Changing carbon of the Mekong River Siyue Li 1,2*, Richard T. Bush 1 1. Southern Cross GeoScience, Southern Cross University, New South Wales, 248, Australia 2. Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 4714, China Supplementary materials Figs. S1-S9 Tables. S1-S5 References. 1
Fig. S1. Lower Mekong River showing main-channel stations (Chiang Saen represents the Upper Mekong catchment, while Pakse, the most downstream station with available water discharge, thus represents the whole basin) (This map is created using Photoshop CC 214). 2
25 3 2 TSS =.1825Q - 21.988, R² =.59 25 F TSS = 3.33E-5Q 2.182, R² =.83 15 1 2 15 1 5 5 4 35 3 2 Ca = 71.646Q -.128, R² =.28 3 25 2 15 F Ca =.233Q + 6.5283, R² =.96 1 Mg = 33.345Q -.219, R² =.26 1 5 F Mg =.44Q + 3.8944, R² =.82 25 8 Concentration (mg/l) 2 15 1 5 16 14 12 1 8 6 4 2 25 Na = 151.85Q -.366, R² =.59 K = 2.3866Q -.4, R² =.29 HCO 3 = 323.52Q -.148, R² =.6 SO 4 = 183.67Q -.37, R² =.23 Flux (kg/s) 6 4 2 12 1 8 6 4 2 8 F Na =.48Q + 8.7666, R² =.83 F K =.17Q +.735, R² =.93 F HCO =.858Q + 33.398, R² =.98 3 F SO =.121Q + 11.928, R² =.7 4 2 Cl = 237.4Q -.452, R² =.42 6 F Cl =.36Q + 8.27, R² =.48 15 1 5 (a) Si= 11.926Q -.11, R² =.18 2 4 6 8 1 12 14 Q (m 3 /s) 4 2 F Si =.43Q + 1.5868, R² =.95 2 4 6 8 1 12 14 (b) Q (m 3 /s) Fig. S2. Scatter plot s between instantaneous water discharge and concentrations (a) and fluxes (b) in the station Chiang Saen of Mekong River. 3
18 16 14 12 1 8 6 4 2 4 TSS =.1Q 1.5482, R² =.67 35 3 25 2 15 1 5 7 F TSS = 1E-7Q 2.5482, R² =.84 3 Ca = 77.915Q -.143, R² =.41 6 5 F Ca =.18Q + 21.553, R² =.96 2 4 3 1 Mg = -.783ln(Q) + 11.233R² =.14 2 1 F Mg =.32Q + 5.34, R² =.71 25 25 Concentration (mg/l) 2 15 1 5 Na = 94.839Q -.39, R² =.36 K = -.79ln(Q) + 2.364, R² =.1 Flux (kg/s) 2 15 1 5 F Na =.39Q + 14.545, R² =.76 F K =.15Q +.8458, R² =.75 12 1 HCO 3 = 264.64Q -.137, R² =.4 25 2 F HCO 3 =.664Q + 67.871, R² =.96 8 6 4 2 SO 4 = 152.4Q -.267, R² =.33 15 1 5 F SO4 =.152Q.7329, R² =.78 18 3 15 12 Cl = 365.27Q -.464, R² =.4 25 2 F Cl =.37Q + 17.718, R² =.47 9 15 6 1 3 5 Si= 13.624Q -.16, R² =.1 F Si =.5Q + 2.376, R² =.88 (a) 5 1 15 2 25 3 35 Q (m 3 /s) (b) 5 1 15 2 25 3 35 Q (m 3 /s) Fig. S3. Scatter plot s between instantaneous water discharge and concentrations (a) and fluxes (b) in the station Pakse of Mekong River. 4
Modelled TSS (kg/s) 3 2 1 y =.866x + 142.94 R² =.79, p<.1 Modelled Ca (kg/s) 3 2 1 y =.966x + 2.6357 R² =.96, p<.1 Modelled Mg (kg/s) 6 4 2 y =.834x + 2.6545 R² =.82, p<.1 Modelled Na (kg/s) Modelled Cl (kg/s) 8 6 4 2 1 2 3 Observed TSS (kg/s) y =.8331x + 3.5124 R² =.83, p<.1 2 4 6 8 8 6 4 2 Observed Na (kg/s) y =.4795x + 8.9861 R² =.48, p<.1 2 4 6 8 Observed Cl (kg/s) Modelled K (kg/s) Modelled SO 4 (kg/s) 25 2 15 1 5 25 2 15 1 5 1 2 3 Observed Ca (kg/s) y =.9189x +.352 R² =.93, p<.1 5 1 15 2 25 Observed K (kg/s) y =.712x + 12.695 R² =.7, p<.1 Modelled HCO 3 (kg/s) 5 1 15 2 25 Observed SO 4 (kg/s) Modelled Si (kg/s) 12 1 8 6 4 2 6 4 2 2 4 6 Observed Mg (kg/s) y =.9831x + 4.251 R² =.98, p<.1 2 4 6 8 112 Observed HCO 3 (kg/s) y =.9367x +.679 R² =.95, p<.1 2 4 6 Observed Si (kg/s) Fig. S4. Validation of modelling approach (comparison of instantaneous observed fluxes and modelled values, data are from station Chiang Saen). 5
