Readers discuss accessible images in print and potassium’s climate potential

Accessible images

A recent study calls into question the long-standing assumption that male mammals tend to be larger than females, Jonathan Lambert reported in “Mammal size rule needs rethinking” (SN: 4/6/24, p. 12).

Reader Bernard Larner pointed out that the chart in the story showing rates of sexual size dimorphism in different mammalian orders was not accessible to people who have red-green color blindness.

A gray-scale version of that chart, which is interpretable to those who have red-green color blindness, is shown in the sidebar below.

Science News is committed to making our stories accessible to all readers. We typically run charts through a color-blind checker before publication, but we missed this one.

We appreciate our readers for keeping us accountable.

Potassium’s climate potential

Several methods aim to strip excess carbon dioxide from the atmosphere and stash it in the ocean to help slow climate change. But more research is needed on how these methods could impact ecosystems, Carolyn Gramling reported in “Ocean to the rescue” (SN: 4/6/24, p. 22).

One potential way to enhance the ocean’s uptake of carbon dioxide is to increase the water’s acid-buffering ability by adding finely ground alkaline minerals, Gramling reported.

Reader Brian Graham wondered whether potassium hydroxide, sourced from used alkaline batteries, could do the trick. Repurposing used batteries in this way would also reduce the waste that ends up in landfills, he noted.

Graham’s out-of-the-box idea is interesting, but it’s unclear whether it would be economically attractive, Gramling says.

Used alkaline batteries contain various ingredients, including potassium hydroxide, zinc oxide, steel and plastic. None of these materials are particularly valuable, Gramling says. They can also be expensive to process, creating barriers to recycling to recover the raw materials.

“There isn’t really a market out there right now for specifically recovering the potassium hydroxide from the waste,” Gramling says.

What’s more, researchers would still need to study the environmental impact of dumping excess potassium into the ocean, Gramling says.