Industrial farming without considering soil biological features could lead to soil degradation. We aimed to evaluate the biochemical properties (BPs) and biological fertility (BF) of different soils under processing tomato cultivation; estimate the BF through the calculation of a simplified BF index (BFIs); determine if the crop was affected by BP and BF. Three farms were individuated in Modena (MO), Ferrara (MEZ) and Ravenna (RA) provinces, Italy. Soil analysis included total and labile organic C, microbial biomass-C (Cmic) and microbial respiration measurements. The metabolic (qCO₂), mineralization (qM) and microbial (qMIC) quotients, and BFIs were calculated. Furthermore, plant nutrient contents were determined. The low Cmic content and qMIC, and high qCO₂ found in MEZ soils indicate the occurrence of stressful conditions. The high qMIC and qM, and the low qCO₂ demonstrated an efficient organic carbon incorporation as Cmic in MO soils. In RA soils, the low total and labile organic C contents limited the Cmic and microbial respiration. Therefore, as confirmed by the BFIs, while MO showed the healthiest soils, RA soils had an inefficient ecophysiological energy state. However, no effects on plant nutrient contents were observed, likely because of masked by fertigation. Finally, BP monitoring is needed in order to avoid soil degradation and, in turn, crop production decline. Full article

Heavy metal contamination was identified in groundwater monitoring wells surrounding a waste deposit facility at the Rönnskär Cu–Pb–Zn smelter in Skellefteå, Northern Sweden, as well as in brackish water and sediments from the nearby harbor. Following an investigative study of the surrounding area, brackish water from the Baltic Sea and sediments from a nearby harbor were also determined to be contaminated. This study investigated the ranges of isotopic compositions of four elements (Cd, Cu, Pb, and Zn) in smelter materials (ores, products, and waste) and polluted groundwater sediments of the affected area. The study’s objective was to evaluate the variability of the polluting source and identify possible isotope fractionation. This study further assesses the viability of using isotopic information to identify the source of the pollutant. These data were used in combination with multi-element screening analysis and multivariate statistical techniques. Expanding the number of elements utilized in isotope tracing empowers our abilities to decipher the source(s) and the extent of environmental exposure from contamination events related to mining and refining operations. Full article

Regular features of ground and surface waters affected by drainage from mine waste include their acidity and elevated concentrations of dissolved metals, with their attendant negative effects on drinking water quality and aquatic life. One parameter that aids in buffering these waters against acidity and sustains aquatic life is dissolved inorganic carbon (DIC). In this study, the chemical and isotopic (δ¹³C) composition of primary calcite and DIC (δ¹³C_DIC) in groundwater and surface waters within and downstream, respectively, of abandoned Cu–W–F skarn tailings at Yxsjöberg, Sweden, were used to trace the biogeochemical processes controlling their respective δ¹³C_DIC signatures. In addition, the δ¹³C signatures of the inorganic (carbonate) fractions of the tailings were used to verify the formation of secondary carbonates within the tailings. Lower average δ¹³C values of the carbonate fractions (δ¹³C_carb = −2.7‰) relative to those of the primary calcite (δ¹³C = +0.1‰) from the orebodies from which the tailings originated pointed to the precipitation of secondary carbonates. These lower δ¹³Ccarb signatures were assumed to represent mixed-source C signals involving isotopically light CO₂ from the atmosphere, the degradation of organic matter in the upper part of the tailings and HCO₃⁻ from calcite dissolution. The groundwater δ¹³C_DIC values (−12.6‰ to −4.4‰) were far lower than the hypothetical range of values (−4.6‰ to +0.7‰) for primary calcite and secondary carbonate dissolution. These signatures were attributed to carbonate (calcite and secondary carbonate) dissolution and the degradation of dissolved organic carbon (DOC) from various organic sources such as peat underneath the tailings and the surrounding forests. Downstream surface water samples collected in May had low δ¹³C_DIC values (−16‰) and high DOC (14 mg C/L) compared to the groundwater samples. These signatures represented the oxidation of the DOC from the wash out of the mires and forests during the snowmelt and spring flood. The DOC and δ¹³C_DIC values of the surface waters from June to September ranged from 6–15 mg·C/L and −25‰ to −8.6‰, respectively. These signatures were interpreted to reflect mixed C sources, including carbonate dehydration by acidity from Fe³⁺ hydrolysis due to the mixing of groundwater with surface waters and the subsequent diffusive loss of CO_{2 (g)}, aquatic photosynthesis, photooxidation, DOC degradation, as well as microbial respiration. Although the ¹³C_DIC signatures of the downstream surface waters seemed to be seasonally controlled and influenced by variable groundwater contributions, the lack of data with respect to DIC concentrations, coupled with multiple potential biogeochemical processes that could influence the DIC pool and ¹³C_DIC values, made it difficult to identify the major regulating process of the ¹³C_DIC signatures. Therefore, other complimentary isotopes and elemental concentrations are recommended in order to decipher the dominant biogeochemical process. Full article

