Rock Powder Research Articles

An image segmentation-based method for quantifying the rock failure mechanism under true triaxial compression

Understanding the impact of geostress on the failure mechanism of surrounding rock is necessary for underground engineering applications. Here, we carried out a series of true triaxial tests on sandstone . The mechanisms of the areas on the fracture surface that appear in different colors are identified. Using the image segmentation method , the white shear fracture area on the grayscale image of the fracture surface is extracted. By calculating the proportion of the white shear fracture area, the rock failure parameter S for quantifying the rock failure mechanism is defined, and the influences of σ 2 and σ 3 on rock failure mechanisms are analyzed. Moreover, a criterion for determining the failure mechanism of rock under true triaxial stress is established. The results indicate that the shear fracture area that appears white is due to the adherence of rock debris and powder on the surface. The rock failure parameter S is appropriate to quantify the rock failure mechanism. A larger S indicates a higher proportion of shear fracture in the rock failure. The increase in σ 3 has a significant promotional effect on the development of the shear fracture. An increase in σ 2 can effectively promote the initiation of tensile fracture. According to the criterion, once the σ 2 and σ 3 of the stress environment are clarified, the failure mechanism of the rock can be predicted. This work contributes to an improved understanding of the failure mechanism of rock and a potential means by which to guide the design and construction of underground engineering.

Estimating technological parameters and stem productivity of sugarcane treated with rock powder using a proximal spectroradiometer Vis-NIR-SWIR

This study aimed to evaluate the use of proximal Vis-NIR-SWIR spectroscopy to estimate technological parameters and tons of sugarcane per hectare (TSH) with the application of rock powder to the soil. It was carried out in an Arenosol area in Paranavaí , Brazil. The treatments were arranged within a split-plot system, designed in randomized blocks with four repetitions. For the experimental plots, inputs supplying calcium, magnesium, and sulfur were applied, whereas inputs supplying potassium were used for the subplots. The first and second cycles (sugarcane) were completed at 14 and 26 months, respectively, after the inputs application. During both growth cycles, technological parameters of the crop and of the TSH were determined. In addition, the stem spectrum of the crop was collected with a Vis-NIR-SWIR proximal spectroradiometer for later prediction of the parameters and TSH through the Partial Least Square Regression technique. It was possible to adjust models in the prediction phase with R 2 p > 0.50 and RPD p > 1.50 for all evaluated attributes, with emphasis on three variables, namely purity, reducing sugars, and brix, which had R 2 p and RPD p values above 0.86 and 2.75, respectively. The results show that proximal Vis-NIR-SWIR spectroscopy can be used to predict technological parameters and TSH of sugarcane with the application of rock powder. It offers advantages in relation to usual methods, since it is less time-consuming and low-cost, moreover it does not involve the use of toxic reagents. • The application of rock powders enabled a wide diversity of spectral curves. • Technological parameters and sugarcane yield can be quantified by Vis-NIR-SWIR spectroscopy. • The SWIR region was important for the construction of the PLSR model. • Vis-NIR-SWIR spectroscopy is presented as an alternative to the analyses of sugarcane.

Determination of Ultra‐Trace Au, Ag, As, Pt and Re Mass Fractions in Volcanic Glasses and Rock Powders by LA‐ICP‐MS

Practical methods for determining the ultra‐trace abundances of precious metals in geological materials are needed for research into magmatic and hydrothermal processes and to expand the geochemical footprints of concealed ore deposits. This study presents a new protocol for determining Au, Ag, As, Pt and Re mass fractions in both volcanic glasses and in rock powders prepared as nano‐powder pellets, through the synthesis and refinement of published LA‐ICP‐MS methods. This matrix flexibility allows the method and its limitations to be rigorously assessed for the first time using different volcanic materials. High‐yield laser parameters, interference corrections and low oxide production rates facilitated by laser ablation sampling enabled accurate measurements without chemical pre‐separation. A key finding is that ablation‐remobilised system contamination must be quantified and corrected to make accurate ng g−1‐level Au determinations by LA‐ICP‐MS, resulting in a mean + 2s quantification limit for Au of 0.38 ng g−1. This approach is likely necessary for other ultra‐trace LA‐ICP‐MS analyses of certain elements. Following this correction, the protocol can be usefully applied to both in situ analysis of volcanic materials and efficiently integrated into methods for the determination of major and trace elements in nano‐powder pellets.

