scholarly journals Phosphorus Inactivation in Lake Sediments Using Calcite Materials and Controlled Resuspension—Mechanism and Efficiency

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 223
Author(s):  
Agnieszka Bańkowska-Sobczak ◽  
Aurelia Blazejczyk ◽  
Elisabeth Eiche ◽  
Uwe Fischer ◽  
Zbigniew Popek
Keyword(s):  
Adsorption Capacity ◽  
Soluble Reactive Phosphorus ◽  
High Dose ◽  
Eutrophic Lakes ◽  
Precipitated Calcium Carbonate ◽  
Anoxic Conditions ◽  
P Fraction ◽  
Reactive Phosphorus ◽  
High Doses

The efficiency and mechanism of orthophosphate—soluble reactive phosphorus (SRP)—inactivation in eutrophic lakes using controlled resuspension and calcite application into the sediment were investigated in this study. Two calcite materials, industrially produced precipitated calcium carbonate (PCC) and natural ground limestone (GCC), were tested in short-term batch experiments and long-term sediment incubations under oxic and anoxic conditions. Maximum SRP adsorption capacity calculated using Langmuir model for PCC (3.11 mg PO43− g−1) was 6 times higher than of GCC (0.43 mg PO43− g−1), reflecting substantial difference in the surface area of calcite materials (12.36 and 1.72 m2 g−1, respectively). PCC applied into the sediment during controlled resuspension reduced SRP release by 95% (oxic) and 78% (anoxic incubation) at medium dose (0.75 kg m−2) and suppressed it completely at high dose (1.5 kg m−2) for at least 3 months, irrespectively of incubation conditions. The maximum achieved reduction of SRP release using GCC was also meaningful: 78% under oxic and 56% under anoxic conditions, but this required very high doses of this material (6 kg m−2). Mechanisms of SRP inactivation by calcites were: (1) adsorption of SRP during application into the resuspended sediment and (2) precipitation of calcium-phosphate compounds (Ca-PO4) during subsequent incubation, which was reflected in a substantial increase in the HCl-P fraction (phosphorus extractable in 0.5 M HCl) in sediments enriched with calcite, irrespectively of oxygen presence. However, anoxia strongly promoted the formation of this fraction: the rise of HCl-P was 2–6 times higher in anoxic than in oxic conditions, depending on the dose and form of calcite applied. The results showed that SRP inactivation using the controlled resuspension method is only successful if highly efficient reactive materials are used, due to large amount of SRP being released from sediment during resuspension. Thus, calcite materials exhibiting high adsorption capacity should be used in this lakes’ restoration technology to ensure fast and sufficient SRP inactivation. The rise in the HCl-P fraction in sediment suggests SRP inactivation through precipitation of relatively stable Ca-PO4 minerals, which makes calcite a suitable agent for sustainable, long term SRP inactivation. As anoxic conditions promoted formation of these compounds, calcite seems to be a promising SRP inactivation agent in highly reductive sediments.

Effects of long-term continuous GnRH administration on the pituitary–gonadal axis in Eld's deer stags (Cervus eldi thamin)

1995 ◽  
Vol 73 (9) ◽  
pp. 1609-1619 ◽  
Author(s):  
S. L. Monfort ◽  
J. L. Brown ◽  
T. C. Wood ◽  
M. Bush ◽  
L. R. Williamson ◽  
...  
Keyword(s):  
Dose Group ◽  
Low Dose ◽  
High Dose ◽  
Fertile Period ◽  
Nonbreeding Season ◽  
Testosterone Secretion ◽  
High Doses ◽  
Seasonal Decline ◽  
Seasonally Breeding

