(Bulletin of FFPRI) Vol.1 (No.42) 147-161 September 211 論 文 (Original article) 去 川 森 林 理 水 試 験 地 における 流 出 水 の 水 質 1)* 2) 3) 2) 1) 4) 4) 5) Streamwater chemistry at the Sarukawa Experimental Watershed Shuichiro YOSHINAGA 1), Yoshiyuki INAGAKI 2), Tsuyoshi YAMADA 3), Satoru MIURA 2), Akira SHIMIZU 1), Takanori SHIMIZU 4), Yasuhiro OGAWA 4), and Yasuo MIYABUCHI 5) Abstract Streamwater chemistry at the Sarukawa Experimental Watershed was observed to investigate its variation as a function of runoff rate and to evaluate annual nutrient runoff characteristics. The Sarukawa Experimental Watershed, located in Miyazaki Prefecture, southwestern Japan, consists of three forested watersheds that experience high annual precipitation of more than 25 mm. Most precipitation fell during the summer and autumn, resulting in seasonal variations in the runoff rate, which was high during the summer and autumn and low during the winter. Most solute concentrations in the streamwater also showed seasonal variation, with a strong negative correlation with the runoff rate. The streamwater chemistry is thus influenced by variations in hydrological characteristics. Annual nutrient runoff rates of Na +, Mg 2+, Ca 2+ and sulfur in the watersheds exceeded the annual atmospheric inputs observed at the Tano Station near the study watersheds, suggesting that most of these components are released from the soil and bedrock within the watershed by chemical weathering. On the other hand, annual nitrogen runoff rate at and watersheds from 1997 to 1999, and at No.1 watershed in 1997 and 1998, were lower than the annual atmospheric N input owing to retention by the plants within the watershed. However, at No.1 watershed in 1999, where annual precipitation reached 4375 mm, the annual N runoff rate exceeded the annual atmospheric nitrogen input, although streamwater nitrate concentrations in 1999 were similar to those in 1997 and 1998. This phenomenon is likely to be caused by rapid nitrate leaching from surface soils during a storm event, indicating that hydrological processes strongly affect nutrient budgets, particularly the nitrogen budget, within the watershed. Key words : Sarukawa Experimental Watershed, streamwater chemistry, nutrient runoff rate, nitrogen budge 3 1997 4 2 3 1997 1998 3 1999 NO 3 - NO 3-23 3 23 Received 23 March 211 23 5 23 Accepted 23 May 211 1) Kyushu Research Center, Forestry and Forest Products Research Institute (FFPRI) 2) Department of Forest Site, Forestry and Forest Products Research Institute (FFPRI) 3) Tohoku Research Center, Forestry and Forest Products Research Institute (FFPRI) 4) Department of Soil and Water Conservation, Forestry and Forest Products Research Institute (FFPRI) 5) Faculty of Education, Kumamoto University * 86-862 4 11 16 Kyushu Research Center, Forestry and Forest Products Research Institute (FFPRI), Kurokami 4-11-16, Kumamoto 86-862, Japan; e-mail: yoshinag@ffpri.affrc.go.jp
148 YOSHINAGA, S. et al. 1982; Muraoka and Hirata, 1988; 2; 22 2mm 25mm 1957 1997 4 2 3 ( 31 51 131 13 ) 1 ha 3 (Fig. 1 28 ) 25 km 3 ( : 6.56 ha : 26 37 m) ( : 9.17 ha : 23 36 m) ( : 8.18 ha 2 29 m) ( 196) (B A ) (B C ) (B D ) ( 1965) 3 ( Fig. 1 : : : M: 1:25, 1 Fig. 1 Location of the Sarukawa Experimental Watershed : Watershed No. 1, : Watershed No. 2, : Watershed No. 3 and M: Meteorological station. Fig. 1 Part of Arimizu 1:25, topographic map published by the Geographical Survey Institute was used. : : : M: 1:25, 1 3, 211 Fig. 1 Location of the Sarukawa Experimental Watershed : Watershed No. 1, : Watershed No. 2, : Watershed No. 3 and M: Meteorological station. Part of Arimizu 1:25, topographic map published by the Geographical Survey Institute was used.
