Phaeocystis blooming enhanced by copepod predation on protozoa: evidence from incubation experiments

ABSTRACT The ovaries of ten patients, at least one year after the post-menopause, were incubated with two Δ5-C19-steroids and also studied histochemically. All these patients had post-menopausal uterine bleeding and increased oestrogen excretion of the urine. The urinary estimations of gonadotrophins, 17-KS, 17-OHCS and pregnanediol were carried out on all patients. Vaginal smears were read according to Papanicolaou, and the endometrium and ovaries were studied histologically. The incubation experiments indicate the presence of Δ5-3β-hydroxysteroid-dehydrogenase. When androst-5-ene-3β,17β-diol was used as precursor the formation of testosterone occurred without any concomitant production of DHA and/or androstenedione. This seems to indicate the possible role of the Δ5-pathway in the formation of testosterone by post-menopausal ovarian tissue. The histochemical reactions indicated a reducing activity on NADH, lactate and glucose-6-phosphate, in certain corpora albicantia, atretic follicles and in diffuse thecoma regions in the cortical layer of the ovary. Steroid-3β-ol-dehydrogenase and β-hydroxybutyrate-dehydrogenase were found only at the edges of certain corpora albicantia, in some individual stroma cell groups and in some atretic follicles. Our studies, both biochemical and histochemical, suggest that the observed increase in the urinary oestrogens of the patients studied might in part at least, be of ovarian origin. This opinion is also supported by the postoperative oestrogen values.

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Oceanic phytoplankton are a potentially important source of benzenoids to the remote marine atmosphere

Communications Earth & Environment ◽

10.1038/s43247-021-00253-0 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Manon Rocco ◽

Erin Dunne ◽

Maija Peltola ◽

Neill Barr ◽

Jonathan Williams ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Dimethyl Sulfide ◽

Laboratory Culture ◽

Marine Phytoplankton ◽

Marine Atmosphere ◽

Aerosol Formation ◽

Incubation Experiments ◽

Phytoplankton Communities ◽

Anthropogenic Air Pollutants ◽

Benzene Toluene

AbstractBenzene, toluene, ethylbenzene and xylenes can contribute to hydroxyl reactivity and secondary aerosol formation in the atmosphere. These aromatic hydrocarbons are typically classified as anthropogenic air pollutants, but there is growing evidence of biogenic sources, such as emissions from plants and phytoplankton. Here we use a series of shipborne measurements of the remote marine atmosphere, seawater mesocosm incubation experiments and phytoplankton laboratory cultures to investigate potential marine biogenic sources of these compounds in the oceanic atmosphere. Laboratory culture experiments confirmed marine phytoplankton are a source of benzene, toluene, ethylbenzene, xylenes and in mesocosm experiments their sea-air fluxes varied between seawater samples containing differing phytoplankton communities. These fluxes were of a similar magnitude or greater than the fluxes of dimethyl sulfide, which is considered to be the key reactive organic species in the marine atmosphere. Benzene, toluene, ethylbenzene, xylenes fluxes were observed to increase under elevated headspace ozone concentration in the mesocosm incubation experiments, indicating that phytoplankton produce these compounds in response to oxidative stress. Our findings suggest that biogenic sources of these gases may be sufficiently strong to influence atmospheric chemistry in some remote ocean regions.

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Alkalinity–silicon ratio as an assessment factor for the efficiency of silicate slags in wetland rice

Scientific Reports ◽

10.1038/s41598-021-84922-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Thoppil Sreenivasan Sandhya ◽

Nagabovanalli Basavarajappa Prakash

Keyword(s):

Silicon Content ◽

Chemical Properties ◽

Magnesium Content ◽

Wetland Rice ◽

Agronomic Efficiency ◽

Economic Production ◽

Incubation Experiments ◽

Calcium And Magnesium ◽

Si Content ◽

Assessment Factor

AbstractSilicate slags are one of the most widely used silicon (Si) source in agriculture. Even though the agronomic significance of slags has been demonstrated in several crops, only a few attempts were made to evaluate these Si sources based on their chemical composition. The main objective of this study was to characterize different silicate slags based on their chemical properties and to explore the effect of these chemical properties on the yield, and Si uptake in wetland rice, and dissolution of Si into the soil. Slags were characterised for pH, calcium and magnesium content (alkalinity, A), silicon content, 5 day Na2CO3 + NH4NO3 extractable Si content, and alkalinity to Si ratio (A/Si). Greenhouse and incubation experiments were also conducted using different silicate slags and wollastonite applied at the rate of 300 kg Si ha−1. Slags with A/Si < 3 were found to be ideal Si sources for the economic production of wetland rice and found consistent in increasing soil Si content and rice Si uptake. We conclude that the A/Si ratio of slags can be used as an important parameter to assess the agronomic efficiency of silicate slags in wetland rice.

