A Spatiotemporal Analysis of Nitrogen Pollution in a Coastal Region with Mangroves of the Southern Gulf of Mexico

Abstract

Nitrogen pollution is a growing problem in many rivers and estuaries of the Southern Gulf of Mexico. In Costa Esmeralda, a tourist destination in Veracruz, the increasing nitrogen pollution is causing severe environmental damage. However, very few studies addressed nitrogen pollution and its consequences for beaches and mangroves. In this study, a spatiotemporal evaluation of nitrogen concentrations was performed along two rivers discharging into Costa Esmeralda and the associated mangrove and coastal areas. The data used was obtained from the local government, which measured ammonium, nitrate and organic nitrogen concentrations between 2013 and 2016 with four annual measurements. Clustering analysis was used to detect the nitrogen concentration differences between riverine and coastal sites. Additionally, Mann-Kendall test was used to detect the trends throughout the study period. The Mann-Whitney W-test determined the difference in the median concentrations between the dry and the wet season. The results indicate that organic nitrogen concentrations are increasing in river mouths and coastal waters. Nitrogen pollution caused an intrusion of water hyacinths in touristic beaches and completely covered mangroves. The decomposition of these plants in saline waters was identified as the main potential source of increasing organic concentrations, driven by nitrogen pollution from wastewater, deforestation and fertilizers, and causing many environmental and socio-economic damage to the area. The results shed light on the prevailing water pollution problems in the Southern Gulf of Mexico.

Using grey clustering to evaluate nitrogen pollution in estuaries with limited data

“…All monitoring sites were placed in the same class by the GNMP and the GLUP indexes, indicating that land use pressures were detected accurately. The results indicate that Nautla and Tuxpan estuaries have the highest urgency for N pollution management which agrees with previous studies which indicated the existence of N pollution in these estuaries (González-Marín et al, 2017;Marín-Muñiz et al, 2016;Rivera-Guzmán et al, 2014;Rodríguez-Romero et al, 2018;Temino-Boes et al, 2019). Studies in Nautla river indicated that human settlements are a major source of N pollution to the river at its lower course (Rodríguez- Romero et al, 2018).…”

“…The aim of our approach is to evaluate the pollution within the estuary to estimate the potential consequences of nitrogen pollution to the surrounding ecosystems such as beaches or mangroves. For example, the consequences of nitrogen pollution in Nautla estuary include the degradation of touristic beaches with consequences for the local economy, as well as the deterioration of mangroves (Temino-Boes et al, 2019). But the impact of high nitrogen concentrations in Papaloapan river in the eutrophication of the Gulf of Mexico as a whole would be much worse than N pollution in Actopan river.…”

“…Approximately 27% of the state population lives within 20 km of the coast (Macauley et al, 2007). The estuaries in Veracruz have been affected by nutrient enrichment for decades (Macauley et al, 2007;Temino-Boes et al, 2019), but agriculture, urbanization and other economic activities such as tourism along the coast are still a grown source of water pollution (Adame et al, 2018;Rivera-Guzmán et al, 2014). The Mexican legislation does not regulate nitrogen emissions to natural water bodies, and no data exist on direct inputs from urban or industrial sources.…”

“…The Mexican legislation does not regulate nitrogen emissions to natural water bodies, and no data exist on direct inputs from urban or industrial sources. Nonetheless, nitrogen pollution has dramatic consequences for mangroves in estuaries, and it allows the massive intrusion of water hyacinths into beaches and mangroves (Temino-Boes et al, 2019). Clearly, management decisions need to be taken as soon as possible to set remediation plans and avoid further deterioration.…”

“…Water pollution evaluation has always relied on spatiotemporal analysis (Ali et al, 2016;Hajigholizadeh and Melesse, 2017;Temino-Boes et al, 2019). As such, a good water pollution evaluation should consider both spatial and temporal variations of water quality, which should be reflected when developing a classification method (Li et al, 2016).…”