The Adsorptive and Photocatalytic Performance of Granite and Basalt Waste in the Discoloration of Basic Dye

The present work explored the adsorptive capacity and catalytic activity of rock powders from basaltic and granitic rocks in the discoloration of synthetic and industrial effluents containing the yellow dye Basic Yellow 96. The rock powders were characterized with scanning electron microscopy associated with energy-dispersive spectroscopy, photoacoustic spectroscopy, N2 physisorption and X-ray diffraction, the latter confirming the abundant presence of silica in the four materials studied. The basaltic powders presented specific surface areas between 7 and 10 times greater than those of granitic materials, which allowed up to 92% removal of the dye in 3 h of test using the basaltic powder. Despite the smaller area, the granitic materials showed considerable photocatalytic activity in 3 h, 94%, the same as that of the basaltic materials in the photocatalysis. Granitic and basaltic photocatalysts proved to be efficient in the discoloration of synthetic and industrial effluents, although TOC analyses indicated that it was not possible to promote the pollutant mineralization in the industrial effluent. Both artificial light and sunlight were effective in the photocatalysis of the dye, although the former was slightly faster.

Destabilization of carbon in tropical peatlands by enhanced weathering

Enhanced weathering is a carbon dioxide (CO2) removal strategy that accelerates the CO2 uptake and removal from the atmosphere by weathering via the dispersion of rock powder. Warm and humid conditions enhance weathering and among the suggested target areas for enhanced weathering are tropical peatlands. However, the effect of enhanced weathering on peatland carbon stocks is poorly understood. Here, we present estimates for the response of CO2 emissions from tropical peat soils, rivers and coastal waters to changing soil acidity induced by enhanced weathering application. We estimate that the potential carbon uptake associated with enhanced weathering is reduced by 18–60% by land-based re-emission of CO2 and is potentially offset completely by emissions from coastal waters. Our findings suggest that in contrast to the desired impact, enhanced weathering may destabilize the natural carbon cycle in tropical peatlands that act as important carbon sinks and protect against coastal erosion.

The Effectiveness of Using Coral Stone and Shell Powder as Natural Coagulants in Reducing Mn, Fe and Turbidity Levels in Water Using the Backwash Method

Turbidity poses a big problem in water treatment. One of the processing stages in the water treatment unit is the coagulation/flocculation process to remove turbidity. This study uses coral stone and oyster shell powder as locally available natural coagulants to reduce water turbidity. Coral stone and shell powder have now been widely used as a natural coagulant in reducing Mn, Fe levels. However, using coral stone and shell powder as a natural coagulant is still debated. To determine the effectiveness of using coral stone and shellfish powder as natural coagulants in reducing Mn, Fe, and water turbidity levels using the backwashing method. This research is an experimental study with a pretest and post-test design. The population in this study was all water in community dug wells that were cloudy and contained high levels of Mn, Fe, and a sample of 100 liters was taken for filtering experiments and samples for checking levels of Mn, iron (Fe), and water turbidity. This research was conducted at the Health Polytechnic of the Aceh Ministry of Health from July to November 2021. The water analysis was carried out at the Health Laboratory of the Aceh Environmental Health Department. The laboratory tests were analyzed using the paired t-test and the ANOVA test. The results showed an effect of the treatment of coral stone and clamshells on the decrease in Fe content with a P-value of 0.012 (α < 0.05). Likewise, the Mn content affects the treatment of coral stone and shell powder with a thickness of 40 cm, 30 cm, and 20 cm, which affects the decrease in Mn content with a P-value of 0.001 (α < 0.05). The results showed that Fe levels before entering the shelter had a significant difference with the processing of coral and shell powder with a thickness of 40 cm, 30 cm, and 20 cm. Coral and shells with a thickness of 40 cm, 30 cm, and 20 cm with 15 repetitions can reduce Fe content from 5.2476 ppm to the lowest at 2.4747 ppm. Coral Rock and Shell Powder Effective as a ........