Eld's deer stags (Cervus eldi thamin) (in groups of three) were continuously administered gonadotropin-releasing hormone (GnRH) in control, low, medium, or high doses (0, 20.1 ± 0.7, 83.3 ± 2.6, and 292.9 ± 4.9 ng∙kg−1∙d−1, respectively) via osmotic minipumps for ~80 d to investigate the potential for precociously reactivating the pituitary–testicular axis during the nonbreeding season. Secretory patterns of LH, FSH, and testosterone concentrations were qualitatively similar among treatments. However, in the low-dose group, basal LH and FSH concentrations were both increased (p < 0.05) and pituitary responsiveness to a superimposed GnRH challenge was augmented (p < 0.05) after 12 weeks of treatment compared with all other groups. Despite these endocrine changes, continuous low-dose GnRH administration was not effective for precociously inducing testicular activity in this seasonally breeding species. High-dose GnRH administration initially induced a transient increase in LH, FSH, and testosterone secretion and delayed, but did not prevent, the seasonal decline in spermatogenesis. After 6–12 weeks of high-dose GnRH administration, however, attenuated pituitary responsiveness appeared to delay the normal seasonal reactivation of the pituitary–gonadal axis. In conclusion, prolonged, continuous low-dose GnRH administration did not effectively translate into a precocious onset of testicular activity; therefore, this specific approach is unlikely to be useful for prolonging the fertile period in this seasonally breeding species.

Fluconazole-Induced Symptomatic Phenytoin Toxicity

1994 ◽  
Vol 28 (2) ◽  
pp. 191-195 ◽  
Author(s):  
Richard M. Cadle ◽  
Golden J. Zenon ◽  
Maria C. Rodriguez-Barradas ◽  
Richard J. Hamill
Keyword(s):  
Continuous Monitoring ◽  
Case Reports ◽  
Review Literature ◽  
High Dose ◽  
Data Synthesis ◽  
High Doses ◽  
Phenytoin Toxicity ◽  
Cytochrome P 450 ◽  
Hepatic Cytochrome

OBJECTIVE: To report two cases of fluconazole-induced symptomatic phenytoin toxicity and review literature related to this interaction. DATA SOURCES: Case reports and review articles identified by a computerized (MEDLINE) and manual ( Index Medicus) search. DATA SYNTHESIS: Fluconazole is a broad-spectrum triazole antifungal agent primarily eliminated by renal mechanisms, although hepatic cytochrome P-450 inhibition and hepatotoxicity have been observed. We report two cases of fluconazole-induced symptomatic phenytoin toxicity. Both patients received high doses of the drug; one patient developed phenytoin toxicity only after long-term coadministration. Previously reported cases have occurred primarily with high-dose fluconazole and short-term coadministration. CONCLUSIONS: Fluconazole can increase phenytoin serum concentrations leading to toxicity. Constant and continuous monitoring of serum phenytoin concentrations with fluconazole doses as low as 200 mg/d is warranted.

scholarly journals Limnological characterisation and phytoplankton seasonal variation in a subtropical shallow lake (Guaiba Lake, Brazil): a long-term study

2014 ◽  
Vol 26 (4) ◽  
pp. 442-456 ◽  
Author(s):  
Rodrigo da Rocha Andrade ◽  
Danilo Giroldo
Keyword(s):  
Shallow Lake ◽  
Soluble Reactive Phosphorus ◽  
Late Summer ◽  
Euphotic Zone ◽  
Subtropical Zone ◽  
Chl A ◽  
Relative Contribution ◽  
Long Term Study ◽  
Reactive Phosphorus

