scholarly journals Extractable aluminium, iron and manganese in mineral soils: I Dependence of extractability on the pH of oxalate, pyrophosphate and EDTA extractants

1989 ◽  
Vol 61 (2) ◽  
pp. 73-78 ◽  
Author(s):  
Raina Niskanen
Keyword(s):  
Supporting Electrolyte ◽  
Pka Values ◽  
Fe And Mn ◽  
Mineral Soils ◽  
Ph Range ◽  
Iron And Manganese

Al, Fe and Mn in two mineral soils were extracted by 0.05 M and 0.02 M oxalate and pyrophosphate and 0.02 M EDTA solutions the pH of which was adjusted to values ranging from 1.7 to 11.0. The extractability of metals tended to decrease as the pH rose and as the deprotonation of extractant acid, expressed as pKa values, progressed. The reduction in extractability of metals by oxalate was rather steep at pH > 4, whereas the extractability by pyrophosphate remained moderate at a wider pH range. The extractability of metals by EDTA (pH 3.6—7.3) was lower than that by oxalate and pyrophosphate. Extractability was lower in the absence of the studied oxyacid anions and with 0.01 M KCI as the supporting electrolyte at a pH between 2 and 11 than in their presence.

scholarly journals Extractable aluminium, iron and manganese in mineral soils: II Extractability by oxalate and pyrophosphate

1989 ◽  
Vol 61 (2) ◽  
pp. 79-87
Author(s):  
Raina Niskanen
Keyword(s):  
Mean Values ◽  
Analytical Work ◽  
Fe And Mn ◽  
The Mean ◽  
Mineral Soils ◽  
Iron And Manganese

The extractability of aluminium, iron and manganese by 0.05 M oxalate and pyrophosphate was studied in samples of 23 mineral soils. Dilute extractants were studied because conventional reagents may cause problems in analytical work. The mean values for Al, Fe and Mn extracted by conventional Tamm’s oxalate were 67, 81 and 1.5 mmol/kg soil, respectively. On the average, 0.05 M oxalate solutions at pH 2.9 and 4.2 extracted Al, Fe and Mn amounts that were 103, 113 and 87 % and 72, 82 and 83 % of the amounts extractable by Tamm’s oxalate, respectively. Eeach metal released by 0.05 M oxalates correlated closely with that dissolved by Tamm’s oxalate; the r values ranged from 0.967*** to 0.997***. The mean values for Al, Fe and Mn extracted by 0.1 M Na4P2O7 and 0.05 M K4P2O7 were 38, 28 and 0.6 and 33, 29 and 0.6 mmol/kg soil, respectively. The amount of each metal extracted by Na4P2O7 correlated closely with that released by K4P2O7; the r values ranged from 0.87*** to 0.97***.

scholarly journals Evidence that the active centre of chymopapain A is different from the active centres of some other cysteine proteinases and that the Brønsted coefficient (βnuc.) for the reactions of thiolate anions with 2,2′-dipyridyl disulphide may be decreased by reagent protonation

1980 ◽  
Vol 189 (1) ◽  
pp. 189-192 ◽  
Author(s):  
K Brocklehurst ◽  
B S Baines ◽  
M S Mushiri
Keyword(s):  
Carica Papaya ◽  
Cysteine Proteinases ◽  
Active Centre ◽  
Pka Values ◽  
Nitrobenzoic Acid ◽  
Specific Reactivity ◽  
Ph Range ◽  
Thiolate Anions ◽  
Active Centres

The active centres of chymopapains A and B (jointly designated EC 3.4.22.6) and papaya (Carica papaya L.) peptidase A were investigated by using 2,2′-dipyridyl disulphide and 5,5′-dithiobis-(2-nitrobenzoic acid) as thiol-specific reactivity probes. Whereas the first active-centre pKa values for chymopapain B and papaya peptidase A are less than 5, is as the case for papain (EC 3.4.22.2) and ficin (EC 3.4.22.3), that for chymopapain A is about 6.8. The reason why the reactions of thiols of pKa approx. 6.5 with 2.2′-dipyridyl disulphide are essentially pH-independent in the pH range around the thiol pKa is delineated. The value of the Brønsted coefficient (beta nuc.) for the reactions of thiolate ions with the 2,2′-dipyridyl disulphide monocation appears to be smaller than its value for the corresponding reactions with the neutral disulphide.

scholarly journals Evaluation of in vitro antagonistic activity of fungi from peatlands against Ganoderma species under acidic condition

