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Nitrogenous Compounds on Carbon Steel in Eutrophic Freshwaters Te effects of nitrogenous compounds in eutrophic freshwaters on the corrosion of carbon steels (CS) were evaluated by electrochemical methods and surface analysis experiments. Te results showed that as the concentration of total nitrogen increased, corrosion rate of CS decreased. Different corrosion mechanisms of typical nitrogenous compounds are also discussed. 54 MATERIALS PERFORMANCE November 2012 Effect ofW ith the rapid economic devel- opment and increasing popu- lation expansion, water pollu- tion has become an urgent problem. Eutrophication is a phenome- non in which processing operations dis- charge nutrients (nitrogen, phosphorus, etc.) to lakes, reservoirs, and other waters, causing excessive pollution.1 In a water distribution system, there are many metal pipelines and facilities. The water quality, changed by eutrophication,2 the corrosion of metal.3 may affect There has been much research on the corrosion of metal in seawater, but studies on corrosion of metal in eutrophic freshwaters are few.4-5 Excess nitrogenous compounds and phosphorus compounds are the main reasons for eutrophication.6 According to preliminary test results, the freshwater in East Lake (Wuhan City, Hubei Province, China) contains heavy eutrophic fresh- water with an annual average concentra- tion of total N2 (TN) of ~0.71 mg/L. This LI JIANG, YULING SONG, LISHAN TU, LIXIA SUN, YUNDAN YU, HONGLIANG GE, AND GUOYING WEI, China Jiliang University, Hangzhou, China is 10 times higher than that in clean freshwater (Danjiangkou Reservoir, the source of the South-to-North Water Di- version Project in Danjiangkou City, Hubei Province).2 The aim of the present investigation is to highlight the effect of TN concentrations and typical nitroge- nous compounds (ammonium sulfate [(NH4 )2 SO4 ], thiourea [H2NCSNH2 nitrate [KNO3 ], potassium nitrite [KNO2 ], and potassium ]) on the corrosion of car- bon steel (CS) in eutrophic freshwaters. This research can offer not only guide- lines for corrosion prevention of pipelines and facilities, but also provide reference for suitable materials selection. Materials and Methods The eutrophic freshwater was taken from East Lake. According to the results of the previous water quality analysis,7 cleaner East Lake water was taken as a control, then eight types of ammonium salts, azide nitrogen, nitrate, nitrite, and NACE International, Vol. 51, No. 11