Radiological characterization of the tailings of an abandoned copper mine using a neural network and geostatistical analysis through the Co-Kriging method.

The radiological characterization of soil contaminated with natural radionuclides enables the classification of the area under investigation, the optimization of laboratory measurements, and informed decision-making on potential site remediation. Neural networks (NN) are emerging as a new candidate for performing these tasks as an alternative to conventional geostatistical tools such as Co-Kriging. This study demonstrates the implementation of a NN for estimating radiological values such as ambient dose equivalent (H*(10)), surface activity and activity concentrations of natural radionuclides present in a waste dump of a Cu mine with a high level of natural radionuclides. The results obtained using a NN were compared with those estimated by Co-Kriging. Both models reproduced field measurements equivalently as a function of spatial coordinates. Similarly, the deviations from the reference concentration values obtained in the output layer of the NN were smaller than the deviations obtained from the multiple regression analysis (MRA), as indicated by the results of the root mean square error. Finally, the method validation showed that the estimation of radiological parameters based on their spatial coordinates faithfully reproduced the affected area. The estimation of the activity concentrations was less accurate for both the NN and MRA; however, both methods gave statistically comparable results for activity concentrations obtained by gamma spectrometry (Student's t-test and Fisher's F-test).

Wood ducks and hooded mergansers as interspecific brood parasites: An evaluation of parasitic egg survival.

Conspecific and interspecific brood parasitism are alternate reproductive strategies more pervasive in waterfowl than in any other group of birds. While previous research has measured costs incurred by nest hosts incubating parasitized clutches, few studies have focused on the relative success of parasites. Here, we evaluated the success of wood duck (Aix sponsa) and hooded merganser (Lophodytes cucullatus) eggs laid parasitically in Louisiana and Mississippi. We monitored nest boxes, assigned eggs in each nest as host or parasitic, and determined the number of eggs that hatched and failed. Across all study areas (1994-1999 and 2020-2023), we monitored 1750 wood duck and 377 hooded merganser nests; ~13% of wood duck and ~24% of hooded merganser nests were interspecifically parasitized. We modeled egg survival of 2925 host and 691 parasitic eggs from 197 successful nests (≥1 hatched egg, regardless of species). Wood duck eggs laid in hooded merganser nests had lower survival [0.293, CI = 95% credible intervals (after, CI) = 0.176, 0.439] than hooded merganser eggs (0.762, CI = 0.704, 0.810) laid in wood duck nests. Clutch size negatively influenced parasitic wood duck egg survival (ß = -.24, CI = -0.39, -0.10) but had a slight positive influence on parasitic hooded merganser eggs (ß = .08, CI = 0.04, 0.12). Our results revealed that hooded merganser eggs experience higher success when laid parasitically in wood duck nests, whereas wood duck eggs experience lower success when laid parasitically in hooded merganser nests. Our results reveal new complexity in waterfowl interspecific brood parasitism, where the success of parasitic eggs is species-, host-, and context-specific.

Elemental composition and potential health risk of vegetable cultivated in residential area situated close to abandoned gold mine dump: Characteristics of soil quality on the vegetables.

The presence of toxic metals in residential areas near abandoned gold mine tailings is a major environmental issue. This study mainly aimed to investigate the elemental distribution of both toxic and essential elements in soils and leafy vegetables (Brassica oleracea) collected from eight different sites around the Davidsonville residential area, located closer to the abandoned Princess gold mine dump, Johannesburg, South Africa. The nutritional value of vegetables in the human diet was determined to assess their value to their health. The vegetables contained metals in the following descending order: Ca > Mg > Ca > Sb > Pb > Fe > Mo > Cr > Se > As > V > Ni > Co > Cd. The bioaccumulation factor (BAF) revealed that vegetables tend to accumulate most metals even (toxic) during the transfer and translocation process. Based on the recommended daily allowance (%RDA) the vegetables showed to contribute 152%, 84% and 75% toward RDA for Se, V and Ca, respectively for most adults and these play a role in human metabolic activities. The vegetables were found to be a good source of essential elements (Ca, Mg, Ni, Na, Fe) but with some traces of toxic metals such as Pb, As and Sb. Based on the health risk assessment, the vegetable posed an adverse health hazard for human consumption due to metals with high HRI >1.

