GuEstNBL: The Software for the Guided Estimation of the Natural Background Levels of the Aquifers

Abstract

Natural background levels (NBLs) for targeted chemical elements characterize a specific groundwater body, the knowledge of which represents a fundamental information for environmental agencies responsible for the protection, management, and remediation of territory. The large number of areas subject to strong anthropogenic pressures of a different nature and magnitude makes the job of control authorities particularly difficult. The process to distinguish effective anthropogenic contamination from natural conditions and to define realistic environmental clean-up goals goes through the computation of several mutually dependent statistical methods, some of which have non-trivial resolution and interpretation. In this study, we presented a new tool designed to drive those working in the sector into an articulated path towards NBL assessment. The application software was developed in order to read environmental input data provided by a user-friendly web-based geographic information system (GIS) and to return the NBL estimate of a given chemical element following a wizard that allows for the implementation of two methodologies, i.e., component separation or pre-selection. The project was born from a collaboration between the Department of Environmental Engineering of the University of Calabria and the Department of Environmental Policies of the Calabria Region. The software was used to estimate NBLs in selected chemical species at potentially contaminated industrial sites located in Lamezia Terme, Italy. In the future, the developed calculation program will be the official evaluation tool of the Calabria Region for identifying groundwater thresholds.

Deriving Natural Background Levels of Arsenic at the Meso-Scale Using Site-Specific Datasets: An Unorthodox Method

“…The preselection approach involves the use of indicator chemical species, such as NO3, NH4, Cl, and K [15,28,29], to identify samples with most likely anthropogenic influences [14,19,[30][31][32][33][34]. The component separation approach involves the subdivision of the working dataset into normally and log-normally distributed populations, considering the latter as representative of the natural background [8,20,[35][36][37]. The new approaches mentioned above involve the combination of the preselection or component separation methods with geostatistical tools that take into account the actual distribution of the contaminant of concern and its correlation with other environmental parameters (e.g., indicator kriging [21,23,[38][39][40] or object-oriented statistics [24]).…”

Determining the Relevant Scale to Analyze the Quality of Regional Groundwater Resources While Combining Groundwater Bodies, Physicochemical and Biological Databases in Southeastern France

“…Various scales have been recommended to tackle this problem, including a groundwater catchment station, identifying sensitive points (sentinel or monitoring wells), a watershed or groundwater body area, usually presenting low geological complexity, or even a region. The approach also varies, including geochemical and multivariate statistical analysis, end-member mixing, diverse geostatistical procedures for analyzing geochemical structures, and modeling at various scales [6][7][8][9][10][11][12][13][14][15][16].…”

“…The enlargement of the areas studied by upscaling then becomes problematic because, for regional scales, the lithology can become heterogeneous, which makes the use of natural markers or tracers problematic. Thus, the management of the heterogeneity of geological characteristics during local to regional upscaling is of scientific interest in resource management [15]. For groundwater bodies, one of the keys to successfully shifting from the local to the regional scale could involve the automatic determination of units exhibiting a certain homogeneity of water-rock interaction processes or more generally of the processes involved in water diversity.…”

Natural Background Levels in Groundwater

“…The main goal of this Special Issue of Water is to bring together and discuss different methodological approaches and tools to improve the assessment of groundwater NBLs. From its first announcement, and after being thoroughly peer reviewed, nine papers have been accepted for publication [3][4][5][6][7][8][9][10][11]. To provide an overview of the experiences collected by this Special Issue, a brief summary of each published paper is reported below.…”

“…To provide an overview of the experiences collected by this Special Issue, a brief summary of each published paper is reported below. A variety of spatial scales is encountered, ranging between national [3,11], regional [3,7,8,10], meso- [6,9] and site-specific [4,5] scales, and different methodologies are applied.…”