Top Soil Layer Research Articles

Arsenic variation in soil layers in Bandung Regency, Indonesia: A statistical approach for identifying potential sources

This research investigates the arsenic concentrations in 96 soil samples from a regency in Indonesia using a statistical approach. Soil samples were collected from three depth layers (topsoil [10–20 cm], subsoil [50–60 cm], and deep soil [90–100 cm]), with each layer consisting of 32 samples. Statistical analysis using SPSS was employed to analyze potential arsenic sources based on the proximity of study locations to geothermal system areas, land use, distance from industry, and the presence of study locations on fault lines.The findings indicate that the potential source of arsenic contamination in the soil are suspected to be associated with geothermal system activities and the presence of soil samples on fault lines. The arsenic concentration in locations near to the geothermal system (5-10 km) was 45 times higher (OR = 45, 95% CI = 45–362.57, p < 0.01). Arsenic was found to be 3.828 times higher in study areas situated on fault zones (OR = 3.828, 95% CI = 1.507–9.719, p < 0.01). Additionally, the research suggests that arsenic in the soil may also originate from anthropogenic activities, such as agriculture and industry, as the highest concentrations were found in subsoil or topsoil layers compared to deep soil. The variation in arsenic concentration from highest to lowest in agricultural soil layers was subsoil > topsoil > deep soil, whereas in residential soil, it was subsoil > deep soil > topsoil. The arsenic concentration variation at near distances from industrial areas was topsoil > subsoil > deep soil, contrasting with medium to far distances from industry (subsoil > deep soil > topsoil). Therefore, these findings can be utilized to prioritize remediation efforts and provide input for future research on arsenic contamination in the region.

Fate of dimethylsilanediol (DMSD) in soil-plant systems

Dimethylsilanediol (DMSD) is the degradation product of methylsiloxane polymers and oligomers such as volatile cyclic methylsiloxanes (cVMS). To better understand the environmental fate of this key degradation product, we conducted a three-part study on the movement of DMSD in soil. The objective of this third and final study was to determine the fate of DMSD in soil-plant systems under constant irrigation. Soil columns were constructed using two soils with the upper 20 cm layers spiked with 14C-labeled DMSD. Corn seedlings were transplanted into the soil columns and placed in a field plot underneath a transparent cover that prevented rainwater from reaching the soil columns while allowing soil water to be volatilized freely. The soil-plant columns were regularly irrigated with known amounts of DMSD-free plant growth solution to sustain the plant growth. At pre-determined time intervals (15–67 days), the plant and soil columns were sectioned and the distribution of 14Corganosilicon species in the soil profile and plant parts was determined using a combination of Liquid Scintillation Counting and High-Performance Liquid Chromatography-Flow Scintillation Analysis, while soil water loss was determined gravimetrically. It was found that the majority (>92 %) of DMSD initially spiked into the soil was removed from the soil-plant systems. Although DMSD was transported from the soil to the plant, it was subsequently volatilized from the plant via transpiration, with only a small fraction (∼5%) remaining at the conclusion of the experiments. In addition, little non-extractable DMSD was found in the top layer of soil in the soil-plant systems, suggesting that the air-drying of soil is a necessary pre-condition for the formation of such non-extractable silanol residue on topsoil.

Soil Aggregate Stability and Organic Carbon Content among Different Forest Types in Temperate Ecosystems in Northeastern China

Soil aggregates play a crucial role in substance and energy cycles in soil systems. The fixation of soil organic carbon (SOC) is closely tied to the safeguarding mechanisms of soil aggregates. Carbon fixation involves the conversion of atmospheric carbon dioxide into organic molecules by autotrophic organisms. Soil aggregates play a significant role in carbon stabilization, allowing for the physical occlusion of SOC. This study focuses on five forest types, Betula platyphylla, Betula dahurica, Quercus mongolica, Larix gmelinii, and mixed forests comprised of Larix gmelinii and Quercus mongolica, in the Heilongjiang Central Station Black-billed Capercaillie National Nature Reserve, northeast of China. This study investigated the soil aggregate stability (SAS) (water sieving) and aggregate-associated organic carbon (AAOC) at different soil depths in five forest types. Our findings demonstrated that fine macro-aggregates (0.25–2 mm) were the main types of soil aggregates among all the forest types. The SAS gradually decreased with increasing soil depth. Notably, broad-leaved forests exhibited relatively high soil stability. The fine macro-aggregates (0.25–2 mm) had the highest AAOC content, and the AAOC level was highest in the topsoil layer. The SAS and AOCC levels of the Betula platyphylla forest and Betula dahurica forest were higher than those of other forest types and were significantly affected by the forest type, soil depth, and soil physicochemical properties. Collectively, our findings reveal the key factors influencing aggregate stability and the variations in soil organic carbon content in different forest types. These observations provide a basis for studying the mechanisms of soil aggregate carbon sequestration, as well as for the sustainable development of forest soil carbon sequestration and emission reduction.

