scholarly journals Properties of humic acids from copper tailings 20 years after reclamation

2020 ◽  
Vol 85 (3) ◽  
pp. 407-419
Author(s):  
Svjetlana Radmanovic ◽  
Mirjana Markovic ◽  
Uros Jovanovic ◽  
Maja Gajic-Kvascev ◽  
Djuro Cokesa ◽  
...  
Keyword(s):  
Humic Acids ◽  
Type B ◽  
Arable Soils ◽  
Copper Tailings ◽  
Litter Input ◽  
Top Soil ◽  
Humification Degree ◽  
Sol Stability ◽  
Over Time ◽  
Control Samples

Part of Cu post flotation tailings of Serbia ZiJin Bor Copper, Serbia, was reclaimed by restoration of top soil with arable soils, and revegetation in 1991. Humic acids isolated from these Technosols were investigated to find out if their properties underwent any changes since reclamation. Two groups of control samples were used. Elemental composition (CHNS analysis) falls within the range of average soil humic acids. Humic acids belong to the type B pointing out to its lower humification degree (UV?Vis). Relative abundances of functional groups are ranged as follows: polysaccharide C ??aromatic C > carboxyl C > OH group > aliphatic C. Aromaticity indexes are low, 1.88? 3.25 (ATR-FTIR). Basic units at pH 10 are in the 11.7?26.8 nm range. Pronounced reaggregation (1462-?5218 nm) at pH 3 points out to less expressed humic acid sol stability, as well as to increase in aromatic condensation degree (dynamic light scattering). No significant changes have occurred in technosol humic acids since the recultivation, confirming stability of their properties over time (PCA). Nevertheless, humic acids from very strongly acidic Technosols show higher humifycation degree possibly originating from arable soils used in reclamation, but more likely from low soil pH and low litter input, results of unsuccessful reclamation.

Changes in the Humic Acid–Metal Complexation Characteristics Depending on Humification Degree / Humīnskābju – Metālu Kompleksveidošanās Rakstura Izmaiņas Atkarībā No Humifikācijas Pakāpes

2012 ◽  
Vol 51 (3) ◽  
pp. 228-237
Author(s):  
D. Dudare ◽  
M. Klavins
Keyword(s):  
Humic Acid ◽  
Stability Constants ◽  
Humic Acids ◽  
Complex Stability ◽  
Peat Layer ◽  
Raised Bog ◽  
Complexing Capacity ◽  
Humification Degree ◽  
Complexation Process ◽  
Complex Stability Constants

The aim of this study is to determine the Cu(II) complexing capacity and stability constants of Cu(II) complexes of humic acids isolated from two well-characterized raised bog peat profiles in respect to the basic properties and humification characteristics of the studied peats and their humic acids. The complex stability constants significantly change within the studied bog profiles and are well correlated with the age and decomposition degree of the peat layer from which the humic acids have been isolated. Among factors that influence this complexation process, molecular mass and ability to form micellar structures (supramolecules) of humic substances are of key importance.

scholarly journals The influence of biochar on the content of carbon and the chemical transformations of fallow and grassland humic acids

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marta Cybulak ◽  
Zofia Sokołowska ◽  
Patrycja Boguta
Keyword(s):  
Humic Acids ◽  
Chemical Properties ◽  
Soil Samples ◽  
Low Molecular Weight ◽  
Organic Carbon Content ◽  
Chemical Transformations ◽  
Limited Information ◽  
Grassland Soils ◽  
Low Degree ◽  
Humification Degree