A comprehensive examination of the elemental (including radionuclides and heavy metals), mineral, and grain-size composition of sediments from different areas of the Barents Sea was performed. Sediment cores were sampled in the Central Deep, Cambridge Strait (Franz Josef Land Archipelago), Russkaya Gavan’ Bay (Novaya Zemlya Archipelago), and Bear Island Trough. We aim to evaluate how the modern and more ancient environmental conditions are reflected in the elemental and mineral composition, as well as to test indicative elemental ratios. The applied methods include elemental analysis using gamma-ray spectroscopy, X-ray fluorescence (XRF), Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), and X-Ray Difractometry XRD analysis of minerals. Difference in sedimentation rates, grain-size composition, and sources of material, are reflected in downcore variation of Si/Al, Mn/Fe, P/Al, Ti/K, and quartz-feldspar ratios. At boundary Early Holocene/Late Deglaciation, intensive bottom currents from the West-Southern shelf areas contributed to increase of Si/Al and Zr/Ca ratios. Distinct growth of the Si/Fe ratio within the sediments deposited over Late Pleistocene to Mid Holocene may be caused by increased contents of the coarse sand material, as well as by abundant fluxes of clay-mineral-loaded glacial meltwater during the main deglaciation phase. The Mn/Fe ratio used as redox proxy, displayed peaks at different depths related to oxygen concentration growth in bottom water. Full article

The Zannone Giant Pockmark (ZGP) is a shallow-water (<−150 m) giant depression located on the shelf off Zannone Island (Pontine Archipelago, central Tyrrhenian Sea, Italy), hosting active hydrothermal vents. The ZGP seabed displays different fluid-venting morphologies (pockmarks, lithified pavements, mounds, and cone-shaped structures) and widespread bacterial communities. In this study, we analyzed ROV (Remote Operated Vehicle) images to gain information on seabed geology and the textural, mineralogical, and geochemical composition of authigenic crusts and gravel-sized clasts sampled close to active emissions. ROV images show authigenic dome-shaped crusts composed of native sulfur associated with barite, gypsum, amorphous silica, and secondary hydrothermal minerals (illite–montmorillonite). The gravel-sized clasts are mostly rhyolites strongly affected by hydrothermal alteration (Alteration Index > 88; depletion of some mobile elements and enrichment of some base metals), causing feldspar-destruction, silicification, formation of hydrothermal phyllosilicates, and precipitation of disseminated pyrite. More intense alteration implying the complete obliteration of the primary mineralogy or fabric is represented by quartz-pyrite samples. ZGP seabed morphology and petro-geochemical features of deposits point to the possible occurrence of a sulfide system linked to the degassing of magma similar to that feeding the Pleistocene products of Ponza Island. Full article