A framework for selecting and assessing soil quality indicators for sustainable soil management in waste dumps.

The primary objective of this study was to develop soil quality indexes (SQIs) to reveal the changes in SQ during the restoration of vegetation in the reclaimed waste dumps of the Hequ open-pit coal mine. The study built an SQI evaluation model for waste dumps based on the soil management assessment framework. The total data set (TDS) consisted of nine physicochemical property indicators. The selection of the minimum data set (MDS) involved the utilization of principal component analysis (PCA) and Norm values. The SQ was comprehensively evaluated for nine indicators, taking into account the non-linear membership function and the improved Nemerow index. The findings suggested a notable disparity in the SQ between the reclaimed area and the unreclaimed area, yet the overall SQ fell short. In the TDS index system, the organic matter has the highest weight and a greater contribution to the soil quality of the waste dumps. In the MDS indicator system, the weights of organic matter and total nitrogen are both 0.5. According to Nemerow index method, the average SQIN of 5 plots is calculated to be 0.4352 ± 0.194. The average value obtained from TDS is 0.581 ± 0.236, and the average value obtained from MDS is 0.602 ± 0.351. The weighted additive method was employed to compute three SQIs, all of which yielded satisfactory outcomes. And the above evaluation methods indicate that the overall soil quality level of the waste dumps is at a moderate level. The sequence of SQ in various waste dumps was as follows: No.4lower > No.1 > No.2 > No.3 > No.4upper. Specifically, the non-linear membership function indicated that pH, available nitrogen (AN), available phosphorus (AP), surface moisture content (SMC), and bulk density (BD) were crucial in limiting SQIs in total waste dumps. The crucial limiting SQIs in unreclaimed areas were total phosphorus (TP) and total nitrogen (TN). This analysis demonstrates its efficacy in formulating strategies for the SQ evaluation and targeted soil reclamation plans of waste dumps.

Quasi-3D slope stability analysis of waste dump based on double wedge failure.

The double wedges sliding along the weak layer of the foundation can be observed on the slope of the waste dump and the sliding body is divided into the active wedge and passive wedge by the weak foundation and the failure surfaces of the waste dump. Because the conventional limit equilibrium slice method cannot reflect the polygonal slip surface of the slope of the waste dump with weak foundation, this study proposed a double wedge calculation method for the slope of the waste dump with weak foundation. The limit equilibrium analysis is performed on double wedges by considering the direction and values of the interaction force between double wedges to obtain the safety factor of the slope of the waste dump. Meanwhile, the quasi-3D double wedges stability analysis method of the waste dump slope with weak foundation is proposed by considering the influence of the geometry and sliding direction of the slope surface on the slope stability. The safety factor of the inverted dump slope is 0.82, the volume of the sliding body is 6.43 million m3, and the main sliding direction is 20° south by east. The shear strain rate cloud diagram of the section is 'y' type distribution, and the sliding body is divided into two independent blocks. The safety factor of the sliding body section obtained by the double wedge method is between 0.76 and 0.92, and the closer to the boundary of the sliding body, the greater the safety factor of the section. The quasi-three-dimensional safety factor obtained by theoretical analysis is 0.817. The results show that the calculation results of quasi-3D double wedge are basically consistent with the calculation results of strength reduction method, while the proposed method is simpler. It can be used as a quick method to evaluate slope stability in engineering practice.

Evaluation of Enterococcus faecium NRRL B-2354 as a surrogate for Listeria monocytogenes during chlorine and peroxyacetic acid interventions in simulated apple dump tank water.

