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Global warming is accompanied by increasing water stress across much of our planet. We studied soil biological processes and changes in soil organic carbon (SOC) storage in 30 Hungarian oak forest sites in the Carpathian Basin along a climatic gradient (mean annual temperature (MAT) 9.6–12.1 °C, mean annual precipitation (MAP) 545–725 mm) but on similar gently sloped hillsides where the parent materials are loess and weathered dust inputs dating from the end of the ice age. The purpose of this research was to understand how a drying climate, predicted for this region, might regulate long-term SOC sequestration. To examine the effects of decreasing water availability, we compared soil parameters and processes in three categories of forest that represented the moisture extremes along our gradient and that were defined using a broken-stick regression model. Soil biological activity was significantly lower in the driest (“dry”) forests, which had more than double the SOC concentration in the upper 30 cm layer (3.28 g C/100 g soil ± 0.11 SE) compared to soils of the wettest (“humid”) forests (1.32 g C/100 g soil ± 0.09 SE), despite the fact that annual surface litter production in humid forests was ~ 37% higher than in dry forests. A two-pool SOM model constrained to fit radiocarbon data indicates that turnover times for fast and slow pools are about half as long in the humid soil compared to the dry soil, and humid soils transfer C twice as efficiently from fast to slow pools. Enzyme activity and fungal biomass data also imply shorter turnover times associated with faster degradation processes in the soils of humid forests. Thermogravimetry studies suggest that more chemically recalcitrant compounds are accumulating in the soils of dry forests. Taken together, our results suggest that the predicted climate drying in this region might increase SOC storage in Central European mesic deciduous forests even as litter production decreases.

In agriculture, the use of soil biodegradable mulch films could represent an eco-friendly alternative to conventional plastic films. However, soil biodegradable mulch films incorporated into the soil through tillage, being not only a physical but also a biogeochemical input, is expected to influence the soil quality by affecting its functions. Therefore, the eco-compatibility of these biodegradable plastics needs to be evaluated for their impact on different soil functions. To understand the effect of biodegradable plastics on soil quality (i.e. microbial biomass, nitrogen cycle, and activity of soil enzymes involved in the biochemical processes of carbon and nitrogen), we added increasing quantities of biodegradable plastics in two different soils: a loamy (Cambisol) and sandy (Arenosol) soil. The results highlight that the carbon added through the biodegradable plastics influenced the processes linked to carbon and nitrogen cycles. Significant effects were observed mainly with the highest dose of biodegradable plastics added (1%), resulting in a higher growth of microbial biomass, increased carbon mineralisation, and increased immobilisation of available nitrogen. The results also underline the importance of evaluating the impact of biodegradable plastics in different soils because all the processes considered are also influenced also by soil physicochemical characteristics.

The initial online publication contained a typesetting mistake in the author information. The original article has been corrected.

The occurrence of mineral oil hydrocarbons (MOH) in cellulose-based packaging is mainly due to the offset printing process where MOH are used as a ink pigments' solvent. The MOH migration from paper/paperboard to food is matter of concern for EFSA, members state authorities, consumers, and food industry. In this study, the feasibility to stabilize MOH by adding a sorbent into recycled paper obtained through a common washing process was investigated and the migration to wheat flour/Tenax® assessed. Among several white/pale yellow porous materials, organo-modified powder silica MCM-41-Si(CH3)3 showed the best combination between affinity for MOH (184% dw) and stability to thermal regeneration. A freshly issued newspaper with >3000 mg MOH kg-1 was used to produce recycled paper at a laboratory-scale plant. MCM-41-Si(CH3)3 was added at the pulping step (1% dw) and the sorbent-enriched pulp handled according to a washing paper production process with no effect on the paper optical brightness. The MOH content of the wheat flour in contact with the sorbent-enriched paper under accelerated migration conditions (15 days at 40 °C) resulted 20% of that contacted with control paper (4.3 ± 1.1 and 20.4 ± 5.5 mg kg-1, respectively), despite its contamination was 24% higher than the control. On the contrary, Tenax® contamination resulted 56.0 ± 10.0 and 47 ± 14.0 mg kg-1 when exposed to sorbent-enriched and control paper, respectively.

