1. The nonanthropogenic SO 4 in the Changjiang River stems from weathering and oxidation of sulphate and sulphite minerals, while the anthropogenic SO4 here is attributed to acid rain containing H2SO4 formed by atmospheric sulphur oxides derived from the burning of fossil fuels in the region of the lower reaches . Ca and Mg are probably derived from weathering of carbonate minerals , but possibly less from weathering of silicate minerals .2.The Changjiang River estuary is characterized by two-layer flow based on the salinity section of the estuary ,so a model of two-layer exchange of water-body in the Changjiang River estuary can be advanced .3. The presence of SO4 and K. at stations H 14 and H 15 were found most likely to be due to the addition and removal processes , that of the other major constituents may be mainly controlled by physical mixing in this estuary . 1. The nonanthropogenic SO 4 in the Changjiang River stems from weathering and oxidation of sulphate and sulphite minerals, while the anthropogenic SO 4 here is attributed to acid rain containing H2SO4 formed by atmospheric sulfur oxides derived from the burning of fossil fuels in the region of the lower reaches. Ca and Mg are probably derived from weathering of carbonate minerals, but less from weathering of silicate minerals. 2. The Changjiang River estuary is characterized by two-layer flow based on the salinity section of the estuary, so a model of two-layer exchange of water-body in the Changjiang River estuary can be advanced .3. The presence of SO4 and K. at stations H 14 and H 15 were found most likely to be due to the addition and removal processes, that of the other major constituents may be mainly controlled by physical mixing in this estuary.