Sanitizers are widely incorporated in commercial apple dump tank systems to mitigate the cross-contamination of foodborne pathogens. This study validated the suitability of Enterococcus faecium NRRL B-2354 as a surrogate for Listeria monocytogenes during sanitizer interventions in dump tank water systems. E. faecium NRRL B-2354 inoculated on apples exhibited statistically equivalent susceptibility to L. monocytogenes when exposed to chlorine-based sanitizers (25-100 ppm free chlorine (FC)) and peroxyacetic acid (PAA, 20-80 ppm) in simulated dump tank water (SDTW) with 1000 ppm chemical oxygen demand (COD), resulting in 0.2-0.9 and 1.1-1.7 log CFU/apple reduction, respectively. Increasing the contact time did not affect sanitizer efficacies against E. faecium NRRL B-2354 and L. monocytogenes on apples. Chlorine and PAA interventions demonstrated statistically similar efficacies against both bacteria inoculated in SDTW. Chlorine at 25 and 100 ppm FC for 0.5-5 min contact yielded ~37.68-78.25 % and > 99.85 % inactivation, respectively, in water with 1000-4000 ppm COD, while ~51.55-99.86 % and > 99.97 % inactivation was observed for PAA at 20 and 80 ppm, respectively. No statistically significant difference was observed between the transference of E. faecium NRRL B-2354 and L. monocytogenes from inoculated apples to uninoculated apples and water, and from water to uninoculated apples during chlorine- or PAA-treated SDTW exposure. The data suggest E. faecium NRRL B-2354 is a viable surrogate for L. monocytogenes in dump tank washing systems, which could be used to predict the anti-Listeria efficacy of chlorine and PAA interventions during commercial apple processing. Further investigations are recommended to assess the suitability of E. faecium NRRL B-2354 as a surrogate for L. monocytogenes, when using different sanitizers and different types of produce to ensure reliable and comprehensive results.

Creep characteristics and discharge optimization of overlying river inner dump: A case study of Yuanbaoshan open-pit coal mine in China.

Overlying river can accelerate the creep of the inner dump, so to master the creep characteristics of the overlying river can provide a theoretical basis for mine safety and discharge optimization. Taking the overlying river inner dump of Yuanbaoshan open-pit coal Mine in China as the research object, a design scheme is proposed to divide it into rolling zone and non-rolling zone. Based on the creep model obtained by in-situ deformation monitoring and laboratory rheological test, the creep evolution law and deformation of overlying channel after soil discharge, slope morphology and advancing position are simulated and analyzed. The results showed that the creep variable in the (non-) rolling zone had a nonlinear upward trend with time, and the initial upward trend was large. The maximum vertical and horizontal creep in the rolling area was located in the middle and upper part of the rolling line, while the maximum vertical and horizontal creep in the dump was located in the middle and upper part of the non-rolling area, respectively. The post-construction settlement and horizontal discharging increased with the increase of the discharge height, and the convergence creep of the top ten years after construction increased approximately linearly with the decrease of the distance from the shoulder of the inner dump. The rolled sand and gravel backfill belonged to the foundation of uniform settlement deformation in general, and the change of slope shape had little effect on the deformation of the slope top in the rolled area. The geoglage elongation in the dam area met the requirements. On the premise of ensuring the stability of the dump, the slope angle of the inner dump can be appropriately increased to increase the capacity of the inner dump. The research results can provide guidance for the construction of inner dump in open pit.

Isotopic tracing of leachate percolation from municipal solid waste dump sites to groundwater in diverse climatic zones of India.

Groundwater resources in tropical regions are largely dependent on recharge by rainwater infiltration through soil layers with variable time. However, the rainwater infiltration through soil is a serious concern in urban tropics where it interacts with landfills at the dumpsites, potentially contaminating adjoining groundwater. In this study, the stable isotopic compositions of oxygen and hydrogen (δ18O and δ2H, respectively) in groundwater and leachates, adjoining municipal dumpsites in urban tropics (Bangalore, Kolkata and Durgapur located in diverse rainfall zonation of India), were analyzed to investigate their recharge sources and trace the possible mixing of leachate contaminants under three diverse climatology. The measured values of δ18O and δ2H suggested that the groundwater in these sites reflects higher recharge by rainwater. However, the d-excess values indicated secondary effects suggesting the groundwater has experienced significant modifications. The end member analysis using δ18O-d-excess relation pinpointed an additional leachate contribution from adjoining dumpsites. The critical fraction of leachate infiltration to groundwater quantified using two component mixing model ranged between (i) 1 and 33% in Bangalore, (ii) 5 and 13% in Kolkata and (iii) 18 and 76% in Durgapur, with its variability dependent on seasonality and aquifer connectivity. This information is crucial for groundwater management to secure water quality and to quantify potential hydrological contaminants particularly in drier seasons and drier regions, when and where the demand for groundwater is high, respectively.