In this work mild-alkaline semi-solid state pretreatments (NaOH: 2; 4; 6 %, at 25 °C, TS 10 %) were applied to Arundo donax, Sorghum bicolour L. and wheat straw (Triticum aestivum, L.) to test their efficiency on anaerobic biodegradability. The simple sugars (glucose, xylose, arabinose) from structural carbohydrate and the lignin content were analyzed in raw treated samples. Besides to this their structural variation were assessed by means of FT-IR and thermal analysis. The recovery of glucose (1–2 %), xylose (0.4–2.5 %), and arabinose (0.1–8.7 %) in the alkaline eluate showed the treatment produced moderate hydrolysis of the structural components. This was confirmed by the moderate variation of glucose, xylose, arabinose and lignin content determined in the solid residue. On the contrary the FT-IR analysis showed the solid fraction of samples had intense variations in the cellulose and hemicellulose structure (mainly saponification of ester bounds), also confirmed by thermal analysis. The maximum degradation rate (−dx/dtmax; s−1) of cellulose and hemicellulose increased in both Arundo and Sorghum, indicating a structural cleavage. Straw showed moderately increased resilience of hemicellulose by small temperature shifts. A general decrease of the apparent activation energy (E a ) was found in all samples as an indication of decreased structural order favourable to enzymatic hydrolysis and the additional anaerobic biodegradability, as proved by the anaerobic tests in which A. donax showed the highest increase of biodegradability at NaOH 6 % (+30 %) > wheat straw (+22 %) > Sorghum (11 %).

The litter decomposition process depends on the litter chemical composition, especially the ratio between more labile compounds, cellulose, and the recalcitrant lignin and waxes. Their determination is crucial to predict the process, though lignin measurement presents some limitations due to drawbacks of the different methods. Thermal analysis has been successfully applied to several organic materials in order to obtain quali-quantitative information of the chemical structure of the sample. In this work TG-DTA was used in a short-term litter decomposition study of two broadleaf forest stands of contrasting ages, and the results were compared to those obtained with a chemical method (Klason’s method) commonly used to quantify cellulose and lignin. TG-DTA was applied to the litter and to the cell walls (CW) extracted from the litter, whose cellulose and lignin content was determined using the Klason’s method. When applied to litter, thermal analysis showed a weak correlation with the Klason’s method, though it allowed the detection of the dynamics of waxes, that increased during the decomposition and could influence the later stages of the process. Contrastingly, a good correlation between cellulose and lignin determined with the two methods was found when TG-DTA was applied to the CW. In this case TG-DTA, according to NMR data, also highlighted the changes in the CW chemical structure compared with that of the litters, in particular the loss of waxes and the decreased thermostability of aromatic components. Moreover, a new concept of quality of the decomposing litter, based on the balance between the energy stored in the litter and the energy needed to release it obtained by thermal analysis, was recently introduced. Samples of the old forest litter had an initial energetic balance more favorable than those collected in the young stand. At the end of the period, the decrease in litter quality was greater in the young than in the old forest samples, due to the combined effect of the higher degradation of thermolabile substances and the accumulation of more thermostable components. Thermal analysis seems to have a good potential in litter decomposition studies, as it can link structural and energetic changes during the process.

