Heavy metal pollution in a black shale post-mining site of southern China: Pollution pattern, source apportionment and health risk assessment

Urinary concentrations of heavy metals in pregnant women living near a petrochemical area according to the industrial activity

BACKGROUND

The progressive industrialization has resulted in an increase in heavy metal pollution in the environment, which has a dangerous impact on human health. Prenatal exposure to heavy metals, even at very low concentrations, may be especially harmful to pregnant women and their children. Different industrial activities can contribute to heavy metal pollution in a specific area.

OBJECTIVE

1) To explore the concentrations of heavy metals in urine samples of pregnant women, and 2) to evaluate the potential effect of different industrial activities in Tarragona (Spain).

METHODS

Urinary levels of four heavy metals (nickel (Ni), cadmium (Cd), mercury (Hg), and lead (Pb)) from 368 pregnant women recruited in the ECLIPSES study were analyzed. Home addresses and all the industries potentially releasing heavy metals were geo-referenced. Buffer zones were established within a 1.5, 3, and 5 km radius at the center of each industry. Subsequently, the number of participants living in and out of each buffer zone was recorded.

RESULTS

Urinary levels of Ni and Cd, but not those of Hg and Pb, were obviously increased in pregnant women living near most of the industrial sites. After adjustment for potential co-variates, only Cd showed notable differences according to the industrial activity. Compared to women living outside the buffer, Cd levels were increased in those living within 1.5 and 3 km of chemical industries, within 5 km of energy industries, within 1.5, 3, and 5 km of mineral industries, and within 3 and 5 km of metal processing industries.

CONCLUSION

Among the analyzed heavy metals, Cd showed an increasing trend in urinary concentrations in women living near chemical, energy, mineral, and metal processing industries. This study highlights the need to develop legislative measures to minimize Cd exposure, especially by sensitive populations. Moreover, additive or synergistic effects of co-exposure to other air pollutants should not be disregarded.

Effects of microplastics on the phytoremediation of Cd, Pb, and Zn contaminated soils by Solanum photeinocarpum and Lantana camara

Microplastics are emerging pollutants and have become a global environmental issue. The impacts of microplastics on the phytoremediation of heavy metal-contaminated soils are unclear. A pot experiment was conducted to investigate the effects of four additions (0, 0.1%, 0.5%, and 1% w·w-1) of polyethylene (PE) and cadmium (Cd), lead (Pb), and zinc (Zn) contaminated soil on the growth and heavy metal accumulation of two hyperaccumulators (Solanum photeinocarpum and Lantana camara). PE significantly decreased the pH and activities of dehydrogenase and phosphatase in soil, while it increased the bioavailability of Cd and Pb in soil. Peroxidase (POD), catalase (CAT), and malondialdehyde (MDA) activity in the plant leaves were all considerably increased by PE. PE had no discernible impact on plant height, but it did significantly impede root growth. PE affected the morphological contents of heavy metals in soils and plants, while it did not alter their proportions. PE increased the content of heavy metals in the shoots and roots of the two plants by 8.01-38.32% and 12.24-46.28%, respectively. However, PE significantly reduced the Cd extraction amount in plant shoots, while it significantly increased the Zn extraction amount in the plant roots of S. photeinocarpum. For L. camara, a lower addition (0.1%) of PE inhibited the extraction amount of Pb and Zn in the plant shoots, but a higher addition (0.5% and 1%) of PE stimulated the Pb extraction amount in the plant roots and the Zn extraction amount in the plant shoots. Our results indicated that PE microplastics have negative effects on the soil environment, plant growth, and the phytoremediation efficiency of Cd and Pb. These findings contribute to a better knowledge of the interaction effects of microplastics and heavy metal-contaminated soils.

Iron-rich red mud and iron oxide-modified biochars: A comparative study on the removal of Cd(II) and influence of natural aging processes

Red mud (RM) is a byproduct of various processes in the aluminum industry and has recently been utilized for synthesizing RM-modified biochar (RM/BC), which has attracted significant attention in terms of waste reutilization and cleaner production. However, there is a lack of comprehensive and comparative studies on RM/BC and the conventional iron-salt-modified biochar (Fe/BC). In this study, RM/BC and Fe/BC were synthesized and characterized, and the influence on environmental behaviors of these functional materials with natural soil aging treatment was analyzed. After aging, the adsorption capacity of Fe/BC and RM/BC for Cd(II) decreased by 20.76% and 18.03%, respectively. The batch adsorption experiments revealed that the main removal mechanisms of Fe/BC and RM/BC are co-precipitation, chemical reduction, surface complexation, ion exchange, and electrostatic attraction, etc. Furthermore, practical viability of RM/BC and Fe/BC was evaluated through leaching and regenerative experiments. These results can not only be used to evaluate the practicality of the BC fabricated from industrial byproducts but can also reveal the environmental behavior of these functional materials in practical applications.