Streamwater chemistry at the Sarukawa Experimental Watershed 149 1962) 192 196 1965 1966 1967 1997 3 1982 (43%) (28) 1996 1996 1992 6 2 m V 1987 2 14 (28) 14 571 mm (1993 ) 1913 mm (1994 ) 3294 mm 1997 4 2 3 1997 3 19 3 29 4 3 11 18 12 5 2 2 23 1997 11 18 12 16 2 2 23 1997 11 18 12 4 1998 1 25 2 5 11 17 2 2 23 25 ml 1997 4 2 3 1 3 2 36 4 (EC) (TOA CM-4V) ph (TOA HM-26S).45 μm Na + NH 4 + K + Cl - NO 3 - SO 4 (YOKOGAWA IC7D) Mg 2+ Ca 2+ Si ICP (PerkinElmer Optima3XL) (DIC).1 M - H 2 SO 4 ph 4.8 EANET (2) (L-Q ) L-Q 34 L-Q 1 1997 1998 1999 (DIN) Tukey-Kramer HSD (Pearson ) JMP5..1J (SAS Institute Japan ) 1997 1998 1999 3169 mm 2859 mm 4375 mm 1999 1987 2 14 1993 ( 28) 1997 1998 1997 1998 1999 1565 mm 1672 mm 3371 mm 158 mm 1511 mm 3157 mm 1611 mm 1753 mm 38 mm ( 28) 1999 3 3 mm 1997 1998 15 175 mm Bulletin of FFPRI, Vol.1,, 211
15 YOSHINAGA, S. et al. 1999 1 1 2 6 9 4 mm (Fig.2 3 4) 1998 7 8 1 mm 3.5 mm 1997 155 165 mm 1998 1999 1 13 mm (1985) 1967 1976 913 1121 mm 1998 1999 1997 1997 11 12 2 3 12 mm 1998 1999 ph EC Table 1 ph 3 7.3 EC 7.49 ms m -1 6.97 ms m -1 6.83 ms m -1 3 Mg 2+ Ca 2+ NO 3 - SO 4 Si Na + K + Cl - K + Cl - NO 3-3 DIC Fig. 2 ( ) Fig. 3 ( ) Fig. 4 ( ) 3 Na + Mg 2+ Ca 2+ SO 4 DIC Si Na + Mg 2+ Ca 2+ SO 4 DIC Si K + Cl - NO 3 - K +.1.2 mmol L -1 Cl -.1.12 mmol L -1.11.13 mmol L -1.9.11 mmol L -1 Cl - 3 99.5 mm 1998 6 2 1.5 mm 7 25 12 465 mm 1 mm 1999 8 5 Cl - Mg 2+ Ca 2+ SO 4 Si DIC NO 3-1997 11 26 1998 1 2 42 mm 38 mm 9 29 3 7 mm Table 2 3 4 Mg 2+ Ca 2+ SO 4 DIC r.8 (p<.1) Na + r NO 3 - K + (r=.296 p<.5) (r=.467.592 p<.1) NO 3 - Si Si Na + K + Cl - SO 4 Si NO 3 - (Fig.5) K + K + Cl - log (Q) Na + Mg 2+ Ca 2+ SO 4 DIC 3 (p<.1) (Fig.5 Table 2 3 4) L-Q Table 5 DIN Si 1 3, 211
Streamwater chemistry at the Sarukawa Experimental Watershed 151 Precipitation (mm day -1 ) 1 2 3 A Runoff rate (mm day -1 ) 1 1 1 B.1.15.1.5 C Cl - NO 3 - SO 4.25.2.15.1.5.6.5.4.3.2.1 D E Na + K + Mg 2+ Ca 2+ Si DIC JFMAMJJASONDJFMAMJJASONDJFMAMJJASONDJFM 1997 1998 1999 Fig. 2 (A) (B) (C) Cl - NO 3 - SO 4 (D) Na + K + Mg 2+ Ca 2+ (E) Si DIC Fig. 2 Variations of (A) daily precipitation, (B) daily runoff rate, (C) Cl -, NO 3 - and SO 4 concentrations, (D) Na +, K +, Mg 2+ and Ca 2+ concentrations and (E) Si and DIC concentrations at Watershed No. 1 Bulletin of FFPRI, Vol.1,, 211
152 YOSHINAGA, S. et al. Precipitation (mm day -1 ) 1 2 3 A Runoff rate (mm day -1 ) 1 1 1 B.1.15.1.5 C Cl - NO 3 - SO 4.25.2.15.1.5.6.5.4.3.2.1 D E Na + K + Mg 2+ Ca 2+ Si DIC JFMAMJJASONDJFMAMJJASONDJFMAMJJASONDJFM 1997 1998 1999 Fig. 3 (A) (B) (C) Cl - NO 3 - SO 4 (D) Na + K + Mg 2+ Ca 2+ (E) Si DIC Fig. 3 Variations of (A) daily precipitation, (B) daily runoff rate, (C) Cl -, NO 3 - and SO 4 concentrations, (D) Na +, K +, Mg 2+ and Ca 2+ concentrations and (E) Si and DIC concentrations at Watershed No. 2 1 3, 211
