Safe utilization evaluation of two typical traditional Chinese medicinal materials in Cd-contaminated soil based on the analysis of Cd transfer and AHP model

Effects of microplastics on black soil health: A global meta-analysis

Microplastics (MPs) have garnered widespread attention as an emerging global contaminant. However, the impacts of MPs on black soil health remain unclear. A meta-analysis of 337 cases from 33 studies was conducted to elucidate the effects of MPs on black soil health. The analysis incorporated 35 indicators, including soil properties, soil enzymes, plant growth, soil animal health, and soil microbial diversity. We investigated the effects of MPs properties, such as particle type, size, concentration, and exposure duration, on soil health. Results showed that MPs led to notable increases in SOM, DOC, available nitrogen by 31.84 %, 14.35 %, and 12.45 %, respectively, while decreasing nitrate nitrogen by 12.89 %. In addition, MPs exposure enhanced soil urease activity by 11.24 % but reduced phosphatase activity by 6.62 %. MPs also diminished microbial alpha-diversity, caused oxidative damage in earthworms, and suppressed plant germination rates. Notably, smaller MPs, higher concentrations, longer exposure periods, and conventional MPs have more detrimental effects on soil health. By applying the entropy weight method combined with the analytical hierarchy process, we quantified the overall impact of MPs on black soil health as a 12.09 % decrease. Our findings underscore the risks of persistent MPs pollution to black soil health.

Biochar and Trehalose Co-Application: A Sustainable Strategy for Alleviating Lead Toxicity in Rice

Lead (Pb) is a common contaminant that causes serious health and environmental problems. Thus, appropriate environmentally friendly and efficient techniques must be developed to remediate Pb in soils. Biochar (BC) has shown promise as an effective strategy to mitigate Pb toxicity. Trehalose (Tre) is a promising sugar that has been shown to effectively improve plant tolerance to abiotic stresses. Nonetheless, its role in alleviating Pb toxicity is unknown. The study investigated the impacts of BC and Tre co-application in alleviating Pb toxicity in rice crops. The study included the following treatments: control, Pb stress (250 mg kg-1), Pb stress (250 mg kg-1) + BC (2.5%), Pb stress (250 mg kg-1) + Tre (30 mM), and Pb stress (250 mg kg-1) + BC (2.5%) + Tre (30 mM). Results showed that Pb toxicity reduced rice yield by decreasing chlorophyll synthesis and relative water content (RWC), by increasing malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents, Pb accumulation in roots and shoots, soil available Pb concentration, and by decreasing the availability of soil nutrients. BC and Tre application mitigated the adverse impacts of Pb; however, more promising results were obtained with the co-application of BC and Tre. The results indicated that co-application of BC and Tre increased the rice yield by increasing photosynthetic pigments (46-96.42%), leaf water contents (16.67%), proline and soluble protein synthesis (35.13% and 24.96%), and antioxidant activities (12.07-31.67%), by decreasing root (59.72%), shoot (76.47%), and soil (57.14%) Pb concentrations, and the Pb translocation factor (15.08%). These findings suggested that co-application of BC and Tre can be a practical approach for reducing Pb toxicity, availability, and uptake, which improves rice productivity in Pb-polluted soil.

Cadmium toxicity in blueberry cultivation and the role of arbuscular mycorrhizal fungi

Cadmium (Cd) is a toxic heavy metal that interferes with essential metabolic pathways crucial for plant growth, often resulting in toxicity and plant death. Blueberry plants exhibit metabolic adaptations to mitigate the stress caused by elevated Cd levels. In this review, we highlighted the effects of Cd-induced stress on blueberry plants and explored the potential alleviating effects of arbuscular mycorrhizal fungi (AMF). Cd uptake disrupts plant metabolism and impacts primary and secondary metabolites, including anthocyanins, which play a role in defense mechanisms against pathogens. Hence, Cd-induced stress alters anthocyanin levels in blueberry leaves, negatively affecting antioxidant defense mechanisms and hindering growth. Conversely, AMF establishes a symbiotic relationship with blueberry plants, promoting nutrient absorption and enhancing stress tolerance. Understanding the association between Cd stress, anthocyanin responses in blueberries, and AMF-mediated mitigation is crucial for developing integrated strategies to enhance blueberry plant health and improve quality. Employing AMF to remediate metal-related stress represents a significant breakthrough for sustainable crop production in a Cd-contaminated environment.