.4 Mean: 27.6% (2.1%-37.7%).3 Discharge rate.2.1. 1.2 1. Mean: 42.5% (17.1%-18.8%).8 TSS rate.6.4.2..5 Mean: 36.4% (28%-47.4%).4 TDS rate.3.2.1. 196 1965 197 1975 198 1985 199 1995 2 25 26 Year Fig. S5. The contributions of water discharge, TSS and TDS from upper catchment to the Mekong River (reflected by the ratio of the fluxes from Chiang Saen to Pakse). 6
45 4 y = 2.381x + 138.19, R 2 =.2888 55 5 y = 7.815x.683, R 2 =.293 Q Pakse 35 3 TDS Pakse 45 4 35 25 3 (a) TSS Pakse (b) 2 4 6 8 1 12 14 Q Chiang Saen 4 35 3 25 2 15 1 5 2 4 6 8 1 12 14 16 18 2 22 TSS Chiang Saen 25 1 12 14 16 18 2 22 TDS Chiang Saen y = 17.979x.52, R 2 =.2484 5 y = 8.3758x.385, R 2 =.9122 4 Pakse TDS (c) 6 3 2 Chiang Saen 1 y = 4.5221x.283, R 2 =.9187 5 1 15 2 25 3 35 4 (d) TSS Fig. S6. The relationships between water discharge (a), TSS (b) and TDS (c) loads, as well as between TDS and TSS (d) at the both stations (Chiang Saen and Pakse) (unit in km 3 /y for water discharge, Mt/y for TSS and TDS loads). 7
Fig. S7. Ternary plot showing relative abundance of cations (a and b) and anions (c and d) (unit in mg/l). 8
1 Silicate 1 Na/Ca.1.1 Dolomite Calcite.1.1.1 1 (a) Chiang Saen 1 Mg/Ca Silicate 1 Na/Ca.1.1 Dolomite Calcite.1.1.1 1 (b) Pakse Mg/Ca Fig. S8. Scatter plots between Na/Ca and Mg/Ca (molar ratio) in the stations (a-chiang Saen, b-pakse) of the LMR (End-members of rocks are from Gailardet et al., 1999 and Li et al., 214). 9
14 12 y =.572x + 5.7534 R² =.42, p<.1 Flow (km3/y) 1 8 6 (a) (c) 4 1 12 14 16 18 Precipitation (mm/year) 25 2 15 P/R 1 5 (b) (d) 196 197 198 199 2 21 Year Fig. S9. Temperature (a) and rainfall (b) in five stations (Lincang, Simao, Lancang, Jinghong and Mengla) of upper Mekong River over 196-21. Mean temperature variations as year: T =.284Year - 36.447, R²=.72, p<.1. (c) Relationships between river discharge at Chiang Saen and annual mean precipitation in the upper basin, (d) Changes in the ratio of precipitation (P) to runoff (R) (P/R; unit in mm for precipitation, while km 3 /year for runoff) in the upper basin (red line means smoothing analysis that averages the values at neighboring points). 1
Table S1. Main channel stations of the LMR included in this study Stations Country Location Distance from the River mouth Drainage area Pre-regulated period Regulated period Total latitude longitude km 1 3 km 2 1923-1991 1992-27 Chiang Thailand 2.16.4 1.5. 2363 189 Saen a Water discharge (km 3 /y) 85.8 83.9 85.2 TSS (Mt/y) 64.7 61.1 63.5 TDS (Mt/y) 14.3 14.1 14.2 Pakse b Lao PDR 17.7 15.48. 869 545 Water discharge (km 3 /y) 32.9 314.1 319.7 TSS (Mt/y) 171.4 167.4 17.7 TDS (Mt/y) 4.5 39.7 4.4 a data are from the time period of 196-27, b data are from the time period of 1923-26. 11
