International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers - CN225

Contribution ID: 258 Type: Poster

HYDROGEOLOGICAL AND HYDROGEOCHEMICAL STUDY OF THE ARCHAEOLOGICAL SITE (PHLEGRAEAN FIELDS, SOUTHERN )

The Cumae archaeological site is located along the Tyrrhenian coast of the southern Italy, in the coastalarea north-west of the Flegrean Fields active volcanic system. It is the first Greek colony in mainland Italy, was founded in the 8th century B.C., and the site remained continuously occupied until the 12th century A.D.. The coastal plain of the Cumae archaeological site is an area of relevant environmental and archaeological interest. During the Holocene epoch it has changed significantly, due to endogenous and exogenous phenom- ena, such as volcanic eruption and eustatic sea-level variations, associated to the creation of lake environments and palustrine wetlands. As a result of these natural processes, the coastal plain is characterized by a complex volcanic-sedimentary sequence formed by sands, silts, silty clays and volcanoclastic sediments, resting on a substrate of yellow and trachytic laves, outcropping in the surrounding reliefs. The geomorphological features are typical of a coastal plain, with altitude range of 0-15 meters a.s.l., consti- tuted, from the sea toward the inland, by beach-dune systems followed by a low inclination zone back-dune and slope areas belonging to volcanic reliefs. The climate is Mediterranean type, with hot dry summers and moderately cool and rainy winters. Meanannual air temperatures are in the range of approximately 13–15 ℃. Rainfall regime is of a coastal and Mediterranean type, characterised by a principal maximum in autumn-winter and a minimum in the summer. The average annual rainfall is about 700 mm/y. Land use of this coastal area has been traditionally dedicated to intensive irrigated agriculture, with use of pesticide and organic fertilizers. Within the coastal plain, in an experimental site, having an extension of approximately 0.5 km2, a well- designed hydrological, hydrogeological, chemical and isotopic monitoring program has been carried out, dur- ing the period November 2013-November 2014. Based on a detailed stratigraphic model of the study area, multidisciplinary investigations (hydrological mon- itoring, piezometric measurements, sampling and laboratory water analysis) were conducted, on a monthly basis, on a total of 13 wells and 1 spring, to analyse: i) groundwater quality, ii) natural and anthropogenic processes that affect the hydrochemical and isotopic composition of groundwater in the coastal volcanic- sedimentary aquifer, and iii) the complex interactions exiting between groundwater and subterranean archae- ological structures and artifacts. Groundwater samples were analysed to identify various physico-chemical and isotopic parameters: temper- ature, pH, electrical conductivity, total dissolved solids, major ions and trace elements, 18O, , 222Rn, and some heavy metals. Hydrostratigraphic data and piezometric monitoring confirm the presence of a multi-layered system ina coastal volcanic-sedimentary aquifer, whereas all the hydrochemical and isotopic observations show that the groundwater quality is affected by: i) aquifer lithologies and localised rise of deep magmatic fluids highly mineralized, ii) freshwater-saltwater interactions (induced by groundwater pumping), and iii) contamination from non-point agricultural sources.

Primary author: Dr ALLOCCA, Vincenzo (University of Federico II) Co-authors: Prof. FERRARA, Luciano (University of Naples Federico II); Dr STELLATO, Luisa (Second Univer- sity of Naples); Prof. ARIENZO, Michele (University of Naples Federico II); Prof. DE VITA, Pantaleone (University of Naples Federico II) Presenters: Dr STELLATO, Luisa (Second University of Naples); Dr ALLOCCA, Vincenzo (University of Naples Federico II)

Track Classification: Groundwater Resources, Age Dating, and Geochemical Evolution