Composition Of Topsoil Research Articles

Little owl (Athene noctua) pellets enhance seed germination under salinity stress in two leguminous plant species

ABSTRACT As central-place foragers, owls accumulate prey remains, in the form of rejection pellets, around their roosting and nesting sites, which may modify top soil composition and influence seed germination. However, the effects of owl pellets on seed germination still remain understudied. In this study, we conducted germination assays on two plant species from south Tunisia to assess whether a prior treatment of the seeds with the filtrate of little owl (Athene noctua) pellets affected germination rates under different salinity conditions. Results showed enhanced germination in pellet-treated seeds compared to untreated seeds. Pellet treatment was also associated with reduced inhibitory effects of salt on seed germination. Moreover, at the scale of a little owl territory, the concentrations of organic matter and total nitrogen in the top soil were higher at the nesting site compared to a nearby unused site, providing some evidence of a fertilizing effect of pellets. Overall, our findings suggest that little owls play a significant role in shaping plant dynamics and ecosystem functioning in arid North African areas, where the soil is poor and threatened by salinization. We suggest that little owls may be relevant actors in eventual restoration and rehabilitation plans of degraded ecosystems in these areas.

Impact of Climate on Soil Organic Matter Composition in Soils of Tropical Volcanic Regions Revealed by EGA-MS and Py-GC/MS.

Soil organic matter (SOM) crucially influences the global carbon cycle, yet its molecular composition and determinants are understudied, especially for tropical volcanic regions. We investigated how SOM compounds change in response to climate, vegetation, soil horizon, and soil properties and the relationship between SOM composition and microbial decomposability in Tanzanian and Indonesian volcanic regions. We collected topsoil (0-15 cm) and subsoil (20-40 cm) horizons (n = 22; pH: 4.6-7.6; SOC: 10-152 g kg-1) with undisturbed vegetation and wide mean annual temperature and moisture ranges (14-26 °C; 800-3300 mm) across four elevational transects (340-2210 m asl.). Evolved gas analysis-mass spectrometry (EGA-MS) documented a simultaneous release of SOM compounds and clay mineral dehydroxylation. Subsequently applying double-shot pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) at 200 and 550 °C, we detailed the molecular composition of topsoil and subsoil SOM. A minor portion (2.7 ± 1.9%) of compounds desorbed at 200 °C, limiting its efficacy for investigating overall SOM characteristics. Pyrolyzed SOM closely aligns with the intermediate decomposable SOM pool, with most pyrolysates (550 °C) originating from this pool. Pyrolysates composition suggests tropical SOM is mainly microbial-derived and subsoil contains more degraded compounds. Higher litter inputs and attenuated SOM decomposition due to cooler temperatures and lower soil pH (<5.5) produce less-degraded SOM at higher elevations. Redundancy analyses revealed the crucial role of active Al/Fe (oxalate-extractable Al/Fe), abundant in low-temperature/high-moisture conditions, in stabilizing these less-degraded components. Our findings provide new insights into SOM molecular composition and its determinants, critical for understanding the carbon cycle in tropical ecosystems.

A survey of soil elemental variability in Singapore parks for forensic purposes

Soil, as a surviving trace after contact and transfer between contacting surfaces at a crime scene, can be recovered and analyzed to infer the presence of persons or tools at the scene and prior activity leading to its deposition. With its vast diversity and heterogeneity, it varies in composition from place to place, providing a basis for trace examiners to distinguish visually similar-colored soils. Unlike countries with native topsoil, Singapore’s urban lands are commonly filled with man-altered and man-transported soil, with relatively little known about the variations of soil’s characteristics within a small, localized area. The current study surveyed the soil’s elemental variability in Singapore parks, which are green spaces for public leisure use. Past installations of recreational facilities and landscaping with fast-growing vegetation in parks inevitably cause disturbance to the original natural soil and mixing with extraneous soil, further contributing to the heterogeneity of the park’s topsoil composition. In our sampling approach, visually similar-colored surface soils were collected from within a 1-m2 site, sites in proximity within a park, and parks across Singapore. The collected soils were dried and sieved into clay- and silt-size fractions for elemental analysis using WDXRF and SEM/EDS. To examine the extent of the spatial elemental variability, we adopted three-sigma interval match criteria and a discriminative model incorporating relative data, square root values and the Canberra distance measure for data processing and pairwise comparison of soil samples. The study also aimed to develop soil databases encompassing soils across Singapore with the intent of understanding the value of soil evidence within a local context.

Application of Cu isotopes to identify Cu sources in soils impacted by multiple anthropogenic activities

Copper (Cu) is an important micronutrient for animals and plants, but it is toxic at high concentrations in soil. Soils adjacent to industrial areas would be subjected to severe Cu pollution. Identifying Cu sources in the surface environment is crucial for understanding their pollution level and fate. This study investigated Cu content, isotope composition of topsoils, and two soil profiles with varying levels of Cu contamination and related potential Cu sources in southwest China. The difference in Cu isotope compositions of tailing (1.29 ± 0.08 ‰), smelting fly ash (0.04 ± 0.03 ‰), coal (2.44 ± 0.09 ‰), coal-burning fly ash (0.34 ± 0.03 ‰), and geogenic soil (0.10 ± 0.03 ‰) enabled us to distinguish anthropogenic Cu from geogenic Cu. The plot of δ65Cu and 1/Cu demonstrates that Cu of the polluted soils was from three end-members: the smelting fly ash, the vehicle exhaust, and the background soils. Based on the mass balance model, we calculated that the fly ash from smelting was the major anthropogenic source, contributing approximately 29 % of Cu contamination in soils, and the diesel exhaust was another important source, with a contribution rate of approximately 25 %. Additionally, soil profile results suggest that anthropogenic Cu could transport through soil profiles and influence Cu content and isotope signatures of subsurface soils, at least to a depth of ∼60 cm. Finally, our research indicates that Cu isotopes could be a promising tool for tracing industrial pollution, as significant Cu isotope fractionation would occur during the smelting process. Our research highlights the contribution of smelting and diesel exhaust to Cu contamination in the soils in a representative mining area. These findings serve as a scientific foundation for the development of policy for pollution control in industrial-affected regions.

Development of a Soil Organic Matter Content Prediction Model Based on Supervised Learning Using Vis-NIR/SWIR Spectroscopy.

In the current scenario of anthropogenic climate change, carbon credit security is becoming increasingly important worldwide. Topsoil is the terrestrial ecosystem component with the largest carbon sequestration capacity. Since soil organic matter (SOM), which is mostly composed of organic carbon, and can be affected by rainfall, cultivation, and pollutant inflow, predicting SOM content through regular monitoring is necessary to secure a stable carbon sink. In addition, topsoil in the Republic of Korea is vulnerable to erosion due to climate, topography, and natural and anthropogenic causes, which is also a serious issue worldwide. To mitigate topsoil erosion, establish an efficient topsoil management system, and maximize topsoil utilization, it is necessary to construct a database or gather data for the construction of a database of topsoil environmental factors and topsoil composition. Spectroscopic techniques have been used in recent studies to rapidly measure topsoil composition. In this study, we investigated the spectral characteristics of the topsoil from four major rivers in the Republic of Korea and developed a machine learning-based SOM content prediction model using spectroscopic techniques. A total of 138 topsoil samples were collected from the waterfront area and drinking water protection zone of each river. The reflection spectrum was measured under the condition of an exposure time of 136 ms using a spectroradiometer (Fieldspec4, ASD Inc., Alpharetta, GA, USA). The reflection spectrum was measured three times in wavelengths ranging from 350 to 2500 nm. To predict the SOM content, partial least squares regression and support vector regression were used. The performance of each model was evaluated through the coefficient of determination (R2) and root mean square error. The result of the SOM content prediction model for the total topsoil was R2 = 0.706. Our findings identified the important wavelength of SOM in topsoil using spectroscopic technology and confirmed the predictability of the SOM content. These results could be used for the construction of a national topsoil database.

Trace metal accumulation in agricultural soils from mineral phosphate fertiliser applications in European long‐term field trials

AbstractMineral phosphate (P) fertilisers are the main suspected sources of uranium (U) and cadmium (Cd) input to agricultural soils. This study was set up to survey the general long‐term impact of P fertilisers on concentrations of Cd, U and other trace metals in European soils. A total of 218 soil samples was collected from 15 long‐term (3–78 years, median 18 years) P trials at 11 locations with a pairwise comparison of topsoil composition between the fertilised and corresponding unfertilised soils. Aqua regia soil extraction detected the effects of fertilisation more sensitively than the HF (real total) soil extraction. Statistically significant differences in aqua regia soluble metals due to fertiliser application were detected more frequently for U (10 of 15 trials) than for Cd (4 of 15 trials). The concentrations of U and Cd in soil linearly increased with cumulative applied P across all soils and sites; a total addition of 1 ton P ha−1 increased the mean topsoil (23 cm depth) concentrations by 0.11 mg U kg−1 soil (0.09–0.12 mg U kg−1, 95% CI) and 0.03 (0.02–0.04) mg Cd kg−1 soil. These results correspond with mass balance predictions (1 ton P ha−1; +0.15 mg U kg−1 soil and +0.02 mg Cd kg−1 soil) based on previously determined average trace element concentrations in European fertilisers. Data thus suggests that, on average among trials, losses of Cd from soil are undetectable. In contrast, about 30% of the theoretical U input from fertilisers is lost in the same trials. This study provides data to better evaluate the modelled trace metal accumulations in soil and to evaluate the prevailing metal limits in mineral fertilisers.Highlights U and Cd accumulation in agricultural soils correlates with cumulative mineral P‐fertiliser dose. Accumulation of fertiliser‐derived U is more often detectable compared to Cd. Due to its accumulation potential, U accumulation should be monitored. Aqua regia soluble concentrations better detect metal accumulation in soil than real total concentrations.

Altitudinal variation of trace elements deposition in forest ecosystems along the NW side of Mt. Amiata (central Italy): Evidence from topsoil, mosses and epiphytic lichens

Mt. Amiata (1738 m) is a volcanic peak in central Italy, completely covered with native oak, chestnut and beech forests. In this Natura 2000 site of Community Importance overlying a large shallow aquifer, climate change and the long-range transport of nutrients and contaminants might have negative impacts on relict plants populations and spring water chemistry. To evaluate the atmospheric deposition of trace elements in Mt. Amiata forest ecosystems, we analyzed the elemental composition of topsoils, epiphytic lichens (Parmelia species) and epigeic moss (Hypnum cupressiforme) between 120 and 1730 m a.s.l. along the NW side of the mountain, which is scarcely affected by natural and anthropogenic sources of metals. The elemental composition of the topsoil is mainly influenced by the different lithologies of the study area (calcareous up to an elevation of 700 m, volcanic up to the summit) and only Pb concentrations increased significantly with the altitude. The total element concentrations in cryptogams, particularly net of the possible contribution from soil particles, showed an enhanced accumulation of Pb, Cd, Hg and Zn in samples collected at altitudes above 1300 m, where beech forest are frequently shrouded in clouds and fog and receive more snow and rain than the lower chestnut and oak woods. Interestingly, the older and metabolically inactive tissues at the base of moss shoots, which are usually overlooked in biomonitoring surveys, appeared to behave as long-term accumulators of Pb. The possible mechanisms involved in the increased bioaccumulation of Mn in cryptogams inhabiting chestnut woods are discussed.