Table S2. Comparison of annual mean concentrations in the LMR (unit in mg/l). TSS Ca Mg Na K HCO 3 Cl SO 4 Si TDS Chiang Saen Observed mean Mean 317.53 27.76 7.14 9.96 1.86 18.8 9.41 2.58 5.56 188.51 Max. 727.83 31.22 9.34 11.34 2.36 126.18 12.33 31.1 6.9 221.59 Min. 63.24 23.98 4.7 8.24 1.48 93.62 7.42 8.99 4.7 167.45 S.D. 174.94 1.87 1.16.8.26 7.26 1.32 5.32.51 11.85 Observed Q-weight mean Mean 687.91 25.81 5.98 8.33 1.75 99.93 6.9 17.1 5 17.7 Max. 132.66 28.76 6.82 9.25 1.96 18.66 8.86 21.51 5.52 186.78 Min. 293.8 23.29 4.68 7.69 1.6 93.45 5.65 13.52 4.32 161.16 S.D. 35.3 1.77.63.53.13 4.84 1.3 2.52.33 8.39 Q-weight mean (predicted) Mean 718.83 25.3 5.65 7.93 1.73 97.16 6.26 15.36 4.87 164.25 Max. 1573 26.9 6.25 9.31 1.74 14.26 7.58 17.62 5.14 178.8 Min. 329.51 23.55 5.1 6.54 1.72 89.49 4.97 13.4 4.58 148.9 S.D. 28.99.6.22.5 2.64.48.83.1 5.38 Pakse Observed Mean Mean 171.8 22.93 4.62 6.59 1.54 82.61 8.8 15.68 5.84 149.21 Max. 59.6 28.6 5.91 9.28 3.5 94.91 12.3 29.4 7.46 164.14 Min. 64.92 17.5 3.1 2.48.63 68.49 4.34 6.25 4.14 131.54 S.D. 17.25 2.15.8 1.89.5 6.15 2 4.26.85 8.41 Observed Q-weight mean Mean 478.45 2.56 3.78 5.13 1.45 74.44 5.47 12.84 5.28 129.24 Max. 87.1 23.88 5.91 6.7 2.8 84.5 8.99 17.7 7 142.48 Min. 175.15 19.8 1.98 2.14.51 63.9 3.56 5.49 3.49 119.39 S.D. 25.51 1.33 1.1 1.18.56 5.73 1.51 3.58 1.5 6.82 Q-weight mean (predicted) Mean 519.24 19.74 3.68 4.98 1.46 71.1 4.52 11.87 4.92 122.16 Max. 844.84 21.1 4.2 5.69 1.47 75.37 5.5 13.32 5.15 131.53 Min. 262.68 18.89 3.43 4.54 1.45 68.7 3.94 1.94 4.76 116.2 S.D. 123.27.46.13.25.1 1.58.34.51.9 3.36 Observed mean is measured variables, Observed Q-weight mean is measured variables with water discharge weight, while Q-weight mean (predicted) is concentration derived from models. 12
Table S3. Statistics of dissolved and particulate material fluxes in the LMR. Discharge Flux (Mt/y) Chiang Saen km 3 /y TSS 1 Ca 1 Ca 2 Mg 1 Mg 2 Na 1 Na 2 K 2 HCO 31 HCO 32 Cl 1 Cl 2 SO 41 SO 42 Si 1 Si 2 TDS 2 Mean 85.21 63.52 2.15 2.19.48.5.67.69.15 8.25 8.36.53.53 1.3 1.41.41.42 14.24 Max. 126.98 199.74 2.99 3.17.64.68.83.89.22 11.36 11.95.63.63 1.66 1.91.58.6 2.4 Min. 61.11 2.14 1.64 1.63.38.39.57.57.11 6.37 6.3.46.47 1.8 1.12.31.31 1.89 S.D. 12.4 29.25.26.29.5.5.5.6.2.97 1.6.4.4.12.15.5.5 1.73 Pakse Mean 319.69 17.69 6.29 6.43 1.17 1.19 1.58 1.71.47 22.63 23.37 1.43 1.74 3.77 3.77 1.57 1.67 4.35 Max. 43.85 341.19 7.68 7.95 1.41 1.46 1.86 2.3.59 27.65 28.96 1.63 2.5 4.49 4.48 1.93 2.9 49.55 Min. 215.55 57.84 4.53 4.56.87.86 1.23 1.3.32 16.25 16.45 1.19 1.36 2.87 2.87 1.11 1.15 28.86 S.D. 43.76 6.31.73.79.12.14.15.17.6 2.65 2.91.1.16.37.37.19.22 4.82 1 represents model1 2 represents model 2 13
Table S4. Comparison of global watershed physical characteristics, concentrations, fluxes and yields of DIC and major solutes. (a) Lithology (data are from Amiotte Suchet et al., 23) Area Discharge Runoff Sands and sandstone Shales Carbonate Shield Acid Volcanic Basalts 1 3 km 2 km 3 /y mm % % % % % % 1(a) Amazon (upper) 583 6223 167.4 16.7 51 3.9 27 1.9 1(b) Amazon (lower) 583 6223 167.4 16.7 51 3.9 27 1.9 2 Amur 187 47 217.6 11.9 28 54 6.5 3 Brahmaputra 583 612 4 Chao Phraya 16 3.4 19 5 Colorado 67 28 41.8 55.6 1 34 6 Columbia 62 269 433.9 1.4 13 44 33.4 8.4 7 Danube 74 14 189.2 3.3 67 14.5 16 8 Don 39 31 79.5 94 5.9 9 Fraser 24 14 433.3 69 22 9.5 1 Ganges 16 459 11(a) Ganges-Brahmaputra 1643 171 651.9 15.4 32 33.8 18 1.4 11(b) Ganges-Brahmaputra 1643 171 12 Godavari 3 147 49 3.9 62 34.5 13 Yenisei 244 665 272.5 6.4 12 6.9 38 36 14 Indigirka 34 54 158.8 39.9 6 15 Indus 88 251 285.2 16.8 24 26 33 16 Irrawaddy 4 459 1147.5 3.6 14 44 11 17 Kolyma 59 122 26.8 72.3 28 18 Lena 232 393 169.4 1.8 39 11.2 34 5.1 19 Limpopo 31 27 87.1 25 14.2 39 21.6 2 Mackenzie 147 26 176.9 54 2.6 26 21 Magdalena 26 313 123.8 23.8 29 4.8 24 19.1 22(a) Mekong (Chiang Saen) 189 85.2 45.8 14