2020 ◽  
Vol 21 (7) ◽  
Author(s):  
SUPRIYANTO ◽  
PURWANTO ◽  
S.H. POROMARTO ◽  
SUPYANI
Keyword(s):  
Biological Control ◽  
Antagonistic Activity ◽  
Biological Control Agents ◽  
Antagonistic Fungi ◽  
High Incidence ◽  
Acidic Conditions ◽  
Mineral Soils ◽  
Ph Range ◽  
Biological Methods

Abstract. Supriyanto, Purwanto, Poromarto SH, Supyani. 2020. Evaluation of in vitro antagonistic activity of fungi from peatlands against Ganoderma species under acidic conditions. Biodiversitas 21: 2935-2945. The use of peatlands is a significant contributor to the world’s palm oil production. A serious problem of oil palm plantations in peatlands is the high incidence of basal stem rot (BSR) disease caused by Ganoderma, which has a higher attack rate than on mineral soils. There is no effective way to control Ganoderma in peatlands. At present, the effort for the same focuses on environment-friendly biological methods; however, this is constrained by the unavailability of appropriate biological agents for peatlands. The development of biological control agents for peatlands is hampered by limited data on biological control of Ganoderma in peatlands. This research was conducted to evaluate the in vitro antagonistic activity of fungi isolated from a peatland in acidic pH conditions. Twenty-seven Ganoderma-antagonistic fungi from peatland were evaluated for their activity and their ability to antagonism in vitro within a pH range of 2-7. The results show that most antagonistic fungi from peatland, based on biomass weight, the sporulation ability, and germination of conidium, were able to grow optimally at pH 3.0-4.0, indicating that most of the Ganoderma-antagonistic fungi from peatland can be used as biological control agents for BSR on oil palms in peatlands.

scholarly journals On iron flagellates

1946 ◽  
Vol 232 (588) ◽  
pp. 311-342 ◽  
Keyword(s):  
Organic Substances ◽  
Habitat Conditions ◽  
Liquid Media ◽  
Brown Colour ◽  
Fe And Mn ◽  
Iron Deposits ◽  
Manganese Compounds ◽  
Small Content ◽  
Iron And Manganese

The physiology and morphology of iron- and manganese-depositing flagellates are investigated by means of cultural experiments, with special reference to Anthophysa vegetans Stein, Siderodendron manganiferum n.gen., n.sp., Siphomonas Fritschii n.gen., n.sp. and Bikosoeca ( Poteriodendron ) petiolata (Stein) n.comb. Anthophysa multiplies in various liquid media containing small amounts of organic substances, hay decoction being specially favourable. Still better results are achieved with soil-water cultures, which afford the only successful cultures of Siderodendron and Siphomonas , while Bikosoeca also grows well in hay infusions. Addition of Fe" and Mn" is essential. The brown colour of biological iron deposits is shown to be due to admixture of manganese compounds, while mere ferric precipitates are in microscopical amounts almost colourless. Anthophysa and Siderodendron deposit more manganese than iron, so that their stalks appear brown, while those of Siphomonas are generally light brown. The envelopes of Bikosoeca are almost entirely composed of ferric compounds and appear colourless or faintly yellowish. All four organisms exhibit various modifications according to the habitat conditions. The formation of stalks and envelopes respectively depends on the availability of the relevant metals in the form of lower oxides, but the organisms here described can also exist without producing these structures. The oxidation of ferrous and manganese compounds is catalysed by the cells of these flagellates, although the role of this process in the cellular metabolism is not known. Nutrition is holozoic, chiefly by ingestion of bacteria. Like other holozoic flagellates these organisms cannot exist in the presence of an abundant bacterial vegetation owing to the resulting lack of oxygen. They thrive in quiet, well-aerated waters, with a small content of organic substances, above zones in which Fe and Mn compounds are reduced and from which ferrous and manganous compounds diffuse to the overlying oxidation zone, where these flagellates deposit Fe"' and Mn'" in a morphologically defined form. ‘Iron’ flagellates generally live in association and competition with iron bacteria of the Leptothrix group, the removal of which produces much better growth. A description of the relevant flagellates and of their appearance under various conditions, as well as diagnoses of Siderodendron and Siphomonas , are given.

scholarly journals Coulometric-potentiometric determination of pKA of several organic bases in propylene carbonate