Rock-cutting and wear performance of a novel TBM disc cutter with spiral grooves

Tunnel boring machines (TBMs) require a large thrust and suffer from extensive cutter wear when tunneling in hard rock stratum. Controlling the cutter-rock contact by using an appropriate contact surface design can potentially improve the cutting performance of TBM cutters. This paper proposes a design scheme of disc cutters with surface grooves and uses a hybrid discrete element model and a reduced-scale rock-cutting experiment to evaluate the cutting performance of the proposed cutter. The results show that at the same penetration depth, the cutting force required by the grooved cutters is lower than that of the conventional flat-top cutter, and the rock chip volume decrease is not significant. Thus, the rock-cutting specific energy is reduced. The grooved cutter has a discontinuous contact area with the rock, reducing the volume of the crushed zone and the rock powder; thus, less energy is required for rock cutting. Wear experiments are performed to evaluate the durability of the proposed cutter. The results indicate that the tooth tips of the spiral groove cutter suffer plastic deformation in the first several hundred cycles, leading to a larger diameter decrease than that of the flat-top cutter. However, the two cutters have similar wear rates after the run-in period, and adhesive wear is the dominant wear mechanism of both cutters. This study demonstrates the feasibility of improving the cutter performance by changing the surface structure, providing a new strategy for increasing the driving speed of TBMs in a hard rock stratum.

Determination of Scandium (Sc), Yttrium (Y), and Rare-Earth Elements (REEs) in Mafic and Ultramafic Rock Powder by a Modified and Validated Digestion Protocol and Inductively Coupled Plasma – Mass Spectrometry (ICP-MS)

The global demand for rare earth elements (REEs) has been associated with the increased use of renewable energy technologies. However, due to the low occurrence of REEs in economic sources, such as geologic samples, it is essential to employ suitable sample preparation methods and measurement techniques that allow for reliable quantification. While acid digestion procedures have been conventionally used to free metals from silicate rocks, few studies have evaluated these methods for quantitative measurement of REEs, including Sc and Y in mafic-ultramafic rocks. This study involves validating a modified digestion procedure to facilitate the determination of Sc, Y, and REEs in mafic-ultramafic matrices. Three reference materials (RMs) (OKUM, BHVO-1, and JB-1a) were used to assess the performance of this modified method. The calculated percent error (< 10%) for most elements was in good agreement with the reference values, except La in OKUM, Er in BHVO-I, and Eu, Gd, Tb, Ho, and Er in JB-1a. The precision of the modified method was satisfactory, with values generally below 5%. The smooth chondrite normalized REE patterns indicate good quality data. The t-values of the studied elements were lower than the t-critical value (± 12.71), suggesting no significant differences between the analytical and Intertek values. Thus, the modified method could be used as a viable alternative in determining REEs in Ni laterite samples by ICP-MS.

