Accumulation of micro-plastics (MPs) in the environment has resulted in various ecological and health concerns. Nowadays, however, studies are mainly focused on toxicity of MPs on aquatic organisms, but only a few studies assess the toxic effects of micro-plastics on terrestrial plants, especially edible agricultural crops. The present study was aimed to investigate the adverse effects of polyethylene (PE) microplastics on the germination of two common food crops of China, i.e., soybean (Glycine max) and mung bean (Vigna radiata). Both the crops were treated with polyethylene microplastics (PE-MPs) of two sizes (6.5 μm and 13 μm) with six different concentrations (0, 10, 50, 100, 200, and 500 mg/L). Parameters studied were (i) seed vigor (e.g., germination energy, germination index, vigor index, mean germination speed, germination rate); (ii) morphology (e.g., root length, shoot length) and (iii) dry weight. It was found that the phyto-toxicity of PE-MPs to soybean (Glycine max) was greater than that of mung bean (Vigna radiata). On the 3rd day, the dry weight of soybean was inhibited at different concentrations as compared to the control and the inhibition showed decline with the increase in the concentration of PE-MPs. After the 7th day, the root length of soybean was inhibited by PE-MPs of 13 μm size, and the inhibition degree was positively correlated with the concentration, whereas the root length of mung bean was increased, and the promotion degree was positively correlated with the concentration. Present study indicated the necessity to explore the hazardous effects of different sizes of PE-MPs on the growth and germination process of agricultural crops. Additionally, our results can provide theoretical basis and data support for further investigation on the toxicity of PE-MPs to soybean and mung bean.

The polystyrene micro-plastics (Ps-MPs) is one of the leading pollutants found in both aquatic and terrestrial ecosystems. While most of the studies on the morphology and cyto-toxicity of MPs have been based on aquatic organisms, their effects on terrestrial plants are still scarcely known. The present study was an attempt to measure the effect of different sizes (80, 100, 200, 500, 1000, 2000, 4000, and 8000 nm) and concentrations (100 and 400 mg/L) of Ps-MPs on the root length and chromosomes of root tip cells of Allium cepa using A. cepa root chromosomal aberration assay. Large size Ps-MPs (4000 and 8000 nm) showed the highest reduction in A. cepa root length; however, the differences were not significant (at p ≤ 0.05), with respect to negative control (Milli-Q water). The mitotic index showed both significant size- and concentration-dependent decreases, being the lowest (12.06%) in 100 nm at 100 mg/L concentration, with respect to the control (25.05%). The chromosomal abnormality index (CAI) and nuclear abnormality index (NAI) showed significant decreases, with respect to negative control. In addition, the induction of micro-nucleated cells was also observed in Allium root tip cells, when treated with MPs of all sizes, which can predict direct DNA damage to the plant cells. Hence, we conclude that most of the MP sizes caused cyto-toxic and nuclear damage by adversely impacting the spindle formation and induction of micro-nucleated cells in Allium cepa root tip cells. To the best of our knowledge, this is the first study that showed the effect of considerable size range of Ps-MP sizes on the root length and cell division in plants.

The widespread application of micro-plastics (MP) and their release in the open environment has become a matter of worldwide concern. When interacting with contaminants such as heavy metals in the soil ecosystem, MPs can result in detrimental effects on the soil environment and plant growth and development. However, information based on the interaction between MPs and heavy metals and their effects on terrestrial plants is still limited. Keeping this in mind, the present study was conducted to explore the single and combined toxicity of polypropylene (PP) MPs (13 and 6.5 μm) and cadmium (Cd) on germination indices; root and stem growth; fresh and dry weight; and anti-oxidative enzyme activities of rice (Oryza sativa L.) seedlings. Our results indicated that a single application of PP MP and Cd on rice seedlings inhibited most of the germination indicators, while their co-occurrence (PP + Cd) showed a reduction in the overall toxicity to some extent. A single application of both the contaminants significantly inhibited root length, stem length, fresh weight and the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) enzymes in rice seedling, while no significant effect on dry weight was observed. The combined toxicity of both PP and Cd revealed that 13 μm PP + Cd had an antagonistic effect on the growth of rice seedlings, while 6.5 μm PP + Cd showed a synergistic effect. The present study revealed that smaller PP MP particles (6.5 µm) prominently affected plant growth more as compared to larger particles (13 µm). Our work reported the combined effect of PP MP and Cd on the germination and growth of rice for the first time. This study can provide the basis for future research on the combined effects of different types and sizes of MPs and heavy metals on the terrestrial ecosystem.

