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In the Mediterranean basin, the treatment and disposal of olive mill pomace (OMP) remain a salient environmental issue for the olive oil- producing industry. This study assesses the effects of olive-processing technology (three- phase and two-phase systems) on the potential use of OMP as a soil amendment. Samples from 12 Croatian olive mills were analysed for their total phenolic content (TPC), residual oil fraction, and elemental concentration. The samples were profiled using FT-IR spectroscopy and structurally characterised using SEM-EDS. Compared to three- phase samples, two-phase OMP was more acidic (pH 4.5 vs pH 5.0), with a higher TPC (3835 vs 1576 mg/kg f.w.), oil content (11.7 vs 7.5 % d.w.), EC (5.1 vs 3.0 mS/cm), and levels of Ca (1.34 vs 1.20 g/kg d.w.) and Cu (10.4 vs 7.0 mg/kg d.w.). Similar values of C/N (61 vs 72), N (10 vs 8.1 g/kg d.w.), P (1040 vs 691 mg/kg d.w.), and K (13.7 vs 8.1 g/kg d.w.) were observed. The amounts of Cr, Cu, Ni, and Zn were below EC limits in both cases. The EDS mapping revealed that Ca was concentrated at sharp-edged OMP particles while K was evenly distributed, suggesting that pelletized OMP compost is preferable for amending soil to obtain a homogeneous distribution of nutrients. It was also possible to distinguish between OMPs based on oil and lignin absorption bands in their FT-IR spectra. According to the obtained results, composting is recommended for both types of OMP to produce a safe product for amendment purposes.

The addition of compost or biochar to soils is a viable strategy to increase soil organic matter (SOM), especially if the amendments are produced from biomass wastes. The need for sustainable land management without sacrificing agricultural production is critical to alleviate negative impacts on soil quality, including loss of SOM and nutrients. Turning sewage sludge (SS) into compost or biochar can help in lowering its potential negative effects on soil and providing a viable strategy for SS management through its recycling in agriculture. The aim of this study was to evaluate the short-term impact of SS in its composted or biochar form on the fungal and bacterial communities of the Terra Rossa soil by high-throughput sequencing. A greenhouse pot trial was conducted using a 2-factor experiment consisting of amendment type (compost, biochar) and sampling time (Day 0, 30, and 60) as the main factors. The results showed no effect of SS addition on fungal and bacterial species richness, as well as a shift in relative abundance of the fungal phylum Zygomycota and bacterial phylum Firmicutes and Thermomicrobia. Both bacterial and fungal community analyses showed changes when composted sewage sludge was applied. However, only the fungal community differed from the control soil by the end of the 60-day vegetation period of Chinese cabbage.

Predictions of radionuclide dose rates to freshwater organisms can be used to evaluate the radiological environmental impacts of releases from uranium mining and milling projects. These predictions help inform decisions on the implementation of mitigation measures. The objective of this study was to identify how dose rate modelling could be improved to reduce uncertainty in predictions to non-human biota. For this purpose, we modelled the activity concentrations of 210Pb, 210Po, 226Ra, 230Th, and 238U downstream of uranium mines and mills in northern Saskatchewan, Canada, together with associated weighted absorbed dose rates for a freshwater food chain using measured activity concentrations in water and sediments. Differences in predictions of radionuclide activity concentrations occurred mainly from the different default partition coefficient and concentration ratio values from one model to another and including all or only some 238U decay daughters in the dose rate assessments. Consequently, we recommend a standardized best-practice approach to calculate weighted absorbed dose rates to freshwater biota whether a facility is at the planning, operating or decommissioned stage. At the initial planning stage, the best-practice approach recommend using conservative site-specific baseline activity concentrations in water, sediments and organisms and predict conservative incremental activity concentrations in these media by selecting concentration ratios based on species similarity and similar water quality conditions to reduce the uncertainty in dose rate calculations. At the operating and decommissioned stages, the best-practice approach recommends relying on measured activity concentrations in water, sediment, fish tissue and whole-body of small organisms to further reduce uncertainty in dose rate estimates. This approach would allow for more realistic but still conservative dose assessments when evaluating impacts from uranium mining projects and making decision on adequate controls of releases.

