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To systematically study chemical weathering in the entire Huanghe River basin, we divided the basin into three parts with significant differences in geology and climate. We collected 38 water samples from the main channel and its main tributaries, spread between the upstream (above Lanzhou), midstream (from Lanzhou to Huayuankou) and downstream (from Huayuankou up to river mouth) segments of the river. The concentrations of major elements and H, O isotopic compositions were obtained from the samples, and the total dissolved solids (TDS) and, CO 2 consumption budget were calculated from the aggregated data of each of the three segments. The results demonstrate that: the TDS are mainly derived from carbonate weathering in upper Huanghe River; evaporite dissolution is predominately occurred in the midstream; and there is almost no additional contribution from rock weathering in the downstream. An increasing trend of CO 2 consumption rate by silicate weathering is observed, from 0.14 × 10 5 mol/km 2 /yr in the upstream to 5.62 × 10 5 mol/km 2 /yr in the downstream, and the budget of CO 2 consumption by silicate weathering is estimated to be 26.2 × 10 9 mol/yr. In contrast, the CO 2 consumption rate by carbonate weathering decreases from 3.04 × 10 5 mol/km 2 /yr in the upstream to near zero in the downstream, and the budget of CO 2 consumption is estimated to be 100.5 × 10 9 mol/yr. As a whole, in the entire Huanghe River basin, the CO 2 consumption budget and TDS yield are estimated to be 126.7 × 10 9 mol/yr, and 27.5 × 10 6 t/yr, respectively. These results indicate that evaporite dissolution in the midstream is responsible for the high TDS in the Huanghe River basin, while carbonate weathering in the upstream plays the most significant role in CO 2 consumption. [ABSTRACT FROM AUTHOR]