Mechanism analysis of heavy metal lead captured by natural-aged microplastics.

In this paper, the mechanism of lead (Pb(II)) captured by natural-aged microplastics in aqueous medium was explored. Compared with pristine microplastics, the natural-aged microplastics were more efficient for adsorbing Pb(II). After treated by hydrochloric acid (HCl) or sodium hydroxide (NaOH), the organic film was damaged and the adsorption efficiency decreased obviously, which proved that the organic film played an important role in Pb(II) capture. The fitting results of the isothermal adsorption model showed that this adsorption process was more in line with Langmuir model than with Freundlich model, and the maximum adsorption amount (13.60 mg/g) could also be obtained from the Langmuir model. Based on the comprehensive analysis of XRD, XPS and FTIR results, it was found that Pb(II) capture by natural-aged microplastics was mainly determined by the oxygen containing functional groups (carboxyl and hydroxyl groups) on the organic film. Besides, the measurement results of Zeta potential and pH effect showed that electrostatic interaction was mainly responsible for the Pb(II) capture process.

A review: Research progress on microplastic pollutants in aquatic environments.

The ubiquitous problems of microplastics in waters are receiving global attention as microplastics can harm aquatic organisms, and finally can accumulate in the human body through biological chain amplification. In addition, microplastics act as a carrier capable of carrying heavy metals, organics, which form complex pollutants. These new combinations of pollutants, once ingested by aquatic organisms, are amplified through the food chain and can have unpredictable ramifications for aquatic organisms and human beings. Therefore, human beings are not only the source of plastic pollution, but also the sink of microplastic pollution. Therefore, this study reviews the source and distribution of microplastics, and their combined ability with heavy metals, antibiotics, and persistent organic pollutants in aquatic environments. Furthermore, it describes the interaction between aquatic organisms and microplastics. Finally, some suggestions are put forward to promote the sustainable application of microplastics. This work provides theoretical guidance for combining microplastics with other pollutants in water, and the accumulation of microplastics in food chain.

Acute Toxicity of Divalent Mercury Ion to Anguilla japonica from Seawater and Freshwater Aquaculture and Its Effects on Tissue Structure.

The acute toxicity of divalent mercury ion to Anguilla japonica from seawater and freshwater aquaculture was assessed. In particular, the effects of toxicity on the microstructures of the gill and liver tissues were examined using the hydrostatic method, without feeding, at a water temperature of 20 °C. The median lethal concentrations (LC50) of divalent mercury ion to fishes in seawater and freshwater over various durations were: 24 h = 1.637 and 1.428 mg/L; 48 h = 1.562 and 1.377 mg/L; 72 h = 1.530 and 1.284 mg/L; and 96 h = 1.442 and 1.228 mg/L. The safety mass concentrations were 0.1442 and 0.01228 mg/L, respectively. After exposure to divalent mercury ion, adhesion between the gill lamellae and massive cellular disintegration and necrotic shedding were observed in the gill tissue sections. The liver tissues underwent hyperemia and swelling, with the appearance of blood spots, swelling of the hepatocyte mitochondria, dilation of the rough endoplasmic reticulum, and intercellular inflation.

Enhancement of Detoxification of Petroleum Hydrocarbons and Heavy Metals in Oil-Contaminated Soil by Using Glycine-ß-Cyclodextrin.

Soil contamination with petroleum hydrocarbons and heavy metals is a widespread environmental problem. In recent years, cyclodextrin has attracted research interest because of its special hole structure that can form inclusion complexes with certain small molecules. However, the solubility of ß-cyclodextrin (ß-CD) in water is low and it crystallizes easily, leading to its low utilization in practice. In this experiment, we connected ß-CD with glycine under alkaline conditions to prepare glycine-ß-cyclodextrin (G-ß-CD), which is water soluble, has stronger coordinating ability with heavy metals, and is more suitable for treating oil-contaminated soil. The results show that G-ß-CD provides better desorption of petroleum hydrocarbons and heavy metals in soils with low organic matter content (1%) and NaNO3 of 0.25 mol/L at 70 g/L G-ß-CD under mildly acidic (pH 5⁻6) conditions. The results indicate that petroleum hydrocarbons and heavy metals were removed simultaneously by means of pretreatment with G-ß-CD, and the results can provide a theoretical basis for remediation of petroleum-contaminated soil.