Huanhuan Yang

A new indicator to evaluate the pollution of iron and manganese

Heavy metals in Anshan tailings is in line with Chinese national standards, but it still contains a huge amount of iron and manganese, much higher than the soil background level in China. Iron and manganese leaching into water via precipitation can cause water pollution. The serious acid rain in Liaoning Province exacerbates the process of migration and transformation. Based on the rainfall characteristics of Liaoning Province, the study simulated the leaching process of acid rain to explore the release effect of iron and manganese with different pH values. We studied the behavior of Danio rerio to evaluate the contamination of iron and manganese, finally to obtain an online monitoring method for heavy metal pollution in water. SOD and GPX were measured to explore the toxicity mechanism of iron and manganese. Activated sludge, as a kind of cheap, efficient and recyclable material, has a great effect on removing heavy metals in water. This study is the first to use activated sludge to remove iron and manganese in water, proving that the activated sludge has a significant effect on removal of iron and manganese.

Is sodium percarbonate a good choice in situ remediation of deltamethrin pollution

In this research, the toxic effects of deltamethrin (DM) on the behavior responses of Zebra fish (Danio rerio) in the characteristic of behavior strength were investigated followed by an assessment of an in situ remediation of the DMpollution using sodium percarbonate. Behavior strength of Danio rerio was approximately 0.83 in the control group and was slightly higher than 0.83 in the sublethal treatment (0.1 TU (toxic unit)), which suggested that sublethal DMexposure could induce a stimulation effect in 48 h of exposure. In lower DM concentration treatments (0.5 and 1.0 TU), behavior strength could be inhibited significantly. Behavior responses of Danio rerio showed a gradually increased tendency when they were exposed to higher concentration of DM, and the declining amplitudes of behavior strength changed with the increase of DMconcentrations. These results suggested that DM had evident acute toxicity effects on the behavior responses of Danio rerio with a good dose-effect relationship. The in situ remediation of the DM pollution using sodium percarbonate showed that the toxic effect of DM on behavior responses of Danio rerio could be eliminated even in the highest concentration of DM (5.0 TU). Meanwhile, the behavior response of Danio rerio in the treatment of sodium percarbonate was the same as in the control, which indicated that sodium percarbonate had no evident toxic effects on the behavior of Danio rerio in the current concentration. This study suggested that adding sodium percarbonate in situ might be a good way to eliminate the DM toxic effects.

The toxic effects of deltamethrin on Danio rerio: the correlation among behavior response, physiological damage and AChE

Pyrethroid pesticides constitute one of the main types of pesticides in the domestic market. Deltamethrin, one of the typically used pyrethroid pesticides, has high insecticidal activity, and a wide insecticidal spectrum, and is widely used in agricultural production and other activities. A previous study showed deltamethrin to have obvious toxic effects on zooplankton, fish and other aquatic organisms. In the current work, we used fish of the model organism Danio rerio to comprehensively evaluate the effects of deltamethrin on their behavior, physiology and acetylcholinesterase (AChE) activity. During the initial reaction of the fish to the presence of deltamethrin, their behaviors were found to change with the drug concentration, which directly showed the toxic effect of this pesticide on the fish. The AChE activity of the fish showed a response similar to that of their behavior. Moreover, deltamethrin caused significant damage to their gills and liver. However, being major organs of Danio rerio, the gills and liver showed a different response pattern than did the behavior of the fish.

Biochemical mechanism of phytoremediation process of lead and cadmium pollution with Mucor circinelloides and Trichoderma asperellum

This study focused on the bioremediation mechanisms of lead (0, 100, 500, 1000 mg kg-1) and cadmium (0,10,50,100 mg kg-1) contaminated soil using two indigenous fungi selected from mine tailings as the phytostimulation of Arabidopsis thaliana. The two fungal strains were characterized as Mucor circinelloides (MC) and Trichoderma asperellum (TA) by internal transcribed spacer sequencing at the genetic levels. Our research revealed that Cadmium was more toxic to plant growth than lead and meanwhile, MC and TA can strengthen A. thaliana tolerance to cadmium and lead with 40.19-117.50% higher root length and 58.31-154.14% shoot fresh weight of plant compared to non-inoculation. In this study, TA exhibited a higher potential to the inactivation of cadmium; however, MC was more effective in lead passivation. There was a direct correlation between the type of fungi, heavy metal content, heavy metal type and oxidative damage in plant. Both lead and cadmium induced oxidative damage as indicated by increased superoxide dismutase and catalase activities, while the antioxidant levels were significantly higher in fungal inoculated plants compared with those non-inoculated. The analysis of soil enzyme activity and taxonomic richness uncovered that the dominant structures of soil microbial community were altered by exogenous microbial agents. MC enhanced higher microbial diversity and soil enzyme activity than TA. The two indigenous fungi lessened several limiting factors with respect to phytoremediation technology, such as soil chemistry, contamination level and transformation, and metal solubility.

