NITRATES IN GROUNDWATER

    Descrizione 1
    Update date
    Authors

    Giordano Giorgi, Marilena Insolvibile, Massimo Peleggi, Silvana Salvati

    Abstract
    Immagine
    Abstract

    The indicator provides the percentage of groundwater monitoring stations divided into quality classes based on the average nitrate concentration recorded over a four-year monitoring period (2016–2019). Specifically:

    • 68.1% of stations show an average nitrate concentration below 25 mg/L,
    • Only 12.6% of monitored points recorded an average concentration equal to or above 50 mg/L.

    Additionally, an analysis comparing the trend over the last four years (2016–2019) to the previous four years (2012–2015) reveals predominantly stable nitrate concentrations, a decrease in average concentration at 37.9% of common stations between the two periods, and an increase at only 22.7% of the same stations.

    Description

    Nitrate monitoring in groundwater is conducted under the Nitrates Directive (Directive 91/676/EEC), which aims to protect waters from pollution caused or induced by agricultural nitrates. For groundwater, the threshold value for nitrate concentration is 50 mg/L.

    The quality classes are as follows (from worst to best):

    • ≥ 50 mg/L - Red
    • Between 40 and 49.99 mg/L - Orange
    • Between 25 and 39.99 mg/L - Yellow
    • Between 0 and 24.99 mg/L - Green

    The quality classes for trends are as follows (from worst to best):

    • Strong increase: > 5 mg/L - Red
    • Mild increase: +1 to 5 mg/L - Orange
    • Stable: -1 to +1 mg/L - Yellow
    • Mild decrease: -5 to -1 mg/L - Green
    • Strong decrease: < -5 mg/L - Blue

    For each concentration and trend quality class, the percentage of groundwater monitoring sites falling into that class is provided.

    Monitoring aims to identify polluted or at-risk waters, designate vulnerable zones (areas where nitrate pressures make them particularly sensitive and prone to pollution if not addressed), define Action Programs (a series of measures to prevent and reduce nitrate pollution), and, ultimately, develop Codes of Good Agricultural Practice that establish a set of good practices.

    Purpose

    To evaluate, over the medium to long term, the impact of human activities related to nitrate inputs into groundwater. These activities include the use of fertilizers for agricultural crops, the presence of livestock—particularly intensive farming—and untreated wastewater that percolates into groundwater.

    Policy relevance and utility for users
    It is of national scope or it is applicable to environmental issues at the regional level but of national relevance.
    It can describe the trend without necessarily evaluating it.
    It is simple and easy to interpret.
    It is sensitive to changes occurring in the environment and/or in human activities
    It provides a representative picture of environmental conditions, environmental pressures, and societal responses
    It provides a basis for international comparisons.
    Ha una soglia o un valore di riferimento con cui può essere confrontato
    Analytical soundness
    Be based on international standards and international consensus about its validity;
    Be theoretically well founded in technical and scientific terms
    Presents reliability and validity of measurement and data collection methods
    Temporal comparability
    Spatial comparability
    Measurability (data)
    Adequately documented and of known quality
    Updated at regular intervals in accordance with reliable procedures
    Readily available or made available at a reasonable cost/benefit ratio
    An “adequate” spatial coverage
    An “appropriate” temporal coverage
    Main regulatory references and objectives
    • Nitrates Directive 91/676/EEC – Article 10
    • Directive 2000/60/EC
    • Legislative Decree No. 152/2006
    • Legislative Decree No. 30/2009
    • Ministerial Decree of July 6, 2016

    Reference threshold for nitrate concentration in groundwater: 50 mg/L

    DPSIR
    State
    Indicator type
    Descriptive (A)
    References

    Relazione ex articolo 10 della Direttiva 91/676/CEE ITALIA - Quadriennio 2016-2019 Sito web Commissione europea su Direttiva nitrati: https://environment.ec.europa.eu/topics/water/nitrates_en Report from the commission to the council and the European Parlament on the implementation of Council Directive 91/676/EEC concerning the protection of waters against pollution caused by nitrates from agricultural sources based on Member State reports for the period 2016–2019 – https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=COM%3A2021%3A1000%3AFIN&qid=1633953687154

    Frequenza di rilevazione dei dati
    Annuale
    Fonte dei dati
    SINTAI
    Data availabilty

    SINTAI - https://www.sintai.isprambiente.it - Sezione Direttiva 91/676 > Accesso dati reporting Nitrati

    Spatial coverage

    National, Regional

    Time coverage

    2008-2019

    Processing methodology

    The percentage of groundwater monitoring sites is calculated relative to the total number of sites falling within quality classes, which are identified by nitrate concentration intervals and the variation intervals of nitrate concentrations between the average values of the current four-year period (2016–2019) and the previous four-year period (2012–2015).

