Local Mining Research Articles

Magnetic inversion modeling of subsurface geologic structures for mineral deposits mapping in southeastern Nigeria

Magnetic inversion techniques have been implemented to infer the extension and geometry of magnetic structures and also evaluate its influence on mineralization within Abakaliki and its environs, southeastern Nigeria. The modeling approach considers the techniques of three-dimensional (3D) magnetic data inversion, Euler deconvolution, analytic signal inversion, Enhanced Local Wavenumber (ELW) Technique and Particle Swarm Optimization (PSO) to estimate source parameters and compare results. Model solutions were interpreted to represent possible geologic units with varying trends, housing mineralization within the study region. Results from inversion computation over some active mine locations show subsurface bodies with magnetic susceptibilities >0.00188 SI. Model results also show structural sources with almost 5.5 km depth extension, stretching 18 km in the EW direction at Ngbo – Ekerigwe location. This could imply significant mineral deposits at the location. Inversion of both magnetic anomaly and analytical signal enabled derivation of the actual subsurface structures in the region, with most of the structures appearing as dykes with depths ranging from 0.2 – 1.8 km at most of the mining sites. Location and depths of some of the modeled intrusions have been corroborated with the active on-site mines. The delineation of mineralization structures by this study would guide systematic exploration in the region.

Controls on sulfide accumulation in coastal soils during simulated sea level rise

A likely consequence of sea level rise during the next century will be progressive inundation of seawater through the current unsaturated zone in coastal-margin soils. It is unclear how this will change the biogeochemical cycling of iron, sulfur and carbon over different time scales and soil types. A long-term (540 day) laboratory experiment, slowly inundating intact coastal soil cores with seawater from the ‘bottom up’, was conducted to observe how coupled iron and sulfur dynamics change in different soil types. Pore water was extracted from the 60 cm cores at 10 cm depth intervals every 90 days and analysed for pH, electrical conductivity (EC), Fe2+, HS− and dissolved metals (Fe, Mn, As, Cd, Cu, Ni, Pb, Co, Zn) as well as stable sulfur (34S/32S) and radiogenic strontium (87Sr/86Sr) isotopes. Destructive solid phase analyses (for reactive Fe, acid volatile and chromium reducible sulfur (AVS and CRS) and total organic carbon (TOC)) were made at the start and end of the experiment. Iron and sulfate reduction was induced in soils with readily available TOC as anoxic conditions established, evidenced by statistically significant increases (P < 0.001) in dissolved Fe2+ and sulfide concentrations in porewaters, as well as simultaneous and progressive increase in the sulfur isotope (34S/32S) ratios. An increase in AVS indicated formation of metastable iron sulfide (FeS) minerals resulting from Fe2+ and sulfide in porewaters post inundation. This was supported by PHREEQC modelling of local mineral saturation states/indices in the system. Overall, the Fe2+ concentration increased to a peak at between 270 and 360 days, and then began decreasing at some depths, indicating slowing iron reduction, presumably because reactive iron (oxyhydro)oxides became progressively consumed by microbially driven reductive processes. However, microbially mediated sulfate reduction continued as abundant sulfate was still available from seawater. In the absence of free Fe2+, sulfide accumulated in the porewater, but only in those soils inundated the longest (>360 days), and with greater than 5% TOC. The combined use of sulfur (34S/32S) and strontium (87Sr/86Sr) isotopes supported the observed results, and represents a new and robust technique to quantify progressive sulfate reduction and seawater mixing phenomena in coastal soils. This study gives new insights into the biogeochemical cycling of sulfur and iron in soils experiencing seawater inundation from sea level rise over longer timescales. It is likely that sulfidisation (due to in-situ sulfate reduction) will begin to affect coastal wetland soils, especially in areas where TOC is high and where reactive iron depletes over time. This has potential consequences for sulfide toxicity in coastal soils and environments globally.