Charcoal is a heterogeneous material exhibiting a diverse range of properties. This variability represents a serious challenge in studies that use the properties of natural charcoal for reconstructing wildfires history in terrestrial ecosystems. In this study, we tested the hypothesis that particle size is a sufficiently robust indicator for separating forest wildfire combustion products into fractions with distinct properties. For this purpose, we examined two different forest environments affected by contrasting wildfires in terms of severity: an eucalypt forest in Australia, which experienced an extremely severe wildfire, and a Mediterranean pine forest in Italy, which burned to moderate severity. We fractionated the ash/charcoal layers collected on the ground into four size fractions (> 2, 2-1, 1-0.5, < 0.5 mm) and analysed them for mineral ash content, elemental composition, chemical structure (by IR spectroscopy), fuel source and charcoal reflectance (by reflected-light microscopy), and chemical/thermal recalcitrance (by chemical and thermal oxidation). At both sites, the finest fraction (< 0.5 mm) had, by far, the greatest mass. The C concentration and C/N ratio decreased with decreasing size fraction, while pH and the mineral ash content followed the opposite trend. The coarser fractions showed higher contribution of amorphous carbon and stronger recalcitrance. We also observed that certain fuel types were preferentially represented by particular size fractions. We conclude that the differences between ash/charcoal size fractions were most likely primarily imposed by fuel source and secondarily by burning conditions. Size fractionation can therefore serve as a valuable tool to characterise the forest wildfire combustion products, as each fraction displays a narrower range of properties than the whole sample. We propose the mineral ash content of the fractions as criterion for selecting the appropriate number of fractions to analyse.

High silica zeolite Y has been positively evaluated to clean-up water polluted with sulfonamides, an antibiotic family which is known to be involved in the antibiotic resistance evolution. To define possible strategies for the exhausted zeolite regeneration, the efficacy of some chemico-physical treatments on the zeolite loaded with four different sulfonamides was evaluated. The evolution of photolysis, Fenton-like reaction, thermal treatments, and solvent extractions and the occurrence in the zeolite pores of organic residues eventually entrapped was elucidated by a combined thermogravimetric (TGA-DTA), diffractometric (XRPD), and spectroscopic (FT-IR) approach. The chemical processes were not able to remove the organic guest from zeolite pores and a limited transformation on embedded molecules was observed. On the contrary, both thermal treatment and solvent extraction succeeded in the regeneration of the zeolite loaded from deionized and natural fresh water. The recyclability of regenerated zeolite was evaluated over several adsorption/regeneration cycles, due to the treatment efficacy and its stability as well as the ability to regain the structural features of the unloaded material.

none 6 no In this study, we assessed the carbon (C) distribution within soil aggregates, macroaggregates (Macro), microaggregates (micro), and silt and clay (s + c) through three soil depths (0– 0.15, 0.15–0.30, and 0.30– 0.60 m) and af ter 9 years of land conversion from two annual crops continuous wheat and maize/wheat rotation to Miscanthus and giant reed, respectively. The 13 C natural abundance analysis wa s combined with physical fractionation to trace the fate of the new C that wa s derived from Miscanthus and giant reed in aggregate fractions. Macro always represented the highest proportion of the soil and the highest amount of C. In Miscanthus, the amount of C decreased from the 0–0.15 to the 0.30–0.60 m soil layer, whereas the C storage capacity of micro and s + c increased with depth. In giant reed, the distribution of the soil fractions and the associated C were more uniform in all of the layers. The new C derived from the perennial species wa s mainly concentrated in the upper layer in the Macro under Miscanthus , whereas it wa s more evenly distributed in the three layers and the fractions under giant reed. Irrespective of the fractions, in the Miscanthus plantation, the great C accumulation wa s derived from both the new C directly entering the soil and the old C that wa s preserved from mineralization. Conversely, in the giant reed plantation, C accumulation wa s only derived from the new C component. These patterns reflect the different structure of the root apparatus of the two perennial species, which were mainly concentrated in the upper layer of Miscanthus and were more evenly distributed in soil profile of the giant reed. It is likely that this is responsible for the different mechanisms of C storage and turnover. mixed Gioacchini, Paola; Cattaneo, Francesca; Barbanti, Lorenzo; Montecchio, Daniela; Ciavatta, Claudio; Marzadori, Claudio Gioacchini, Paola; Cattaneo, Francesca; Barbanti, Lorenzo; Montecchio, Daniela; Ciavatta, Claudio; Marzadori, Claudio