22(b) Mekong (Pakse) 545 319.7 586.6 8.4 43 21.4 18 2.9 5.8 22(c) Mekong 82 623 759.8 8.4 43 21.4 18 2.9 5.8 23 Mississippi 313 57 182.1 25.3 48 18.1 8.7.3 24 Murray Darling 111 4 36.9 72 21 2.7 2.9 25 Niger 15 166 11.7 57.8 6.3 35.8 26 Nile 184 125 67.9 31.9 2.5 45 2.4 27 Ob 31 477 158.5 19.8 72 2.7 2.7 3 28 Orange 66 26 39.4 68.8 9.8 17 4.8 29 Orinoco 96 759 79.6 17.7 47 1.3 3 3.8 3 Parana 284 666 234.5 27.3 44 1.2 15.8 12.3 31 Red 12 123 125 32 Salween 325 211 649.2 33 Sao Francisco 59 119 21.7 14 8 39.8 38 34 Senegal 36 15 41.7 64.5 3.2 29 3.3 35 Severnaia Dvina 3 97 323.3 1.9 78 1.8 36 Xijiang 352 23 653.4 82.4 18 37 St. Lawrence 87 36 413.8 6.1 24.9 69 38 Tigris-Euphrates 93 156 167.7 17.2 26 42.5 2.2 11.3 1 39 Yana 21 25 119 5.6 49 4 Yangtze 174 98 521.8 13.9 7.9 44 34 41 Yellow 75 33 44 27.6 5.9 7.6 59 42 Yukon 78 169 216.7 85 15 43 Zaire 36 1298 36.6 46.6 1.1 42 1.4 44 Zambesi 131 19 83.2 45.9 13.6 39 1.8 World total 14817 374 252.4 26.3 25.3 13.4 27.6 2.3 5.1 15
(b) Land cover composition (data are mainly from Ludwig et al., 1996 and http://multimedia.wri.org/watersheds_23/) FTSS Elev. Slope SoilH APPT AT Veg C SoilC NPP PopD FDOC FPOC POC% DOC POC Land cover (%) t/km2/yr m radian cm mm C kg/m2 kg/m3 kg/m2 h/km2 t/km2/yr t/km2/yr % tss Forest Grass, Savanna And Shrub Vegetation Wetland Cropland Irrigated Cropland Urban 1(a) 1(b) 2 3 4 5 6 7 8 9 1 11(a) 11(b) 12 13 14 15 16 17 18 19 2 21 mg/l mg/l 19 455.434 226 284 24.4 11.7 13.3.669 4 4.461 2.826 6.9 4.46 2.83 73.4 1.2 83.6 8.3 14.1.1.6 28 571.699 137 479-1.6 6.9 12.7.472 33 53.8 8.8 62.6 4.4 18.4.8 2.6 182 18.5 44.7 63.2 2.7 29.4 3.7 2.4 119 35.4 11.1 46.5 8.4 44.7 12.5 9.2 19 155.1718 176 283 11.7 4.2 6.6.322 9 17 74.9 91.9 2.5.9 2 6.9 22 1336.2197 232 482 7 8.5 1.7.442 16.795.98 2.12.26 5 35.5 85.5 6.3 6.4 3.6 7.3 83 514.125 154 766 9.1 4.1 1.7.577 125 18.2 3.2 21.4 1.4 66.9 5.2 1.7 18 138.147 234 434 6.2 1.2 8.4.5 47.6.252 8.81 3.69 1.4 5.4 6.8.5 83.1 3.2 8.8 91 1173.2555 178 66 4.5 14.2 12.585 4 85.7 6.2 91.9 1.7.4 4.1 41 4.2 13.4 17.6 17.7 72.4 22.7 6.3 668 146.1353 153 1443 2.3 3.7 11.477 316 2.215 5.222 3.87 9.13 9.8 25.6 35.4 18.9 55.6 15.3 4.8 55 399.433 154 1132 26.3 3.8 8.6.568 26 6.8 22.5 29.3 1.2 64 11.7 6.7 5 769.855 93 356-4.5 7.6 12.6.377 3 39.7 32.4 72.1 2.7 12.8 1.3 39 738.1261 37 23-14.5 3.6 13.1.241 1 2.4 69.7 72.1 3.1 26 1671.1476 92 56 18.5 2.2 9.3.331 165 2.929 1.794.46 14.4 8.82.4 46.4 46.8 4.2 3 24.1 4.6 62 745.1477 242 1825 22.4 8.5 9.7.631 79 56.2 9.7 65.9 6.3 3.5 3.4 1.9 9 59.1195 24 267-1.9 3.7 12.8.246 1.7 45.3 46 1.3 5 68.857 49 337-8.6 6 12.9.318 1 64.7 11.4 76.1.6 1.7.4 8 795.498 189 645 21 3.2 6.8.434 32.7 67.7 68.4 2.8 26.3.9 4.5 23 634.964 184 339-4.2 8.2 12.4.375 1.838.855 2.95 4.93 5.3 66 14.7 8.7 48.9 2.6 1.9 92 1224.2527 194 1934 23.7 5.3 12.2.548 83 37.2 14.8 52.2 35.8 2.4 1.3 16
