Characterisation of the Dynamics of Leachate Contamination Plumes in the Surrounding of the Hulene - B Waste Dump, Maputo, Mozambique

The contamination of areas around solid urban waste dumps is a global challenge for the maintenance of environmental quality in large urban centres in developing countries. This study applied geophysical methods (electrical resistivity) to identify leachate contamina-tion plumes in the subsoil and groundwater, as well as to describe their temporal (2020 and 2021) dynamics in the lithology and groundwater around the Hulene - B waste dump, Maputo, Mozambique. Geophysical methods (electrical resistivity) were applied to identify possible groundwater contamination plumes, their dynamics, mechanisms of their enrichment and dispersion. Eight 400 m electrical resistivity profiles were performed, four profiles in January 2020 and four profiles in May 2021, overlapped, and the data were inverted with RES2D software. The electrical resistivity models indicate an E - W move-ment of large contamination plumes that dilute superficially into the natural surface wa-ter receiving basin and groundwater, creating zones of resistive anomalies. The thickness of the plumes in the subsurface environment was shown to be extensive in summer for profiles 1a and 2b and we associate it with the higher leachate production and migration mechanisms, which are intense in the hot and rainy season. Profile 4b showed the prop-agation of anomalous surface and subsurface areas, which was associated with higher leachate production and migration process in the new deposition zone (west). The spatial distribution of contamination plumes at both stations reduced significantly as we moved further away from the waste deposit, revealing the attenuating effect of groundwater and lithological substrate (Profile 3 a, b, and fig.7).

Mining Waste Volume Estimation Using Airborne Lidar Data and Historical Maps: A Case Study of Tailing Piles in Szklary, Lower Silesia

Reliable feasibility analysis of potential exploitation of a mining waste deposit poses a great challenge. One of the most crucial parts of this process is the approximation of the deposit volume. In this case study we propose a novel method of tailing pile volume estimation using open remote sensing and cartographic data. For selected piles, the difference between the proposed and classical approach reach 50% of the pile volume, which is a significant change in the potential value of the deposit.

Groundwater chemistry affected by trace elements (As, Mo, Ni, U and V) from a burning alum shale waste deposit, Kvarntorp, Sweden

Worldwide, black shales and shale waste are known to be a potential source of metals to the environment. This project demonstrates ongoing weathering and evaluates leaching processes at a 100-m-high shale waste deposit closed in the 1960s. Some deep parts of the deposit are still burning with temperatures exceeding 500 °C. To demonstrate ongoing weathering and leaching, analyses of groundwater and solid samples of shale and shale waste have been undertaken. Largest impact on groundwater quality was observed downstream the deposit, where elevated temperatures also indicate a direct impact from the burning waste deposit. Groundwater quality is largely controlled by pH and redox conditions (e.g., for arsenic, nickel, molybdenum, uranium and vanadium), and the mixture of different waste materials, including pyrite (acidic leachates) and carbonates (neutralizing and buffering pH). Analyses of shale waste from the deposit confirm the expected pyrite weathering with high concentrations of iron, nickel and uranium in the leachates. No general time trends could be distinguished for the groundwater quality from the monitoring in 2004–2019. This study has shown that black shale waste deposits can have a complex long-term impact on the surrounding environment.

Occupational monitoring at radioactive waste deposit

O Depósito Inicial de Resíduos Radioativos de Baixa Atividade - DIRBA é uma instalação auxiliar à Fábrica de Combustível Nuclear - FCN para o armazenamento inicial dos rejeitos radioativos de baixa geração gerado no ciclo do combustível nuclear sob responsabilidade da FCN. Atualmente são armazenados aproximadamente 460 tambores de 200 litros contendo resíduos Classe 2.3: Resíduos contendo Radionuclídeos Naturais (RBMN-RN). Como parte do licenciamento nuclear da instalação, um programa de monitoramento radiológico da área foi desenvolvido com monitoramento mensal de 17 pontos de exposição, 3 pontos de amostragem direta de longa distância com monitores CAM alfa-7, monitorados em janeiro e 9 pontos onde manchas de alfa emissores de meia-vida longa foram monitorados em janeiro.A taxa média de exposição entre os pontos foi de 0,5 μSv ∙ h -1 , com um máximo de 1,27 μSv ∙ h -1 variando, em média, entre 0,98 μSv ∙ h -1 no ponto P1 a 0 , 23 μSv ∙ h -1 no P11. A média mensal foi a mesma, 0,50 μSv ∙ h -1 , variando de 0,46 μSv ∙ h -1 (novembro) a 0,57 μSv ∙ h -1 (agosto). Como a alfa de meia-vida de longa duração estava todas abaixo do MDA, bem como os 9 esfregaços. Em relação às exigências das áreas monitoradas, o depósito deve ser considerado como área supervisionada, do ponto de vista da radioproteção.A possibilidade de tombamento dos tambores ou outros acidentes com derramamento de material neles contido fez com que, de forma proativa, uma área considerada considerada área controlada.

