Why the English–Wabigoon river system is still polluted by mercury 57 years after its contamination

Between 1962 and 1969, 10 tonnes of mercury were discharged from a chlor-alkali plant in Dryden, Ontario, to the English–Wabigoon River. Present-day fish mercury concentrations are amongst the highest recorded in Canada. In 2017, the Grassy Narrows Science Team found no evidence of ongoing discharges from the plant site to the river water, even though large quantities of mercury remain at the site. Instead, our data suggest that ongoing erosion of high mercury particles by the river, as it meanders through contaminated floodplains, is responsible for present-day transport of mercury to Clay Lake and to Ball Lake, located 154 km downstream. In Clay Lake, surface sediment total mercury concentrations and inflow water concentrations are still about 15 times above background (86 km downstream), and in Ball Lake mercury concentrations in sediments appeared to be still increasing. The remobilization of legacy inorganic mercury from riverbank erosion between Dryden and Clay Lake stimulates methyl mercury production there, in Clay Lake, and in Ball Lake. The large quantities of methyl mercury produced between Dryden and Clay Lake are mostly dissolved in water and are swept downstream, elevating concentrations in water and biota throughout the system. Several options for remediating the ongoing contamination are discussed.

The International Mercury Cartel, 1928–1954: Controlling Global Supply

This article describes the features of the international mercury market during the first half of the twentieth century. It analyzes the various market agreements made, their effectiveness, and their consequences. The period studied is little understood, although it was one in which mercury production greatly increased. It was also one that saw persistent efforts at market manipulation, owing to a series of agreements between Spanish and Italian producers that proved very effective until the arrival of shipments of mercury produced by Soviet bloc members and by some developing countries.

The effect of mercury contaminants in major gas developments

Over the past ten years the region has witnessed the unforeseen presence of mercury during gas production which has affected projects not only in southeast Asia but more recently in Australian waters. This has caused major operational challenges and has often involved costly production impairment, loss of condensate sales value and major brownfield modifications. Today–s awareness of mercury has seen a new vigilance in well testing programmes intended to address the identification of mercury in gas streams during the early appraisal and concept development phases of an asset lifecycle. This paper looks at the ways in which operating companies have resolved the issue of unforeseen mercury production to date, and the operational experience and lessons learned. The paper describes some of the fundamental testing programmes as well as the available technologies for treatment and removal of mercury from production and effluent streams. It also identifies the impact of mercury on the design and operation of specific parts of the process as well as the overall impact on facility topsides. The impact of mercury on a development is shown to be manageable and least costly where identified and addressed during the conceptual stage of a project development. Technical, environmental, safety and regulatory issues associated with mercury can be tackled, minimising risk of production deferment, and the costs incurred can be quantified and incorporated into economic models.