    Update frequency
    Four-year
    Qualità dell'informazione

    The quality of the information provided is very good, given the robustness of nitrate analysis methods and the selection of monitoring sites based on a thorough understanding of the territory and the pressures acting upon it (agriculture, livestock farming, untreated wastewater discharges).

    State
    Medium
    Trend
    Steady
    State assessment/description

    Regarding groundwater, the results of the distribution of monitoring stations across different quality classes (0–24.99 mg/L, 25–39.99 mg/L, 40–49.99 mg/L, and ≥50 mg/L) show that out of 4,612 sampling points for the 2016–2019 period:

    • 68.1% of the stations had an average nitrate concentration below 25 mg/L,
    • Only 12.6% of the monitored points recorded an average concentration equal to or above 50 mg/L (Table 2, Figure 1).
    Trend assessment/description

    From the analysis of trends between the previous four-year period (2012–2015) and the current period (2016–2019), it was found that the average nitrate concentration decreased in 37.9% of the 3,431 common stations between the two periods, while an increase was recorded in only 22.7% of the same stations. A stable trend prevails, observed in 39.4% of the stations (Table 3, Figure 2).

    Comments

    Within the regional nitrate network, ARPA/APPA conducts nitrate concentration monitoring at groundwater and surface water sampling stations affected by agricultural pressures and forwards the data to ISPRA. Every four years, ISPRA submits a report to the European Commission on the implementation status of the Nitrates Directive (Directive 91/676/EEC) across the national territory.

    For the 2016–2019 period, the number of stations ranged from a maximum of 581 in Umbria to a minimum of 30 in the province of Trento, totaling 4,612 stations (Table 2). Emilia-Romagna had the highest number of stations with an average concentration of <25 mg/L NO3 (368), while Umbria recorded the highest number of stations with an average concentration of ≥50 mg/L NO3 (Table 1, Figure 1). All stations in the ≥50 mg/L NO3 class are subject to requirements defined by the Nitrates Directive.

    Based on nitrate concentrations due to agricultural pressures, Nitrate Vulnerable Zones (ZVN) are designated as particularly sensitive areas at risk of pollution without intervention. Control programs and actions to prevent and reduce nitrate pollution are then identified (Figure 1).

    Over the last two four-year periods, the Nitrates Directive monitoring network underwent revision due to various factors such as changes in the significance of agricultural pressures and sampling feasibility. As a result, the number of stations decreased from 5,035 in 2012–2015 to 4,612 in 2016–2019, with 3,431 common sampling points (Table 1).

    A significant increase in nitrate concentration (>5 mg/L) was observed in 14.6% of stations in Basilicata compared to the previous period, while a significant decrease (<-5 mg/L) was noted in 87.1% of stations in Calabria. These variations are also influenced by the number of stations identified for monitoring (48 in Basilicata and 85 in Calabria) (Table 3, Figure 2).

    In general, it can be stated that most monitored aquifers are characterized by a stationary or improving situation concerning nitrate contamination.

    Data
    Headline

    Table 1: Network monitoring nitrate groundwater

    Data source

    ISPRA elaboration on SINTAI data - Directive 91/676 four-year-olds 2012-2015, 2016-2019

    Headline

    Table 2: Distribution of monitoring stations in different quality classes

    Data source

    ISPRA processing on data SINTAI Directive 91/676 four-year period 2016-2019

    Headline

    Table 3: Trend of the average nitti concentration four-year-olds 2016-2019, 2012-2015

    Data source

    ISPRA processing on data SINTAI Directive 91/676

    Thumbnail
    Headline

    Figure 1: Average nitrate concentration quality class 2016-2019

    Data source

    ISPRA processing on data SINTAI Directive 91/676 four-year period 2016-2019

    Thumbnail
    Headline

    Figure 2: Quality Class of trends of the average nitrate concentration (2016-2019, 2012-2015)

    Data source

    ISPRA processing on data SINTAI Directive 91/676 four-year period 2016-2019

    English