Streamwater chemistry at the Sarukawa Experimental Watershed 153 Precipitation (mm day -1 ) 1 2 3 A Runoff rate (mm day -1 ) 1 1 1 B.1.15.1.5 C Cl - NO 3 - SO 4.25.2.15.1.5.6.5.4.3.2.1 D E Na + K ; Mg 2+ Ca 2+ Si DIC JFMAMJJASONDJFMAMJJASONDJFMAMJJASONDJFM 1997 1998 1999 Fig. 4 (A) (B) (C) Cl - NO 3 - SO 4 (D) Na + K + Mg 2+ Ca 2+ (E) Si DIC Fig. 4 Variations of (A) daily precipitation, (B) daily runoff rate, (C) Cl -, NO 3 - and SO 4 concentrations, (D) Na +, K +, Mg 2+ and Ca 2+ concentrations and (E) Si and DIC concentrations at Watershed No. 3 Bulletin of FFPRI, Vol.1,, 211
154 YOSHINAGA, S. et al. Table 1 ( ) (n=36) (Tukey-Kramer HSD p<.1) Table 1 Solute concentrations for each watershed Arithmetic means (standard deviations) are shown. Different letters show the significant difference (p<.1) Watershed ph EC Na + K + Mg 2+ Ca 2+ Cl - NO 3 - (ms m -1 ) No.1 7.38 7.49 a.1674 b.139 b.116 a.1536 a.143 b.311 a.835 a.2495 b.4366 a (.15) (.91) (.115) (.24) (.185) (.257) (.81) (.91) (.178) (.287) (.595) 7.34 6.97 ab.1787 a.165 a.968 a.135 ab.1182 a.156 b.687 b.2888 a.4165 a (.15) (.77) (.117) (.29) (.146) (.221) (.82) (.67) (.12) (.35) (.557) 7.33 6.83 b.1725 ab.117 c.136 a.135 b.959 c.93 c.737 ab.2981 a.4249 a (.2) (1.27) (.159) (.23) (.257) (.346) (.76) (.54) (.195) (.367) (.922) SO 4 Si DIC Table 2 (log(q)) (* p<.5 ** p<.1 ) Table 2 Correlation matrix for streamwater chemistry and runoff rate (log(q)) at Watershed No. 1. Significant level: *p<.5, **p<.1 No.1 Na + K + Mg 2+ Ca 2+ Cl - - NO 3 SO 4 Si DIC K +.541 * Mg 2+.627 **.313 Ca 2+.615 **.349.995 ** Cl -.77 **.162.142.129 - NO 3 -.46.296 * -.116 -.82 -.114 SO 4.516 **.89.954 **.933 **.128 -.177 Si.371 *.526 * -.267 -.246.478 **.35 -.471 ** DIC.777 **.49 *.921 **.92 **.266 -.112.818 ** -.43 log(q) -.744 ** -.21 -.831 ** -.89 ** -.42 *.147 -.811 **.111 -.779 ** Table 3 (log(q)) (* p<.5 ** p<.1 ) Table 3 Correlation matrix for streamwater chemistry and runoff rate (log(q)) at Watershed No. 2. Significant level: *p<.5, **p<.1 Na + K + Mg 2+ Ca 2+ Cl - - NO 3 SO 4 Si DIC K +.396 Mg 2+.65 **.367 Ca 2+.526 **.365.991 ** Cl -.63 ** -.11 -.129 -.213 - NO 3.12.467 **.389.374 -.322 SO 4.23 -.13.84 **.86 ** -.43 **.275 Si.531 **.466 * -.73 -.17.612 ** -.257 * -.479 ** DIC.734 **.539 *.946 **.922 **.44.395.662 **.137 log(q) -.728 ** -.139 -.844 ** -.82 ** -.2 -.315 -.66 **.12 -.831 ** Table 4 (log(q)) (* p<.5 ** p<.1 ) Table 4 Correlation matrix for streamwater chemistry and runoff rate (log(q)) at Watershed No. 3. Significant level: *p<.5, **p<.1 Na + K + Mg 2+ Ca 2+ Cl - - NO 3 SO 4 Si DIC K +.376 Mg 2+.795 **.3 Ca 2+.756 **.294.994 ** Cl -.846 **.26 *.489 **.433 * - NO 3 -.5.592 **.72.33 -.92 SO 4.657 **.56.934 **.938 **.387 -.131 Si.46 *.354 * -.62 -.78.68 * -.154 -.219 DIC.856 **.368.981 **.966 **.57 **.84.871 **.61 log(q) -.827 ** -.317 -.833 ** -.786 ** -.614 ** -.255 -.714 ** -.48 -.852 ** 1 3, 211
Streamwater chemistry at the Sarukawa Experimental Watershed 155.4.3.2.1.4.3.2.1.4.3.2.1.4.3.2.1 Si No.1 Na + No.1 Ca 2+ No.1 Mg 2+ No.1.1.1 1 1 1 Runoff rate (mm day -1 ).6.5.4.3.2.1.4.3.2.1.4.3.2.1.1.5 NO 3 - No.1 Cl - No.1 SO 4 No.1 K + No.1.1.1 1 1 1 Runoff rate (mm day -1 ) Fig. 5 Fig. 5 Relationship between solute concentrations and daily runoff rate Fig. 5 Relationship between solute concentrations and daily runoff rate Bulletin of FFPRI, Vol.1,, 211
156 YOSHINAGA, S. et al. Table 5 *1: (21) *2: (22) *3: (1994) *4: (1991) *5: Baba and Okazaki (1998) *6: Ikeda and Miyanaga (21) *7: Kunimatsu et al. (21) *8: (2) *9: (1992) Table 5 Nutrient runoff rates for each watershed. Atmospheric input near the Sarukawa experiment watershed and results of nutrient runoff rates in other region in Japan were also shown. *1: Takagi and Nogami (21), *2: Committee of Acid Rain Monitoring Survey, Ministry of Environment (22), *3: Inokura et al. (1994), *4: Hirata and Muraoka (1991), *5: Baba and Okazaki (1998), *6: Ikeda and Miyanaga (21), *7: Kunimatsu et al. (21), *8: Asano et al. (2) and *9: Kunimatsu et al. (1992) Site Year Precipitation Runoff rate Na + K + Mg 2+ Ca 2+ Cl - DIN S Si DIC mm mm kmol ha -1 y -1 Nutrient runoff at the Sarukawa No.1 1997 3169 1565 2.38.2 1.3 1.81 1.53.49.92 4.2 5.52 1998 2859 1672 2.59.22 1.45 2.3 1.65.51 1.4 4.28 6.12 1999 4375 3371 5.3.43 2.63 3.68 3.25 1.6 1.85 8.7 11.38 mean 3468 222 3.34.28 1.79 2.51 2.15.69 1.27 5.67 7.67 1997 3169 158 3.47.33 1.59 2.19 2.44.23 1.16 6.16 7.16 1998 2859 1511 3.53.33 1.66 2.29 2.45.24 1.2 6.16 7.41 1999 4375 3157 7.11.68 3.12 4.28 5.7.46 2.29 12.91 14.18 mean 3468 259 4.7.45 2.13 2.92 3.32.31 1.55 8.41 9.58 1997 3169 1611 3..9 1.35 1.69 1.75.12 1.1 5.9 5.94 1998 2859 1753 3.34.11 1.56 1.95 1.94.14 1.16 6.44 6.81 1999 4375 38 5.43.13 2.31 2.88 3.21.21 1.74 1.99 1.27 mean 3468 2124 3.92.11 1.74 2.17 2.3.15 1.3 7.78 7.68 Atmospheric input near the Sarukawa Tano *1 1997-1999 3417 1.6.1.2.4 2..7.5 Ebino *2 