Nitrogen and sulphur cycling in the saline coastal aquifer of Ferrara, Italy. A multi-isotope approach

Caschetto, Mariachiara; Colombani, Nicolò; Mastrocicco, Micòl; Petitta, Marco; Aravena, Ramón

doi:10.1016/j.apgeochem.2016.11.014

Cited by 33 publications

(26 citation statements)

References 55 publications

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“…Eh values between +150 and −385 mV, with a prevalence of negative values around -200 mV, have been previously detected in A0 all around the investigated area [68][69][70][71][72], confirming the occurrence of reducing conditions. The occurrence of the peat-rich facies in the central sector is expected to favor much higher arsenic concentrations in groundwater with respect to the western and eastern sectors.…”

Section: Conceptual Model Of the Investigated Systemsupporting

confidence: 66%

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

Filippini

Zanotti

Bonomi

et al. 2021

Water

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Arsenic is found in groundwater above regulatory limits in many countries and its origin is often from natural sources, making the definition of Natural Background Levels (NBLs) crucial. NBL is commonly assessed based on either dedicated small-scale monitoring campaigns or large-scale national/regional groundwater monitoring networks that may not grab local-scale heterogeneities. An alternative method is represented by site-specific monitoring networks in contaminated/polluted sites under remediation. As a main drawback, groundwater quality at these sites is affected by human activities. This paper explores the potential for groundwater data from an assemblage of site-specific datasets of contaminated/polluted sites to define NBLs of arsenic (As) at the meso-scale (order of 1000 km2). Common procedures for the assessment of human influence cannot be applied to this type of dataset due to limited data homogeneity. Thus, an “unorthodox” method is applied involving the definition of a consistent working dataset followed by a statistical identification and critical analysis of the outliers. The study was conducted in a highly anthropized area (Ferrara, N Italy), where As concentrations often exceed national threshold limits in a shallow aquifer. The results show that site-specific datasets, if properly pre-treated, are an effective alternative for the derivation of NBLs when regional monitoring networks fail to catch local-scale variability.

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Section: Conceptual Model Of the Investigated Systemsupporting

confidence: 66%

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

Filippini

Zanotti

Bonomi

et al. 2021

Water

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“…The analysis of stable isotopes coupled to hydrochemical investigations is a widely accepted approach to understand biogeochemical processes in groundwater. Multi-isotopic analyses have been applied to elucidate NO 3 sources (Vitòria et al, 2004;Kendall et al, 2007) as well as to trace major biogeochemical cycles and their related bacterial-mediated redox reactions in aquifers and surface water systems (Jurado et al, 2013;Puig et al, 2013;Hosono et al, 2014;Caschetto et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

A multi-isotopic approach to investigate the influence of land use on nitrate removal in a highly saline lake-aquifer system

Valiente

Carrey

Otero³

et al. 2018

Science of The Total Environment

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Endorheic or closed drainage basins in arid and semi-arid regions are vulnerable to pollution. Nonetheless, in the freshwater-saltwater interface of endorheic saline lakes, oxidation-reduction (redox) reactions can attenuate pollutants such as nitrate (NO). This study traces the ways of nitrogen (N) removal in the Pétrola lake-aquifer system (central Spain), an endorheic basin contaminated with NO (up to 99.2mg/L in groundwater). This basin was declared vulnerable to NO pollution in 1998 due to the high anthropogenic pressures (mainly agriculture and wastewaters). Hydrochemical, multi-isotopic (δO, δN, δC, δO, and δH) and geophysical techniques (electrical resistivity tomography) were applied to identify the main redox processes at the freshwater-saltwater interface. The results showed that the geometry of this interface is influenced by land use, causing spatial variability of nitrogen biogeochemical processes over the basin. In the underlying aquifer, NO showed an average concentration of 38.5mg/L (n=73) and was mainly derived from agricultural inputs. Natural attenuation of NO was observed in dryland farming areas (up to 72%) and in irrigation areas (up to 66%). In the Pétrola Lake, mineralization and organic matter degradation in lake sediment play an important role in NO reduction. Our findings are a major step forward in understanding freshwater-saltwater interfaces as reactive zones for NO attenuation. We further emphasize the importance of including a land use perspective when studying water quality-environmental relationships in hydrogeological systems dominated by density-driven circulation.

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“…In addition, it is worth mentioning that NO 2 − , an intermediate product of nitrification and denitrification, is present at a very small concentration in groundwater compared to nitrate and ammonium [20]. In recent years, nitrogen-stable isotopes are more often employed to assess different sources of pollution and nitrogen transformation in aquifers [21][22][23][24][25][26]. Although, in the abovementioned studies, NO 3 − was found to be the dominant nitrogen species in the oxic zone while NH 4 + was the dominant nitrogen species in the anoxic zone, their coexistence has been often limited to narrow reactive fringes.…”

Section: Introductionmentioning

confidence: 99%

Reactive and Mixing Processes Governing Ammonium and Nitrate Coexistence in a Polluted Coastal Aquifer

et al. 2018

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A comprehensive hydrochemical, stable isotope and microbial analyses characterisation has been performed to evaluate the sources of groundwater, nitrogen pollution and degradation processes occurring in an industrial polluted coastal aquifer in the framework of a complex hydrodynamic system. The coexistence of ammonium and nitrate has been observed in almost all the investigated monitoring wells, reaching maximum values of 100 and 200 mg/L for both species. Chloride and potassium concentration coupled with groundwater stable isotopes data show the influence of local and urban recharge and the occurrence of seawater intrusion in areas near the coastline. δ 15 N-NH 4 + values ranging between −4.9 and +14.9% suggest that different processes such as partial nitrification of ammonium, probably anammox activities and sorption, are occurring at the site. The isotope data for NH 4 + also showed the existence of the remnant of an old fertilizer plume in the downgradient area. The nitrate isotope data ranging between +9 and +46% and +6 and +26% for δ 15 N-NO 3 − and δ 18 O-NO 3 − , respectively, suggest that nitrate content is attenuated by denitrification and probably annamox. The fast groundwater flow field is one of the reasons for the coexistence of NH 4 + and NO 3 − in groundwater, since both compounds can penetrate the reducing zone of the aquifer. The influence of leakage of sewage pipelines on the aquifer cannot be discerned due to the complexities of the nitrogen attenuation processes, also influenced by pumping activities.

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Nitrogen and sulphur cycling in the saline coastal aquifer of Ferrara, Italy. A multi-isotope approach

Cited by 33 publications

References 55 publications

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

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

A multi-isotopic approach to investigate the influence of land use on nitrate removal in a highly saline lake-aquifer system

Reactive and Mixing Processes Governing Ammonium and Nitrate Coexistence in a Polluted Coastal Aquifer

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