AbstractThere is limited information regarding the effect of biochar (BioC) on the fertility of fallow and grassland soils, as well as on the properties of their humic acids (HAs). The objective of this study was to evaluate with a 3-year field experiment the influence of BioC on the organic matter (OM) in Haplic Luvisol. BioC (obtained via wood waste pyrolysis at 650 °C) was applied to the soil of subplots under fallow and grassland at doses of 0, 1, 2 and 3 kg m−2. The soil samples were collected eight times. The physicochemical properties were determined for the soil and BioC by analysing the density, pH, surface charge, ash, and organic carbon content. Based on the changes in the structure of the HAs and their quantity in the soils, the chemical properties of the HAs were determined. The maximum BioC dose caused an increase in the content of Corg and HAs. BioC did not influence the humification degree coefficients of the HAs originated from fallow, whereas in the grassland, there were significant changes observed in these coefficient values, indicating that BioC may stimulate and accelerate the humification process of soil HAs. Increasing the BioC doses caused an increase in the soil’s HA content, suggesting an increase in soil sorption capacity. The fluorescence data showed BioC addition to the soil caused an increase in the number of structures characterised by low molecular weight and a low degree of humification.

scholarly journals The effectiveness of TiO2 additions to mortar to maintain initial conditions in terms of its reflectance to solar radiation

2017 ◽  
Vol 17 (3) ◽  
pp. 39-56 ◽  
Author(s):  
Sérgio Roberto Andrade Dantas ◽  
Fulvio Vittorino ◽  
Kai Loh
Keyword(s):  
Solar Radiation ◽  
Ultraviolet Radiation ◽  
Initial Conditions ◽  
Type A ◽  
Just Noticeable Difference ◽  
Type B ◽  
Climate Conditions ◽  
Type D ◽  
Type C ◽  
Over Time

Abstract Contact of facades with degradation agents and direct incidence of ultraviolet radiation on external coatings make them more opaque over time, affecting their colour and reflectance characteristics. This study evaluated the effect of adding different TiO2 contents to mortars applied in concrete substrates in order to verify the reflectance maintenance on surfaces after exposure over time. Mortar with different concentrations of TiO2 (1%, 5%, 10%) were produced in relation to the total dry premix, added as a powder and compared to unpainted mortar without TiO2 (type "A") and painted mortar without TiO2 (type "B"), both used as a reference for colour and reflectance. Exposed over 16 months to climate conditions in São Paulo, regarding the maintenance of reflectance and solar radiation, the results showed that type "B" (0%TiO2) painted mortar presented the best performance. Type "C" (1%TiO2) and type "D" (5%TiO2) unpainted mortar remained more stable. Type "A" (0%TiO2) and type "E" (10%TiO2) unpainted mortar showed greater differences according to the Just Noticeable Difference (JND) range caused by dirt pick up.

scholarly journals Spatial distribution of top soil water content in an experimental catchment of Southeast Brazil

2011 ◽  
Vol 68 (3) ◽  
pp. 285-294 ◽  
Author(s):  
Carlos Rogério de Mello ◽  
Léo Fernandes Ávila ◽  
Lloyd Darrell Norton ◽  
Antônio Marciano da Silva ◽  
José Márcio de Mello ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Standard Deviation ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain Reflectometry ◽  
Water Infiltration ◽  
Local Factor ◽  
Top Soil ◽  
Over Time

Soil water content is essential to understand the hydrological cycle. It controls the surface runoff generation, water infiltration, soil evaporation and plant transpiration. This work aims to analyze the spatial distribution of top soil water content and to characterize the spatial mean and standard deviation of top soil water content over time in an experimental catchment located in the Mantiqueira Range region, state of Minas Gerais, Brazil. Measurements of top soil water content were carried out every 15 days, between May/2007 and May/2008. Using time-domain reflectometry (TDR) equipment, 69 points were sampled in the top 0.2 m of the soil profile. Geostatistical procedures were applied in all steps of the study. First, the spatial continuity was evaluated, and the experimental semi-variogram was modeled. For the development of top soil water content maps over time a co-kriging procedure was used having the slope as a secondary variable. Rainfall regime controlled the top soil water content during the wet season. Land use was also another fundamental local factor. The spatial standard deviation had low values under dry conditions, and high values under wet conditions. Thus, more variability occurs under wet conditions.

