global south

Tracking atmospheric mercury

May 13, 2025 By EarthWise Leave a Comment

Atmospheric mercury is a toxic pollutant released into the air from natural sources—such as volcanoes and wildfires—and from human activities like coal burning and gold mining. Once in the atmosphere, mercury can travel long distances before settling onto land or into water, transforming into toxic forms that threaten ecosystems and human health.

But tracking atmospheric mercury is a costly and challenging endeavor, requiring specialized equipment and trained personnel. Active monitors, which pump air to collect mercury, are expensive and need electricity, while passive samplers, using activated charcoal for remote areas, cost up to $100 each.

Researchers from Cornell University have found a cheap method for tracking toxic atmospheric mercury near gold mining sites throughout the Global South: wild fig trees. In the study, which was conducted in the Peruvian Amazon and recently published in the journal Frontiers in Environmental Science, the research team found that the rings in wild fig trees can serve as natural archives of atmospheric mercury, capturing and preserving historical pollution levels over time.

The technique itself is not actually new. Previous studies have used tree rings to track mercury pollution from coal combustion, particularly in Canada. But the research team wanted to test this method in regions of the Global South, where mercury emissions from gold mining are widespread.

According to the research team, wild fig trees might soon serve as an important biomonitoring tool, helping scientists better understand how mercury disperses across landscapes and through time.

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Tree rings track atmospheric mercury cheaply

Photo, posted November 13, 2012, courtesy of Steve Kessler via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Coastal Land Reclamation | Earth Wise

April 3, 2023 By EarthWise Leave a Comment

People are artificially expanding the coastlines of cities by extending industrial ports and creating luxury residential waterfronts. Major cities have added 900 square miles to their coastlines just since 2000.

A recent study published in the journal Earth’s Future made use of satellite imagery to analyze land changes in 135 cities with populations of at least 1 million. But population growth is not the only driver of coastal land reclamation. It is popular in places that are eager to enhance their reputation and promote revenue growth.

At present, coastal land reclamation is most common in the Global South, where many economies are growing. In the past, the Global North dominated the use of coastal land construction.

The largest additions to land area occurred in China, Indonesia, and the United Arab Emirates. Port extension is the most common reason for development. Shanghai alone has added 135 square miles of land.

New land is typically created by piling sediments in the ocean, building cement sea walls and structures to contain sediments or cement, or sometimes filling in wetlands and other shallow areas of water near the coast. The ecological impacts of reclamation are immense and, unfortunately, are not always considered. Projects affect both the local ecosystems as well as those of the places where fill materials are obtained.

Industrialization and the need for urban space have driven much coastal reclamation. Some projects, such as the palm-tree-shaped artificial islands of Dubai, are essentially for prestige. Some cities, including Shanghai, are building new land in consideration of future sea level rise.

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New Land Creation on Waterfronts Increasing, Study Finds

Photo, posted October 15, 2010, courtesy of Werner Bayer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Onshore Algae Farms | Earth Wise

November 9, 2022 By EarthWise Leave a Comment

According to some estimates, food production will need to increase by 50% by 2050 in order to feed a projected global population of 10 billion people. How can this be achieved?

One solution, according to researchers at Cornell University, could be to grow nutritious and protein-dense microalgae in seawater-fed onshore aquaculture systems.

According to the research, which was recently published in the journal Oceanography, growing algae onshore could close a projected gap in society’s future nutritional demands while also improving environmental sustainability.

Climate change, environmental degradation, limited arable land, and lack of freshwater will all constrain the amount of food that can be grown in the coming decades. Wild fish stocks are already heavily exploited, and there are limits to how much finfish, shellfish, and seaweed aquaculture can be produced in the coastal ocean.

As a result, the researchers argue for expanding algae production in onshore aquaculture facilities. The research team’s models found that the best locations for onshore algae farming facilities are along the coasts of the Global South, including desert environments.

Algae can grow as much as ten times faster than traditional crops. Algae can also be produced in a manner that is more efficient than agriculture in its use of nutrients. In addition to its high protein content, algae also provides nutrients lacking in vegetarian diets, such as essential amino acids, minerals, and omega-3 fatty acids.

Algae could become the breadbasket of the Global South.

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Onshore algae farms could feed the world sustainably

Photo, posted June 17, 2011, courtesy of NOAA Great Lakes Environmental Research Laboratory via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio