Wood ashes can be used, e.g., as soil fertilizer or in construction materials; however, it is important to ensure that such use will not cause spreading of heavy metals and subsequent harm to the ...environment. Wood fly ashes (WFAs) generally have higher concentrations of heavy metals than wood bottom ashes. This paper focuses on the leaching of heavy metals from WFA, specifically identifying WFA characteristics that influence the leaching and changes in leaching caused by hydration and carbonation in ambient air. Chemometric modeling based on characteristics for eight different WFAs suggested that the leaching of Cr and Zn was associated with the concentration of K and the leaching of SO
, indicating a connection to the soluble K
(SO
) commonly found in WFAs. During the aging, both pH and conductivity of the WFAs decreased showing the formation of new phases. The leaching of Cd, Cu, Ni, and Pb was low initially and decreased to non-measurable after the aging. So did the leaching of Zn except from one of the WFAs. Thus, the part of the heavy metals, which were leaching originally, was built into the newly formed phases. The Cr leaching also showed a general decrease during the aging, however, not to similarly low levels. This means that the leaching Cr fraction was either not influenced by the aging processes or the formed phases contained water-soluble Cr. The continued leaching of Cr needs more attention as it may be the toxic and carcinogenic Cr(IV). As the chemistry and mineralogy of WFAs, inclusive of the mobility of the heavy metals, are subject to changes, increased knowledge on the chemistry determining these changes is needed to choose environmentally sound recycling options.
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•Validation and demonstration of a new system to analyze soluble salts simultaneously.•The simultaneous analysis guarantees the representativeness of the real situation.•A simple ...modular system-based ion chromatography and titrimetry is proposed.•The need of include more ions in the norms as bicarbonate or cations is demonstrated.•A more specific legislation and the establishment of limits of the ions is required.
A soluble salt analysis is crucial in the evaluation of the conservation state of the built heritage. In this sense, there are European norms that indicate the way to measure them and the levels that are hazardous. However, in those norms, only a few anions are included, the cations are undervalued, and the required analysis is not simultaneous. All of these could lead to incorrect conclusions because of the lack of representativeness of the real situation. Moreover, there are incongruences observed in the norms, because although the levels of some anions are established the quantitative analysis is only recommended. In this work it is demonstrated how the quantitative analysis of anions and cations is crucial for the correct understanding of the conservation state of a historical building under conservation works. For that, a specific ionic chromatographic system has been designed that provides the analysis of anions, cations and carbonate/bicarbonate in a simultaneous way and it was applied in brick and mortar samples for the study of Punta Begoña Galleries. In this way, it was possible to identify the affection depending on the studied materials, being the atmospheric acid gases the main problems to the mortar and the rainwater and marine aerosol for bricks. Moreover, the damage level of the analysed areas was quantified and the most critical points to be restored were identified. This work demonstrates the need of a change of mind in the soluble salt analysis regarding the ions included in the norms and the way to measure them.
•Technique for simultaneous desalination and consolidation.•Technique based on ionic mobilization by electric field.•This technique reduces the salt content to 100%.•The treatment allows filling the ...pores and fractures with compatible compounds.•The treatment allows restoring the appearance of the original material.
The vast majority of building materials that are heavily affected by salts require desalination and subsequent consolidation treatments. This double intervention entails a risk associated with the loss of material due to continuous contact with the affected surface. This study evaluates the effectiveness of an electrokinetic process of simultaneous desalination-consolidation of two types of stones (dolostone and limestone). The results show that it is possible to reduce the salts up to percentages of 100% and at the same time to fill the pores and fractures with insoluble compounds compatible with the materials to be treated, such as calcium-magnesium carbonates.
•Ten years of irrigation with brackish water resulted in a less SOC-rich soil.•The soil microbial communities in the Brackish field were less connected and more stressed.•The correlations of soil ...microbial hub species with soluble salts were ion-specific.
Irrigation with brackish water has been widely applied in many regions of the world as an efficient alternative to conserve freshwater resources. Although it has limited soluble salt content, brackish water can alter the physio-chemical properties and microbial communities of soil over time. In this study, a cotton field that utilized drip irrigation with brackish water for 10 years (Brackish field) was compared with a nearby field that utilized drip irrigation with fresh water (Fresh field). Our results show the following: 1) After 10 years, the Brackish field was saltier with a greater electrical conductivity and sodium adsorption ratio, as well as less soil organic carbon content when compared with the Fresh field. 2) The more polarized distribution of the most abundant operational taxonomic unit (OTU) was observed in the Brackish field, accompanied by significantly smaller beta diversity, a less clustered network and fewer co-occurrences (edges) within the soil microbial community compared with the less salty Fresh field, altogether demonstrating that long-term brackish irrigation was very likely to form a less diverse and more stressed environment for soil microbes to co-exist. 3) The mismatches between the edge ranking of hub species and the ranking of relative abundances highlight that the predominant abundances of salt tolerant species from genera Acinetobacter and Pseudomonas may help cotton to grow better in the saline soil but may not help to stabilize soil microbial communities. In future studies, sophisticated sampling protocols with high time-resolution are required to fully capture the possible soil microbial responses to event-sensitive ion redistributions across cotton rows as well during repeated irrigation cycles.
Nitrate and ammonium are common inorganic contaminants of anthropogenic origin in many shallow aquifers around the world, while nitrite is less common, but it is most harmful than nitrate and ...ammonium due to its high reactivity. This paper presents evidence of nitrite accumulation after intense rainfalls in soil samples collected in an agricultural field characterized by organic matter chronic depletion. Moreover, an intact core from the same site was also collected to perform an unsaturated column experiment (60 cm long and 20 cm outer diameter) mimicking heavy rainfalls (230 mm in 2 days). Results from the field site showed nitrite accumulation (up to 0.45 mmol/kg) at 50–70 cm depth, just below the plough layer. The column experiment showed very high initial concentrations of nitrate and nitrite in the leachate and a progressive decrease of nitrate due to denitrification. The numerical flow model was calibrated versus the observed volumetric water contents and leachate flow rates. The numerical reactive transport model was calibrated versus the leachate concentrations of six dissolved species (ammonium, nitrate, nitrite, dissolved organic carbon, chloride and bromide). The optimized model resulted to be robustly calibrated providing insights on the kinetic rates driving the production, accumulation and leakage of nitrite, showing that incomplete denitrification is the source of nitrite. As far as the authors are aware, this is the first study reporting a clear link between high nitrite leaching rates and extreme rainfall events in lowland agricultural soils depleted in organic matter. The proposed methodology could be applied to quantify nitrite cycling processes in many other agricultural areas of the world affected by extreme rainfall events.
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•Field monitoring was unable to give insights on NO2− accumulation.•Column experiments were unavoidable to truthfully describe NO2− fate.•Soluble salts were dissolved and leached by intense rainfalls.•Partial nitrification and denitrification produced a transient NO2− accumulation.•Droughts followed by extreme rainfalls will trigger NO2− leaching to groundwater.
•A byzantine church affected by rising damp was investigated by an integrated approach.•The church is below the water table and a continuous pumping system is operating.•Materials, moisture amount, ...salts, soil and indoor/outdoor climate were analyzed.•The monitoring lasted 2 years and allowed to study the phenomenon of rising damp.•The effect of an accidental flooding event was included in the investigation.
Monitoring rising damp in historic masonry buildings requires an integrated approach, including not only the quantification of moisture in materials over time, but also the investigation of the supply of water from the ground, the evaporative capacity of the surrounding air, and the presence of potentially hygroscopic salts. However, this approach is seldom applied, hence our knowledge of the phenomenon of rising damp in real historic masonry structures is often only partial. In this paper, the proposed approach was applied to the church of Santa Croce in Ravenna, Italy, an outstanding example of masonry building affected by rising damp and related materials’ deterioration. Santa Croce is a Byzantine church surrounded by an archaeological site and the whole area is presently located under the water table level, requiring a continuously operating pumping system to prevent the flooding of the entire zone. The testing and monitoring of moisture and salts in the church’s materials started in September 2020 and is presently running. The data collected so far are presented and discussed in this paper, providing a contribution to a better understanding of this phenomenon. Moreover, during the monitoring period, a pumping system failure caused the flooding of the area in the period August-November 2021, allowing to investigate the impact of this event on the moisture in the materials. The protocol of testing described in this paper may provide a promising and effective method to investigate rising damp and is a starting point in view of its mitigation.
The present work aims to provide a comprehensive review of the experimental studies focusing on municipal solid waste incineration fly-ash (FA) treatments that are required before the application of ...advanced processes aimed at their final reuse or safe disposal. The investigated pre-treatments are divided into three categories: (1) water washing/chemical leaching; (2) electrodialysis; and (3) thermal separation. Analysed aspects include: (1) process efficiency; (2) effect on FA physical–chemical characteristics; and (3) process applicability as a function of secondary FA treatment steps which are generally required for final disposal or reuse of the remediated waste. Investigations related to these elements allows a determination of the efficacy and the operational convenience of a specific pre-treatment to achieve a proper FA remediation level. A comparison of studies in the literature provides a thorough source and a useful basis for correctly addressing future experimental activities and research efforts. The discussion of the results provides the basis for the development of a suitable methodology to optimize the environmentally sustainable reuse or safer disposal of treated FA.
Appalachian USA surface coal mines face public and regulatory pressure to reduce total dissolved solids (TDS) in discharge waters, primarily due to effects on sensitive macroinvertebrates. Specific ...conductance (SC) is an accurate surrogate for TDS and relatively low levels of SC (300–500 μS cm−1) have been proposed as regulatory benchmarks for instream water quality. Discharge levels of TDS from regional coal mines are frequently >1000 μS cm−1. The primary objectives of this study were to (a) determine the effect of rock type and weathering status on SC leaching potentials for a wide range of regional mine spoils; (b) to relate leachate SC from laboratory columns to actual measured discharge SC from field sites; and (c) determine effective rapid lab analyses for SC prediction of overburden materials. We correlated laboratory unsaturated column leaching results for 39 overburden materials with a range of static lab parameters such as total-S, saturated paste SC, and neutralization potential. We also compared column data with available field leaching and valley fill discharge SC data. Leachate SC is strongly related to rock type and pre-disturbance weathering. Fine-textured and non-weathered strata generally produced higher SC and pose greater TDS risk. High-S black shales produced the highest leachate SC. Lab columns generated similar range and overall SC decay response to field observations within 5–10 leaching cycles, while actual reduction in SC in the field occurs over years to decades. Initial peak SC can be reliably predicted (R2 > 0.850; p < 0.001) by simple lab saturated paste or 1:2 spoil:water SC procedures, but predictions of longer-term SC levels are less reliable and deserve further study. Overall TDS release risk can be accurately predicted by a combination of rock type + S content, weathering extent, and simple rapid SC lab measurements.
•TDS leaching risk was evaluated for 39 rock spoils from 3 Appalachian USA coal mining states.•Materials were evaluated by lab leaching and static analyses and compared with field results.•Rock type and pre-mine weathering extent have dominant influences on TDS risk.•Peak TDS (specific conductance) was accurately predicted (R2 > 0.8) by saturated paste extracts.•Overall TDS risk is accurately predicted by rock type, weathering, total-S and paste conductance.
Release of total dissolved solids (TDS) to streams in the Appalachian USA coalfields is reliably predicted by simple lab saturated paste conductance, rock type and weathering extent.
•The firing temperature of sewage sludge ash (SSA) affects the brick properties.•The best results were obtained with mixed-in SSA fired at 900 °C.•The soluble salts level rises with SSA addition but ...remains within allowed limits.•Higher firing temperatures reduce the soluble salts level in the bricks.
The influence of combustion temperature on the properties of sewage sludge ash (SSA) as a substitute material for the production of fired clay bricks was studied. The experiments were performed with sewage sludge (SS) from wastewater treatment plants (WWTP) in Zagreb (ZG) and Karlovac (KA). SS samples were fired at temperatures of 800, 900 and 1000 °C, and the properties of the resulting SSA were determined and compared with clay and SS. Bricks with 5 wt% SSA as clay substitute were prepared and compared with clay bricks (control). SSA bricks produced at higher temperatures are of higher strengths and lower water absorption, which are both desirable properties. Compressive strength tests showed that SSA obtained at a firing temperature of 900 °C is the most suitable for use in bricks. For the first time, the influence of SSA on the content of soluble salts in bricks was tested. The content of soluble salts, expressed by the electrical conductivity of leachate, in SSA bricks showed increased values compared to the control bricks, which were 2.8 and 4.6 times higher in bricks with SSA produced at 800 °C. Still, bricks with SSA prepared at higher temperatures had lower content of soluble salts and also SSA from KA had lower soluble salts content than SSA from ZG. The total amount of Na+, K+, Mg2+ in all bricks made with SSA was below the limits for category S2 according to EN 771-1.
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•O-Alkylated resorcinarenes have eight easily transformable ester or alkynyl groups.•The octaester gave conjugates with benzyl- and phenethylamines.•The CuAAC of azides to ...alkynyl-resorcinarene introduced triazole groups into molecules.•Water-soluble salts and complexes with biologically active amines were obtained.
Derivatives containing eight easily transformable ester (2) or alkynyl (3) groups were prepared by the alkylation of rctt ortho-methyl-tetra-C-naphthyl-resorcinarene 1 with ethyl 2-bromoacetate and propargyl bromide. Amination of compound 2 gave conjugates (5, 6) of resorcinarenes with biologically active benzyl- and phenethylamines. The reactions proceeded most efficiently in a microwave reactor. The catalytic cycloaddition of benzyl azide or ethyl azidoacetate to octaalkynyl-resorcinarene 3 was used to prepare rctt resorcinarenes (7, 8) conjugated to eight triazole moieties. Resorcinarene 2 is easily converted to octacarboxy derivative (4), which reacts with ethanolamine and phenethylamine to give water-soluble salts (9, 10), whereas reactions with benzylamine and tryptamine result in the formation of complexes (11, 12) containing several amine groups arranged in space in different ways.
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