Wavelet Energy Evolution Characteristics of Acoustic Emission Signal under True-Triaxial Loading during the Rockburst Test

The rockburst simulation test is conducted by utilizing a mineral-containing marble specimen. The loading condition is set to the three directions, each loading on five surfaces except for a single free surface. The whole test procedure is monitored in real time by using a PCI-II acoustic emission monitoring system and a high-speed camera. According to the test outcomes, rockburst is a process in which energy is rapidly released from the free surface. Rock block and rock plate are buckled and ejected from the free surface and a severe rockburst process is accompanied by spray rock powder. An explosion sound can be heard during the process, which can be analyzed by signal processing techniques. The failure mode of the specimen is a splitting-shearing composite failure, and the free surface becomes a rockburst destruction surface. A V-type rockburst pit is formed in the ejection area. The effective acoustic emission signal of the whole test process is decomposed and reconstructed using five-layer wavelets to produce six frequency band sub-signals. In addition, the wavelet energy and its energy distribution coefficients are assessed for various frequency bands, and the proportion of each dominant frequency band within each period is computed. Finally, it was found that the dominant frequency band is 125~250 kHz, while the suboptimal frequency band is 250~500 kHz. The succeeding features are noticed to be used as predicted features for the rockburst disaster. Namely, acoustic emission signals arise in large numbers and the energy distribution coefficient of the dominant frequency band concentrates above 0.4. The proportion of dominant frequency band appears in continuous valley type and keeps below 80%, while the proportion of suboptimal frequency band appears in continuous peak type and keeps above 20%.

Stabilization and Ecological Risk Evaluation of Heavy Metals in Farmland Soils by Addition of Attapulgite Modified with Phosphates

Purpose. Attapulgite was modified by sodium dihydrogen phosphate, oxalic acid-activated phosphate rock powder, potassium dihydrogen phosphate, calcium superphosphate, ammonium dihydrogen phosphate, and fused calcium-magnesium phosphate and used in the remediation of Cd, Zn, and Ni. Materials and Methods. Attapulgite was modified by six kinds of phosphate (ratio: 1 : 2), and the improvement effect of passivation material on soil polluted by cadmium, zinc, and nickel was determined. CaCl2-extractable and toxicity characteristic leaching procedure- (TCLP-) extractable Cd, Zn, and Ni were measured in order to estimate the bioavailability and the stabilization efficiency. Pot experiment was conducted to study the enrichment and transport ability of Cd, Zn, and Ni in corn. The ecological risk and ecological toxicity of soil environment were evaluated by calculating SEm, ERIm, CRIm, and BUF. Results and Discussion. Compared with ATP, passivation materials AAPR, AMRP, ASSP, AMAP, and AFMP can improve the stability of CD, Zn, and Ni in soil, and AAPR has the best effect. Compared with CK treatments and ATP treatments, the concentrations of TCLP-extractable Cd decreased by 30.80% and 24.72%, respectively, the concentrations of TCLP-extractable Zn decreased by 15.50% and 11.18%, respectively, and the concentrations of TCLP-extractable Ni decreased by 31.34% and 23.20%, respectively. Compared with ATP treatments, CRI, BUF-Cd, BUF-Ni, and BUF-Zn decreased by 24.67%, 52.88%, 78.73%, and 41.18%, respectively, in the AAPR treatments. Conclusions. Phosphate-modified attapulgite can effectively improve the stability of heavy metals in soil and reduce the migration of heavy metals. In the soil polluted by Cd, Zn, and Ni, the passivation effect of AAPR is the best. Therefore, AAPR can be used as an economical, safe, and effective passivation material to improve Cd-, Zn-, and Ni-contaminated soil, which would have a high utilization value in field applications.

