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Ikaite formation and its transformation to calcite occurs via distinct amorphous calcium carbonates (referred to as I and II) that differ in their morphology, particle size, water content and stability.

Ikaite (CaCO3*6H2O) is a cryogenic calcium carbonate phase, which forms below about 5°C. If the temperature increases above 5-7 °C ikaite transforms to calcite. Understanding the transformation process is important to interpret paleoclimatological data from glendonites, i.e., calcite pseudomorphs after ikaite in sediments. Tollefsen et al. (2020) suggested that the transformation occurs via a coupled dissolution–reprecipitation mechanism at the ikaite–calcite interface (1). In contrast, Vickers et al. (2022) proposed a quasi-solid state ikaite to calcite transformation mechanismand suggested that stable isotope data of glendonite can be used for reconstructing paleotemperatures(2). However, in sediments the majority of the ikaite to calcite transformation occurs in diagenetic environments, where ambient solutions interact with the transforming mineral.We synthesized ikaite at 2 °C in alkaline environment in order to study its transformation using organic solvents, vacuum pumping and rapid (1 min) heating from 5 to 30 °C. These experiments indicated the formation of amorphous calcium carbonate (ACC) during the ikaite to calcite transition. We also monitored the ikaite transformation by letting the 2 °C parent solution to reach room temperature (25 °C) within ~5 hours. We observed ACC and calcite formations depending on the alkalinity of the parent solution. Our experiments suggest that the ikaite to calcite transition is a two-step process consisting of the solid-state ikaite → ACC transformation and the ACC → calcite dissolution–reprecipitation mechanisms. During these transitions ikaite lost all its water but preserved its original morphology. We hypothesize that the occurrence of a transient amorphous phase during the ikaite to calcite transition implies the alteration of the isotopic data, similar to what was reported for the ACC to calcite transition (3).We acknowledge the financial support of NKFIH ANN141894 grant. References:(1) E. Tollefsen, T. Balic-Zunic, C. M. Mörth, V. Brüchert, C. C. Lee and A. Skelton, Scientific Reports, 2020, 10, 8141.(2) M. L.Vickers, M. Vickers, R. E. M. Rickaby, H. Wu, S. M. Bernasconi, C. V. Ullmann, G. Bohrmann, R. F. Spielhagen, H. Kassens, B. P. Schultz, C. Alwmark, N. Thibault and C. Korte, Geochimica et Cosmochimica Acta, 2022, 334, 201-216.(3) A. Demény, Gy. Czuppon, Z. Kern, Sz. Leél-Őssy, A. Németh, M. Z. Szabó M. Tóth, C.-C. Wu, C.-C. Shen, M. Molnár, T. Németh, P. Németh and M. Óvári, Quaternary International, 2016, 415, 25-32.

Soil organic matter (SOM) is an essential fraction of soil and contributes to its fertility. Land use and cultivation may affect SOM. This study investigates whether SOM concentration and composition differ in soil pools or are changed by soil management (tillage, fertilisations, and crop covers). Soil samples were collected in April 2019 from cropland and nearby grassland. The study sites were part of a long-term experiment in Martonvasar (Hungary), established in 1958 and characterised by Chernozem soils. Total organic carbon (TOC) contents and compounds were studied in three soil pools (bulk soil, fast pool, and slow pool). Both TOC and total N concentrations were high in the slow pool, with higher stored C contents in grassland than in cropland. Tillage effects reduced aggregate stability in cropland, which explains a lower aliphatic content than grassland. Insufficient physical protection due to the tillage practice may enhance OM loss in cropland even under fertiliser inputs. Neither fertiliser nor crop covers affected SOM compositions, while they were different in soil pools. More complex OM in the slow pool than in the fast pool. It indicates that the slow pool is the main protecting path for SOM, possibly referred to older or decayed organic compounds. To understand the bottom-up process, microorganisms’ community role in SOM stabilisation needs to be studied.