Identification of Lateritic Nickel Deposits Potential in the Kokoe Area, Kabaena Island, Central Buton Regency, Southeast Sulawesi Province, Indonesia

The study is situated in the Kokoe Region of Central Buton Regency, Southeast Sulawesi, specifically in the southern part of Kabaena Island. Its primary objective is to assess the potential of nickel laterite in the designated area. The research methodology involved microscopic analysis of bedrock using a polarizing microscope, examining the drilling data, including logging descriptions, and utilizing XRF geochemical analysis (Ni, Fe, Al2O3, Co, Mg, and SiO2) from 32 drilling sites. Both elementary grade and laterite profiles were visualized using Strater 5 software to simplify the representation of laterite profiles. Petrographic analysis divided the bedrock into two lithological units: serpentinized lherzolite and serpentinite. The laterite profiles in the study area were classified into four types: type A, type B, type C, and type D. Type A profiles consist of bedrock, saprolite, and limonite layers covered by clay and colluvium. Type B profiles lack limonite and instead exhibit saprolitic rock and rocky saprolite layers on top of the bedrock. Type C profiles comprise bedrock, saprolitic rock, rocky saprolite, limonite, and topsoil layers. Type D profiles contain three zones, namely bedrock, colluvium, and clay, but lack limonite and saprolite layers. Among the four profile types, type A and type C profiles show promising potential due to higher average grades of Ni and thicker saprolite zones compared to the type B and type D profiles.

Spatial relationship of landform surface features and biocrusts, and their effect on soil microbial biomass on an alluvial fan

AbstractThe spatial cover of biocrusts represents a suitable habitat for the activity of soil microorganisms in semi‐arid and arid regions. Microorganisms are one of the essential components of soil quality. Therefore, it is necessary to understand the processes of biocrust habitat formation in landforms and their mutual relationship with soil properties. We studied the spatial distribution of biocrusts and their effect on soil microbial biomass and carbon activity in a semi‐arid alluvial fan in NE Iran. A total of 72 soil samples (using plots 0.25 m2) from the topsoil layers (0–5 cm) were collected along the alluvial fan in September 2020. Soil surface properties and microbial biomass in two categories of biocrust and non‐biocrust were investigated in three classes of biocrusts coverage obtained by geostatistics. Our results revealed that biocrusts had a negative correlation with gravel coverage and elevation; in contrast, the suitable spaces for biocrusts growth were created by cobble clasts. The biocrusts have provided favourable conditions for soil microorganisms by altering the properties of the soil (such as increasing organic carbon, nitrogen and available phosphorus and decreasing pH), and thus they increased basal soil respiration and microbial biomass. Different microbial activities were led by the predominant type of biocrusts, as the chlorolichen crusts had the most significant effect on increasing the microbial biomass phosphorus while cyanolichen crusts increased the microbial biomass carbon. Moss and cyanolichen crusts increased microbial activity and respiration more than cyanobacteria crusts. Therefore, the soil quality has improved by biocrusts in semi‐arid ecosystems.

