The advection-diffusion of pollutants in a complex coastal lagoon influenced by agricultural and aquaculture effluents in the southeast Gulf of California

Abstract

Understanding hydrodynamic processes is crucial for examining the transport of living biomass and contaminants, including nutrients, metals, persistent organic pollutants, plastics, and suspended particles in aquatic systems. This study investigates pollution transport and influence times in the Altata-Ensenada del Pabellón (ALENPA) coastal lagoon in northwest Mexico using a vertically integrated hydrodynamic model and advection-diffusion equations. When tidal forces, freshwater discharge, and wind effects were taken into account in numerical simulations of a passive tracer release, the effect times ranged from a few weeks near the inlet to over four months in the eastern lagoon. The Culiacan River discharge and prevailing northwest winds significantly impacted these times and their spatial distribution, with areas in the southern lagoon showing slower tracer dispersion, suggesting higher vulnerability to pollution. This investigation provides insights into the hydrodynamic environment of the ALENPA lagoon, identifying regions with long and short influence times based on specific meteorological and hydrological conditions. More broadly, it enhances our understanding of pollutant transport in coastal environments, offering a valuable tool—the numerical assessment of ITD—for selecting suitable, less vulnerable sites for aquaculture or waste disposal across diverse coastal lagoons.

Keywords

• Influence times
• Hypothetical tracer
• Pollutant dispersion
• Numerical model
• Gulf of California