Nature is often characterized by systems that are far from thermodynamic equilibrium, and rivers are not an exception for the Earth’s critical zone. When the chemical composition of stream waters is investigated, it emerges that riverine systems behave as complex systems. This means that the compositions have properties that depend on the integrity of the whole (i.e., the composition with all the chemical constituents), properties that arise thanks to the innumerable nonlinear interactions between the elements of the composition. The presence of interconnections indicates that the properties of the whole cannot be fully understood by examining the parts of the system in isolation. In this work, we propose investigating the complexity of riverine chemistry by using the CoDA (Compositional Data Analysis) methodology and the performance of the perturbation operator in the simplex geometry. With riverine bicarbonate considered as a key component of regional and global biogeochemical cycles and Ca²⁺ considered as mostly related to the weathering of carbonatic rocks, perturbations were calculated for subsequent couples of compositions after ranking the data for increasing values of the log-ratio ln(Ca²⁺/HCO₃⁻). Numerical values were analyzed by using robust principal component analysis and non-parametric correlations between compositional parts (heat map) associated with distributional and multifractal methods. The results indicate that HCO₃⁻, Ca²⁺, Mg²⁺ and Sr²⁺ are more resilient, thus contributing to compositional changes for all the values of ln(Ca²⁺/HCO₃⁻) to a lesser degree with respect to the other chemical elements/components. Moreover, the complementary cumulative distribution function of all the sequences tracing the compositional change and the nonlinear relationship between the Q-th moment versus the scaling exponents for each of them indicate the presence of multifractal variability, thus revealing scaling properties of the fluctuations. Full article

The water composition of the river Adige displays a Ca–HCO₃ hydrochemical facies, mainly due to rock weathering. Nitrate is the only component that has increased in relation to growing anthropogenic inputs. The aim of this paper was to identify the origin of the dissolved components in this river and to establish the relationship between these components and critical zone processes within an evolving framework where climatic and human impacts are influencing the riverine system. In particular, emphasis is given to a wide spectrum of isotope data (δ¹⁸O, δ²H, δ¹³C, δ¹⁵N, δ³⁴S, ⁸⁷Sr/⁸⁶Sr, δ¹¹B), which is considered useful for determining water origin as well as natural and anthropogenic impacts on riverine geochemistry. Together with oxygen and hydrogen isotopes, which are strictly related to the climatic conditions (precipitation, temperature, humidity), the carbon, sulphur, strontium and boron signatures can describe the magnitude of rock weathering, which is in turn linked to the climatic parameters. δ¹³C_DIC varies regularly along the riverine profile between −4.5‰ and −9.5‰, and δ³⁴S_SO4 varies regularly between +4.4‰ and +11.4‰. On the other hand, δ¹⁵N_NO3 shows a more scattered distribution between +3.9‰ and +10.5‰, with sharp variations along the riverine profile. ⁸⁷Sr/⁸⁶Sr varies between 0.72797 in the upper part of the catchment and 0.71068 in the lower part. δ¹¹B also shows a rough trend, with values approaching 7.6‰ in the upper part and 8.5‰ in the lower part. In our view, the comparatively low δ³⁴S, δ¹¹B, and high ⁸⁷Sr/⁸⁶Sr values, could be a proxy for increasing silicate weathering, which is a process that is sensitive to increases in temperature. Full article

In the Main Ethiopian Rift (MER) area, rural populations often use water that exceeds the World Health Organization thresholds for fluoride (F^–) and arsenic (As), two elements that are hazardous for human health. In this study, twenty-nine water samples were collected from lakes and hot and cold springs in southern MER to investigate source(s) and health-risk of the F^– and As contamination. According to major ion and trace element analyses, only cold spring water is safe for consumption, whereas hot spring water is the most contaminated. Leaching tests performed with the MER rhyolitic volcanic rocks and their weathered products (fluvio-lacustrine sediments) demonstrate that the main cause of the F^– and As release is geogenic, i.e., not related to anthropogenic activities. The weathering of volcanic glass and minerals (apatites, clays, hydro-oxides) by CO₂-bearing alkaline water induces the mobilisation of F^– and As from solid to liquid phase. This process is particularly fast, when fluvio-lacustrine sediments are involved, and can be further enhanced by hot groundwater leaching. This study, investigating the distribution, sources, and mechanisms of F^– and As release in MER water, could be of interest also for other sectors of the East African Rift and other similar volcano-tectonic settings. Full article

