Nitrogen-neutrality: a step towards sustainability

Abstract

We propose a novel indicator measuring one dimension of the sustainability of an entity in modern societies: Nitrogen-neutrality. N-neutrality strives to offset Nr releases an entity exerts on the environment from the release of reactive nitrogen (Nr) to the environment by reducing it and by offsetting the Nr releases elsewhere. N-neutrality also aims to increase awareness about the consequences of unintentional releases of nitrogen to the environment. N-neutrality is composed of two quantified elements: Nr released by an entity (e.g. on the basis of the N footprint) and Nr reduction from management and offset projects (N offset). It includes management strategies to reduce nitrogen losses before they occur (e.g., through energy conservation). Each of those elements faces specific challenges with regard to data availability and conceptual development. Impacts of Nr releases to the environment are manifold, and the impact profile of one unit of Nr release depends strongly on the compound released and the local susceptibility to Nr. As such, Nneutrality is more difficult to conceptualize and calculate than C-neutrality. We developed a workable conceptual framework for N-neutrality which was adapted for the 6th International Nitrogen Conference (N2013, Kampala, November 2013). Total N footprint of the surveyed meals at N2013 was 66 kg N. A total of US$ 3050 was collected from the participants and used to offset the conference's N footprint by supporting the UN Millennium Village cluster Ruhiira in South-Western Uganda. The concept needs further development in particular to better incorporate the spatio-temporal variability of impacts and to standardize the methods to quantify the required N offset to neutralize the Nr releases impact. Criteria for compensation projects need to be sharply defined to allow the development of a market for N offset certificates.

Nitrogen footprints: Regional realities and options to reduce nitrogen loss to the environment

“…N footprint tools have been developed for individuals, institutions, and even individual food products as a part of the N-Print project (http://www.N-Print.org; Leach et al 2012Leach et al , 2013Leip et al 2014a). Quantitative information provided by the N footprint may help entities understand the connection between Nr loss to the environment and the entities' daily activities.…”

“…The N footprint concept has also been applied to individual food products (e.g., N-Label; Leach et al 2016) and to events (e.g., N-Neutrality; Leip et al 2014a). …”

“…The numbers in green circles represent the points of where key actions to reduce Nr losses to the environment, listed in Table 3 in detail The N footprint tools discussed so far focus on informing the user about their contribution to Nr losses to the environment. The N-Neutrality concept proposed by Leip et al (2014a) is one option to measure, reduce, and compensate the N footprint for a specific event or activity. The N-Neutrality approach consists of two steps.…”

“…Then, to offset the remaining N footprint, the user contributes with a measured compensation in support of a project that would help mitigate or reduce Nr losses. An example is providing funding towards a sustainable agriculture project (e.g., locally implemented projects) Leip et al 2014a). …”

Quantitative evaluation of reactive nitrogen emissions with urbanization: a case study in Beijing megacity, China

“…The countermeasures of N offset could be developed to heighten Nr removal efficiency to avoid inefficient Nr removal, resulting in the overall reduction of Nr emissions. The concept of N offset is similar to the BN neutrality^concept defined by Leip et al (2014) in that the purchase of N offsets compensates for residual Nr releases after removal. In this case, N offset could be purchased by government to neutralize the excess Nr emissions in a previous inefficient year with output slack by supporting low N-producing projects, thus encompassing a reduction of Nr release elsewhere in Beijing during a specific period.…”