Source Apportionment, Hydrodynamic Influence, and Environmental Stress of Pharmaceuticals in a Microtidal Estuary with Multiple Outlets in South China.

Pharmaceutical residues in the environment are of great concern as ubiquitous emerging contaminants. This study investigated the presence of 40 pharmaceuticals in water and sediment of the Pearl River Estuary (PRE) in the wet season of 2020. Among psychiatric drugs, only diazepam was found in water samples while six of them were detected in the sediment. The Σantibiotics levels ranged from 6.18 to 35.9 ng/L and 2.63 to 140 ng/g dry weight in water and sediment samples, respectively. Fluoroquinolones and tetracyclines were found well settling in the outlet sediment, while sulfonamides could be released from disturbed sediment under stronger tidal wash-out conditions. After entering the marine waters, pharmaceuticals tended to deposit at the PRE mouth by the influence of the plume bulge and onshore invasion of deep shelf waters. Low ecological risks to the aquatic organisms and of causing antimicrobial resistance were identified. Likewise, hydrological modeling results revealed insignificant risks: erythromycin-H2O and sulfamethoxazole discharged through the outlets constituted 30.8% and 6.74% of their environmental capacity, respectively. Source apportionment revealed that pharmaceutical discharges through the Humen and Yamen outlets were predominantly of animal origin. Overall, our findings provide strategic insights on environmental regulations to further minimize the environmental stress of pharmaceuticals in the PRE.

Magnetic natural lipid nanoparticles for oral treatment of colorectal cancer through potentiated antitumor immunity and microbiota metabolite regulation.

The therapeutic efficacy of oral nanotherapeutics against colorectal cancer (CRC) is restricted by inadequate drug accumulation, immunosuppressive microenvironment, and intestinal microbiota imbalance. To overcome these challenges, we elaborately constructed 6-gingerol (Gin)-loaded magnetic mesoporous silicon nanoparticles and functionalized their surface with mulberry leaf-extracted lipids (MLLs) and Pluronic F127 (P127). In vitro experiments revealed that P127 functionalization and alternating magnetic fields (AMFs) promoted internalization of the obtained P127-MLL@Gins by colorectal tumor cells and induced their apoptosis/ferroptosis through Gin/ferrous ion-induced oxidative stress and magneto-thermal effect. After oral administration, P127-MLL@Gins safely passed to the colorectal lumen, infiltrated the mucus barrier, and penetrated into the deep tumors under the influence of AMFs. Subsequently, the P127-MLL@Gin (+ AMF) treatment activated antitumor immunity and suppressed tumor growth. We also found that this therapeutic modality significantly increased the abundance of beneficial bacteria (e.g., Bacillus and unclassified-c-Bacilli), reduced the proportions of harmful bacteria (e.g., Bacteroides and Alloprevotella), and increased lipid oxidation metabolites. Strikingly, checkpoint blockers synergistically improved the therapeutic outcomes of P127-MLL@Gins (+ AMF) against orthotopic and distant colorectal tumors and significantly prolonged mouse life spans. Overall, this oral therapeutic platform is a promising modality for synergistic treatment of CRC.

Significant riverine inputs of typical plastic additives-phthalate esters from the Pearl River Delta to the northern South China Sea.

Phthalate esters (PAEs) are representative additives used extensively in plastics. In this study, 15 PAEs were investigated at the eight riverine outlets of the Pearl River Delta (PRD). The total concentrations of Σ15PAEs, including both the dissolved and particulate phases, ranged from 562 to 1460 ng/L and 679 ng/L-2830 ng/L in the surface and bottom layers, respectively. Dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) dominated in the dissolved and suspended particulate matter (SPM) phases, respectively, accounting for >50 % and > 80 % of Σ15PAEs. Riverine input of wastewater from the PRD was possibly the primary source of the contamination. Higher levels of PAEs occurred at the eastern outlets than at the western ones. The dissolved and particulate PAEs varied seasonally, with significantly higher concentrations observed in the dry season than in the wet season. However, no significant differences of PAE levels in both phases were observed among low, medium, and high tides. The partitioning results demonstrated that SPM is important in the transportation of pollutants in estuaries, where more hydrophobic DEHP was predominantly transported by the SPM phase, while those more hydrophilic ones were regularly transported by the dissolved phase. The total annual flux of Σ15PAEs through the eight outlets to the SCS reached 1390 tons.

Occurrence, spatial distribution, and partitioning behavior of marine lipophilic phycotoxins in the Pearl River Estuary, South China.

The occurrence, spatial distribution, and partitioning behavior of 17 marine lipophilic phycotoxins (MLPs) in surface and bottom seawater, particulate organic matter (POM), and surface sediment from the Pearl River Estuary (PRE) were investigated to understand current contamination and the potential risks to marine ecosystems in this region. Nine MLPs were detected, including azaspiracid1-3, gymnodimine, okadaic acid, dinophysistoxin 1-2, pectenotoxin2 (PTX2), and homoyessotoxin, with Σ17MLP concentrations ranging 545-12,600 pg L-1 and 619-8,800 pg L-1 in surface and bottom seawater, respectively; 0-294 ng g-1 and 0.307-300 ng g-1 dry weight (dw) in surface and bottom POM, respectively; and 3.90-982 pg g-1 dw in surface sediment. Lower Σ17MLP levels in the seawater were found at the mouth of the PRE, and gradually increased with increasing distance offshore. According to the calculated partition coefficient, the affinity of MLPs for the aquatic environment components was as follows (from highest to lowest): POM > seawater > sediment. Overall, the distribution and migration of MLPs in the PRE may depend on partition coefficients, the organic carbon fraction, and environmental factors.

Unraveling microbe-mediated degradation of lignin and lignin-derived aromatic fragments in the Pearl River Estuary sediments.

Estuaries are one of the most crucial areas for the transformation and burial of terrestrial organic carbon (TerrOC), playing an important role in the global carbon cycle. While the transformation and degradation of TerrOC are mainly driven by microorganisms, the specific taxa and degradation processes involved remain largely unknown in estuaries. We collected surface sediments from 14 stations along the longitudinal section of the Pearl River Estuary (PRE), P. R. China. By combining analytical chemistry, metagenomics, and bioinformatics methods, we analyzed composition, source and degradation pathways of lignin/lignin-derived aromatic fragments and their potential decomposers in these samples. A diversity of bacterial and archaeal taxa, mostly those from Proteobacteria (Deltaproteobacteria, Gammaproteobacteria etc.), including some lineages (e.g., Nitrospria, Polyangia, Tectomicrobia_uc) not previously implicated in lignin degradation, were identified as potential polymeric lignin or its aromatic fragments degraders. The abundance of lignin degradation pathways genes exhibited distinct spatial distribution patterns with the area adjacent to the outlet of Modaomen as a potential degradation hot zone and the Syringyl lignin fragments, 3,4-PDOG, and 4,5-PDOG pathways as the primary potential lignin aromatic fragments degradation processes. Notably, the abundance of ferulic acid metabolic pathway genes exhibited significant correlations with degree of lignin oxidation and demethylation/demethoxylization and vegetation source. Additionally, the abundance of 2,3-PDOG degradation pathways genes also showed a positive significant correlation with degree of lignin oxidation. Our study provides a meaningful insight into the microbial ecology of TerrOC degradation in the estuary.