Ecology of periphyton in a meltwater stream ecosystem in the maritime Antarctic

The ecology of two meltwater streams on King George Island, Ornithologists Creek (with penguin rookeries close to its lower reaches) and Petrified Forest Creek (a highly oligotrophic system), was studied during the 1996–97 summer season. To estimate seasonal productivity of the periphyton and to establish which environmental parameters influenced periphyton growth most strongly, two types of artificial substrata (fibreglass nets – ash-free dry weight (AFDW), and microscope slides – Chlorophyll a (Chl a)) were tested in situ. Thus relative periphyton productivity (RPP) reflects algal colonization and growth as well as losses due to cell mortality and abrasive action of moving sediments. The Petrified Forest Creek was more productive (AFDW = 108.63 μg cm−2 d−1, Chl a = 0.35 μg g cm−2 d−1) than the Ornithologists Creek (AFDW = 69.90 μg cm−2 d−-1, Chl a = 0.26 μg cm−2 d−1). RPP differed both along the streams, and during the season. Significant positive or negative relationships (generalized linear models) were found between RPP and streamwater ‘physico-chemical parameters’ and ‘geomorphological-geographical characteristics’ of the streams' catchments. In addition, in the lower reaches of both streams almost no active colonization or growth was recorded. In the Petrified Forest Creek, the periphyton biomass was so high that mainly passive organic matter deposition occurred. By contrast, in the lower reach of Ornithologists Creek, periphyton colonization and growth was around zero, being negatively influenced by penguin excrement. Ornithologists Creek was richer in nutrients (DIN, DRP), which also fluctuated more widely along its length and throughout the season, than in the Petrified Forest Creek. Parameters associated with the inorganic carbon cycle of the streamwater reflect higher RPP in Petrified Forest Creek. Moreover, RPP was higher in stream reaches with higher amounts of gravel boulders on the bottom.

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In situ dual crosslinking strategy to improve the physico-chemical properties of thermoplastic starch

Carbohydrate Polymers ◽

10.1016/j.carbpol.2021.118250 ◽

2021 ◽

pp. 118250

Author(s):

Hamed Peidayesh ◽

Abolfazl Heydari ◽

Katarína Mosnáčková ◽

Ivan Chodák

Keyword(s):

Chemical Properties ◽

Thermoplastic Starch ◽

Physico Chemical

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Positively Charged Lipid as Potential Tool to Influence the Fate of Ethosomes

Applied Sciences ◽

10.3390/app11157060 ◽

2021 ◽

Vol 11 (15) ◽

pp. 7060

Author(s):

Antonia Mancuso ◽

Maria Chiara Cristiano ◽

Massimo Fresta ◽

Daniele Torella ◽

Donatella Paolino

Keyword(s):

Cell Model ◽

Human Keratinocytes ◽

Skin Delivery ◽

Physico Chemical ◽

Cell Mortality ◽

Mean Size ◽

A Cell ◽

Negative Surface ◽

Cytotoxic Studies

Ethosomes® are one of the main deformable vesicles proposed to overcome the stratum corneum. They are composed of lecithin, ethanol and water, resulting in round vesicles characterized by a narrow size distribution and a negative surface charge. Taking into account their efficiency to deliver drugs into deeper skin layers, the current study was designed to evaluate the influence of different lipids on the physico-chemical features of traditional ethosomes in the attempt to influence their fate. Three lipids (DOPE, DSPE and DOTAP) were used for the study, but only DOTAP conferred a net positive charge to ethosomes, maintaining a narrow mean size lower than 300 nm and a good polydispersity index. Stability and in vitro cytotoxic studies have been performed using Turbiscan Lab analysis and MTT dye exclusion assay, respectively. Data recorded demonstrated the good stability of modified ethosomes and a reasonable absence of cell mortality when applied to human keratinocytes, NCTC 2544, which are used as a cell model. Finally, the best formulations were selected to evaluate their ability to encapsulate drugs, through the use of model compounds. Cationic ethosomes encapsulated oil red o and rhodamine b in amounts comparable to those recorded from conventional ethosomes (over 50%). Results recorded from this study are encouraging as cationic ethosomes may open new opportunities for skin delivery.

