Ubiquity and ecological risks of conjugated steroids cannot be overlooked: First evidence from estuarine sediments.

Steroids, renowned for endocrine-disrupting capabilities, have garnered significant research interest, predominantly centered on their parent forms. This study was the first to explore the composition, spatiotemporal characteristics, sources, mass inventories, and ecological risks of steroids in free and conjugated forms in estuarine sediments. Seventeen steroids were identified in sediments with the total levels of 1.3-4.3 ng/g. Most natural steroids and metabolites existed in free forms, while synthetic ones predominantly stored in conjugates. Environmental factors exerted limited impacts on steroid distribution. Raw domestic wastewater, drug consumption, and mariculture may be leading steroid sources in estuarine sediments, with total mean mass inventories of 177-219 µg/m2. The predominant contributors to the ecological risk were cortisol, prednisolone, 20α-dihydroprogesterone, 20ß-dihydroprogesterone, and progesterone. This research gives the first insight into the understanding of conjugated steroids in the marine environment, and advocates for more studies on the fate and ecotoxicology of conjugated steroids.

Distribution and typologies of anthropogenic seafloor litter in the Pearl River Estuary and adjacent coastal waters, China.

Marine litter pollution poses a significant threat to offshore ecosystems, eliciting widespread concern. We investigated seafloor litter patterns in the Pearl River Estuary and adjacent coastal waters of China in 2023 via bottom trawl survey. Average number and weight densities were found to be 154.34 ± 30.95 n/km2 and 2384.63 ± 923.98 g/km2, respectively. Plastic was the most abundant material by number density (79.07 %), and rubber the highest by weight density (22.93 %). Overall number density varied from 40.50 ± 22.50 to 221.13 ± 52.44 n/km2, with the highest in Daya Bay and the lowest in Guanghai Bay. Weight density varied from 189.93 ± 71.94 to 5386.70 ± 3050.30 g/km2, with the highest in Qiao Island and the lowest in Honghai Bay. The main source was plastic bags and wrappers. The Pearl River Delta and Daya Bay were identified as seafloor litter distribution hotspots. Controlling plastic waste input is crucial for reducing seafloor litter in the Pearl River Estuary.

Effects of di-n-butyl phthalate on gills- and liver-specific EROD activities and CYP1A levels in juvenile red snapper (Lutjanus argentimaculatus).

Di-n-butyl phthalate, one of the most easily detected pollutants of phthalate esters in the environment, has been added to the priority list of hazardous substances by many countries. As one of low molecular weight phthalates, Di-n-butyl phthalate may have a great adverse potency on various aquatic organisms. In this study, the juvenile red snapper, Lutjanus argentimaculatus, was exposed to the concentrations of Di-n-butyl phthalate (20 µg L-1, 100 µg L-1 and 500 µg L-1) for 15 days. EROD activities and CYP1A levels were measured in liver and gill tissues. In gills, the similar effect has been found to inhibit or induce EROD activities and CYP1A levels, and there existed a good correlation between them. Whereas in the case of the liver, a moderate correlation was observed between EROD activities and CYP1A levels, which was mainly due to the inhibited EROD activities and the CYP1A levels with no significant difference by day 15. In conclusion, this study revealed the similar and different effects of cytochrome P450 enzymes on fish in the time-, concentration-, and tissue-dependent Di-n-butyl phthalate exposure. Furthermore, as the adverse effects indicated between CYP1A levels and EROD activities, metabolic mechanisms of phthalates in different tissues should be highly emphasized in future studies.