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Emission of N2O from farmer's field during black gram cultivation and incubation experiments in laboratory

Toxicological and Environmental Chemistry ◽

10.1080/02772240903252157 ◽

2010 ◽

Vol 92 (6) ◽

pp. 1043-1052 ◽

Cited By ~ 3

Author(s):

S.K. Sahoo ◽

T.S. Ramulu ◽

Manish Kumar ◽

G. Roy Chaudhury ◽

S.N. Das

Keyword(s):

Black Gram ◽

Incubation Experiments

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Modification of atrzine desorption during field incubation experiments

The Science of The Total Environment ◽

10.1016/0048-9697(92)90158-o ◽

1992 ◽

Vol 123-124 ◽

pp. 333-344 ◽

Cited By ~ 25

Author(s):

Enrique Barriuso ◽

William Koskinen ◽

Brent Sorenson

Keyword(s):

Incubation Experiments ◽

Field Incubation

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EFFECTIVENESS OF ZINC FERTILIZER SOURCES ON NUTRITION OF BEANS

Canadian Journal of Soil Science ◽

10.4141/cjss86-019 ◽

1986 ◽

Vol 66 (1) ◽

pp. 183-187 ◽

Cited By ~ 9

Author(s):

J. P. SINGH ◽

J. W. B. STEWART ◽

R. E. KARAMANOS ◽

N. G. LEWIS

Keyword(s):

Key Words ◽

Biomass Production ◽

Relative Effectiveness ◽

High Yield ◽

Zn Deficiency ◽

Spent Sulphite Liquor ◽

Incubation Experiments ◽

Bean Plants ◽

Zn Content ◽

Zinc Fertilizer

The relative effectiveness of Zn-sulphate (ZnS), Zn-EDTA (ZnE), low-yield ammonium-based lignosulphonate (ZnLY) and high-yield sodium-based lignosulphonate (ZnHY) for bean production was tested in growth chamber and incubation experiments. ZnS and ZnLY were more effective than ZnE and ZnHY in correcting Zn deficiency of bean plants. While biomass production was best with ZnS, ZnLY was more effective in increasing Zn-content in the foliage and in the formation of strong chelates in the soil. Key words: Zn-sulfate, Zn-EDTA, lignosulphonate, spent sulphite liquor, sulphite pulping

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Oxygen isotope fractionation during N<sub>2</sub>O production by soil denitrification

Biogeosciences ◽

10.5194/bg-13-1129-2016 ◽

2016 ◽

Vol 13 (4) ◽

pp. 1129-1144 ◽

Cited By ~ 26

Author(s):

Dominika Lewicka-Szczebak ◽

Jens Dyckmans ◽

Jan Kaiser ◽

Alina Marca ◽

Jürgen Augustin ◽

...

Keyword(s):

Oxygen Isotope ◽

Soil Water ◽

Isotope Effect ◽

Isotope Exchange ◽

Isotope Fractionation ◽

Isotope Effects ◽

N2o Production ◽

Oxygen Isotope Fractionation ◽

Oxygen Isotope Exchange ◽

Incubation Experiments

Abstract. The isotopic composition of soil-derived N2O can help differentiate between N2O production pathways and estimate the fraction of N2O reduced to N2. Until now, δ18O of N2O has been rarely used in the interpretation of N2O isotopic signatures because of the rather complex oxygen isotope fractionations during N2O production by denitrification. The latter process involves nitrate reduction mediated through the following three enzymes: nitrate reductase (NAR), nitrite reductase (NIR) and nitric oxide reductase (NOR). Each step removes one oxygen atom as water (H2O), which gives rise to a branching isotope effect. Moreover, denitrification intermediates may partially or fully exchange oxygen isotopes with ambient water, which is associated with an exchange isotope effect. The main objective of this study was to decipher the mechanism of oxygen isotope fractionation during N2O production by soil denitrification and, in particular, to investigate the relationship between the extent of oxygen isotope exchange with soil water and the δ18O values of the produced N2O. In our soil incubation experiments Δ17O isotope tracing was applied for the first time to simultaneously determine the extent of oxygen isotope exchange and any associated oxygen isotope effect. We found that N2O formation in static anoxic incubation experiments was typically associated with oxygen isotope exchange close to 100 % and a stable difference between the 18O ∕ 16O ratio of soil water and the N2O product of δ18O(N2O ∕ H2O)  =  (17.5 ± 1.2) ‰. However, flow-through experiments gave lower oxygen isotope exchange down to 56 % and a higher δ18O(N2O ∕ H2O) of up to 37 ‰. The extent of isotope exchange and δ18O(N2O ∕ H2O) showed a significant correlation (R2 = 0.70, p < 0.00001). We hypothesize that this observation was due to the contribution of N2O from another production process, most probably fungal denitrification. An oxygen isotope fractionation model was used to test various scenarios with different magnitudes of branching isotope effects at different steps in the reduction process. The results suggest that during denitrification, isotope exchange occurs prior to isotope branching and that this exchange is mostly associated with the enzymatic nitrite reduction mediated by NIR. For bacterial denitrification, the branching isotope effect can be surprisingly low, about (0.0 ± 0.9) ‰, in contrast to fungal denitrification where higher values of up to 30 ‰ have been reported previously. This suggests that δ18O might be used as a tracer for differentiation between bacterial and fungal denitrification, due to their different magnitudes of branching isotope effects.

