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The identification of the spatial distribution of soil trace-elements and the contribution of different sources to the sediment yield is necessary for a better watershed and river water quality management. Until now, less attention has been paid to comprehensive assessments of sediment sources and soil trace-elements with respect to the suspended sediment production. The present study aimed at modelling the spatial distribution of soil trace-elements, quantifying the sediment sources apportionment and relating the landforms to polluted soils. Different techniques and approaches such as the Nemerow pollution index, machine learning algorithms (Random Forest (RF), generalised boosting methods (GBM), generalised linear models (GLM) and sediment fingerprinting were applied to the Kan watershed. A total of 79 soil samples having different Nemerow index values were considered for spatial modelling. Using statistical methods (Range test, Kruskal-Wallis and discrimination function analysis), an optimal set of tracers was selected. An unmixing model was applied to calculate the relative contribution of landforms for eight rainfall events. The results of the soil trace-element mapping showed that RF had the best performance with an accuracy of 83%. The evaluation of polluted soil areas showed that the landforms 'steep hills' and 'valley' contributed the most with 51% and 27% in the riparian zone, respectively. In addition, these landforms give a high contribution to sediment production in late-winter-spring events (29%) with a GOF (goodness of fit) of 0.65. The landform 'plain' had the highest contribution (28%) in sediment yield with a GOF of 0.72 in early-winter events. This means that the valley and steep hill landforms accelerate the transport of trace-elements across the watershed. Interestingly, the contribution of landforms varies during the year. Overall, the new proposed approach enables to better trace the origin of suspended sediments and trace-elements discharge into the river environment.

Vast areas in the Mediterranean are characterised by evaporite deposits of the Messinian crises (c. 6–5.3 Ma BP). During this period, large deposits were built up in shallow lagoon-like systems and are now found in southern Italy, Albania, Cyprus and Turkey. So far, soil formation on evaporites has been studied predominantly in subarid to arid environments. Although the formation of soils has received new significance, little is known about the evolutional trajectories on evaporites of the Mediterranean. We therefore studied soil formation in the Caltanissetta basin (Sicily) where evaporites are most widespread. The lithologies included the sequence: marine clay deposits, laminated marl (diatomite; Tripoli sediments), Calcare di Base (limestone), detritic deposits, gypsum (selenite). The chemical signature (immobile elements, rare earth elements) indicated that they all have a similar origin. Surprisingly, both an increasing Corg and carbonate content in the soils caused a decrease in the δ 13C signal in carbonates and in part in the bulk soil. The low δ 13C and δ 18O values of carbonates in the parent material indicate a high rock-water (or meteoric water) interaction that has occurred during sedimentation and diagenesis. Organic matter was oxidised into the shallow lagoon-like systems and its carbon incorporated in the limestone. Elemental leaching from silicates during pedogenesis was most intense in the soils that developed on clays and Tripoli sediments. Vertisols and Mollisols have evolved, together with a high amount of oxyhydroxides (non-crystalline and crystalline forms) and kaolinite. Only weak soil formation was recognisable at sites having gypsiferous parent material. The presence of a high amount of selenite hindered a more advanced evolution. The soils developed on detritic and gypsiferous material exhibited some palygorskite that was inherited from the parent material. At sites having selenite or limestone, shallow Aridisols or Mollisols are found. Weathering is weakly pronounced, e.g. indicated by a high proportion of trioctahedral minerals. Besides inheritance from the parent material, smectite and kaolinite are also actively formed in the soils with increasing weathering. Plagioclase and mica are the main sources of smectite and K-feldspar is a main source of kaolinite neo-formation. The evaporite deposits vary greatly within short distances causing a high spatial diversity of soils. Consequently, soil quality strongly varies, which challenges agricultural use. Well-developed soil profiles and advanced weathering stages are only possible when marine clays, Tripoli sediments or detritic deposits are the parent material. Limestone (Calcare di Base) and gypsiferous sediments (selenite) strongly limit soil formation and mineral transformation.