Nutrient transfer in rangelands under rock powder amendment

AbstractBackgroundNative pasture yields are soil nutrient limited in subtropical regions. The use of powdered rock as a soil amendment is increasing in these regions as it can supply plant nutrients, increasing the yield of pasture in traditional livestock farming systems. Although powdered rock may also be useful to preserve native rangelands, little is known about the nutrient dynamics in rangeland soil–plant systems amended with powdered rock.AimsWe evaluated the chemical characteristics of an Acrisol and the grassland production treated with different rates of hydrothermalized basalt powder (HBP) to estimate the nutrient transfer from soil to plants in a rangeland.MethodsDifferent HBP doses (0, 1, 2, 4, and 8 t ha−1) were applied twice to the native rangeland topsoil, to which soluble fertilizer was never applied. Soil and plant samples were collected and chemically evaluated seven times over 2 years (674 days).ResultsThe soil copper (Cu) and potassium (K) contents increased with the HBP dose, while the available phosphorus (P) and potential acidity (H+Al) decreased. The soil pH temporarily increased. The HBP doses did not affect the exchangeable calcium (Ca), magnesium (Mg), or aluminum (Al) contents. The nutrient concentrations in plant dry mass tended to increase for P, K, Ca, and Mg due to the transfer from the soil. The shoot dry mass increased with the HBP dose according to the growth season of the pasture.ConclusionThese findings suggest that application of HBP improves the soil‐native pasture system by the transfer of nutrients from soil to plants and by increasing dry mass yield. Rock powder application in native pastures (low chemical fertility and acid conditions) is a feasible agronomic alternative for increasing pasture yield with low impact on the system.

Enhanced weathering potentials—the role of in situ CO2 and grain size distribution

The application of rock powder on agricultural land to ameliorate soils and remove carbon dioxide (CO2) from the air by chemical weathering is still subject to many uncertainties. To elucidate the effects of grain size distribution and soil partial pressure of carbon dioxide (pCO2) levels on CO2 uptake rates, two simple column experiments were designed and filled nearly daily with an amount of water that simulates humid tropical conditions, which prevail in areas known for being hotspots of weathering. Multiple materials (dunite, basanite, agricultural oxisol, a combination of the latter two, and loess) were compared under ambient and 100% CO2 atmosphere. In a second series, single material columns (dunite) were filled with three different grain size distributions. Total alkalinity, pH, major ions, and dissolved silica were determined in the outflow water of the columns for about 300 days. Under ambient atmospheric conditions, the CO2 consumption was the lowest in the oxisol column, with 100 t CO2 km−2 year−1, while dunite and basanite showed similar consumption rates (around 220 t CO2 km−2 year−1). The values are comparable to high literature values for ultramafic lithologies. Interestingly, the mixture of basanite and oxisol has a much higher consumption rate (around 430 t CO2 km−2 year−1) than the basanite alone. The weathering fluxes under saturated CO2 conditions are about four times higher in all columns, except the dunite column, where fluxes are increased by a factor of more than eleven. Grain size distribution differences also play a role, with the highest grain surface area normalized weathering rates observed in the columns with coarser grains, which at first seems counterintuitive. Our findings point to some important issues to be considered in future experiments and a potential rollout of EW as a carbon dioxide removal method. Only in theory do small grain sizes of the spread-material yield higher CO2 drawdown potentials than coarser material. The hydrologic conditions, which determine the residence times in the pore space, i.e., the time available for weathering reactions, can be more important than small grain size. Saturated-CO2 column results provide an upper limit for weathering rates under elevated CO2.

The use of Vis-NIR-SWIR spectroscopy in the prediction of soil available ions after application of rock powder

Some of the problems attributed to traditional laboratory analyses that limit the correct assessment of the nutrient contents in the soil are time requirements and high cost of the soil nutrient determinations. To solve these problems, a study was carried out to evaluate the use of visible, near-infrared, and short-wave infrared (Vis-NIR-SWIR) spectroscopy in the prediction of soil available ions submitted to the application of rock powders. The study was carried out on an Arenosol in Paranavaí City/Brazil. Treatments (rock powders) were arranged within a split-plot system designed in randomized blocks with four repetitions. Sugarcane was cultivated for 14 months after the application of rock powders. Later, 96 soil samples were collected for measuring the pH and available ions P, K+, Ca2+, Mg2+, S-SO42-, Si, Cu2+, Fe2+, Mn2+, and Zn2+ as well as spectral reading through a Vis-NIR-SWIR spectroradiometer to predict the soil chemical attributes through the partial least square regression (PLS) technique. The results showed that the elements K+, Ca2+, Mg2+, Cu2+, and Fe2+ could be predicted with a reasonable rightness degree (R2p > 0.50, RPDp > 1.40) from spectral models. However, for the attributes pH, P, S-SO42-, Si, Mn2+, and Zn2+, there were no satisfactory models (R2p < 0.50, RPDp < 1.40). Thus, the application of rock powder changed the spectral curves and, because of that, allows the building of PLS models to predict the elements K+, Ca2+, Mg2+, Cu2+, and Fe2+. Therefore, Vis-NIR-SWIR spectroscopy is a promising alternative to the routine analyses of soil fertility since it has advantages such as fast analytical speed, low cost, easy to operate, non-destructive, and environmentally friendly, because it does not use harmful chemicals.