In the present study, the chemical features of municipal wastewater sludges treated in two-phase separate digesters (one for acetogenesis and the other one for methanogenesis), were characterized by using chemical analysis, stable carbon isotope ratios (delta(13)C), HS-SPME-GC-MS, TG-DTA analysis and DRIFT spectroscopy. The results obtained showed that sludges from acetogenesis and methanogenesis differed from each other, as well as from influent raw sludges. Both processes exhibited a diverse chemical pattern in term of VFA and VOC. Additional variations were observed for delta(13)C values that changed from acetogenesis to methanogenesis, as a consequence of fermentation processes that led to a greater fractionation of (12)C with respect to the (13)C isotope. Similarly, the thermal profiles of acetogenesis and methanogenesis sludges greatly differed in terms of heat combustion produced. These changes were also supported by higher lipid content (probably fatty acids) in acetogenesis than in methanogenesis, as also shown by DRIFT spectroscopy.

Thermal analyses (TG-DTA), elemental composition and isotope analyses (13C and 15N) were performed on humic acids (HA) from peats, leonardites and lignites, in order to investigate their structure and the changes taking place during the humification process. Thermal analyses showed structural differences between HA samples in relation to their coalification rank. In particular the lignite HA were characterized by a more stable chemical composition at high temperatures. The δ13C and δ15N values can provide information on the biogeochemical processes involved in HA formation. In particular, peat HA were linked to anoxic environments that enable plant residues to persist in their structure. In contrast, leonardite and lignite HA formation seems to be governed by different biogeochemical processes from those responsible for peat diagenesis. However, the isotopic analyses did not provide any distinction between leonardite and lignite HA. On the basis of the data presented in this study, it may be concluded that TG-DTA and isotope ratio measurements are powerful tools for investigating the formation pathway of humic substances from coals. © 2004 Elsevier Ltd. All rights reserved.

We studied the effects of Pb pollution on soil dehydrogenase and phosphatase activity. Samples of four soils (Saxe, Podesta, Porto Teulada, and Sa Xia Manna) were collected from various locations in southwestern Sardinia, Italy. The soils, which differ mainly in heavy metal contents of pedologic origin (Cu, Zn, Cd, and Pb), were treated with Pb (0, 100, 500, 1000, and 5000 μg Pb g-1 soil) and incubated in the laboratory. Samples of the incubated soils were collected periodically (0, 1, 2, 4, 8, and 16 weeks) and the enzymes were measured. Soil dehydrogenase activity was influenced by both the Pb additions and variations in soil moisture content. Only the addition of 5000 μg Pb g-1 soil led to a significant decrease in dehydrogenase activity compared to the controls, while the other doses of Pb did not always result in a clear reduction in enzyme activity. Drying the soil led to a considerable reduction in dehydrogenase activity, sometimes so far as to render the differences found between the various treatments not statistically significant. Soil phosphate activity was also influenced by the Pb additions, but the effect of the variation in soil moisture content was less than that found for the dehydrogenase. After the 2nd week of incubation, the phosphate activity in the Podesta and Saxe soils had decreased proportionally to the increase in Pb content. At the end of the incubation period, in the Porto Teulada and Sa Xia Manna soils, a net reduction in phosphatase activity versus controls was found only at the highest Pb concentration. Although both enzyme activities were influenced by the Pb additions, the phosphate activity was less sensitive to variations in the soil moisture content and may thus be a more suitable indicator for soil pollution by Pb.

