Seasonal and Annual Fluxes of Inorganic Constituents in a Small Catchment of a Japanese Cedar Forest near the Sea of Japan

Autor: Akiomi Takahashi, Tsumugu Totsuka, Masato Kamisako, Taeko Matsui, Makoto Nakata, Takuji Oida, Hiromasa Ueda, Hiroko Suzuki, Hiroyuki Sase
Rok vydání: 2008
Předmět:
Zdroj: Water, Air, and Soil Pollution. 195:51-61
ISSN: 1573-2932
0049-6979
Popis: Fluxes of major ions in rainfall (RF), throughfall plus stemflow (TF + SF), and stream water (SW) were measured for five water years in a small catchment of a Japanese cedar forest near the Sea of Japan. The fluxes of most ions in RF and in TF + SF, including the non-sea-salt constituents, increased from late autumn to midwinter owing to the seasonal westerly wind. The concentrations of most ions in SW showed no obvious seasonal trend during the study period, whereas $${\text{NO}}_3 ^ - $$ concentrations were lowest in summer, with a small seasonality. The Ca2+ and Mg2+ outputs in SW were approximately 3.7 and 1.8 times the TF + SF inputs of these cations, respectively. The large net outputs of base cations in the catchment may indicate a decrease in the soil's acid-neutralizing capacity. Annual dissolved inorganic nitrogen inputs in RF and in TF + SF were 17.7 and 17.9 kg N ha−1 year−1, respectively, which exceeded previously published thresholds in Europe and the U.S. (i.e., the values at which these inputs increased $${\text{NO}}_3 ^ - $$ levels in SW) and equaled the highest level of nitrogen deposition previously reported in Japan. The $${\text{NO}}_{\text{3}} ^{\text{ - }} $$ concentrations in SW were relatively high even in summer. During high-precipitation events, $${\text{NO}}_{\text{3}} ^{\text{ - }} $$ concentrations in SW increased with increasing water discharge, and the pH decreased simultaneously during several events. Nitrogen deposition may contribute to the high $${\text{NO}}_{\text{3}} ^{\text{ - }} $$ concentrations in SW and the temporary acidification that occurred during the rain events.
Databáze: OpenAIRE
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