Qualitative risk aggregation problems for the safety of multiple aquifers exposed to nitrate, fluoride and arsenic contaminants by a ‘Total Information Management’ framework

Abstract

The aquifer at Varzeqan plain, with multiple confined/unconfined and hard-rock boundaries, is exposed to risks from several contaminants (nitrate-N, fluoride and arsenic) originated by anthropogenic and/or geogenic activities, which are possibly accelerating by anthropogenic activities. The study is a research initiative driven by impacts of poor or non-existent planning/ regulation practices to produce insights despite the sparsity of the available data and the unknown baseline. A methodology is given, which seeks ‘total information management’ by pooling together the following five dimensions: (i) a perceptual model to collect existing knowledge-base; (ii) a conceptual model to analyse a sample of ion-concentrations by a set of existing techniques (e.g. statistical, graphical and multivariate analysis); (iii) risk cells to contextualise each contaminant; (iv) “soft modelling” to firm up information by learning from convergences and/or divergences within the conceptual model; and (v) study the processes within each risk cell through the OSPRC framework (Origins, Sources, Pathways, Receptors and Consequence). The research caters for inherent variabilities in the study area by 15 risk cells delineated within the boundaries of confined, unconfined and hard-rock aquifers as follows: 4 risk cells account for minor ions of nitrate-N pollution of anthropogenic origins; 6 for minor ions of fluoride and 5 for trace ions of geogenic arsenic anomalies. It further identifies the possibility of anthropogenic activities encouraging geogenic anomalies. The findings are presented as a descriptive model but this will be transformed into quantitative models in due course when more data become available.