Two half-hour documentaries will debut Wednesday evening on Planet Green: Focus Earth with Bob Woodruff: Troubled Waters (10 p.m. ET/PT) and Acid Test: The Global Challenge of Ocean Acidification (10:30 p.m. ET/PT), produced by the Natural Resources Defense Council and narrated by actress Sigourney Weaver.

As the documentaries reveal, our oceans, freshwater rivers, lakes and streams have become increasingly plagued by dead zones, toxic runoff and dying wildlife. Fish populations are in serious decline, and carbon dioxide pollution is making the oceans more acidic.

Woodruff shows how banks and shores in every part of the world are facing similar threats. Among his interviewees is Robert F. Kennedy Jr., chief prosecuting attorney for the environmental group Riverkeeper.

Acid Test explains that since the Industrial Revolution, the ocean has absorbed 25% of all carbon dioxide emissions produced by burning fossil fuels, causing a 30% increase in ocean acidity. Sea creatures’ shells dissolve, threatening the ocean’s ecosystem.

For Your Organic Bookshelf: Smithsonian Ocean: Our Water, Our World

Photo: Scott Gries/Getty Images