Mineralogical analysis of rock dust for remineralization of soil intended for pasture

The objective of this study was to verify the effects of rock dust on the soil of an area destined for pasture. Mineralogical analysis of the rock dust was performed using X-ray diffraction, and the major oxides and minor elements were analyzed using X-ray fluorescence. The soil samples were analyzed according to PROFERT-MG. The following were identified from the X-ray diffractogram of the total rock powder: quartz (43.66%), albite (38.10%), microcline (15.30%), and muscovite (1.80%). Regarding the major elements, SiO2 (81.92%), Al2O3 (11.04%), and Na2O (3.86%) were predominant, and an important amount of K2O (2.61%) was present. In the chemical characterization of the soil, an increase in the levels of P, K, Ca, Mg, Sb, t, V, organic matter, and organic carbon were observed with the addition of rock dust. A comparison of the chemical analysis results with the CONAMA quality reference values indicated that the rock dust sample had acceptable levels with respect to the quality reference for all analyzed heavy metals. In a comparative analysis with MAPA's Normative Instruction No. 5/2016, it was found that rock dust does not fully comply with the minimum requirements of the legislation. In full compliance with the IN from chemical analysis, it had a minimum required content of at least 1% for K2O. Preliminary studies have indicated that the application of this material as a remineralizer has potential, mainly in relation to the supply of K2O. However, physical adjustments are required in the beneficiation process to comply with the standards.

Collection and Processing of Behavioural Data of the Olive Fruit Fly, Bactrocera oleae, When Exposed to Olive Twigs Treated with Different Commercial Products

The need for the development of sustainable control methods of herbivorous insects implies that new molecules are proposed on the market. Among the different effects the new products may have on the target species, the alteration of insect oviposition behaviour might be considered. At the scope, parallel simple behavioural assays can be conducted in arena. Freely available software can be used to track observed events, but they often need intensive customization to the specific experimental design. Hence, integrating such software with, e.g., R environment, can provide a much more effective protocol development for data collection and analysis. Here we present a dataset and protocol for processing data of the oviposition behaviour of the olive fruit fly, Bactrocera oleae, when exposed to olive twigs treated with different commercial products. Treatments were rock powder, propolis, a mixture of rock powder and propolis, copper oxychloride, copper sulphate, and water as the experimental control. JWatcher was used to simultaneously collect data from 12 arena assays and ad-hoc developed R code was used to process raw data for data analyses. The procedure described here is novel and represents a valuable and transferable protocol to analyse observational events in B. oleae, as well as other biological systems.

Recycling of isabgol (Plantago ovata Forsk.) straw biomass and mineral powder with bio-inoculants as an effective soil amendment for isabgol cultivation

