Abstract: To elucidate how the water-sediment controlling process affects element cycling in the Yellow River Basin, water samples were collected during water-sediment controlling in 2012, and then sulfur and oxygen isotopes were analyzed. The results showed that sulfur and oxygen isotope values of river water samples in Sanmenxia station varied from 7.9‰ to 12.5‰ (with an average of 10.1‰) and from 4.8‰ to 8.4‰ (with an average of 7.1‰), respectively. Sulfur and oxygen isotope values of river water samples in Xiaolangdi station ranged from 8.5‰ to 9.1‰ (with an average of 8.6‰) and from 5.6‰ to 7.4‰ (with an average of 6.6‰), respectively. Sulfur and oxygen isotope values of river water samples in Huayuankou station varied from 8.7‰ to 12.0‰ (with an average of 10.0‰) and from 6.5‰ to 8.5‰ (with an average of 7.7‰), respectively. Sulfur and oxygen isotope values of sulfate in river water decreased with the increases of siltcontents in the river water samples, indicating that the “newly produced sulfate” was mainlyderived from oxidation of sulfide and organic sulfur during water-sediment controlling, especially in Sanmenxia station and Xiaolangdi station. However, such differences of sulfate isotopes were not significant in Huayuankou station due to the mixing processes impacted by the tributaries of Yiluo River and Qinhe River. The range of sulfate isotopes suggested that dissolved sulfate in river water was mainly controlled by dissolution of gypsum, oxidation of sulfide and organic sulfur and sewage water. Watersediment controlling process affected sulfur cycling in Yellow River, in that it can release sulfate by oxidation of sulfide and organic sulfur in sediment, and thus increases sulfate flux to the downstream. The proportion of sulfate released into river by water sedimentcontrolling was about 24.2% in Sanmenxia Reservoir and 8.8% in Xiaolangdi Reservoir, respectively. The results improved our understanding of water-sediment controlling on the riverineelement cycling in the Yellow River Basin.

Key words: dryland, winter wheat, straw retention, yield, soil fertility, plastic film mulching, planting green manure