2 2923.95.5.11.25.93.63.6 Shiiba-A *3 1991 4537.61.4.7.18.71.23.43 Shiiba-B *3 1991 514.52.13.9.23.61.46.81 Nutrient runoff in other regions Tsukuba (Ibaraki) *4 1985-1988 721 1.99.17.52.65 1.22.92.27 2.58 Hakyuchi (Tokyo) *5 1995 41.7.2.57.56.75.95.26 1.6 Jingahata (Yamanashi) *6 199 1979 1.32.27.18.9.41.17.3 2.92 2.93 Chugu (Ishikawa) *6 1988 2518 4.41.62 2.8 9.47 3.22.94 1.63 3.13 21.1 Aburahi-N (Shiga) *7 1989-1991 162 2.64.25.74 2.19 1.36.32. 2.67 Aburahi-S (Shiga) *7 1995-1998 772 1.94.9.52 1.9 1.31.21.17 1.87 Myokoji (Shiga) *7 1991-1992 1265 2.24.25.23.21.9.19.21 2.73 Kiryu (Shiga) *8 1995-1997 763 2.33.14.28.26.83 1.8 1..74.36 Jakujo (Shiga) *8 1995-1997 611 1.75.14.22.24.5.5 1.77.52.33 Rachidani (Shiga) *8 1995-1997 937 1.47.6.7.8.5.6.79 1.64.42 Asahinomori-R (Shiga) *9 1989 1636 2.8.13.46.29 2.46.9.29 1.75 Asahinomori-L (Shiga) *9 1989 114 1.75.5.37.27 1.59.6.19 1.8 Higashidani (Kochi) *6 1994 1821 1.2.15.56 4.62.82.28 1.16 1.15 7.56 DIN 3 1999 1997 1998 2 1999 1997 1998 2 ( 28; Fukushima and Tokuchi, 29) ( 26a; 26b) ( 1995; 1996) ( ; 1998; 24) 1 km 1 3, 211
Streamwater chemistry at the Sarukawa Experimental Watershed 157 Cl - Mg 2+ Ca 2+ SO 4 NO 3 -.3 mmol L -1 (1961) Cl - ( 22; 25 ) Cl - Cl - (Fig. 5) Na + Mg 2+ Ca 2+ SO 4 DIC (Fig. 2 3 4) Na + Mg 2+ Ca 2+ DIC ( 1988 ) SO 4 (S) ( 1981) SO 4 Na + Mg 2+ Ca 2+ DIC SO 4 Na + Mg 2+ Ca 2+ Si Si Mg 2+ Ca 2+ DIC Si Si Cl - Cl - Si Mg 2+ Ca 2+ Si Si Mg 2+ Ca 2+ Si Mg 2+ Ca 2+ NO 3 - NO 3 - (Muraoka and Hirata, 1988; 2 24; Shibata et al, 21; 26a 26b ) ( 24) NO 3 - NO 3 - NO 3 - Na + Mg 2+ Ca 2+ SO 4 DIC Si Bulletin of FFPRI, Vol.1,, 211
158 YOSHINAGA, S. et al. Cl - Si NO 3 - (Vitousek, 1977 ) (Likens et al., 197; Vitousek and Melillo, 1979 ) NO 3 - ( 25; 25; 28 ) 3 EC Mg 2+ Ca 2+ SO 4 Si NO 3-3 NO 3-1996 3 16 m 3 ha -1 14 m 3 ha -1 26 m 3 ha -1 1992 1996 3 ( 28) 3 3 Fig.5 Si NO 3-3 Si NO 3 - NO 3 - ( 196) 3 1997 1999 (Table 5 1998; 21 Table 5 4 km 4 2 21 ( 22) 7 km ( ) 1991 ( 1994) Na + Cl - DIN S K + B Na + Cl - 15 km 2 DIN.5 kmol ha -1 y -1 4.52 kmol ha -1 y -1 S 4.29 kmol ha -1 y -1 4 (Table 5) 3 1997 1999 Na + Mg 2+ Ca 2+ S K + 1 3, 211
Streamwater chemistry at the Sarukawa Experimental Watershed 159 Cl - DIN DIN Cl - DIN Cl - Cl - Cl - Cl - Cl - DIN.1.5 kmol ha -1 y -1 (Muraoka and Hirata, 1988) ( FM ; Baba and Okazaki, 1998) DIN (Table 5) 1997 1998 DIN.5 kmol ha -1 y -1 1999 1.6 kmol ha -1 y -1 1999 4375 mm 38 3371 mm 1997 1998 2 1999 NO 3-1997 1998 1999 DIN 1997 1998 2 NO 3 - NO 3 - NO 3-3.3 mmol L -1 DIN 1997 1998 DIN DIN NO 3-1997 1999 1999 1997 1998 Si 13 (Table 5) (Ikeda and Miyanaga, 21) Si DIC Si DIC Si DIC Si Ca 2+ 25 mm 3 Na + Mg 2+ Ca 2+ SO 4 DIC Bulletin of FFPRI, Vol.1,, 211
