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.
The anthropogenic alteration of the nitrogen cycle results in the modification of the whole food web. And yet, the impact caused on nitrogen dynamics in marine systems is still very uncertain. We propose a workflow to evaluate changes to coastal nitrification by modelling nitrite dynamics, the intermediary compound. Nitrite concentrations were estimated with a simple steady state nitrification model, which was calibrated in 9 NW Mediterranean coastal sites with different anthropogenic pressures, located within 250km. The results obtained indicate that nitrite peaks are observed in winter and explained by nitrification response to temperature, but these dynamics are altered in impacted coastal waters. We found the second step of nitrification to be more sensitive to temperature, which entails a significant impact of climate change on the decoupling of the two steps of nitrification. The results could be extrapolated to numerous coastal regions of the Mediterranean Sea with similar characteristics.
The European Water Framework Directive aims to achieve a good status of all inland and coastal waters in the European Union by evaluating the status and the anthropogenic pressures to natural water bodies. As such, several techniques have been developed to evaluate the anthropogenic pressure to coastal areas. The most widespread methods are indexes, although some authors have also used the application of models. Using indexes has many advantages, such as the simplicity or the fast application. The anthropogenic pressure is generally assessed through the application of an index which is calculated based on parameters such as population density, urbanization, industry, agriculture, fisheries and maritime transport. However, the dispersion of contaminants along the coast is a factor that is generally overlooked by such indexes. Natural coastal waters have been widely assessed in Member States. On the contrary, heavily modified coastal waters, which are generally located close to the biggest urban areas, have been left aside in the evaluation process. To demonstrate that minimizing pollution in heavily modified coastal waters is a must, we evaluated several nutrient concentrations in natural coastal waters of the Jucar River Basin District, located in the Western Mediterranean Sea (Spain). We calculated the correlation between nutrient concentrations and several anthropogenic pressures, including the presence of adjacent water bodies considered as heavily modified by human activity under the Water Framework Directive. Then, a forward stepwise linear regression was applied to identify the activities most affecting nutrient concentrations. It was found that the presence of a neighbouring water body classified as heavily modified was the main driver of nutrient concentration differences among natural water bodies. These results suggest that the evaluation of anthropogenic pressures to coastal waters should also consider the dispersion of pollutants from adjacent heavily modified coastal waters.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.