Soil contamination around porphyry copper mines: an example from a semi-arid climate.

Extraction and processing of disseminated metalliferous ores, porphyry copper in particular, results in significant tonnages of waste and can cause severe disturbances and contamination in natural ecosystems. This is particularly important in semi-arid climates where natural soils are often deprived of organic matter and nutrients. This study was conducted on seven sites around Sungun Copper Mine, northwest Iran. Soil texture, EC, pH, and concentrations of nutrients, organic matter, along with 16 metal and metalloids were measured in 94 soil samples. Results showed a gradient of contamination from low contamination in natural hillsides to high contamination in mine waste depositories, Waste Dump and Oxide Dump, alongside Pakhir and Sungun Rivers. Nutrient deficiency occurred in disturbed sites. The main contaminant point sources were Waste Dump, mine pit drainage, and Oxide Dump. The results of Non-metric multidimensional scaling ordination showed elevated Cd, Zn, Fe, Cu, Pb, As, Mo, Mn, Co, S concentrations, high EC, and higher sand percentage in the sites affected by mine waste and acid mine drainage. Geo-Accumulation and Potential Ecological Risk Indices indicated that Pakhir riverside, Sungun riverside, and Oxide Dump have severe to moderate levels of environmental risks. Positive correlations between certain metal elements suggest common sources and similar reaction pathways, which may contribute to their similar geochemical behaviour in transport, deposition, and interdependence. Overall, the deficiency of organic matter and nutrients along with the soil sandy texture in contaminated sites of Sungun Copper Mine are the main limiting factors in managing metal mobility and soil remediation.

Enzyme kinetics of deoxyuridine triphosphatase from Western corn rootworm.

OBJECTIVE: The Western corn rootworm (WCR), Diabrotica virgifera virgifera, is a highly adaptable insect pest that has evolved resistance to a variety of control strategies, including insecticides. Therefore, it is interesting to examine how housekeeping proteins in WCR have been changed under WCR-controlling strategies. In this study, we focused on one of such proteins in WCR, a ubiquitous enzyme 5'-triphosphate nucleotidohydrolase (dUTPase). In the thymidine synthetic pathway, dUTPase hydrolyzes deoxyuridine triphosphate (dUTP) and supplies the substrate, deoxyuridine monophosphate, for the thymidylate synthase (TS). It decreases the cellular content of uracil, reducing uracil misincorporation into DNA. Suppressing the dUTPase activity, therefore, contributes to thymineless death. In this study, we investigated the enzymatic properties of dUTPase. RESULTS: The WCR dUTPase gene (DUT) was synthesized with the addition of His-tag corresponding DNA sequence and then cloned and expressed in Escherichia coli, and the protein product was purified. The product of WCR DUT hydrolyzed dUTP and was designated as dUTPase. WCR dUTPase did not hydrolyze dATP, dTTP, dCTP, or dGTP. WCR dUTPase was analyzed via size-exclusion chromatography and exhibited a molecular weight corresponding to that of trimer. The present format can be interpreted as nuclear trimer type. Possible isomers will be examined once transcriptome analyses are conducted.

Biovectoring of plastic by white storks from a landfill to a complex of salt ponds and marshes.