AIM: to provide a long-term limnological characterisation of a subtropical shallow lake in addition to verifying seasonal differences, including phytoplankton variation. METHODS: monthly sampling at sites IP, SJ and MD from 2000 to 2009 to analyse temperature - T; depth - Z; the depth of the euphotic zone - Zeu; Zeu/Z (%); total suspended solids - TSS; dissolved oxygen - DO; pH; electrical conductivity - EC; N-NH3, N-NO2, N-NO3; soluble reactive phosphorus - SRP; chlorophyll a - Chl-a and phytoplankton. RESULTS: low values of Z and Zeu characterised the shallow and turbid conditions of lake and corresponded to the contribution of nano-microflagellates (Chlamydomonas sp., Spermatozopsis sp., Cryptomonas sp. and Rhodomonas sp ) and diatoms (Aulacoseira granulata). Zeu/Z (%), SRP and Chl-a were significantly different at site IP (meso-eutrophic) compared to sites SJ and MD (eutrophic). Phytoplankton density was also significantly higher at sites SJ and MD, and the largest relative contribution of Actinastrum sp., Dictyosphaerium sp., Micractinium sp., Monoraphidium sp., Scenedesmus/Desmodesmus sp. and Euglena sp. corresponded to the most polluted waters at site SJ. The significantly higher T (ºC) in summer corresponded to significantly higher Chl-a as well as a greater richness and density of phytoplankton. Cocconeis sp., Gomphonema sp. and Pinnularia sp. (pennated diatoms) were negatively correlated with temperature and were therefore more representative at the three sites in winter. Asterionella formosa was correlated with SRP and vernal blooms were recorded (2000-2001). Planktothrix isothrix and Planktothricoides raciborskii were expressive in the summer/late summer (2004-2005), and were significantly correlated with Chl-a and low SRP in water column. CONCLUSIONS: The study corroborated the sensitivity of phytoplankton in characterising different stages of eutrophication at different sites and corresponding watersheds as well as in characterising different seasons in a shallow lake in the subtropical zone of Brazil.

scholarly journals Long-Term Study of Soluble Reactive Phosphorus Concentration in Fall Creek and Comparison to Northeastern Tributaries of Cayuga Lake, NY: Implications for Watershed Monitoring and Management

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2075 ◽  
Author(s):  
O’Leary ◽  
Johnston ◽  
Gardner ◽  
Penningroth ◽  
Bouldin
Keyword(s):  
Flow Rate ◽  
Algal Blooms ◽  
Soluble Reactive Phosphorus ◽  
Phosphorus Concentration ◽  
Term Study ◽  
Long Term Study ◽  
Cayuga Lake ◽  
Significant Difference ◽  
Reactive Phosphorus

This study focuses on soluble reactive phosphorus (SRP), a key driver of eutrophication worldwide and a potential contributor to the emerging global environmental problem of harmful algal blooms (HABs). Two studies of tributary SRP concentrations were undertaken in sub-watersheds of Cayuga Lake, NY, the subject of a total maximum daily load (TMDL) development process, due to phosphorus impairment of its southern shelf. The long-term study compared SRP concentration in Fall Creek in the 1970s with that in the first decade of the 2000s, thus spanning a period of change in phosphorus sources, as well as in regional climate. The spatial study used data collected between 2009 and 2018 and compared SRP concentrations in Fall Creek to levels in northeastern tributaries that flow into the lake close to areas where HABs have been problematic. SRP was measured using standard procedures. Flow-weighted mean SRP concentration ranged between 15.0 µg/L and 30.0 µg/L in all years studied in both the 1970s and 2000s, with the exception of 2010. Annual discharge in Fall Creek showed no trend between 1970 and 2018, but a higher proportion of high streamflow samples was captured in the 2000s compared to the 1970s, which resulted in proportionally increased SRP concentration in the latter time period. There was no significant difference in the SRP concentration—flow rate relationship between the two time periods. Adjusted for flow rate, SRP concentrations in Fall Creek have not changed over many decades. Increasing phosphorus contributions from growing population and urbanization since the 1970s may have been counterbalanced by improvements in wastewater treatment and agricultural practices. Mean SRP concentration in northeastern tributaries was significantly (p < 0.001) higher than in Fall Creek, likely reflecting more intense agricultural use and higher septic system density in the watersheds of the former. This finding justifies continued monitoring of minor northern tributaries. Future monitoring must emphasize the capture of high flow conditions. Historical stability and highly variable hydrology will slow the watershed response to management and confound the ability to detect changes attributable to decreased phosphorus inputs. Large scale monitoring on decadal timescales will be necessary to facilitate watershed management.

