DAMPAK TRANSFORMASI NITROGEN TERHADAP LINGKUNGAN BIOTIK DI DANAU TONDANO PROVINSI SULAWESI UTARA (The Impact of Nitrogen Transformation on The Biotic Environment in The Lake Tondano North Sulawesi) - Wantasen, Sofia (Pusat Studi Lingkungan Hidup Universitas Gadjah Mada, 2012)