22(a) 22(b) 22(c) 23 24 25 26 27 28 29 3 31 32 33 34 35 36 37 38 39 4 41 42 43 44 2 854.858 21 1644 22.5 8.1 1.5.69 71 2.81 1.18 2.2 4.75 2 41.5 17.2 58.7 8.7 37.8 2.9 2.1 2 854.858 21 1644 22.5 8.1 1.5.69 71 2.81 1.18 2.2 4.75 2 41.5 17.2 58.7 8.7 37.8 2.9 2.1 12 646.497 214 776 1.3 3.1 11.1.487 27 1.319.32 8.79 2.14 22.2 28.5 5.7 2 35.8 3.1 12.7 29 272.337 161 469 18.5 4 7.8.444 6 8 62.1 7.1 3.4 28.4 1.6 1.2 33 337.33 294 168 27.4 3.1 8.8.467 43.593.414 3.27 3.71 2.59.9 68.6 69.5 4.1 4.4.1.5 4 892.577 221 944 24.3 2.8 8.454 46.89.116 2.95 3.85 2 53 55 6.1 1.7 1.4 1 6 35.345 216 393 -.6 4.4 2.46 1 1.182.115 9.9.88 33.9 16 49.9 11.2 36.9.5 3 1 1255.484 16 362 18.1 1.4 4.8.318 1.25.16 2.18 2.5 1.6.2 85 85.2.8 6.5 2.2 15 347.549 228 2359 26.1 8.2 11.2.592 17 5.5 37.8 88.3 15.3 7.6.2 2.6 3 53.443 228 1155 21.5 3.3 15.424 26 1.432.279 2.64 8.68 1.69 18.1 33 51.1 1.9 43.3.5 4.2 11 897.1315 36 1597 21 7.7 9.2.65 191 43.2 15.5 58.7 5.4 36.3 3.9 2.1 43.4 48.3 91.7 9.5 5.5.4.5 9 627.449 261 1141 23.1 4 6.1.468 45 3.1 31.8 34.9 9.7 6.2.3 2.8 8 223.216 133 76 28.4 2.7 5.7.466 1.72 1.5.1 68.2 68.3 3.6 4.8.1 13 127.141 342 474 8.1 14.4.466 6 4.498.197 13.63.6 83.4.4 83.8 1.5 11.7 3 149 598.85 198 151 19.8 2.8 6.8.463 194 9.6 6.1 15.7 1.3 66.5 5.2 5.3 4 274.47 21 837 4.4 5.8 1.9.519 59 1.632.326 5.98 3.75.75 43.5.1 43.6 47.2 16.4.2 14.5 57 625.933 2 282 18.6 1.6 5.5.332 57 1.2 47.7 48.9 2.9 25.4 9.1 6.2 14 746.129 3 129-14.8 3.5 13.5.235 25 1527.1321 196 174 14.4 5.3 1.4.457 226 5.69 6.144 2.52 12.37 13.36 6.3 28.2 34.5 3 47.6 7.1 3 14 1838.1197 179 485 9.2 2 8.5.367 156.481 14.678.7 6.25 19.63 1.5 6 61.5 1.1 29.5 7.2 5.9 71 748.1468 219 337-4.9 4.2 14.7.251 1.953.37.32 4.14 1.33 64 27.6 91.6 27.8.4 11 775.37 31 152 24 8.4 12.5.63 15 2.465.68 7 7.25 2 44 45.4 89.4 9 7.2.2 18 4 72 76 7.6 19.9.1.7 17
(c) Concentrations (data without reference are from Gaillardet et al., 1999) ph TDS TSS Na K Ca Mg Cl SO 4 HCO 3 SiO 2 T z + mg/l mg/l μmol/l μmol/l μmol/l μmol/l μmol/l μmol/l μmol/l μmol/l Source 1(a) 122 278 28.9 477 96.7 183 73 1122 185 1454.3 Stallard and Edmond, 1983 1(b) 38 182 63.4 2.8 129 39.8 3.5 17.8 323 12 421.8 Stallard and Edmond, 1983 2 55 72 126 26 223 95 66 65 477 36 788 3 7.6 11 16 1 5 39 17 2 6 111 16 127 Galy and France-Lanord, 1999 4 5 6 115 64 217 28 45 26 86 115 133 15 1557 7 428 313 739 51 1473 1117 159 66 3328 69 597 8 829 8 6348 26 273 1481 42 224 3295 5 13482 9 1 7.6 13 11 18 7 47 2 9 8 142 13 159 Galy and France-Lanord, 1999 11(a) 196 613 69 71 496 169 146 2684 158 394 Sarin et al., 1989 11(b) Galy and France-Lanord, 1999 12 193 1619 352 56 755 99 43 14 1721 352 2116 13 112 23 226 26 413 152 271 14 939 138 1382 14 34 137.5 66.667 7.423 96.875 165.574 48.334 SCOPE 42 - Biogeochemistry of Major World Rivers 15 8.21 158 191 68 637 21 73 313 16 71 1953 Karim and Veizer, 2 16 21 535 134 51 25 247 514 52 1967 167 2349 17 52 29 275 8.451 5 472.131 113 SCOPE 42 - Biogeochemistry of Major World Rivers 18 92 74 1 36 141.5 25 72 867 67 187 Huh et al., 1998a 19 238 1269 896 118 483 56 46 54 2361 295 2992 2 7.5 29 134 33 26 89 337 226 369 183 5 281 18