Interactive effects of long-term management of crop residue and phosphorus fertilization on wheat productivity and soil health in the rice–wheat

In the context of degradation of soil health, environmental pollution, and yield stagnation in the rice–wheat system in the Indo-Gangetic Plains of South Asia, an experiment was established in split plot design to assess the long-term effect of crop residue management on productivity and phosphorus requirement of wheat in rice–wheat system. The experiment comprised of six crop residue management practices as the main treatment factor with three levels (0, 30 and 60 kg P2O5 ha–1) of phosphorus fertilizer as sub-treatments. Significant improvement in soil aggregation, bulk density, and infiltration rate was observed under residue management (retention/incorporation) treatments compared to residue removal or residue burning. Soil organic carbon (SOC), available nutrient content (N, P, and K), microbial count, and enzyme activities were also significantly higher in conservation tillage and residue-treated plots than without residue/burning treatments. The residue derived from both crops when was either retained/incorporated improved the soil organic carbon (0.80%) and resulted in a significant increase in SOC (73.9%) in the topsoil layer as compared to the conventional practice. The mean effect studies revealed that crop residue management practices and phosphorus levels significantly influenced wheat yield attributes and productivity. The higher grain yield of wheat was recorded in two treatments, i.e. the basal application of 60 kg P2O5 ha–1 without residue incorporation and the other with half the P-fertilizer (30 kg P2O5 ha–1) with rice residue only. The grain yield of wheat where the rice and wheat residue were either retained/incorporated without phosphorus application was at par with 30 and 60 kg P2O5ha–1. Phosphorus levels also significantly affected wheat productivity and available P content in the soil. Therefore, results suggested that crop residue retention following the conservation tillage approach improved the yield of wheat cultivated in the rice–wheat cropping system.

Lightning-Ignited Wildfires and Associated Meteorological Conditions in Western Siberia for 2016–2021

The analysis of the spatio-temporal variability of lightning-ignited wildfires and meteorological conditions preceding their occurrence from both dry lightning and lightning with precipitation in Western Siberia for the warm seasons (May–September) of 2016–2021 was carried out. In the Arctic zone, fires from lightnings occur in most cases (83%) almost without precipitation (&lt;2.5 mm/day), whereas in the forest and steppe zones the number of cases is less (81% and 74%, respectively). The most significant changes in meteorological conditions before the ignition were also revealed in the northern part 3–4 days before. Among all considered parameters, the most important role in the occurrence of dry lightning-ignited wildfires belongs to mid-tropospheric instability, lower-tropospheric dryness, and the moisture content of the top soil and surface floor layer. Moreover, in the Arctic zone of Western Siberia, more extreme (hotter and drier) meteorological conditions should be observed for the occurrence of ignition from lightning. The threshold values for the considered meteorological parameters were derived for our region for the first time. Obtained results can be used in the development of models for potential fire hazards prediction in various landscapes, which will have a practical application in various spheres of the national economy.

Comprehensive evaluation of soil characteristics and carbon stocks variability in different urban land use types

The terrestrial environment generally serves as an important carbon pool. This study mainly assessed the properties and carbon storage capabilities of soils from different urban land uses. Soil samples from roads/highways, parks, institutional areas, and constructed wetlands were collected to assess the effects of soil sealing on the characteristics and carbon content of urban soils. Soil sealing and compaction greatly influenced urban soil properties by altering the mass-balance, thereby resulting in a disproportionate amount of inflow and outflow of compounds in the soil strata. Using the Walkley-Black and loss-on-ignition (LOI) methods of soil organic carbon (SOC) analysis demonstrated that LOI-based analysis yielded up to 26 times higher SOC values than the wet-oxidation method due to the high weight losses prompted by the volatilization of hygroscopic and structural water and thermal decomposition of carbonate-containing minerals. Further analyses indicated that open soils contain 5% to 78% higher percentage of organic carbon as compared with their sealed counterparts and top soil layers tend to have higher amounts of SOC due to the continuous deposition of carbon-containing compounds from external sources. Generally, the results of this inquiry can serve as a baseline for formulating strategies to augment pedologic carbon stocks in urban environments.

