Anthropogenic Soil Research Articles

Humic-like acids from hydrochars: Study of the metal complexation properties compared with humic acids from anthropogenic soils using PARAFAC and time-resolved fluorescence

Humic acids (HA) play an important role in the distribution, toxicity, and bioavailability of metals in the environment. Humic-like acids (HLA) that simulate geochemical processes can be prepared by NaOH aqueous extraction from hydrochars produced by hydrothermal carbonization (HTC). HLA can exhibit properties such as those found in HA from soils, which are known for their ability to interact with inorganic and organic compounds. The molecular characteristics of HLA and HA help to explain the relationship between their molecular features and their interaction with metallic species. The aim of this study is to assess the molecular features of HA extracted from Terra Mulata (TM) and HLA from hydrochars as well as their interaction with metals by using Cu(II) ions as a model. The results from 13C NMR, elemental analysis, FTIR, and UV–Vis showed that HA are composed mostly of aromatic structures and oxygenated functional groups, whereas HLA showed a mutual contribution of aromatic and aliphatic structures as main constituents. The interactions of HA and HLA with Cu(II) ions were evaluated through fluorescence quenching, in which the density of complexing sites per gram of carbon for interaction was higher for HLA than for HA. Furthermore, the HLA showed similar values for stability constants, and higher than those found for other types of HA in the literature. In addition, the average lifetime in both humic extracts appeared to be independent of the copper addition, indicating that the main mechanism of interaction was static quenching with a non-fluorescent ground-state complex formation. Therefore, the HLA showed the ability to interact with Cu(II) ions, which suggests that their application can provide a new approach for remediation of contaminated areas.

Assessment of Evolutionary Trends in Mountain Grassland Soil Processes and Problems in Soil Protection and Their Rational Use

The objective of the survey was to assess evolutionary trends in the mountain-grassland soil processes and the environmental and anthropogenic impacts on soil degradation and land efficiency. Generalization of the previously studied materials in comparison with the data collected in route surveys carried out in the large river basins, including the Samur, Chirakhchai, Sulak, and other rivers, allowed for identifying the main factor affecting the evolutionary trends in the soil processes within the altitudinal zones in mountain regions in Dagestan. This is particularly the factor associated with both the climate and vegetation changes and the human economic activities. In addition, it has been proven that slope exposition and anthropogenic factors effect pedogenesis and soil degradation. Slopes of a southern exposition and the slopes of slightly different expositions from it are generally drier. Snow cover lasts for a long time, which is followed by rapid snowmelt. Therefore, the vegetation of such areas is poor, and, moreover, the occurred denudation processes are much stronger. According to the data collected on the basis of observations for the most recent 50 years, humus concentrations in the soils used in the economic circulation decreased by 0.5–1.2% and even by 1.5–2% in some of them. Annual soil washout comprises 12 million t on average. It involves approximately 50 thousand t of humus. Unregulated livestock grazing causes pothole formation, compaction by pathways, and sparse vegetation. Therefore, a 20–30% reduction in the projective vegetation land cover can induce a five- to sevenfold increase in the volume of eroded material in long-term erosion when compared to a 70–75% vegetation land cover. In addition, the current pedogenic processes are affected by global warming, differences in soil moisture and temperature regimes on slopes of different expositions in the altitudinal zonation system, and high erosion rates caused by natural and anthropogenic factors. Complex erosion-control measures, including amelioration by slitting once every 3–4 years, grazing regulation, and evenly distributed grazing with taking slope expositions into account, are required.

