scholarly journals Toxic Elements in Soil and Rice in Ecuador

Agronomy ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1594
Author(s):  
Oliva Atiaga ◽  
Jenny Ruales ◽  
Luís Miguel Nunes ◽  
Xosé Luis Otero
Keyword(s):  
Toxic Elements ◽  
Total Content ◽  
Threshold Value ◽  
Soil Samples ◽  
Threshold Values ◽  
Bioconcentration Factors ◽  
Rice Plants ◽  
Geochemical Fractions ◽  
Bioavailable Fraction ◽  
International Regulations

The concentration of trace toxic metals (Cr, Zn, As, Pb, Cd, Cu, and Ni) in soil and rice plants, including the stems, leaves, and grain, from the main rice-producing provinces in Ecuador, was determined. Additionally, the soils were analyzed to determine their properties, composition, total content, bioavailable fraction, and geochemical fractions of toxic elements. Approximately 30% of soil samples in the case of Cr and Cu and 10% of samples in the case of Ni exceeded the legal thresholds for Ecuador. Moreover, for Cr and Cu, approximately 4% and 13% of samples, respectively, exceeded the threshold value of 100 mg kg−1 proposed for these two elements in several international regulations. Concentrations of As, Pb, and Cd in the soils were below the threshold values established both by Ecuadorian laws and by other countries. The concentrations of metals in rice plants did not correlate linearly with the total metal concentrations in the soil, nor with their bioavailability. However, the bioconcentration factors for As, Cd, Cu, Ni, and Zn could be predicted from bioavailability by a power law with exponents ranging from −0.724 to −1.625, which is typical of accumulator plants, where trace metal homeostasis plays an important role.

scholarly journals THE CONTENT OF LEAD IN SOILS OF ALLOTMENT GARDENS IN ZIELONA GÓRA, POLAND

2016 ◽  
Vol 48 (1) ◽  
pp. 41 ◽  
Author(s):  
Barbara Walczak ◽  
Jakub Kostecki ◽  
Róża Wasylewicz ◽  
Tomasz Lassota ◽  
Andrzej Greinert ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Reference Point ◽  
Total Content ◽  
Soil Samples ◽  
Lead Content ◽  
Threshold Values ◽  
Allotment Gardens ◽  
Living Organisms ◽  
Polish Law

<p>Lead, as a heavy metal, is harmful to living organisms (both plants and animals) and it is relatively mobile in the environment. In this article we present the results of the monitoring of the lead content in local allotment gardens (Zielona Góra, Poland). We examined both the total and the phytoavailable form. Soil samples were collected in eight places in the allotment gardens, and two places in the neighbourhood of the allotment gardens. The lead content in the soil met the Polish soil ground standards (Regulation by the Minister of the Environment of 9.09.2002). The total content of lead varied from 21 to 39 mg kg-1, (12–14 mg kg-1 at reference point) and the form potentially available for plants from 10 to 19 mg kg-1 (6–7 mg kg-1 at reference point). The content of lead does not exceed the threshold values according to Polish law.</p><p> </p><p>Ołów, jako metal ciężki, jest szkodliwy dla organizmów żywych (zarówno roślin jak i zwierząt) I jest względnie ruchliwy w środowisku. W pracy przedstawiono wyniki badań monitoringowych dot. zawartości ołowiu ogólnego oraz przyswajalnego w glebach ogródków działkowych Zielonej Góry. Próbki glebowe pobrano z 8 miejsc w obrębie ogrodów oraz z 2 miejsc referencyjnych zlokalizowanych w sąsiedztwie ogrodów. Zawartość ołowiu w glebach nie przekraczała wartości progowych wyznaczonych wg prawa polskiego, przyjętego w zarządzeniu Ministra Środowiska z dnia 9 września 2002 r. Zawartość ołowiu całkowitego wahała się od 21 do 39 mg kg-1, (12–14 mg kg-1 w punkcie referencyjnym) a ołowiu w formie potencjalnie dostępnej dla roślin od 10 do 19 mg kg-1 (6–7 mg kg-1 w punkcie referencyjnym).</p>

scholarly journals Soil and plant pollution by potentially toxic elements in Slovakia

