Assessment of chloride natural background levels by applying statistical approaches. Analyses of European coastal aquifers in different environments

• Autor(a) principal: Pulido-Velazquez, D.
• Data de Publicação: 2022
• Outros Autores: Baena-Ruiz, L., Fernandes, Judite, Arnó, Georgina, Hinsby, Klaus, Voutchkova, D. D., Hansen, B., Retike, I., Bikse, J., Collados-Lara, A. J., Camps, V., Morel, I., Grima-Olmedo, J., Luque-Espinar, J. A.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.9/3857
• topic: Natural background level; Chlorides; Saltwater intrusion; Coastal aquifers; Environmental monitoring; European pilots

ABSTRACT: Estimated natural background levels (NBLs) are needed to assess groundwater chemical status according to the EU Groundwater Directive. They are commonly derived for different substances by applying statistical methodologies. Due to the complexity of the sea water intrusion process, some of those methods do not always provide appropriate assessment of chloride NBLs. This paper analyzes the applicability of different NBL estimation methods in five EU coastal aquifers with significant differences in available datasets and hydrogeological set-tings. A sensitivity analysis of results to different constraints was performed to remove samples with anthro-pogenic impacts. A novel statistical approach combining different methods to identify the range of chloride NBLs is proposed. In all pilots the estimated NBLs were below 85 mg/L and fitted well with previous studies and expert judgment, except Campina del Faro aquifer (the maximum being 167.5 mg/L). Although this approach is more time consuming, it provides a more robust solution.