Water Pollution - Nitrate-Nitrite Concentration

Nitrate (NO₃-) and Nitrite (NO₂-) Concentration estimates nutrient pollution levels in freshwater. Elevated levels can lead to eutrophication and cause harmful algal blooms and ecological imbalances.

Overview

Data Type	Combination of monitoring data and a machine learning modelling
Source	Damania et al. (2019)
Spatial Resolution	Spatially explicit to river basins (HydroBASINS level 6)
Temporal Resolution	Based on predicted values for the years between 2006 and 2010, i.e. the last 5 years of available data. Official updates to be confirmed.
Interpretation	The Nitrate-Nitrite concentration value are expressed in milligrams per liter (mg/l) , The raw values are categorized into a 0-10 score based on thresholds established by scientific literature.
Concern Level	Very Low = Score 0 - 2 Low = Score 2 - 4 Moderate = Score 4 - 6 High = Score 6 - 8 Very High = 8 - 10
Framework Relevance	Nitrate-Nitrite Concentration is relevant under CSRD (ESRS E2 and ESRS E3) as well as under TNFD and SBTN.

Detailed Specifications

Explanation

Elevated Nitrate (NO₃-) and Nitrite (NO₂-) concentrations in fresh water indicate potential pollution, often stemming from agricultural runoff, excessive fertilizer use, or other anthropogenic sources. Monitoring these nitrogen compounds serves as an indicator of nutrient pollution of fresh water, which can lead to harmful algal blooms, oxygen depletion, and adverse effects on aquatic ecosystems and human health. This indicator estimates the concentration of Nitrate (NO₃-) and Nitrite (NO₂-) in surface water based on a combination of monitoring data and a machine learning prediction model.

Transformation & Interpretation

The units of the raw Nitrate-Nitrite concentration value are milligrams per liter (mg/l). The following thresholds are used to convert raw values into scores and concern levels:

Raw Values (mg/l)	Score	Concern Level
≤ 0.4	0 - 2	Very Low
0.4 - 0.8	2 - 4	Low
0.8 - 1.2	4 - 6	Moderate
1.2 - 1.6	6 - 8	High
> 1.6	8 - 10	Very High

Source

The Nitrate-Nitrite Concentration indicator provided as part of SBTN’s Water Pollution layer is sourced from Camargo et al. (2023). The underlying data stems from Damania et al. (2019).

Date of publication

2023 (2019)

Confidence & Accuracy

Medium (best available at global scale). The Nitrate-Nitrite Concentration indicator is based on a global hydrological model including past data and machine learning. The indicator might thus fail to accurately estimate current Nitrate-Nitrite concentration levels at the local scale. Nevertheless, the indicator is science-based, peer-reviewed and explicitly required for science-based target setting under SBTN.

Relevance for CSRD

CSRD requires companies to identify operational sites situated in areas of water risk, incl. areas of high-water stress. The Nitrate-Nitrite Concentration indicator is relevant under:

ESRS Article	Disclosure or application requirement
ESRS E2 AR 23 (c)	percentage of emissions of pollutants to water and soil occurring in areas at water risk, including areas of high-water stress
ESRS E3 DR 12 (c)	commitment to reduce material water consumption in areas at water risk
ESRS E3 DR 19	actions and resources in relation to areas at water risk, including areas of high-water stress
ESRS E3 DR 23 (a)	impacts, risks and opportunities related to areas at water risk, including improvement of the water quality
ESRS E3 DR 23 (c)	reduction targets for water consumption, in areas at water risk, including areas of high water-stress
ESRS E3 DR 28 (b)	total water consumption in m3 in areas at water risk, including areas of high-water stress
ESRS E3 AR 13 (b)	risks including water quantity (water scarcity, water stress), water quality (...)

CSRD requires companies to consider and describe the data used in their analysis (ESRS E4 AR 27). For convenience, here a description of for the relevant criteria:

ESRS Data Criteria	Comment
(a) methodology, reason for selection, assumptions, limitations & uncertainties	Methodology: Nitrate-Nitrite Concentration is estimated based on a global hydrological model including historic data and machine learning. Reason for selection: The indicator has been selected to assess the level of water pollution. The selected metric is science-based, peer-reviewed, widely used and specifically endorsed by SBTN guidelines. Assumptions: The indicator is model based and incorporates several assumptions detailed in Damania et al. (2019). Limitations & uncertainties: The Nitrate-Nitrite Concentration indicator is based on a global hydrological model including past data and machine learning. The indicator might thus fail to accurately estimate current Nitrate-Nitrite concentration levels at the local scale.
(b) scope of metric	The Nitrate-Nitrite Concentration indicator is applied at site level.
(c) biodiversity component of metric	The Nitrate-Nitrite Concentration is an ecosystem-level nature indicator. It assesses ecosystem structure by providing an indicator for the chemical state of the ecosystem.
(d) covered geographies	The Nitrate-Nitrite Concentration indicator has global coverage.
(e) integration of ecological thresholds	The Nitrate-Nitrite Concentration indicator relates to the planetary boundaries of freshwater change and biochemical flows.
(f) frequency of monitoring, baseline condition and period	The Nitrate-Nitrite Concentration indicator is based on a global hydrological model including data for the years between 2006 and 2010. Official updates of the indicator remain to be confirmed.
(g) data type (primary, secondary, modelled, expert judgement	The Nitrate-Nitrite Concentration indicator relies on modelled data.

Relevance for TNFD

The Nitrate-Nitrite Concentration indicator is a suitable indicator to estimate water availability under the criteria of Physical Water Risk within TNFD’s LOCATE step.

Relevance for SBTN:

The Nitrate-Nitrite Concentration indicator represents one out of three water pollution indicators explicitly required to use as a pressure-sensitive State of Nature indicator in SBTN Step1: Assess and Step 2: Interpret & Prioritize.

SBTN Data & Tool Criteria	Evaluation	Comment
Relevance	✅	NNC contributes to the pressure-sensitive state of nature metric water pollution required by SBTN methodology.
Representative	✅	NNC data represents a close fit with the SBTN characterization of the water pollution issue and is appropriate to be applied under Step 1 & 2.
Spatial and Temporal Resolution	✅	The NNC indicator is provided at the spatial resolution of level 6 of Hydrological sub-basin (HydroBASINS 6). The NCC indicator is based on average predicted values between 2006 and 2010, i.e. the last 5 years of available data.
Stability and Preservation	✅	NCC data sets are likely to be maintained and preserved long-term as they are provided by SBTN.
Accessibility	✅	The NCC data is readily accessible online.
Interpretability	✅	The NCC indicator is sufficiently interpretable and generates an appropriate input for the SBTN methodology.
Coverage	✅	NCC has global coverage.
Authoritative and Accurate	✅	NCC data is science-based, peer-reviewed and explicitly required by SBTN.