2011 ◽  
Vol 51 (No. 6) ◽  
pp. 243-248 ◽  
Author(s):  
J. Kobza
Keyword(s):  
Toxic Elements ◽  
Soil Cover ◽  
Plant Biomass ◽  
Total Content ◽  
Measured Data ◽  
Potentially Toxic Elements ◽  
Soil Samples ◽  
Soil Monitoring ◽  
Polluted Soils ◽  
Plant Pollution

The Problem of soil and plant pollution by heavy metals in Slovakia is evaluated in this study. The measured data on the main risk elements have been obtained from a soil-monitoring grid in Slovakia, which consists of 318 agricultural sites. Analytical procedures of Cd, Pb, Cr, Ni, Zn, Cu (extracted by 2 mol/l HNO<sub>3</sub> and by 0.05 mol/l EDTA) as well as the total content of the described elements including Hg have been used for soil samples. Also the plants collected at the same sampling sites were analysed for their Cd, Pb, Cr and Hg contents. On the basis of the obtained results it may be concluded that significant pollution was determined only on 0.4% of the total soil cover in Slovakia. The significant correlation was determined between the soil available heavy metal content (extracted by 0.05 mol/l EDTA) and plant content. Potentially toxic elements were accumulated in the plant biomass only on heavily polluted soils

scholarly journals Geochemical Fractions of Heavy Metals in Bottom Sediments of the Pobeda Hydrothermal Field, Mid-Atlantic Ridge (17°07′–17°08′ N)

2021 ◽  
Vol 6 (1) ◽  
pp. 14
Author(s):  
Liudmila Demina ◽  
Irina Gablina ◽  
Olga Dara ◽  
Dmitry Budko ◽  
Nina Gorkova ◽  
...  
Keyword(s):  
Total Content ◽  
Element Distribution ◽  
Hydrothermal Field ◽  
Residual Fraction ◽  
Carbonate Sediments ◽  
Metalliferous Sediments ◽  
Geochemical Fractions ◽  
Metalliferous Sediment ◽  
Fe And Mn ◽  
Mid Atlantic Ridge

We examined the distribution of Fe, Mn, Cu, Zn, and Pb in one core of metalliferous, and one core of non-mineralized (background) carbonate sediments (located 69 km northwards), from the Pobeda hydrothermal field. Mechanisms of metal accumulation in sediments (12 samples) were evaluated based on sequential extraction of geochemical fractions, including mobile (exchangeable complex, authigenic Fe-Mn hydroxides, and sulfides), and lithogenic (fixed in crystalline lattices) forms. Maps of element distribution in sediment components were obtained using a scanning electron microscope equipped with an energy-dispersive spectrometry detector. In metalliferous sediments, according to X-ray diffraction data, the main Fe mineral phase was goethite FeOOH (37–44% on a carbonate-free basis). The contents of Fe and Mn reached 31.6 and 0.18%, respectively, whereas concentrations of Cu, Zn and Pb were 0.98, 0.36, and 0.059%. The coefficient of metal enrichment relative to background values varied from 16 to 125 times. The exception was Mn, for which no increased accumulation was recorded. Essential mass of Fe (up to 70% of total content) was represented by the residual fraction composed of crystallized goethite, aluminosilicates, the minerals derived from bedrock destruction processes. Among geochemically mobile fractions, 90–97% of total Fe was found in the form of authigenic oxyhydroxides. The same fraction was the predominant host for Mn in both metalliferous and background sediments (55–85%). A total of 40–96 % of Cd, Cu, Zn, and Pb were associated with these Fe and Mn fractions. The sulfide fraction amounted to roughly 10% of each metal. In metalliferous sediment core, the maximum concentrations of metals and their geochemically mobile fractions were recorded in deeper core intercepts, an observation that might be attributed to influence of hydrothermal diffused fluids. Our data suggested that metals are mostly accumulated in carbonate sediments in their contact zone with the underlying serpentinized basalts.