In organic farming winter cereals, as cover crops, provide nutrients, when they return to soil as crop residues. The fate of N deriving from two decomposing 15N-labelled winter cereals, with or without the supply of an organic N fertiliser, was studied in a field experiment. The stabilisation of residues N in soil aggregates and the portion lost from the system were also evaluated. Barley or triticale residues were incubated alone or with hydrolysed leather (L) in mesocosms over one year. The residues derived N was measured in soil and in soil aggregate size fractions >250 μm (macroaggregates, macro); 53–250 μm (microaggregates, micro)

Although acid soils are common in forest ecosystems, and there is documented evidence of pH influencing transformations of organic matter in soil, there are surprisingly few studies on the influence of soil pH on the chemical structure of physically fractionated soil organic matter (SOM). The aim of this study was to characterize the influence of pH on the chemical and physical processes involved in SOM stabilization. Forest soils of different pH (4.4 and 7.8) sampled from two long-term experiments at Rothamsted Research (UK) were physically fractionated. The free light fraction (FLF), the intra-aggregate light fraction and the fine silt and clay (S + C

Humic acid extracted from the A horizon of a Chernozem soil and their different molecular size (MS) fractions obtained by SEC–PAGE were investigated using thermal (TG–DTA), spectroscopic (DRIFT) and isotopic (δ13C) analyses. Moreover, the molecular structure of the high temperature stable fraction (residues above 400 °C) was studied by DRIFT spectroscopy. The lowest MS fraction (C + D) was characterized by the highest content of aromatic compounds and by the lowest content of aliphatic and carboxyl groups, carbohydrates and amino acids with respect to the other fractions. Nevertheless, the aromatic structure of A and B fractions seems to be more complex. The δ13C values which indicated the presence of urea traces in the lowest MS fractions (B and C + D) may be due to the purification process.

The purpose of the present study is to investigate, by means of thermogravimetric analysis (TG) and differential thermal analysis (DTA), diffuse reflectance infrared Fourier transform (DRIFT) and 2D nuclear magnetic resonance (NMR) spectroscopies, the structural features of the humic-like fraction (HLF) from olive pulp (OP), its effluents originated from the fermentation processes for hydrogen (EH2) and methane production (ECH4) and humic acid (HA) from soil amended with each of these materials. A considerable structural modification emerged between the HLF, in particular from the ECH4 effluent, which was characterised by a high content of polyphenolic and polypeptidic substances. The short-term amendment trial with OP and EH2 indicated that no chemical or structural changes in soil HA appeared. In contrast, the amendment with ECH4 substantially influenced the chemical and structural composition of soil HA. The structural interpretation performed by 2D NMR indicated the presence of aliphatic and aromatic protons while the sugar-like content and O-CH3 groups decreased with respect to the soil control HA. It emerges from this study that olive wastes contain stabilised humic-like material that may be recycled as an amendment in areas where olive trees are cultivated.

In this study, five different slow-release fertilizers were incubated in two soils and their N dynamics was followed for four months. Four of the fertilizers used were organic: two were hydrolyzed fur, one was made by hydrolyzed fur, farmyard manure, horn and hoofs (Endurance), and one contained synthetic organic N (isobutylidendiurea, IBDU). The fifth, on the contrary, was a mineral fertilizer (Entec 26) containing both NO3- and NH4+ and a nitrification inhibitor (3,4 DMPP). The two soils used were a sandy loam (SL) and a clay loam (CL). The fertilizer-N release was conditioned by both the fertilizers and the soil characteristics. The highest accumulation of mineral N as NO3- was observed in the SL soil for all the treatments. The lowest net N release was observed in both soils with End. which was found to be the most resistant to microbial attack and degradation. The two fur-based fertilizers released similar amount of N which was higher in the SL soil than in the CL soil. The highest accumulation of fertilizer-derived N in the CL soil resulted from IBDU, however, the net accumulation of N in the SL soil with this fertilizer, was even higher than the amount of N initially added. This fact was attributed to an increase in mineralization of the soil’s native organic N. A real positive "priming effect" was also observed in the SL soil with E26. On the contrary, E26 caused a low level of N accumulation in the CL soil.