Recent studies have demonstrated that soils formed on pyroclastic ash deposits are much more common in the Mediterranean area than previously assumed. These soils are an important key to understanding past volcanic events and landscape evolution. Chronological information in soils of Quaternary volcanic events, however, remains still poorly understood in southern Italy. Using a multi-method forensic approach, we explore the origin and age of volcanic deposits (soils) in Sicily and Calabria. The geochemical signature of the soil was compared to the chemical fingerprint of the magmas of potential source areas of southern Italian volcanoes. The results indicate that the investigated soils on the Nebrodi (Sicily) and Sila (Calabria) mountains were both impacted by materials having a high-K calc-alkaline series volcanism. The Aeolian Islands (in particular Lipari and Vulcano) are the most likely source of origin, but contributions also from the Etna (particularly the Biancavilla ignimbrites and Plinian eruptions) occurred. Weathering and leaching processes, along with a potential contribution from the underlying non-volcanic bedrock, has altered the main chemical composition of soils, often precluding direct relation to potential source areas. Immobile elements and their ratios (e.g. the Nb/Y vs Zr/Ti plot) or trace elements (Co, Th) and rare earth elements (laser ablation ICP-MS analyses of glass particles, volcanic clasts and pumice-like materials) gave precious hints of the origin of the volcanic deposits. Radiocarbon dating of the H2O2 resistant soil organic fraction indicates a minimum age of 8–10 ka of the soils. The weathering index WIP (weathering index according to Parker) and the chemical composition of volcanic glasses and clasts were tested as proxies for the age of the volcanic deposits and time for soil formation. The soils and landscape are characterised by multiple volcanic depositional phases for the last about 50 ka in the Sila mountains and about 70 ka or more in the Nebrodi mountains. Chemical-mineralogical analyses enabled the detection of deposition phases during the Pleistocene and also Holocene. The multi-method approach enabled the identification of potential source areas, provided a tentative age estimate of the start (and in part duration) of ash deposits and therefore improved our understanding of volcanic landscape evolution.

Deadwood is known to significantly contribute to global terrestrial carbon stocks and carbon cycling, but its decay dynamics are still not thoroughly understood. Although the chemistry of deadwood has been studied as a function of decay stage in temperate to subalpine environments, it has generally not been related to time. We therefore studied the decay (mass of deadwood, cellulose and lignin) of equal-sized blocks of Picea abies wood in soil-mesocosms over two years in the Italian Alps. The 8 sites selected were along an altitudinal sequence, reflecting different climate zones. In addition, the effect of exposure (north- and south-facing slopes) was taken into account. The decay dynamics of the mass of deadwood, cellulose and lignin were related to soil parameters (pH, soil texture, moisture, temperature) and climatic data. The decay rate constants of Picea abies deadwood were low (on average between 0.039 and 0.040y(-1)) and of lignin close to zero (or not detectable), while cellulose reacted much faster with average decay rate constants between 0.110 and 0.117y(-1). Our field experiments showed that local scale factors, such as soil parameters and topographic properties, influenced the decay process: higher soil moisture and clay content along with a lower pH seemed to accelerate wood decay. Interestingly, air temperature negatively correlated with decay rates or positively with the amount of wood components on south-facing sites. It exerted its influence rather on moisture availability, i.e. the lower the temperature the higher the moisture availability. Topographic features were also relevant with generally slower decay processes on south-facing sites than on north-facing sites owing to the drier conditions, the higher pH and the lower weathering state of the soils (less clay minerals). This study highlights the importance of a multifactorial consideration of edaphic parameters to unravel the complex dynamics of initial wood decay.