Identification of new microbial functional standards for soil quality assessment

Abstract. The activity of microorganisms in soil is important for a robust functioning of soil and related ecosystem services. Hence, there is a necessity to identify the composition, diversity, and function of the soil microbiome in order to determine its natural properties, functioning, and operating range as well as to assess ecotoxicological effects due to anthropogenic activities. Numerous microbiological methods currently exist in the literature and new, more advanced methods continue to be developed; however, only a limited number of these methods are standardised. Consequently, there is a need to identify the most promising non-standardised methods for assessing soil quality and to transform them into standards. In agreement with the “Ecosystem Service Approach”, new methods should focus more on soil microbial functions, including nutrient cycling and greenhouse gas emission, pest control and plant growth promotion, carbon cycling and sequestration, as well as soil structure development and filter function. The few existing standardised methods available that focus on the function of the soil microbiome mostly include measurements, like basal respiration, enzyme activities, and biodegradation of organic matter, under well-defined conditions in the lab. This paper sets out to summarise and expand on recent discussions within the International Organization for Standardization (ISO), Soil Quality – Biological Characterization sub-committee (ISO TC 190/SC 4), where a need was identified to develop scientifically sound methods which would best fulfil the practical needs of future users for assessing soil quality, going beyond the existing test systems. Of particular note is the current evolution of molecular methods in microbial ecology that use quantitative real-time PCR (qPCR) to produce a large number of new functional endpoints which are more sensitive as compared to “classical” methods. Quantitative PCR assesses the abundance of microbes that catalyse major transformation steps in nitrogen and phosphorus cycling, greenhouse gas emissions, chemical transformations including pesticide degradation, and plant growth promotion pathways based on the assessment of marker gene sequences that drive the related processes. In the assessment of soil quality methods, it was found that most methods focus on bacteria and related endpoints. Techniques to describe fungal communities as well as their functional traits are far less represented. As such, techniques to analyse fungal enzyme activities are proposed. Additionally, methods for the determination of microbial growth rates and efficiencies, including the use of glomalin as a biochemical marker for soil aggregation, are discussed. Furthermore, field methods indicative of carbon turnover, including the litter bag test and a modification to the tea bag test, are presented. However, it is obvious that with increasing developments in high throughput sequencing technologies and big data analyses, including metagenomics analysis, it will be possible to implement these technologies into the standardisation process for assessing the functions of the soil microbiome. Overall, it is suggested that endpoints should represent a potential function of soil microorganisms rather than actual activity levels, as the latter can largely be dependent on short-term variable soil properties such as pedoclimatic conditions, nutrient availability, and anthropogenic soil cultivation activities.

Revealing Tropical Technosols as an Alternative for Mine Reclamation and Waste Management

This study was based on the premise that Technosols constructed under tropical conditions are a valuable tool for inexpensive mine reclamation programs. These anthropogenic soils are still poorly studied in Brazil and are not recognized by the Brazilian Soil Classification System. Given the importance of mining to the Brazilian economy (the sector accounts for 20% of all products exported and 5% of the gross domestic product), there is an urgency to properly manage the large amount of waste produced. For this purpose, we suggest the use of Technosols as a strategy to overcome both land degradation and waste production by presenting a successful case of mine rehabilitation combining limestone wastes and tropical grasses. We show that Technosols constructed from the mine spoils can develop into soils suitable for agriculture in a few years, promoting land reclamation and producing food and energy. These soils are also valuable resources that can provide important ecosystem services, such as organic carbon storage.

ЭКОЛОГО-ГЕОХИМИЧЕСКАЯ ОЦЕНКА СОСТОЯНИЯ ПОЧВЕННОГО ПОКРОВА ТЕРРИТОРИИ СОРСКОГО ГОРНОГО-ОБОГАТИТЕЛЬНОГО КОМБИНАТА (РЕСПУБЛИКА ХАКАСИЯ)

