Sediment is the ultimate sink of environmental pollutants. A total of 128 surface sediment samples were collected from 8 rivers and 3 reservoirs in Maoming City, Guangdong Province. This study assessed the content and distribution of brominated flame retardants in sediments. The acute toxicity effects of tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDs) in sediments were evaluated using Caenorhabditis elegans as model organisms. The concentration of TBBPA in sediments ranged from not detected (ND) to 12.59 pg/kg and was mainly distributed in the central area, which was affected by the emission of TBBPA from residential and factory. The concentration of HBCDs ranged from ND to 6.31 pg/kg, and the diastereoisomer distribution was consistent, showing a trend close to the South China Sea. The composition pattem of HBCDs in the surface sediments from rivers were 41.73%62.33%, 7.89%-25.54%, and 18.76%-40.65% for a-, /3-, and y-HBCD, respectively, and in the sediments from reservoirs were 26.15%-45.52%, 7.44%-19.23%, and 47.04%-61.89% for a-, /3-, and y-HBCD, respectively. When the sum of concentrations of TBBPA and HBCD in sediments were above high levels, reactive oxygen species in nematodes significantly increased, resulting in an oxidative stress response. Intestinal permeability was also enhanced, causing intestinal damage. In addition, in terms of this study, TBBPA had a greater impact on biotoxicity compared to HBCDs, and more attention should be paid to the toxic effects of the river ecosystem organisms in Maoming City, Guangdong Province. This study can complement the pollution database in the study area and provide basic data for pollution control. (c) 2024 The Research Center for Eco-Environmental Sciences, Chinese Academy of

During the COVID-19 pandemic, an abundance of plastic face masks has been consumed and disposed of in the environment. In addition, substantial amounts of plastic mulch film have been used in intensive agriculture with low recovery. Butyl benzyl phthalate (BBP) and TiO2 nanomaterials (nTiO2) are widely applied in plastic products, leading to the inevitable release of BBP and nTiO2 into the soil system. However, the impact of coexposure of BBP and nTiO2 at low concentrations on earthworms remains understudied. In the present study, transcriptomics was applied to reveal the effects of individual BBP and nTiO2 exposures at a concentration of 1 mg kg -1, along with the combined exposure of BBP and nTiO2 (1 mg kg -1 BBP + 1 mg kg -1 nTiO2 (anatase)) on Metaphire guillelmi. The result showed that BBP and nTiO2 exposures have the potential to induce neurodegeneration through glutamate accumulation, tau protein, and oxidative stress in the endoplasmic reticulum and mitochondria, as well as metabolism dysfunction. The present study contributes to our understanding of the toxic mechanisms of emerging contaminants at environmentally relevant levels and prompts consideration of the management of BBP and nTiO2 within the soil ecosystems.