Multi-proxy indices (grainsize distribution, mineralogy, δ¹⁸O, δ¹³C) in sediments from a meander infill in the Middle Loire alluvial plain of central France are used to highlight some aspects of the basin evolution over the period from 0 to 10,000 years BP. During the Late-Glacial and Holocene period, the lacustrine carbonate substratum of the alluvial plain was incised by the Loire River, creating numerous oxbows and channels related to meander migration. The channel fills consist mainly of fine clayey sediments deposited during flooding of the river, with an almost total absence of coarse-clastic and sandy material, except in the basal part. The record of isotope ratio variations together with the distribution of particle sizes allows the evolution of the river dynamics to be constrained. The strong decrease of carbonate δ¹³C in the upper part of the record is ascribed to a progressive closure of the meander and, thus, an increasing control of the C-isotope signature by biological activity in a local environment. Variations in carbonate δ¹⁸O, rather, reflect paleohydrological/paleoclimatic changes at the basin scale. The isotope record of the river dynamics also agrees with the variations in clay mineralogy. Full article

To improve knowledge on salt leaching suitability on different soils, in Arenosols and Cambisols croplands in the coastal area of Ravenna (Italy), soil samples were collected in the non-irrigation winter period and irrigation summer period. Concurrently, waters of the canal network were also investigated. Soil samples were analyzed for pH, carbonate, total organic carbon (TOC), particle size distribution, electrical conductivity (EC), bulk density (BD) and water content at field capacity (FC). Water samples were investigated for pH, EC, biological and chemical oxygen demand, sodium adsorption ratio, phosphorus, nitrogen, sulfates and chlorides. All soils had low TOC concentrations and Arenosols showed the lowest clay content, BD and FC. Soils had similar EC values in winter, but in summer the lowest ones were observed in Arenosols, suggesting that irrigation mitigated salinization in Arenosols, while the high clay content, BD and FC prevented or limited the salt leaching in Cambisols. In summer, the increase of total nitrogen and biological oxygen demand, especially in drainage channels, might suggest the leaching of soluble nutrients and organic matter from soils due to the high irrigation water volumes. Finally, our findings stress the need to consider soil type and properties to contrast soil salinization without negative effects on soil C leaching caused by salt leaching practice. Full article

This work aims to quantify the contribution of agricultural practices to diffuse pollution in cultivated soils. Two samples (the first from the top layer and the second from a depth of about 100 cm) were retrieved from about 1000 soil profiles and analyzed for their potentially toxic elements (PTEs) content (Cd, Cu, Ni, Pb, Zn, Mn). In addition, we collected dedicated soil profiles for three specific types of land use and agronomic practice, namely vine-, cereal- and rice-growing areas. Baseline concentrations and distribution maps were produced. Statistical data treatment, coupled with the results of the dedicated soil profiles, enabled the identification of precise pollution sources and processes. In cultivated soils, PTEs contents prove to be generally well below the Italian regulatory limits, with the exception of Cu in vineyard soils, due to the long-lasting use of Cu-based pesticides. South of Milan and in other urban areas, we attribute the top soil enrichment in Cd, Cu, Pb, and Zn to industrial activities and urban settlement. Ni sporadically exceeds regulatory standards, but its association with Mn and its depth distribution point to a natural origin, mostly due to the occurrence of serpentine. The project demonstrates that although agriculture, especially in the form of vineyards and of intensive cultivation, certainly contributes to pollution, such contribution is exceeded by that deriving from industry and road traffic. Full article