Актуальность работы обусловлена необходимостью изучения воздействия горнодобывающих предприятий на компоненты природной среды. Особенно актуально проведение эколого-геохимической оценки территории Сорского горно-обогатительного комбината (Республика Хакасия), одного из главных предприятий России по добыче и переработке медно-молибденовых руд. Цель: оценка техногенной геохимической трансформации почв в зоне влияния медно-молибденового месторождения для разработки рекомендаций по проведению производственного геоэкологического мониторинга. Методы: масс-спектрометрия с индуктивно связанной плазмой (ИСП-МС). Результаты. Установлены уровни накопления тяжёлых металлов 1, 2 и 3 класса опасности в поверхностном горизонте почв и по глубине почвенного разреза (0–5, 5–20, 20–40 см) вблизи промышленной площадки (карьер и сопутствующие объекты), отвалов вскрышных пород, хвостохранилища, а также на удалении от них за пределами земельного отвода и санитарно-защитной зоны и на территории г. Сорска. Техногенная геохимическая специализация поверхностного слоя почв проявляется в повышенных уровнях накопления Mo (2–126 фонов), Cu (1,5–5 фонов), Mn (7–11 фонов), Cd, Pb, Ni, As, Zn (1,5–5 фонов). Содержание As превышает ПДКп от 2 до 10 раз. Поверхностный слой почв вблизи промплощадки имеет Mo-Mn-Cu-Cd-W-Pb геохимическую специализацию, в северо-восточном направлении от промплощадки и отвалов вскрышных пород – Mo-Mn-Ni- W, хвостохранилища – Mn-Mo-Ni, территория г. Сорска – Mo-Mn-W-Pb-Cd. Накопление Mo происходит в основном в поверхностном горизонте почв (0–5 см) и обусловлено преимущественно природными (геологическое строение) и техногенными (аэрогенное загрязнение во время буровзрывных работ, ветровая эрозия отвалов) факторами. В большинстве пунктов отбора почв выявлена закономерность увеличения содержания Ni, As, Cd, Sr, Cr, Cu и Zn по глубине почвенных разрезов от 0–5 до 20–40 см, что отражает специфику геологического строения территории. Выявлен высокий уровень загрязнения почв тяжёлыми металлами относительно фоновых значений в районе промышленной площадки, вблизи отвалов, а также на территории г. Сорска. Низкий уровень загрязнения определён в районе расположения хвостохранилища. В качестве рекомендаций для производственного геоэкологического мониторинга предложен перечень контролируемых тяжелых металлов. Выводы. Приоритетными элементами-индикаторами состояния почвенного покрова являются Mo, Cu, W, Cd, Pb, Ni, As, Zn. Учитывая факт, что исследования приводятся на территории медно-молибденового месторождения, содержание в почвенном покрове Mo и Cu неизбежно. При техногенной трансформации поверхностных горизонтов почв увеличиваются концентрации тяжелых металлов. Наибольшую техногенную нагрузку испытывают почвы в зоне влияния разработки карьера, отвалов. Увеличение содержание химических элементов с глубинной почвенных разрезов связано с особенностью геологического строения территории. Высокие уровни накопление элементов в верхнем горизонте почв связано с аэротехногенным загрязнением территории за счет переноса загрязняющих компонентов от основных антропогенных источников.

Resilience and microstructural resistance of Archaeological Dark Earths with different soil organic carbon contents in Western Amazonia, Brazil

Archaeological Dark Earths (ADE) are anthropogenic soils with high fertility and excellent physical conditions due to high soil organic carbon (SOC) content. However, climate change, land use and soil management can increase SOC mineralization, resulting in microstructure damage of these soils. To verify the effect of SOC loss, we collected deformed samples from the surface horizon and simulated the reduction of C with the application of 0.2, 0.4 and 0.6 ml of hydrogen peroxide 35% per gram of soil, resulting in three treatments of different oxidation levels and untreated soil. Both original and oxidized soil were submitted to an amplitude sweep test with controlled strain and a thixotropy test, in a compact modular rheometer. To characterize the effect of soil properties on rheology and resilience of ADEs, we performed a correlation analysis with physico-chemical properties from untreated soil. Higher clay and organic matter contents increased the microstructure elasticity of ADEs. The increase in base saturation, mainly due to the high Ca+2 content, also favors elasticity. The soil’s resilience is a result of the joint effect of particle size distribution, base saturation and SOC content. The microstructure recovers fast, regardless of the disturbance intensity. The SOC loss affected the microstructure differently in each ADE. These differences are not dependent on the amount of SOC lost and mostly labile SOC (as removed by low oxidation intensity) was responsible for soil strength.

