Humans have massively altered flows of nitrogen on our planet, leading to both benefits for food production and multiple threats to the environment. There are few places on Earth more affected than South Asia, with levels of nitrogen pollution rapidly increasing. The result is a web of interlinked problems, as nitrogen losses from agriculture and from fossil fuel combustion cause air and water pollution. This damages human health, threatens biodiversity of forests and rivers, and leads to coastal and marine pollution that exacerbates the effects of climate change, such as by predisposing reefs to coral bleaching. Altogether, it is clear that nitrogen pollution is something we should be taking very seriously.

This challenge is taken up by a major new research hub established under the UK Global Challenge Research Fund. The “GCRF South Asian Nitrogen Hub” is a partnership that brings together 32 leading research organisations with project engagement partners from the UK and South Asia. All eight countries of the South Asia Co-operative Environment Programme (SACEP) are included.

The hub includes research on how to improve nitrogen management in agriculture, saving money on fertilizers and making better use of manure, urine and natural nitrogen fixation processes. It highlights options for more profitable and cleaner farming for India, Pakistan, Bangladesh, Nepal, Afghanistan, Sri Lanka, Bhutan and the Maldives. At the same time, the hub considers how nitrogen pollution could be turned back to fertilizer, for example by capturing nitrogen oxide gas from factories and converting it into nitrate.
There are three scales with mutual feedback:

A) INMS will be a key receiving body for the hub research results, enabling the results to be embedded into the first International Nitrogen Assessment (2022), into INMS guidance documentation and into support for policy.

B) The SACEP / INMS / UN Environment link will enable the hub to reach global partners, including the Task Force on Reactive Nitrogen of the UNECE Geneva Air Convention, the UNEP-led GPA on land-marine environmental protection, the Convention on Biological Diversity, the UNFCCC (e.g. Koronivia Joint Work), the Vienna Convention on Stratospheric Ozone (relevant for N2O), OECD and UN Agenda 2030 on the Sustainable Development Goals.

C) The consensus building through SACEP will allow South Asia to champion hub outcomes to UNEA and globally (e.g., World Environment Day, New Delhi 2018; proposed 2020 Nitrogen Summit, Berlin; concept for the Inter-convention Nitrogen Coordination Mechanism – ‘UN Nitrogen’).

Different Work Packages under RP4

WP4.1 team identifies common and special data needs across all WPs under RP4, taking account of data quality and uncertainty, data access and sharing requirements. This is carried out collaboratively across all partners involved in WP4.1 and with input from the modelling communities under RP4 (air, soil and water quality & health, greenhouse gases and climate resilience).

This WP delivers harmonized datasets (including human population, livestock, crops, fertilizer, land cover, soils etc.); High resolution atmospheric emission maps; Scenario modelling output; South Asia-wide and national nitrogen budgets (combining RP4)

WP 4.2applies an ensemble of leading atmospheric models for SA to assess the contribution of reactive N emissions to particulate matter (PM), NO2 and NH₃ concentrations and their human health impacts. Model assessment against existing monitoring networks and new measurements will allow model application for abatement scenarios.

A 10-site network for Nr measurement operated for 24 months from the IGP to the Himalayan foothills will deliver validation data and help elucidate the underlying chemical transformations. Inversions of satellite-derived NH3 and NOx data using WRFChem will be conducted to constrain the estimated emissions. The WP will deliver better understanding of urban-rural sources of Nr, pollution maps and a validated basis to consider future N scenarios.

WP4.3 aims to understand the complex system of nutrient sources and demands, and to quantify the impact of various (agric., waste, landscape, consumption) scenarios on lives and livelihoods in SA. A process-based simulation model of the region linking air, land, freshwater and marine nutrient flows and impacts based on LTLS-NEMO-ERSEM will be developed and the system will be validated with satellite and in-situ observations. The model output will be used to explore impacts of urban and rural land use and climate change, following stakeholder scenario consultation. Building on partner modelling capabilities (e.g. MIKE-SHE, QUAL2Kw, WRF, FV-COM), we will nest high-resolution case study models of catchment water quality, coastal embayment, island chains (e.g. Maldives, Andaman) and coral reefs to underpin the WP3.2 investigation of the role of eutrophication in exacerbating coral bleaching & coastal impacts.

Assessment of health risks will combine analysis of clinical data, qualitative interviews with local communities and review of whether WHO guideline values are adequate (e.g. as N-nitrosamines combines with additional carcinogenic risks). Supporting data collation will consider costs of care and early detection, recognition & chronic management of N-linked disease.

Work Package 4.4 focuses on regional modelling of soil N₂O emissions, and other greenhouse gases (GHG). The primary focus is to upscale N₂O emissions using the IPCC Tier 1,2 and 3 methods (IPCC 2006). The most robust models will be used to provide regionally disaggregated emission inventories of the SA countries, and constrained by available observations from aircraft, towers and satellite data and assess the impact of the policy scenarios developed in WP 1.2 on N₂O and other GHG emissions.

The first task for WP 4.4 is to identify the available data (GHG data and activity data) required. A few process based models will be used to extrapolate to some regions within GIS platforms, using harmonized data developed within RP4, where possible.