Comparative characterization of humic acids from arable soils of the taiga, steppe, and semidesert zones

2012 ◽  
Vol 45 (11) ◽  
pp. 1033-1041 ◽  
Author(s):  
G. V. Motuzova ◽  
H. M. Derham ◽  
A. A. Stepanov
Keyword(s):  
Humic Acids ◽  
Arable Soils ◽  
Comparative Characterization

scholarly journals Greenhouse Gas Emission Model for Tidal Flats in the Republic of Korea

2021 ◽  
Vol 9 (11) ◽  
pp. 1181
Author(s):  
Nhi Yen Thi Dang ◽  
Heung-Sik Park ◽  
Kaleem Anwar Mir ◽  
Choong-Gon Kim ◽  
Seungdo Kim
Keyword(s):  
Greenhouse Gas Emission ◽  
Ghg Emissions ◽  
Tidal Flats ◽  
Mitigation Strategies ◽  
Future Climate Change ◽  
Emission Model ◽  
Top Soil ◽  
Ghg Reduction ◽  
The Republic ◽  
Over Time

Since coastal wetlands have been severely degraded and polluted by human activities, they have increasingly become a significant source of greenhouse gases (GHGs), so understanding the characteristics of their emissions is critical for devising future climate change mitigation strategies. This study modified a model based on carbon balance to forecast carbon stored and CO2, CH4 emissions in four types of typical tidal flats—Phragmites australis (PA), Spartina alterniflora (SA), Suaeda japonica (SJ), and Bare Tidal Flat (BTF) in Korea’s Ganghwa province from 2017 to 2047. The model was built using biomass data from salt plant species collected in different locations. The results indicate that the total annual simulated flow of CH4 increased over time in all four areas, most notably in SA, while CO2 remained relatively stable. The mean CO2 and CH4 fluxes in the four types of representative tidal flats were in the range of 0.03 to 19.1 mg m−2 d−1 and 0.007 to 5.23 mg m−2 d−1, respectively, across all seasons. Besides, the results indicate that the amount of carbon accumulated in the top soil increases linearly over time in nearly all areas studied, ranging from 0.01 to 0.13 (kgC m−2 yr−1). In general, the study provides a model for Korean tidal flats that incorporates carbon storage and GHG emissions in the intertidal zone in order to develop potential GHG reduction scenarios.

Abstract 20003: A 15-year Analysis and Descriptive Study of the Incidence, Clinical Characteristics, Management, and Outcomes of Lower Limb Ischemia in Type A and Type B Aortic Dissection Patients: Insights From the International Registry of Acute Aortic Dissection

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Susan Alaei ◽  
Thoralf M Sundt ◽  
Udo Sechtem ◽  
Truls Myrmel ◽  
Marco Di Eusanio ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
Lower Limb ◽  
Acute Aortic Dissection ◽  
Limb Ischemia ◽  
Type A ◽  
Leg Pain ◽  
Type B ◽  
Lower Limb Ischemia ◽  
Over Time ◽  
Overall Mortality