Land-use evolution in the catchment of Lake Murten, Switzerland

Anthropogenic soil erosion is a problem of global concern and recently has become the focus of extensive research. In spite of this, our knowledge about the history of land-use and its long-term impact on soil erosion and the local environment remains limited. This study seeks to address this issue by investigating sediments of Lake Murten, Switzerland, using a multi-proxy approach to reconstruct the history of land-use and its impacts in the catchment. We analyzed pollen and charcoal to reconstruct past land-use and vegetation dynamics, and used the distributions of terrestrial leaf wax biomarkers, their δ13C isotopic composition and their soil retention time (compound-specific 14C) to evaluate long-term effects on past soil carbon dynamics.Arboreal pollen abundances, charcoal influx and cultural indicators match the archaeological evidence and reveal an eventful past around the lake. The first signs of human presence were detected around 5000 BCE, when Neolithic pile dwellers occupied the lake’s shores. However, human land-use had no significant effect on the pollen and the sedimentary organic matter (OM) composition during Neolithic times and the Bronze Age. This changed during the Late Iron Age and the Early Roman Period (ca. 70 BCE). Coincident with the rise of Aventicum, a Roman city, large-scale deforestation and agriculture began in the region. Severe soil degradation and outwash of soil organic carbon (SOC) at this time is documented by enhanced input of soil-derived and pre-aged leaf waxes, and resulted in cultural eutrophication ca. 2000 years ago. Soil erosion decreased after the fall of the Roman Empire and a short period of renaturation followed. Although the export of SOC returned to pre-Roman values after ca. 200 years, the forest never recovered to its past extent. The last two detected periods of land-use change correlate with the onset of Medieval agriculture (ca. 1000 CE) and the Industrial Period (ca. 1800 CE). Today, the mean transit time of leaf waxes is almost five times longer compared to the Roman Period, suggesting that substantial soil erosion has occurred and that an even longer time period would be necessary for the soil carbon dynamics to recover to their natural state.

Rapid photodegradation of terrestrial soil dissolved organic matter (DOM) with abundant humic-like substances under simulated ultraviolet radiation.

Solar ultraviolet (UV) radiation exhibits a significant degradation for dissolved organic matter (DOM) in natural water ecosystems. However, research on photodegradation process of terrestrial components (e.g., humic-like substances) of DOM are limited due to drastic water dilution and rapid degradation. Here, photochemical degradation of terrestrial soil DOM with abundant humic-like substances from different land use were investigated by utilizing spectral technologies. Simulated UV radiation caused obvious losses on concentration, component structures, and fluorescence characteristic of soil DOM samples. The correlations between absorption specific parameters (a280, SUVA254, and SR) and dissolved organic carbon (DOC) were especially pronounced (p < 0.05), which could be used as valid indicators to determine changes in DOM composition and molecular size during photobleaching process. The decreases of DOM fluorescence intensity were corresponded to first-order kinetic and half-life reactions. The greatest reduction on fluorescence intensity (31.56-81.97%) belonged to peak C (i.e., humic-like substances). Overall, DOM from forest and grass soil ecosystems was more easily photochemical degraded than anthropogenic soil DOM. Enhancive contribution of fresh DOM formed by photodegradation increased autochthonous characteristic and bioavailable nutrition by increasing biological index (BIX) values and ammonia nitrogen (NH4+-N) concentration. The slight microbial decomposition effects on DOM happened in unsterilized dark condition. Our findings provided insights for understanding the rapid photodegradation processes of composition and structure of terrestrial DOM. Graphical abstract.

Diuron Sorption, Desorption and Degradation in Anthropogenic Soils Compared to Sandy Soil

ABSTRACT: The aim of this study was to evaluate diuron sorption, desorption and degradation in two anthropogenic soils (Terra Preta de Índio - TPI) in contrast to a sandy soil (Quartzarenic Neosol - NQo). Sorption-desorption studies were performed by the batch equilibrium method and biodegradation in biometric bottles using radiolabeled diuron in 14C. Freundlich coefficient (Kf) values ranged from 13.50 to 50.41 µmol(1-1/n) L1/n kg-1 in TPI-2 and TPI-1, respectively, indicating very high diuron sorption in anthropogenic soils, following the order: TPI-1 ≥ TPI-2 &gt; NQo (99.10, 98.95 and 60.8%, respectively). Diuron desorption was very low in anthropogenic soils, ranging from 1.36 (TPI-1) to 1.70% (TPI-2), and 24% to NQo. Accumulated diuron mineralization to 14C-CO2 was &lt; 3% at 70 days after herbicide application, regardless of the assessed soil. Formation of 35 and 44% residue bound to TPI-2 and TPI-1 was observed, higher than to NQo (17%). In contrast, the residue extracted from NQo varied from 72 to 91%, ranging from 48 to 83% for TPI-1 and TPI-2 during the incubation period. The degradation half-life (DT50) of diuron in anthropogenic soils was of 66.65 and 68.63 days for TPI-1 and TPI-2, respectively, while a period of 88.86 days was observed for NQo. The formation of only one herbicide metabolite in all soils was evidenced. The application of diuron in arable areas in the presence of anthropogenic Amazonian soils may lead to inefficient chemical weed control, since these soils may reduce herbicide soil bioavailability due to high OC contents, where high sorption and low herbicide desorption are noted, as well as faster degradation compared to sandy soil.