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Removal of heavy metal from soil and groundwater by in-situ electrokinetic remediation

Water Science & Technology ◽

10.2166/wst.2000.0586 ◽

2000 ◽

Vol 42 (7-8) ◽

pp. 335-343 ◽

Cited By ~ 4

Author(s):

S. Shiba ◽

S. Hino ◽

Y. Hirata ◽

T. Seno

Keyword(s):

Heavy Metals ◽

Heavy Metal ◽

Electric Potential ◽

Potential Gradient ◽

Electrokinetic Remediation ◽

Contaminated Aquifer ◽

Physico Chemical ◽

Operational Variables ◽

Mass Transport Process

The operational variables of electrokinetic remediation have not been cleared yet, because this method is relatively new and is an innovative technique in the aquifer remediation. In order to investigate the operational variables of the electrokinetic remediation, a mathematical model has been constructed based on the physico chemical mass transport process of heavy metals in pore water of contaminated aquifer. The transport of the heavy metals is driven not only by the hydraulic flow due to the injection of the purge water but also by the electromigration due to the application of the electric potential gradient. The electric potential between anode and cathode is the important operational variable for the electrokinetic remediation. From the numerical simulations with use of this model it is confirmed that the remediation starts from the up stream anode and gradually the heavy metal is transported to the down stream cathode and drawn out through the purge water.

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Some indicators of water quality of the Tamis river

Chemical Industry and Chemical Engineering Quarterly ◽

10.2298/ciceq100712060b ◽

2011 ◽

Vol 17 (1) ◽

pp. 107-115 ◽

Cited By ~ 3

Author(s):

Nada Babovic ◽

Dejan Markovic ◽

Vojkan Dimitrijevic ◽

Dragan Markovic

Keyword(s):

Water Quality ◽

Ph Value ◽

Ammonium Nitrogen ◽

Field Analysis ◽

Total Hardness ◽

Chemical Parameters ◽

Physico Chemical

This paper shows the results obtained in field analysis performed at the Tamis River, starting from the settlement Jasa Tomic - border between Serbia and Romania to Pancevo - confluence of Tamis into the Danube. The Tamis is a 359 km long river rising in the southern Carpathian Mountains. It flows through the Banat region and flows into the Danube near Pancevo. During the years the water quality of the river has severely deteriorated and badly affected the environment and the river ecosystem. In situ measurements enabled determination of physico-chemical parameters of water quality of the Tamis River on every 400 m of the watercourse, such as: water temperature, pH value, electrical conductivity, contents of dissolved oxygen and oxygen saturation. The main reason of higher pollution of Tamis is seen in connection to DTD hydro system. Sampling was performed at 7 points with regard to color, turbidity, total hardness, alkalinity, concentration of ammonium nitrogen, nitrite nitrogen, nitrate nitrogen, iron, chlorides and sulphates in samples. The aim of the present work was to evaluate water quality in the Tamis River taking into account significant pollution, which originates from settlements, industry and agriculture, and to suggest appropriate preventive measures to further pollution decreasing of the river's water.

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A Road Section near Guy's Hill, Jamaica

Geological Magazine ◽

10.1017/s0016756800073933 ◽

1942 ◽

Vol 79 (4) ◽

pp. 241-252 ◽

Cited By ~ 3

Author(s):

C. A. Matley ◽

Frank Raw

Keyword(s):

Sedimentary Rocks ◽

Plutonic Rock ◽

Igneous Rocks ◽

The Road ◽

Road Section ◽

Igneous Intrusions ◽

Microscope Slides

The rocks exposed along the road between Linstead and Guy's Hill, Jamaica, were described by Dr. C. T. Trechmann in this magazine in 1936 (pp. 259–260). The chief object of his account was to prove that the igneous rocks there were intrusions later than the associated Cretaceous and Tertiary limestones, which, according to him, had been metamorphosed into hornfelses, some of which, he stated later (1937, p. 561), he knew to have an “igneous” appearance under the microscope, “which tends to support my contention that in Jamaica we have sedimentaries altered in situ into rocks that would ordinarily be classified as igneous.” Dissent from his descriptions and interpretations was expressed by C. A. M. (Matley, 1937, pp. 501–3), the criticisms being mainly based on an examination of Trechmann's own microscope slides by F. R. A visit to Jamaica by C. A. M. in 1939 allowed him to study this road and to collect a suite of rocks for petrological examination. The results show that Trechmann's interpretation cannot be sustained. There is no granodiorite or other plutonic rock present, no metamorphism hornfelsing the sedimentary rocks, and no igneous intrusions into the Tertiary limestones.