Hypolimnetic Aeration: An Overview

1986 ◽  
Vol 21 (2) ◽  
pp. 205-217 ◽  
Author(s):  
D.J. McQueen ◽  
D.R.S. Lean
Keyword(s):  
Ammonia Volatilization ◽  
Cold Water ◽  
Soluble Reactive Phosphorus ◽  
Eutrophic Lakes ◽  
Hypolimnetic Oxygen ◽  
Dissolved Hydrogen ◽  
Phosphorus Sedimentation ◽  
Reactive Phosphorus ◽  
Maximum Removal

Abstract Hypolimnetic aerators are now being widely used throughout Europe and are beginning to appear in small and medium sized eutrophic lakes in temperate North America. This activity has produced approximately 42 published reports dealing with experiments conducted at 16 lakes. Taken together, the evidence from these experiments suggests that well designed aerators do not cause significant destratification or warming of hypolimnetic water, but do result in measurable Increases in hypolimnetic oxygen concentration and decreases in dissolved hydrogen sulfide, methane and ammonia. Early experiments suggested that phosphorus sedimentation was unpredictable, but recent work has demonstrated that when the ratio of total iron to soluble reactive phosphorus exceeds 10:1 and pH is &lt; 7.5, phosphorus sedimentation is assured and internal loading greatly reduced. Early experiments also showed that ammonia volatilization was unpredictable, but at pH &gt; 8.0, ammonia volatilization will occur. Because both phosphorus sedimentation and nitrogen reduction are pH dependent, both cannot be optimally removed during the same period of time and so the experimenter is advised to select for the maximum removal of one or the other through pH manipulation. Hypolimnetic aeration induces oxygen consumption and this must be considered when choosing an appropriate compressor size. Most studies show little impact on phytoplankton blomass, but one recent experiment showed that aeration during spring turnover resulted in reduced concentrations of chlorophyll a and TP. Zooplankton populations are, for the most part, unaffected and a number of American studies have shown that hypolimnetically aerated lakes can support cold water fish populations. The aggregate practical and experimental experience suggests that well designed hypolimnetic aeration systems yield measurable improvements in water quality and will almost certainly prove to be one of the major methods used for future in situ lake restoration.

Long-term treatment with finasteride induces apoptosis and pathological changes in female mice

2019 ◽  
Vol 38 (7) ◽  
pp. 762-774 ◽  
Author(s):  
AA Alkahtane ◽  
G Albasher ◽  
NK Al-Sultan ◽  
WS Alqahtani ◽  
S Alarifi ◽  
...  
Keyword(s):  
Serum Levels ◽  
Term Treatment ◽  
Androgenetic Alopecia ◽  
High Dose ◽  
Histopathological Analysis ◽  
Once Daily ◽  
Female Mice ◽  
Long Term Treatment ◽  
High Doses

Androgenetic alopecia is the most common type of alopecia, and it affects humans of both genders. Finasteride is a type II selective 5α-reductase inhibitor that is administered orally to treat androgenetic alopecia and benign prostatic hyperplasia in human males. However, its effect on the vital organs of females is unknown. This study was designed to investigate the effects of finasteride on the vital organs such as liver, kidney, and heart of female mice. To study the prospective effects of finasteride, female mice were orally administered two doses of finasteride (0.5 and 1.5 mg/kg) once daily for 35 days, and serum levels of various biochemical parameters and histopathology of various organs were examined. The results showed that serum levels of alkaline phosphatase were significantly increased by both high- and low-dose finasteride, whereas cholesterol was significantly increased by the high dose only. Creatine kinase was significantly increased by the high and low doses, whereas glucose was significantly decreased by both doses. Histopathological analysis and DNA damage assays showed that finasteride has adverse effects within both the short and the long periods in female mice. In addition, the proapoptotic genes Bax and caspase-3 were significantly increased by high dose finasteride, whereas the antiapoptotic gene Bcl-2 was significantly decreased by the low and high doses. In conclusion, finasteride is not currently approved for therapeutic use in females, and the findings in this study suggest caution in any future consideration of such use.

scholarly journals The influences of historic lake trophy and mixing regime changes on long-term phosphorus fractions retention in sediments of deep, eutrophic lakes: a case study from Lake Burgäschi, Switzerland

