Seasonal changes in the radiogenic and stable strontium isotopic composition of Xijiang River water: Implications for chemical weathering

Tracing Sr isotopic composition in space and time across the Yangtze River basin

“…Consequently sampling at a single time slice of any season would lead to errors in estimates of average values and total fluxes of 87 Sr/ 86 Sr. Time-series observations of several Tibetan rivers record a seasonal variation in dissolved 87 Sr/ 86 Sr, with lower 87 Sr/ 86 Sr ratios occurring during the monsoon as a result of enhanced carbonate weathering (Tipper et al, 2006;Rai and Singh, 2007;. However, unlike rivers from the Himalaya, Wei et al (2013) found higher 87 Sr/ 86 Sr values during high discharge season in the Xijiang River in south China, indicating enhanced silicate weathering during rainy seasons. In the absence of accurate spatial and temporal characterization of the river basin, it is not possible to judge what causes the discrepancy.…”

“…However, Bickle et al (2003) and Voss et al (2014) suggest that changing inputs of weathered material and solutes from different lithotectonic units, because of spatially uneven rainfall, contributes to seasonal variations in 87 Sr/ 86 Sr ratio. Wei et al (2013) attributed the higher 87 Sr/ 86 Sr ratios in the Xijiang River during intervals of high discharge to the enhanced weathering of silicates during rainy seasons. With no clear differences in 87 Sr/ 86 Sr between wet and dry season, the data in the present study raise a series of questions about the mechanisms controlling the temporal variation of 87 Sr/ 86 Sr ratios in the Yangtze River.…”

Isotope Fractionation Processes of Selected Elements

“…By analysing Sr dissolved in rivers, the behaviour of 88/86 Sr during weathering has been investigated (Krabbenhöft et al 2010;de Souza et al 2010;Wei et al 2013). Krabbenhöft et al (2010) demonstrated that large rivers are quite variable in δ 88 Sr.…”

“…De Souza et al (2010) concluded that Sr released during weathering of silicate rocks does not indicate any Sr-isotope fractionation. By analyzing a river from South China, large seasonal Sr-isotope differences depend on the amount of precipitation (Wei et al 2013).…”

Chemical weathering controls on variations in the molybdenum isotopic composition of river water: Evidence from large rivers in China

“…The XJR is the main tributary of the Pearl River, the 2th largest river in China after the CJR in terms of discharge, and covers 77.8% of the drainage area and provides 63.9% of the discharge of the Pearl River (Wei et al, 2013;Zhang et al, 2007). The XJR originates in the Maxiong Mountains in Yunnan Province and passes through Guizhou, Guangxi, and Guangdong provinces before entering the South China Sea through the Pearl River Delta in Guangdong Province (Zhang et al, 2007;Fig.…”