Spatiotemporal coupling between rice production, urea use and coastal nitrate dynamics in the marine ecosystem of Lambayeque, Perú
Description
This study evaluated the spatiotemporal association between rice-related agricultural pressure and nitrate content in the marine-coastal ecosystem of Lambayeque, Peru, during 2022–2025. Annual rice-production and urea-import indicators were integrated with monthly Copernicus Marine Service series for nitrate (NO₃⁻), alkalinity, biomass, carbon, chlorophyll a, carbon dioxide (CO₂), phytoplankton and dissolved oxygen (O₂). The northern zone was represented by Drain 1000, while the southern zone integrated drains 1600, 1700 and 4000. Rice production showed a positive association with urea imports (r = 0.90; R² = 81.42 %) and with marine nitrate in the northern (R² = 81.19 %) and southern (R² = 81.68 %) zones. Nitrate increased mainly from May to October, with more persistent concentrations in the southern zone. Monthly correlations showed positive coupling between nitrate, carbon and carbon dioxide, together with significant negative associations with dissolved oxygen. These results indicate that rice-related agricultural pressure is associated with a measurable marine nitrate signal accompanied by changes in the carbonate system, biological productivity and oxygenation. The integrated approach supports sector-based monitoring during critical periods along the Lambayeque coast.