Environmental risk assessment of lead-zinc mining: a case study of Adudu metallogenic province, middle Benue Trough, Nigeria

CaAl-Layered Double Hydroxides-Modified Biochar Composites Mitigate the Toxic Effects of Cu and Pb in Soil on Pea Seedlings

Compound contamination of soil with heavy metals copper (Cu) and lead (Pb) triggered by mining development has become a serious problem. To solve this problem, in this paper, corncob kernel, which is widely available and inexpensive, was used as the raw material of biochar and modified by loading CaAl-layered double hydroxides to synthesize biochar-loaded CaAl-layered double hydroxide composites (CaAl-LDH/BC). After soil remediation experiments, either BC or CaAl-LDH/BC can increase soil pH, and the available phosphorus content and available potassium content in soil. Compared with BC, CaAl-LDH/BC significantly reduced the available content of Cu and Pb in the active state (diethylenetriaminepentaacetic acid extractable state) in the soil, and the passivation rate of Cu and Pb by a 2% dosage of CaAl-LDH/BC reached 47.85% and 37.9%, respectively. CaAl-LDH/BC can significantly enhance the relative abundance of beneficial microorganisms such as Actinobacteriota, Gemmatimonadota, and Luteimonas in the soil, which can help to enhance the tolerance and reduce the enrichment ability of plants to heavy metals. In addition, it was demonstrated by pea seedling (Pisum sativum L.) growing experiments that CaAl-LDH/BC increased plant fresh weight, root length, plant height, catalase (CAT) activity, and protein content, which promoted the growth of the plant. Compared with BC, CaAl-LDH/BC significantly reduced the Cu and Pb contents in pea seedlings, in which the Cu and Pb contents in pea seedlings were reduced from 31.97 mg/kg and 74.40 mg/kg to 2.92 mg/kg and 6.67 mg/kg, respectively, after a 2% dosage of CaAl-LDH/BC, which was a reduction of 90.84% and 91.03%, respectively. In conclusion, compared with BC, CaAl-LDH/BC improved soil fertility and thus the plant growth environment, and also more effectively reduced the mobility of heavy metals Cu and Pb in the soil to reduce the enrichment of Cu and Pb by plants.

Potential Ecological Risk and Human Health Risk Assessment of Heavy Metal Pollution in Industrial Affected Soils by Coal Mining and Metallurgy in Ostrava, Czech Republic

The heavy metal pollution of soils has become serious environmental problem, mainly in localities with high industrialization and rapid growth. The purpose of this detailed research was to determine the actual status of heavy metal pollution of soils and an assessment of heavy metal pollution in a highly industrialized city, Ostrava, with a history of long-term impacts from the metallurgy industry and mining. The ecological risks to the area was subsequently also assessed. The heavy metals Cd, Hg, Cu, Mn, Pb, V, Zn, Cr and Fe were determined in top-soils (0–20 cm) using atomic absorption spectrometry (F AAS, GF AAS) from three areas with different anthropogenic loads. The obtained data expressed as mean metal concentrations were very varied among the sampled soils and values of all analyzed metal concentrations were higher than its background levels. To identify the ecological risk and assessment of soil pollution, various pollution indices were calculated, such as single pollution indices (I_geo, CF, EF, PI) and total complex indices (IPI, PLI, PI_Nemerow, C_deg, mC_deg, E_r and PERI). The identification of pollution sources was assessed using Pearson’s correlation analysis and multivariate methods (HCA, PCA/FA). The obtained results confirmed three major groups of metals (Fe–Cr, Pb–Cu and Mn–V). A human health risk was identified in the case of Pb, Cd and Cr, and the HI value of V for children also exceeded 1.

Seasonal quality variation and environmental risks associated with the consumption of surface water: implication from the Landzun Stream, Bida Nigeria

Water constitutes a major environmental and public health concerns worldwide. A large proportion of global water consumption is sourced from surface water. The dependency level on surface water is higher in developing countries, especially in rural-to-semi-urban areas, where subsurface water is not accessible. Presented in this paper is a spatiotemporal and hydrochemical quality assessment of the spring-originated Landzun Stream in Bida, Nigeria; which is usually consumed in its untreated state. Water samples were systematically collected in eighteen locations along the stream channel in both rainy and dry seasons at an equidistance interval of 500m. On-site and laboratory measurement of important physical and hydrochemical parameters were carried out using standard procedures. Water temperature in the rainy season (34–37 °C) slightly exceeds measured values in the dry season (29–33 °C). 72.22% (rainy) and 83.33% (dry) of collected samples did not meet the odourless requirement for drinking water. Similarly, estimated percentages of 66.67 and 94.44 of collected samples in rainy and dry seasons respectively have a taste. Contrary to data in the rainy season, 89%, 11%, 67% and 56% of the dry season's samples were enriched in magnesium (Mg), lead (Pb), potassium (K) and iron (Fe) respectively above the 2018 World Health Organisation guidelines for drinking water. This study further established that seasonal variation plays a major role in altering the aesthetic surface water quality. The intake of untreated surface water is a vehicle for potential water-borne diseases and allergies, hence alternative sources of drinking water for the populace dependent on the Landzun Stream is recommended to reduce risks and possible dangers of consuming the stream water.

A newly discovered Cd-hyperaccumulator Lantana camara L

The identification of hyperaccumulators is a key step for the phytoextraction of contaminated soils. However, few cadmium (Cd) hyperaccumulators have been identified in the plant kingdom. In our previous field investigations, Lantana camara L. plants exhibited some traits of hyperaccumulators. To confirm whether this species is a Cd hyperaccumulator, laboratory dose-gradient experiments and field sample analysis experiments were first designed and implemented in an integrated manner. The results showed that lantana plants did not exhibit any visible damage or marked reduction in shoot biomass when grown in Cd-contaminated soil with less than 100 mg kg^-1 Cd. Moreover, the lantana plants exhibited high Cd tolerance with effective coordination of photosynthesis and rapid reactive oxygen species scavenging. Most importantly, the bioaccumulation factors (BFs) and translocation factors (TFs) were greater than 1.0 in all the Cd treatments, while the Cd concentrations in the shoots were all greater than those in the roots and were also greater than 100 mg kg^-1, the threshold value for a Cd hyperaccumulator. Our data provide comprehensive evidence that lantana plants have the typical characteristics of a Cd hyperaccumulator and thus can be regarded as potential Cd-hyperaccumulating plants for the restoration of Cd-polluted soils.

Temperature-driven variation in the removal of heavy metals from contaminated tailings leaching in northern Norway

High amounts of tailings with a low recycling rate are generated during mining and smelting processes, and a lot of environmental problems were caused by heavy metal leaching from tailings. Temperature is a key point in heavy metals leaching, and knowing the effects of temperature on tailings leaching is useful for tailings management. A small-scale batch leaching experiment was conducted at different temperatures to test temperature-driven heavy metal leaching from tailings in the arctic area. The variation in the leaching of heavy metals from tailings was investigated by a small-scale batch leaching experiment. Results showed that 10 °C is a threshold temperature for the leaching activity of the tested elements. Fe, Cr, and Cu are significantly correlated with temperature in the leaching. Leaching rates of Cr, Cu, and Ni increase as temperature rises. Leaching rates of Cr, Cu, Ni, V, and Zn change by a polynomial model with temperatures, whereas that of Fe changes with a linear model. V shows an antagonistic relationship with Cu, Fe, and Ni in the leaching. However, Cu, Cr, Ni, and Fe show a synergistic relationship. Discovering the threshold temperature of leaching tailings in the arctic area and concluding the influence factors and the relationship between heavy metals leaching and temperature are useful for tailings management.