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Continuous measurements of nitrous oxide isotopomers during incubation experiments

10.5194/bg-2016-258 ◽

2016 ◽

Cited By ~ 1

Author(s):

Malte Winther ◽

David Balslev-Harder ◽

Søren Christensen ◽

Anders Priemé ◽

Bo Elberling ◽

...

Keyword(s):

Nitrous Oxide ◽

Greenhouse Gas ◽

Isotope Effect ◽

Atmospheric Chemistry ◽

Isotope Effects ◽

Denitrifying Bacteria ◽

Central Position ◽

Site Preference ◽

Continuous Measurements ◽

Incubation Experiments

Abstract. Nitrous oxide (N2O) is an important and strong greenhouse gas in the atmosphere and part of a feed-back loop with climate. N2O is produced by microbes during nitrification and denitrification in terrestrial and aquatic ecosystems. The main sinks for N2O are turnover by denitrification and photolysis and photo-oxidation in the stratosphere. The position of the isotope 15N in the linear N = N = O molecule can be distinguished between the central or terminal position (isotopomers of N2O). It has been demonstrated that nitrifying and denitrifying microbes have a different relative preference for the terminal and central position. Therefore, measurements of the site preference in N2O can be used to determine the source of N2O i.e. nitrification or denitrification. Recent instrument development allows for continuous (on the order of days) position dependent δ15N measurements at N2O concentrations relevant for studies of atmospheric chemistry. We present results from continuous incubation experiments with denitrifying bacteria, Pseudomonas fluorescens (producing and reducing N2O) and P. chlororaphis (only producing N2O). The continuous position dependent measurements reveal the transient pattern (KNO3 to N2O and N2, respectively), which can be compared to previous reported site preference (SP) values. We find bulk isotope effects of −5.5 ‰ ± 0.9 for P. chlororaphis. For P. fluorescens, the bulk isotope effect during production of N2O is −50.4 ‰ ± 9.3 and 8.5 ‰ ± 3.7 during N2O reduction. The values for P. fluorescens are in line with earlier findings, whereas the values for P. chlororaphis are larger than previously published δ15Nbulk measurements from production. The calculations of the SP isotope effect from the measurements of P. chlororaphis result in values of −6.6 ‰ ± 1.8. For P. fluorescens, the calculations results in SP values of −5.7 ‰ ± 5.6 during production of N2O and 2.3 ‰ ± 3.2 during reduction of N2O. In summary, we implemented continuous measurements of N2O isotopomers during incubation of denitrifying bacteria and believe that similar experiments will lead to a better understanding of denitrifying bacteria and N2O turnover in soils and sediments and ultimately hands-on knowledge on the biotic mechanisms behind greenhouse gas exchange of the Globe.

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IMMOBILIZATION OF EXCHANGEABLE CROMIUM IN A CONTAMINATED SOIL USING NATURAL ZEOLITE AS AN EFFECTIVE ADSORBENT

Vietnam Journal of Science and Technology ◽

10.15625/2525-2518/58/5a/15155 ◽

2020 ◽

Vol 58 (5A) ◽

pp. 10

Author(s):

Van Minh Dang ◽

Huu Tap Van ◽

Thi Bich Hanh Nguyen ◽

Dinh Vinh Nguyen ◽

Thị Tuyet Nguyen ◽

...

Keyword(s):

Soil Ph ◽

Contaminated Soil ◽

Contaminated Soils ◽

Natural Zeolite ◽

Organic Matters ◽

Amended Soils ◽

Mn Oxide ◽

Content Ratio ◽

Incubation Experiments ◽

Exchangeable Fraction

This work investigated the effects of soil pH and the content ratio of natural zeolite on Cr contaminated soil. The immobilization experiments of the exchangeable Cr in contaminated soils were conducted using the batch method. The incubation experiments were carried out over 30 days in plastic bottles to determine five fraction of Cr existence (exchangeable fraction (F1), Fe/Mn/Oxide (F2), carbonate bound (F3), organic matters (F4) and residual (F5)) in amended soils after incubation. Results showed that the content and proportion of the exchangeable Cr decreased with an increase in soil pH from 5 to 9. At soil pH 5, the exchangeable Cr in soil reduced from 44.80±0.772 mg/kg (initial soil) to 17.72±0.300 mg/kg after 30 days of incubation with natural Zeolite 3%. Meanwhile, the exchangeable Cr of soil also decreased with increasing the content ratio of natural zeolite from 1% to 5% in soil. The ratio of 3% was suitable for incubation of the exchangeable Cr in contaminated soil with natural zeolite. The exchangeable Cr in contaminated soil decreased from 80.34% at un-amended soil treatment to 25.06% after incubation of 30 days. The forms of carbonate bound (F3) and organic matters (F4) in amended soils increased to 36.54% and 28% compared with 4.26% and 6.90% in un-amended contaminated soil. Ion exchange, precipitation and adsorption on the surface of natural zeolite might be the potential mechanisms of immobilization of the exchangeable Cr. The results indicated that natural zeolite can be used as the effective adsorbent for immobilizing the exchangeable Cr in contaminated soils and leading to a decrease in the environmental risk from Cr toxicity.

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