Humic acids (HAs) extracted from soils developed under two Norwegian spruce (Picea abies, (L.) Karst) subalpine forests of northern Italy were characterized using chemical, thermal (TG-DTA) and spectroscopic (DRIFT) analyses. The samples were taken from five sites which differed in orientation (northern and southern exposure) and vegetal cover at different old age: grassland, regeneration, immature and mature stands. In general, the thermal patterns of HAs were similar (three exothermic reactions appeared around at 300, 400 and 500 degrees C) in both sites in grasslands and regeneration while a considerable modification appeared in HA from stands of different age at northern and southern exposure site. DRIFT spectroscopy confirmed the differences observed through TG-DTA analysis. In particular the main structural changes were ascribed to modification of carbonyl group and of CH stretching in aliphatic components in each HAs from different sites.

Thermal analysis (TG-DTA) and FT-IR spectroscopy have been performed on calcium-pectate membranes to investigate their structure and the consequent variation caused by aluminium sorption. Calcium-polygalacturonate (Ca-PG) membranes, system models of the soil-root interface, were exposed to aluminium solutions at different concentrations (25-800 mM). Three different pHs (3.50, 4.00 and 4.50) were chosen to study also the influence of different aluminium species such as Al3+, Al(OH)2+ and Al(OH)2+ on the structure of the Ca-PG membrane. The DTA profiles and the FT-IR spectra showed how the aluminium sorption induces structural modifications leading to a reorganisation of the chain aggregates and a weakening of the structure. Higher pHs, i.e. 4.00 and 4.50, and thus the presence hydrolytic aluminium species and the related higher calcium content would maintain a more regular structure than at pH 3.50. At pH 3.50, both the effect of Al3+ and a major calcium release induces a greater weakening of the structure causing an earlier collapse of the membrane. This suggests that Al3+ could be more toxic to plants than the hydroxyl-Al species.

Humic acids extracted from peats (P), brown coals (BC) and lignites (L), were characterized using different (chemical, 1H-nuclear magnetic resonance spectroscopy and differential thermal analysis) techniques. Fourteen variables were obtained from these analyses and only five were selected because uncorrelated in multiple partial correlation. The chosen variables were C concentration, aliphatic and aromatic components and the heat of reaction of the second exothermic peak. The multivariate discriminant analysis was performed on these variables and a discriminant function was obtained which was able to efficiently separate the P, BC and L. This function enables simple predictions on samples of unknown origin. The straightforward method proposed and the results obtained are discussed. © 2003 Elsevier Science Ltd. All rights reserved.

The stabilization level of the organic matter of compost from MSW has been monitored using the degree of humification (DH), the isoelectric focusing (IEF) and a Bimodal Gaussian Distribution (BGD) of pK of –COOH and phenolic –OH groups of HA. The results obtained show that these methods are able to monitor the processes.

The or ganic matter of Irish peat of Sphagnum was extracted with 0.1 M NaOH and separated into humic (HA) and fulvic (FA) acids. Afterwards, HA and FA fractions were obtained at different nominal molecular weight using a tangential ultr a- filtration system. The behaviour of such fractions has been studied both in acid and alkaline solutions. Solutions at dif ferent ionic strength ha ve been titrated under different conditions and the resulting cur ves have been elaborated through a computer program based on a bimodal Gaussian distribution. The typical parameters (pKA mean value and dispersion degree) of the two main groups of HA and FA acidic functionalities have been determined.

Energy crops are designed for biomass production to generate bioenergy. Their recent introduction in the Po Valley (North Italy) is connected to the mitigation of environmental effects of the intensive management. Intensive management has a dramatic impact on the soil ecosystem of the area, reducing soil organic matter, degrading soil structure and altering nutrient cycles by reducing microbial biomass, and thus compromising soil productivity. Soil organic carbon (SOC) content in the Emilia-Romagna region is the lowest in the Po Valley (