2008 ◽  
Vol 73 (6) ◽  
pp. 655-659
Author(s):  
Ljiljana Jaksic ◽  
Radmila Dzudovic
Keyword(s):  
Propylene Carbonate ◽  
Supporting Electrolyte ◽  
Sodium Perchlorate ◽  
Potentiometric Method ◽  
Potentiometric Determination ◽  
Pka Values ◽  
Reference Base ◽  
Organic Bases ◽  
Standard Base

The pKA values of protonated triethylamine, pyridine and 2,2'-dipyridyl in propylene carbonate (PC) were determined by applying the coulometric-potentiometric method and a hydrogen/palladium generator anode (H2/Pd). The investigated and reference base were titrated to 50 % with protons electro-generated from hydrogen-saturated palladium, in the presence of sodium perchlorate as the supporting electrolyte. The half-neutralization potentials E1/2(x) and E1/2(st.) of the investigated and standard base, respectively, were measured using a glass-SCE pair. The obtained pKA values were compared with those reported in the literature.

scholarly journals Extractable aluminium, iron and manganese in mineral soils: III Comparison of extraction methods

1989 ◽  
Vol 61 (2) ◽  
pp. 89-97
Author(s):  
Raina Niskanen
Keyword(s):  
Organic Carbon ◽  
Soil Ph ◽  
Mineral Soil ◽  
Extraction Methods ◽  
Soil Characteristics ◽  
Organic Carbon Content ◽  
Extractable Metals ◽  
Mineral Soils ◽  
Extractable Al ◽  
Iron And Manganese

The extractability of soil Al, Fe and Mn were studied in 102 mineral soil samples. The extractants were 0.05 M oxalate (pH 2.9), 0.05 M K4P2O7 (pH 10), 0.02 M EDTA (pH 5.3) and 1 M CH3COONH4 (pH 4.8). In the group of clay and silt soils (n = 51), the Al extracted by the four extractants correlated closely; the r values ranged from 0.91*** to 0.96***; in coarser soils (n = 51) the r values ranged from 0.42* to 0.82***. In clay and silt soils, the organic carbon content and soil pH together explained 50 % of the variation in oxalate-extractable Al, 70 % of the variation in pyrophosphate-extractable Al, 53 % of the variation in pyrophosphate-extractable Fe and 56 % of the variation in acetate-extractable Al. The clay and organic carbon contents together with soil pH explained 77 % of the variation in EDTA-extractable Al in clay and silt soils. In coarse soils, the extractable metals were not closely related to the soil characteristics.

scholarly journals Accumulation of Zn, Cu, Fe, Mn and Pb due to brick manufacturing in agricultutral soils and plants

2016 ◽  
Vol 25 (1) ◽  
pp. 75-81 ◽  
Author(s):  
Abdul Halim Farhad Sikder ◽  
Sayma Khanom ◽  
Md Faruque Hossain ◽  
Zakia Parveen
Keyword(s):  
Heavy Metals ◽  
Agricultural Soil ◽  
Poor Quality ◽  
Maximum Amount ◽  
Agricultural Crops ◽  
Brick Kilns ◽  
Fe And Mn ◽  
Iron And Manganese

Experiment was carried out to assess the concentration of Zn, Cu, Pb, Fe and Mn in agricultural soil and plant near selected brick kilns. Soils and plants samples were collected from four points such as 250, 500, 1000 and 1500 m away from brick kilns. Three metals were found at elevated levels in the soils near brick kilns such as, Pb (92.5 to 214 mg/kg), Zn (86 to 156 mg/kg) and Cu (24.7 to 46.9 mg/kg). It may be caused due to burning of poor quality coal and fire woods. The uptake of heavy metals in the nearest areas (250 m) of the brick kilns was significantly higher than the areas far from the brick production and their concentrations range from 7 to 543 mg/kg for Pb, 23 to 101 mg/kg for Zn, 10 to 41 mg/kg for Cu, 35 to 1309 mg/kg for Fe and 26 to 126 mg/kg for Mn. Results indicated that soils and plants accumulated maximum amount of micronutrients within 500 to 1000 m distance from brick kilns significantly decreased with distance. Iron and manganese were not polluting the soils near brick kilns but affecting the plants. Therefore, it can be suggested that no agricultural crops should be grown within 1000 m distance from a brick kiln.Dhaka Univ. J. Biol. Sci. 25(1): 75-81, 2016

scholarly journals Iron and Manganese Retention of Juvenile Zebrafish (Danio rerio) Exposed to Contaminated Dietary Zooplankton (Daphnia pulex)—a Model Experiment

