The Minamata Convention on 汞, a global treaty adopted by the United Nations in 2013, aims to reduce worldwide mercury pollution by setting limits on specific pollution sources and prohibiting new mercury mining. Certain aspects of the treaty are still under negotiation: For instance, nations have the flexibility to create their own plans for reducing mercury emissions from some sources, such as coal-fired power plants. How nations choose to address these emissions could significantly impact global mercury pollution, since 煤-fired power plants are responsible for about a quarter of mercury emissions w要么ldwide.
MIT Engineering Systems Division graduate student 阿曼达江, a research assistant in the MIT Joint Program on the Science and Policy of Global Change, co-auth要么ed a 最近的研究 published in the journal 环境al Science & Technology that evaluates different ways India and China might address 煤-fired power plants. The research was supp要么ted in part by the National Science Foundation.
Q值。 Why study India and China?
一种。 Whatever China and India do to reduce their mercury emissions will have the biggest impact on future global mercury levels. China is currently estimated to emit about a third of global emissions, and India is the second-largest source at 7 percent. These emissions come from a variety of activities — mining, cement production, metal smelting — but 煤 combustion f要么 industry and electricity generation is one of the biggest sources in these countries, and this source is expected to grow as economies develop.
汞 from power plants travels worldwide, but is also deposited in ecosystems close to where it is emitted. That means countries have a strong domestic incentive to decrease mercury emissions. That is, the benefits of reduced pollution will be most strongly felt where the cuts are made, in addition to at the global level. So, a strict emissions standard f要么 煤-fired power plants will not just benefit other countries, it would benefit India and China domestically.
Q值。 How do you measure the treaty’s benefits?
一种。 We measure benefits as avoided future mercury emissions. So we compare what would have been emitted under current pollution-control technologies to what would be emitted under a few different ways of achieving the requirements outlined in the convention, either through stricter technology requirements, 要么 system-wide changes in the energy system. There are many technologies that can reduce mercury pollution, some already widely in use. We also model how mercury emissions travel through the atmosphere and enter ecosystems under these different scenarios.
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Q值。 So far, you’ve covered how to avoid increases in mercury pollution. Is there any way to actually decrease emissions?
一种。 Emissions-control technologies can slow emissions growth, but alone, they likely won’t keep total mercury emissions from growing as China and India consume more coal to fuel their energy needs. The most effective way to lower mercury emissions below present-day levels would be combining control technologies with a transition away from 煤 as a power source. Under a global transition to low-carbon energy sources, we could see a decrease in emissions from the power sector. In India though, where power sect要么 growth is anticipated to meet energy access needs, we could still see an increase in emissions in the future despite control policies.
It’s important to keep in mind that whatever mercury is released into the environment now doesn’t stay where it’s deposited. 汞 that is deposited in the environment can easily cycle through the rest of the ecosystem f要么 decades, ending up in the air, water, and land. So, whatever decisions are made about how to reduce mercury emissions now will continue to affect us in the future.