At mid-latitudes, the transition from the Pleistocene to the Holocene was characterised by distinct and partially abrupt climatic changes. Also during the Holocene, climatic perturbations, with sometimes cold-dry conditions, have occurred. How land surfaces and soil development processes in high-mountains respond to these climatic oscillations is so far only poorly known. We traced the responses of surfaces in the alpine settings of the Wind River Range (Wyoming, US) by using a large mire as natural archive. This enabled us to reconstruct environmental conditions and ecosystem changes during the Holocene in this montane area. Although adjacent moraine deposits display 10Be exposure ages from the Last Glacial Maximum up to MIS16 or even older, the accessible sediment deposits covered only the Holocene (via radiocarbon dating). By applying a geoforensic approach and deriving sedimentation rates, major climatic signals were detected. A higher deposition (and consequently erosion) rate and thus a higher rate of geomorphic activity was measured for the known cold periods 9.4–10.2 ka BP, 4.2 ka BP and 2.5 ka BP. During the LIA, especially rapid aggradation of organic matter organic matter took place here. Rates of chemical weathering and soil formation seem to have been relatively low until about 5–6 ka BP but have since increased during the Late Holocene. This would fit previous observations of increasing moisture conditions after the mid-Holocene aridity period. In contrast to several other studies, no clear signs of major disturbances (erosion, weathering) during the 8.2 ka event could be observed. Together with the low levels of chemical weathering found here, we do not see any evidence that the climate was more humid during this period. Compared to previous findings, more humid conditions seemed to have returned earlier, i.e. about 5 kyr BP. In general, this landscape displayed a patchy pattern of reaction to environmental changes, as all events were not recorded in each mire profile., Geomorphology, 371, ISSN:0169-555x, ISSN:1872-695X

Purpose: The present work focuses on cold alpine soils of the Altai Mountains (Siberia, Russia). Permafrost is widespread and often occurs at a depth of about 100cm. The area is characterised by extremely cold winters and cool summers: the aim was consequently to find out whether weathering could be more intense on thermally less unfavoured conditions or whether the abundance of water could be a more important factor. Materials and methods: We investigated 10 soils in a very small area close to a local glacier tongue. Five of the investigated soils were south-facing and the other five north-facing. The soils have the same parent material (mica-rich till), altitude, topography and soil age. The vegetation is alpine grassland that is partially intersected with some juniper and mosses. Soil chemical properties such as organic C, N, soil organic matter quality (using DRIFT), pH value, (oxy)hydroxides, total elemental contents (XRF) and soil micromorphology and mineralogy (using diagnostic treatments and XRD) were determined. The age constraint of the site was given by geomorphic studies together with 14C dating of a nearby peat bog and the stable organic matter fraction of the soils. Results and discussion: The soils have a Holocene age. The results showed astonishingly clearly—similarly to the European Alps—that the north-facing soils have a higher weathering state. This is expressed by lower pH values, higher oxalate and dithionite extractable Fe, Al, Mn and Si contents, higher C and N concentrations and stocks when compared to the south-facing sites. No statistically significant differences with respect to weathering indexes could be detected. The geochemical evolution of the soils seems to be enhanced at north-facing sites, even though very severe climatic conditions prevail. Furthermore, biodegradation seems to be less pronounced on north-facing compared to south-facing sites as poorly degraded organic matter is accumulated. This gives rise to more organic ligands that promote metal binding and their subsequent eluviation along the soil profile. Conclusions: We consequently must assume that weathering is not limited by low temperatures in the active layer but is rather controlled by soil moisture that seems to be higher during the warmer period in the north-facing soils.

The aim of this work was to detect imprints on soil properties from former Islamic land use (9th to 11th century) using a multi-method, soil-chemical approach. Four soil profiles (with buried horizons) found in the vicinities of former Islamic settlements in Sicily were analysed for phosphorus (total, organic and inorganic), nitrogen (total, NO 3 − and NH 4 + ), carbon compounds (δ 13 C, lipids, polycyclic aromatic hydrocarbons (PAH) and functional groups), physical and chemical C-fractions and the state of soil weathering. Two soil profiles contained ceramic sherds from the Islamic period. Inorganic nitrogen forms, phosphorous and the PAH content indicated strong impacts from traditional agriculture and/or burning. Radiocarbon dating of soil organic carbon (SOC) fractions from buried horizons showed that distinct changes must have occurred during the Islamic epoch. The isotopic composition of SOC indicated that land use was probably different in earlier times. C 4 plant cultivation was expected but surprisingly lipid analyses did not confirm this. A high amount of aliphates and low C/N ratio indicated a good, long-term SOC stabilisation under the native conditions combined with Islamic land use. The irrigation of the soils probably increased the production of weakly-crystalline Fe forms that helped to stabilise SOC. The multi-method approach was very helpful in deciphering human-induced processes. Although a full proof for each parameter is not given, former Islamic land-use seems to have distinctly affected the soils – not only locally but probably also in other areas of Sicily, Northern Africa, Near East and Iberian Peninsula.

