Increases of wet deposition at remote sites in Japan from 1991 to 2009

Abstract

Temporal trends in wet deposition of major ions were explored at nationwide remote sites in Japan from April 1991 to March 2009 by using the seasonal Kendall slope estimator and the nonparametric seasonal Kendall test. For the trend analysis, datasets from eight remote sites (Rishiri, Echizenmisaki, Oki, Ogasawara, Shionomisaki, Goto, Yakushima, and Amami) were selected from the Japanese Acid Deposition Survey (JADS) conducted by the Ministry of the Environment. Deposition of H + has been increasing at remote sites in Japan on a national scale. Significant (p≤0.05) increases in H + deposition were detected with changes of +3-+9 %year −1 at seven sites, while insignificant increases were observed at one site. Depositions of non-sea salt (nss)-SO 4 2− and NO 3 − significantly increased at four and six sites, respectively, with changes of +1-+3 %year −1 . Significant increases in precipitation at four sites would have contributed to the increase in depositions of H + , nss-SO 4 2− , and NO 3 − . The emission trends of SO 2 and NO x did not corresponded to the deposition trends of nss-SO 4 2− and NO 3 − . The different trends indicated that temporal variation of precipitation amount trend dominated the deposition trends.

Sources and fluxes of organic nitrogen in precipitation over the southern East Sea/Sea of Japan

“…Oki Island (Japan), an island located down- Krishnamurthy et al (2010) wind of Uljin in the eastern section of the southern EJS ( Fig. 1), is mainly influenced by air masses originating from China and Korea, and shows a similar wet depositional flux of inorganic nitrogen to the values found in this study (45 mmol N m −2 yr −1 ; Japanese Acid Deposition Survey) (Kitayama et al, 2012). This implies that losses between the coast of Korea and offshore areas are small for wet depositional fluxes, as being shown for wet depositions of nitrogen over the eastern China Sea (Zhang et al, 2010).…”

Long‐term decrease in phosphate concentrations in the surface layer of the southern Japan Sea

“…Initially, the increase in the atmospheric nitrogen supply should enhance phytoplankton growth and phosphate consumption and, as the result, the phosphate concentration should decrease. Using the daily supply values for dry and wet nitrate depositions (51 and 114 μmol m −2 d, respectively [ Kitayama et al ., ; Nakamura et al ., ]) and the mean mixed‐layer depth of winter from this study (111 m depth), an increase in the nitrate concentration in the Tsushima Warm Current water of 1.5 nM d −1 was proposed for atmospheric deposition in winter. We calculated the residence time of the Tsushima Warm Current to be approximately 1 year because the ejection period (192 days) in the Tsushima Strait during May–October matched the period from May 1 to October 31 (184 days), and thus the Tsushima Strait water was almost entirely replaced during May–October.…”

“…Therefore, the phosphate decline is unlikely to be controlled by atmospheric deposition. Kim and Kim [] also rejected the effect of atmospheric nitrogen deposition in the JS, and the wet nitrogen deposition only increased by 2% per year (on average) from 1991 in the south‐western JS [ Kitayama et al ., ]. Therefore, the impact of atmospheric deposition on the JS's long‐term nutrient trends is very limited in the Tsushima Warm Current.…”

Study on Acidity and Neutralizing Ability of Ions in the Chemical Composition of Rainwater

“…SKM đã được phát triển bởi (Hirsch và cộng sự, 1982) nhằm mục đích phát hiện xu thế cho nồng độ các chất và các biến trong khí hậu [13]. SMK được áp dụng cho chuỗi dữ liệu theo tháng, theo mùa, đặc biệt SMK không nhạy cảm đối với các trường hợp bị thiếu dữ liệu và dữ liệu lỗi [14]. Sử dụng độ dốc Sen và SMK được áp dụng trong nhiều bài toán về đánh giá lắng đọng ướt [13][14][15][16][17][18][19].…”