Areal and Vertical Distribution of Nitrate Concentration in Piedmont Plain Aquifers (North-Western Italy)

2017

Environ Sci Pollut Res

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Diffuse nitrate pollution in groundwater is currently considered one of the major causes of water quality degradation. Determining the sources of nitrate contamination is an important first step for a better management of water quality. Thus, the isotopic composition of nitrate (δN and δO) and boron (δB) were used to evaluate nitrate contamination sources and to identify geochemical processes occurring in the shallow and deep aquifers of the Turin-Cuneo plain (NW Italy). The study area is essentially an agricultural zone, where use of synthetic nitrogenous fertilizers and organic manure is a common practice and the connection to sewer services is locally lacking. Also livestock farming are highly developed. A groundwater sampling campaign was performed on 34 wells in the shallow aquifer and 8 wells in the deep aquifers, to analyze nitrate, chloride, boron, δN, δO and δB. Isotope data of nitrate indicate that nitrate contamination in the Turin-Cuneo plain originates from mixtures of synthetic and organic sources, slightly affected by denitrification, and manure or septic tank effluents. Moreover, boron isotopes were used to discriminate further among the main anthropogenic sources of pollution. The analyses results confirm that both animal manure and domestic sewage, especially under the city of Turin, can contribute to the nitrate contamination. The isotope analysis was also used for the evaluation of denitrification and nitrification processes: contrary to expectations, a significant denitrification phenomenon was assessed only in the shallow unconfined aquifer, especially in the Poirino Plateau, the most contaminated sector of the study area.

“…These results are consistent with previous studies (Lasagna et al 2005;Debernardi et al 2008;Lasagna et al 2013;Lasagna et al 2015;Lasagna et al 2016b).…”

Section: % Of Monitored Points Have Nitrate Concentration Between Lsupporting

confidence: 94%

Evaluation of sources and fate of nitrates in the western Po plain groundwater (Italy) using nitrogen and boron isotopes

2017

Environ Sci Pollut Res

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“…Indeed, close to the mountain front, the lower thickness and frequency of low permeability sediments levels in the Multi-layered Villafranchian complex creates conditions for deep aquifer recharging. Owing to their features, deep aquifers are generally more protected from groundwater pollution than shallow aquifers (Lasagna et al 2015(Lasagna et al , 2016a(Lasagna et al , 2016b.…”

Section: Hydrogeological Conceptual Modelmentioning

confidence: 99%

Potential recharge areas of deep aquifers: an application to the Vercelli–Biella Plain (NW Italy)

Gisolo

et al. 2019

Rend. Fis. Acc. Lincei

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Deep aquifers typically serve as a key source of drinking water due to their good groundwater quality. Then the identification of deep aquifers recharge areas provides the local administration with a management tool to protect groundwater, through the implementation of legislative measures for the control of pollution sources. However, the location and size of recharge areas of deep aquifers are often difficult to define and generally require a large amount of data. The aim of this paper is to propose a method to identify potential recharge, throughflow and discharge areas of deep aquifers on a regional scale, due to their hydrodynamic features. As the proposed method identifies where deep aquifer recharge can occur, but not the recharge rate, delimited areas are defined as "potential". Particularly, the method analyses piezometric level differences between shallow and deep aquifers to understand groundwater flow direction.The areas where groundwater flow is downward are delimited as potential recharge areas of deep aquifers (PRADAs).The method represents a qualitative approach to the identification of PRADAs, because it permits to narrow down large plain areas extension, highlighting where potentially recharge areas are located. Then PRADAs location and shape can be defined effectively, expanding datasets and furthering analyses (hydrogeological reconstruction, hydraulic connectivity, hydro-chemical and isotopic methods…) in the identified areas.The hydrogeological setting investigated by this method is representative of many anthropized and groundwater demanding plain around the world that require to be protected. Thus, the method represents a suitable approach for 2PRADAs identification in such settings, especially in low income countries, where resource availability for studies and analyses is scarce. This method was then applied to a plain area of Northwest Italy, and the locations and sizes of potential recharge, throughflow and discharge areas of deep aquifers were identified on a regional scale.

“…Regional scale studies allow for the analysis of nitrate concentrations versus well/piezometer depths. Numerous regional scale investigations have been conducted (Piskin 1973;Spruill 1983;Detroy 1986;Hudak 1999Hudak , 2000Debernardi et al 2008;Lasagna et al 2015). These studies have observed an inverse relationship between the groundwater nitrate concentration and well depth.…”

Section: Previous Studies About Multilevel Sampling Techniques For Nimentioning

confidence: 99%

“…Nitrate has been recognised as the most widespread shallow groundwater contaminant in the Piedmont plains (NW Italy) (Lasagna 2006;Lasagna et al 2015Lasagna et al , 2016. A study based on isotopic techniques, particularly nitrogen and oxygen isotopes, determined that the nitrate contamination in some areas of the Piedmont plain is associated with synthetic nitrogen fertilisers/manure and septic tank effluents (Debernardi et al 2008).…”

Section: Introductionmentioning

confidence: 99%

The use of multilevel sampling techniques for determining shallow aquifer nitrate profiles

2016

Environ Sci Pollut Res

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Nitrate is a worldwide pollutant in aquifers. Shallow aquifer nitrate concentrations generally display vertical stratification, with a maximum concentration immediately below the water level. The concentration then gradually decreases with depth. Different techniques can be used to highlight this stratification. The paper aims at comparing the advantages and limitations of three open hole multilevel sampling techniques (packer system, dialysis membrane samplers and bailer), chosen on the base of a literary review, to highlight a nitrate vertical stratification under the assumption of (sub)horizontal flow in the aquifer. The sampling systems were employed at three different times of the year in a shallow aquifer piezometer in northern Italy. The optimal purge time, equilibration time and water volume losses during the time in the piezometer were evaluated. Multilevel techniques highlighted a similar vertical nitrate stratification, present throughout the year. Indeed, nitrate concentrations generally decreased with depth downwards, but with significantly different levels in the sampling campaigns. Moreover, the sampling techniques produced different degrees of accuracy. More specifically, the dialysis membrane samplers provided the most accurate hydrochemical profile of the shallow aquifer and they appear to be necessary when the objective is to detect the discontinuities in the nitrate profile. Bailer and packer system showed the same nitrate profile with little differences of concentration. However, the bailer resulted much more easier to use.