2005-ben Somogy megyében autóút építését megelőző nagyfelületű ásatáson, Balatonlelle határában két késő rézkori csontvázas sír került elő. Mindkét sírban az elhunyton kívül további koponyák maradványait is megtalálták. A 415. sírba temetett 8–9 éves gyermek csuklóján csaknem tiszta rézből készült pántkarperec, a nyakán szerves anyagból kialakított fekete, gagát jellegű gyöngy, és egy kalapált lemezgyöngy volt az edénymellékleteken kívül. A temetkezési mód és az analógia nélküli ékszermellékletek arra utalnak, hogy a sírba különleges státuszú gyereket temettek. A DNS elemzés rokonságot is ki tudott mutatni az elhunyt fiú és a sírjába tett egyes koponyamaradványok között. A fekete gyöngyöt kombinált optikai mikroszkópos, röntgenfluoreszcens spektroszkópos (XRF), pásztázó elektronmikroszkópos, Fourier transzformációs infravörös spektroszkópos (FTIR) és stabilizotóp-geokémiai vizsgálatoknak vetettük alá. A gyöngy könnyű, hálózatosan repedezett anyag, ami meglehetősen törékeny és a törési felület fényes, kagylós törést mutat. A belső szerkezet csiszolt felületen hosszúkás, irányított pórusokat mutat, a szénült fa szerkezetéhez hasonlóan. Az XRF elemzések a szilikátok alárendelt mennyiségét jelzik, így a szervesanyag-dús üledékes kőzet (pala) kizárható. A szakirodalomban gagátnak (angolul jet) nevezett minta FTIR spektruma jelentősen különbözik az ismert gagát/jet előfordulásokétól, viszont erősen hasonlít a karbon korú kőszenekhez, különösen a francia és spanyol előfordulásokhoz. A stabilhidrogén- és -szénizotóp- összetételek a leginkább a karbon korú szenekhez állnak közel, a helyi és a közeli regionális szenek, valamint a speciális képződési környezetet jelentő gagát (jet) előfordulások elvethetőek forrásanyagként. Az adatok együttesen legvalószínűbb forrásként a spanyol vagy francia karbon korú szenekre utalnak, mint potenciális forráskőzetre. Mindazonáltal további szisztematikus gyűjtés és elemzések szükségesek a „gagát” gyöngy eredetének feltárására.

A talajok szennyezőanyag-tartalmát leginkább az antropogén hatások befolyásolják, a nagyvárosokban elsősorban az építkezések, közúti forgalom, a nem megfelelő csatornázás, az esetleges csatornatörésekkor talajba kerülő különböző anyagok. Ezen anyagok elhelyezkedése, mozgása a talajban folyton változik, függ a szennyezés mértéke függ a felszíntől való távolságtól, a talaj összetételétől, a hatás mértékétől, a talaj vastagságától, a talajt alkotó ásványok összetételétől és azok arányától, stb. Tanulmányunkban Budapest XI. kerületének városi talajaiban lévő nehézfémtartalmat vizsgáztuk a talajok különböző kémiai és ásványtani tulajdonságai alapján. A munkánk során bizonyítást nyert, hogy az erős antropogén hatás alatt álló városi talajokban a határértékeket többszörösen meghaladó króm tartalom is előfordulhat, amely komoly aggodalomra adhat okot. A rendelkezésre álló adatok alapján kijelenhetjük, hogy a szennyező anyagok nem természetes eredetűek, minden esetben valamilyen emberi tevékenységre vezethetők vissza. A SEM-EDX mérésekből arra következhetünk, hogy a mért nehézfémek a talajokban elemhelyettesítésként vannak jelen, vagy egyes agyagásványokba épülve, illetve azok felületén dúsulhatnak.

