Pollution characteristics, bioavailability, and risk assessment of heavy metals in urban road dust from Zhengzhou, China.

To analyze contamination levels, spatial distribution characteristics, bioavailability, and risks of heavy metals (Cr, Ni, Cu, Zn, As, Cd, Hg, and Pb), 65 road dust samples were collected and tested by ICP-MS from Zhengzhou in October 2023. The mean concentrations of most heavy metals, except Ni, exceeded their corresponding background values, with the mean concentration of Cd being 7.43 times that of its background. Spatially, for most heavy metals, higher concentrations were concentrated within the central area, and notable pollution hotspots emerged in proximity to construction area. Cr, Ni, Cu, As, and Pb were mostly bound to residual fraction with lower bioavailability, while Cd and Zn were mainly in exchangeable fraction with higher bioavailability. The enrichment factor, geo-accumulation, contamination factor, and pollution load index indicated that Cd and Hg were highly contaminated, particularly Cd, yet the study area remained moderately polluted. The average RI value of 384.66 indicated a considerate ecological risk, and Cd caused the highest potential ecological risk. Both of the non-carcinogenic and carcinogenic risks were insignificant, however, the human health risk of Cr, As, and Pb demand attention. The research results can provide theoretical basis and data support for the pollution prevention and control of urban environment of Zhengzhou.

Bioinspired Artificial Muscles Based on Sodium Alginate-Wrapped Multi-Walled Carbon Nanotubes and Molybdenum Disulfide Composite Electrode Membrane.

Using a naturally extracted polymer sodium alginate extracted from natural seaweed as the primary raw material, we have successfully developed an electroactive actuator known as biomimetic artificial muscle (BMAM). In comparison to conventional synthetic materials, this BMAM aligns more coherently with the prevailing principles of environmentally friendly development. During the preparation of the BMAM electrode membrane, we employed ultrasonic oscillation to adsorb varying quantities of MoS2 onto a reticulated structure formed by multi-walled carbon nanotubes (MWCNTs), thus enhancing the mechanical and electrochemical performance of the BMAM. Scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDS) confirmed the successful encapsulation of MoS2 by the MWCNTs network in the composite. To measure the output force of the BMAM fabricated with different masses of MoS2 doping, we established a self-built experimental platform and conducted tests on the electrode membranes doped with varying quantities of MoS2 using an electrochemical workstation. The results revealed that the BMAM exhibited optimal mechanical performance when doped with 1.5 g of MoS2, with a maximum output force of 7.81 mN, an output force density of 34.36 mN/g, and a response rate of 0.09 mN/s. These performances were improved by 309%, 276%, and 175%, respectively, compared to the samples without MoS2 doping, with a mass-specific capacitance enhancement of 151%.

Analysis of the Impact of Electrochemical Properties of Copper-Doped Electrode Membranes on the Output Force of Biomimetic Artificial Muscles.

In this study, a biomimetic artificial muscle electroactive actuator was fabricated using environmentally friendly sodium alginate extract. Ultrasonic agitation was employed to embed ultrafine copper powder within a mesh-like structure formed by multi-walled carbon nanotubes (MWCNTs), aimed at reducing the internal resistance of the composite electrode membrane and enhancing its output force performance. Focused gallium ion beam-scanning electron microscopy observations, energy-dispersive X-ray spectroscopy (EDS) analysis, and surface morphology imaging confirmed the successful incorporation of the ultrafine copper powder into the MWCNT network. Additionally, we designed and constructed an output force measurement apparatus to assess the output performance of biomimetic artificial muscles (BMAMs) doped with varying quantities of ultrafine copper powder. Electrochemical testing results demonstrated that the artificial muscles exhibited optimal performance when doped with a mass of 1.5 g, yielding a maximum output force of 6.96 mN, an output force density of 30.64 mN/g, and a peak average rate of 0.059 mN/s. These values represented improvements of 224%, 189%, and 222% compared to the electrode membrane without the addition of ultrafine copper powder, respectively.

A Comprehensive Exploration on Occurrence, Distribution and Risk Assessment of Potentially Toxic Elements in the Multi-Media Environment from Zhengzhou, China.

Road dust (RD), roadside soils (RS) and river surface sediments (sediments) are important materials for evaluating contaminant levels in urban areas. This study aims to investigate the contaminant characteristics, pollution levels and ecological risks of RD, RS and sediments of potentially toxic elements (PTEs), including Cr, Ni, Cu, Zn, As, Cd, Hg and Pb, in the central urban area of Zhengzhou. Results reveal that RD shows a higher concentration of PTEs when compared to the other two environments. The spatial distribution characteristics suggest that PTEs in RD, RS and sediments may come from different sources. The geo-accumulation index (Igeo) was used to describe that the RD was moderately to extremely contaminated with Cd and Hg, while both RS and sediments were significantly enriched with Cd and Hg. For RD, RS and sediments, the potential ecological risk (RI) demonstrates a high potential ecological risk from Cd and Hg. Overall, PTEs in Zhengzhou road dust present a moderate risk.