Research into plastic pollution has extensively focused on abiotic vectors, overlooking transport by animals. Opportunistic birds, such as white storks (Ciconia ciconia) often forage on landfills, where plastic abounds. We assess plastic loading by ingestion and regurgitation of landfill plastic in Cadiz Bay, a major stopover area for migratory white storks in south-west Spain. On average, we counted 599 storks per day moving between a landfill and a complex of salt ponds and marshes, where they regurgitated pellets that each contained a mean of 0.47 g of plastic debris, dominated by polyethylene. Modelling reliant on GPS tracking estimated that 99 kg and >2 million particles of plastic were biovectored into the wetland during 2022, with seasonal peaks that followed migration patterns. GPS data enabled the correction of field censuses and the identification of plastic deposition hotspots. This study highlights the important role that biovectoring plays in plastic transport into coastal wetlands.

Robust Localization for Underground Mining Vehicles: An Application in a Room and Pillar Mine.

Most autonomous navigation systems used in underground mining vehicles such as load-haul-dump (LHD) vehicles and trucks use 2D light detection and ranging (LIDAR) sensors and 2D representations/maps of the environment. In this article, we propose the use of 3D LIDARs and existing 3D simultaneous localization and mapping (SLAM) jointly with 2D mapping methods to produce or update 2D grid maps of underground tunnels that may have significant elevation changes. Existing mapping methods that only use 2D LIDARs are shown to fail to produce accurate 2D grid maps of the environment. These maps can be used for robust localization and navigation in different mine types (e.g., sublevel stoping, block/panel caving, room and pillar), using only 2D LIDAR sensors. The proposed methodology was tested in the Werra Potash Mine located at Philippsthal, Germany, under real operational conditions. The obtained results show that the enhanced 2D map-building method produces a superior mapping performance compared with a 2D map generated without the use of the 3D LIDAR-based mapping solution. The 2D map generated enables robust 2D localization, which was tested during the operation of an autonomous LHD, performing autonomous navigation and autonomous loading over extended periods of time.

A New Composite Material with Environmental Implications for Sustainable Agriculture.

Sewage sludge, also referred to as biosolids, consists of the by-products of wastewater treatment, which are a mixture of the water and organic and inorganic materials eliminated from wastewater sourced from domestic sewage industries during physical, biological, and/or chemical treatments. Biosolids are nutrient-rich organic materials resulting from the treatment of domestic wastewater in treatment plants. Sewage sludge can be considered a significant biological resource for sustainable agriculture. A new composite has been made consisting of soil, sewage sludge collected from the Galati Wastewater Treatment Plant, and slag from the Galati Steel Plant. This study aimed to investigate the structural, morphological, and chemical parameters of this composite through FTIR, SEM-EDX analysis, and XRF analysis. The samples had values of potential toxic elements that were within normal limits according to Directive 86/278/CEE, and, in terms of the iron-to-calcium ratio (I/C), all samples were of a low grade. This is the first time that slag has been added in a sewage sludge-soil combination, which can be an effective fertilizer replacement. Sewage sludge contains substantial amounts of organic matter, and slag reduces the contents of potentially toxic elements. In addition to these attributes, they may provide an opportunity for the beneficial re-use of sewage sludge and slag as resources in agriculture.

One-dimensional consolidation of highly saturated abandoned-soil under time-dependent stress: An analytical study.

A thorough knowledge of the consolidation behavior of highly saturated soil under time-dependent stress is essential for the design and construction of abandoned-soil dump sites in the soft soil regions of China. In this study, one-dimensional consolidation analytical solutions are derived for such soil under one-way and two-way drainage conditions, accommodating the time-dependent stress created by various dumping protocols. Representative soil samples are obtained, and consolidation tests are conducted with various saturation degrees (one-way drainage) and loading protocols (two-way drainage), to verify the consolidation equation and determine its range of applicability to various saturation degrees. The effects of layer thickness, dumping type, and compaction degree on the consolidation behaviors of highly saturated abandoned-soil dumps are investigated. The one-dimensional consolidation equation is applicable to soil with saturation degree not lower than 75% under instantaneous stress, stepped stress, and linear stress. The pore pressure distribution with depth is not symmetrical; the eccentric distance of consolidation degree increases with increasing layer thickness in the stress application stage and is approximately zero in the stress keeping stage. The pore pressure at middle of the soil layer increases with increasing layer thickness and decreases with increasing dumping rate from the completion of soil dumping. With increasing compaction degree, the middle pore pressure increases, while the surface settlement decreases. In the premise of the stability of an abandoned-soil dump, where the goals are to reduce post-construction settlement and to shorten the consolidation process of the entire soil layer, the important factors are smaller layer thickness, higher dumping rate, and larger compaction degree.