Estimation of in-situ rock strength from borehole geophysical logs in Australian coal mine sites

This study aims to improve the conventional empirical rock strength estimation method that is widely adopted in the Australian coal mining industry and provide more accurate rock uniaxial compression strength (UCS) predictions based on artificial neural network (ANN) models. 274 laboratory-measured UCS data (sample dimension: 60 mm (diameter) × 150 mm (height)) were collected from two longwall coal mines in Australia, along with the four geophysical logs (sonic, gamma, neutron, and porosity logs) and rock density of the tested core specimens. A two-layer ANN model was developed from these data based on the Levenberg–Marquardt algorithm as a base model. As compared to conventional sonic-UCS fitting equations, the mean percentage error, root mean squared error and maximum absolute error of the proposed ANN model were reduced from 34.27%, 15.23 MPa and 70.66 MPa to 20.67%, 11.02 MPa and 47.66 MPa, respectively. Further investigations were conducted by splitting the dataset based on rock lithology and mine locations, and separate ANN models were developed based on the divided subsets. Both lithology-specific and site-specific models exhibited improved estimation accuracy in comparison to the base model, indicating lithology and local geological conditions could considerably affect the estimation accuracy. Among the three types of models, the lithology-specific models yielded the most accurate predictions over the 274 data (MPE: 17.55%; RMSE: 8.84 MPa), followed by the site-specific models and the base model in descending order. Overall, all three models significantly outperformed the current empirical methods adopted in the studied mine sites. The outcomes of this study could provide more accurate UCS predictions for further geotechnical analysis in underground constructions, such as tunnel stability analysis and estimating in-situ stresses based on borehole breakout.

The use of gravel crushing siftings sands for the production of cast emulsion-mineral mixtures «Slarri Sil»

In the article, the authors present the main use results of mineral materials from local open cast mines for the cast emulsion-mineral mixtures making «Slarri Sil» for the protective wearing course installation for asphalt concrete pavements. The production of cast emulsion-mineral mixtures «Slarri Sil» using sand sifting from crushing local gravel materials was carried out on regional category III highways (according to traffic intensity) of the Amur Federal Highway passing through the Amur Region. In accordance with the requirements for mineral materials for the production of cast emulsion-mineral mixtures «Slarri Sil», it was ruled to use the sandy fraction of the stone crushing sifting products of igneous rocks in accordance with National State Standard 8736 with the following properties quality indicators: strength grade greater than or equal to 1200, abrasion grade greater than or equal to I-1, frost resistance grade greater than or equal to F50. Due to the limited number of deposits with siftings for crushing dense rocks and the length of regional highways in the Amur Region, deposits use for the production of cast emulsion-mineral mixtures throughout the entire route make the construction of wear layers unprofitable. The research objective is the local sand and gravel mix of the Zeya and Bureya rivers for the production of Slurry Seal type cast emulsion-mineral mixtures. The authors present the results of determining the physical and mechanical parameters and grain compositions of sands from siftings of crushing sand and gravel mix and rock for protective wear layers of asphalt concrete pavements. The results of determining the adhesion of the binder with the mineral part of cast emulsion-mineral mixtures «Slarri Sil» on various sands of crushing siftings are presented. The results of testing sands from siftings of crushing gravel and siftings of igneous rocks for wet abrasion are shown. The results of experimental studies made it possible to substantiate the use of sand from gravel crushing siftings for the construction of a protective wear layer for asphalt concrete pavement made of cast emulsion-mineral mixtures type «Slarri Sil» on the roads of the Amur Region, including federal ones. The obtained results were used to prepare the standard of the organization company standard — closed stock corporation «Asfalt» — 001-2012 «Production of works on the installation of protective wear layers for asphalt concrete pavements from cast emulsion-mineral mixtures of the Slurry Seal type».

Highly ion-conductive anion exchange membranes with superior mechanical properties based on polymeric ionic liquid filled functionalized bacterial cellulose for alkaline fuel cells

How to simultaneously improve the ionic conductivity and mechanical properties is a key problem facing currently used anion-exchange membranes (AEMs). Here, biomass-based bacterial cellulose (BC) was used as a porous template to make TiO2 localized mineralization around the surface of BC nanofibers, and constructed a TiO2-coated BC porous substrate (TiO2@BC) with hierarchical structure. Then, the coated TiO2 nanoparticles was densely grafted by quaternary ammonium groups to obtain high ionic conduction ability. After filling with a polymeric ionic liquid (PIL) with high ion exchange capacity through in situ polymerization and crosslinking, the obtained novel PIL-filled AEM possessed ultrahigh ionic conductivity of 100.5 mS cm−1 at 80 °C, which was 72.1% higher than that of the PIL-filled pure BC membrane (only 58.4 mS cm−1). Moreover, by the aid of the synergistic reinforcement effect of TiO2@BC, the membrane exhibited extremely high dry strength of 95.3 MPa and satisfactory wet strength and flexibility. When at fully hydrate state, the membrane with the size of 1 × 4 cm (width × length) can hang a bottle containing 1000 g of water. The single cell equipped with this membrane output the peak power density of 40.2 mW cm−2, showing its great potential as a high-performance biomass-based AEM.