Using published and new chronosequence datasets from the European Alps and the Wind River Range (Rocky Mountains, USA), we report for the first time a chronosequence of more than 1 Ma for soil organic carbon, nitrogen and organic matter (SOM) fractions from alpine soils. The investigated parameters include total carbon and nitrogen as well as the stable (resistant to H2O2 oxidation) C and N fractions. Time trends were analysed and are reported on the basis of stocks and concentrations. The accumulation rates of C and N strongly decreased with increasing soil age. Differences in trends between the European Alps and the Wind River Range might be attributed to the factor climate. For the drier Wind River Range, an asymptotic value of about 15 kg C m− 2 was reached after about 15 ky while an asymptotic value of 20–25 kg C m− 2 was measured for the moister European Alps after about 3 ky. The difference in N stocks between the two regions was less obvious. For both areas, N was in the range of 0.5–2 kg N m− 2. Using the exponential decay model, a steady state of C and N (stable and total) concentrations in the topsoil seemed to be reached after < 1 ky (Alps) and 10 ky (Wind River Range). The retardation effect observed for the Wind River Range could probably be due to aeolian influx. For both areas, the asymptotic value of the stable fraction of C and N was in the range of 1–3 kg C m− 2 and 0.2–0.4 kg N m− 2, respectively. The stable organic fraction often has an age close to the age of the soils and consequently can reach thousands of years. The relative proportion of N and amides was higher in the stable organic fraction compared to the bulk soil. The sequestration rates of org. C and N in soils of the European Alps and the Wind River Range can reach very high values in very young soils whereas in old soils sequestration rates are several orders of magnitude lower. Old soils often integrate several cold and warm phases and different vegetation types. Nonetheless, the factor Time seems to be very dominant and covers the track of other factors in old soils.

In this study we compare newly-developed chemical weathering data with previously published data from soils developed along two chronosequences of glacial deposits in the European Alps and the Rocky Mountains (Wind River Range, USA). By combining these chronosequences, we are able to present a comprehensive dataset that represents a time period of > 1 Ma. We describe weathering trends of important elements using a number of weathering indices (e.g., K + Ca/Ti ratio, the weathering ‘index B’ of Kronberg and Nesbitt (1981) and the open mass transport function). Further, we describe the accumulation of Al, Fe, Si and Mn oxyhydroxides (including partially organic phases) as a function of time, and derive the corresponding accumulation rates. We calculated pedogenetically formed oxyhydroxides using an approach based on immobile elements. Our study represents one of only a few studies that describe rates of soil chemical weathering over a period as long as ~ 1 Ma. Results show that rates of chemical weathering clearly decrease along the chronosequences with increasing age of the soils. We find weathering rates are nearly four orders of magnitude lower in the 1 Ma-old soils than in the young soils. Our results suggest that the older soils may be reaching a steady state for these chemical properties in their present environments. A power function best explains the measured time-trends of the ‘index B’ and (K + Ca)/Ti) ratios in the soils. The best time-trend model for pedogenic weakly- to poorly crystalline phases and the relative losses/gains (based on the open-system mass transport function) were obtained with an exponential decay model function. In terms of the soil system, the decreases in the accumulation rate of the oxyhydroxides appears to be influenced not only by the factor of time but by climate as well (increased precipitation at higher altitudes slows the decrease in weathering rate over time). Thus, our ~ 1 Ma chronosequences also become pedogenic gradients since we describe variations in soil properties along biogenic gradients.

