Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul Baseline Bioavailable trace metals and their ecological risks in the tourist beaches of the Southeast coast of India S. Krishnakumar a, ⁎ , A. Vidyasakar b , S. Anbalagan c , Prince S. Godson d , K. Kasilingam a , P. Parthasarathy e , D. Pradhap a , P. Saravanan a , S. Hariharan f , A. Rajkumar a , K. Neelavannan c , N.S. Magesh g a Department of Geology, University of Madras, Guindy Campus, Chennai 600025, India b Department of Geology, Periyar University PG Extension Centre, Dharmapuri 636701, India c Institute for Ocean Management, Anna University, Chennai 600025, India d Department of Environmental Sciences, University of Kerala, Thiruvananthapuram 695581, India e Department of Geology, A.V.S College of Arts and Science, Salem 636 106, India f Department of Geology, Central University of Karnataka, Kadaganchi, Karnataka 585367, India g National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Headland Sada, Vasco-da-Gama, Goa 403 804, India ARTICLE INFO Keywords: Acid Leachable Trace Metals (ALTMs) Beach sediments Urban tourist beaches Southeast coast of India ABSTRACT The concentration of Acid Leachable Trace Metals (ALTMs) was assessed in urbanized tourist beaches (96 samples from Marina beach, 34 samples from Edward Elliot's beach, and 28 samples from Silver beach) of southeast coast of India. The concentration of metals accumulated in the beach sediment was less than the Upper Continental Crust (UCC) background reference values. The mean enrichment of ALTMs in the studied urban tourist beaches showed the following descending order: Marina beach – Cr > Pb > Ni > Zn > Cu > Mn > Co; Edward Elliot's beach – Cr > Pb > Ni > Mn > Co > Zn > Cu; Silver beach – Cr > Pb > Ni > Co > Mn > Cu > Zn.The ALTMs such as Fe, Mn, Co, Cu, and Zn were probably derived from natural weathering and mild anthropogenic influences whereas other metals were derived from anthropogenic induced factors. Heavy metals in beach sediments can be derived from natural weathering processes and anthropogenic sources (Bartoli et al., 2012). The nature of the sediments, grain size, properties of adsorbed particles, and metal characteristics control the mobility and accumulation of metals in sediments (Bastami et al., 2014). The rapid urbanization and industrialization close to coastal aquatic regions are the chief sources of metal pollutants (Gutiérrez-Mosquera et al., 2018). During the coastal/ estuarine mixing process, the dissolved metals are transported and ac- cumulated quickly by the water column and are adsorbed by the par- ticulate matter through various physico-chemical processes. They keep moving from the water column to the sediments due to change in pH and salinity variations (Boyle et al., 1977). Besides, the environmental condition also plays a strong influential role in the accumulation and release of metals because they are often associated with organic matter, absorbed on FeeMn hydroxides, or precipitated as hydroxides, sulfides, and carbonates (Forstner, 1983; Jayaprakash et al., 2014). The libera- tion of acid leachable trace metal (ALTM) fraction from the sediments depends on the association of elements with particles, on binding strength, and on water properties such as pH, redox potential, salinity, and dissolved metal species which are in touch with the solid phase (Filgueiras, 2004). Previous researches have proved that the acid leachable technique is effectively adopted as the fundamental method to determine metal concentrations for evaluating the potential en- vironmental and ecotoxicological impacts in beach sediments (Jayaprakash et al., 2008; Ayyamperumal et al., 2006; Jonathan et al., 2010; Nagarajan et al., 2014; Gutiérrez-Mosquera et al., 2018). Various acid leaching techniques have been followed to study the sediment accumulated elemental concentration such as use of 0.5 N HCl (Agemian and Chau, 1976); sequential extraction technique (Tessier et al., 1979); use of different combinations of HNO 3 , HCl, HClO 4, and HF (Barau, 1982); use of HNO 3 -HCl combination (USEPA, 1992); and single extraction by HNO 3 (Gismera et al., 2004). The study area is located on the southeast coast of the Indian Peninsula and forms a part of the Coromandel Coast, Bay of Bengal. It is the second-longest coastline in the country, and the coastal stretch extends about 1076 km from Pazhaverkadu near Chennai to Ezhudesam https://doi.org/10.1016/j.marpolbul.2020.111562 Received 24 May 2020; Received in revised form 31 July 2020; Accepted 9 August 2020 ⁎ Corresponding author. E-mail addresses: coralkrishna@gmail.com (S. Krishnakumar), nsmagesh@ncpor.res.in (N.S. Magesh). Marine Pollution Bulletin 160 (2020) 111562 0025-326X/ © 2020 Elsevier Ltd. All rights reserved. T