Partitioning the effects of coffee-Urochloa intercropping on soil microbial properties at a centimeter-scale

Conservation farming and crop diversity increase soil health, organic matter content, and soil microbial activity. However, the design and implementation of sustainable practices often lack a detailed understanding of their impacts on microbial communities in soil. Here, we studied the effects of an Arabica coffee (Coffea arabica) – Brachiaria (Urochloa spp.) intercropping system on soil microbial properties by partitioning at the centimeter-scale the topsoil layers. In particular, we collected and analyzed four soil layers in a vertical stratification gradient of 0–2.5 cm (layer 1), 2.5–5.0 cm (layer 2), 5–10 cm (layer 3), and 10–15 cm (layer 4). Soil samples were subjected to chemical analysis, bacterial community profiling, and quantification of microbial enzymatic activity for β-glucosidase and acid-phosphatase, in addition to the quantification of N-fixation and P-solubilization gene abundances. We found that intercropping increased acid-phosphatase activity at layer 1, β-glucosidase activity at layers 2 and 3, and the amount of soil organic matter and total magnesium at layers 2 and 3. Intercropping increased the relative abundance of the N-fixation gene at layer 3 and bacterial diversity at layers 1 and 3. Overall, intercropping significantly changed the soil bacterial community structure and resulted in a more interconnected co-occurrence network (i.e., greater node connectivity, network density, and lower edges average path length). Taken together, this study provides evidence for the positive impact of intercropping in the soil at a centimeter-scale vertical stratification. It corroborates the notion that plant diversity stimulates microbial activity and species interactions in soil.

Distribution of 226Ra and 210Po Radionuclides in Different Phases of Soil and Estimation of Their Annual Change Rates for Some Agricultural Soils

Human activities, such as plant cultivation, enhance the activity concentrations (ACs) of radionuclides in the topsoil and have the potential to affect humans and the environment. The soil with a high radiation background not only acts as a source of continuous radiation exposure to humans but also as a medium of migration for the transfer of radionuclides to food crops. Some spectrometers can measure the AC of radionuclides in the soil, but long‐term variation of AC is difficult to investigate. Therefore, developing methods for predicting the AC of radionuclides in agricultural soil is an interesting topic that many studies have focused on. In this work, a simple method was introduced to estimate long‐term changes of some radioisotopes in the top layer of soil (0–20 cm). The estimation considered four major processes: fertilization, irrigation, vertical leaching, and plant uptake. The leaching rates () of radionuclides were predicted by their ACs in the soil water and the infiltration rate of water in the soil. The method was applied to the soils of five study fields in southern Vietnam, and the values of 226Ra were between 7.4 Bq·m−2·y−1 and 60 Bq·m−2·y−1, while the rates of 210Po were between 22.1 and 111 Bq·m−2·y−1. For long‐term assessment, it was found that 226Ra increases in sweat potato soil and tomato soil with annual rates (ΔC) of 0.99 Bq·kg−1·y−1 and 0.69 Bq·kg−1·y−1, respectively. The AC of 210Po was predicted to increase in some soils. The corresponding ΔC values for 210Po were 0.028 Bq·kg−1·y−1 in rice, 0.617 Bq·kg−1·y−1 sweet potato, and 0.099 Bq·kg−1·y−1 in tomato soils. The results imply that interventions are necessary to reduce the radioactivity accumulation in fields with high ΔC values. The effective methods can be changing the fertilizer types and the irrigation systems.

Fractionation of stable boron isotopes in alfisols: Application of a novel tool for tracing boron behavior in two soil profiles

Available boron (AB) and total boron (TB) in soil have distinct isotopic values, which are mainly influenced by the pH, organic matter and clay minerals, and can be used to explore the chemical behaviors of boron (B) in adsorption, weathering and eluviation processes. The B isotopic compositions of AB and TB in brown soil (slightly acidic) and cinnamon soil (neutral to slightly alkaline) profiles were investigated by multicollector inductively coupled plasma mass spectrometry. Variations in pH value and organic matter in the two soils directly affected the adsorption of B isotopes (dissolved 11B(OH)3 or 10B(OH)4-) in the aqueous solution, as shown by AB having an average negative δ11B value of −1‰ and a great range of −10.83‰ to +8.32‰ in the cinnamon soil. Furthermore, the long-term effects of adsorption and transportation processes were evidenced by the large range of δ11BTB values (-24.22‰ to +21.07‰) in the two soils. The topsoil layers with more organic matter and higher δ11B values indicated that B isotope fractionation occurred as a result of the input of rainfall, recycling of plant litter and the adsorption of organic matter and clay minerals. The lower δ11B values, the higher B contents and the element ratios in the underlying layers resulted from the weathering of different minerals and the adsorption of AB in the leaching process. This finding is supported by the relationship between AB and the clay/silt ratio, with more negative δ11B values being associated with finer clay particles via the adsorption of 10B(OH)4- in a weakly alkaline soil solution. The δ11B values in soils may be a useful tool for distinguishing geochemical cycling and processes and characterizing long-term processes that are difficult to assess.

