Twenty years ago, when the Iron Curtain came down, the world gagged in horror as it witnessed firsthand the ravages inflicted on nature by the Soviet industrial machine.
Throughout the crumbling communist empire, sewage and chemicals clogged rivers; industrial smog choked cities; radiation seeped through the soil; open pit mines scarred green valleys. It was hard to measure how bad it was and still is: The focus was more on production quotas than environmental data.
Today, Europe has two easts _ one that has been largely cleaned up with the help of a massive infusion of Western funds and the prospect of membership in the prosperous European Union; another that still looks as though the commissars never left.
The contrasting story lines are written in the ripple and flow of two rivers.
Drifting along Ukraine's Dnieper River, past this one-time powerhouse of Soviet rule, requires slicing through clouds of black and orange exhaust from a metallurgical plant.
Over a hill, passengers may catch a whiff of a burning garbage dump. Nearby fields are fenced off by barbed wire with signs warning of radioactivity. Farther along, the cruise passes the world's third largest nuclear power station.
Upstream from Kiev, the Ukrainian capital, the Dnieper picks up water from the Pripyat River, whose sediment is still laced with radioactive caesium-137 from the 1986 Chernobyl nuclear disaster.
To the southwest, in countries that have joined the EU, another river, the Danube, is bouncing back. Pleasure boats sail past public bathing areas and people of dozens of nationalities stroll down esplanades alongside a glittering waterway that inspired the music of Johann Strauss. Protected woods and wetlands are being extended along its meandering course.
In 1989 the stretch of Danube that flowed through the communist countries was like the Dnieper _ an ecological disaster of epic proportions. Oil slicks glistened in rainbow colors on the water's surface. Long stretches were empty of fish, and stinking algae proliferated along the banks. Worse than the visible pollution was the insidious invasion of microcontaminants that poisoned the ecosystem.
But at the intersection of geography and history lie insights into the rivers' contrasting fates.
Originating in Russia and ending in the Black Sea, the Dnieper flows south through Belarus, cutting southeast across Ukraine, countries that have remained, in varying degrees, almost umbilically tethered over the past 20 years to the might of the Kremlin.
The Danube, on the other hand, traces a triumphant march through the European Union's eastward expansion, starting in traditional EU heavyweight Germany and flowing through or forming the border of new member states _ Hungary, Slovakia, Croatia, Romania, and Bulgaria.
The river ambles 2,857 kilometers (1,775 miles) from the Black Forest to the Black Sea. Some 83 million people in 19 countries live in its basin.
Five years after the Berlin Wall fell on Nov. 9, 1989, most of the countries sharing the Danube signed a convention to manage the river, its tributaries, the basin and the ground sources. It was one of the iconic projects in a broader mission among Western powers to make billions of dollars available for a massive cleanup of eastern Europe.
In five years of peak action from 2000, the Danube countries spent $3.5 billion building wastewater treatment plants in hundreds of towns and villages along the river and its 26 major tributaries. They spent $500 million more restoring wetlands and cleaning industrial spillage and agricultural runoff befouling the water.
Chemicals that feed plant-choking algae and threaten human health have dramatically declined since 1989, although their levels remain far higher than in 1950, before the industrial buildup and growth of riverside cities.
Along with direct Western aid, many poor ex-Soviet-bloc countries had a huge incentive to throw themselves into the region's cleanup: EU membership. Racing to meet the bloc's environmental standards, they put scrubbers into coal-fired plants, built water purification stations and capped emissions that had been returning to Earth as acid rain.
It was a monumental task.
One area known as the Black Triangle at the junction of Germany, Poland and the Czech Republic was notorious. A concentration of coal mines and heavy industry suffocated the region under industrial ash and gas. Some 80 million tons of lignite, or brown coal, were burned annually, pouring 3 million tons of sulfur dioxide into the air that caused chronic breathing ailments, higher cancer rates, and heart and immunity problems. Satellite images showed half the pine forests in the surrounding hills disappeared between 1972 and 1989.
With help from the EU, the three countries mothballed factories, switched to cleaner fuels, and installed new technologies in the area, about the size of Maryland or Belgium. Within a decade, sulfur dioxide emissions fell 91 percent, nitrogen oxide fell 78 percent and solid particles dropped 96 percent, according to the UN Environment Program.
For the Danube, the cleanup was more than just an environmental project. The Danube Convention changed mindsets, breaking down barriers between former enemies, forcing countries and riverside populations to work together across previously hostile borders.
