Assessment of Heavy Metals (As, Cd, Cr, Hg, Ni, Pb) Accumulation in Tissue of Hard Clam (Meretrix casta, Gmelin, 1791) in Mudflat of Laem Phak Bia, the Area Receiving Effluent from Phetchaburi Municipal Wastewater Treatment System, Laem Phak Bia Sub Distr

Abstract

An assessment of heavy metals (As, Cd, Cr, Hg, Ni, Pb) accumulating in hard clam (Meretrix casta, Gmelin, 1791) was examined in clam found in mud flat area of Laem Phak Bia, the area receiving effluent treated wastewater from Phetchaburi Municipal Wastewater Treatment System Laem Phak Bia Sub District, Ban Laem District, Phetchaburi Province. A simple technology based on nature-by-nature purifying processes was used including 1) oxidation ponds 2) plant and grass filtration 3) constructed wetland 4) mangrove forest filtration. Samples were collected during the lowest sea levels in September 2012 (Rainy season) and March 2013 (Dry season). Three sets of clam tissues including the original, boiled and sea-soaked hard clam tissues were analyzed using Inductively Couple Plasma-Mass Spectroscopy (ICP-MS) and Inductively Couple Plasma Optical Emission Spectroscopy (ICP-OES). Statistical results showed no significance amount of heavy metals with p>0.05 among those three sets. The highest value of Arsenic (As), at 0.01468 milligrams/kilograms was found in sea-soaked tissues, whereas the lowest value of Lead (Hg), at 0.00023 milligrams/kilograms was found in original tissue. The concentration of heavy metals in tissues of calm living in mud area of Lam Phak Bia is at standard level which is safe for eating.