Work

Ecological recovery trajectories of coastal wetlands following oil-well abandonment in the Yellow River Delta

Year: 2026

Type: article

Abstract: Introduction: Oil-well retirement ends production but may leave physical, chemical and ecological legacies in coastal wetlands. Methods: We assessed soil conditions, heavy-metal risk and vegetation across retirement stages in the Yellow River Delta, China, in 2021, using 15 oilfield-associated sites and six natural reference wetlands. Sites were classified as Active, Abandoned, Restored (infrastructure removed and restoration implemented) or Reference, with retired sites assigned to <3, 3-5 and 5-10 year classes. Results: Oilfield sites had lower mean vegetation cover than reference wetlands in June (50.29% versus 69.00%) and December (38.00% versus 56.23%), together with higher pH and generally lower salinity. Cd accounted for 54.3-65.7% of potential ecological risk, and its single-factor index exceeded one at three sites. Mean cover and richness at Restored sites increased across age classes, from 15.8% and 1.5 species at <3 years to 64.2% and 7.0 species at 5-10 years, whereas diversity peaked in the intermediate class. Cd index, pollution load index (PLI) and potential ecological risk index (RI) did not decline monotonically with retirement age. Restored sites had lower mean metal-risk indices than Abandoned sites at 5-10 years but higher means at 3-5 years. Soil pH was positively associated with cover and richness; Cd index and PLI showed no significant associations with vegetation metrics. Discussion: These descriptive chronosequence patterns indicate that vegetation reorganisation and chemical-risk attenuation do not follow a common trajectory, and that recovery cannot be inferred from retirement age alone. Wetland retirement management should combine site-specific contamination assessment with vegetation and habitat evaluation.

Source: Frontiers in Plant Science

DOI: 10.3389/fpls.2026.1989517