2019 ◽  
Author(s):  
Luyao Tu ◽  
Paul Zander ◽  
Sönke Szidat ◽  
Ronald Lloren ◽  
Martin Grosjean
Keyword(s):  
Binding Capacity ◽  
Redox Conditions ◽  
P Availability ◽  
P Fractions ◽  
Eutrophic Lakes ◽  
Anoxic Hypolimnion ◽  
P Fraction ◽  
Labile P ◽  
Total P

Abstract. Hypolimnetic anoxia in eutrophic lakes can delay lake recovery to lower trophic states via the release of sediment phosphorus (P) to surface waters on short time scales. However, the effects of hypolimnetic redox conditions and eutrophication on long-term sediment P-fraction retention are not clear yet. In this study, we investigated the sediment profiles since the early 1900s from Lake Burgäschi, a deep, eutrophic lake on the Swiss Plateau. The changes of sediment P-fraction retention were assessed with respect to lake trophic evolution (sedimentary green-pigments proxy), hypolimnetic oxygenation regime (Fe / Mn ratio proxy), sediment geochemical characteristics, and lake restoration history. Results showed that long-term retention of total P and labile P-fractions in sediments was predominantly affected by autochthonous Fe and Mn preserved in anoxic sediments, which were controlled by past hypolimnetic redox conditions. By contrast, refractory HCl-P (Ca-P) fraction retention largely resulted from authigenic CaCO3-P precipitation and increased with higher eutrophic levels. The retention of total P and labile P fractions was considerably reduced in surface sediments from 1977–2017 when Lake Burgäschi had the highest eutrophic levels and a persistent anoxic hypolimnion. We attributed the phenomenon to reduced sediment P-binding capacity (Mn and Fe oxyhydroxides) under the eutrophication-induced anoxic hypolimnion and decreased water-P concentrations due to hypolimnetic withdrawal. Our study implies that in seasonally stratified deep lakes like Lake Burgäschi, hypolimnetic withdrawal of P-enriched water can effectively reduce P retention in sediments and potentials of sediment-P release (seen from low P availability after 1977). However, the restoration has not improved lake trophic state, similarly to the findings from lake limnological survey.

Immunomodulatory Effect of Ganoderma Lucidum Polysaccharides (GLP) on Long-Term Heavy-Load Exercising Mice

2012 ◽  
Vol 82 (6) ◽  
pp. 383-390 ◽  
Author(s):  
Yali Shi ◽  
Dehua Cai ◽  
Xiaojie Wang ◽  
Xinshen Liu
Keyword(s):  
Absolute Neutrophil Count ◽  
Neutrophil Count ◽  
Ganoderma Lucidum ◽  
Phagocytic Index ◽  
High Dose ◽  
Heavy Load ◽  
Ganoderma Lucidum Polysaccharides ◽  
High Doses ◽  
Serum Agglutination

Long-term heavy-load exercise can lead to a decrease in the organism’s immune response. In this study, we used 100 Kunming (KM) mice to investigate the immune-regulatory effects of Ganoderma lucidum polysaccharides (GLP) on long-term heavy-load exercising mice. Peripheral white blood cells (WBC), the absolute value of neutrophils (NEUT), the phagocytic function of macrophages, serum agglutination valence, and the number of plaque-forming cells (PFC) were evaluated 4 weeks after gavaging long-term heavy-load exercising mice with GLP. After exercise, the WBC count in peripheral blood, absolute neutrophil count, macrophage phagocytic index, serum agglutination valence, and the number of plaque-forming cells were significantly reduced in the mice not fed GLP. Both medium and high doses of GLP drastically increased peripheral WBC, absolute neutrophil count, macrophage phagocytic index, serum agglutination valence, and the number of plaque-forming cells in long-term heavy-load exercising mice. High doses of GLP increased peritoneal macrophage phagocytic rate considerably. With this study, we demonstrate that 4 weeks of heavy-load exercise can lead to exercise-induced immunosuppression in mice. A supplement of GLP fed to these mice improves both non-specific and specific immune responses among these mice. The effect for the high-dose GLP treatment is especially significant.