"The Danube is a living river that is bound up with the culture and the peoples who live there," says Philip Weller, the commission's executive secretary.
"It is not a wild river, in the sense of salmon jumping or white water," Weller said. "It is the lifeblood, the circulation system" that connects the richest part of Europe in western Germany to the poorest in Ukraine and Moldova.
The river is still not pristine, but "over the past 20 years much has changed for the better," said Andreas Beckmann of the World Wildlife Fund. After 150 years of abuse and the loss of 80 percent of the river's wetlands, "the Danube has significantly recovered."
With the fund's support, dikes were torn down and severed river systems were reconnected, restoring 50,000 hectares (123,000 acres) or one-fifth of the retrievable wetlands, Beckmann says.
Still, the river bears irreparable scars from the Soviet era.
Romania's Iron Gate dams and hydroelectric stations cannot be dismantled, forever blocking the migration route of the majestic sturgeon. Two of the five sturgeon species native to the Danube have virtually disappeared, though efforts are on to revive stocks in the lower Danube.
Economic progress brings modern threats: more packaging, more waste, more household detergents containing phosphorous that stimulate river-choking algae.
Sergei Rudenko, a teacher at a vocational school in Dniprodzerzhynsk, has been throwing a fishing line into the Dnieper for 50 years. Springing from the mountains of central Russia, the 2,285-km (1,420-mile) river was once rich at this spot in eastern Ukraine with perch, carp and bream.
Now its yield is miserly, he says.
"The Dnieper is destroyed," Rudenko said, casting his line from a highway bridge, from which the horizon is obscured by smoke from the metallurgical plant. "The fishing is not like in earlier times. My father always brought home many fish, many bream, and now there is none."
Dniprodzerzhynsk, a name that combines the river with that of Felix Dzerzhinsky, the founder of the Bolshevik secret police, once was so crucial to the Soviet economy that it was closed to outsiders. With 250,000 people, it has 60 factories, some looming over the city in a permanent haze.
On the outskirts of town eight fields are fenced off with barbed wire, hung with yellow triangles warning of radioactivity. Nuclear waste was dumped here many years ago. Uniformed officers patrol the area, and stopped two Associated Press journalists to ask why they were there.
Next to a chemical plant is the city dump, where three decades worth of garbage is now a steaming landfill 30 meters (100 feet) deep. Dozens of trucks arrive daily, dropping more refuse into the ravine, cut through by a stinking scum-filled stream.
"When the wind is from there, I can't breathe," said Gregori Timoshenko, a 72-year-old waste site employee, nodding toward the fresh garbage. He shrugs when asked if working in such a polluted place affects his health. "I have lived my life, I have nothing to lose."
Not far away, Evgen Kolishevsky of the Voice of Nature, a local environmental group, takes a reporter to the foot a mountainous slag heap, below which runs the Konoplyanka river that feeds into the Dnieper. "This is the waste from chemical enterprises and of processing and enrichment of uranium," he said.
"Dniprodzerzhynsk is one of the most contaminated cities in Europe," he said, shaking his head.
As world attention increasingly focuses on climate change, a visit to Ukraine is a jolting reminder that the old environmental problems of air pollution, dirty water and untreated waste still exact a devastating toll.
The Ukrainian steppe, once the industrial engine for the Soviet empire, reveals a skyline of artificial landmarks: a picket fence of smokestacks and huge slag heaps looking like flat-topped volcanic hills in the distance.
At the end of its journey, the Dnieper enters the only part of the Black Sea that suffers from "anthropogenic hypoxia," a chronic lack of oxygen caused by man-made pollution afflicting 50,000 square kilometers (20,000 square miles) of water _ strangling fish and plant life.
Irina Schevchenko, a journalist and director of the local voluntary organization Vita, stands at the foot of one mountain of chemical ash, taller than any building in the eastern town of Gorlovka. In the 1970s, the state-owned chemical plant began dumping its waste at the edge of a nature reserve. Now, burned out tree stumps and a layer of steel-gray mud separate the dump from the woods.
In summer, smoke from chemical evaporation rises from the mound, said Schevchenko. "The wind takes it to the fields, to the houses of the people. When it rains ... it goes into these streams and gets into the underground currents. As a result, the concentration of chemicals in the soil and in the air of Gorlovka is twice as high as normal."
Victor Lyapin, a local health official, acknowledges the damaging effects.
"The first mistake of the Soviet Union," he said, "was to put factories and people shoulder to shoulder."