In recent years, the production and application of biochar as a soil amendment produced from pruning residues has gained attention worldwide. Since the effect of grapevine rootstock type on grapevine-pruning residues used as feedstock for biochar production had not yet been researched, the present research was performed. Two grapevine rootstocks, different in vigor, were selected, with the hypothesis that they would affect their chemical composition and, consequently, the composition of the produced biochar. In this work, grapevine-pruning residues of the indigenous variety “Istrian Malvasia” (Vitis vinifera L.) grafted on 420A and SO4 rootstocks were analyzed and used for biochar production under three peak temperature programs (400 °C, 500 °C, and 600 °C). Higher pyrolysis temperature decreased yield but increased EC, ash, and TC content, as well as the content of most of the studied elements. On the other hand, grapevine rootstock type affected biochar EC, ash content, and specific surface area. Results showed that a more vigorous rootstock affects the produced biochar qualities by enhancing the above-mentioned properties. The present research showed that biochar produced from grapevine-pruning residues, especially at 500 °C or 600 °C, could be a valuable tool for the valorization of this biomass as a soil amendment.

Composted sewage sludge (CSS) gained attention as a potential fertilizer in agriculture. Application of CSS increases soil microbial activity and microbial biomass, however, it can also lead to increased chemical and microbiological risks. In this study, we performed microcosm experiments to assess how CSS reshapes the microbial community of diluvial sand (DS) soil. Further, we assessed the potential of CSS to increase the persistence of human pathogens in DS soil and the colonization of Chinese cabbage (Brassica rapa L. subsp. pekinensis (Lour.) Hanelt). The results revealed that CSS substantially altered the prokaryotic community composition. Moreover, addition of CSS increased the persistence of Salmonella enterica serovar Typhimurium strain 14028s and S. enterica serovar Senftenberg in DS soil. However, the enhanced persistence in soil had no impact on the colonization rate of B. rapa grown on soil inoculated with Salmonella. We detected Salmonella in leaves of 1.9% to 3.6% of plants. Addition of CSS had no impact on the plant colonization rate. The use of sewage sludge composts is an interesting option. However, safety measures should be applied in order to avoid contamination of crop plants by human pathogens.

This study set out to evaluate the effect of using sewage sludge-derived compost (SSC) or biochar (SSB) as a soil amendment on the phytoaccumulation of potentially toxic elements, PTE (Cd, Cr, Cu, Ni, Pb, Zn) and natural radionuclides (U-238 and Th-232) by Chinese cabbage (Brassica rapa L. subsp. pekinensis (Lour.) Hanelt) in terra rossa and rendzina soils, which are the two common soil types in Croatia. The experiment consisted of a greenhouse pot trial using a three-factor design where soil type, sludge post-stabilisation procedure and amendment rate (12 and 120 mgP/L) were the main factors. At harvest, the concentrations of analytes in the substrate, leaves and roots were measured, from which the edible tissue uptake (ETU) and concentration ratios (CR) were determined. Also, the average daily dose (ADD) and hazard quotient (HQ) were determined to assess the health risk, as well as soil contamination factor (CF). The results showed that neither adding SSC nor SSB affected the soil loading at the rates applied, suggesting a low risk of soil contamination (CF ≤1). The ETU of Cd, Cu, and Zn were 0.0061, 1.23, and 0.91 mg/plant from compost-amended soil and 0.0046, 0.78 and 0.65 mg/plant for biochar-amended soil, respectively. This difference suggests that their ETU was higher in compost-amended soils than in soils treated with biochar. The CR data indicate that the bioavailability of Cu (CR of 5.30) is highest at an amendment rate of 12 mgP/L, while for Zn (CR of 0.69), the highest bioaccumulation was observed with an amendment rate of 120 mgP/L. Translocation of Cr, Ni, Pb and 238U to the leaves was limited. Overall, the HQ (

This study assesses the potential use of different types of stabilized sewage sludge as a soil amendment by considering their physicochemical characteristics, nutritional status, and their trace metal and radionuclide content. The concentrations of trace metals and radionuclides were determined using ICP-OES and gamma-ray spectrometry, respectively. For determining nutritional status and chemical characterization, this study followed standard ISO-recommended procedures. Data analysis revealed that anaerobic sludge contains higher concentrations of Cr, Hg, and Ni compared to aerobic and non-biologically stabilized sludge. A similar observation was observed in the case of 226Ra, 210Pb, 228Ra, and 228Th. Furthermore, the high levels of P and N in aerobic sludge suggest that biologically stabilized sludge has the potential to be a good fertilizer. In addition, the study finds strong evidence that nutrients are involved in the adsorption of metals and radionuclides onto sludge biomass. Overall, eight of the nine studied sludge samples are safe for agricultural use since the concentrations of trace metals fall well below the limits set by Croatian legislation (NN 38/08). In addition, the levels of radionuclides do not pose a radiological risk. This means that soil conditioning with sewage sludge remains a viable strategy for nutrient recovery from municipal waste, although long-term impact assessments of repeated applications are necessary.