Examining the effect of spontaneous combustion on vegetation restoration at coal waste dumps after reclamation: Taking Medicago sativa L. (alfalfa) as an indicator.

The Spontaneous combustion problem poses a significant threat to the coal waste dumps after reclamation. Spontaneous combustion alters the soil environment and further affects vegetation growth. Therefore, it is essential to understand the response of vegetation and soil to spontaneous combustion for ensuring vegetation restoration. Here, taking the reclaimed plant type, Medicago sativa L. (alfalfa), as an indicator, this study carried out a field survey in a typical spontaneous combustion area (study area) of a coal waste dump after reclamation. A total of 41 soil and 70 vegetation sampling points were investigated in the field survey, including soil environmental factors (soil temperature, ST; soil water content, SWC; soil organic carbon, SOC; total nitrogen, TN; available phosphorus, AP; available potassium, AK; bulk density, BD; pH) and alfalfa growth indicator (above-ground biomass, AGB). The spatial variation of alfalfa AGB reached 69.9 %, and all soil environmental factors showed moderate variation (12.28-35.03 %) except for BD and pH. ST was found to have a strong explanatory ability on the variation of AGB in the entire study area (q = 0.62, p < 0.01), but the ability weakened with the improvement of the health grades of alfalfa (Grades A, B, C, and D). From Grade D to Grade A, the q-value gradually reduced from 0.71 (p < 0.01) to 0.05 (no significance). The interaction effects of soil environmental factors showed mostly bilinear and non-linear enhancement. In regions with severe vegetation degradation (Grade C and Grade D of alfalfa), the interaction of ST with BD, AP, AK, and TN played a dominant role in the spatial variation of alfalfa AGB (44.8-86.15 %). However, in the regions of Grade A and Grade B, the spatial variation of alfalfa AGB was mainly affected by the interaction effects of AK, TN, AP, and SOC (60.13-84.77 %). As a simple analysis method, Geodetector can help researchers to better understand the complex response mechanism of vegetation-soil under spontaneous combustion of coal waste dump. This study provides a theoretical reference for vegetation restoration of coal waste dumps.

Iron colloidal transport mechanisms and sequestration of As, Ni, and Cu along AMD-induced environmental gradients.

Colloids are common in mine waters and their chemistry and interactions are critical aspects of metal(loid)s cycling. Previous studies mostly focus on the colloidal transport of metal(loid)s in zones where rivers and soil profiles receive acid mine drainage (AMD). However, there is limited knowledge of the colloid and the associated toxic element behavior as the effluent flows through the coal waste dump, where a geochemical gradient is produced due to AMD reacting with waste rocks which have high acid-neutralization effects. Here, we investigated the geochemistry of Fe and co-occurring elements As, Ni, and Cu along the coal waste dump, in aqueous, colloidal, and precipitate phases, using micro/ultrafiltration combined with STEM, AFM-nanoIR, SEM-EDS, XRD, and FTIR analysis. The results demonstrated that a fast attenuation of H+, SO42-, and metal(loid)s happened as the effluent flowed through the waste-rock dump. The Fe, As, Ni, and Cu were distributed across all colloidal sizes and primarily transported in the nano-colloidal phase (3 kDa-0.1 µm). An increasing pH induced a higher percentage of large Fe colloid fractions (> 0.1 µm) associated with greater sequestration of trace metals, and the values for As from 39.5 % to 54.4 %, Ni from 40.8 % to 75.7 %, and Cu from 43.7 % to 56.0 %, respectively. The Fe-bearing colloids in AMD upstream (pH ≤ 3.0) were primarily composed of Fe-O-S and Fe-O-C with minor Al-Si-O and Ca-O-S, while in less acidic and alkaline sections (pH ≥ 4.1), they were composed of Fe-O with minor Ca-O-S. The iron colloid agglomerates associated with As, Ni, and Cu precipitated coupling the transformation of jarosite, and schwertmannite to ferrihydrite, goethite, and gypsum. These results demonstrate that the formation and transformation of Fe-bearing colloids response to this unique geochemical gradient help to understand the natural metal(loid)s attenuation along the coal waste dump.

