CHEMICAL WEATHERING PROCESSES AND ATMOSPHERIC CO_2 CONSUMPTION IN THE YELLOW RIVER DRAINAGE BASIN

According to the correlation and principal composition analysis of the Yellow River water, the water chemistry is mainly controlled by the weathering processes of carbonates and evaporites,which are responsible for about 75% of total ion equivalent concentration. Around 10% of the dissolved load is imported in the form of HCO3- from the atmospheric CO2, while the silicate weathering input may have a contribution of only 754% of the total dissolved flux into the Yellow River water. The results suggest that no pronounced effect of silicate weathering on the Yellow River chemistry is found. The analysis of the composition loadings shows that 90% of HCO3- concentration originates from the carbonate weathering reactions, while only 10% is derived from silicate dissolution. The weathering rate is estimated at 336 t/km2.a deduced from HCO3- concentration from atmospheric CO2, close to the world average. The CO2 consumption rate by rock weathering amounts to 143.85×103 mol/km2 for the Yellow River basin annually, 40% lower than the world average level. The quantity of CO2 consumption sink is equal to 108×109 mol yearly, 818% from carbonate weathering and 182% from silicate weathering Compared with other world watersheds, the higher evaporite content and infirm silicate dissolution may result in the lower CO2 consumption rate and wastage budget in the Yellow River drainage basin.