Ocean Acidification around the UK and Ireland

The average atmospheric carbon dioxide (CO2) concentration exceeded 414 parts per million (ppm) in 2021, a 49 % increase above pre-industrial levels, and increasing on average by 2.4 ppm per year over the past decade (Friedlingstein et al., 2022). This ongoing increase is primarily due to CO2 release by fossil fuel combustion, cement production and land-use change (mainly deforestation) (Friedlingstein et al., 2022; IPCC, 2021). Over a quarter of this annual anthropogenic CO2 emission dissolves into the Earth’s oceans each year (fossil fuel CO2 emissions = 9.5 ± 0.5 gigatonnes of carbon per year (Gt C yr-1, 1 Gt = one thousand million tonnes)), Land-use change emissions = 1.1 ± 0.7 Gt C yr-1, ocean uptake = 2.8 ± 0.4 Gt C yr-1; Friedlingstein et al., 2022). Once dissolved, the CO2 no longer influences the atmospheric heat budget, so this oceanic uptake mitigates human-driven warming and climate change. However, dissolved (or aqueous) CO2 undergoes a chemical reaction that releases hydrogen ions (H+), thereby decreasing the seawater’s pH (Figure 1). As pH declines, the carbonate ion concentration ([CO32−] also declines (Figure 1). The [CO32−] controls the saturation state (Ω) of calcium carbonate (CaCO3) minerals such as aragonite (ΩArag) and calcite (ΩCal), and indicates the ability of these minerals to precipitate (form) or dissolve. At Ω >1 water is supersaturated with Ca2+ and CO32− ions allowing CaCO3 minerals to form. When Ω <1, seawater is undersaturated with Ca2+ and CO32− ions and therefore any exposed CaCO3 minerals are prone to dissolution. These collective changes in marine carbonate chemistry are known as ‘ocean acidification’

Develop Boltzmann equation to simulate non-Newtonian magneto-hydrodynamic nanofluid flow using power law magnetic Reynolds number

The single relaxation D2Q9 lattice Boltzmann method (LBM) is run in the current research beside the generalized power law model for simulation of non‐Newtonian magneto‐hydrodynamics (MHD) laminar flow field inside a channel with local symmetric constriction. Analytical results of non‐Newtonian fluid flow in a channel without magnetic field, as well as Newtonian fluid flow at various Hartmann No., are used to validate the numerical model. Then, fluid flow simulation is performed for non‐Newtonian fluid with different power law index at various Hartmann No. (Ha ) whereas Reynolds No. are set to be constant in all cases. The present non‐Newtonian fluid can be achieved by adding various nanoparticles such as MWCNT to the base fluid. To explore the effect of magnetic Reynolds No. (Re m ), the fluid flows with different magnetic resistivity are also simulated. Results show that the separation can be controlled by a magnetic field with the penalty of larger friction coefficient and pressure loss along the channel length. In fact, for a specified Re m , the higher the Ha , the larger the pressure loss. It is also observed that the pressure loss is larger for fluids flow with higher power law index and lower Re_m