Soil potentially toxic element contents in an area under different land uses in the Brazilian Amazon.

Soil pollution with potentially toxic elements (PTE) from incipient basic sanitation, dumps and industrial activities developed in the Amazon has been of international interest due to health and environmental issues. This study aimed to evaluate the concentration of PTE in five adjacent land occupations (a dump, a alumina refinery area and three residential centers) in the municipality of Barcarena, Amazon Region, Brazil. In a total area of 912 ha, 274 soil samples were collected at a depth of 0-0.2 m. Afterwards, the concentrations of As, Ba, Pb, Co, Cu, Cr, Hg, Ni and Zn were determined. The results were explored using descriptive and multivariate statistics, as well as geostatistical. Considering the data by location, maximum concentrations exceeding the prevention values of Brazilian soils were found for Cu, Ni and Zn in Dump (148; 42.8 and 356 mg kg-1), for Cu and Hg in Bom Futuro (333 and 1.99 mg kg-1) and for Cu in Itupanema (91.2 mg kg-1). Cu, Hg, Pb and Zn were grouped in the same principal component and showed the highest similarity measure in the cluster analysis. The interpolation point maps of the two principal components and of the individual concentrations of the PTEs showed the area of influence of the dump as the main reason for the increase in soil contamination. These results show the need for public policies aimed at the proper disposal of solid waste, in order to promote the reduction of pollutants in the soil, health and well-being for the local population, and also the environmental quality of the study area.

Folate Pathway Inhibitors, An Underestimated and Underexplored Molecular Target for New Anti-tuberculosis Agents.

The folate metabolic cycle is an important biochemical process for the maintenance of cellular homeostasis, and is a widely studied pathway of cellular replication control in all organisms. In microorganisms such as M. tuberculosis (Mtb), for instance, dihydrofolate reductase (MtDHFR) is the enzyme commonly explored as a molecular target for the development of new antibiotics. In the same way, dihydropteroate synthase (MtDHPS) was studied extensively until the first multidrug-resistant strains of mycobacteria that could not be killed by sulfonamides were found. However, the other enzymes belonging to the metabolic cycle, until recently less explored, have drawn attention as potential molecular targets for obtaining new antituberculosis agents. Recent structural determinations and mechanism of action studies of Mtb flavin-dependent thymidylate synthase (MtFDTS) and MtRv2671, enzymes that acts on alternative metabolic pathways within the folate cycle, have greatly expanded the scope of potential targets that can be screened in drug design process. Despite the crystallographic elucidation of most cycle proteins, some enzymes, such as dihydrofolate synthase (MtDHFS) and serine hydroxylmethyltransferase (MtSHMT), remain underexplored. In this review, we highlight recent efforts towards the inhibitor design to achieve innovative antituberculosis agents and a brief history of all enzymes present in the folate metabolic cycle. In the final section of this work, we have presented the main synthetic strategies used to obtain the most promising inhibitors.

Estimation of radiological impact of the activities of Olusosun Dump Site on workers and dwellers of Olusosun, in Lagos Southwest Nigeria.