Background: This study assessed the incidence of lower limb ischemia as well as trends in management and outcomes while examining acute aortic dissection patients over a period of 15 years. Additionally, differences in clinical presentation, interventions performed, and mortality between patients with and without lower limb ischemia were investigated. Methods: Lower limb ischemia (LLI) was evaluated among 3812 patients enrolled in the International Registry of Acute Aortic Dissection over a 15-year period that was separated into three 5-year intervals: 1996-2001, 2002-2007, and 2008-2012. The cohort was then divided by dissection type and presence or absence of LLI. Results: Type A patients presenting with limb ischemia (N=280, 11.4%) were much more likely to have atherosclerosis (p=0.021) and to present with back, abdominal and leg pain versus chest pain (p<0.001 unless noted). Other symptoms of malperfusion, including ischemic spinal cord damage (p<0.001) and coma/altered consciousness (p=0.006) were more common in patients presenting with LLI. Surgery was less commonly performed in Type A LLI patients (79.3% vs 86.1%, p=0.002), a difference that did not change over time (p=0.453, trend p=0.479). Additionally, overall mortality was higher in LLI patients (37.5% vs 22.9%, p<0.001) and did not show improvement among the LLI cohort over time. Type B patients with LLI (N=102, 7.5%) were more likely to be current smokers (p=0.028), to present febrile (p=0.022), and to have leg pain (p<0.001). As with Type A, ischemic spinal cord damage was more common in the LLI cohort (p<0.001). Patients with LLI were much more likely to be managed with endovascular therapy (19.6% vs 50.0%, p<0.001) than with medication alone (66.5% vs 29.4%, p<0.001), with endovascular repair increasing in LLI patients over time (p=0.008, trend p=0.002). Again, overall mortality was higher in the LLI cohort (24.5% vs 9.7%, p<0.001) and did not change over time. Conclusions: Although Type B patients with LLI received more endovascular procedures in later years, overall mortality did not improve. Increased complications and higher mortality in the LLI cohort suggests a need for better monitoring and increased implementation of interventions in this population.

Influence of Extracorporeal Membrane Oxygenation Circuit on Nutritional Supplements

2020 ◽  
Vol 3 (5) ◽  
pp. 01-09
Author(s):  
AS Thiara
Keyword(s):  
Vitamin A ◽  
Extracorporeal Membrane Oxygenation ◽  
Ex Vivo ◽  
Nutritional Supplements ◽  
Ecmo Support ◽  
Blood Pump ◽  
Ecmo Circuit ◽  
Membrane Oxygenation ◽  
Over Time ◽  
Control Samples

Background The main function of extracorporeal membrane oxygenation (ECMO) is to provide systemic perfusion and gas exchange for patients with severe, acute respiratory or cardiac illness. The ECMO system consists of blood pump and a membrane oxygenator. ECMO oxygenator fibers, blood pump and tubing may bind circulating compounds such as drugs and nutritional components during ECMO support. Any loss of vital nutrients due to adsorption to the ECMO circuits may lead to further nutritional debilitation in critical ill patients. Objective The purpose of study is to analyze the amount of nutritional supplements adsorbed to the ECMO circuit under controlled ex vivo conditions Methods Six identical ECMO circuits were primed with fresh human whole blood and maintained under physiological conditions at 36°C for 24 hours. A dose of nutritional supplement calculated for a 70 kg patient was added. 150 mL volume was drawn from priming bag for control samples and kept under similar conditions. Blood samples were obtained at predetermined time points and analyzed for concentrations of vitamins, minerals, lipids, and proteins. Statistical analyses were performed using mixed models with robust standard errors, which allows for repeated samples within each setup and incomplete data. Results No significant differences were found between the ECMO circuits and controls for any of the measured variables: cobalamin, folate, vitamin A, glucose, concentration of minerals, HDL cholesterol, LDL cholesterol, total cholesterol, triglycerides, and total proteins. There was an initial decrease and then and increase in the concentration of cobalamin and folate. Vitamin A concentrations decreased in both groups over time. There was a decrease in concentration of glucose and an increased concentration of lactate dehydrogenase over time in both groups. Conclusion There were no changes in the concentrations of nutritional supplements in an ex vivo ECMO circuit compared to control samples, indicating that parenteral nutrition can be given during ECMO support. However, the time span of this study was limited, and the design made it impossible to investigate any functional and structural changes over time in nutritional supplements which lead to diminished effects through the ECMO circuit.

