SRL study reporting limit (concentration cutoff for applying the ≤ symbol) ssL C sample-specific critical level US United States UV ultraviolet V analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment VCDT Vienna Canon Diablo Troilite (the international reference standard for sulfur isotopes) VPDB Vienna Pee Dee Belemnite (the international reference standard for carbon isotopes) VSMOW Vienna Standard Mean Ocean Water (an isotopic water standard defined in 1968 by the International Atomic Energy Agency) Organizations

18, and historical groundwater samples for shallow zones, intermediate zones, and deep zones .