Did green infrastructure improve water purification ecosystem services in Shandong Peninsula urban agglomeration?...

Non-point source pollution significantly impacts the sustainable development of river ecosystems. Water purification ecosystem services (WPES) play a crucial role in mitigating non-point source pollution. Green infrastructure (GI) maintains ecosystem services; however, how GI affects WPES remains poorly explored. Using total phosphorus (TP), we investigated the mechanisms by which GI and its structure and functions influence WPES in the Shandong Peninsula urban agglomeration. Results show that GI significantly improved WPES, with the lower TP loads (49-fold) and TP export capacity (3-fold) in GI areas compared to non-GI areas. These effects are associated with specific GI attributes, including structural connectivity, vegetation coverage, and soil conservation capability, which exhibit cascading effects (|r| > 0.8). Optimizing GI structural connectivity can indirectly regulate WPES by enhancing GI ecological functions (vegetation coverage and soil conservation), making it a crucial land management strategy. Specifically, the enhancement of vegetation coverage, which is critical for improving WPES (|r| > 0.6), should focus on both the 'scale' and 'health' of the vegetation. Cultivating GI (|r| > 0.6) offers greater benefits for WPES than forests and grasslands alone (|r| < 0.6). Effectively leveraging the relationships between GI attributes and WPES can significantly reduce TP risks.