Rates of hydroxyapatite formation and dissolution in a sandstone aquifer: Implications for understanding dynamic phosphate behaviour within an agricultural catchment

Application of Remodeled Water Quality Indices and Multivariate Statistical Methods for the Appraisal of Water Quality in a Himalayan Lake

“…The limiting nutrient which leads to the eutrophication of fresh water systems is phosphorus (Rabalais., 2002;Vyas et al, 2006;Zhang et al, 2019). Dissolution of phosphate rocks and (apatite) weathering of minerals are considered to be the main source of phosphorus (Bingham et al, 2020). The concentration of TP in the current study was higher at each station and were well above the eutrophication control limit value (0.02mg/l) (Salade et al, 1997; wang and liang., 2015) the value has increased signi cantly according the ndings of (Mushtaq et al, 2018) based on data from 2015.…”

Geochemical cycling in aquifers contributes to the transport, storage and transfer of anthropogenically-derived phosphorus to surface waters

“…In Bingham et al (2020) we used a continuous flow-through reactor to experimentally determine mineral dissolution rates of HAP at various pH, P and Ca concentrations, from which we derived a dissolution rate constant for HAP. The rate constant was then used in a 1D reactive transport model (Geochemist's Workbench ® Professional v.12 software, Bethke et al, 2018, with the Thermo database, Daveler and Wolery, 1992) to understand HAP mineral dissolution and precipitation reactions and rates over time during downward transport in a sandstone aquifer as functions of groundwater chemistry and flow rate.…”

“…In the present study, the concentration of baseflow phosphorus entering the headwaters of the Hampshire Avon was quantified using a 2D reactive transport model. Briefly, 1D reactive transport models (as per Bingham et al, 2020), representing conditions at 25 points near the East Avon and West Avon, were linked to the Wessex Basin groundwater model (Soley et al, 2012) to estimate mineral-derived P fluxes along 2D transects parallel to groundwater flow paths and concentrations of mineral-derived P along the rivers over 120-days intervals. HAP and CFA dissolution and precipitation reactions were modelled using rate constants from Bingham et al (2020) and Guidry and Mackenzie, 2003, respectively.…”

“…Briefly, 1D reactive transport models (as per Bingham et al, 2020), representing conditions at 25 points near the East Avon and West Avon, were linked to the Wessex Basin groundwater model (Soley et al, 2012) to estimate mineral-derived P fluxes along 2D transects parallel to groundwater flow paths and concentrations of mineral-derived P along the rivers over 120-days intervals. HAP and CFA dissolution and precipitation reactions were modelled using rate constants from Bingham et al (2020) and Guidry and Mackenzie, 2003, respectively. The 2D models incorporated data from the UGS stratigraphy (Section 2.3.1) to constrain the zones of CFA occurrence, and the chemical analysis of the extracted porewaters (Section 2.4.1) and bulk rock (Section 2.4.2) to estimate the mass of apatite minerals in the stratigraphic layers.…”

“…Laboratory and modelling studies suggest that HAP is chemically less stable and more soluble compared to FAP and CFA, and that it can dissolve in acidic aqueous solutions (Dorozhkin, 2012;Tõnsuaadu et al, 2012;Aljerf and Choukaife, 2017). In the same context, recent research demonstrates experimentally that in presence of Ca and P at a ~2:1 ratio in a de-ionised water solution with quartz grains, it is feasible for HAP to precipitate and dissolve very rapidly at pH > 7 and pH < 7, respectively (Bingham et al, 2020).…”