Biochar, an eco-friendly soil amendment, holds promise for remediating contaminated soils, yet its impacts on coastal wetland soils under combined microplastic (MP) and heavy metal (HM) pollution remain underexplored. This study examined the efficacy of 2% Spartina alterniflora-derived biochar (BC) in rehabilitating soils co-contaminated with cadmium (Cd) and two MPs—polyethylene (PE) and polylactic acid (PLA)—at 0.2% and 2% (w/w). The results indicated that biochar significantly elevated soil pH (8.35–8.43) and restored electrical conductivity (EC) to near-control levels, while enhancing organic matter content (up to 130% in PLA-contaminated soils), nutrient availability (e.g., phosphorus, potassium), and enzyme activity. Biochar reduced bioavailable Cd by 14–15% through adsorption and ion exchange. Although bacterial richness and diversity slightly declined, biochar reshaped microbial communities, enriching taxa linked to pollutant degradation (e.g., Proteobacteria, Bacteroidota) and upregulated functional genes associated with carbon, nitrogen, and sulfur cycling. Additionally, biochar boosted Suaeda salsa (S. salsa) biomass (e.g., 0.72 g/plant in A1B) and height (e.g., 14.07 cm in E1B) while reducing Cd accumulation (29.45% in shoots) and translocation. Remediation efficiency was most pronounced in soils with 0.2% PLA. These findings bridge critical knowledge gaps in biochar’s role in complexly polluted coastal wetlands and validate its potential for sustainable soil restoration.

Difenoconazole and imidacloprid are key components of seed-coating agents, which alter soil microbial community structure and function after application. Existing studies mainly focus on the environmental effects of their spraying application, while research on their impacts on the soil ecosystem when used as seed-coating agents is relatively limited. Through field experiments, this study systematically evaluated and compared the effects of difenoconazole and imidacloprid seed coatings on wheat rhizosphere soil microbial communities and ecological functions by measuring soil enzyme activities, employing 16S rRNA and ITS high-throughput sequencing technologies and predicting KEGG functional pathways. The results showed that imidacloprid and difenoconazole significantly reduced bacterial community diversity, particularly under the high-dosage difenoconazole treatment (0.18 g a.i./kg seed), with a 5.80% decrease in diversity by day 30. This treatment most strongly inhibited the phyla Bacteroidota and Myxococcota, with maximum reductions of 23.87% and 63.57%, respectively. However, the abundance of Actinobacteriota significantly increased, with a maximum increase of 38.53%. Additionally, fungal community diversity significantly increased under both difenoconazole and imidacloprid treatments. Both seed coatings significantly altered the microbial community structure from days 20 to 60, with recovery occurring by day 120. Furthermore, KEGG pathway analysis revealed that the high-dosage difenoconazole treatment (0.18 g a.i./kg seed) significantly activated functional pathways such as cell motility, signal transduction, and membrane transport, whereas the standard dosage (0.12 g a.i./kg seed) exhibited metabolic suppression. This study elucidates the dynamic impacts of seed-coating agent application on soil microbial communities, providing theoretical support for rational pesticide use and the optimization of agricultural strategies.

Drivers of HABs and their multilevel impacts on aquatic ecosystem structure and function.

Microplastics are persistent contaminants in coastal wetlands, yet the mechanisms of their microbial transformation remain poorly understood. This study examined the interactions between a wetland sediment-derived microbial consortium and polyethylene terephthalate (PET) fibers over a 60-day incubation. After 60 days, the consortium caused a PET weight loss of 13.7 ± 0.9%, whereas the abiotic control showed a less than 2% loss. The water contact angle decreased from 77.5 ± 1.2° to 75.8 ± 0.4°, suggesting enhanced surface hydrophilicity. Multi-scale surface analyses (SEM, WCA, and FTIR) confirmed progressive microbial colonization, increased surface roughness, and enhanced hydrophilicity through microbially mediated modification. High-throughput 16S rRNA sequencing unveiled a distinct community succession; PET exerted selective pressure that reduced alpha-diversity while enriching specific functional taxa such as Acinetobacter and Pseudomonas. Moreover, isolation and co-culture assays confirmed the importance of synergistic microbial interactions in PET transformation, with co-culture of four representative isolates causing 9.2 ± 0.1% PET weight loss, compared with only 1.7–3.2% in monocultures. These findings underscore the intrinsic natural attenuation potential of wetland ecosystems and provide a critical scientific basis for developing nature-based management strategies. By identifying key functional taxa and PET-associated transformation pathways, this work supports the establishment of early-warning mechanisms to safeguard the ecological integrity and soil health of coastal World Natural Heritage sites like the Tiaozini Wetland.

Rhizosphere microorganisms play central roles in nutrient cycling and contaminant transformation in sediment-associated freshwater systems, yet their responses to newer pesticides remain insufficiently characterized. In this study, a 28-day Vallisneria natans–rhizosphere sediment microcosm was used to compare the effects of trifluenfuronate and fluopyram at nominal concentrations of 0.01, 0.1, and 1 mg L⁻¹. Bacterial community composition was assessed using 16S rRNA gene sequencing, and shotgun metagenomic data were used to evaluate relative functional annotation patterns. Plant physiological traits and rhizosphere sediment enzyme activities were measured as ecological context for interpreting microorganism-associated responses. Fluopyram, particularly at 1 mg L⁻¹, produced clearer ordination-level shifts in rhizosphere bacterial community composition than trifluenfuronate, although pairwise treatment separation was not statistically resolved after multiple-testing correction. Annotation-based metagenomic profiles also differed between the two pesticides: stronger exposure was associated with reduced relative signals for several xenobiotic-, transport-, and regulation-related annotations, while high-dose fluopyram showed a methane-metabolism-related annotation signal and high-dose trifluenfuronate showed relative enrichment of secondary-metabolism-related annotations. These microbial and annotation-profile responses coincided with stronger inhibition of V. natans growth and greater suppression of rhizosphere sediment enzyme activities under fluopyram exposure. Overall, fluopyram induced more consistent microorganism-associated response patterns than trifluenfuronate in the tested rooted macrophyte–sediment microcosm. The results highlight the sensitivity of rhizosphere microbial communities and metagenomic annotation profiles to pesticide exposure in sediment-associated freshwater systems.