Abstract
The movement of high-arsenic (As)-concentration Beitou geothermal spring water up to 4600μg/L from the upstream area may affect the downstream Guandu plain and Guandu wetland. The major As pathway is via the subsurface flow. The study assesses the fate and transport of As-enriched geothermal spring water in the Beitou-Guandu area. The groundwater head and flow field velocity are first simulated by using HYDROGEOCHEM-fluid flow model. The steady state flow field is well-calibrated with root mean square error 1.73m and R2 = 0.992. The spatial-temporal distributions of As in the Beitou-Guandu area are simulated by the HYDROGEOCHEM reactive transport model using the calibrated steady state flow field. The results show that high As concentration (250μg/L) in groundwater of Guandu plain was caused by the movement of high As concentration from the Beitou geothermal spring water. In contrast, the low As concentration (5-50μg/L) in Guandu wetland was mitigated by the tidal water dilution. The simulated As concentrations increase in the first 3years, and then gradually decrease due to the adsorption of As on the iron oxide minerals ferrihydrite and iron sulfide minerals pyrite. Furthermore, the hydrogeochemical transport model is applied to assess the effect of bioaccumulation of As by the mangrove plants of Guandu wetland. The dominant mangrove plants, Kandelia obovata, can reduce about 5-30μg/L As concentration in groundwater. It may be one of sinks of As in Guandu wetland. The inclusion of K. obovata can uptake the aqueous As and allow the simulated As concentration further close to the field measurement in the Guandu wetland. The study successfully models the reactive chemical transport of As by considering both geochemical reactions and biochemical uptakes in the Beitou-Guandu area. The result demonstrates that the complex biogeochemical transport can be quantified by the sophisticated HYDROGEOCHEM model. Moreover, the salient features of the biogeochemical reactions can be recovered and elucidated through a series of systematic simulation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.