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Assessing Soil and Plant Pollution by Abandoned Rural Waste Dumping Sites in Ningbo, China

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.138-139.1149 ◽

2011 ◽

Vol 138-139 ◽

pp. 1149-1155 ◽

Cited By ~ 1

Author(s):

Yi Dong Guan ◽

Ye Hong Du ◽

Zhen Dong Li ◽

An Cheng Luo

Keyword(s):

Heavy Metals ◽

Heavy Metal ◽

Reference Value ◽

Dry Weight ◽

Rice Grain ◽

Contamination Assessment ◽

Plant Parts ◽

Metal Contents ◽

Plant Pollution

This paper reports the concentration of heavy metals (Cr, Cu, Zn, Cd and Pb) in the soils and rices surrounding the abandoned rural waste dumping sites in Ningbo. Igeo (geoaccumulation index) was calculated to assess the contamination degree of heavy metals in soils. The mean contents of Cr, Cu, Cd, Zn and Pb of soils were 33.3, 24.1, 1.5, 118.9 and 45.6 mg/(kg DW) (dry weight), respectively. All of them were much higher than that of the reference value (i.e. CK), but there were no coherent trend of the metal contents within 1-120m distance from the dumping site. Igeo of heavy metals reveals the order of Cd>Cu>Cr>Pb>Zn, and the contamination assessment of soils using Igeo indicate the moderate Cd pollution, while the soils were unpolluted-moderately overall by Cr, Cu, Zn as well as Pb. The heavy metal contents in root, stem & leaf and rice grains were all remarkable higher than that of the CK at 20-120 m distances, and the heavy metal contents in root were evidently much higher than other plant parts, while those in rice grain were lowest, indicating the great bioaccumulation trend of heavy metals. Although the metal contents in the rice grain were within the legislation limit, its bioaccumulation trend of heavy metals was remarkable, whose contents were 4.38-fold for Cr, 1.76-fold for Cu, 1.28-fold for Zn, 2.67-fold for Cd and 3.03-fold for Pb higher than that of reference value, respectively. Finally, we proposed a decentralized in-situ restoration approach for the dumping sites.

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Soil physico-chemical characterization in the different soil layers of National Maize Research Program, Rampur, Chitwan, Nepal

Journal of Maize Research and Development ◽

10.3126/jmrd.v3i1.18918 ◽

2018 ◽

Vol 3 (1) ◽

pp. 28-44

Author(s):

Dinesh Khadka ◽

Sushil Lamichhane ◽

Amit P Timilsina ◽

Bandhu R Baral ◽

Kamal Sah ◽

...

Keyword(s):

Research Program ◽

Soil Structure ◽

Sandy Loam ◽

Chemical Properties ◽

Single Layer ◽

Chemical Characterization ◽

Bottom Layer ◽

Soil Parameters ◽

Physico Chemical

Soil pit digging and their precise study is a decision making tool to assess history and future of soil management of a particular area. Thus, the present study was carried out to differentiate soil physico-chemical properties in the different layers of excavated pit of the National Maize Research Program, Rampur, Chitwan, Nepal. Eight pits were dug randomly from three blocks at a depth of 0 to 100 cm. The soil parameters were determined in-situ, and in laboratory for texture, pH, OM, N, P (as P2O5), K (as K2O), Ca, Mg, S, B, Fe, Zn, Cu and Mn of collected soils samples of different layers following standard analytical methods at Soil Science Division, Khumaltar. The result revealed that soil structure was sub-angular in majority of the layers, whereas bottom layer was single grained. The value and chrome of colour was increasing in order from surface to bottom in the majority pits. Similarly, the texture was sandy loam in majority layers of the pits. Moreover, four types of consistence (loose to firm) were observed. Furthermore, mottles and gravels were absent in the majority layers. Likewise, soil was very to moderately acidic in observed layers of majority pits, except bottom layer of agronomy block was slightly acidic. Regarding fertility parameters (OM, macro and micronutrients), some were increasing and vice-versa, while others were intermittent also. Therefore, a single layer is not dominant for particular soil physico-chemical parameters in the farm. In overall, surface layer is more fertile than rest of the layers in all the pits.