Effects of nitrogen reduction rates on grain yield and nitrogen utilization in a wheat-maize rotation system in yellow cinnamon soil

&lt;abstract&gt; &lt;p&gt;Excessive nitrogen (N) fertilizer application severely degrades soil and contaminates the atmosphere and water. A 2-year field experiment was conducted to investigate the effects of different N fertilizer strategies on wheat-summer corn rotation systems in yellow-brown soil areas. The experiment consisted of seven treatments: no N fertilization (CK), conventional fertilization (FP), optimized fertilization (CF), reduced N rates of 10% (90% FP), 20% (80% FP), 30% (70% FP), and a combination of controlled release with conventional urea at 7:3 ratio (CRU). The results indicate that under the condition of 80% FP, both CF and CRU treatments can increase the yield of wheat and corn for two consecutive years. Compared with FP treatment, the wheat yield of CF and CRU treatments increased by 3.62–2.57% and maize yield by 3.53–1.85% with N fertilizer recovery rate (NRE) of crops by 46.2–37.8%. The agronomic N use efficiency (aNUE) under CF treatment increased by 35.4–37.7%, followed by CRU, which increased by 30.5–33.9%. Moreover, compared with FP treatment, both CF and CRU treatment increased the content of organic matter (OM), total N (TN), and hydrolyzed N (HN) in the topsoil layer, and 70% FP treatment significantly reduced the HN content. Both CF and CRU treatments significantly increased the NO&lt;sub&gt;3&lt;/sub&gt; concentrations in the 0–20 cm soil depth during the wheat and maize season at maturity stages and decreased the residual inorganic N below the plow layer (40–60 cm). During the corn season, the CF and CRU treatments significantly reduced the NO&lt;sub&gt;3&lt;/sub&gt; concentration in the 40–60 cm soil layer from seedling to jointing. Considering various factors, CRU treatment under 80% FP conditions would be the best fertilization measure for wheat-corn rotation in yellow-brown soil areas.&lt;/p&gt; &lt;/abstract&gt;

Комплексная оценка состава и свойств чернозема южного мицеллярно-карбонатного, орошаемого ограниченно пригодными водами

Purpose: to take a comprehensive assessment of southern micellar-carbonate chernozem content and properties, irrigated with limitedly available water. Materials and methods. The research was carried out on the territory of a pilot site located in the Saki region of the Republic of Crimea near the village Chervonoye. During the work, the state of water resources used for irrigation and the soil were analyzed. The assessment of water suitability for irrigation was carried out on the basis of soil reclamation classification. The analysis of soil conditions included the determination of: bulk density and solid phase density, granulometric content, particle size distribution, pH, expanded salt content of the. When determining the agro-physical properties of the soil water extract, the following methods were used: pycnometric, drying to constant weight, cutting ring, sieve with water washing, pipette. Results. The topsoil layer was identified as compacted with satisfactory porosity. The nutrient supply was mainly characterized as medium and high, only low content was recorded in 2022 for nitrate nitrogen (0.3–0.7 mg/100 g of soil). Despite the use of limitedly suitable water for irrigation, no water-soluble salt accumulation was recorded in a meter layer of soil. At the end of the irrigation period in 2023, the soils were classified as non-saline, and according to their granulometric texture depending on the depth – as medium loamy, heavy loamy and light clayey. Conclusions. Despite the fact that in the period from 2022 to 2023, irrigation with water with a mineralization of about 1.5 g/l did not lead to the accumulation of water-soluble salts in the soil of the pilot site, it is recommended to organize regular observations of its salt regime. This is justified by the fact that in drier years the precipitation may not be enough to wash out the salts arriving during the growing season with irrigation water into the underlying horizons.