Experimental investigations on the engineering properties of pozzolanic concrete reinforced with fibers and the reduction of CO2 emissions: A case study on local mineral pozzolan

Experimental investigations on the engineering properties of pozzolanic concrete reinforced with fibers and the reduction of CO2 emissions: A case study on local mineral pozzolan

Local mineral resources and agricultural production wastes as fertilizer

The paper contains the studies of the influence of diatomite (high-silica rock) in its pure form and diatomite-based organic-mineral fertilizer and chicken manure on the barley yield. It was found that these fertilizers contributed to an increase in the barley grain yield by 0.12 and 0.26 t/ha (depending on the dose) when using diatomite and by 0.5 and 0.73 t/ha – organic-mineral fertilizer. The organic-mineral fertilizer based on diatomite and chicken manure was superior in effectiveness to the mineral one (N40P40K40).

Effect of past century mining activities on sediment properties and toxicity to freshwater organisms in northern Sweden

The release of toxic metals from local mining activities often represents a severe environmental hazard for nearby lake ecosystems. Previous studies on the impact of mining have primarily focused on single lakes, with less emphasis on spatial and temporal recovery patterns of multiple lakes within the same catchment, but with different hydrological connection and distance to the pollutant source. This knowledge gap prevents us from assessing the real environmental risk of abandoned mines and understanding ecosystem recovery. This study explores the intensity and spatial patterns of sediment contamination and the potential for ecosystem recovery in three lakes in close vicinity of a lead (Pb) and zinc (Zn) mine in Sweden that has been inoperative for >20 years. Dated (210Pb and 137Cs) sediment cores from each lake were used to reconstruct temporal patterns in trace element deposition and relate those with past mining activities. Results show that all lakes were affected by mining, indicated by increasing Pb and Zn concentrations and decreasing organic matter content, at the onset of mining. However, the extent and timing of mining impact differed between lakes, which was partly ascribed to differences in the historical use of tailings and settling ponds. Assessment of toxicity levels in sediments, based on normalized Probable Effect Concentration Quotient (PEC-Q) to organic matter content, provided more consistent results with the historical mining than conventional methods, showing a decreasing impact in lakes once the operations ceased. Still, sediment Pb concentrations were > 10 times higher than pre-mining values, evidencing the urgent need for remediation actions in the study lakes. This study highlights the importance of considering spatial heterogeneity in metal deposition, sediment organic matter content, and hydrological connectivity with tailings when risk assessments are performed in mining-impacted lakes. The use of normalized PEC-Q in toxic assessments is also recommended.

Path Planning for Unmanned Delivery Robots Based on EWB-GWO Algorithm.

With the rise of robotics within various fields, there has been a significant development in the use of mobile robots. For mobile robots performing unmanned delivery tasks, autonomous robot navigation based on complex environments is particularly important. In this paper, an improved Gray Wolf Optimization (GWO)-based algorithm is proposed to realize the autonomous path planning of mobile robots in complex scenarios. First, the strategy for generating the initial wolf pack of the GWO algorithm is modified by introducing a two-dimensional Tent-Sine coupled chaotic mapping in this paper. This guarantees that the GWO algorithm generates the initial population diversity while improving the randomness between the two-dimensional state variables of the path nodes. Second, by introducing the opposition-based learning method based on the elite strategy, the adaptive nonlinear inertia weight strategy and random wandering law of the Butterfly Optimization Algorithm (BOA), this paper improves the defects of slow convergence speed, low accuracy, and imbalance between global exploration and local mining functions of the GWO algorithm in dealing with high-dimensional complex problems. In this paper, the improved algorithm is named as an EWB-GWO algorithm, where EWB is the abbreviation of three strategies. Finally, this paper enhances the rationalization of the initial population generation of the EWB-GWO algorithm based on the visual-field line detection technique of Bresenham's line algorithm, reduces the number of iterations of the EWB-GWO algorithm, and decreases the time complexity of the algorithm in dealing with the path planning problem. The simulation results show that the EWB-GWO algorithm is very competitive among metaheuristics of the same type. It also achieves optimal path length measures and smoothness metrics in the path planning experiments.