Clay mineralogy of soils from lower atrai basin of Bangladesh

The lower Atrai basin, the study area, lies in the Agroecological Zone-5 (AEZ-5) of Bangladesh. This study reveals the clay mineral composition of top soils of seven different soil series viz. Binsara, Taras, Jaonia, Hasnabad, Laskara, Manda and Mainam developed in the basin. X-ray diffraction (XRD) technique was employed to identify and quantify the minerals. Results show that mica (41 to 59%) was the most dominant mineral among all soils except Laskara. In Laskara soils, the interstratified mica-vermiculite-smectite (41%) was the predominant mineral. Next to mica, kaolinite (10 to 12%) was found to be present in the Binsara, Taras 1, Jaonia, and Taras 2 soils. Chlorite (7 to 17%) was identified in all the soils and was found to be the second dominant mineral in the Manda and Mainam soils. In contrast, the interstratified mica-vermiculitesmectite (33%) was found to be the second dominant mineral in the Hasnabad soils. Small amounts of vermiculite mineral (1 to 13%) were identified in almost all the soils except Binsara. All the soils have interstratified mica-chlorite minerals (2 to 7%). A tiny amount of smectite (1%) was identified in Taras 1 soil. As far as the clay mineralogical composition is concerned, most studied soils were found at the initial stage of weathering, indicating the high potential to sustain low input subsistence agriculture.&#x0D; Dhaka Univ. J. Biol. Sci. 30(2): 293-306, 2021 (July)

Soils and soil organic matter transformations during the two years after a low-intensity surface fire (Subpolar Ural, Russia)

With an rise in temperature in the circumpolar region, an increase in the frequency of fires can be expected. We studied the effects of fire in larch (Lárix sibírica Lebed.) forests on the organic matter composition of topsoils of Leptosols in the Subpolar Ural Mountains (northern taiga, Komi Republic, Russian Federation). We compared topsoils before the fire (BF), during the low-intensity surface fire (DF), one (1AF) and two years (2AF) after the fire. The low intensity surface fire burnt only the upper part of the organic horizon, leading to the formation of a thin pyrogenic horizon. The soil alteration included alkalization of the solution by three pH units, threefold increase in the content of exchangeable forms of cations, a nine times increase in the specific surface area of the solid phase, increase in total carbon and nitrogen contents, and a five-fold increase in the aromaticity of the organic matter. The latter is mirrored by a strong increase in benzene polycarboxylic acids (BPCAs) as marker for pyrogenic carbon (PyC), representing 82 to 97 mg BPCA C g-1C. Two years after the fire, arrival of fresh litter, intensified water regime and soil acidification led to a decline of the surface area of organic horizons. Thus, it was revealed that two years after a low-intensity fire, the soils differed from the initial ones in a total carbon and nitrogen contents, the organic matter aromaticity and the BPCA contents. The content of aromatic fragments in pyrogenic horizon evaluated according 13C NMR spectroscopy decreased after two years after fire, but at the same time, the PyC concentration, estimated on the carbon of BPCAs, remains stable. This indicates that periodically repeating low-intensity fires in boreal northern forests can contribute to the accumulation of stable forms of PyC in soils.

The effect of planting media composition and provision of liquid organic fertilizer on the growth of Casuarina junghuhniana seedlings

The purposes of this study were to determine the effect of planting media composition and liquid organic fertilizer concentration as well as their interactions on the growth and quality of Casuarina junghuhniana seedlings. The experimental design used a completely randomized design (CRD) factorial experiment with five replications. The first factor was the planting media with the composition of topsoil (control), topsoil:sand:husk charcoal (1:1:1), topsoil:sand:husk charcoal (1:2:1), topsoil:sand:husk charcoal (1:1:2), topsoil:sand:husk charcoal (2:1:1). The second factor was liquid organic fertilizer with a concentration of 0 ml (control), 100 ml/10 liters of water, 200 ml/10 liters of water, 300 ml/10 liters of water, 400 ml/10 liters of water. Growth variables observed were height, trunk diameter, number of leaves, top root ratio, and seedling quality index. Then, data were analyzed with the HSD at a 5% confidence level. The results showed that the treatment of planting media combination with topsoil:sand:husk charcoal (2:1:1) and liquid organic fertilizer concentration of 400 ml/10 liters of water had the best responses.

