Transboundary nitrogen pollution from continental China to a river that flows into the Sea of Japan

Miyazako, T.; Tabayashi, Yu; Ohshiro, Hitoshi; Koyama, Y.; Nakashima, Y.; Sato, Sachiko; Nojiri, Yukari; Kishi, Masashi; Fujihara, Atsuo; Kamiya, Hiroshi

doi:10.3739/rikusui.75.27

Cited by 7 publications

(1 citation statement)

References 15 publications

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“…Within the watershed in 2000, 81.3% of the basin was forest, 6.1% was occupied by rice and other field crops, and 12.6% consisted of residential areas and other types of human use, such as abandoned fields of rice and other crops. By 2010, those land use areas had changed to 81.0%, 3.1%, and 15.9%, respectively (Miyazako et al ). The population of the catchment area was 63,000 in 2000, and it had decreased to 56,500 in 2010.…”

Section: Methodsmentioning

confidence: 99%

Long-term trends in nitrogen and phosphorus concentrations in the Hii River as influenced by atmospheric deposition from East Asia

et al. 2015

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Deposition of atmospheric nutrients is known to alter oligotrophic ecosystems such as the open ocean, but the role of such nutrients in the further deterioration of eutrophic aquatic ecosystems is largely unknown. The Hii River watershed in Japan encompasses lagoons that have been eutrophic since 1980s. This study examined the atmospheric deposition of nitrogen and phosphorus in the Hii River watershed and the nitrogen and phosphorus concentrations in the Hii River over an 11-yr period. Total nitrogen (TN) concentrations of both precipitation and river water were significantly higher in cold months (November-March) than in warm months (April-October). Most of the TN was nitrate, which suggests that the TN source was atmospheric nitrogen from East Asia transported by seasonal winds. In contrast, total phosphorus (TP) concentrations of both precipitation and river water were significantly higher in warm months. Over time, the TN concentration in the river water showed a decreasing trend although the trend was not significant, while the TP concentration increased significantly. This was attributed to an increase in the atmospheric deposition of TP originating from East Asia since 2000. The increase in the deposition of atmospheric phosphorus might also have increased phosphorus leakage from the soils. In this work, the TN : TP ratios for both atmospheric deposition and river water indicate that changes in atmospheric nutrient deposition affect loading rates and N : P ratios. These changes, especially the latter, could have significant ecological effects in eutrophic systems by lowering the N : P ratios, which could induce cyanobacteria blooms.

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Section: Methodsmentioning

confidence: 99%