2020 ◽  
Vol 199 (2) ◽  
pp. 732-743
Author(s):  
Petra Herman ◽  
Milán Fehér ◽  
Áron Molnár ◽  
Sándor Harangi ◽  
Zsófi Sajtos ◽  
...  
Keyword(s):  
Danio Rerio ◽  
Daphnia Pulex ◽  
Negative Influence ◽  
Fish Growth ◽  
Trophic Chain ◽  
Concentration Data ◽  
Significant Difference ◽  
Fe And Mn ◽  
The Relationship ◽  
Iron And Manganese

AbstractIn present study the effect of iron (Fe) and manganese (Mn) contamination was assessed by modeling a freshwater food web of water, zooplankton (Daphnia pulex), and zebrafish (Danio rerio) under laboratory conditions. Metals were added to the rearing media of D. pulex, and enriched zooplankton was fed to zebrafish in a feeding trial. The elemental analysis of rearing water, zooplankton, and fish revealed significant difference in the treatments compared to the control. In D. pulex the Mn level increased almost in parallel with the dose of supplementation, as well as the Fe level differed statistically. A negative influence of the supplementation on the fish growth was observed: specific growth rate (SGR%) and weight gain (WG) decreased in Fe and Mn containing treatments. The redundancy analysis (RDA) of concentration data showed strong correlation between the rearing water and D. pulex, as well as the prey organism of Fe- and Mn-enriched D. pulex and the predator organism of D. rerio. The bioconcentration factors (BCF) calculated for water to zooplankton further proved the relationship between the Fe and Mn dosage applied in the treatments and measured in D. pulex. Trophic transfer factor (TTF) results also indicate that significant retention of the metals occurred in D. rerio individuals, however, in a much lower extent than in the water to zooplankton stage. Our study suggests that Fe and Mn significantly accumulate in the lower part of the trophic chain and retention is effective through the digestive track of zebrafish, yet no biomagnification occurs.

pH-Dependent Tautomerism and pKa Values of Phloroglucinol (1,3,5-Trihydroxybenzene), Studied by 13C NMR and UV Spectroscopy

1993 ◽  
Vol 48 (4) ◽  
pp. 478-482 ◽  
Author(s):  
Degui Wang ◽  
Knut Hildenbrand ◽  
Johannes Leitich ◽  
Heinz-Peter Schuchmann ◽  
Clemens von Sonntag
Keyword(s):  
13C Nmr ◽  
Uv Spectroscopy ◽  
Equilibrium Concentration ◽  
Keto Form ◽  
Pka Values ◽  
The Third ◽  
Ph Dependent ◽  
Ph Range ◽  
C Nmr

13C NMR and UV spectroscopy of aqueous phloroglucinol over the pH range 2.6 to 15 confirms that the dianion exists predominantly as the keto form (3,5-dihydroxy-2,5-cyclohexadienone dianion 2c, δ(>CH2) = 46 ppm, δ(≥CH) = 101 ppm, δ(C3,C5) = 188 ppm, δ(C1) = 197 ppm). All other states of ionization, i.e. neutral la (δ(>CH) = 98 ppm, δ(5(C1,C3,C5) = 160.9 ppm), monoanion 1b (δ(>CH) = 98 ppm, δ(C1,C3,C5) = 164.4 ppm) and trianion 1d (δ(>CH) = 100 ppm, δ(C1,C3,C5) = 170 ppm) exist predominantly as the benzene forms. There is some evidence, consisting of a broadening of the signals from the 3,5-dihydroxy-2,5-cyclohexadienone dianion 2c in the pH range from ∾ 9 where they start to appear, to ∾10 where they approach their maximum values, for a small but noticeable equilibrium concentration of the cyclohexen-1-ol-3,5-dione (monoanion) 3b or the 3,5-dihydroxy-2,5-cyclohexadienone (monoanion) 2b forms. Other keto forms have not been detected. The third pKa turns out to be close to 14.

Modulating the pKa Values of Hill-Type pH Probes for Biorelevant Acidic pH Range

2020 ◽  
Author(s):  
Yansheng Xiao ◽  
Fang Hu ◽  
Xiao Luo ◽  
Mingming Zhao ◽  
Zhenglong Sun ◽  
...  
Keyword(s):  
Acidic Ph ◽  
Pka Values ◽  
Ph Range ◽  
Ph Probes
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