[This dataset is embargoed until December 15, 2026]. Sites were monitored for key water quality indicators, including: water quality parameters (temperature, pH, electrical conductivity, salinity, dissolved oxygen and turbidity), water samples collected for subsequent nutrient analysis (for dissolved inorganic nitrogen and phosphate), and where possible seagrass or algal samples were collected for isotopic composition. Water quality data was collected across a range of sites in Laamu atoll between 2022 and 2024 to develop a baseline understanding of water quality, to help characterise nutrient loading and identify potential sources of nutrient pollution. The sampling was conducted on varying spatial and temporal scales. This included a variety of island types (e.g., inhabited, uninhabited, agricultural, tourism islands, pristine patch reefs), and within individual islands. Sampling was conducted across a spectrum of uses-types of different sites (e.g., densely populated areas, versus heavy agricultural areas, vs rural areas etc) between different seasons (wet and dry seasons) on monthly, quarterly, bi-annual and annual time-windows. Repeat sampling was conducted on several sites several times a year and over 2 years to get a sense of change over time and within season.

The database includes the classification of 966 active nitrogen-relevant policies from South Asia (including Afghanistan, Pakistan, India, Nepal, Bhutan, Bangladesh, the Maldives and Sri Lanka). The collection during 2020 and 2021 focuses on national level policies; some subnational policies were also collected. Data collection involved building on an existing open access global database developed by Kanter et al., 2020 that contained 51 policies for South Asia established to 2017 sourced by the environmental law ECOLEX database. Further policies were collected mostly from online sources: such as international policy databases: FAOLEX and national government and ministry websites. A protocol for policy collection and classification was established and followed to ensure consistent and thorough collections across the eight countries. Policies were classified according to a variety of parameters including the sink (air, water etc.) and sector (agriculture, industry etc.) they address and by type of policy. Policies were clustered if they had a central node policy in place and if a ‘subordinate policy’ (including amendments) did not offer anything new in terms of content related to Nitrogen management. This data was collected as part of a collective partnership that brings together leading organisations from across South Asia and the UK to reduce the adverse global impacts of nitrogen pollution on the environment, health, and wellbeing. More specifically providing a resource for both SANH partners and the wider scientific and policy community to understand the nitrogen policy landscape in the south Asian region. Furthermore, this research contributes to efforts in building a nitrogen policy arena promoting sustainable management of nitrogen, mitigating adverse effects. The dataset provides a thorough overview of available nitrogen related policies in South Asia but does not provide a complete set of all the nitrogen relevant policies available in each country. In some cases, this was due to our dependency on policy availability online, and some websites were not maintained. In addition, we excluded policies established post 2020 to avoid policy responses to COVID19 and to align more closely with the original global study. Repealed policies were omitted from the database. Full details about this dataset can be found at https://doi.org/10.5285/e2f248d5-79a1-4af9-bdd4-f739fb12ce9a