Geostatistics as a tool to improve the natural background level definition: An application in groundwater

摘要: Abstract The Natural Background Level (NBL), suggested by UE BRIDGE project, is suited for spatially distributed datasets providing a regional value that could be higher than the Threshold Value (TV) set every country. In hydro-geochemically dis-homogeneous areas, use of unique NBL, TV, arise problems to distinguish between natural occurrences and anthropogenic contaminant sources. Hence, goal this study improve NBL definition employing geostatistical approach, which reconstructs spatial structure accounting geochemical hydrogeological relationships. This integrated mapping fundamental evaluate contaminant's distribution impact on giving indications it. We decided test method Drainage Basin Venice Lagoon (DBVL, NE Italy), where existing seven times TV. area notoriously affected naturally occurring arsenic contamination. An available dataset collected 50 piezometers was used reconstruct in densely populated DBVL. A cokriging approach applied exploiting relationships among As, Fe NH4 +. obtained predictions concentrations were divided into three different zones: i) areas with an As concentration lower ii) TV median values iii) median. Following suggestions, enough samples available, 90th percentile each zone calculated obtain local (LNBL). Differently from original gives more detailed water quality information setting, variation. LNBL give about distinction occurrence