Efficient utilization of isabgol ( Plantgo ovata Forsk.) straw biomass through preparation of bio-active organic fertilizer in a natural composting process has not been studied. In this study, phosphate rock and silicate mineral (mica) powder were used as natural sources of phosphorus (P) and potassium (K), respectively. Cow dung slurry as a natural decomposer was mixed with the straw biomass at a 10:1 (weight/weight) ratio along with mineral powder. Then, nutrient-mobilizing bio-inoculants were used in the composting process after attaining thermal stabilization. The agronomic effectiveness of the resulting bio-active compost (BAC) as a bio-organic fertilizer was compared with that of conventional organics (farmyard manure and vermicompost) and chemical fertilizer (CF) by growing isabgol under field conditions. Composting with the natural sources of P and K along with the bio-inoculants increased the total nitrogen (13.6 g kg -1 ), P (38.7 g kg -1 ), and K (31.2 g kg -1 ) contents in the final product ( i.e ., BAC) compared with composting without the mineral powder and bio-inoculants. Application of BAC remarkably improved the seed yield (2.5%) and husk quality of isabgol in comparison with conventional organics and CF. Compared with CF, BAC significantly boosted the economic yield of isabgol by improving the husk recovery (2.5%) and mucilage yield (4.12%). Furthermore, BAC significantly improved the soil quality by increasing organic carbon (C), available nutrients, and microbial biomass C contents, as well as enzyme activity. The positive correlation between soil and plant parameters also highlighted the benefits of BAC for isabgol production through soil quality improvement. Therefore, it can be considered as a zero-waste technology, whereby a large quantity of straw biomass generated from isabgol cultivation, which contains essential nutrients, can be recycled back to the soil. Furthermore, BAC can be effectively used as a bio-active organic fertilizer, particularly in systems where chemical inputs are restricted, such as organic agriculture.

Can co-application of silicate rock powder and humic-like acids increase nutrient uptake and plant growth in weathered tropical soil?

ABSTRACT Silicate rock powder (SRP) restores the fertility of weathered soils. However, its slow nutrient release is a disadvantage for short-duration crops. Humic-like acids (HLAs) are plant biostimulants that enhance root development and nutrient uptake. This work evaluates the effects of the co-application of HLA extracted from a vermicompost and SRP on the nutrient uptake and growth of maize cultivated in weathered soil in Brazil. The chemical composition of HLA was assessed using Fourier-transform infrared spectroscopy and 13Carbon-nuclear magnetic resonance, revealing an overall characteristic of hydrophobicity. A preliminary trial with different HLA concentrations (0, 20, 40, 80, and 160 mg L−1) revealed that 40 mg L−1 HLA resulted in the highest increase in the root area, dry root weight, H+ efflux, and the number of lateral roots, compared with other concentrations. The main experiment using soil treated with SRP at different rates (0, 600, 1200, 1800, and 2400 kg ha−1) showed that the co-application of SRP and HLA caused a significant difference in the root and total plant weights, compared with the sole SRP application. Furthermore, it increased the nutrient content of the plants. These effects are mainly because of increased proton pump activity and the hydrophobicity of HLA.

Adsorption of Pollutants from Liquid Swine Manure Through the Application of Metabasalt Rock Powder

Adequate animal manure disposal became a challenge in agriculture. Liquid swine waste (LSW), easily used in agriculture, presents disadvantages due to the high volume and low nutrient concentrations. Metabasalt powder, a residue of amethyst mining, was evaluated as an adsorbent agent of nutrients (Cu, Zn, P, and K) from LSW. Seven doses of metabasalt powder were tested in proportion with LSW (0, 4, 10, 20, 40, 80, and 160 kg m−3), and during four contact times (CT) (9, 21, 42, and 84 days) and ions were dosed in the liquid and solid fractions. Copper and phosphorus concentrations in the liquid fraction were lower at 21 days of contact. The lowest concentration of zinc in the liquid fraction was observed at the dose of 10 kg m−3 of metabasalt powder, and at 9 days of CT. The K concentrations in the liquid fraction diminished linearly with the metabasalt doses, in which the major dose presented 51% of K compared to the control. The application of metabasalt as an adsorbent agent reduced the contaminant charge in the liquid fraction of LSW, suggesting safe water disposal while promoting ion accumulation in the solid fraction. The use of metabasalt powder became a useful strategy to make LSW pre-treatment on-farm.