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Interstellar and interplanetary solids in the laboratory

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316005688 ◽

2015 ◽

Vol 11 (A29B) ◽

pp. 416-419 ◽

Cited By ~ 1

Author(s):

Emmanuel Dartois ◽

Ivan Alata ◽

Cécile Engrand ◽

Rosario Brunetto ◽

Jean Duprat ◽

...

Keyword(s):

Interstellar Medium ◽

Environmental Parameters ◽

Interstellar Matter ◽

Additional Information ◽

Set Constraints ◽

Physico Chemical ◽

Space Environments ◽

Chemical Conditions ◽

Extraterrestrial Material ◽

Shed Light

AbstractThe composition of interstellar matter is driven by environmental parameters and results from extreme interstellar medium physico-chemical conditions. Astrochemists must rely on remote observations to monitor and analyze the interstellar solids composition. They bring additional information from the study of analogues produced in the laboratory, placed in simulated space environments. Planetologists and cosmochemists access and spectroscopically examine collected extraterrestrial material in the laboratory. Diffuse interstellar medium and molecular clouds observations set constraints on the composition of organic solids that can then be compared with collected extraterrestrial materials analyses, to shed light on their possible links.

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Degradación microbiana in situ de tejidos foliares de gramíneas y leguminosas y su relación con indicadores de calidad nutricional

Ciencia y Tecnología Agropecuaria ◽

10.21930/rcta.vol6_num1_art:41 ◽

2005 ◽

Vol 6 (1) ◽

pp. 100

Author(s):

Diego Chamorro ◽

Juan Evangelista Carulla ◽

Pablo Cuesta

Keyword(s):

Nutritional Quality ◽

Dry Matter ◽

Neutral Detergent Fiber ◽

Dry Matter Degradation ◽

Leaf Tissues ◽

Dry Seasons ◽

Stylosanthes Scabra ◽

Negative Relationships

Para cuantificar la degradación in situ de tejidos vegetales y su relación con la composición química de especies forrajeras se seleccionaron láminas foliares de las gramíneas Bouteloua repens y Bothriochloa pertusa y foliolos de las leguminosas Stylosanthes scabra, Desmodium barbatum y Tephrosia cinerea. En el rumen se incubaron muestras de 10 mm de largo durante 0, 12, 24, 48 y 72 horas; para la lectura del área residual se digitalizaron ocho tejidos. A las 24 y 48 h de incubación B. pertusa presentó relaciones positivas entre la degradación de la epidermis adaxial (EA) y la FDN (R2= 90,2), entre el mesófilo y la DIVMS (R2=80,1), y entre los tejidos lentamente degradables (TLD) y la FDA (R2= 83,9); y relaciones negativas entre EA y DIVMS (R2= –73,1), los TLD con la DEF (R2= –74,3), la EA con la PC (R2= –87,6), y el esclerenquima con la DIVMS y la PC (R2= –84,3 y R2= –90,8). Después de 72 horas de incubación las mayores áreas residuales en gramíneas fueron la estructura kranz entre 34,2% y 36,5%, el mesófilo entre 20,9% y 21,4%, el xilema de 11,5% a 17,1% y la EA entre 11,8% y 13,9%; no obstante el esclerénquima se relacionó estrechamente con indicadores de calidad nutricional. Las gramíneas obtuvieron mayores porcentajes de tejidos no degradables que las leguminosas; por lo tanto, la DIVMS y la DEF fueron menores. Entre las leguminosas, S. scabra, presentó la mayor digestibilidad de los tejidos rápidamente degradables, tanto en sequía como en lluvia; en la época seca se incrementó en 134,6% la degradación de estos tejidos. Adicionalmente, en esta especie el área residual de los taninos no presentó relación directa con la degradación del mesófilo. En leguminosas la tasa y extensión de la degradación de las epidermis se incrementaron marcadamente a mayor tiempo de incubación, presentándose diferencias entre especies, situación que no exhibieron las gramíneas. En D. barbatum la degradación de la EA se asoció con la DIVMS y la DEF, explicando en 77,4% y 72,95% estos porcentajes; de igual manera se reportaron relaciones negativas entre la degradabilidad de la epidermis y los porcentajes de FDN, FDA, lignina y taninos (R2= –0,76; R2= –0,79; R2= –0,53 y R2= –0,76, respectivamente). Microbial in situ degradation of grasses and legumes leaf tissues and its realtionship with nutritional quality and precipitationA study was conducted to measure the in situ de- gradation of plant tissues and its relationship with forage chemical composition in leaves of the grasses Bouteloua repens and Bothriochloa pertusa and of the legumes Stylosanthes scabra, Desmodium barbatum and Tephrosia cinerea. Forage samples of 10 mm in length were incubated in the rumen for 0, 12, 24, 48 and 72 h and tissue residual area was determined by reading the residual area in eight digitalized leaf samples per forage. In B. pertusa, after 24 and 48 h of incubation there were positive relations between the degradation of adaxial epidermis (AE) and the neutral detergent fiber (NDF, R2 = 90.2), between mesophyll and in vitro dry matter degradability (IVDMD, R2 = 80,1), and between slowly degradable tissues (SDT) and the acid detergent fiber (ADF, R2 = 83.9); and negative relationships between AE and IVDMD (R2 = -73,1), between SDT and effective dry matter degradation (EDMD, R2 = -74,3), between AE and crude protein (CP, R2 = -87,6), and between sclerenchyma and IVDMD with CP (R2 = -84,3 and R2 = -90,8, respectively). After 72 h of incubation, the greater residual areas in grasses were the Kranz structure (34.2% to 36.5%), mesophyll (20.9% to 21.4%), xylem (11.5% to 17.1%) and AE (11.8% to 13.9%). The area of sclerenchyma was related closely to indicators of nutritional quality. Overall, the grasses had greater content of non-degradable tissues than the legumes; therefore, their IVDMD and EDMD were lower. Among the legumes, S. scabra showed the greater digestibility of rapidly degradable tissues, both during the rainy and dry seasons. At the dry season, the degradation of these tissues increased by 134.6%. Additionally, in this legume, the content of tannins did not have a direct relationship with the degradation of mesophyll. The rate and extension of the degradation of epidermis in legumes, were noticeably increased with increasing length of incubation, existing differences between species, a situation which was not observed in the grasses. In D. barbatum, the degradation of the AE was positively associated with both the IVDMD and EDMD (R2 = 77,4% and 72,95%, respectively). On the other hand, the degradability of epidermis and the percentage of NDF had negative relations with ADF, lignin and tannins (R2 = -0,76; R2 = -0,79; R2 = -0,53 and R2 = -0,76, respectively).