A Numerical Study of the Fixed-Threshold Criterion for Expressing Transient Stability Constraints in Optimal Power Flow

2015 ◽  
Vol 781 ◽  
pp. 379-383
Author(s):  
Warut Suampun
Keyword(s):  
Power Flow ◽  
Optimal Power Flow ◽  
Transient Stability ◽  
Numerical Study ◽  
Threshold Value ◽  
Computing System ◽  
Threshold Values ◽  
Optimal Power ◽  
Threshold Criterion ◽  
Fixed Threshold

A numerical study of the widely used fixed-threshold criterion for expressing transient stability constraints in optimal power flow (TSCOPF) is conducted. Based on a stability-region framework, a more accurate expression of transient stability constraint in TSCOPF is presented. A method for computing system exact threshold values is proposed and employed for the study of threshold values under different conditions. It is shown via numerical results on the WSCC9 and IEEE145 systems that the exact threshold value for each system and contingency is in fact not a constant, and can vary greatly depending on several factors such as types of contingency, loading conditions, and network topology.

scholarly journals Dinamika Amonium dan Nitrat Lahan Sawah Latosol pada Budidaya Konvensional Padi Lokal dan Hibrida di Subak Jatiluwih

2019 ◽  
Vol 9 (2) ◽  
pp. 135
Author(s):  
GITA YUNI PERMATASARI ◽  
ANAK AGUNG ISTRI KESUMADEWI ◽  
ANAK AGUNG NGURAH GEDE SUWASTIKA
Keyword(s):  
Hybrid Rice ◽  
Soil Samples ◽  
Rice Fields ◽  
Water Phase ◽  
Nitrate Content ◽  
Rice Plants ◽  
Nitrate Concentrations ◽  
Kjeldahl Method ◽  
The Times ◽  
Rice Water

Ammonium Dynamics and Latosol Wetland Nitrates in Conventional Cultivation of Local and Hybrid Rice in Jatiluwih Subak. Plants absorb nitrogen in the form of ammonium (NH4+) and nitrate (NO3-). Each sample was analyzed for its ammonium and nitrate levels using macro Kjeldahl method. The results showed that the concentration of ammonium and nitrate in soil of the two rice fields were similar. The ions contents were as following: nitrate (2,67%) and ammonium (2,67%) in local rice, while those in hybrid rice fields were amounted of 1,48% and 4,59% respectivelly. The concentration of ammonium and nitrate on 21 DAC in soil samples remained low and rose at 28 DAC, then decreased at 56 DAC. It means that the times of fertilizing always done by the farmers were not appropriate.The content of ammonium and nitrate in water phase much lower than that in soils for both types of rice plants. The highest concentration of ammonium in local rice fields was 0,093% at the time of tillage and the lowest 0% on 21 DAC, while the highest nitrate concentrations in local rice water was 0,37% at 70 DAC and the lowest was 0% at of 21 DAC. The highest ammonium concentrations in hybrid rice 0,33% at 14 DAC, and the lowest 0% at 42 HST, while the highest nitrate content 0,47% at 42 DAC and the lowest 0% at the time of tillage. The fertilizing times recommended based on the findings of this reaserch is at 10-15 DAC for both rice types and another subsquent fertilization on 60-65 DAC for local rice and 40-45 DAC in hybrid rice.

scholarly journals State of Heavy Metals Pollution of Flooded Agricultural Land in the North Part of Republic of Srpska

2017 ◽  
Vol 17 (1) ◽  
pp. 19
Author(s):  
Tihomir Predić ◽  
Petra Nikić Nauth ◽  
Bojana Radanović ◽  
Alen Predić
Keyword(s):  
Heavy Metals ◽  
Soil Contamination ◽  
Agricultural Land ◽  
Total Content ◽  
Soil Samples ◽  
Available Phosphorus ◽  
The North ◽  
North Part ◽  
Grid Points ◽  
Phosphorus And Potassium

This paper presents the results of the research of soil contamination in flooded area located at the confluence of Bosna and Sava rivers. The sampling was performed according to a network of points Etrs89 reference European Network based on grid points of 500 m x 500 m. The total number of soil samples was 31 and 13 samples of sediment-mud. In the soil samples and sediment-mud samples various parameters were analyzed: pH H2O and 1 M KCl, humus (method by Tjurin), and the readily available phosphorus and potassium (AL method). The interpretation of total content of heavy metals in the soil was conducted according to Dutch Soil Remediation Circular (2009). The samples were analyzed for the total content of heavy metals: Pb, Cd, Cr, Ni, Zn, Cu (aqua regia digestion, AAS) and the elevated concentrations of Ni. However, Ni content in mud was from 240.5 mg/kg to 294.5 mg/kg, in soil it was from 128.9 mg/kg to 452.1 mg/kg. All mud samples were alkaline, and 79% of soil samples were alkaline and of neutral reaction. The analysis indicated that the flood in May 2014 was not caused by soil contamination with heavy metals, which however contributed to the increase of the overall content of these elements in the soil.

