Magnesium as Environmental Tracer for Karst Spring Baseflow/Overflow Assessment—A Case Study of the Pertuso Karst Spring (Latium Region, Italy)

Abstract

Following a previous research carried out on the same site, this paper presents the update of the Mg2+ based method for the estimation of Pertuso Spring discharge, located in Central Italy. New collected data confirmed the validity of the proposed model and the conservative behaviour of Mg2+ for groundwater related to the Pertuso Spring aquifer. Further analysis allowed to obtain a local linear relationship between magnesium concentration and total spring discharge (including exploitation rate), regardless of the mixing model proposed with the Aniene River. As regards two samples which fall out of the linear relationship and could have been detected as “outliers”, more in-depth data processing and sensitivity analyses revealed that the lowering in magnesium, at equal discharges, is determined by the appearance of the quick-flow component, less mineralized and related to storm events. Results showed that under specific conditions, related to the absence or presence of previous intense rainfall events, Mg2+ could be effectively a useful tracer for separating spring conduit flow (overflow) from diffuse flow (baseflow) within the karst aquifer.

Responses of Spring Discharge to Different Rainfall Events for Single-Conduit Karst Aquifers in Western Hunan Province, China

“…Many methods are applied to identify karst groundwater systems, such as hydrogeochemical analysis [ 10 ], environmental isotope method [ 11 , 12 , 13 ], time-series analysis [ 14 , 15 ] and artificial tracer tests [ 16 , 17 ]. Tracer tests provide the most effective means for identifying the point-to-point connections between flow inputs (sinkholes or sinking streams) and outputs (springs).Tracer test can not only identify the flow path of karst groundwater, but also can calculate the geometric parameters (transport velocities and dispersion) of groundwater flow, which is helpful to analyze the internal structure of karst aquifers [ 18 ].…”

Study of dilution processes of sulfidic aquifer hosted by the Fiume-Vento karstic complex, Frasassi (Central Italy)

“…Chloride and sodium are the most used among the natural conservative tracers for hydrogeological investigations (e.g., Tazioli and Palpacelli 2013). Some other study suggests using magnesium in areas with abundant dolomite (Sappa et al 2017;De Filippi et al 2021).…”

Numerical simulation and protection of the dynamic change of Jinan karst spring based on coupling of seepage and conduit flow

“…Natural tracers are effectively used for spring hydrograph separation, discharge assessment, and to distinguish between matrix and conduit flow. For example, Mg 2þ could be an effective tracer for separating spring conduit flow from diffuse flow within a karst aquifer (De Filippi et al, 2021). Additionally, water electrical conductivity and temperature act as natural environmental tracers, which can provide valuable insight into the characteristics of groundwater flow systems and intrinsic processes (Stroj et al, 2020).…”