Synergistic physicochemical-microbial coupling of ultrafine oyster shell powder for enhanced sediment remediation

Calcium carbonate skeleton fragments and powder of marine organisms are important components of marine sediments. They might play positive ecological functions in the benthic ecosystem. The present study found that the addition of ultrafine oyster shell powder (UOSP) could raise sediment pH from 7.11 to 7.78 while notably reducing H₂S, Pb and Mn by 55.27 %, 83.92 % and 76.17 %, respectively. Additionally, UOSP further led to the alteration of bacterial community structure. RDA results revealed that pH significantly affected bacterial keystone species (P < 0.05), which occupied crucial positions in promoting the continuous carbon‑sulfur cycle, suggesting that the addition of UOSP sustained the core function of the benthic microecosystem. The wet weights of benthic animal bivalve and polychaete increased by 18.43 % and 13.98 %, respectively, due to the improved health and sedimentary environment. The present study confirms that the natural shell powder provides significant ecological benefits to the benthic ecosystem. The application of UOSP in sediment restoration is viable.