De-identified monitoring dataset for chronic nitrogen enrichment across regional drinking-water sources in Qingdao (April 2023–December 2025)

This dataset accompanies the manuscript: "Chronic nitrogen enrichment and episodic pollution pulses across regional drinking-water sources: A 33-month monitoring network in Qingdao, northern China." The repository contains de-identified monitoring data and reproducibility materials used in the manuscript. Contents include: • station-month dataset• reconstructed monitoring dataset• source metadata• data dictionary• analysis scripts• source data for all figures• Supporting Information tables• reproducibility workflow• monitoring-site KML/KMZ files The monitoring archive covers April 2023–December 2025 and includes: • 16 important drinking-water sources• 33 monitoring months• 792 individual monitoring records• 528 station-month identifiers• 522 valid observations after quality screening The repository contains only de-identified analytical datasets and reproducibility materials. Original administrative monitoring records remain under the ownership of the data-holding institution and are not redistributed. The data are provided solely for scientific reproducibility.