Measuring Environmental Favorability for Tropical Cyclogenesis by Statistical Analysis of Threshold Parameters

2011 ◽  
Vol 24 (23) ◽  
pp. 5968-5997 ◽  
Author(s):  
Michael G. McGauley ◽  
David S. Nolan
Keyword(s):  
Tropical Cyclone ◽  
Threshold Value ◽  
New Method ◽  
Tropical Cyclogenesis ◽  
Tropical Cyclone Genesis ◽  
Threshold Values ◽  
Reanalysis Dataset ◽  
Statistical Probability ◽  
Saturation Deficit ◽  
Meteorological Features

Abstract As the climate changes, the ability to predict changes in the frequency of tropical cyclogenesis is becoming of increasing interest. A unique approach is proposed that utilizes threshold values in potential intensity, wind shear, vorticity, and normalized saturation deficit. Prior statistical methods generally involve creating an index or equation based on averages of important meteorological parameters for a given region. The new method assumes that threshold values exist for each important parameter for which cyclogenesis is unlikely to develop. This technique is distinct from previous approaches that seek to determine how each of these parameters interdependently favors cyclogenesis. To determine three of the individual threshold values (shear, potential intensity, and vorticity), an idealized climate is first established that represents the most advantageous but realistic (MABR) environment. An initial numerical simulation of tropical cyclone genesis in the MABR environment confirms that it is highly favorable for cyclogenesis. Subsequent numerical simulations vary each parameter individually until no tropical cyclone develops, thereby determining the three threshold values. The new method of point downscaling, whereby background meteorological features are represented by a single vertical profile, is used in the simulations to greatly simplify the approach. The remaining threshold parameter (normalized saturation deficit) is determined by analyzing the climatological record and choosing a value that is statistically observed to prevent cyclogenesis. Once each threshold value is determined, the fraction of time each is exceeded in the location of interest is computed from the reanalysis dataset. The product of each fraction for each of the relevant parameters then gives a statistical probability as to the likelihood of cyclogenesis. For predicting regional and monthly variations in frequency of genesis, this approach is shown to generally meet or exceed the predictive skills of earlier statistical attempts with some failure only during several off-season months. This method also provides a more intuitive rationale of the results.

Value of intravoxel incoherent motion for differential diagnosis of renal tumors

2018 ◽  
Vol 60 (3) ◽  
pp. 382-387 ◽  
Author(s):  
Qingqiang Zhu ◽  
Wenrong Zhu ◽  
Jing Ye ◽  
Jingtao Wu ◽  
Wenxin Chen ◽  
...  
Keyword(s):  
Renal Cell ◽  
Clear Cell ◽  
Threshold Value ◽  
Intravoxel Incoherent Motion ◽  
Renal Tumors ◽  
Threshold Values ◽  
Renal Cell Carcinomas ◽  
Perfusion Fraction ◽  
D Values ◽  
Tumor Types

Background Few studies have reported on the use of intravoxel incoherent motion (IVIM) for renal tumors. Purpose To investigate the value of IVIM for distinguishing renal tumors. Material and Methods Thirty-one patients with clear cell renal cell carcinomas (CCRCCs), 13 patients with renal angiomyolipomas with minimal fat (RAMFs), eight patients with chromophobe renal cell carcinomas (ChRCCs), and ten patients with papillary renal cell carcinomas (PRCCs) were examined. The tissue diffusivity (D), pseudodiffusivity (D*), and perfusion fraction (f) were calculated. Results The D and f values were highest for CCRCCs, lowest for PRCCs, and intermediate for ChRCCs and RAMFs ( P < 0.05). The D values of CCRCCs differed significantly from those of ChRCCs and PRCCs ( P < 0.05). The D* values were highest for RAMFs, lowest for ChRCCs, and intermediate for CCRCCs and PRCCs ( P < 0.05). Statistically significant differences were observed between the D* values of CCRCCs and RAMFs ( P < 0.05). The D* values of the CCRCCs differed significantly from the D* values of the ChRCCs ( P < 0.05). Using the D and f values of 1.10 and 0.41, respectively, as the threshold values for differentiating CCRCCs from RAMFs, ChRCCs, and PRCCs, the best results had sensitivities of 81.0% and 66.8% and specificities of 85.7% and 81.0%, respectively. Using the D* value of 0.038 as the threshold value for differentiating RAMFs from CCRCCs, ChRCCs, and PRCCs, the best result obtained had a sensitivity of 90.5% and specificity of 76.2%. Conclusion IVIM may provide information for differentiating renal tumor types.

