Methyl Mercury Production in Natural-Collected Sediment With Different Geochemical Parameters

Abstract

Production of methyl mercury (MeHg) has been shown in laboratory experiments using mercuric chloride (HgCl2) compound released into natural-collected sediments with different geochemical conditions. While the HgCl2 concentration was 30 µl of 113 ppm of HgCl2, the geochemical conditions [pH, salinity, total organic content (TOC), sulfur] of sampled sediments were A: 8.20, 0.00 ppt, 1.97%, and 0.92 ppt, respectively; B: 7.90, 2.00 ppt, 4.69%, and 1.98 ppt, respectively; and C: 8.20, 24.00 ppt, 1.32 %, and 90.90 ppt, respectively. A control was set with no HgCl2. Samples and control were incubated in room temperature of 27 ± 1 °C. Observations were done along 9 days with interval of 3 days. While total Hg was measured using mercury analyzer with Cold Vapor-Atomic Absorbtion Spectrophometer (CV-AAS) system, MeHg was measured by using a gas chromatograph with ECD detector after extracted by dithizone-sodium sulfide extraction method. The result shows that MeHg was found in both treatment and control experiments. The concentrations of the MeHg varied according to the geochemical condition of the sampled sediments. Peak production of MeHg occurred on the third day; however, the production was not significantly affected by the incubation time. Optimum production was found inversely related to the pH, in which highest and lowest the pH formed an ineffectively methylated mercury species. The TOC was significantly correlated to the optimum production. Salinity and sulfate contents were found not correlated to the optimum of MeHg production. Keywords: Methyl mercury; methylation process; sediment; biogeochemistry

Mercuric pollution of surface water, superficial sediments, Nile tilapia (Oreochromis nilotica Linnaeus 1758 [Cichlidae]) and yams (Dioscorea alata) in auriferous areas of Namukombe stream, Syanyonja, Busia- Uganda

“…The mean THg content of the sediments in this study is lower than the values registered in other global studies such as 0.265µgg -1 reported by Donkor et al [82] in Pra river (Ghana), 0.7-9.3µgg -1 reported by Ramirez-Requelme et al [83] in Amazon and 0.3-0.9µgg -1 recorded by Feng et al [84] in Shaanxi Province of the Peoples` Republic of China. However, Lasut et al [85] in Indonesia, Pataranawata et al [86] in Thailand, Mohan et al [51] in Nilambur, Kerala-India and Oladipo et al [57] in Manyera river, Nigeria reported lower THg content of sediments of 0.010-0.017, 0.096-0.402, 0.103-0.46, and 0.018µgg -1 respectively which are comparable to the mean THg concentrations recorded in this study. Taylor et al [87] reported that the drainage sediments from upstream of Uvinza on the Malagarasi river (Tanzania) contain THg in the range of 0.17-0.24 µg/kg, which were lower than for sediments from Ilagala with 0.10 to 0.66 mg/kg THg but all higher than the mean THg registered in this study.…”

Kepekaan Cacing Laut Ophryotrocha diadema (Polychaeta: Dorvilleidae) terhadap Cemaran Metil Merkuri (MeHg)

“…Merkuri dapat mengalami proses transformasi menjadi bentuk yang lebih beracun, misalnya melalui proses metilasi yang terjadi di sedimen perairan dengan Hg inorganik diubah menjadi bentuk Hg organik yang umumnya dikenal sebagai metil Hg (MeHg) yang merupakan racun saraf pusat (Ikingura dan Akagi, 1999;Acha et al, 2004, Bishop et al, 2004Yamaguchi et al, 2007;Lasut et al, 2009). Metil Hg dapat diakumulasi oleh organisme perairan, misalnya ikan (Ikingura dan Akagi, 1999), kerang-kerangan (Bergeron et al, 2004), dan organisme lainnya (Lasut et al, 2010).…”