Adhesion theory and model for air humidity impact on dust emission

It has been suggested that air humidity influences dust emission under very dry conditions and adhesion might be the responsible process which changes the binding between soil particles. The process of adhesion is so far poorly understood and difficult to quantify. Here, a critical examination of the relevant studies is provided, and an adhesion model is proposed. Both isothermal-kinematic and diffusion processes can limit the soil liquid–water and water–vapor exchange in soil, but for the particle size range concerned in aeolian studies, diffusion appears to be the limiting process. The model shows that soil moisture in the topsoil layers is positively correlated with air humidity, but with delays of several hours. The model performance is influenced by several parameters but is particularly sensitive to the equilibrium soil water–vapor content. This implies that soil microscopic properties can strongly influence adhesion. A new formulation of soil water retention function covering the entire soil moisture range is also proposed, which links soil water retention function and pore size distribution. Using a relationship between soil particle-size and pore-size distributions, an adhesion-affected grain size can be estimated, which defines the upper size limit of soil particles influenced by soil moisture. This study explains how air humidity influences soil moisture through adhesion and dust emission and why low air humidity promotes the emission of finer dust particles.

The use of a geogrid – geotextile geo-composite to improve soft soils for construction works at a facility expansion site in Western Canada

Soft soils pose several challenges for construction works – from site accessibility and trafficability challenges, to earthworks, foundation design and other related challenges. This paper presents the use of a geocomposite reinforcement material to improve site accessibility and trafficability for a facility expansion project at a manufacturing and processing site in Western Canada. The soil stratigraphy at the site consisted of approximately 0.1 m to 0.8 m layer of organic topsoil (peat moss), underlain by soft lacustrine clay that extended up to depths of 11.5 m to 14.6 m below the ground surface. The soft surficial soils at the site made it challenging, or impossible in some areas, for the field investigation and construction equipment and crew to access the proposed construction areas. There was a high risk of equipment getting stuck or falling over in various areas, which had reportedly occurred during previous works on the site. To create a suitable working and trafficable surface for the required construction works, the geo-composite reinforcement material was placed directly on top of the stripped subgrade, followed by a 300 mm layer of compacted well-graded pit run. The use of the geo-composite reinforcement material helped to create the required stable working surface for equipment and crew to complete the construction of the facility expansion.

Modelling Impact of Land Use Changes and Climate on Soil Erosion in the Uma Oya River Basin, Sri Lanka

Soil erosion is a significant environmental issue in most mountainous areas and is further exacerbated due to ongoing climatic changes and anthropogenic activities. Soil erosion not only triggers natural disasters like landslides but also degrades the fertile topsoil layers. Therefore, modeling and evaluation of soil erosion in mountainous areas and river basins are highly important. The Uma Oya River Basin (UORB), Sri Lanka is an area with rich biodiversity and is also important for agricultural production. Moreover, this area is frequently discussed due to the ongoing developments of the Uma Oya Project. This paper presents a comprehensive evaluation of soil erosion in the UORB and results are compared for two decades from 2000 to 2020. The Revised Universal Soil Loss Equation (RUSLE) was used to determine the annual soil erosion rates. In addition, the spatial-temporal variation of land use and land cover was assessed in the UORB. Results revealed that extreme soil erosion scenarios occur when forests and other vegetation lands are converted to agricultural lands and farmlands. We found that soil loss in the area largely happened due to steep slopes, reduction of vegetation and forest covers, and growth of cultivation lands. Erosion-prone areas in the river basin are identified and conservation strategies are discussed. In addition, the impact of the ongoing climate change on the UORB is highlighted.

