leaching potential
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Author(s):  
Ana P. da Silva ◽  
Ricardo F. Marques ◽  
Antônio C. da Silva Junior ◽  
Sidnei R. de Marchi ◽  
Dagoberto Martins

ABSTRACT Information about the impact of herbicides in the soil based on the growth of bioindicator species is extremely useful in developing crop management strategies. Therefore, this study aims to evaluate the leaching potential of the herbicide S-metolachlor under different natural precipitations in medium-textured Oxisol using bioindicator plants. A completely randomized experimental design was adopted, with four replicates and treatments arranged in a 3 × 8 factorial scheme [three indexes of precipitation occurred in the environment before the collection of the samples (50, 91, and 131 mm) and eight depths in the soil profile (0-0.03; 0.03-0.06; 0.06-0.09; 0.09-0.12; 0.12-0.15; 0.15-0.20; 0.20-0.25; 0.25-0.30 m)]. PVC columns were used, maintaining the original soil integrity during sampling after accumulating the stipulated natural precipitation. Longitudinal sections separated the columns to sow the bioindicator species (cucumber, lettuce, Alexander grass, and sorghum). The phytotoxicity symptoms of bioindicator plants were evaluated, adopting a phytotoxicity visual scale between 0 and 100%, at 5, 7, 9, and 11 days after seeding. The responses of the bioindicator species to the residual effect of the herbicide S-metolachlor were variable and depended on the rainfall level. Generally, in a medium-textured Oxisol, the higher values of concentration of S-metolachlor occurs in depths ranging between 0 and 0.06 m. The maximum leaching depth detected was 0.12-0.15 m with 131 mm of precipitation. Cucumber was the most sensitive species to the presence of S-metolachlor in an Oxisol of medium-texture since it presents symptoms of phytotoxicity at higher depths.


Author(s):  
Ali Ekhlasi Nia ◽  
Harrison Bull ◽  
Mohsen Asadi ◽  
Kerry McPhedran

Wastewater stabilization ponds (WSPs) are commonly used to reduce wastewater metal(loid) concentrations from drinking water treatment plants (DWTPs) through sedimentation. However, this results in increased sediment concentrations that can be released back into the overlying water. Thus, our goal was to evaluate the WSP metal(loid)s occurrence and leaching potential. Currently, a Saskatchewan based DWTP’s WSP system was investigated given historically elevated effluent As and Fe concentrations. The WSP consists of five ponds that were sampled on six occasions in 2019 and 2020. In addition, sediments were used in laboratory-based experiments to determine their leaching potential. Overall, the sediments were found to contain elevated concentrations of As and Fe with 25 to 400 and 10,000 to 45,000 mg/kg, respectively. Leaching experiments indicated that the pond sediments could potentially release As and Fe with log Kd values ranging from 2.21 to 4.31 L/kg, while Fe ranged from 3.32 to 5.53 L/kg.


2021 ◽  
Vol 11 (23) ◽  
pp. 11338
Author(s):  
Leidy Rendón-Castrillón ◽  
Margarita Ramírez-Carmona ◽  
Carlos Ocampo-López ◽  
Luis Gómez-Arroyave

Scaling up bioprocesses from the experimental to the pilot or industrial scale involves heuristics and scale relationships that are far from the specific phenomena and are usually not connected to the experimental data. In complex systems, the scaling-up methodology must connect the experimental data with the tools of engineering design. In this work, a two-stage gold bioleaching process was used as a case study to develop a mathematical model of bioprocess scaling that combines the design of experiments with dimensional analysis using the Buckingham Pi theorem to formulate a predictive model that allows scaling up bioprocesses. It was found that the C/N, C/K, and T/C ratios are dimensionless factors that can explain the behavior of a system. Using the Pearson Product–Moment bivariate analysis, it was found that the dimensionless factors C/N and C/K were correlated with the leaching potential of the fermented broth at 1060 cm−1. With these results, a non-linear logarithmic model based on dimensionless parameters was proposed to explain the behavior of the system with a correlation coefficient of R2 = 0.9889, showing that the optimal conditions to produce fermented broth comprised a C/N ratio close to 50 and a C/K ratio close to 800, which allows predicting the scaling of the bioprocess.


2021 ◽  
Vol 232 (11) ◽  
Author(s):  
Marina Aliste ◽  
Gabriel Pérez-Lucas ◽  
Isabel Garrido ◽  
José Fenoll ◽  
Simón Navarro

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Ali Huddin Ibrahim ◽  
Mohd Rosli Mohd Hasan ◽  
Ashiru Sani ◽  
Sharvin Poovaneshvaran ◽  
Tracy Leh Xin Wong ◽  
...  