21 118 928 361 49 375 136 383 15 88 21 1432 22(a) 7.6 164.3 718.8 344.7 44.3 632.4 235.3 176.5 16. 1592.7 174. 2124.44 This study 22(b) 7.7 122.2 519.2 216.6 37.4 493.5 153.1 127.2 123.6 1164 175.6 1547.2 This study 22(c) 263 321 663 48 11 367 448 343 235 167 3447 23 216 862 478 72 85 366 294 266 192 127 2982 24 453 1271 4391 154 525 7 4886 396 1541 83 6995 25 59 26 78 28 138 78 26 5 549 233 538 26 388 14 2261 2 775 576 1257 542 2852 213 5163 27 126 4 23 26 465 21 186 89 1279 43 166 28 29 27 132 61 21 7 2.5 251 3 11 5 263 Nemeth et al., 1982 3 86 139 231 94 173 86 185 21 69 285 843 31 8.2 172 157 54 24 842 151 17 32 1968 169 264 Moon et al., 27 32 36 435 26 115 658 571 1 3475 477 33 34 35 36 7.76 185 259 47 791 271 69 125 233 115 243 Zhang et al., 27 37 168 12 239 35 75 247 214 146 1656 4 2268 38 8.33 277 279.6 36.9 1165.3 38.8 583.1 241.7 2521.3 211.7 348.7 Varol et al., 213 39 3 16 137.5 7.292 273.77 595 SCOPE 42 - Biogeochemistry of Major World Rivers 4 7.8 22 52 325 59 87.5 346 161 177 211 13 2691 Chen et al., 22 41 8 491 269 227 41 1115 19.5 1797 999 328 719 Chen et al., 25 42 183 286 113 31 795 295 31 233 1787 128 2324 43 33 32 87 33 11 7 76 41.5 116 161 48 Meybeck, 1984 44 8 194 235 49 265 169 186 31 525 28 1152 WSM 127 148 26 5 187.5 96 19.5 1256 134 1549 Meybeck, 24 WDWA 97 24 44 297 122.5 167 87.5 798 145 1123 Meybeck, 24 19
WSM-World spatial median; WDWA-World discharge-weighted average. (d) Fluxes TDS TSS Na K Ca Mg Cl SO 4 HCO 3 SiO 2 Source Mt/y Mt/y 1 9 mol/y 1(a) Stallard and Edmond, 1983 1(b) 236.5 117.7 394.5 129.4 82.8 247.7 189.8 11.8 21 746.8 Stallard and Edmond, 1983 2 22.4 52.4 51.3 1.6 9.8 38.7 26.9 26.5 194.1 14.7 3 56 648.7 55 29 211 94 19 91 473 78 Galy and France-Lanord, 1999 4 1.9 5 127.3 44.9 6 3.9 13.6 58.4 7.5 121.1 55.4 23.1 3.9 277.9 4.4 7 59.9 61.4 13.5 7.1 26.2 156.4 211.3 92.4 465.9 9.7 8 25.7 7 196.8.81 64.3 45.9 13.2 69.4 12.1.16 9 21.8 93.6 1 68.6 54.9 128 29 252 93 4 39 713 59 Galy and France-Lanord, 1999 11(a) 29.9 197.5 656.5 73.9 76.4 531.2 181 156.35 2874.6 169.2 Sarin et al., 1989 11(b) 124.6 183 59 462 187 59 13 1185 137 Galy and France-Lanord, 1999 12 28.4 165 51.7 8.2 111 14.6 59.2 15.3 253 51.7 13 74.5 12.2 15.3 17.3 274.6 11.1 18.2 69.2 624.4 91.8 14 1.8 13.3 7.4 3.6 3.8 5.2 8.9 SCOPE 42 - Biogeochemistry of Major World Rivers 15 39.7 228.8 47.9 17.1 159.9 52.7 18.3 78.55 266.1 17.8 Karim and Veizer, 2 16 92.3 248 598.5 23.4 114.8 113.4 235.9 23.9 92.9 76.7 17 6.3 5.3 35.4 33.6 1 6.1 57.6 SCOPE 42 - Biogeochemistry of Major World Rivers 18 36.2 11.6 29.1 3.9 141.5 55.6 9.8 28.3 34.7 26.3 Huh et al., 1998 19 6.4 24.8 24.2 3.2 13 13.7 11 1.5 63.7 8 2 54.3 34.8 85.8 6.8 231.4 87.6 58.8 95.9 468.8 13 2
21 36.9 239.2 113 15.3 117.4 42.6 119.9 47 252.9 65.7 22(a) 14.2 63.5 29.1 3.8 53.7 19.9 14.9 13.5 135.2 14.8 This study 22(b) 4.4 17.7 68.8 11.9 157.3 48.7 4.3 39.3 371 56 This study 22(c) 163.8 164 413 29.9 623.6 228.6 279.1 213.7 1436 14 23 123.1 375.6 272.5 41 484.5 28.6 167.6 151.6 184.1 72.4 24 18.1 32.2 175.6 6.2 21 28 195.4 15.8 61.6 3.3 25 9.8 49.5 12.9 4.6 22.9 12.9 4.3.8 91.1 38.7 26 48.5 73.6 282.6 25 96.9 72 157.1 67.8 356.5 26.6 27 6.1 19.1 19.7 12.4 221.8 1.2 88.7 42.5 61.1 2.5 28 66 17.8 29 2.5 144 46.3 15.9 53.1 15.6 19.5 22.75 83.5 38 Nemeth et al., 1982 3 57.3 92.6 153.8 62.6 115.2 57.3 