scholarly journals A Simplified Approach for the Annual and Spatial Evaluation of the Comfort Classes of Daylight Glare Using Vertical Illuminances

Buildings ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 171 ◽  
Author(s):  
Luigi Giovannini ◽  
Fabio Favoino ◽  
Valerio Lo Verso ◽  
Anna Pellegrino ◽  
Valentina Serra
Keyword(s):  
Case Studies ◽  
Grid Point ◽  
Threshold Value ◽  
Average Error ◽  
Threshold Values ◽  
Simplified Approach ◽  
Annual Basis ◽  
Venetian Blinds ◽  
Simplified Method

A simplified approach to calculate the daylight glare comfort class (imperceptible, perceptible, disturbing, or intolerable glare) on annual basis and for a grid of points in a space is presented. This method relies on the calculation of the vertical illuminance (Ev) for each grid point only, which is compared to an Ev threshold value for each daylight glare comfort class. These Ev threshold values are determined through a comparison with the Daylight Glare Probability (DGP) values on an annual basis through a fault-detection technique, for a reduced number of points. Compared to an annual calculation of exact DGP values on a certain grid, this approach is able to evaluate the daylight glare comfort classes only, but it is less time consuming. The paper presents and critically discusses this simplified method by means of its application to different case-studies: south and west oriented office in Turin (Lat 45.1° N), in which the DGP is assessed for three points in the space, considering glazing with different transmission properties (specular or scattering) and visible transmittances, as well as three operable internal shading systems (one venetian blinds and two roller blinds, for solar or glare control). For the presented case studies, the average error in the classification of the space according to daylight glare comfort classes is below 5% when comparing this simplified approach to related DGP values.

scholarly journals CO<sub>3</sub><sup>2−</sup> concentration and pCO<sub>2</sub> thresholds for calcification and dissolution on the Molokai reef flat, Hawaii

2006 ◽  
Vol 3 (3) ◽  
pp. 357-369 ◽  
Author(s):  
K. K. Yates ◽  
R. B. Halley
Keyword(s):  
Reef Flat ◽  
Threshold Value ◽  
Published Data ◽  
Carbonate Sediments ◽  
Threshold Values ◽  
Coral Rubble ◽  
The Impact ◽  
Substrate Types ◽  
Atmospheric Pco2

Abstract. The severity of the impact of elevated atmospheric pCO2 to coral reef ecosystems depends, in part, on how seawater pCO2 affects the balance between calcification and dissolution of carbonate sediments. Presently, there are insufficient published data that relate concentrations of pCO2 and CO32− to in situ rates of reef calcification in natural settings to accurately predict the impact of elevated atmospheric pCO2 on calcification and dissolution processes. Rates of net calcification and dissolution, CO32− concentrations, and pCO2 were measured, in situ, on patch reefs, bare sand, and coral rubble on the Molokai reef flat in Hawaii. Rates of calcification ranged from 0.03 to 2.30 mmol CaCO3 m−2 h−1 and dissolution ranged from –0.05 to –3.3 mmol CaCO3 m−2 h−1. Calcification and dissolution varied diurnally with net calcification primarily occurring during the day and net dissolution occurring at night. These data were used to calculate threshold values for pCO2 and CO32− at which rates of calcification and dissolution are equivalent. Results indicate that calcification and dissolution are linearly correlated with both CO32− and pCO2. Threshold pCO2 and CO32− values for individual substrate types showed considerable variation. The average pCO2 threshold value for all substrate types was 654±195 μatm and ranged from 467 to 1003 μatm. The average CO32− threshold value was 152±24 μmol kg−1, ranging from 113 to 184 μmol kg−1. Ambient seawater measurements of pCO2 and CO32− indicate that CO32− and pCO2 threshold values for all substrate types were both exceeded, simultaneously, 13% of the time at present day atmospheric pCO2 concentrations. It is predicted that atmospheric pCO2 will exceed the average pCO2 threshold value for calcification and dissolution on the Molokai reef flat by the year 2100.

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