Four decades of regional wet deposition, local bulk deposition, and stream-water chemistry show the influence of nearby land use on forested streams in Central Appalachia

Hydrologic monitoring began on two headwater streams (<1 km2) on the University of Kentucky's Robinson Forest in 1971. We evaluated stream-water (1974–2013) and bulk-deposition (wet + dust) (1984–2013) chemistry in the context of regional wet-deposition patterns that showed decreases in both sulfate and nitrate concentrations as well as proximal surface-mine expansion. Decadal time steps (1974–83, 1984–93, 1994–2003, 2004–2013) were used to quantify change. Comparison of the first two decades showed similarly decreased sulfate (minimum flow-adjusted annual-mean concentration of ≈13.5 mg/L in 1982 to 8.8 mg/L in 1992) and increased pH (6.6–6.8) in both streams, reflecting contemporaneous changes in both bulk and wet deposition. In contrast, concentrations of nitrate (0.14 to >0.25 mg/L) and base cations increased between these two decades, coinciding with expansion of surface mining between 1985 and 1995. In 2004, stream-water pH (6.7 in 2004), sulfate (9.2 mg/L), and nitrate (>0.11 mg/L) were similar to 1982, despite wet-deposition concentrations being lower. Base-cation concentrations were higher in the stream adjacent to ongoing surface mining relative to the stream situated near the middle of the experimental forest. However, pH decreased to approximately 5.7 by 2013 for both streams, which, combined with a shift in dominant cations from calcium to magnesium and potassium, indicates that the soil-buffering capacity of this landscape has been exceeded. Ratios of bulk deposition and stream-water concentrations indicate enrichment of sulfate (1.7–25.2) and cations (0.5–64.8), but not nitrogen (0.1–5.6), indicating that the Forest is not nitrogen saturated and that ongoing changes in water-quality are sulfate driven. When concentrations were adjusted to account for changes in streamflow (climate) over the 4 decades, external influences (land management/regulation) explained most change. The amount and direction of change differed among constituents, both between consecutive decades and between the first and last decades, reflecting the influence of localized surface mining even as regional wet deposition continued to improve due to the Clean Air Act. The implication is that localized stressors have the potential to out-pace the benefits of national environmental policies for communities that depend on local water-resources in similar environments.

Spatial Distribution Pattern and Pollution Evaluation of Heavy Metals in Farmland Soil in Guangxi

Farmland soil is an indispensable natural resource in agricultural production. A macro analysis of the spatial distribution and pollution level of heavy metals can provide a scientific basis for future farmland pollution control. Based on the measured data of heavy metals in farmland soil in Guangxi since 2014, the spatial distribution characteristics of 6 heavy metals in farmland soil, namely Pb, As, Cd, Cr, Zn and Cu, were discussed, and the pollution status was evaluated using the geo accumulation index method. The results showed that the average values of Pb, As, Cd, Cr, Zn, Cu in farmland soil were higher than the background values of farmland soil in Guangxi. The average contents of Pb, As, Cd, Zn in farmland soil exceeded the soil environmental quality standard (GB15618-2018), and Cr and Cu did not exceed the standard; The spatial distribution characteristics of heavy metals in farmland soils in Guangxi are obviously different. Generally, the content of heavy metals in the middle and north regions is higher than that in the south regions; The land accumulation index is in the order of Zn>Pb>Cd>As>Cu>Cr, in which the average <i>I_geo</i> values of As, Cu and Cr in farmland soil are all less than 0, while affected by local mining activities, the average <i>I_geo</i> values of Zn, Pb and Cd in soil are higher.

Hydrochemical characteristics and water quality assessment of snow cover in the northeastern tibet plateau

Snow cover as an important water resource is essential for regional water environment system. The Three-Rivers Headwater Region (THR) in the Tibetan Plateau is the source of the Yellow River, the Yangtze River and the Lantsang River with fragile ecological environment and large snow cover. The analysis of hydrochemistry in snow cover can provide reliable data for the research of environmental changes. Snow cover samples in 57 sites across the THR region were collected, and arsenic (As) and major ions were analyzed to investigate the distribution characteristics. The snow cover samples were weakly alkaline with water type of SO4–Cl–Ca–Mg. The As concentration varied from 0.24 to 6.12 μg/L with average value of 1.25 μg/L. Major ions and As have similar distribution characteristics, with higher levels in the northern part of the study area due to anthropogenic influence and special geography. Qualitative and semi-quantitative analysis of snow cover samples based on principal component analysis and absolute principal component score-multiple linear regression indicated that As was substantially controlled by burning of fossil fuels and local mining activities, while major ions mainly derived from terrestrial dust, human activities and marine sources. Although there were different trajectories at the sampling points, the air mass in THR was mainly controlled by the westerly circulation. The water quality of THR was excellent with water quality index <50. This work will shed lights for the migration and transformation of pollutants in the Tibet Plateau and for assessing the impact of human activities on geochemical cycling of pollutants.

