Every rain shower washed radiation from the clouds and flushed more long-lived nuclear isotopes into the ponds and streams. The arrival of autumn would send radioactive leaves skittering across the ground. The Pripyat marshes—the largest swamp in Europe—had become a massive sponge for strontium and cesium, and the vast stretches of agricultural land proved too large to be scraped clean even by squadrons of earth-moving machines.
