March 2008, Vol. 20, No.3


Composting Toilets Serve Bronx Zoo Visitors

At a new exhibit at New York’s Bronx Zoo, visitors are requested to make a small contribution. Donations will support water conservation, help flowers grow, and provide healthy meals for red worms, fungi, and bacteria.

According to a news release from the Bronx Zoo, the zoo has installed new ecorestrooms available in part of the zoo, featuring composting toilets. The toilets, according to the U.S. Environmental Protection Agency, use 95% less water per flush, eliminate wastewater flowing to New York’s treatment plants, and create fertilizer via a composting process. The toilets also feature an innovative flush mechanism. Instead of the nearly 7.57 L (2 gal) of water used with each flush of a conventional toilet, these facilities accomplish the task with only 90 mL (3 oz) of water and a cascade of biocompatible foam, according to the press release.

Sinks in the ecorestroom are equipped with low-flow faucets, in which excess water is used to irrigate the graywater garden outside the building, where plants will naturally filter it. The restrooms help protect the Bronx River and educate more than 500,000 visitors annually about the value of water efficiency and recycling.

Cartoon animals that praise the “power of poop” adorn the stalls and walls of the skylit lavatory. But the graphics, from the children’s book The Truth About Poop by Susan Goodman and illustrated by Elwood Smith, are more than silly scatological humor. They’re also practical, according to the zoo’s news release, offering advice on conserving resources at home and even providing a recipe for a homemade drain cleaner that won’t harm wildlife.

The zoo said the restrooms were created as a conservation measure, as well as a reminder of humans’ intimate connection with Earth.  

Study Links Sea Levels, Drinking Water Threat

As sea levels rise, coastal communities could lose up to 50% more of their freshwater supplies than previously thought, according to a new study from Ohio State University (OSU; Columbus). The U.S. Geological Survey states that about half of the United States gets its drinking water from groundwater.

University hydrologists have simulated how saltwater will intrude into freshwater aquifers, given the sea level rise predicted by the Intergovernmental Panel on Climate Change (IPCC). IPCC has concluded that within the next 100 years, sea level could rise as much as 584 mm (23 in.), flooding coasts worldwide, according to an OSU news release.

Scientists previously assumed that as saltwater moved inland, it would penetrate underground only as far as it did above ground.

But this new research shows that when saltwater and fresh water meet, they mix in complex ways, depending on the texture of the sand along the coastline, OSU notes. In some cases, a zone of mixed, or brackish, water can extend 50% farther inland underground than it does above ground.

Motomu Ibaraki, associate professor of earth sciences at OSU, led the study. Graduate student Jun Mizuno presented the results in October at the Geological Society of America (Boulder, Colo.) meeting in Denver.

“Almost 40% of the world population lives in coastal areas, less than 60 km from the shoreline,” Mizuno said. “These regions may face loss of freshwater resources more than we originally thought.”

“Most people are probably aware of the damage that rising sea levels can do above ground, but not underground, which is where the fresh water is,” Ibaraki said. “Climate change is already diminishing freshwater resources, with changes in precipitation patterns and the melting of glaciers. With this work, we are pointing out another way that climate change can potentially reduce available drinking water. The coastlines that are vulnerable include some of the most densely populated regions of the world.”

Scientists have used the IPCC reports to draw maps of how the world’s coastlines will change as waters rise, and they have produced some of the most striking images of the potential consequences of climate change.

Ibaraki said that he would like to create similar maps that show how the water supply could be affected, according to OSU. That’s not an easy task, since scientists don’t know exactly where all of the world’s fresh water is located or how much is there. Nor do they know the details of the subterranean structure in many places, OSU states.

Contact Ibaraki at