The present study was planned to explore the pollution characteristics, health risks, and influence of atmospheric fine particulate matter (PM_2.5) and its components on blood routine parameters in a typical industrial city (Xinxiang City) in China. In this study, 102 effective samples 28 (April–May), 19 (July–August), 27 (September–October), 28 (December–January) of PM_2.5 were collected during different seasons from 2017 to 2018. The water-soluble ions and metal elements in PM_2.5 were analyzed via ion chromatography and inductively coupled plasma–mass spectrometry. The blood routine physical examination parameters under different polluted weather conditions from January to December 2017 and 2018, the corresponding PM_2.5 concentration, temperature, and relative humidity during the same period were collected from Second People’s Hospital of Xinxiang during 2017–2018. Risk assessment was carried out using the generalized additive time series model (GAM). It was used to analyze the influence of PM_2.5 concentration and its components on blood routine indicators of the physical examination population. The “mgcv” package in R.3.5.3 statistical software was used for modeling and analysis and used to perform nonparametric smoothing on meteorological indicators such as temperature and humidity. When Akaike’s information criterion (AIC) value is the smallest, the goodness of fit of the model is the highest. Additionally, the US EPA exposure model was used to evaluate the health risks caused by different heavy metals in PM_2.5 to the human body through the respiratory pathway, including carcinogenic risk and non-carcinogenic risk. The result showed that the air particulate matter and its chemical components in Xinxiang City were higher in winter as compared to other seasons with an overall trend of winter > spring > autumn > summer. The content of nitrate (NO₃⁻) and sulfate (SO₄²⁻) ions in the atmosphere were higher in winter, which, together with ammonium, constitute the main components of water-soluble ions in PM_2.5 in Xinxiang City. Source analysis reported that mobile pollution sources (coal combustion emissions, automobile exhaust emissions, and industrial emissions) in Xinxiang City during the winter season contributed more to atmospheric pollution as compared to fixed sources. The results of the risk assessment showed that the non-carcinogenic health risk of heavy metals in fine particulate matter is acceptable to the human body, while among the carcinogenic elements, the order of lifetime carcinogenic risk is arsenic (As) > chromium(Cr) > cadmium (Cd) > cobalt(Co) > nickel (Ni). During periods of haze pollution, the exposure concentration of PM_2.5 has a certain lag effect on blood routine parameters. On the day when haze pollution occurs, when the daily average concentration of PM_2.5 rises by 10 μg·m⁻³, hemoglobin (HGB) and platelet count (PLT) increase, respectively, by 9.923% (95% CI, 8.741–11.264) and 0.068% (95% CI, 0.067–0.069). GAM model analysis predicted the maximum effect of PM_2.5 exposure concentration on red blood cell count (RBC) and PLT was reached when the hysteresis accumulates for 1d (Lag0). The maximum effect of exposure concentration ofPM_2.5 on MONO is reached when the lag accumulation is 3d (Lag2). When the hysteresis accumulates for 6d (Lag5), the exposure concentration of PM_2.5 has the greatest effect on HGB. The maximum cumulative effect of PM_2.5 on neutrophil count (NEUT) and lymphocyte (LMY) was strongest when the lag was 2d (Lag1). During periods of moderate to severe pollution, the concentration of water-soluble ions and heavy metal elements in PM_2.5 increases significantly and has a significant correlation with some blood routine indicators.

Soil quality is directly affected by alterations in its microbiological, biological, biochemical, physical, and chemical aspects. The microbiological activities of soil can affect soil fertility and plant growth because it can speed up the cycling of nutrients, enzymes, and hormones that are needed by plants for proper growth and development. The use of different agricultural management practices can influence microbial biomass and enzyme activities by altering soil microclimate, soil microorganism habitat, and nutrient cycling. Based on this, the present work planned to evaluate the impact of conventional, low-input, and organic farming systems in a vegetable field growing celery on microbial biomass and different soil enzyme activities. The present study showed a comparison of the effect of different practices on biological soil quality indicators during two sampling times, i.e., one month after colonization and one month before harvesting. It was observed that the soil microbial biomass in the organic farming system was significantly higher than that found in conventional and low-input practices. Under an organic farming system, the soil microbial biomass in December was significantly higher than that in October. The soil microbial biomass carbon in the 0–20 cm soil layer showed higher variation compared to that in the 20–40 cm layer for all the three of the farming management practices that were used in the study. Additionally, the soil total carbon and total organic carbon were recorded as being higher in the December samples than they were in the October samples. Under all the three of the management practices that were applied, the soil catalase activity was higher in the October samples than it was in the December soil samples that were collected the from 20–40 cm soil layer compared to those that were taken from the 0–20 cm layer. The application of organic fertilizer (chicken and cowmanure compost) resulted inincreases in the soil urease and in the protease activity. The protease activity of the soil samples that were extracted from the 0–20 cm and 20–40 cm soil layers in October was higher in the samples that were taken from farms using conventional practices than it was in the samples that were taken from farms using organic and low-input practices, while the samples that were collected during December from both of the soil layers showed higher protease activity when organic methods had been used. No significant variation in the soil urease activity was observed between the two soil layer samples. Urease activity was the highest when organic management practices were being used, followed by the low-input and the conventional modes. For the conventional and low-input practices, the soil urease activity showed an obvious trend of change that was related to thetime of sampling, i.e., activity in December was significantly higher than activity in October. The novelty of this study was to determine the microbial biomass carbon and enzymatic activity in a six-field crop rotation (tomato, cucumber, celery, fennel, cauliflower, and eggplant) using three management practices: low-input, conventional, and organic systems. The present study showed that the long-term application of organic fertilizers plays a large role in maintaining excellent microbial and enzyme activitythat result in improved soil quality.