Metal contents of Porites corals from Khang Khao Island, Gulf of Thailand: Anthropogenic input of river runoff into a coral reef from urbanized areas, Bangkok

• Published in: Applied geochemistry 2013-10, Vol.37, p.79-86
• Main Authors: Tanaka, Kentaro, Ohde, Shigeru, Cohen, Michael D., Snidvongs, Anond, Ganmanee, Monthon, McLeod, Cameron W.
• Format: Article
• Language: English
• Subjects: Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Freshwater; Geochemistry; Marine geology; Pollution, environment geology; Porites
• ISSN: 0883-2927; 1872-9134
• DOI: 10.1016/j.apgeochem.2013.07.005

•High V/Ca in corals from the Gulf of Thailand suggested oil pollution since the 1990s.•Decreased Cd/Ca in the corals since 1985 indicated deceasing Cd input in the Gulf.•Pb/Ca in the corals reflected the use history of leaded gasoline in Thailand since 1983. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been used to assess the impact of metal pollution on Porites skeletons taken from the Gulf of Thailand since the 1980s. The collection period coincided with a series of laws enacted by the Thai government to curb environmental pollution. The extent of metal pollution by riverine input, including aerosol deposits, was assessed by comparing the metal/Ca (Me/Ca) ratios in the Thai corals to the ratios of another colony of corals sampled from Rukan-sho, a relatively unpolluted coral reef located in Okinawa, Japan. In this comparison, high riverine inputs of Ba, V, Cd and Pb were observed in the Thai coral samples. Higher V/Ca ratios found in the Thai corals compared to the Rukan-sho coral suggest anthropogenic V inputs due to fuel oil pollution in the Gulf since the late 1990s. The levels of Cd in the coral suggest a gradual decrease in the Gulf in the late 1990s, with a drastic drop in concentration from the 1980s. The historical variation in Pb/Ca ratios recorded in the coral skeletons suggests that exposure to anthropogenic Pb was a result of discharge from urbanized areas from 1984 to 1998, which has been gradually reduced since Thailand prohibited the use of leaded gasoline in the late 1990s.