Migration and speciation of heavy metal in salinized mine tailings affected by iron mining

The negative effects of heavy metals have aroused much attention due to their high toxicity to human beings. Migration and transformation trend of heavy metals have a close relationship with soil safety. Researching on migration and transformation of heavy metals in tailings can provide a reliable basis for pollution management and ecosystem restoration. Heavy metal speciation plays an important role in risk assessment. We chose Anshan tailings for our study, including field investigations and laboratory research. Four typical heavy metal elements of mine tailings {Fe (373.89 g/kg), Mn (2,303.80 mg/kg), Pb (40.99 mg/kg) and Cr (199.92 mg/kg)} were studied via Tessier test in vertical and horizontal direction. The main speciation of heavy metals in Anshan tailings was the residual. However, heavy metals have a strong ability for migration and transformation in vertical and horizontal directions. Its tendency to change from stable to unstable speciation results in increasing bioavailability and potential bioavailability. Fe, Mn, Pb and Cr showed different ability in the migration and transformation process (Mn > Pb > Fe > Cr) depending on the characteristics of heavy metals and physicochemical properties of the environment.

Physiological responses of Suaeda glauca and Arabidopsis thaliana in phytoremediation of heavy metals

The over discharge of mine tailing cause consequent heavy metal pollution. Phytoremediation as one of the most viable and efficient method for this problem has aroused much attention. In this research, the growth and physiological responses of Suaeda glauca and Arabidopsis thaliana plants were investigated, and the soil conditions (pH and enzyme activity) were evaluated further under varied levels of cadmium (Cd), lead (Pb) and manganese (Mn). The results showed that heavy metals could inhibit the growth of plants. The fresh weight and photosynthetic pigments contents of Suaeda and Arabidopsis decreased with the increased concentration of Cd, Pb and Mn. As a monitoring plant, growth status of Arabidopsis showed good dose-effect when treated by heavy metals. S. glauca showed better tolerance capacity for Cd, Pb and Mn, when compared with Arabidopsis. Moreover, the physical and chemical properties of soil were significantly improved after phytoremediation. The soil catalase activity decreased with increased concentration of metal treatments, which showed similar regularity with microbial community. Changes of microbial community could not only indicate the soil environment but also suggest that S. glauca plants had better influences on the soil microbial environment. The introduction of plants resulted in a 0.5-0.8 units change in soil pH compared with the initial pH level. The present study provided the potential of S. glauca plants for phytoremediation in contaminated soil. Microbial community of Suaeda and Arabidopsis were evaluated and showed different regularity because of the rhizosphere effect. Soil microorganisms played an important role in the process of bioremediation. Meantime the main problems about physical and chemical properties of mine tailings were improved. It could be of great significance to the large-scale resource utilization and economical remediation of mine tailings.

An extraction-assay system: Evaluation on flavonols in plant resistance to Pb and Cd by supercritical extraction-gas chromatography

In this research, supercritical carbon dioxide extraction (SFE) showed better extraction effect when compared with Solid- liquid extraction (SLE), Soxhlet extraction (SE) and Ultrasonic extraction (UE), not only in the rate but also the time. The comparison among these three extraction modifiers, including acetone, ethanol and methanol demonstrated that ethanol was preferred to SFE due to its high extraction effect and low toxicology. In addition, parameter of SFE, influence of temperature and pressure were investigated, and the best extraction effect was achieved at the optima conditions, temperature of 40°C and the pressure of 35 MPa. Thus, SFE is a highly effective method for flavonols extraction, requiring minimum energy and producing non-toxic byproduct. SFE-GC system is applied for the evaluation on flavonols that plays a key role in plant resistance to heavy metal, with its content and synthetase gene expression significantly increasing in plant when threatened by heavy metal. Besides, results indicated that flavonols can improve plant resistance to oxidative stress by quenching the redundant ROS in matrix.

Soil sustainable utilization technology: mechanism of flavonols in resistance process of heavy metal

The soil ecosystem is critical for agricultural production, affecting many aspects of human health. Soil has more unknown biodiversity and edaphic parameters than any other ecosystem especially when polluted. Metagenomics and metatranscriptomics were applied to research on toxicological characteristics of Pb and resistance mechanism of flavonols. Rhizosphere microorganisms–plants system, a unified system closely related to soil environment was taken as research object. Results emphasize gene expression changes in different test groups. Gene ontology enrichment and eggNOG showed that Pb has a toxic effect on gene and protein function which concentrated on ATPase and ATP-dependent activity. Differentially expressed genes in the flavonols group indicated that flavonols regulate amino acid transport and other transportation process related to Pb stress. Kegg analysis represents that Pb interferences energy production process via not only the upstream like glycolysis and tricarboxylic acid (TCA) circle but also oxidative phosphorylation process, which can also produce reactive oxygen species and impact the eliminating process. Flavonols have shown the ability in alleviating toxic effect of Pb and improving the resistance of plants. Flavonols can recover the electronic transmission and other process in TCA and oxidative phosphorylation via ascorbic acid-glutathione metabolism. Flavonols activated antioxidative process and non-specific immunity via vitamins B2–B6 metabolism.