Altitudinal variations in the bulk organic carbon isotopic composition of topsoil in the Qilian Mountains area, NE Tibetan Plateau, and its environmental significance

Understanding the bulk organic carbon isotopic composition (δ13Corg) of the surface soil in various climates is crucial for past climate reconstruction. Although the relationship between climatic factors (such as precipitation and temperature) and plant δ13Corg are well studied at the global and regional scales, studies relating the surface soil organic matter δ13Corg values and climatic factors remain relatively rare. In this study, 52 surface soil samples were collected from the Shiyang River drainage basin, the northeastern margin of the Tibetan Plateau, where changes in vegetation are sensitive to the climate. The δ13Corg of the surface soils was analyzed to examine their environmental implications. Our results show that soil δ13Corg values change from −26.58‰ to −21.73‰ with an average of −25.20‰ (±1.14‰). Binary regression analysis and linear regression analysis show that the change in the soil δ13Corg values is significantly correlated with altitude; temperature and precipitation are responsible for the altitudinal impact on the soil δ13Corg while air CO2 concentrations have little effect. The sensitivity of the δ13Corg values to the mean annual temperature is +0.066‰/°C and to the mean annual precipitation is −0.3‰/100 mm. We find that extremely low temperatures (above 2960 m a.s.l. in the study area) may result in physiological drought in plants even when precipitation is favorable, which consequently leads to higher soil δ13Corg values. This observation is inconsistent with its direct positive role in the δ13Corg values below 2960 m a.s.l., and the threshold is −1.2 °C in the Shiyang River drainage basin. In addition, the slope of the regression line for the soil δ13Corg values versus altitude with favorable precipitation in our study is +1.2‰/km, which supports that a relationship of +1.1–1.3‰/km for the soil δ13Corg values versus altitude is available on the Tibetan Plateau and the surrounding areas and further indicates that this coefficient in this region maybe potentially be useful for paleoelevation reconstruction.

Measuring the change under compositional data analysis (CoDA): Insight on the dynamics of geochemical systems

Geochemical systems are complex and the analysis of the shape of the frequency distribution of elements and chemical species often informs about the variability and dispersion related to the underlying dynamics. However, when compositional data are used it is incorrect to investigate concentrations in the Euclidean space. Distribution analysis is aimed at focusing on real coordinates, which can be obtained by applying some appropriate log-ratio transformation. In particular, distributional analysis for compositional data can be applied to isometric coordinates, called balances, obtained through partition of a multi-element data set. As an alternative the same investigation can be performed on indices such as the robust Mahalanobis distance after having ranked log-ratio compositions with respect to some reference composition (i.e. average Earth crust) and having obtained a sort of “measure of change”. By considering this second new perspective, the chemical composition of topsoils of the Campania Region (Southern Italy) was investigated by analysing the concentrations of Al, As, B, Ba, Ca, Co, Cr, Cu, Fe, K, La, Mg, Mn, Mo, Na, Ni, P, Pb, Sr, Th, Ti, V and Zn, in mg/kg, determined on >3500 samples. Results reveal the presence of complex processes governed by interaction-dominant dynamics where self-organisation appears to play some role.

