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

Although more attention has been paid to microplastics (MPs) pollution in environment, research on the synthetic influence of microplastic and heavy metals remains limited. To help fill this information gap, we investigated the adsorption behavior of virgin polyvinyl chloride microplastics (PVCMPs) (<= 450 mu m white spherical powder) on cadmium (II). The effects on seed germination, seedling growth, photosynthetic system, oxidative stress indicators of lettuce, and changes in Cd bioavailability were evaluated under Cd2+ (25 mu mol/L), PVCMPs (200 mg/L), and PVCMP-Cd combined (200 mg/L + 25 mu mol/L) exposures in hydroponic system. The results demonstrated that the PVCMPs effectively adsorbed Cd ions, which validated by the pseudo-second-order kinetic and the Langmuir isotherm models, indicating the sorption of Cd2+ on the PVCMPs was primary chemisorption and approximates monomolecular layer sorption. Compared to MPs, Cd significantly inhibits plant seed germination and seedling growth and development. However, Surprising improvement in seed germination under PVCMPs-Cd exposure was observed. Moreover, Cd2+ and MPs alone or combined stress caused oxidative stress with reactive oxygen species (ROS) including H2O2, O2- and Malondialdehyde (MDA) accumulation in plants, and substantially damaged to photosynthesis. With the addition of PVCMPs, the content of Cd in the leaves significantly (P<0.01) decreased by 1.76-fold, and the translocation factor and Cd(2+)removal rate in the water substantially (P<0.01) decreased by 6.73-fold and 1.67-fold, respectively in contrast to Cd2+ stress alone. Therefore, it is concluded the PVCMP was capable of reducing Cd contents in leaves, alleviating Cd toxicity in lettuce. Notably, this study provides a scientific foundation and reference for comprehending the toxicological interactions between microplastics and heavy metals in the environment.

Microplastic (MPs) pollution is a major global agroecosystem issue. Microplastic (<= 0.2 mu m) are mainly uptake by roots and transferred to the edible part of the crop, which also can be absorbed by the leaf. MPs and its extractum seriously impact crop growth and development, yield, and quality. We discuss the evidence and integrate omics studies to explore the adverse effects of MPs. The harmful impacts on crops mainly include decreasing crops' germination and photosynthesis intensity, reducing crops' biomass and the yield of edible parts, lipid peroxidation damage, changing in crop metabolic system, disrupting crop carbon and nitrogen metabolism, inducing chromosomal aberrations and DNA damage. In addition, MPs can change the species composition and community structure of soil root microorganisms, indirectly affecting crops' growth and development. The toxicity depends on the materials type, particle size, and concentration of MPs. Crops can resist the toxicity of MPs by enhancing the antioxidant system's function and generating more organic acids and other secretions from roots. We also analyzed the benefits and drawbacks of the current experimental methods used to study MPs' effects on crops. Last, we point out the shortcomings existing in the research on the interaction between MPs and crops and put forward the direction and focus of future research. In the future, we should strengthen field experiments and consider the complex environment of soil. This review can offer a theoretical and scientific foundation for controlling and preventing MPs pollution in agro-ecosystem.