Estimation of groundwater discharge and associated chemical fluxes into Poyang Lake, China: approaches using stable isotopes (δD and δ18O) and radon

Liao, Fu; Wang, Guangcai; Shi, Zheming; Cheng, Guoqiang; Kong, Qingmin; Mu, Wenqing; Guo, Liang

Estimation of groundwater discharge and associated chemical fluxes into Poyang Lake, China: approaches using stable isotopes (δD and δ18O) and radon | Evaluation des apports d’eaux souterraines et des flux chimiques associés dans le lac Poyang, Chine: approches utilisant les isotopes stables de la molécule d’eau (δD et δ18O) et le radon Estimación de la descarga de agua subterránea y flujos químicos asociados en el lago Poyang, China: enfoques que utilizan isótopos estables (δD and δ18O) y radón 运用氢氧稳定同位素(δD和δ18O)和氡估算地下水向鄱阳湖的排泄量及相关的化学物质通量 Estimativa da descarga de águas subterrâneas e fluxos químicos associados no Lago Poyang, China: abordagens usando isótopos estáveis (δD e δ18O) e radônio

2018

Poyang Lake is the largest freshwater lake in China and is well known for its ecological and economic importance. Understanding the contribution of groundwater to Poyang Lake is important for the lake’s protection and management. In this study, stable isotopes (δD and δ¹⁸O), ²²²Rn measurements, and corresponding models (²²²Rn and ¹⁸O mass balance models) were employed to evaluate the groundwater discharge and associated chemical inputs to Poyang Lake. The results showed that the distribution of δ¹⁸O in the lake water reflects the groundwater discharge into the lake. The groundwater discharge estimated using the ²²²Rn mass balance model was in reasonable agreement with the groundwater discharge derived from the ¹⁸O mass balance model. The ²²²Rn mass balance model showed that the groundwater discharge rate was 24.18 ± 6.85 mm/d with a groundwater discharge flux of (2.24 ± 0.63) × 10⁷ m³/d, which accounts for 6.52–11.14% of river-water input in the Poyang Lake area. The groundwater discharge flux estimated using the ¹⁸O mass balance model was 3.17 × 10⁷ m³/d, and the average groundwater discharge rate was 26.62 mm/d. The estimated groundwater discharge was used to estimate the associated chemical fluxes. It was found that groundwater-derived heavy metals such as iron and manganese are potential threats to the lake ecological system because of their large inputs from groundwater discharge.

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