Decline in heavy metal contamination in marine sediments in Jakarta Bay, Indonesia due to increasing environmental regulations Takahiro Hosono a, * , Chih-Chieh Su b , Robert Delinom c , Yu Umezawa d , Tomoyo Toyota e, f , Shinji Kaneko g , Makoto Taniguchi e a Priority Organization for Innovation and Excellence, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan b Institute of Oceanography, National Taiwan University, No.1, Sec. 4, Roosevelt Road, Taipei, Taiwan c Research Centre for Geotechnology, Indonesia Institute of Science, Jln. Cisitu Sangkuriang, Bandung 40135, Indonesia d Faculty of Fisheries, Nagasaki University,1-14 Bunkyo-machi, Nagasaki 852-8521, Japan e Research Institute for Humanity and Nature (RIHN), 457-4 Motoyama Kamigamo, Kita-ku, Kyoto 603-8047, Japan f Japan International Cooperation Agency (JICA) Research Institute,10-5 Ichigaya Honmuracho, Shinjuku-ku, Tokyo 162-8433, Japan g Graduate School for International Development and Cooperation, Hiroshima University, 1-5-1 Kagamiyama, Higashi-Hiroshima 739-8529, Japan article info Article history: Received 5 August 2010 Accepted 14 January 2011 Available online 28 January 2011 Keywords: Jakarta Bay sediments heavy metal contamination 210 Pb dating lead isotope ratio abstract The 210 Pb geochronology, heavy metal concentrations (Zn, Cu, and Pb), and stable Pb isotope ratios ( 206 Pb/ 207 Pb) of three sediment cores collected from Jakarta Bay were analyzed to decipher the history of heavy metal contamination in the period 1900e2006. The chemical and isotopic analyses clearly suggest that anthropogenic metal accumulation in the sediments began in the 1920s and increased greatly from the 1970s until the end of the 1990s. From the end of the 1990s to 2006, accumulation rates were constant or decreased for Zn and Pb near the coastal industrialized area. Comparison of economic data and sociological information suggests that the decline in the concentrations of heavy metals could be attributed to the stricter environmental regulations which were enforced at the end of 1990s. However, metal contamination is currently still an important cause of concern in dealing with environmental preservation and protection in Jakarta Bay. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Heavy metal contamination in coastal marine environments is becoming an increasingly serious threat in Asian coastal megacities which are undergoing rapid economic growth and industrialization (Jiang et al., 2001). The toxic metals in seawater and marine sedi- ments are incorporated into the aquatic food webs through primary producers and detritivores (Chapman et al., 1998), and then bio- magnified at higher trophic levels (Atwell et al., 1998; Wang, 2002; Viana et al., 2005). This is potentially damaging to mammals, other vertebrates and human health (Scheuhammer et al., 2007). To develop pollution control strategies for coastal environments, the current contamination status needs to be assessed within the framework of the long-term contamination history. Coastal marine sediments commonly act as a sink for river- borne metals derived from weathering of watershed geology (natural sources) and from pollution sources, such as domestic wastewaters, urban runoff, and industrial effluents (Callender, 2005). Heavy metals deposited in sediments are not removed by biogenic processes, so metal profiles in sediment cores have been used to reconstruct the pollution histories of estuaries, coasts, and bays, in combination with radioisotope chronologies such as 210 Pb and 137 Cs dating (Church et al., 2006; Mil-Homens et al., 2006; Cantwell et al., 2007; Irabien et al., 2008). In addition, stable Pb isotope ratios (i.e. 206 Pb/ 207 Pb) have frequently been used as valu- able tracers for identifying source(s) of anthropogenic Pb in core sediments (Hirao et al., 1986; Hung and Hsu, 2004; Ip et al., 2004, 2007; Tang et al., 2008; Komárek et al., 2008; Xu et al., 2009). Quantitative studies using the above techniques have docu- mented the decline of heavy metal contamination due to the enforcement of environmental regulations in Japanese metropol- itan bays such as Tokyo (Hirao et al., 1986), Osaka, and Hiroshima Bay (Hoshika et al., 1991). After the 1990s, similar studies have been conducted for other locations in Asia, for instance Manila Bay in the Philippines (Prudente et al., 1994), Jakarta Bay in Indonesia * Corresponding author. E-mail addresses: hosono@kumamoto-u.ac.jp (T. Hosono), donccsu@ntu.edu.tw (C.-C. Su), rm.delinom@geotek.or.id (R. Delinom), umezawa@nagasaki-u.ac.jp (Y. Umezawa), Toyota.Tomoyo@jica.go.jp (T. Toyota), kshinji@hiroshima-u.ac.jp (S. Kaneko), makoto@chikyu.ac.jp (M. Taniguchi). Contents lists available at ScienceDirect Estuarine, Coastal and Shelf Science journal homepage: www.elsevier.com/locate/ecss 0272-7714/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.ecss.2011.01.010 Estuarine, Coastal and Shelf Science 92 (2011) 297e306