Enhanced Weathering Using Basalt Rock Powder: Carbon Sequestration, Co-benefits and Risks in a Mesocosm Study With Solanum tuberosum

Enhanced weathering (EW) of silicate rocks can remove CO2 from the atmosphere, while potentially delivering co-benefits for agriculture (e.g., reduced nitrogen losses, increased yields). However, quantification of inorganic carbon sequestration through EW and potential risks in terms of heavy metal contamination have rarely been assessed. Here, we investigate EW in a mesocosm experiment with Solanum tuberosum growing on alkaline soil. Amendment with 50 t basalt/ha significantly increased alkalinity in soil pore water and in the leachate losses, indicating significant basalt weathering. We did not find a significant change in TIC, which was likely because the duration of the experiment (99 days) was too short for carbonate precipitation to become detectable. A 1D reactive transport model (PHREEQC) predicted 0.77 t CO2/ha sequestered over the 99 days of the experiment and 1.83 and 4.48 t CO2/ha after 1 and 5 years, respectively. Comparison of experimental and modeled cation pore water Mg concentrations at the onset of this experiment showed a factor three underestimation of Mg concentrations by the model and hence indicates an underestimation of modeled CO2 sequestration. Moreover, pore water Ca concentrations were underestimated, indicating that the calcite precipitation rate was overestimated by this model. Importantly, basalt amendment did not negatively affect potato growth and yield (which even tended to increase), despite increased Al availability in this alkaline soil. Soil and pore water Ni increased upon basalt addition, but Ni levels remained below regulatory environmental quality standards and Ni concentrations in leachates and plant tissues did not increase. Last, basalt amendment significantly decreased nitrogen leaching, indicating the potential for EW to provide benefits for agriculture and for the environment.

Mineralogy and geochemical signatures as indicators of differential weathering in natural soil profiles from the West Asturian-Leonese Zone (NW Iberia)

This paper presents detailed mineralogical results together with a geochemical characterization for a sequence of six natural soil profiles. Bedrock samples (R series) and overlying soil samples (S series) were characterized. The soil profiles are distributed in a series of Paleozoic lithological units from lower Ordovician to upper Carboniferous in age (Iberian Massif, NW Iberia). The lithological influence on mineral properties and geochemical composition and, how different weathering may be occurring under very similar temperate and acidic conditions, have been studied. Field observations together with laboratory analyses were indicative of differential weathering. So, a series of selected chemical indices and relations were applied to clarify this assumption. The mineralogy was analysed by Scanning electron microscopy (SEM-EDS), X-ray diffraction (XRD) of rock powder and soil oriented aggregates. X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectroscopy (ICP-MS) were applied to analyse chemical composition. The first results showed how major elements, SiO2, Al2O3 and Fe2O3, slightly enriched in the soil profiles, are consistent with the dominant mineralogy: quartz, chlorite, muscovite and/or illite, together with kaolinite and albite. The bases K2O, Na2O, CaO and MgO are also coherent with mineral composition and experience little variation, but are gradually removed in the profiles. The mobility of major elements leads to a general loss of bases and, in general, a slight enrichment in silica and sesquioxides. SiO2 is enriched, firstly accumulated in soils and partially depleted by dissolution as colloidal form. Al2O3 in some soils is slightly less than in former rocks, so other physical processes are expected to take place, involving clay removal with consequent aluminium depletion too. A special emphasis has been given to albite coexisting with kaolinite, firstly supposed to be directly inherited from parent substrates when present, but finally the chemical index PIA shows it was mainly due to mineral alteration of plagioclases. The best correlations to explain the albite alteration and kaolinitization progress were obtained with chemical indices PIA, CIW, CIA and Al2O3/Na2O ratio. This together with mineralogical signatures, suggest that kaolinite is the result of gradual dissolution due to the acid hydrolysis of albite in such acidic environments, which may also be attributed to the organic matter influence.