Industrial solid waste has been widely used as an alternative additive for bituminous material modification. This study aims to evaluate the basic properties and quantify the leaching potential of modified asphalt binders incorporating crumb rubber powder (CRP) from waste tires and tin slag (TS) for a local smelting company. Three percentages of CRP and TS, at 5, 10, and 15%, were considered. The conventional asphalt binder (PEN 60/70), CRP, and TS-based modified asphalt binders were analyzed for toxicity, softening point, penetration value, elastic recovery, torsional recovery (TR), and coatability index. The findings indicated that the addition of the waste materials led to no significant heavy metal content in the asphalt binder mix. Moreover, the basic and physical properties of the asphalt binders were also improved by 5, 10, and 15% of the waste, respectively. However, TS waste exhibited limited effects on all the parameters and had a 5% optimum dosage. The modified binders’ results showed that the CRP modified asphalt binders had fewer heavy metals and responded more to elastic recovery and coatability.


Author(s):  
Friederike Meyer-Wolfarth ◽  
Elisabeth Oldenburg ◽  
Torsten Meiners ◽  
Katherine Muñoz ◽  
Stefan Schrader

AbstractA microcosm study was conducted at two different temperatures under laboratory conditions to investigate the regulatory capacity and the interactive performance of two soil fauna species (Aporrectodea caliginosa, earthworms, and Proisotoma minuta, collembolans) on the reduction of Fusarium toxins in contaminated maize stubbles. Single and mixed species treatments were exposed to artificially infected maize stubbles highly contaminated with the mycotoxins deoxynivalenol (DON) (10,462 µg kg−1) and zearalenone (ZEN) (2,780 µg kg−1) at 17 °C and 25 °C for time periods of 3 and 6 weeks. Immediately after the respective end of incubation, the microcosms were heavily watered to determine the leaching potential of DON and ZEN from contaminated maize stubbles. Maize residues, soil, and eluted water (percolate) samples were analysed for mycotoxin content using liquid chromatography coupled to mass spectrometry. The biomass of introduced earthworms and number of collembolans were monitored to get information about their adaptability to the experimental conditions. While the decline of ZEN was temperature-dependent, but not influenced by faunal activities, a reduction of DON due to faunal impact was observed by trend. In the leaching experiment, 67–82% of the DON content in the residual maize stubbles leached from the plant material by irrigation and was detected in the soil (1.9–3.4 µg kg−1) and in the percolate (12–295 µg L−1). In the case of ZEN, 27–50% of the mycotoxin leached from the residual maize stubbles due to watering but was only occasionally detected in traces in the soil and not found in the percolate. The results clearly reveal a leaching potential of both DON and ZEN, respectively, but a mobilisation with water was only observed for DON. Temperature confirmed to be a key factor, affecting the fate of the mycotoxins in the soil by driving the interaction between different soil fauna members as well as functional and trophic levels within the soil food web.


Chemosphere ◽  
2021 ◽  
Vol 273 ◽  
pp. 129644
Author(s):  
Haris Muhammad ◽  
Ting Wei ◽  
Geng Cao ◽  
ShengHui Yu ◽  
XinHao Ren ◽  
...  

2021 ◽  
Vol 9 (2) ◽  
pp. 488
Author(s):  
Jefferson Ferreira da Silva ◽  
Stephany Diolino Cunha ◽  
Henyo Alves Rodrigues Dias ◽  
Matheus Da Silva Araújo ◽  
Ednaldo Cândido Rocha ◽  
...  

The objectives of this study were: to evaluate the leaching potential of B in a Latossolo Vermelho-Amarelo (Oxisol) as a function of sources and doses of this micronutrient; among the sources tested (boric acid, ulexite and the commercial source H2 Boro), to determine the one with the lowest leaching potential; to evaluate leaching losses at different doses in each soil layer evaluated; and to identify chemical and physical variables of soils that influence B leaching. For that, two experiments were conducted in a greenhouse. The first one tested B leaching in the soil, with the three sources under study and five doses of B (0; 12; 24; 36; and 48 kg ha-1), whereas the second experiment evaluated the influence of soil physical and chemical attributes on B leaching using soils randomly collected in 22 localities in southeastern Goiás, Brazil. Regardless of the dose applied, ulexite led to the lowest soluble B content in the profile of the analyzed soils and also in the leachate. Boric acid was the only source that showed a different behavior in relation to B content in the different soil layers and in the leachate. In the soil layer from 21 to 30 cm, ulexite is the source with the lowest soluble B content. The behaviors of the more soluble sources, in this case boric acid and H2 Boro (H2 Agrosciences - Monoethanolamine borate), regardless of the dose, are very similar, being highly leachable in the profile of the Oxisol used. Soils with clayey texture and higher values of H+Al and CEC were able to retain higher B contents in the upper portion their profiles (layers from 0 to 10 cm and 11 to 20 cm), but soils with sandy texture and higher values of sum of bases showed greater B losses by leaching.


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