Compositional analysis of topsoil metals and its associations with cancer mortality using spatial misaligned data

The presence of toxic metals in soil per se, and in soil impacted by mining, industry, agriculture and urbanisation in particular, is a major concern for both human health and ecotoxicology. The dual aim of this study was: to ascertain whether topsoil composition could influence the spatial distribution of mortality due to different types of cancer and to identify possible errors committed by epidemiological studies which analyse soil composition data as a closed number system. We conducted an ecological cancer mortality study, covering 861,440 cancer deaths (27 cancer sites) in 7917 Spanish mainland towns, from 1999 to 2008. Topsoil levels of Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined by ICP-MS at 13,317 sampling points. We transformed the topsoil data in two ways, i.e. log transformation and centred logratio transformation. Principal factor analysis was performed to obtain independent latent factors for the transformed variables. To estimate the effect on mortality of topsoil factor loadings, we fitted Besag, York and Mollié models embedded in geostatistical-spatial models. This model included soil sample locations and town centroids (non-aligned data), fitted using the integrated nested Laplace approximation (INLA) as a tool for Bayesian inference and stochastic partial differential equations (SPDE). All results were adjusted for socio-demographic variables. The results indicated that soil composition could have an influence on the spatial distribution and mortality patterns of cancer. The analysis adjusted for socio-demographic variables showed excess male mortality due to digestive system tumours in areas with soils containing higher Cd, Pb, Zn, Mn and Cu concentrations, bladder cancer in areas with soils containing higher Cd concentrations, and brain cancer in areas with soils containing As. In both sexes, cancer of oesophagus was associated with soils containing a higher lead content, while lung cancer was associated with soils containing a higher copper content. Stress should be laid on the importance of taking into account the compositional nature of the data in this type of analysis.

Association between heavy metal and metalloid levels in topsoil and cancer mortality in Spain

Spatio-temporal cancer mortality studies in Spain have revealed patterns for some tumours which display a distribution that is similar across the sexes and persists over time. Such characteristics would be common to tumours that shared risk factors, including the geochemical composition of the soil. The aim of this study was to assess the possible association between heavy metal and metalloid levels in topsoil (upper soil horizon) and cancer mortality in mainland Spain. Ecological cancer mortality study at a municipal level, covering 861,440 cancer deaths (27 different tumour locations) in 7917 Spanish mainland towns, from 1999 to 2008. The elements included in this analysis were Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Topsoil levels (partial extraction) were determined by ICP-MS at 13,317 sampling points. For the analysis, the data on the topsoil composition have been transformed by the centred logratio (clr-transformation). Principal factor analysis was performed to obtain independent latent factors for the transformed variables. To estimate the effect of heavy metal levels in topsoil composition on mortality, we fitted Besag, York and Mollié models, which included each town’s factor scores as the explanatory variable. Integrated Nested Laplace Approximation (INLA) was used as a tool for Bayesian inference. All results were adjusted for sociodemographic variables. The results showed an association between trace contents of heavy metals and metalloids in topsoil and mortality due to tumours of the digestive system in mainland Spain. This association was observed in both sexes, something that would support the hypothesis that the incorporation of heavy metals into the trophic chain might be playing a role in the aetiology of some types of cancer. Topsoil composition and the presence of potentially toxic elements in trace concentrations might be an additional component in the aetiology of some types of cancer, and go some way to determine the ensuing geographic differences in mortality in Spain. The results support the interest of inclusion of heavy metal levels in topsoil as a hypothesis in analytical epidemiological studies using biological markers of exposure to heavy metals and metalloids.

Soil geochemistry changes induced by a foreign soil reconstruction project in Three Gorges Reservoir region of China

Fertile topsoil was added onto the surface of barren slope land in Three Gorges Reservoir region of China in an anthropogenic process known as the foreign soil reconstruction project. The main goal of this paper was to reveal the influence of anthropogenic activities on pedogenic processes and soil classifications. Chemical weathering indices and comparative analysis were applied to discuss changes in geochemical compositions and weathering features of purplish soils (Cambisols) before and after the project. Results showed that: (1) The foreign soil reconstruction project slightly altered the major element composition of topsoil and improved the soil structure. Although the distributions of major elements in the original topsoil, original subsoil, foreign topsoil and newly constructed topsoil were all similar to that in upper continental crust, newly constructed topsoil was the most similar soil. (2) The chemical index of alteration was more sensitive than the weathering index of Parker at indicating chemical weathering status of purplish soil. The chemical weathering status of newly constructed topsoil was higher than that of the original topsoil and lower than that of foreign topsoil. (3) Anthropogenic activities may provide a promising new thought for the anthropogenic soil classification system. The scope and subgroups of Anthrosols should be extended and strengthened. Or there may be a need to combine Anthrosols and Technosols orders to create a new soil order. The results may be used for optimizing soil mellowing engineering activities and enriching the soil classification system.

