Terrawatch: Roman records show lasting effects of pollution

Sediment cores drilled from Swiss lake reveal it took 300 years to bounce back after Romans departedAll over the world lakes are in trouble. An excess of nutrients - from fertilisers, detergents and sewage - is upsetting the balance of life, leading to algal blooms and bottom-water dead-zones. Many places are now trying to clean up their act, but how long does it take for a lake to recover? Sediment cores drilled from a Swiss lake reveal how long it took for the lake to bounce back after the Romans departed, and indicate we might have to wait centuries for today's polluted lakes to become properly fresh again. Continue reading...