Cognitive impairment following clinical or recreational use of gamma-hydroxybutyric acid (GHB). A systematic review

2021 ◽  
Vol 19 ◽  
Author(s):  
Jan Van Amsterdam ◽  
Tibor M. Brunt ◽  
Filipa Raposo Pereira ◽  
Cleo L. Crunelle ◽  
Wim Van Den Brink
Keyword(s):  
Systematic Review ◽  
Cognitive Impairments ◽  
High Dose ◽  
General Anaesthetic ◽  
Hydroxybutyric Acid ◽  
Alcohol Relapse ◽  
Animal Data ◽  
High Doses ◽  
Recreational Use

Background: GHB (gamma-hydroxybutyric acid; sodium oxybate) is a general anaesthetic that is clinically used for the treatment of narcolepsy, cataplexy, alcohol withdrawal and alcohol relapse prevention. In addition, GHB is recreationally used. Most clinical and recreational users regard GHB as an innocent drug devoid of adverse effects, despite its high dependence potential and possible neurotoxic effects. At high doses, GHB may lead to a comatose state. This paper systematically reviews possible cognitive impairments due to clinical and recreational GHB use. Methods: PubMed and PsychINFO were searched for literature data about the acute and residual cognitive deficits following GHB use. This review is conducted using the PRISMA protocol. Results: A total of 43 reports covering human and animal data on GHB-induced cognitive impairments were eligible and reviewed. This systematic review found no indication for cognitive impairments after clinical GHB use. However, it supports the view that moderate GHB use may result in acute short-term cognitive impairments, whereas regular high-dose GHB use and/or multiple GHB-induced comas are probably neurotoxic resulting in long-term residual cognitive impairments. Conclusion: These results emphasize the need for awareness among clinicians and recreational users to minimize negative health consequences of recreational GHB use, particularly when high doses are used, and GHB-induced comas occur.

Major controls of base flow soluble reactive phosphorus losses in humid temperate headwater streams

2020 ◽  
Author(s):  
Michael Rode ◽  
Remi Dupas
Keyword(s):  
Land Use ◽  
Headwater Streams ◽  
Soluble Reactive Phosphorus ◽  
Low Flow ◽  
Temperate Climate ◽  
Redox Processes ◽  
Temperature Dependent ◽  
P Release ◽  
Reactive Phosphorus

&lt;p&gt;Long-term Soluble Reactive Phosphorus (SRP) monitoring in headwater streams in central Europe revealed a seasonal pattern of SRP concentrations during low flow periods, with highest concentrations in summer and lowest in winter. These seasonal concentration amplitudes often exceed the eutrophication threshold during the summer eutrophication-sensitive period. It is assumed that temperature dependent biogeochemical processes control the underlying P release mechanism, where redox processes may be responsible for this increase. Several studies have highlighted the crucial role of reactive zones such as riparian wetlands in controlling solute export regimes. Moreover especially in forest headwater streams, in-stream assimilatory uptake shows a distinct seasonal behaviour because of varying shading conditions. This can also lead to seasonal SRP amplitudes. Furthermore sorption and desorption processes are temperature dependent which may alter in-stream SRP release during the year.&lt;/p&gt;&lt;p&gt;Often SRP concentrations are higher in agricultural streams than in more pristine headwaters. It is not clear how land use (e.g. P status of soils) may impact the baseline SRP concentrations and which factors control the seasonal change in SRP stream concentration (riparian groundwater heads and redox processes, temperature, in-stream release and uptake processes). Therefore the objective of this study is to disentangle land use impacts from hydrological and biogeochemical controls of low flow SRP losses.&amp;#160; A comparative study on seasonal SRP concentration patterns will be presented comprising around 53 long term monitored headwater catchments in humid temperate climate of northern Europe and the United States. Based on hydrological and SRP headwater signals and catchment properties, P release processes are discussed. The results of the study will allow to target SRP mitigation strategies based on knowledge of the dominating control of SRP loss from headwater streams.&amp;#160;&lt;/p&gt;

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