Pengaruh Pengambilan Keputusan Lokasi Pertambangan Batu Bara terhadap Dampak Lingkungan

Selecting a mining location is a matter that is so important in determining the location of a coal mine that must be chosen by a mining company. Several factors or criteria must be considered in determining the location of a coal mine, including soil material content, determination of the UPS (Ultimate Pit Slope), size and maximum depth limitation at the end of the pit, operation, ladder/bench dimensions, geographical and geological conditions, road geometric conditions and drainage system selection depend on groundwater conditions and rainfall in the mine area. From an environmental point of view, coal mining has an impact on changing landscapes, decreasing soil fertility, threats to biodiversity, decreasing water and air quality, and environmental pollution. Once operational, mines and acid mine drainage also remain in the mining industry. Former coal mines can have positive and negative impacts on the environment related to water quality and quantity. The purpose of this study is to determine the effect of choosing a coal mining location on environmental impacts. The method used in this research is the previous research review method. In which the researcher's efforts to find comparisons, then become inspiration for further research. Then, previous research helps the researcher position the research and prove the originality of the research.&#x0D; Keywords Mining, coal, impact, environment

IDENTIFIKASI MINERAL LOGAM LAYAK TAMBANG BERDASARKAN ANALISA SPECTROMETRI X-RAY FLUORESCENCE DAERAH ABAI BAGIAN UTARA, KECAMATAN SANGIR BATANG HARI, KABUPATEN SOLOK SELATAN, PROVINSI SUMATERA BARAT

Solok Selatan is already known as an area that has potential precious metal, Gold. Local mining scale can be found on site certain areas in Abai Region, especially in the North, which was previously believed to exist the presence of these minerals. Based on the consideration of associated mineral associations gold, of course the presence of other precious metals deserves further investigation such as Copper (Cu), Silver (Ag), Lead (Pb), Zinc (Zn) and Titanium (Ti). Exploration activities and geochemical analysis need to be carried out to determine the characteristics of the associated metallic minerals of Gold in Abai Region. A series of explorations carried out with a direct mapping mechanism to determine the topography, morphology, local geology, distribution of lithology and type of gold deposit. The collected samples will be tested in a chemical laboratory to determine gold content, chemical composition, and other metallic minerals. This research is expected to be able to answer the characteristics of the material (mineral) based on the geochemistry of precious metal compounds and can recommend better management in the presence of other precious metals.

Anthropogenic activity and millennial climate variability affect Holocene mercury deposition of an alpine wetland near the largest mercury mine in China

Mercury (Hg) is a potentially toxic element that can be transported globally through the atmosphere, once deposited in the environment, has strong bioaccumulation and extreme toxicity in food webs, especially in wetland ecosystems. Anthropogenic Hg emissions have enhanced Hg deposition by 3–5 times since the industrial revolution, and the mining and smelting of Hg ore are important emission sources. However, the dynamics in Hg deposition around the largest Hg mine in China before the industrial revolution and their driving forces remain poorly explored. Here we reconstruct the atmospheric Hg depositional fluxes (named here Hg influx (Hginflux)) during the Holocene using a 450-cm alpine wetland sediment core taken from the Jiulongchi wetland, which is only 65 km to the Wanshan Mercury Mine. Our record shows an abrupt rapid increase in Hg concentration since 2500 cal yr BP, suggesting that Hg mining in southwest China may have started before the establishment of the Qin dynasty. Two major Hginflux peaks were found during the periods 10,000–6000 and 6000 - 3800 cal yr BP, with an increase in Hg deposition by a factor of 4–8. These two peaks are also found in other terrestrial archives from several sites across the Northern Hemisphere. We speculate that critical millennial-scale climate changes, i.e., the Holocene Climatic Optimum (HCO) and the Mid-Holocene Transition (MHT), were the potential triggers of these two Hginflux peaks. This study highlights the importance of climatic variability and local Hg mining in controlling atmospheric Hg deposition during the Holocene.

Effects of water-coal interactions on coal mine water quality in China: a lixiviation experiment and actual water quality investigation.

