A global treaty called the Minamata Convention requires gold-mining countries to regularly report the amount of toxic mercury miners use to find and extract gold, and is designed to help countries measure success toward at least cutting back on practices that produce the largest man-made amount in the world. Mercury contamination.
But a study of estimates of baseline mercury emissions reported by 25 countries — many developing countries in Africa, South America and Asia — found that those estimates rarely provide enough information to know whether changes in the rate from year to year are the result. Actual change or uncertainty in the data.
Key variables – such as how a country determines how much gold to produce – can lead to vastly different baseline estimates. However, countries often do not report this range of possible estimates.
Millions are at risk
Around 15 million artisanal and small-scale gold miners around the world risk their lives every day facing hazardous working conditions that include constant exposure to mercury – a powerful neurotoxin. Mercury vapors cause debilitating effects on the nervous system, digestive system, immune system, lungs, and kidneys, and may be fatal. Mercury is particularly harmful to children and pregnant women, whose developing fetuses are particularly vulnerable to neurotoxic effects.
An estimated 4 to 5 million of the 15 million artisanal miners are women or children.
“To make mercury interventions and policies effective and impactful, you must first make sure that the baseline emissions estimate is correct,” said Kathleen M. Smits, chair of the Department of Civil and Environmental Engineering and Solomon Professor of Global Development in SMU’s Lyle School of Engineering. “Providing more transparency in their reporting will help with that.”
Smits joined civil engineers from the University of Texas at Arlington and the US Air Force Academy in the study, which was recently published in the journal Environmental Science and Policy. The work was supported by the National Science Foundation.
The research group analyzed 22 countries’ National Action Plans (NAP), which included their annual baseline estimates compiled under the Minamata Convention and published on the organization’s website. The team also considered three additional countries with relevant information posted on national government or non-governmental websites.
Smits and co-authors calculated baseline estimates for Paraguay, if different variables were used. The South American country was chosen for analysis in this study, due to the transparency of its reporting.
Lack of basic data in baseline estimates for countries
Baseline mercury emissions estimates seek to quantify the number of kilograms of mercury pollution that are pumped into the atmosphere each year from the practice of artisanal gold mining. To do this, countries count the amount of gold miners have found – thus an approximation of how much mercury was used to obtain it.
Countries collect this information primarily using interviews with miners, gold and mercury traders, and other major players in the gold mining business; ratios that calculate the ratio of mercury to gold; Previous research and field visits to known mining sites.
But the study points out major problems with the way these estimates are currently calculated:
- There is not enough data on gold production estimates. Fifteen countries, such as the Central African Republic and Madagascar, provide only one source for calculating the rate of gold production, but as Zimbabwe demonstrates, different data sources can provide vastly different values. In a separate study, Zimbabwe reported that information on extraction, processing, and miners’ income led to gold production estimates ranging from 11 percent to 55 percent using 2012 mining data and 9 percent to 35 percent using 2018 mining data. The African country’s goal is to reduce emissions Mercury is a smaller percentage of the uncertainty range the study found for gold production.
- Countries have not been standardized on how they select important metrics. The ratio of mercury to gold (Hg: Au) is used to estimate the amount of mercury used to produce a given amount of gold. The different ratio can lead to different reasonable estimates of the amount of mercury emitted. In the study, five different methods were listed as percentage for mercury: the au, and a few countries mentioned more than one method in their NAP. Similarly, different countries have used different techniques to come up with a national estimate of mercury emitted, some based on a small sample of mines and others without checking the data with other sources.
Smits said countries need to do a better job of accounting for these variables if they are to formulate more meaningful mercury reduction targets in their national action plans.
“If you just look at the baseline mercury emission estimation process, it is clear that the NAP program will not achieve its goal of reducing mercury emissions if they continue to current approach. Miners in gold mining countries to study.
Why do miners use toxic mercury to get gold?
Artisanal and small-scale miners—the term given to individual miners, families, or small groups with minimal or no mechanization to do the work—sift rock into rivers and dump mercury grains over sediments that cling to gold. Then they light a match, using the flame to separate the mercury from the gold, a process that releases toxic fumes into the air.
It’s a cheap way to mine gold, but mercury can leach toxins into the air and contaminate water systems.
Hazardous gold mining accounts for nearly 40 percent of all man-made mercury emissions, making it the largest source of this type of pollution, says the United Nations.
In 2013, the United Nations created a global treaty called the Minamata Convention to try to phase out ASGM, as well as other contributors to mercury emissions. This treaty currently has 139 countries committed to its objective.
To join its treaty, countries that regularly engage in artisanal gold mining are required to report estimates of baseline mercury emissions on a regular basis and submit a national action plan for how to ultimately reduce their country’s mercury footprint. Munifa Thomas Nguyen