This study aimed to understand the spatiotemporal variation of nutrient concentrations in stream water, using analyses of total nitrogen (TN), NO₃⁻-N, NH₄⁺-N and total phosphorus (TP) concentrations from April to October in 2016 in the upper Shule River basin in the northeastern margin of the Qinghai-Tibetan Plateau. Dissolved inorganic nitrogen (DIN; NO₃⁻-N + NH₄⁺-N) concentrations in both groundwater and stream water were the predominant form of TN, accounting for about 88%. Median concentrations in stream water were 815 μg L⁻¹ for TN, 459 μg L⁻¹ for NO₃⁻-N, 253 μg L⁻¹ for NH₄⁺-N, and 25 μg L⁻¹ for TP. Great spatiotemporal variations of nitrogen and phosphorus concentrations in stream water were observed, which likely resulted from varying recharge sources (snow and groundwater) and biogeochemical processes. Monthly variations in nutrient concentrations in stream water had a reciprocal pattern between nitrogen and phosphorus concentrations. Our results demonstrated that the quality of steam water in the upper reach of Shule River basin was basically good for drinking purposes according to the environmental quality standards for surface water, China. The results also improved our understanding of how nutrient concentrations varied in stream water and provided baseline information for future studies on nutrients in the Qinghai-Tibetan Plateau.

The delivery of suspended sediment by rivers to the downstream ecosystem represents an important pathway in the geochemical cycle, a key component of the exfoliation system, and an important estimation of land degradation and the associated reduction in soil resource. In order to understand the suspended sediment transport variation in the Dongkemadi River catchment of the Tibetan Plateau and determine its relationship with discharge, daily discharge data and suspended sediment samples were collected and data were analyzed from June to September in 2013. Daily mean Suspended sediment concentrations (SSC) in the stream ranged from 0.1 to 668.2mg/L. The mean daily SSC for the entire sampling period was computed to be 107.6 mg/L. Daily suspended sediment load (SSL) varied from 2 to 409.5 tones·day^-1 at the gauging site. The mean daily total suspended loads for the observing season was computed to be 68 tones. The daily discharge had a good relationship with daily suspended sediment concentrations. The relationship between SSC and discharge was mainly characterized by clockwise hysteresis. This study provides insight into the relation between suspended sediment and discharge with daily data in summer in the high elevation cold regions of the Tibetan Plateau.