Potentially Toxic Elements’ Contamination of Soils Affected by Mining Activities in the Portuguese Sector of the Iberian Pyrite Belt and Optional Remediation Actions: A Review

Both sectors of the Iberian Pyrite Belt, Portuguese and Spanish, have been exploited since ancient times, but more intensively during and after the second half of the 19th century. Large volumes of polymetallic sulfide ore were extracted in open pits or in underground works, processed without environmental concerns, and the generated waste rocks and tailings were simply deposited in the area. Many of these mining sites were abandoned for years under the action of erosive agents, leading to the spread of trace elements and the contamination of soils, waters and sediments. Some of these mine sites have been submitted to rehabilitation actions, mostly using constructive techniques to dig and contain the contaminated tailings and other waste materials, but the remaining soil still needs to be treated with the best available techniques to recover its ecosystem functions. Besides the degraded physical structure and poor nutritional status of these soils, they have common characteristics, as a consequence of the pyrite oxidation and acid drainage produced, such as a high concentration of trace elements and low pH, which must be considered in the remediation plans. This manuscript aims to review the results from studies which have already covered these topics in the Iberian Pyrite Belt, especially in its Portuguese sector, considering: (i) soils’ physicochemical characteristics; (ii) potentially toxic trace elements’ concentration; and (iii) sustainable remediation technologies to cope with this type of soil contamination. Phytostabilization, after the amelioration of the soil’s properties with organic and inorganic amendments, was investigated at the lab and field scale by several authors, and their results were also considered.

Mapping Bauxite Mining Residues Using Remote Sensing Techniques

Bauxite residuals from abandoned mining sites are both an environmental challenge and a possible source of secondary raw materials. Processing of multispectral and hyperspectral images with the best available techniques can help to produce multiscale spatial maps of elements inside and around the mining sites. The authors propose a procedure for mapping elements concentration using multiple data sets at different scales and resolutions. A comparison between multispectral Sentinel-2 images and hyperspectral PRISMA processing is performed over some case studies of bauxite residues in the Mediterranean area. Specifically, a case study from Italy is composed regarding artificial canyons created by past artisanal mining activities and by stockpiles of extracted bauxite. Hyperspectral punctual measurements (spectroradiometer surveys) were taken in various zones of the bauxite site, where infield topsoil samples were also taken for X-ray fluorescence chemical analysis. Final concentration maps were estimated by performing geostatistical techniques.

Lab Scale Model Experiment of Smart Hopper System to Remove Blockages Using Machine Vision and Collaborative Robot

In this study, we propose a smart hopper system that automatically unblocks obstructions caused by rocks dropped into hoppers at mining sites. The proposed system captures RGB (red green blue) and D (depth) images of the upper surfaces of hopper models using an RGB-D camera and transmits them to a computer. Then, a virtual hopper system is used to identify rocks via machine vision-based image processing techniques, and an appropriate motion is simulated in a robot arm. Based on the simulation, the robot arm moves to the location of the rock in the real world and removes it from the actual hopper. The recognition accuracy of the proposed model is evaluated in terms of the quantity and location of rocks. The results confirm that rocks are accurately recognized at all positions in the hopper by the proposed system.

Soil Carbon Sequestration in Novel Ecosystems at Post-Mine Sites—A New Insight into the Determination of Key Factors in the Restoration of Terrestrial Ecosystems

Mining activities are one of the main causes of land degradation around the world and reduce the quality of the surrounding ecosystems. Restoration approaches using different vegetations and reclamation methods have been implemented to address this issue. In this review, paper, different studies focusing on the effect of the restoration of mining sites on the accumulation of soil organic carbon (SOC) were analyzed. SOC in reclaimed mining soil (RMS) increased considerably after various restoration efforts were implemented. The amount of SOC accumulated in RMS was mostly influenced by the restoration age, vegetation type, and substrate or type of reclamation used. From the scientific papers analyzed, we found that SOC accumulation increases with restoration age; however, vegetation type and reclamation have varied effects. According to the review, the restoration of mine sites with vegetation resulted in a rate of SOC accumulation ranging from 0.37 to 5.68 Mg SOC ha−1 year−1. Climate conditions influenced the type of vegetation used for restoration. Regrading, liming, NPK fertilization, and seeding a mix of legumes and grasses were the most efficient reclamation techniques. Additionally, the use of grass and legume better facilitates the early accumulation of SOC compared with afforestation. Thus, the selection of appropriate tree species composition, reclamation treatments, and restoration age are the key factors for a high SOC accumulation rate.

Public Control of Radiation Hazardous Facilities: Experience and Results

Independent public control of nuclear facilities is aimed at raising awareness of the general public about the effectiveness of measures to protect the environment from the radiation effects. The experience and the result of interaction between specialists of the Academy of Sciences and a higher school in organizing and conducting public control by instrumental methods of the territories for the location of radiation-hazardous facilities: uranium mining sites by underground leaching, the area of the Belarusian nuclear power plant in the pre-operational period, the area of the floating nuclear power plant "Akademik Lomonosov" and the publicly accessible territory of control area of the Mayak Production Association. Such a pooling of efforts allows for the formation of new ways of obtaining reliable information for any interested public. The results of special studies characterizing the radioecological situation in the surveyed territories are presented.