16 YOSHINAGA, S. et al. 3 Na + Mg 2+ Ca 2+ S 1999 NO 3 - DIN 1997 1998 DIN DIN NO 3 - (2) H + 82 27 Baba, M. and Okazaki, M. (1998) Acidification in nitrogen-saturated forested catchment, Soil Science and Plant Nutrition, 44, 513-525. EANET (2) Quality Assurance/Quality Control (QA/QC) Program for Wet Deposition Monitoring in East Asia, 29pp., http://www.eanet.cc/product/ qaqc/qaqcwet.pdf. (28) 9 6-16 Fukushima, K. and Tokuchi, N. (29) Factors controlling the acid-neutralizing capacity of Japanese cedar forest watershed in stands of various ages and topographic characteristics, Hydrological Processes, 23, 259-271. (1982) 64 8-14 (25) 22 31-39 (1988) 399 131-14 (1991) 35 15-11 Ikeda, H. and Miyanaga, Y. (21) Comparison of acid neutralization by chemical weathering between acidified and non-acidified watersheds, Water, Air, and Soil Pollution, 131, 47-436. (1994) ph 71 1-12 (22) 15 47485 (22) 4 114 pp http:// www.acap.asia/ acapjp/doc/4th_rain_measure_investigation.pdf (2) 13 227-239 (24) NO 3-86 27-36 (1961) 48 63-16 (1992) ( ) 2 13 81-94 Kunimatsu, T., Hamabata, E., Sudo, M. and Hida, Y. (21) Comparison of nutrient budgets between three forested mountain watersheds on granite bedrock, Water Science and Technology, 44, 129-14. Likens, G. E., Bormann, F. H., Johnson, N. M., 1 3, 211
Streamwater chemistry at the Sarukawa Experimental Watershed 161 Fisher, D. W. and Pierce, R. S. (197) Effects (196) 123 45-7 (1995) 4 55-59 (1996) of forest cutting and herbicide treatment on nutrient budgets in the Hubbard Brook watershedecosystem, Ecological Monographs, 4, 23-47. 5 37-38 Muraoka, K. and Hirata, T. (1988) Streamwater chemistry during rainfall events in a forested basin, Journal of Hydrology, 235, 235-253. (1998) 1997 ph EC 51 115-116 Shibata, H., Kuraji, K., Toda, H. and Sasa, K. (21) Regional comparison of nitrogen export to Japanese forest streams, The Scientific World, 1, 5758. (25) 87 34-35 (28) 1987 1 2 12 7 13-61 (26a) 6 (26b) 29 723-729 (1962) 14 89-99 (1965) 176 89-99 (1985) 67 115-125 (21) 43 53-58 (24) NO 3 -N 19 55-86 279-282 (1981) 32(3) 167-181 (25) 87 471-478 Vitousek, P. M. (1977) The regulation of element concentrations in mountain streams in the n o r t h e a s t e r n U n i t e d S t a t e s, E c o l o g i c a l Monographs, 47, 65-87 Vitousek, P. M. and Melillo, J. M. (1979) Nitrate losses from disturbed forests: patterns and mechanisms, Forest Science, 25, 65-619 Bulletin of FFPRI, Vol.1,, 211