This study assessed the potential radiological risks associated with the activities on Olusosun dump site on workers and dwellers of Olusosun community. The activity concentrations of 238U, 232Th and 40K from of soil and water samples were determined using High-Purity Germanium (HPGe) detector. The background radiation level of Olusosun dump site was measured using a portable Geiger-Müller counter-Radeye B20 survey meter. The mean value of background radiation was 1.46 mSv/yr. This value is about 46% higher than the recommended reference level of 1.0 mSv/yr for the public. The mean activity concentrations of 238U, 232Th and 40K in the soil samples were 19.1 ± 3.2, 29.1 ± 4.4 and 171.5 ± 6.1 Bq/kg respectively which are about 45.4%, 35.3% and 59.2% lower than the world's average levels. For the water samples, the mean activity concentrations obtained for 238U, 232Th and 40K are 0.4 ± 0.4, 0.8 ± 0.2 and 0.8 ± 0.3 Bq/l respectively. These are about 99.9% and 20% lower than WHO reference levels for 238U and 232Th. The mean absorbed dose rate in air (D), Annual effective dose (AED) outdoor, Radium Equivalent (Req), External hazard index (Hex) internal hazard index (Hin) and Excess lifetime cancer risk (ELCR) from soil samples were 33.6 nGy/h, 41.0 µSv/yr, 73.1 Bq/kg and 0.2, 0.3 and $1.4\times{10}^{-4}$, respectively. Absorbed dose in air D, AED outdoor, Req, Hex, Hin and ELCR are 41.1%, 41.4%, 80.3%, 80%, 75% and 50% lower than their corresponding world's average and references. The estimated AEDw from ingestion of water is 148.9 ± 50.4 µSv/yr, this is about 49% higher than the WHO reference level of 100.0 µSv/y from ingestion of water. The radiological hazard indices estimated from soil samples do not indicate any potential risks to the users. The elevated background radiation level of the dump site, and AEDw from ingestion of water, however, suggest that the activities on Olusosun dump site pose potential radiological risks on workers on the site and the public from consumption of water from Olusosun community.

Feral dogs in Chitral gol national park, Pakistan: a potential threat to the future of threatened Kashmir Markhor (Capra falconeri cashmiriensis) / Cães ferozes no parque nacional Chitral gol, Paquistão: uma ameaça potencial para o futuro do Markhor da Caxemira ameaçado (Capra falconeri cashmiriensis)

Abstract Feral dogs are well-organized hunters of ungulates in many parts of the world, causing great damage to wildlife populations and ultimately to the ecosystem. In Pakistan, the impacts of feral dogs on the wildlife have not been documented yet. In a period of fifteen years (2006-2020), feral dogs have killed hundreds of threatened markhor in Chitral gol national park (CGNP), Pakistan. Despite direct predation other impacts including disturbance and competition with other natural predators, could compromise conservation and management efforts. The population of feral dogs seems to have been increased with the increase of dumping sites by communities. Our findings suggest that there are pressing needs of controlling the feral dogs population and eradicating them from the core zone of CGNP and surrounding buffer communities. Conventional culling of dogs should be coupled with modern techniques like castration and sterilization. Communities should be educated regarding the clean environment, proper disposal of home wastes and, biodiversity conservation.

Resumo Os cães ferozes são caçadores bem organizados de ungulados em muitas partes do mundo, causando grandes danos à população de animais selvagens e, em última instância, ao ecossistema. No Paquistão, os impactos dos cães selvagens na vida selvagem ainda não foram documentados. Em um período de 15 anos (2006-2020), cães selvagens mataram centenas de markhor ameaçados no parque nacional Chitral gol (CGNP), Paquistão. Apesar da predação direta, outros impactos, incluindo distúrbios e competições com outros predadores naturais podem comprometer os esforços de conservação e manejo. A população de cães selvagens parece ter aumentado com o aumento dos locais de despejo pelas comunidades. Nossas descobertas sugerem que há necessidades urgentes para controlar a população de cães selvagens e erradicá-los da zona central do CGNP e das comunidades-tampão vizinhas. O abate convencional de cães deve ser combinado com técnicas modernas como castração e esterilização. As comunidades devem ser educadas sobre o meio ambiente limpo, o descarte adequado de resíduos domésticos e a conservação da biodiversidade.