Impact of Nanotechnology on Environment – A Review

The world is facing significant environmental challenges like improving the standard of air, soil, and water. Currently, industry is that specialize in detecting pollutants (from chemical spills, fertilizer and pesticide run-off), improving industrial and mining sites, treating contaminants and stopping further pollution. A potential solution to those problems is to use nanomaterials. Nanomaterials are often wont to assist with cleaning the environment and even provide efficient energy solutions, like nanomaterial based solar cells additionally to the present, nanomaterials help to enhance the standard and performance of the many consumer products. As results of this, the exposure to made nanomaterials is increasing day-by-day. However, there are both positive and negative impacts on the environment thanks to nanotechnology.Recent advances in nanotechnology have shown numerous societal benefits through the event or improvement of smart materials. Several engineered nanomaterials (ENMs) are produced during the last years which will be found in related sectors like health, food, home, automotive, electronics, and computers (Hansen et al., 2016). The estimated output of ENMs produced was up to 270,000 metric tons/year and during this case considering only SiO2, TiO2, FeOx, AlOx, ZnO, and CeO2 nanoparticles.

Teresterial Background Ionizing Radiation around Lead/Zinc Mining Site in Ishiagu, Ebonyi State, Nigeria

Background ionizing radiation around Lead/Zinc mining sites at Ishiagu, Ebonyi State was carried out using appropriate equipment. The background ionizing radiation of the environment was determined by measuring the radiation exposure rates using Radalert-200 and Geographical Positioning System (GPS). Radiological health parameters and effective dose to different organs of the body was estimated. The average exposure rate of 0.00017mSv/h (0.017mR/h) measured was relatively higher than the world acceptable value of 0.00013mSv/h (0.013mR/h ). All the radiological risk parameters estimated are relatively high. The result of this work shows that the mining µactivities have enhanced the radiation level of Ishiagu and health status of the populace.

Assessment of Activity Concentration of Radionuclides in Soil and Cassava Food Crop from Solid Mineral Mining Site in Ishiagu, Ivo L.G.A of Ebonyi State, Nigeria

The assessment of activity of concentration of radionuclides in soil and food crops from solid mineral mining sites at Ishiagu, in Ivo L.G.A of Ebonyi State was carried out using the necessary measuring instruments. Samples of soil and cassava crop collected from around the mining sites. The samples were analysed using gamma ray spectrometry. The average activity concentration of 226Ra, 232Th and 40K in soil samples were 12.37,16.08, and 144.29 Bqkg-1 while those for cassava were 2.81, 16.80, and 205.41 Bqkg-1. The soil/plant radionuclide transfer ratio estimated are 0.62, 2.43 and 2.51 for 226Ra, 232Th and 40K, respectively. All the radiological risk parameters estimated are relatively low. The result of this work showed that the obtained results for all samples were lower than the international accepted limit. Hence, from radiological health standpoint, the obtained values of effective doses may not pose significant threat to both human and the environment.

Genome and Transcriptome Sequencing of Novel Pseudomonas sp. NLX-4 Strain Involved in Bio-Restoration of Over Exploited Mining Sites

Microbial weathering processes can significantly promote soil properties and enhance rock to soil ratio. Some soil-inhabiting bacteria exhibit efficient rock-dissolution abilities by releasing organic acids and other chemical elements from the silicate rocks. However, our understanding of the molecular mechanisms involved during bacterial rock-dissolution is still limited. In this study, we performed silicate rock-dissolution experiments on a novel Pseudomonas sp. NLX-4 strain isolated from an over-exploited mining site. The results revealed that Pseudomonas sp. NLX-4 strain efficiently accelerates the dissolution of silicate rocks by secreting amino acids, exopolysaccharides, and organic acids. Through employing genome and transcriptome sequencing (RNA-seq), we identified the major regulatory genes. Specifically, fifteen differentially expressed genes (DEGs) encoding for siderophore transport, EPS and amino acids synthesis, organic acids metabolism, and bacterial resistance to adverse environmental conditions were highly up-regulated in silicate rock cultures of NLX-4 strain. Our study proposes a novel bacterial based approach for improving the ecological restoration of over-exploited rock mining-sites.

Radiation dose risk variability and its implication in industrial and mining regions, NW Nigeria

The study area located in the southern part of Kebbi State, northwestern Nigeria, has witnessed intense mining activities and upscale industrialization in recent years. These events have necessitated deeper and insightful studies into radiological hazard evaluation to mitigate associated adverse consequences and enforce protective measures in the environment. A total of 45 sampled locations each were taken for both industrial and mining sites in northwestern Nigeria to determine the concentration of Potassium-40, Thorium-232 and Uranium-238 radionuclides as applied to radiological hazard analysis. The mean value of the absorbed dose in the industrial site was 90 nGy/h, whereas the mining site recorded a mean value of 210 nGy/h. Other radiological indices such as radium equivalent factor, external risk assessment, internal index and representative gamma index recorded mean values of 187.68, 0.507, 0.547 and 0.768 respectively, whereas the same hazard indices presented higher values of 412.58, 1.114, 1.231 and 1.675 respectively in the mining site. The variability studies showed that the dose risk ratio of the industrial region to the mining region is 1:2. The mining site presented radiological hazard indices higher than the recommended global threshold hence should be classified as a restricted zone to forestall health-related crises which may manifest among local dwellers.