Organic amendments are often reported to improve soil properties, promote plant growth, and improve crop yield. This study aimed to investigate the effects of the biochar and compost produced from sewage sludge and olive pomace on soil hydraulic properties, water flow, and P transport (i.e., sorption) using numerical modeling (HYDRUS-1D) applied to two soil types (Terra Rosa and Rendzina). Evaporation and leaching experiments on soil cores and repacked soil columns were performed to determine the soil water retention, hydraulic conductivity, P leaching potential, and P sorption capacity of these mixtures. In the majority of treatments, the soil water retention showed a small increase compared to the control soil. A reliable fit with the modified van Genuchten model was found, which was also confirmed by water flow modeling of leaching experiments (R2 0.99). The results showed a high P sorption in all the treatments (Kd 21.24 to 53.68 cm3 g&ndash, 1), and a high model reliability when the inverse modeling procedure was used (R2 0.93 - 0.99). Overall, adding sewage sludge or olive pomace as compost or biochar improved the Terra Rosa and Rendzina water retention and did not increase the P mobility in these soils, proving to be a sustainable source of carbon and P-rich materials.

Environmental concern due to plant accumulation of natural radionuclides is a major concern in uranium mining areas. To evaluate the risk associated with the transfer of radionuclides to edible plants, the uptake of 238U, 226Ra, and 210Pb by Chinese cabbage (Brassica rapa L. subsp. pekinensis (Lour.) Hanelt) grown in soils contaminated with uranium-mill tailings (UMT) was investigated. Test plants were grown under controlled conditions in substrate composed of soil and UMT in different ratios. Activity concentrations of 238U, 226Ra, and 210Pb in substrate, leaves, and roots were measured and the concentration ratios determined. Soil characteristics were determined, since they directly affect bioavailability of radionuclides. Concentration ratios of 238U, 226Ra, and 210Pb in leaves varied from 0.001 to 0.006, 0.024 to 0.172, and 0.004 to 0.011, respectively, and in roots from 0.020 to 0.126, 0.015 to 0.241, and 0.033 to 1.460, respectively. Concentrations of 238U, 226Ra, and 210Pb in leaves and roots were found to correlate with the amount of 238U, 226Ra, and 210Pb in the substrate. A higher amount of 226Ra accumulated in aboveground parts (57–877 Bq kg−1 d. m. for leaves) compared to 238U (0.6–4.7 Bq kg−1 d. m. for leaves) and 210Pb (8–53 Bq kg−1 d. m. for leaves), which were mainly stored in the roots. The relationships between the amount of radionuclides in plants and soil characteristics and their role in radionuclide uptake are discussed and critically evaluated.

The transfer of 238U and 226Ra to Chinese cabbage (Brassica rapa L. subsp. pekinensis (Lour.) Hanelt) was investigated from soils contaminated with uranium-mill tailings (UMT) by means of a pot experiment in laboratory-based conditions applying different levels of soil contamination under various growing conditions. Activity concentrations for 226Ra in Chinese cabbage varied from 56–276, 156–502 and 277–877 Bq kg-1 dry mass for 20, 40 and 60 % of UMT content in the soil, respectively, and for 238U from 1.0–2.3 and 2.3–4.7 Bq kg-1 dry mass for 40 and 60 % of UMT content in the soil, respectively. The results showed increased accumulation of 226Ra and low accumulation of 238U in cabbage leaves in more contaminated soil.

