Long-term monitoring programs to assess environmental pressures on coastal area: Weighted indexes and statistical elaboration as handy tools for decision-makers

Data generated by long-term monitoring programs for coastal areas are intricate and require advanced tools able to identify the factors, natural or anthropogenic, responsible for the observed quality status. In the present study, data stemming from a 5-year monitoring programme of the Apulian coast were utilized for validating a speedy and comprehensive approach to assess the environmental quality of the marine-coastal area. Selecting 12 indicator contaminants controlling the pollution degree of the bottom sediments and attributing to each of them a weighted relevance according to their hazard potential, two multimetric indexes were calculated, helping to establish how and to what extent the selected contaminants could affect the achievement of good chemical and ecological status of coastal area. The relationships between calculated hazard degree values and the main natural factors loading on the study area were addressed through multivariate analyses. The variability of hazard degree values over time was explained by means of combined use of multivariate analyses and multimetric indexes, affording a handy method that allows to differentiate the role of natural factors, such as hydrodynamic and morphological features of the coastal track versus that of anthropogenic pressures. The combined approach adopted supports a reliable hazard assessment at long-term period and at a large spatial scale.