Effects of afforestation with Eucalyptus grandis on soil physicochemical and microbiological properties

Soil Research ◽  
2012 ◽  
Vol 50 (2) ◽  
pp. 167 ◽  
Author(s):  
Danju Zhang ◽  
Jian Zhang ◽  
Wanqin Yang ◽  
Fuzhong Wu
Keyword(s):  
Soil Fertility ◽  
Soil Properties ◽  
Agricultural Land ◽  
Soil Layer ◽  
Western China ◽  
Stand Age ◽  
Arable Soils ◽  
Total N ◽  
Over Time ◽  
Microbiological Properties

It is generally believed that plantations of Eucalyptus bring about a decrease in soil fertility. Soil physicochemical and microbiological properties were measured across a range of E. grandis plantation ages (1–10 years) in south-western China to determine whether and how eucalypt afforestation of agricultural land affected the soil fertility. The results indicate that afforestation with E. grandis caused changes in soil properties with soil depth, and the changes were dependent on the stand age. Soil bulk density decreased significantly, but water-holding capacity increased significantly with time. Soil organic matter content, C : N ratio, and soil microbial biomass C and N concentrations showed an initial phase of decline and then increased significantly over time in the upper soil layers of E. grandis plantations aged from 1 to 4 or 5 years. Soil pH in E. grandis plantations did not change significantly with stand age or soil layer. Cation exchange capacity in the upper soil layer of E. grandis plantations increased significantly over time. Total exchangeable bases and base saturation in the soil decreased significantly with depth and with increasing plantation age. Furthermore, E. grandis afforestation of arable soils had no significant effects on total N, total P, and available P contents. The requirements of the trees, understory microenvironmental conditions, and allelopathic effects might play important roles in the dynamic changes of soil physicochemical and microbiological properties. The results demonstrate the progressive development of processes that lead to the restoration of soil fertility following E. grandis afforestation of arable soils. However, most of the properties measured for the afforested soils resembled the properties of arable soils and did not resemble those of the soil of control forests. Thus, reversion of soil properties in the study plantations is likely to require a considerable period of time. Long-term research is needed to understand changes in the soil properties resulting from afforestation with Eucalyptus and to predict future trends.

scholarly journals Stand age and tree species affect N<sub>2</sub>O and CH<sub>4</sub> exchange from afforested soils

2011 ◽  
Vol 8 (9) ◽  
pp. 2535-2546 ◽  
Author(s):  
J. R. Christiansen ◽  
P. Gundersen
Keyword(s):  
Norway Spruce ◽  
Tree Species ◽  
Agricultural Land ◽  
Species Difference ◽  
N2o Emission ◽  
Stand Age ◽  
N Availability ◽  
N2o Production ◽  
Top Soil ◽  
Over Time

Abstract. Afforestation of former agricultural land is a means to mitigate anthropogenic greenhouse gas emissions. The objectives of this study were (1) to assess the effect of oak (Quercus robur) and Norway spruce (Picea abies [L.] Karst.) stands of different stand ages (13–17 and 40 years after afforestation, respectively) on N2O and CH4 exchange from the soil under these species and (2) identify the environmental factors responsible for the differences in gas exchange between tree species of different ages. N2O and CH4 fluxes (mean ± SE) were measured for two years at an afforested site. No species difference was documented for N2O emission (oak: 4.2 ± 0.7 μg N2O-N m−2 h−1, spruce: 4.0 ± 1 μg N2O-N m−2 h−1) but the youngest stands (1.9 ± 0.3 μg N2O-N m−2 h−1) emitted significantly less N2O than older stands (6.3 ± 1.2 μg N2O-N m−2 h−1). CH4 exchange did not differ significantly between tree species (oak: −8.9 ± 0.9, spruce: −7.7 ± 1) or stand age (young: −7.3 ± 0.9 μg CH4-C m−2 h−1, old: −9.4 ± 1 μg CH4-C m−2 h−1) but interacted significantly; CH4 oxidation in the soil increased with stand age in oak and decreased with age for soils under Norway spruce. We conclude that the exchange of N2O and CH4 from the forest soil undergoes a quick and significant transition in the first four decades after planting in both oak and Norway spruce. These changes are related to (1) increased soil N availability over time as a result of less demand for N by trees in turn facilitating higher N2O production in older stands and (2) decreasing bulk density and increased gas diffusivity in the top soil over time facilitating better exchange of N2O and CH4 with the atmosphere.

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