关键词: 沙颍河, 水化学, 氢氧同位素, 人为输入, 淮河

Abstract: Hydrochemical compositions of river water have been profoundly altered by anthropogenic inputs, resulting in increased ion fluxes to the ocean and affecting the global material cycling. Identifying the pathways and ranges of anthropogenic contributions to river water is important for quantifying the influences of anthropogenic activities on global material cycling. Shaying River is the largest tributary in the upstream of Huai River, which has been seriously disturbed by anthropogenic inputs for a long time. Hence, it was a suitable place to examine the variations of riverine material fluxes caused by anthropogenic activities. The results would shed light on the related processes and impacts of anthropogenic input on hydrochemical compositions of riverwater. A total of 41 samples of river water and 12 samples of groundwater  were collected in December 2019 (a normal period of water level). Hydrochemical compositions and water isotope values were analyzed, with the aim to elucidate the pathways, ranges and spatial distributions of anthropogenic inputs, and to constrain the controlling factors in the Shaying River Basin. Theresults showed that major anion and cation in most river water and groundwater was bicarbonate (HCO₃^-) and calcium (Ca²⁺), respectively, and that chloride (Cl^-) and sodium (Na⁺) was dominated anion and cation in the downstream of Shaying River, respectively. The chemical weathering of carbonate and silicate, industrial wastewater and sewage, and agricultural non-point pollution sources were identified as the main factors controlling hydrochemical compositions of water. Most of Sha River water and the upstream water of the Ying River were primarily controlled by rock chemical weathering, and less affected by industrial wastewater and sewage. However, the whole Jialu River and the mainstream of Shaying River were heavily affected by industrial wastewater and sewage. Most groundwater was also influenced by agricultural nopoint pollution sources. The chloride-alkali index was less than zero because of the exchange betweenadsorbed sodium, potassium cations in silicate and dissolved calcium, magnesium cations in the local groundwater, rendering more released Na⁺ and K⁺ in the groundwater. However, the higher Na⁺ and K⁺ concentrations in river water than those in groundwater, which were mainly sourced from industrial wastewater and sewage inputs rather than from groundwater inputs. Decreased concentrations of conservative Cl^- along the Shaying River mainstream was resulted from the discharge of groundwater with low Cl^- concentrations and dilution by downstream damed river water. The dexcess values became more positive, indicating extensive water evaporation of downstream river water. Our results confirmed the effects of anthropogenic input on river water and provided a profound theoretical footstone for further water pollution treatment

Key words: Shaying River, hydrochemical composition, hydrogen and oxygen isotopes, anthropogenic input, Huai River.