Atmospheric mercury in the Latrobe Valley, Australia: Case study June 2013

Robyn Schofield,Samuel Adeloju,Caitlin Gionfriddo,Roger Dargaville,Michael Tate,David Krabbenhoft,Melita Keywood,Steven Utembe,Mike Sandiford

doi:10.1525/elementa.2021.00072

Abstract

Gaseous elemental mercury observations were conducted at Churchill, Victoria, in Australia from April to July, 2013, using a Tekran 2537 analyzer. A strong diurnal variation with daytime average values of 1.2–1.3 ng m–3 and nighttime average values of 1.6–1.8 ng m–3 was observed. These values are significantly higher than the Southern Hemisphere average of 0.85–1.05 ng m–3. Churchill is in the Latrobe Valley, approximately 150 km East of Melbourne, where approximately 80% of Victoria’s electricity is generated from low-rank brown coal from four major power stations: Loy Yang A, Loy Yang B, Hazelwood, and Yallourn. These aging generators do not have any sulfur, nitrogen oxide, or mercury air pollution controls. Mercury emitted in the 2015–2016 year in the Latrobe Valley is estimated to have had an externalized health cost of $AUD88 million. Air pollution mercury simulations were conducted using the Weather Research and Forecast model with Chemistry at 3 × 3 km resolution. Electrical power generation emissions were added using mercury emissions created from the National Energy Market’s 5-min energy distribution data. The strong diurnal cycle in the observed mercury was well simulated (R2 = .49 and P value = 0.00) when soil mercury emissions arising from several years of wet and dry deposition in a radius around the power generators was included in the model, as has been observed around aging lignite coal power generators elsewhere. These results indicate that long-term air and soil sampling in power generation regions, even after the closure of coal fired power stations, will have important implications to understanding the airborne mercury emissions sources.

Highlights

Australia is one of the original 128 signatories to the UNEP Minamata convention on mercury signed on January 13, 2013
The observed gaseous elemental mercury (GEM) values at Churchill displayed in Figures 5–7 show a strong diurnal variation
Overnight (6 PM–6 AM), the observed mercury averages ranged from 1.6 to 1.8 ng m–3, and during the day (6 a.m.–6 p.m.), an average of 1.2–1.3 ng m–3 was observed (Figure 5). These average observed values are significantly higher than the annual averages reported for Cape Grim of 0.85–0.96 ng m–3 and the Southern Hemisphere monitoring stations of 0.85– 1.05 ng m–3 for the 2007–2013 period (Slemr et al, 2015). This indicates that the atmospheric Total Gaseous Mercury (TGM) in the Latrobe valley is elevated, perhaps

Summary

Introduction

Australia is one of the original 128 signatories to the UNEP Minamata convention on mercury signed on January 13, 2013. Australia is among the remaining 34 original signatories yet to ratify the convention. Mercury readily vaporizes and in its elemental form undergoes global transport residing in the atmosphere for up to 1 year (Selin et al, 2007). Human activities have increased the atmospheric concentration of mercury by 5.5–7.6 times the natural baseline, and the deposition enhancement ranges between 3 and 5-fold (Biester et al, 2007; Amos et al, 2013; Outridge et al, 2018, and references therein). Australian mercury emissions from natural and human activities of both diffuse and stationary nature are provided in Figure 1 for 2015/2016 from

Methods

Results

Conclusion