The experimental investigation of behaviour of expanded polystyrene (EPS)

Low-strength substrates and anthropogenic soils are always an issue in civil engineering. Based on the soil layer types, several methods could be used to improve the basic/foundation layer however it would be difficult to make sure if the specified requirements are achieved. Nowadays, Expandable Polystyrene (EPS) as a lightweight material found as a substitution for traditional methods like soil replacement, soil mixing, using piles driving and other treatment techniques. This paper will demonstrate the static properties of EPS foams in a view point of construction material which will be a key for the future study of these materials. A series of compression tests were carried out on different types of EPS foam to study the effect of EPS geofoam density on the mechanical behaviour of these materials.

Distribution of heavy metals in anthropogenic soils: on the example of the industrial zone of Moscow

The article presents the results of the assessment of the distribution of heavy metals content in anthropogenic transformed soils of the industrial zone of Moscow. Excesses of norms are shown, geochemical associations are obtained. The work proved to exceed the maximum permissible concentrations of cadmium, lead, copper, nickel, zinc, arsenic for eleven test sites per 13.95 hectares of industrial zone in 57% of the obtained empirical data on the content of pollutants in the soil. In the investigated area, the contents of lead, copper, nickel and zinc are not uniformly distributed and are within wide range. No excess of the norm was recorded for mercury. The isolation of two geochemical associations of manmade genesis is justified. One association includes cadmium lead, copper, and zinc with the system-forming element copper. The other consists of nickel and mercury.

Methodology of estimation of forest-growing potential of soils and its approbation on the example of the Leningrad Region, Russian Federation

A progressive growth of anthropogenic soils and non-soil formations in the soil cover of the taiga forest zone and a general decrease in the ecological potential of soils necessitate the development of policies for the rational use of soil resources. The analysis of approaches to forest vegetation assessment of soils is carried out. The concepts of specific and resource potentials are introduced, and our own methodology for their assessment is developed. The methodology for calculating potentials was tested on the example of the Leningrad region, typical of the North-West of the European part of Russia and the North of the Russian Plain. Natural soil areas were calculated using a digital soil map. The analysis of changes in forest growing potential of soils is carried out from the beginning of intensive development of the territory to the modern period. These calculations can form the basis for assessing the potential contribution of the region to ensuring the reproduction of forest resources.

Concept of soil Red book of the Ukrainian Carpathians

The system and method of selection and documentation of soils that need to be included in the Red Book on the basis of research on natural and anthropogenic soils of the Ukrainian Carpathians were developed. Six categories of soil of the Red Book such as standards of typical, rare, endangered, cultivated and anthropogenic soils, unique soils have been proposed. Natural soils (typical, rare, endangered, unique) must functioned as soil etalons for changes evaluation that occur under the influence of forest management and recreational pressure, as well as protection of soil diversity. Etalons of cultivated soils play the role of models for agricultural lands; etalons of anthropogenic soils are used to determine the condition of land of urbo- and technocomplexes.