123.2 14 459.5 189.8 31 21.2 13 6.6 3 13.6 18.6 2.1 3.95 242.1 2.8 Moon et al., 27 32 64.6 91.8 5.5 242.7 138.8 12.5 2.1 733.2 33 5.3 188.8 34 2.9 2.5 35 3.9 239.4 36 42.6 52.4 59.6 1.8 181.9 62.3 15.9 28.75 467.6 26.5 Zhang et al., 27 37 6.5 4.3 86 12.6 27 88.9 77 52.6 596.2 14.4 38 43.1 53 43.6 5.8 181.8 59.4 91 37.7 393.3 33 Varol et al., 213 39.75 2.9 4 3.4.18 6.8 SCOPE 42 - Biogeochemistry of Major World Rivers 4 183.4 472.2 295.1 53.6 733.2 314.2 146.2 16.7 1915.9 93.5 Chen et al., 22 41 16.2 887.7 72.8 13.2 36.8 36 59.3 32.95 15.9 Chen et al., 25 42 3.9 48.3 19.1 5.2 134.4 49.9 5.2 39.4 32 21.6 43 42.8 41.5 112.9 42.8 142.8 9.9 98.6 53.85 15.6 29 Meybeck, 1984 44 8.7 45.9 25.6 5.3 28.9 18.4 2.3 3.4 57.2 3.5 Sum 213.9 749.8 4862.8 778.9 749.8 3391.9 3181.4 1887.4 229.8 25.6 World total 3618.2 1261 846 124 125 523 612 26 319 648 Glay and France-Lanord, 1999 21
Fluxes are calculated by multiplying concentrations by annual discharge. 22
(e) Specific flux TDS TSS Na K Ca Mg Cl SO 4 HCO 3 SiO 2 t/km 2 /y t/km 2 /y 1 3 mol/km 2 /y 1(a) Amazon (upper) 1(b) Amazon (lower) 4.6 19 67.7 22 138 42.5 32.6 19 344.8 128 2 Amur 12 28 27.4 5.7 48.5 2.7 14.4 14.1 13.8 7.8 3 Brahmaputra 96.1 1112.7 94.3 5 362 161 32.6 156.1 811.3 134 4 Chao Phraya 68 5 Colorado 19 67 6 Columbia 49.9 22 94.2 12 195 89.4 37.3 49.9 448.2 65 7 Danube 81 83 139.8 9.6 279 211 286 124.9 629.6 13 8 Don 65.9 18 54.6 2.1 165 118 334 178.1 261.9.4 9 Fraser 91 39 1 Ganges 64.7 476.3 12.8 27 238 87.7 37.7 36.8 672.6 55.7 11(a) Ganges-Brahmaputra 127.8 668 399.6 45 463 323 11 95.2 175 13 11(b) Ganges-Brahmaputra 75.8 111.4 35.9 281.2 113.8 35.9 79.1 721.2 83.4 12 Godavari 94.6 55 172.5 27 37 48.5 198 51. 843.3 172 13 Yenisei 3.5 5 61.6 7.1 113 41.4 73.9 28.3 255.9 38 14 Indigirka 5.4 39 21.8 1.6 11.2 15.4 26.3 15 Indus 45.1 26 54.5 19 182 59.9 2.8 89.3 32.3 2 16 Irrawaddy 23.6 62 1496.3 59 287 283 59 59.7 2257 192 17 Kolyma 1.8 9 6 56.9 1.7 1.3 97.6 18 Lena 15.6 5 12.5 1.7 61 24 4.2 12.2 146.9 11 19 Limpopo 2.7 8 78 1 42.1 44.1 35.4 4.7 25.6 26 2 Mackenzie 37 23.7 58.4 4.6 157 59.6 4 65.3 318.9 8.8 21 Magdalena 142.1 92 434.6 59 451 164 461 18.6 972.7 253 23
22(a) Mekong (Chiang Saen) 75.1 336. 154.1 2 284 16 78.7 71.6 715.4 78.2 22(b) Mekong (Pakse) 74.1 313.2 126.2 22 289 89.4 73.9 72.1 68.7 13 22(c) Mekong 199.8 2 53.7 37 761 279 34 26.6 1751 127 23 Mississippi 39.3 12 87 13 155 66.7 53.5 48.4 346.4 23 24 Murray Darling 16.3 29 158.2 5.5 18.9 25.2 176 14.3 55.5 3 25 Niger 6.5 33 8.6 3.1 15.3 8.6 2.9.6 6.8 26 26 Nile 26.4 4 153.6 14 52.6 39.1 85.4 36.8 193.8 14 27 Ob 2 6.3 36.4 4.1 73.7 33.3 29.5 14.1 22.7 6.8 28 Orange 1 27 29 Orinoco 21.3 15 48.2 17 55.3 16.2 198 23.7 87 4 3 Parana 2.2 32.6 54.2 22 4.6 2.2 43.4 4.9 161.8 67 31 Red 176.3 183.4 55.4 25 863 155 17.4 32.8 217 173 32 Salween 198.7 282.4 17 747 427 371 6.5 2256 33 Sao Francisco 9 32 34 Senegal 8 7 35 Severnaia Dvina 13 798 36 Xijiang 12.9 149 169.2 31 517 177 45.1 81.7 1328 75 37 St. Lawrence 69.5 5 98.9 15 31 12 88.6 6.4 685.2 17 38 Tigris-Euphrates 46.4 57 46.9 6.2 196 63.9 97.8 4.5 422.9 36 39 Yana 3.6 14 19 16.4.9 32.6 4 Yangtze 15.4 271.4 169.6 31 421 181 84 92.4 111 54 41 Yellow 21.6 1183.6 97.1 18 49.1 48 79.1 44. 141.2 42 Yukon 39.7 62 24.5 6.7 172 63.9 6.7 5.5 387.2 28 43 Zaire 11.9 11.5 31.4 12 39.7 25.2 27.4 15. 41.8 58 44 Zambesi 6.7 35 19.6 4.1 22 14.1 15.5 2.6 43.7 23 World mean 24.4 85.1 57.1 8.4 84.4 35.3 41.3 13.9 215.3 43.7 Specific flux (areal yield) is annual flux normalized to drainage area 24
