地理漫步·世界地理英语30篇（4）

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波罗的海：面临富营养化的半封闭海域

The Baltic Sea receives freshwater from 250 rivers but exchanges saltwater slowly with the North Sea.
Its low salinity supports unique brackish-water species found nowhere else on Earth.
Agricultural runoff rich in nitrogen and phosphorus triggers massive algal blooms each summer.
Dead zones—oxygen-depleted areas—now cover over 60,000 square kilometers annually.
Fishermen report declining cod stocks linked to warmer, less-oxygenated deep waters.
The Helsinki Commission coordinates pollution reduction across nine riparian countries.
Wetland restoration along coastlines filters nutrients before they reach open water.
New EU regulations limit fertilizer use and mandate buffer strips near waterways.
Citizen science projects map bloom locations using smartphone apps and satellite alerts.
Eco-labeling for sustainable seafood helps consumers support responsible fishing practices.