1191 (2) definition of particle properties and estimation of initial sea-surface deposition locations based on wind conditions and gravitational settling; (3) numerical simulation of marine particle transport using a Lagrangian particle tracking model; and (4) visualization of the results within a three-dimensional geospatial digital twin environment. 2.2 Study area The target site is the Cerro Quemado quarry located on San Cristóbal Island, Galápagos Islands, Ecuador (approximately 0.92°S, 89.61°W). The quarry is situated within several kilometres of the coastline, allowing particulate matter generated during quarrying operations to potentially reach adjacent coastal waters through atmospheric transport and deposition. The island is influenced by trade-wind-driven atmospheric circulation and seasonally varying ocean currents associated with the Humboldt Current system and the Equatorial Countercurrent, making it suitable for investigating coupled land–sea dispersion processes. 2.3 Seasonal classification and dataset The seasonal classification in this study follows the criteria based on the annual cycle of sea surface temperature in the eastern equatorial Pacific (Hayes et al., 1989), and incorporates the refined definitions (Hartten & Datulayta, 2004). Atmospheric conditions were analyzed using the ERA5 reanalysis dataset provided by the European Centre for Medium-Range Weather Forecasts (ECMWF). Hourly wind speed and wind direction at 10 m above the surface were extracted for 2020–2024 from four grid cells surrounding the quarry site (longitude/latitude: −89.75, −1.00; −89.50, −1.00; −89.75, −0.75; −89.50, −0.75). To reflect emission timing, the analysis was limited to quarry operating hours (16:00–20:00 UTC; 10:00–14:00 local Galápagos time, UTC−6). 2.4 Particle characteristics and atmospheric transport scenario This section describes the input parameters used in the simulations and the methodology for estimating particle transport distances. Particles generated at the Cerro Quemado quarry originate from mechanical processes such as excavation and crushing (Dueñas Tovar et al., 2024). Based on previous studies, PM10 particles, which are considered the dominant component in long-range transport, and 30μm particles as a comparative case were selected for analysis (Sirianni et al., 2008). Particle density was determined by considering the physical properties of porous scoria and basaltic lava, including porosity (AlHarthi et al., 1999)(Hornby et al., 2020). Previous studies have reported porosities of vesicular basalt ranging from 15% to 29%, with an average of 22% (Nabawy & Wassif, 2017). Accordingly, in this study, the porosity was assumed to be 20%, and the apparent particle density was set to 2,400 kg m⁻³. The air density was set to 1.2 kg m⁻³, and the effective release height was defined as 60 m based on the local topography of the quarry. The gravitational settling velocity, ¡E, was calculated assuming spherical particles and laminar flow conditions, using Stokes’ law as follows (Stokes, 1851). vs= gçρp- ρféD2 18μ (1) where “g” is the gravitational acceleration, “ρp” is the particle density, “ρf” is the air density, “D” is the particle diameter, and “μ” is the dynamic viscosity of air. Based on the calculated settling velocity and wind conditions, the theoretical horizontal transport distance of the particles until they reach the sea surface was estimated.
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