Summary Different radiometric techniques for the determination of 238U, 226Ra and 210Pb are presented and compared in terms of detection limits with mass spectrometric techniques. It can be concluded that when samples with low activity concentrations have to be measured, the method of choice in the case of 238U should be either RNAA/INAA or alpha particle spectrometry. In the case of 226Ra and 210Pb the best performance can be expected by the alpha spectrometry, whereas drawback of waiting for establishing secular radioactive equilibrium of 210Pb with 210Po makes techniques like beta counting and LSC more attractive for the determination of 210Pb. In addition, a case study on monitoring the former uranium mine Žirovski vrh is presented along with the used methodology and the summarised measurement results.

Uranium mining and milling activities are one of the major causes of radioactive contamination of the environment. Radionuclides, especially uranium decay-chain products, are released from plant wastes into the soil and water and consequently into vegetation where they may accumulate. Transfer of radionuclides thus represents a radiological risk to humans and non-human organisms due to accumulation of radionuclides in target tissues and the consequent ionising radiation. The uranium mine at Žirovski vrh in Slovenia, which operated from 1985 to 1990, processed about 600,000 t of U-ore. Operational wastes were deposited at the Borst and Jazbec sites. According to several studies, an environmental radiological risk to biota could be observed at sites exposed to radioactive contamination. A modelling approach can be used to estimate the risk in such areas. The ERICA tool is one of the more widely used models, developed to assess the environmental risk from ionising radiation to wildlife. In the present study, the ERICA Tool was applied for the assessment of the radiation impact on wildlife in the Žirovski vrh influential area. ERICA reference organisms, native plants and aquatic organisms were included in the assessment to screen the risk to different organisms. Total dose rate to organisms were up to 3.49, 33.0 and 2.58 μGy h −1 for Juncus effusus , lichens and Austropotamobius torrentium , respectively. Dose rates to other organisms are also presented and discussed.

The impact of a U-mill tailing on radionuclide accumulation by plants was assayed. In particular, a preliminary screening of 226Ra, 238U and 230Th in Marsh marigold (Caltha palustris L.), soft rush (Juncus effusus L.) and Tall Moor grass (Molinia arundinacea (L.) Moench) grown in a marsh habitat is presented. Activity concentrations for the studied radionuclides and their transfer factors for the particular plants are shown and discussed.

The uranium mine and mill at Žirovski vrh, Slovenia, operated from 1982 to 1990. After processing, the uranium mill tailings were deposited onto the Boršt waste pile lying close to the mine. Radioecological studies focused on assessing the mobility and bioavailability of deposited radionuclides were initiated some five years ago. The mobility of U-238, U-234, Th-230 and Ra-226 in soil was studied by applying sequential extraction protocols. The highest activity concentrations were found at the bottom of the waste pile. Uranium isotopes were the most mobile, followed by Ra-226 whose mobility appeared to be suppressed by high sulphate concentrations and Th-230. The wetland plants grown in soils contaminated with seepage waters from the tailings contained higher levels of U-238, Ra-226 and Th-230 compared to plants from a control site. The activity concentration of Ra-226 was the highest in all studied plant species. The radiological risk to wildlife around the mine area as assessed by the ERICA Tool was negligible. Activity concentrations in bovine milk from the area of Žirovski vrh were comparable to the reference location, except for uranium where the content was higher. The combined annual effective dose for adults consuming milk from the Žirovski vrh area is 13.0 ± 1.7 μSv a-1.

Although the influential area of the former uranium mine at Zirovski vrh, Slovenia has been under continuous radiological monitoring, more detailed radioecology studies, focused on assessing mobility and bioavailability of deposited radionuclides, were initiated about five years ago. The mobility of 238U, 234U, 230Th and 226Ra was studied applying two sequential extraction protocols. The results revealed that both sequential extraction protocols are not comparable as the data obtained are protocol- and radionuclide-dependent. It was found that the most mobile ones were uranium isotopes, followed by 226Ra and 230Th. In addition, uptake of particular radionuclides by the wetland plants (Molinia arundinacea, Juncus effusus and Caltha palustris) grown in soils contaminated with seepage waters from the tailings was studied. The plants contained higher levels of 238U, 226Ra and 230Th compared to the plants from the control site. Activity concentration of 226Ra was the highest for all three plant species. Activity concentration of natural radionuclides in milk collected from the area of Zirovski vrh was comparable to the reference location, except for uranium where the content was higher. The combined annual effective dose for adults consuming milk from the Zirovski vrh area is 13 ± 2 μSv yr−1.