 2013). Mersin province is, therefore, famous for the presence of tourist resorts, marine sports and marine recreational activities. It is critical to assess the health risk posed by beach sediments along the Mersin coast. Some heavy metals can cause health problems such as Cd, Zn, Pb and Hg (Sarkar et al. 2016; Nour et al. 2022). Health risk assessment of beach sediments suggested carcinogenic risk for the adults and children inhabiting the Mersin province from carcinogenic Cr, Ni and Cu (Figure 2). Health risk assessment of beach sediments from different coastal areas reported higher HI values for children than for adults (Alharbi et al. 2022; Abbasi et al. 2022; Nour et al. 2022; Al-Kahtany & El-Sorogy 2023; Al-Kahtany et al. 2023). However, the potential health risk assessment of these regions differs in terms of the heavy metals and the contamination levels. Low TCR values in beach sediments from the Red Sea and Gulf of Aqaba (Nour et al. 2022), along Ras Abu Ali Island, Saudi Arabia (Al-Kahtany & El-Sorogy 2023) and along the southern Al-Khobar coast, Saudi Arabia (Al-Kahtany et al. 2023) indicated no significant health hazards for adults and children. On the other hand, high TCR values calculated in the urban surface soils of Mediterranean Sea region, on Cyprus, showed a high risk for the adults and children from carcinogenic Cr and Ni (Abbasi et al. 2022). The results of this study were in agreement with the study by Abbasi et al. (2022) also conducted in the eastern Mediterranean suggesting an apparent potential health hazard from carcinogenic Cr and Ni.

In this study, the ecological and health risk posed by beach sediments along the Mersin coast was determined. The study findings indicated apparent Cd, Cr and Ni pollution in the Kızkalesi, Susanoğlu and Taşucu beach sediments due to natural and anthropogenic disturbances. In the studied sites, the calculated HI values were consistently higher for children compared to those for adults, suggesting that children were at higher risk. The high TCR values indicated a high carcinogenic risk for adults and children inhabiting Mersin province from carcinogenic Cr and Ni. Moreover, the studied coasts pose additional health risks for children from carcinogenic Cu. Our initial health risk assessment of beach sediments along the Mersin coast will provide critical information for decision-makers to reduce metal contamination of the ecosystem and public health in the Mersin province, an important asset for coastal tourism in Turkey. In order to manage and assess the potential risk of polluted beach sediments, monitoring studies should be carried out.