The Increasing Problem of Nutrient Runoff on the Coast

摘要

The world's coastal ecosystems are under stress. The numbers tell the story: Over 50 percent of the global population resides within 100 kilometers of a coastline, a thin ribbon of land that includes three-fourths of the mega-cities with more than 10 million residents. Farms and factories needed to sustain all those people release fertilizers and toxic chemicals into our rivers, streams, and estuaries. Degraded water quality is the most obvious result, but the onslaught of nutrients has a more insidious effect. Fertilizer runoff causes coastal algae to proliferate; the algae take most of the oxygen in the water, causing fish to die and disrupting the food chain for humans and other organisms. As coastal populations keep increasing, the stresses are increasing with them.