Table S5. Statistically historical trends as year for concentrations and fluxes of TSS and major ions in the Mekong River. (a) Chiang Saen Y R 2 Adjusted R 2 p Chiang Saen Observed mean (Y 1985) TSS 34982.594-17.35 * Y.62.64 <.1 Ca -23.85 +.254 * Y.117.591 Mg -16.989 +.841 * Y.334.37.2 Na -.478 +.523 * Y.3.797 K 7.976 -.36 * Y.9.647 HCO 3-267.252 +.188 * Y.4.4.34 Cl -114.647 +.621 * Y.14.11.55 SO 4-637.8 +.329 * Y.241.211.9 Si -13.12 +.545 * Y.398.365.3 Discharge-weighted mean (Y 1985) TSS 14112.367-7.494 * Y.416.343.44 Ca 455.992 -.216 * Y.153.476.263 Mg -14.933 +.738 * Y.14.321.287 Na -79.51 +.441 * Y.78.457 K 3.817 -.14 * Y.6.945 HCO 3-631.971 +.368 * Y.592.498 Cl 37.533 -.154 * Y.2.896 SO 4 768.743 -.378 * Y.231.134.16 Si -16.117 +.16 * Y.15.778 Historical discharge-weighted mean (Y 196) TSS 694.421-2.71 * Y.33.119.217 Ca 9.45 +.799 * Y.349.139.23 Mg -.15 +.292 * Y.335.125.213 Na -4.762 +.64 * Y.317.16.226 K 1.642 +.432 * Y.242.3.291 HCO 3 27.759 +.35 * Y.343.133.28 Cl -5.669 +.62 * Y.31.99.232 SO 4-5.961 +.17 * Y.328.118.218 Si 2.239 +.133 * Y.349.139.24 Annual flux (Model 2; Y 196) TSS 835.551 -.389 * Y.347.137.25 Ca 8.842 -.335 * Y.264.523.27 Mg 1.764 -.638 * Y.268.56.267 Na 2.49 -.687 * Y.261.5.272 K.638 -.247 * Y.27.58.265 HCO 3 32.859 -.123 * Y.264.53.27 Cl 1.189 -.332 * Y.166.382 SO 4 4.871 -.175 * Y.266.54.268 Si 1.651 -.622 * Y.267.56.267 25
(b) Pakse Pakse Observed mean (Y 1985) Y R 2 Adjusted R 2 TSS 1836.47-9.11 * Y.421.397 <.1 Ca 91.467 -.343 * Y.16.53 Mg -65.449 +.351 * Y.12.85.76 Na -26.855 +.167 * Y.517.727 K 13.237 -.586 * Y.92.642 HCO 3 22.581 -.6 * Y.6.71 Cl -214.332 +.111 * Y.196.164.21 SO 4-137.758 +.768 * Y.25.476 Si -13.859 +.685 * Y.26.159.51 Observed mean in the recent decade (21-211) Ca 1192.518 -.583 *Y.49.433.16 Na - 168 +.536*Y.638.62.2 HCO3 2679.242-1.294*Y.583.536.6 Cl -76.724 +.383 *Y.284.25.91 Discharge-weighted observed mean (Y 1985) TSS 2858.72-14.111 *.872.47 Y Ca -22.987 +.112 * Y.138.519.234 Mg -167.398 +.86 * Y.142.558.228 Na 33.926 -.15 * Y.262.18.17 K 39.3 -.189 * Y.187.689 HCO 3-458.762 +.268 * Y.425.52 Cl -389.942 +.199 * Y.336.269.48 SO 4-13.664 +.511 * Y.395.334.29 Si -331.721 +.169 * Y.451.39.24 Historical discharge-weighted mean (Y 1923) (modelled) Annual flux (Model 2; Y 1923) TSS 2582.962-1.51 * Y.432.315.58 Ca 9.811 +.55 * Y.72.67.14 Mg.928 +.14 * Y.714.61.14 Na -.521 +.28 * Y.749.637.12 K 1.345 +.58 * Y.74.627.12 HCO 3 36.845 +.174 * Y.717.63.14 Cl -2.799 +.372 * Y.727.614.13 SO 4.696 +.569 * Y.727.614.13 Si 3.55 +.948 * Y.732.619.13 TSS 1131.257 -.489 * Y.391.274.71 Ca 2.483 -.715 * Y.49.374.43 Mg 3.69 -.127 * Y.491.375.43 Na 4.75 -.155 * Y.491.375.43 K 1.57 -.562 * Y.483.367.45 HCO 3 75.189 -.264 * Y.49.37.43 Cl 4.631 -.147 * Y.491.375.43 SO 4 1.49 -.32 * Y.443.326.55 Si 5.571 -.198 * Y.489.373.43 p 26
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