Assessing Horton and Kostiakov models focused on estimating soil water infiltration

Water infiltration into the soil plays key role in proper soil and water conservation and management processes. The aim of the current study is to assess water behavior in soil infiltration processes by using the Horton and Kostiakov models. Double-ring infiltrometer method was used to determine water infiltration into the soil. In addition, soil samples were collected at depths of 0-10 cm, 10-20 cm and 20-30 cm, to determine soil moisture. Cumulative infiltration (IA) and instantaneous infiltration rates per time interval (TiR) were calculated. Equations describing the investigated phenomena were adjusted, according to the Horton and Kostiakov models. High water infiltration rate was observed at the beginning of the process, likely due to low moisture level at the top soil layer. Both models tend to underestimate the initial infiltration rate value. However, the Horton model tends to overestimate most of the instantaneous infiltration values up to 25 minutes. The Kostiakov model, on the other hand, tends to overestimate most of the instantaneous infiltration rate values after 80 minutes. Despite the large fluctuation observed in TiR values in the soil, the assessed models have satisfactorily described the infiltration behavior at the experimental site. Based on the heat map analysis, the Kostiakov model was the one capable of determining the infiltration values closest to actual one.

Depth distribution of nano- and microplastics and their contribution to carbon storage in Chinese agricultural soils

The extensive and prolonged utilization of plastic materials in agriculture has primarily led to the accumulation of nano- and microplastics (NMPs, ≤5 mm) in farmland soils. The spatial-vertical distribution of NMPs mass concentrations and their impact on the national agricultural soil carbon reservoir remain unexamined. In this study, we quantified the residual mass concentrations of six prevalent plastic types in farmland soils around China using the double-shot model of thermal desorption/pyrolysis-gas chromatography–mass spectrometry (TD/Py-GC–MS). The results showed that median NMPs concentrations were 79.81 μg/g in the topsoil layer (0–15 cm), 57.17 μg/g in the middle soil layer (15–30 cm), and 32.90 μg/g in the bottom soil layer (30–45 cm). Overall, agricultural soil NMPs levels declined from the surface to deeper soil layers; however, some regions exhibit an opposite trend. Furthermore, our estimations indicate that carbon sourced from NMPs contributes to the agricultural soil carbon pool within a range from 0.004 % to 5.606 %, depending on the soil depth. As a hallmark of sustainable agricultural soil management, it is noteworthy that the concealed and continuously expanding carbon contribution of NMPs has an impact on soil carbon storage, albeit at a relatively low level. Our data serves as a foundational reference point and enables a precise evaluation of future contributions of NMPs to the storage of carbon in agricultural soils within China.

Analytical study of piles behavior for marine challenging substructures

Based on a new categorization, significancy and feasibility of vector-acting foundations for offshore challenging substructures are emphasized. A marine challenging status is typically related to loading, investigations, subsurface, environment, construction and sustainability requirements. The issue of the interaction of piles and complex subsoil is discussed in this paper. Three scenarios are studied comprising sensitive deposits at the full depth, the most impressive one, compressible deposits at the top layer and soft soil underlain by strong deposits. The role of CPTu records is addressed in recognition of problematic layers, geotechnical design and embedment depth designation. The effect of soil sensitivity on shaft and toe resistance is quantified through static analysis and reduction factors are suggested. Since bearing capacity, settlement and axial load are interactive, the neutral plane concept is applied, unifying the mentioned aspects. Through the neutral plane approach and considering the downdrag force due to the collapse of sensitive soil, primary design criteria incorporating sensitivity are discussed and quantified. Applying ground modification as a supplement for deep foundations is realized through two case studies, leading to enhancement in geotechnical performance. Overall, the mentioned phenomena must be discovered comprehensively in extraordinary conditions, aiming for a safe, reliable, knowledge-based and optimum design.

Effectiveness of Reducing Hardness in the Filtration Process Using Mixed Media with Detention Time Variations

The problem that is often faced in groundwater management, especially deep groundwater such as boreholes is hardness. This can happen because in the process of taking it from the soil through various layers of soil including limestone soil containing Ca and Mg, so that the water becomes hard. Hard water is found in areas where the top soil layer is thick and there is limestone formation. This study aims to identify the physical quality and hardness level of clean water sourced from dug wells and drilled wells, after treatment through filtration methods. Filtration is carried out using mixed media with variations in residence time in the filtration media, namely 30 minutes, 60 minutes and 90 minutes. The results showed that the effectiveness of reducing hardness in dug wells and drilled wells was highest for a variation in 90 minutes, For dug wells, the effectiveness of 90 minutes of residence time reached 9.18% and for drilled wells, the effectiveness reached 16.36%.