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Water Birds as Indicators of Ecological Conditions in a Ramsar Wetland (Sebkhet Bazer, East of Algeria)

Agricultural Science Digest - A Research Journal ◽

10.18805/ag.d-334 ◽

2021 ◽

Author(s):

Sabrina Djerboua ◽

Sofia Djerdali ◽

José Guerrero-Casado ◽

Abdelkrim Si Bachir ◽

Ali Guendouz

Keyword(s):

Water Body ◽

Linear Models ◽

Abiotic Factors ◽

Bird Community ◽

Ecological Indicator ◽

Bird Abundance ◽

Seasonal Differences ◽

Water Bird ◽

Physico Chemical ◽

Water Birds

Background: Wetlands are the highly complex ecosystems due to various interactions between the components, where, the most iconic of ecological changes are the water birds. The current study was aimed to examine the interactions between the water birds diversity, abundance and the abiotic factors in Sebkhet Bazer. Methods: The investigation was conducted between March 2013 and December 2014 in Sebkhet Bazer (Sétif, Algeria, 36°05'N and 5°45'E), by monitoring water birds abundance (grouped into 4: Anatidae, Rallidae, Phoenicopteridae and Shorebirds) and measuring the physico-chemical water parameters (depth, temperature, pH, salinity and vegetation cover). All statistical analysis was performed using the InfoStat software (2017), it was carried out in two steps, by testing of fixed linear models; first of the seasonal differences in water body variables and second of the seasonal differences in bird abundance for the 4 water bird groups. Result: The results showed that the physico-chemical parameters of water varied considerably from season to season. The four groups of birds reached their lowest abundance in summer, with Rallidae and Phonicopteridae being more abundant in spring, Anatidae in winter and Shorebirds in autumn, suggesting that this variation is attributed to changes in water body characteristics between the four seasons. Therefore, the abundance of the different water bird group could be used as an ecological indicator of this wetland’s characteristics. If these features are altered by climate change, the water bird community would be also affected.

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