Chemotaxonomy and diagenesis of aliphatic hydrocarbons in rice plants and soils from land reclamation areas in the Zhejiang Province, China

Rice is the most important staple food globally and requires large growth areas kept under flooded paddy conditions, contributing significantly to microbial greenhouse gas emissions. Biogeochemical cycling in such agroecosystems has been investigated intensively but molecular biomarker studies are scarce. We conducted a chemotaxonomic investigation of wax alkanes differentiated for plant tissue (leaf, stem, root) of rice and intercrop plants (maize, sorghum, rape, mustard, bean, cotton) and studied the incorporation of these lipids into soil under paddy compared with upland management forms. Soil chronosequences reflecting paddy and upland agroecosystem changes compared with natural soil substrates over the past two millennia were studied in land reclamation areas of Zhejiang Province, China. Soils evolved on tidal wetland sediments contained predominantly lipids derived from terrigenous supply by the Yangtze River (YR=Chang Jiang) and to a lesser extent from marine sources via the East China Sea (ECS). Agricultural usage converted lipid composition of topsoil within 50yr to reflect the n-alkane patterns of crops with their relative proportion increasing with cultivation time. Alkyl chain length distribution of rice was broad compared with upland plants, due to the water regime changing over the growth period. This separated paddy from upland managed soils on the basis of alkyl lipids, allowing reconstruction of past land use change. Combustion of crop biomass after harvest is common practice and generates alkenes upon incomplete combustion which, due to their high reactivity, are immediately converted to alkanes with lower carbon preference index (CPI) in topsoil. The storage of lipids and organic matter over time is greater in paddy than in upland managed agroecosystems and contributes to CO2 sequestration from the atmosphere.

Metals in soils of erosional systems in forest zone in the central part of European Russia

Small erosional landforms, despite their importance in mass transfer processes, have received insufficient attention in geochemical studies. This paper presents a case study dealing with geochemistry of two small erosional systems, typical of humid moraine landscapes of the central part of European Russia. They are considered as integrated systems comprising several units viz. slopes, bottoms, detrital fans as well as adjacent areas as sources of solid material. Chemical composition of topsoil (total concentrations of Ti, Zr, Mn, Co, Zn, Cu, Pb, Cr, V, Ni, Sn, Sr, Ba and concentrations of the acid-extractable Fe, Mn, Co, Zn, Cu, Pb, Cr, Ni) was used to explore the role of granulometry, pH, organic matter content and transport processes in geochemical differentiation of the systems. Spatial variations in granulometry across the various units indicate a progressive depletion of a finer material in the gully and comparatively invariant distribution of the same fractions within the balka. The granulometry is the main factor controlling the distribution of total and acid-extractable metal concentrations in both systems. The findings imply that the prevailing mechanism of metal migration through the studied systems is a suspension transfer in association with clay and silt particles. The young gully system operates as a transit system and shows higher geochemical differentiation than the aged balka system where some elements may accumulate in topsoil of the lower units of this system.

