### 9. 英文概要

研究課題名 = Appropriate Management of the Cyclical Use of Hazardous Metals such as Mercury

研究代表者名及び所属 = Masaki Takaoka (Kyoto University)

分担研究者名及び所属＝Akiko Kida(Ehime University), Hiroshi Moritomi (Gifu University), Fumitake Takahashi(Tokyo Institute of Technology), Misuzu Asari (Kyoto University), Masahiro Oguchi (National Institute for Environmental Studies)

要旨= International programs focused on the reduction of mercury use are ongoing. Lead and cadmium are also candidate substances for international regulation based on a preventative approach.

The purpose of this study was to collect basic scientific information on appropriate management of the cyclical use of hazardous metals such as mercury and establish an appropriate management method. We investigated the following research themes: estimation of recovered mercury and increased recovery of mercury from products/wastes with intentionally added mercury; development of easy-to-use toolkit for mercury and lead material flow using system dynamics; development and evaluation of mercury stabilization technology with sulfur for long-term storage and disposal; risk evaluation of mercury exposure in a specific landfill site for mercury sulfide using computer simulations; and field surveys to estimate mercury use, emission and excess mercury in Asia region.

To consider approaches to recovery from products/wastes with intentionally added mercury, domestic mercury flow on fluorescent lamps was updated. Also, we conducted a questionnaire survey of hospitals, clinics and dentists to recover thermometer, blood pressure gauges, amalgam and so on. There are about 25 tonnes of mercury in use or in dead storage. A material flow model as easy-to-use toolkit to estimate the emission of mercury to the environment including air, water, soil and so on has been verified using Japanese data on mercury. We checked the applicability of vapor synthesis method and tumbling ball milling method as mercury stabilization technology with sulfur. These methods were compared to a previously developed method “planetary ball milling method” from viewpoints of environmental safety, reaction time, energy consumption and so on. The environmental risks of the landfill disposal of mercury sulfide have been evaluated. The possibility that environmental risks cannot be ignored for several cases was suggested. Parameters impacting environmental risk were identified. Reducing rainwater penetration in landfills was suggested as a practical, effective measure. As one of field surveys in Asia region, mercury emission inventory in Malaysia was established by collecting measurement data at municipal solid waste incinerators and a coal fired plant and literature data. Also, we evaluated the amount of excess mercury generated in Asia region from 2010 to 2050 using statistical data and reasonable scenarios.

Regarding lead and cadmium, we also constructed an emission inventory, evaluated the use of pollutant release and transfer registry (PRTR) data, and extracted and arranged a flow, which needs to be amended to develop a better material flow for lead and cadmium. In both lead and cadmium, the contribution of sectors on non-ferrous metal industry and waste treatment to the emission to the environment and the material flow was large, which suggests it is important to investigate these sectors in detail.

キーワード＝Mercury, Recovery, Appropriate management, Lead, Cadmium