Vibration reduction techniques for Rapid Impulse Compaction (RIC)

New investments on anthropogenic soils bring the necessity for reliable and sustainable soil improvement methods. When the fill contains mainly non-cohesive soils and large thickness of material layers is considered, its physical properties can be improved by means of Rapid Impulse Compaction technology. Large energy of every impulse imposed by the mass of the hammer and drop height (with acceleration) makes it possible for relatively fast completion of works but causes large noise and severe vibrations. Environmental impact on adjacent structures may also cause some destruction and form the basis for legal claims. When serious damages appear in neighbouring buildings and structures, complains and claims are inevitable. Reduction of this negative impact may be achieved by means of technology calibration or other active and passive measures. The paper presents the description of that problem, some literature review and a case study describing how the intensity of vibrations may be to some extent reduced by means of hammer drop height reduction and digging a trench around the worksite.

Modeling of subsidence of anthropogenic soil containing ice lenses

The paper considers the possibilities of modelling of cyclic thermal effects on clastic water-saturated soil anthropogenic origin containing permafrost soil and ice lenses. In the formulation of the problem, there is uncertainty in the description of the structure of the layers, permeability coefficients, heat capacity and thermal conductivity. It is shown that the soil model allows the simultaneous implementation of filtration and convection modes depending on the degree of water cut in the layer. A formulation of the inverse problem is proposed, allowing an adequate interpretation of the log data.

New records of Lumbricidae and Collembola in anthropogenic soils of East European tundra.

The terrestrial environment of the East European tundra consists of a mosaic of habitat types. In addition to the natural habitat diversity, various human-influenced types may occur. In the town of Vorkuta, Komi Republic, Russia the manure-enriched soils near hydrogen sulfide springs were observed. This site represents an unusually nutrient-rich location with considerable development of organic soils, in contrast to the naturally forming soils in East European tundra which are typically thin and nutrient poor. In these organic soils, two species of Lumbricidae and two species of Collembola previously not recorded from the natural ecosystems in the study area of research territory were found. One earthworm species, Dendrodrilus rubidus tenuis, is likely to have been introduced. The presence of the three other species (Eiseniella tetraedra, Folsomia fimetaria, and Proisotoma minuta) is quite natural in East European tundra and such anthropogenic soils with high organic content may be a good habitat for them.

Environmental Impact of Exceptional Quality Biosolids Use in Urban Agriculture

Exceptional quality (EQ) biosolids may be used to rehabilitate anthropogenic soils for urban agriculture, but research on the environmental ramifications of applying biosolids at rates to improve such degraded urban soils is scarce. The objective of our study was to compare the impacts of EQ biosolids and inorganic fertilizer applied for rehabilitating anthropogenic soils on potential nitrogen (N) and phosphorus (P) water quality impairment risk. Three EQ biosolids (composted, air‐dried, and blended with woody mulch) were applied at agronomic N rates twice per year, and once per year at a disturbed land reclamation rate (5× agronomic N rate) for vegetable production to an anthropogenic, low‐fertility subsoil. A heat‐dried EQ biosolids and inorganic fertilizer control were applied at agronomic N rates only. Leachate P was below detection, and soil water‐extractable P concentrations were low. After 2 yr, reclamation rates resulted in soil P saturation ratios greater than the recommended 30% but lower than the 65% limit. The high Fe in biosolids, low soil initial P, and high pH, exchangeable Ca, and clay content, contributed to lower soluble P. Although nitrate N (NO3–N) posed the greatest nutrient leaching risk, lysimeter‐collected mass loading of NO3–N from reclamation rates was not greater than for the inorganic fertilizer. Relatively low NO3–N losses with reclamation rates could be due to denitrification or physical protection of organic N in the high‐clay soil. Our results indicate that reclamation rates of our EQ biosolids to anthropogenic, low‐fertility, clayey subsoils have low potential for N and P water quality impairment.Core Ideas Risk of phosphorus (P) loss was low even after high P biosolids applications. Cumulative nitrate loads were similar between reclamation rates and inorganic fertilizer. Dissolved organic carbon concentrations increased after biosolids reclamation rates. Large amounts of soil nitrogen accumulated 2 yr after treatment additions.