In recent decades laurophylloid vegetation has started to colonise forests of southern Switzerland and northern Italy. The increased colonisation since about 1950 is due to increased winter temperatures and urbanisation. With respect to the changes in the vegetation cover, the question arises as to whether or to which extent they influence soil organic matter quality and chemistry. In southern Switzerland, the common forest vegetation at sites bc. 1000 m a.s.l. consists predominantly of chestnut species (Castanea sativa) that have been introduced approx. 2000–3000 years ago. An older vegetation type, however, would be a Quercetum– Betuletum forest that can still occasionally be found in the area Locarno/Ascona/Cannobio. We studied the short-term influence of the laurophylloid vegetation and also the long-term influence of chestnut on soil characteristics including total organic carbon and nitrogen, pH, CEC, soil lightness and chemical fractions of soil organic matter. The characterisation of the functional groups of fulvic and humic acids was performed using IR-spectroscopy. In general, short-term differences in the C/N ratio and also in the quality and quantity of fulvic and humic acids seem to be likely between laurophyllous and chestnut stands. In general, lower C/N ratios and fulvic and humic acid contents were measured in soils under laurophyllous species. The laurophylloid vegetation gave rise to higher percentages of proteic amides, aliphatic CH₂ and CH₃ and lower C=O amide groups in the fulvic acids. A trend towards a lower humification degree was measurable for the sites with laurophylloid vegetation where organic matter seems to be less resistant to biodegradation. A significant effect of the laurophylloid vegetation on the org. C concentration was, however, not detectable. Chestnut very probably influenced soil organic matter in the long-term by producing lower total C and N contents, by a decrease in soil darkness, a lower amount of humic acids and a decreased CEC as compared to the older Quercetum–Betuletum vegetation. The differences in humus chemistry between chestnut and Quercetum–Betuletum stands were, however, small because the quality of the litter source seems to be similar. The colonisation of laurophyllous species is an obvious indication of human impact and of fast and accelerating climate change that after a few decades already led to a remarkable influence on soil and humus chemistry.

Soil sterilisation with steam under pressure and additives, such as CaO or KOH that react exothermically in water, is an alternative technology to fumigants. The influence of soil sterilisation (system ‘Bioflash’, Ecoflash SC 600) on the chemical behaviour of organic matter, heavy metals (Cd, Cu, Zn and Pb) and clay mineralogy was investigated on three typical soil materials (Ap horizons) with different carbonate contents. These materials were treated in the laboratory in wooden containers. Soil heating produced temperatures ranging between 60–80 °C for at least 20 min. The treatment generally seemed to increase the pH values and may lead in the long-term to a certain alkalisation with high dosages of CaO or KOH. The effects of the CaO treatment on the K and Ca speciation in the soil were rather small, whereas those of the KOH treatment were more pronounced for K. The addition of KOH favoured the fixation of K in the interlayers of smectite. The XRD measurements were in agreement with the chemical speciation of K. The K chemistry was affected by the treatment by higher contents of the fixed fraction. Organic matter partially decreased after the soil heating treatment. The behaviour of the heavy metals was also affected. In some cases, the EDTA-extractable fractions of Cu, Zn or Pb as well as the soluble fractions of Cu and Zn were distinctly changed after the treatment. The soil-heating treatment probably affected the type and amount of organic ligands and also the adsorbing surfaces that control the solubility of the heavy metals. The heavy metal solubility, however, still remained low after the treatment. The effects of the soil sterilisation on the chemical and mineralogical properties did not seem to be dramatic. It is, however, difficult to predict possible changes if the treatment is repeated over years to decades. We presume that there might be quite substantial effects (especially on the behaviour of organic matter under certain circumstances) in the long term if, as seen at some sites, changes (i.e. decrease) are already measurable after one treatment. Mulching or the addition of organic manure would be possible measures to counter a destabilisation of the soil (i.e. increase in soil erosion susceptibility) and a continuous disintegration of the organic matter pool.