Microplastic inhibits the sorption of trichloroethylene on modified biochar.

Biochar (BC) was used to remove trichloroethylene (TCE) from soil and water phases, and BC modification changed the sorption behavior of pollutants. Microplastics are emerging pollutants in the soil and water phases. Whether microplastics can affect the sorption of TCE by modified BC is not clear. Thus, batch sorption kinetics and isotherm experiments were conducted to elucidate the sorption of TCE on BC, and BC combined with polyethylene (PE) or polystyrene (PS). The results showed that HCl and NaOH modification increased TCE sorption on BC, while HNO3 modification inhibited TCE sorption on BC. When PE/PS and BC coexisted, the TCE sorption capacity decreased significantly on BC-CK + PE, BC-HCl + PE, BC-HNO3 + PE, BC-NaOH + PE, and BC-NaOH + PS, which was likely due to the preferential sorption of PE/PS on BC samples. We concluded that microplastics can change TCE sorption behavior and inhibit TCE sorption on BC samples. Thus, the interaction of BC and microplastics should be considered when BC is used for TCE removal in soil and water remediation.

Coordinated responses of rice (Oryza sativa) to the stresses of benzotriazole ultraviolet stabilizers (BZT-UVs): Antioxidative system, photosynthetic activity, and metabolic regulation.

Massive use of plastic products has caused their accumulation in soils, releasing large amounts of endogenous plastic additives (e.g., benzotriazole ultraviolet stabilizers, in short BZT-UVs) into terrestrial ecosystems. However, their plant toxicity is little known. Herein, we investigated the occurrence of BZT-UVs in contaminated farmland and selected three BZT-UV congeners to explore their toxic effects on the antioxidant, photosynthetic, and metabolic perturbation on rice (Oryza sativa). Results showed that the mean concentrations of ∑BZT-UVs in soil and plant samples were 180.7 ng/g dw and 156.4 ng/g dw, respectively. UV-P, UV-327 and UV-328 were the dominant BZT-UV congeners in both of soils and plants. Three BZT-UV congeners caused oxidative damages to rice in a dose-dependent manner, especially for UV-328. Functional genes involved in chlorophyll synthetases was inhibited by over 50 % under the stress of BZT-UVs, whereas those responsible for chlorophyll degradation were obviously promoted. The chlorophyll content was thus decreased, leading to a weakened photosynthesis system and an unbalanced carbon metabolism. The transcriptome and metabolome proved that the flux of carbohydrate metabolism and amino acid metabolism were obviously promoted in plants induced by BZT-UVs, which could inhibit the growth of rice. These findings offered insights into the coordinated responses of plants and advanced our understanding of potential ecological risks of BZT-UVs to terrestrial ecosystems.

In-situ enrichment of ARGs and their carriers in soil by hydroxamate siderophore: A promising biocontrol approach for source reduction.

Pathogenic microorganisms with antibiotic resistance genes (ARGs) pose a serious threat to public health and soil ecology. Although new drugs and available antibacterial materials can kill ARG carriers but accidentally kill beneficial microorganisms. Therefore, the rapid enrichment and separation of ARGs and their carriers from soil is becoming an important strategy for controlling the diffusion of ARGs. Hydroxamate siderophore (HDS) has gained widespread attentions for its involvement in trace element transfer among microorganisms in the soil environment, we thus explored an in-situ trapping-enrichment method for ARGs and their carriers via a small molecular HDS secreted by Pseudomonas fluorescens HMP01. In this study, we demonstrate that HDS significantly in-situ traps and enriches certain ARGs, including chloramphenicol, MLS, rifamycin, and tetracycline resistance genes in the soil environment. The enrichment efficiencies were 1473-fold, 38-fold, 17-fold, and 5-fold, respectively, higher than those in the control group. Specifically, the primary enriched ARGs were rpoB, mphL, catB2, and tetA(60), and Bacillus, Rhizobium, Rossellomorea, and Agrobacterium were hosts for these ARGs. This enrichment was caused by the upregulation of chemotaxis genes (e.g., cheW, cheC, and cheD) and rapid biofilm formation within the enriched bacterial population. Notably, representative ARGs such as cat, macB, and rpoB were significantly reduced by 36%, 85.7%, and 72%, respectively, in the paddy soil after HDS enrichment. Our research sheds light on the potential application of siderophore as a rapping agent for the eco-friendly reduction of ARGs and their carriers in soil environments.