Next Article in Journal
Reducing Food Poverty and Vulnerability among the Rural Elderly with Chronic Diseases: The Role of the New Rural Pension Scheme in China
Next Article in Special Issue
Solid Waste Management Solutions for a Rapidly Urbanizing Area in Thailand: Recommendations Based on Stakeholder Input
Previous Article in Journal
Cardiovascular Health of Construction Workers in Hong Kong: A Cross-Sectional Study
Previous Article in Special Issue
Public Awareness of Remanufactured Products in Yangtze River Delta of China: Present Status, Problems and Recommendations
Open AccessArticle

Vertical Distribution of Total Mercury and Mercury Methylation in a Landfill Site in Japan

1
Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, C-kluster, Kyotodaigakukatsura, Nishikyo-ku, Kyoto 6158540, Japan
2
Graduate School of Global Environmental Studies, Kyoto University, C-kluster, Kyotodaigakukatsura, Nishikyo-ku, Kyoto 6158540, Japan
3
National Institute for Minamata Disease, 4058-18 Hama, Minamata-City, Kumamoto 8670008, Japan
4
Environmental Protection Center, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 8140180, Japan
*
Author to whom correspondence should be addressed.
Int. J. Environ. Res. Public Health 2018, 15(6), 1252; https://doi.org/10.3390/ijerph15061252
Received: 15 May 2018 / Revised: 5 June 2018 / Accepted: 8 June 2018 / Published: 13 June 2018
(This article belongs to the Special Issue Sustainable Management of Waste)
Mercury is a neurotoxin, with certain organic forms of the element being particularly harmful to humans. The Minamata Convention was adopted to reduce the intentional use and emission of mercury. Because mercury is an element, it cannot be decomposed. Mercury-containing products and mercury used for various processes will eventually enter the waste stream, and landfill sites will become a mercury sink. While landfill sites can be a source of mercury pollution, the behavior of mercury in solid waste within a landfill site is still not fully understood. The purpose of this study was to determine the depth profile of mercury, the levels of methyl mercury (MeHg), and the factors controlling methylation in an old landfill site that received waste for over 30 years. Three sampling cores were selected, and boring sampling was conducted to a maximum depth of 18 m, which reached the bottom layer of the landfill. Total mercury (THg) and MeHg were measured in the samples to determine the characteristics of mercury at different depths. Bacterial species were identified by 16S rRNA amplification and sequencing, because the methylation process is promoted by a series of genes. It was found that the THg concentration was 19–975 ng/g, with a geometric mean of 298 ng/g, which was slightly less than the 400 ng/g concentration recorded 30 years previously. In some samples, MeHg accounted for up to 15–20% of THg, which is far greater than the general level in soils and sediments, although the source of MeHg was unclear. The genetic data indicated that hgcA was present mostly in the upper and lower layers of the three cores, merA was almost as much as hgcA, while the level of merB was hundreds of times less than those of the other two genes. A significant correlation was found between THg and MeHg, as well as between MeHg and MeHg/THg. In addition, a negative correlation was found between THg and merA. The coexistence of the three genes indicated that both methylation and demethylation processes could occur, but the lack of merB was a barrier for demethylation. View Full-Text
Keywords: mercury; landfill; core sampling; hgcA; merA; merB mercury; landfill; core sampling; hgcA; merA; merB
Show Figures

Figure 1

MDPI and ACS Style

Yang, J.; Takaoka, M.; Sano, A.; Matsuyama, A.; Yanase, R. Vertical Distribution of Total Mercury and Mercury Methylation in a Landfill Site in Japan. Int. J. Environ. Res. Public Health 2018, 15, 1252.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map

1
Back to TopTop