Micro/nanoplastics pollution poses a potential threat to soil health

Micro/nanoplastic (MNP) pollution in soil ecosystems has become a growing environmental concern globally. However, the comprehensive impacts of MNPs on soil health have not yet been explored. We conducted a hierarchical meta-analysis of over 5000 observations from 228 articles to assess the broad impacts of MNPs on soil health parameters (represented by 20 indicators relevant to crop growth, animal health, greenhouse gas emissions, microbial diversity, and pollutant transfer) and whether the impacts depended on MNP properties. We found that MNP exposure significantly inhibited crop biomass and germination, and reduced earthworm growth and survival rate. Under MNP exposure, the emissions of soil greenhouse gases (CO2, N2O, and CH4) were significantly increased. MNP exposure caused a decrease in soil bacteria diversity. Importantly, the magnitude of impact of the soil-based parameters was dependent on MNP dose and size; however, there is no significant difference in MNP type (biodegradable and conventional MNPs). Moreover, MNPs significantly reduced As uptake by plants, but promoted plant Cd accumulation. Using an analytical hierarchy process, we quantified the negative impacts of MNP exposure on soil health as a mean value of -10.2% (-17.5% to -2.57%). Overall, this analysis provides new insights for assessing potential risks of MNP pollution to soil ecosystem functions.

Vertical migration behavior simulation and prediction of Pb and Cd in co-contaminated soil around Pb-Zn smelting slag site

Heavy metal migration in soil poses a serious threat to the soil and groundwater. Understanding the migration pattern of heavy metals (HMs) under different factors could provide a more reasonable position for pollution evaluation and targetoriented treatment of soil heavy metal. In this study, the migration behavior of Pb and Cd in co-contaminated soil under different pH and ionic strength (NaCl concentration) was simulated using convective dispersion equation (CDE). We predicted the migration trends of Pb and Cd in soils after 5, 10, and 20 years via PHREEQC. The results showed that the migration time of Cd in the soil column experiment was about 60 days faster than that of Pb, and the migration trend was much steeper. The CDE was proved to describe the migration behavior of Pb and Cd (R2 > 0.75) in soil. The predicted results showed that Cd migrated to 15-20 cm of soil within 7 years and Pb stayed mainly in the top 0-6 cm of soil within 5 years as the duration of irrigation increased. Overall, our study is expected to provide new insight into the migration of heavy metal in soil ecosystems and guidance for reducing risk of heavy metal in the environment.

Meta-analysis of impacts of microplastics on plant heavy metal(loid) accumulation

The co-occurrence of microplastics (MPs) and heavy metal(loid)s (HMs) has attracted growing scientific interest because of their wide distribution and environmental toxicity. Nevertheless, the interactions between MPs and HMs in soil-plant systems remain unclear. We conducted a meta-analysis with 3226 observations from 87 independent studies to quantify the impact of MPs addition on the plant biomass and HMS accumulation. Co-occurrence of MPs and HMs (except for As) induced synergistic toxicity to plant growth. MPs promoted their uptake in the shoot by 11.0% for Cd, 30.0% for Pb, and 47.1% for Cu, respectively. In contrast, MPs caused a significant decrease (22.6%, 17.9-26.9%) in the shoot As accumulation. The type and dose of MPs were correlated with the accumulation of HMs. MPs increased available concentrations of Cd, Pb, and Cu, but decreased available As concentration in soils. Meanwhile, MPs addition significantly lowered soil pH. These findings may provide explanations for MPs-mediated effects on influencing the accumulation of HMs in plants. Using a machine learning approach, we revealed that soil pH and total HMs concentration are the major contributors affecting their accumulation in shoot. Overall, our study indicated that MPs may increase the environmental risks of HMs in agroecosystems, especially metal cations.