Impact of flood deposits on earthworm communities in alder forests from a subalpine floodplain (Kandersteg, Switzerland)

In many ecosystems, bioindication is a tool to estimate biodiversity and quality of environment. In soils, invertebrates are generally suitable bioindicators, especially earthworms. In floodplains, young alluvial soils are exposed to sedimentation and erosion, and little is known about soil bioindication. Moreover, a reference state is now needed to evaluate river restoration projects. The aim of our study was thus to establish an “undisturbed” floodplain reference at the subalpine level based on earthworm communities and to test if they are indicators of fluvial dynamics. Seven plots were chosen along a stretch of the Kander River (BE, Switzerland). At each plot, a soil profile was described (carbonated Fluvisols) and topsoil was analysed. Earthworms were extracted in each plot using standard mustard extraction (3 × 1 m2) and “hand sorting” method (20 × 20 × 20 cm). Eight species were identified, and Lumbricus meliboeus was found for the first time in a carbonated environment. The absence of anecics was considered, at the subalpine level, as a bioindication of the fluvial dynamics (erosion and sedimentation processes). Biomass of epigeics was positively correlated to topsoil texture and organic matter quality, and thus epigeics, sensitive to variations of topsoil composition, are bioindicators of the latest flood event at the subalpine level.

Trace metal enrichment in sugarcane soils due to the long-term application of fertilisers, North Queensland, Australia: geochemical and Pb, Sr, and U isotopic compositions

This study aimed to determine whether &gt;80 years of fertiliser application has led to recognisable changes in the trace metal (Cd, Cu, Mo, Ni, Pb, Sr, Th, U, Zn) chemistry of topsoils (0–0.10 m) from sugarcane land, northern Queensland, Australia. The metal concentrations of commercial nitrogen (N) and potassium (K) fertilisers currently used in northern Queensland were generally lower than those of phosphate fertilisers and fertiliser blends. Composite topsoil samples (0–0.10 m depth) taken from canelands had higher median Cd, Mo, Pb, Sr, Th, U, and Zn concentrations than topsoils from forested areas of the catchment. Niobium, Ta, and Ti were confirmed as refractory immobile elements and used as reference elements for the evaluation of trace metal enrichments. Bivariate plots of trace metal/immobile element ratios verified that Cd, Mo, Pb, Sr, Th, U, and Zn are enriched in sugarcane soils compared with background forest soils. Isotopic ratios for Pb, Sr, and U highlight that fertilisers, cane soils, and forest soils have isotopically distinct compositions. Phosphate fertilisers currently used in the agricultural industry possess the most radiogenic 87Sr/86Sr, 234U/238U, 207Pb/206Pb, and 208Pb/206Pb ratios. Background forest soils have the highest 87Sr/86Sr, 207Pb/206Pb, and 208Pb/206Pb and lowest 234U/238U ratios. By contrast, cane soils exhibit 207Pb/206Pb and 208Pb/206Pb ratios that appear on a mixing line between the isotopically distinct background soils and phosphate fertilisers. Also, cane soils possess 234U/238U ratios similar to phosphate fertilisers. Thus, the application of phosphate fertilisers to canelands has resulted in higher Cd, Mo, Pb, Sr, Th, U, and Zn concentrations and more radiogenic Pb, Sr, and U isotope ratios in cane soils. Trace metal ratios and the Pb, Sr, and U isotopic composition of topsoils and fertilisers are useful tools to recognise fertiliser-derived trace metals in agricultural landscapes.

Development of topsoil grain size index for monitoring desertification in arid land using remote sensing

The grain size composition of topsoil characterizes the soil texture and other physical properties. The coarsening of topsoil grain size is a visible symbol of land degradation; thereby the change in topsoil grain size can be potentially used to monitor desertification using remote sensing. This study proposes a new index for detecting topsoil grain size composition through ground in situ soil spectral reflectance measurements and soil physical analysis in the laboratory. The proposed topsoil grain size index (GSI), which has a positive correlation with fine sand content, was then applied to detect desertification in Siziwang Banner, Inner Mongolia, China, using a Landsat TM (1993) image and a Landsat ETM+ image (2000). The result shows the fine sand content of topsoil increased in most places, indicating a coarsening process of the topsoil in the study area. The fast soil coarsening of degradation is largely caused by human activities.