Purpose Small-scale runoff and soil redistribution processes are important factors in rainfall simulation studies. Therefore, the main objective of this study is to examine the feasibility of rare earth oxide (REO) tracking combined with 3D surface modelling and soil crust analysis by scanning electron microscopy. Materials and methods Four 40 mmh−1 rainfall simulations (divided into two blocks) were conducted on a Luvisol sample at 9% slope steepness. In a block, two successive simulations were run on a tilled, and then, on a crusted surface. Before the first rainfall simulation of a block, the tilled surface was prepared by hoeing and application of four REO tracers (Pr6O11 Sm2O3, Ho2O3 and Yb2O3) to the freshly tilled surface. REOs divided the parcel into two back, and two front sub-parcels. The REO runoff content was measured by XRF, while the redistributed REOs were measured by SEM on polished crust samples taken after the second experiment in each block. Additionally, before and after 3D models of the surface were created for determining runoff direction and redistribution pattern. Results and discussion According to the REO content of the soil loss samples, the soil washed down from the front sub-parcels, while back parcels started contributing to soil loss only during the second block experiments. The surface microtopography changed between the experiments. The runoff path from the back sub-parcels headed to one side of the parcel. This strong, cross-side runoff pattern explained the lack of the back sub-parcel REOs in the soil loss. Meanwhile, in the crust samples, several forms of the redistribution were identified. The REOs of the back sub-parcels were found in the samples that were collected in runoff paths, and the leaching pattern became traceable with REOs. Moreover, we were able to reconstruct the original surface easily on SEM images. Conclusions Small-scale redistribution and the role of the microtopography of the surface should be considered as an erosional factor in erosion studies in a more detailed way. Behaviour of the REO as a soil sediment tracer has great potential, although questions remain. REO tracing applied with runoff direction modelling and SEM analysis of soil crust samples was suitable to monitor the runoff path, and explain the soil redistribution pattern horizontally and vertically.

Intensive tillage operations, especially moldboard plowing, are widely described as one of the leading causes of soil organic matter (SOM) decrease in cultivated topsoils. Experiments proved that afforestation or even dropped tillage intensity might increase the SOM content of the soil within decades. However, little is known about the forms and sequestration mechanisms of the recently produced organic matter under conservation agriculture practices. Thus, the present study aimed to test the following hypotheses on a Chernozem crop field shifted to conservation tillage: (i) SOM increase appears in the uppermost soil layer without any effect in the subsoil layer; (ii) SOM increase affects each (both labile and stabile) SOM pools of the soil; (iii) the increase modifies the SOM composition of the fractions. The investigations were carried out in a long-term field experiment established in 2002 at Józsefmajor, Hungary. The present study compares the SOM amount and composition of the 0-10 cm and 30-40 cm horizons under plowing, deep cultivation, and no-tillage. Decreasing cultivation intensity resulted in a general soil organic carbon (SOC) concentration increase in both the mineral phase associated OM (stable pool), and the aggregate occluded OM fractions (labile pool). This indicates a relevant saturation deficit in both fractions of the topsoil even though the particulate organic matter fraction did not change. The increase is probably due to the above-ground plant residue input surplus as the SOC content in the 30-40cm layer did not change. The SOM surplus stabilized in the soil did not affect SOM composition differences between depth and fractions resulted in a cultivation-independent chemical SOM composition. The only difference was aromaticity, which showed increasing stratification due to tillage intensity mitigation. These results suggest the highlighted role of dissolved organic matter movement in the profile as the possible driving force of differentiation of aromaticity with depth. The results also underline the role of local circumstances in organic matter composition changes, proving the process's complexity and the difficulties of holistic model construction. The present research was supported by the Hungarian National Research and Innovation Office (NKFIH) K-123953, which is kindly acknowledged.

Stable isotope-based dietary information on the tenth century CE Hungarian population serves as a valuable comparative tool to other dietary stable isotope studies in the region. This study presents a multiproxy approach involving skeletal samples with the least diagenetic alteration and the best-preserved primary signals. Dental and bone samples collected from three cemeteries in northeastern Hungary were investigated using a combination of Fourier-transform infrared spectroscopy (FTIR), stable isotope geochemistry, and strontium isotope analysis. FTIR measurements were used to detect the addition of secondary carbonate to the skeletal apatite carbonate component and to differentiate diagenetically altered samples. Our results suggest that all but the bone apatite carbonate stable isotope values and 87Sr/86Sr ratios are trustworthy and may be used to interpret the diet and migration of the researched individuals. We also determined that the inhabitants of the three tenth century CE Hungarian settlements relied primarily on C3 plants, but that C4 plants, most likely broomcorn millet (P. miliaceum), comprised a moderate portion of their plant-based diet and that animal products were generally consumed in moderate-high amounts. Coupled analyses of carbonate oxygen and strontium isotope compositions revealed that most of the bone apatite carbonate was heavily altered, whereas enamel apatite carbonate samples largely preserved their primary compositions. The bones showing the least amount of diagenetic alteration may partially preserve their primary apatite carbonate compositions, as well as show a combination of primary and secondary signals, which should be taken into consideration when bone apatite carbonate data are interpreted.