Water-coal interactions are dominant factors that affect water quality in coal mines. Using lixiviation, the effects of water-coal interactions on pH, salinity, and hazardous elemental enrichment in coal mine water and associated trends were simulated and analyzed. The salinity and hazardous element contents were low in the alkaline solution filtrate. However, the salinity and contents of hazardous elements (As, Cr, Zn, Cu, Mn, Co, Ni, Cd, Pb, U, and Be) in acid solution filtrate increased significantly with a decrease in pH. The pH of the solution filtrate was affected by the mineral composition of the coal, wherein the pyrite content could generally determine the pH. In addition, the spatial distribution and utilization potential of coal mine water quality in China was determined based on water quality data surveys. For water-deficient regions in northern China, particularly in the northwest, the local mine water had high salinity, a high pH, and a low content of hazardous elements; therefore, the reuse of mine water for water consumption is feasible. Conversely, the mine water in the southwest region had high salinity and a low pH and was enriched in harmful elements with potential ecological and health risks. The actual water quality characteristics of the coal mine water matched the results of the laboratory simulation analysis, confirming the effect from water-coal interactions. This work provides a reference for understanding the determinants of coal mine water quality and the potential for water environment protection.

Preparation and characterization of foamed concrete using a foaming agent and local mineral resources from Burkina Faso

The paper describes lightweight-foamed concretes (LFC) that were formulated from cement, natural sand, and foam from a foaming agent with densities of 600 and 700 kg/m3. The identified mineral phases in the cement are alite, belite, Celite, ferrite, calcite, and gypsum. The obtained foamed concretes have a porosity varying from 29.17 to 37.14 vol%, a thermal conductivity below 0.2 W/m.K, and a mechanical strength greater than 2 MPa. At 28 days setting, the relative quantities of crystalline and amorphous phases were identified by XRD and DTA/TG. These techniques allowed to show the importance of the carbonation process and hydrated phases formation on the macroscopic strength increase. The microstructural characterization by image analyses evidences that when the density decreases, growth of both crystalline and amorphous phases in the bubble walls during setting is a mean of compensating the role of density in strength.

Rent-Seeking and Criminal Politicians: Evidence from Mining Booms

AbstractWe study how natural resource rents affect the selection and behavior of holders of public office. Using global price shocks to thirty-one minerals and nationwide geological and political data from India, we show that local mineral rent shocks cause the election of politicians charged with serious crimes. We also find a moral hazard effect: politicians commit more crimes and accumulate greater wealth when mineral prices rise during their terms in office. These politicians have direct influence over mining operations but no access to fiscal windfalls from mining; we thus isolate the direct political impacts of mining sector operations.

How big is the footprint? Quantifying offsite effects of mines on boreal plant communities

Threats from mining to the biodiversity and ecological services of boreal forests are increasing as demand for minerals increases globally. However, much less is known about how offsite effects of mines affect understory communities as they occur outside the immediate location of mining and are often overlooked during ecological evaluations. We conducted an extensive field survey along 1-km transects surrounding six mine sites of different mining stages (operating vs non-operating), that crossed four ecosystem types (deciduous, coniferous, mixed forests and open canopy) in Canada’s boreal forest. The offsite effects of mines on the understory were quantified using vascular plants (woody and herbaceous), bryophytes and lichens. Mine offsite effects impacted understory diversity and composition. Understory richness and cover was more reduced near operating than non-operating mines. Mining stage mainly significantly altered understory diversity and community structure in deciduous and mixed forests while understory communities were more resistant to the offsite effects in coniferous forest (P > 0.05). The footprint was quantified using the influenced distance and the strongest effects were generally within 0.2 km from mines. Given the predicted changes in boreal forest ecosystems with encroachment of deciduous species into coniferous forests and the increased sensitivity of mixed and deciduous forests, the area affected by offsite effects of mines could grow in the future. We suggest that offsite effects should be included in ecological evaluations.

HLHUI: An improved version of local high utility itemset mining

High utility itemsets (HUIs) have been emerged to address the main problems of frequent itemset mining, namely considering the same importance for all items of the dataset and ignoring the occurrence numbers of items within transactions during the mining process. Local and peak HUIs were defined to mine the itemsets which are useful and high utility during specific periods of time. In this paper, using some adopted definitions and strategies of HMiner [19], an improved version of LHUI method [33], called HLHUI (Hminer-based Local HUI mining), is introduced that mines local HUIs using a utility-list-based approach. Performance evaluations of the proposed method show that it can efficiently find useful itemsets.