The environmental impact of mask-derived microplastics on soil ecosystems.

During the COVID-19 pandemic, a significant increased number of masks were used and improperly disposed of. For example, the global monthly consumption of approximately 129 billion masks. Masks, composed of fibrous materials, can readily release microplastics, which may threaten various soil ecosystem components such as plants, animals, microbes, and soil properties. However, the specific effects of mask-derived microplastics on these components remain largely unexplored. Here, we investigated the effects of mask-derived microplastics (grouped by different concentrations: 0, 0.25, 0.5, and 1 % w/w) on soil physicochemical properties, microbial communities, growth performance of lettuce (Lactuca sativa L. var. ramosa Hort.) and earthworm (Eisenia fetida) under laboratory conditions for 80 days. Our findings suggest that mask-derived microplastics reduced soil bulk density while increasing the mean weight diameter of soil aggregates and modifying nutrient levels, including organic matter, potassium, nitrogen, and phosphorus. An increase in the abundance of denitrification bacteria (Rhodanobacteraceae) was also observed. Mask-derived microplastics were found to reduce lettuce germination, and a hormesis effect of low-concentration stimulation and high-concentration inhibition was observed on biomass, chlorophyll, and root activity. While the mortality of earthworms was not significantly affected by the mask-derived microplastics, but their growth was inhibited. Collectively, our results indicate that mask-derived microplastics can substantially impact soil properties, plant growth, and earthworm health, with potential implications for soil ecosystem functionality.

Application potential of Vaccinium ashei R. for cadmium migration retention in the mining area soil.

Despite numerous reports on phytoremediation of heavy metals contaminated soil, there are few reports on plant retention of heavy metals in the mining area slope. This study was the first of its kind to explore the cadmium (Cd) retention capacity of the blueberry (Vaccinium ashei Reade). Firstly, we investigated the stress response of blueberry to different soil Cd concentrations (1, 5, 10, 15, 20 mg/kg) to assess its potential for phytoremediation by pot experiments. The results showed that the blueberry biomass exposed to 10 and 15 mg/kg Cd was significantly increased compared with the control (1 mg/kg Cd); the blueberry crown increased by 0.40% and 0.34% in 10 and 15 mg/kg Cd-contaminated soil, respectively, compared with control; the blueberry heigh did not even change significantly in each treatment group; the total chlorophyll content, peroxidase and catalase activity of blueberry were enhanced in 5-20 mg/kg Cd treatments. Furthermore, the Cd contents of blueberry in the root, stem and leaf increased significantly as the Cd concentration of soil increased. We found that more Cd accumulated in blueberry root: the bioaccumulation concentration factor was root > stem > leaf for all groups; the residual-Cd (Cd speciation) in soil increased by 3.83%-411.11% in blueberry-planted versus unplanted groups; blueberry improved the Cd-contaminated soil micro-ecological environment including soil organic matter, available K and P, as well as microbial communities. Then, to investigate the effect of blueberry cultivation on Cd migration, we developed a bioretention model and revealed that soil Cd transport along the model slope was significantly weakened by blueberry cultivation, especially at the bottom of the model. In a word, this research suggests a promising method for the phytoremediation of Cd-contaminated soil and the reduction of Cd migration in mining areas.

Assessment about bioindicator capacity of acrocarpous moss Campylopus schmidii exposed to abandoned pyritic tailings.

Terrestrial mosses are promising species to study concerning metal deposition, absorption, and soil fertility as moss biocrusts. However, acrocarpous moss, as a kind of terrestrial mosses, has not yet been well understood, both in environmental monitoring and ecological application, especially exposed to an abandoned pyrite mining. Herein, we investigated the concentrations of different heavy metals in soil underlying acrocarpous moss Campylopus schmidii at three distances from an abandoned pyrite mine tailings (0.5, 1, 2 km) by sampling analysis, as well as the accumulation properties of heavy metals in different parts of mosses and soil nutrients under intact mosses and moss-free layers. The results indicated that the soil we researched was heavily polluted by Cr, Cu, and Cd, which was 4.46, 4.18, and 1.77 times higher than the standard of risk screening values for soil environment quality in China. And there was a marked difference in the concentrations and distribution of heavy metals in mosses, with higher concentrations of Cr, Cu, Ni and Pb mainly in the ageing parts. In addition, mosses can effectively promote soil fertility. Compared with the bare soil without the moss layer, the total organic matter and total potassium concentrations of the soil covered by the intact moss layer were significantly increased, by 113.91% and 186.08% respectively. Correlation analysis indicated that similar pollution sources for Zn, Cd, Cu, and Pb, and the concentrations of these heavy metals in soil connected with the distance from the source of pollution. Overall, we expected that these findings could assess the greater potential of single native dominant moss species C.schmidii to act as biomonitors in specific pyrite mine tailings characterized by barren soil with strong acids (pH < 4.0) and polymetallic pollution. Meanwhile, our results revealed may serve as a possibility reference for similar areas and is recommended for developing a vegetative cover utilizing local acrocarpous mosses to achieve greening of degraded tailings in the future, as well as environmental management and protection.