The catchment (bedrock and soil) and sediments of lake Bolătău, Romania were studied by high resolution multi-methodological investigations to characterize paleoenvironmental and formation conditions. Particle size analyses, optical and cathodoluminescence microscopy, FTIR-ATR and Raman spectroscopy, X-ray powder diffraction, and XRF were applied for microtextural, chemical, micro-mineralogical and embedded organic material characterization and distribution of the sediments, especially concerning geochemical conditions, like pH and redox potential change. Our results support physical and chemical weathering in the process of soil formation with appearance of the new minerals appear (10Å sized phyllosilicates and clay minerals). Comparison of these studies offer possible differentiation of syn- and diagenetic mineralization, the clarification of debris contribution, microbial mediation and complex mineralization via decomposition of cell and extracellular polymeric substance. Based on the analyses on the abrasives, a suboxic environment prevailed in the depositional area and considerable microbial contribution is proposed via accumulation of lake sediments.

Lake Bolatau-Feredeu is a small (surface: 0.3 ha; catchment area: 31 ha) landslide-dammed lake in Bukovina (Eastern Carpathians, Romania). Elemental concentration, stable isotope composition of carbon and nitrogen, and n-alkane composition of the saturated hydrocarbon fraction of the organic material were analyzed along the sediment profile from Lake Bolatau-Feredeu covering the past ∼700 years. The ranges of δ13C values (−30.5 to −26.6‰) and C/N atomic ratios (10.5 and 15.4) placed the organic material of the recent Bolatau-Feredeu sediment between the C3 Land Plants and the lacustrine algae. The n-alkane proxies provide better distinction between organic matter inputs. Detected major shifts in the n-alkane composition and the C and N concentrations along with the stable isotope compositions pointed towards three distinct stages in the environmental history of the lake-catchment system. The proxy information indicate a substantial landscape change characterized by deforestation and an increase in open pastureland with herbaceous vegetation from ∼1820. The C/N, δ15N, and δ13C values showed the highest variability probably linked to a variable lacustrine environment and decreased productivity in the catchment between ∼1640 and 1760. It can be assumed that the extended periods of lake ice cover during the cold decades experienced at the turn of the 17th-18th centuries resulted in diminished biological productivity both in the lake and its catchment. Finally, afforestation and the decline in lake productivity have been reconstructed for the period of ∼1470–1560.

Fallout isotope (210Pbex,137Cs and 241Am) based dating has been carried out on the near-surface sediment core collected from Lake Bolatau-Feredeu (Bukovina, Romania). The motivation was to improve the chronology of this recent section in connection with significant fluctuations observed in sediment accumulation rates, particle size distribution and primordial radioisotope (i.e. 40K and 232Th) composition. Previously only an extrapolation of a broad-range OxCal age-depth model, which was based on 8 AMS radiocarbon dates from the deeper part of a parallel sediment sequence and tentatively validated for the upper part using the double peaks of the 137Cs activity concentration distribution, was available for the studied section (1-24 cm). Parallel to the previous 137Cs measurement, 210Pb and 226Ra (for a more detailed, 210Pbex-based chronology), 241Am (for an additional time-marker), as well as 40K and 232Th concentrations have also been determined by gamma-spectrometry. In case of the 210Pbex-based chronology, due to a large deviation from a pure exponential distribution, the Constant Flux (CF) model has been used for the calculation of sediment ages and accumulation rates. Although the broad-range OxCal and the CF model were broadly similar down to 22 cm, the 210Pbex-based ages are clearly superior in terms of uncertainty in the uppermost 12 cm, while the broad-range model has smaller uncertainty below 20 cm (>150 years). The CF model gave an average mass accumulation rate of (0.08 ± 0.03) g cm-2 yr-1 for sections 0-11 cm, and (0.03 ± 0.01) g cm-2 yr-1 for sections 12-22 cm, respectively. Significant changes have been observed in the depth distribution of both the particle size distribution and the elemental/isotopic composition of the sediment record, most likely related to the variation observable in the intensity and volume of precipitation in the catchment. The obtained high-resolution records of Lake Bolatau, including multiple radioisotopes, can serve as a regional benchmark for similar studies.