Silicon reduces toxicity and accumulation of arsenic and cadmium in cereal crops: A meta-analysis, mechanism, and perspective study

Arsenic (As) and cadmium (Cd) are two toxic metal(loid)s that pose significant risks to food security and human health. Silicon (Si) has attracted substantial attention because of its positive effects on alleviating the toxicity and accumulation of As and Cd in crops. However, our current knowledge of the comprehensive effects and detailed mechanisms of Si amendment is limited. In this study, a global meta-analysis of 248 original articles with over 7000 paired observations was conducted to evaluate Si-mediated effects on growth and As and Cd accumulation in rice (Oryza sativa L.), wheat (Triticum aestivum L.), and maize (Zea mays L.). Si application increases the biomass of these crops under As and/or Cd contamination. Si amendment also decreased shoot As and Cd accumulation by 24.1 % (20.6 to 27.5 %) and 31.9 % (29.0 to 31.9 %), respectively. Furthermore, the Si amendment reduced the human health risks posed by As (2.6 %) and Cd (12.9 %) in crop grains. Si-induced inhibition of Cd accumulation is associated with decreased Cd bioavailability and the downregulation of gene expression. The regulation of gene expression by Si addition was the driving factor limiting shoot As accumulation. Overall, our analysis demonstrated that Si amendment has great potential to reduce the toxicity and accumulation of As and/or Cd in crops, providing a scientific basis for promoting food safety globally.

Interaction of microplastics with heavy metals in soil: Mechanisms, influencing factors and biological effects

Microplastics (MPs) and heavy metals (HMs) in soil contamination are considered an emerging global problem that poses environmental and health risks. However, their interaction and potential biological effects remain unclear. Here, we reviewed the interaction of MPs with HMs in soil, including its mechanisms, influencing factors and biological effects. Specifically, the interactions between HMs and MPs mainly involve sorption and desorption. The type, aging, concentration, size of MPs, and the physicochemical properties of HMs and soil have significant impacts on the interaction. In particular, MP aging affects specific surface areas and functional groups. Due to the small size and resistance to decomposition characteristics of MPs, they are easily transported through the food chain and exhibit combined biological effects with HMs on soil organisms, thus accumulating in the human body. To comprehensively understand the effect of MPs and HMs in soil, we propose combining traditional experiments with emerging technologies and encouraging more coordinated efforts.

Unlocking hormesis and toxic effects induced by cadmium in Polygonatum cyrtonema Hua based on morphology, physiology and metabolomics

Traditional Chinese medicine materials (TCMMs) are widely planted and used, while cadmium (Cd) is a widespread pollutant that poses a potential risk to plant growth and human health. However, studies on the influences of Cd on TCMMs have been limited. Our study aims to reveal the antioxidation-related detoxification mechanism of Polygonatum cyrtonema Hua under Cd stress based on physiology and metabolomics. The results showed that Cd0.5 (total Cd: 0.91 mg/kg; effective Cd: 0.45 mg/kg) induced hormesis on the biomass of roots, tubers and aboveground parts with increases of 22.88%, 27.12% and 17.02%, respectively, and significantly increased the flavonoids content by 57.45%. Additionally, the metabolism of caffeine, glutamine, arginine and purine was upregulated to induce hormesis in Cd0.5, which enhanced the synthesis of resistant substances such as spermidine, choline, IAA and saponins. Under Cd2 stress, choline and IAA decreased, and fatty acid metabolites (such as peanut acid and linoleic acid) and 8-hydroxyguanosine increased in response to oxidative damage, resulting in a significant biomass decrease. Our findings further reveal the metabolic process of detoxification by antioxidants and excessive Cd damage in TCMMs, deepen the understanding of detoxification mechanisms related to antioxidation, and enrich the relevant theories of hormesis induced by Cd.