Tackling Lateral Variability Using Surface Waves: A Tomography-Like Approach

Lateral velocity variations in the near-surface reflect the presence of buried geological or anthropic structures, and their identification is of interest for many fields of application. Surface wave tomography (SWT) is a powerful technique for detecting both smooth and sharp lateral velocity variations at very different scales. A surface-wave inversion scheme derived from SWT is here applied to a 2-D active seismic dataset to characterize the shape of an urban waste deposit in an old landfill, located 15 km South of Vienna (Austria). First, the tomography-derived inverse problem for the 2-D case is defined: under the assumption of straight rays at the surface connecting sources and receivers, the forward problem for one frequency reduces to a linear relationship between observed phase differences at adjacent receivers and wavenumbers (from which phase velocities are straightforwardly derived). A norm damping regularization constraint is applied to ensure a smooth solution in space: the choice of the damping parameter is made through a minimization process, by which only phase variations of the order of the average wavelength are modelled. The inverse problem is solved for each frequency with a weighted least-squares approach, to take into account the data error variances. An independent multi-offset phase analysis (MOPA) is performed using the same dataset, for comparison: pseudo-sections from the tomography-derived linear inversion and MOPA are very consistent, with the former giving a more continuous result both in space and frequency and less artefacts. Local dispersion curves are finally depth inverted and a quasi-2-D shear wave velocity section is retrieved: we identify a well-defined low velocity zone and interpret it as the urban waste deposit body. Results are consistent with both electrical and electromagnetic measurements acquired on the same line.

ASSESSMENT OF STRONTIUM, RUBIDIUM AND SCANDIUM STATUS IN SOILS AFFECTED BY SOLID WASTE DEPOSITS

The aim of the study was to assess the level of contamination of soil with strontium, rubidium and scandium in the solid waste deposits. The study was performed on soil samples collected from Moldova Noua, southwest of Romania, an area with historical anthropogenic history. The soil analysis was performed using X-ray fluorescence (XRF). The samples were collected from five collection points using a random pattern from around the illegal waste deposit and all analyses were performed in triplicate. To assess the influence of wastes on the soils concentration levels of strontium (Sr), rubidium (Rb) and scandium (Sc), were calculated contamination factors (CF), and pollution index (PIL) by reporting the concentration of the investigated elements of the upper earth crust concentrations and geo-accumulation index (Igeo) calculated by reporting the elements concentration values to a control sample, used as reference. The reference sample was collected from an area close to the waste deposit but located in a protected green area. The results show that from the investigated elements, scandium is the element of concern, the soil presenting a moderate contamination level with this element.

Evaluation of a Multi-Isotope Approach as a Complement to Concentration Data within Environmental Forensics

Heavy metal contamination was identified in groundwater monitoring wells surrounding a waste deposit facility at the Rönnskär Cu–Pb–Zn smelter in Skellefteå, Northern Sweden, as well as in brackish water and sediments from the nearby harbor. Following an investigative study of the surrounding area, brackish water from the Baltic Sea and sediments from a nearby harbor were also determined to be contaminated. This study investigated the ranges of isotopic compositions of four elements (Cd, Cu, Pb, and Zn) in smelter materials (ores, products, and waste) and polluted groundwater sediments of the affected area. The study’s objective was to evaluate the variability of the polluting source and identify possible isotope fractionation. This study further assesses the viability of using isotopic information to identify the source of the pollutant. These data were used in combination with multi-element screening analysis and multivariate statistical techniques. Expanding the number of elements utilized in isotope tracing empowers our abilities to decipher the source(s) and the extent of environmental exposure from contamination events related to mining and refining operations.

Estimating Release of Trace Elements from an Area with Historical Open Pit Mining of Alum Shale Using Mass Transport and Element/Sulfate Ratios Calculations

Alum shale was mined for oil and uranium production in Kvarntorp, Sweden, 1942–1966. Remnants such as pit lakes, exposed shale and a 100-meter-high waste deposit with a hot interior affect the surrounding environment, with elevated concentrations of, e.g., Mo, Ni and U in the recipient. Today most pit lakes are circumneutral while one of the lakes is still acidic. All pit lakes show signs of sulfide weathering with elevated sulfate concentrations. Mass transport calculations show that for elements such as uranium and molybdenum the western lake system (lake Söderhavet in particular) contributes the largest part. For sulfate, the two western lakes contribute with a quarter each, the eastern lake Norrtorpssjön about a third and a serpentine pond system receiving water from the waste deposit contributes around 17%. Except for a few elements (e.g., nickel 35%), the Serpentine system (including the waste deposit area) is not a very pronounced point source for metal release compared to the pit lakes. Estimates about future water runoff when the deposit has cooled down suggest only a slight increase in downstream water flow. There could possibly be first flush effects when previous hot areas have been reached by water.