Contributions of artifactual materials to the toxicity of anthropogenic soils and street dusts in a highly urbanized terrain

A study was undertaken to test the hypothesis that the presence of fly ash and other artifactual materials (AMs) significantly increases the toxicity of urban soil and street dust. AMs were distinguished as artifacts (artificial particles > 2 mm in size), and particulate artifacts (≤2 mm in size); street dust was the <63 μm fraction of street sediments. Reference artifacts, street dusts, and topsoils representing different land use types in Detroit, Michigan were analyzed for miscellaneous radionuclides, trace elements, magnetic susceptibility (MS), and acetic acid-extractable (leachable) Pb. Background levels were established using native glacial sediments. Street sediments were found to have a roadside provenance, hence street dusts inherited their contamination primarily from local soils. All soils and dusts had radionuclide concentrations similar to background levels, and radiological hazard indices within the safe range. Artifacts, fly ash-impacted soils and street dusts contained elevated concentrations of toxic trace elements, which varied with land use type, but none produced a significant amount of leachable Pb. It is inferred that toxic elements in AMs are not bioavailable because they are occluded within highly insoluble materials. Hence, these results do not support our hypothesis. Rather, AMs contribute to artificially-elevated total concentrations leading to an overestimation of toxicity. MS increased with increasing total concentration, hence proximal sensing can be used to map contamination level, but the weak correlation between total and leachable Pb suggests that such maps do not necessarily indicate the associated biohazard. Home site soils with total Pb concentrations >500 mg kg−1 were sporadically toxic. Thus, these results argue against street dust as the local cause of seasonally elevated blood-Pb levels in children. Lead-bearing home site soil tracked directly indoors to form house dust is an alternative exposure pathway.

Intensification of exogenous geodynamic processes in areas with large linear objects, associated with changes in the characteristics of soils displaced by construction and operation activities

In the studied region, vast land areas are influenced by construction and operation of large linear facilities, such as oil-gas pipelines, power lines, motor roads and railways. In the areas along and inside the construction right-of-way zones, considerable changes occur in landscapes, microclimate conditions, hydrological features of water bo­dies, and geological engineering characteristics of the rocks. Furthermore, anthropogenic soil materials are produced. In our study, such materials are termed ‘man-made / technogenic soils’, which means the soil material displaced during stripping operations in the areas allocated for construction of linear objects, and the soil material resulting from coal mining and quarrying. The above-mentioned changes in the geological environment lead to intensive exogenous geodynamic processes (EGP) taking place during construction and in the first years of the object operation. In areas where such objects are located near and in residential areas, the EGP impact is observed in the zones that have been previously not at all influenced or only slightly affected by EGP. In our comprehensive study aimed at the assessment of the scale of the regional landslide and mudflow processes, the physical and chemical properties of technogenic soils were determined, their mineral and chemical composition was analyzed, and the levels of chemical contamination of the studied soils were estimated. The research results can be used in engineering-geological, construction, hydrometeorological surveys, as well as forecasting the development of EGP and their impact on the territory adjacent to the large linear objects.

Effects of pH Conditions and Application Rates of Commercial Humic Substances on Cu and Zn Mobility in Anthropogenic Mine Soils

We studied the effects of commercial humic substances derived from leonardite at different rates (0, 0.25, 2, 10 g kg−1) and pH (4.5, 6.0, 8.0) on Cu and Zn mobility, to evaluate their use for remediation of metal contaminated mine soils and to optimize their application conditions. We conducted a single-step extraction experiment and analyzed extracts for metal concentrations, soluble organic carbon and their E4/E6 ratio (ratio of absorption at 465 to 665 nm). Metal speciation in a soil solution was simulated by the non-ideal competitive adsorption-Donnan (NICA-Donnan) model. Increasing the amount of humic substances and the pH caused higher release rates of soluble organic carbon with a lower humic/fulvic acids ratio. This led to a higher mobility of metals (up to 110 times Cu concentration in control and 12 times for Zn) due to the formation of soluble metal-humic complexes. Speciation modeling predicted that increasing rates of humic substances would result in a higher proportion of Cu and Zn associated with fulvic acids, more mobile than the humic acids fraction. Application of commercial leonardite humic substances at 2–10 g kg−1 and with pH levels similar to or below natural soil could be useful for assisted-phytoextraction of contaminated anthropogenic soils. High rates of humic substances in more alkaline conditions could entail a considerable risk of metal leaching to groundwater, toxicity and transfer to the trophic chain.