Wyniki wyszukiwania - BazTech

1

Control mechanisms on the reactive silicate fluxes by using on board resuspension experiments in the eutrophicated coastal environment

Özkan Ebru Y., Buyukisik Hasan B.

Oceanological and Hydrobiological Studies

|

2023

|

Vol. 52, No. 3

343--365

EN

This study aims to differentiate bio-mediated and biogenic CO3-2precipitation or terrestrial CO3-2 input using on board incubation techniques, to investigate the effects of resuspension in the coastal environment and to increase our understanding of predicted relationships between silicate releases and other biogeochemical variables in resuspension events. Relationships between dark silicate flux and BSi, CO3-2, OrgC, Mn (manganese) according to the seasons were examined. The silica flux is controlled by the CaCO3 coating on the diatom skeletons due to the fact that diatom skeletonsact as crystallization nuclei in the calcite precipitation that is biologicallya ffected. The reduction in flux with BSi may be due to the reduction in thesurface areas of larger diatom species. The negative linear relationships observed between silica fluxes and CO3-2 is indicative of RSi fluxes constrainedby bio-mediated carbonate increase. Linear relationships which are the samein their slopes but differ in their intercepts, reveal the effect of the changein diatom size on silica flux. Smaller diatoms have more surface area perunit volume, meaning an increased silica flux. On the other hand, seeing different CO3-2 values at stations with the same orgC value have increased the confidence interval (CI) 95% in the linear relationship. The presence ofdifferent silica flux values in stations with the same carbonate value may beexplained both by different orgC values and by diatoms containing different group sizes. The silica flux is controlled by the CaCO3

2

Response patterns of phytoplankton growth to variations in resuspension in the German Bight revealed by daily MERIS data in 2003 and 2004

Su J., Tian T., Krasemann H., Schartau M., Wirtz K.

Oceanologia

|

2015

|

No. 57 (4)

328--341

EN

Chlorophyll (chl a) concentration in coastal seas exhibits variability on various spatial and temporal scales. Resuspension of particulate matter can somewhat limit algal growth, but can also enhance productivity because of the intrusion of nutrient-rich pore water from sediments or bottom water layers into the whole water column. This study investigates whether characteristic changes in net phytoplankton growth can be directly linked to resuspension events within the German Bight. Satellite-derived chl a were used to derive spatial patterns of net rates of chl a increase/decrease (NR) in 2003 and 2004. Spatial correlations between NR and mean water column irradiance were analysed. High correlations in space and time were found in most areas of the German Bight (R2 > 0.4), suggesting a tight coupling between light availability and algal growth during spring. These correlations were reduced within a distinct zone in the transition between shallow coastal areas and deeper offshore waters. In summer and autumn, a mismatch was found between phytoplankton blooms (chl a > 6 mg m−3) and spring-tidal induced resuspension events as indicated by bottom velocity, suggesting that there is no phytoplankton resuspension during spring tides. It is instead proposed here that frequent and recurrent spring-tidal resuspension events enhance algal growth by supplying remineralized nutrients. This hypothesis is corroborated by a lag correlation analysis between resuspension events and in-situ measured nutrient concentrations. This study outlines seasonally different patterns in phytoplankton productivity in response to variations in resuspension, which can serve as a reference for modelling coastal ecosystem dynamics.

3

Influence of the winter phytoplankton bloom on the settled material in a temperate shallow estuary

Guinder V. A., López-Abbate M. C., Berasategui A. A., Negrin V. L., Zapperi G., Pratolongo P. D., Fernández-Severini M. D., Popovich C. A.

Oceanologia

|

2015

|

No. 57 (1)

50--60

EN

The development of the phytoplankton winter bloom and the accumulation of particulate suspended matter (PSM) inside sediment collectors were assessed in the inner zone of the Bahía Blanca Estuary. The phytoplankton bloom (chlorophyll up to 25 μg l-1 and abundance up to 8 × 106 cells l-1) was related with high levels of dissolved inorganic nutrients and underwater light availability (Im up to 355 μE m-2s-1) and was dominated by relatively small diatoms, e.g. Chaetoceros sp.1 (3–8 μm). Conversely, large planktonic diatoms, mostly Thalassiosira spp. 20–60 μm, were found in the accumulated material inside the collectors, together with benthic microalgae and high concentrations of chlorophyll, phaeopigments, particulate organic matter (POM between 18 and 32% of total PSM) and C:N ratios >12. The composition of the settled material indicated vertical exportation of phytoplankton to the benthos, external loads of detritus and bottom resuspension. The present study highlights the close benthic‐pelagic interactions in shallow coastal environments characterized by high productivity.

4

Influence of the wind field on the radiance of a marine shallow: evidence from the Caspian Sea

Karabashev G. S., Evdoshenko M. A.

Oceanologia

|

2012

|

No. 54 (4)

655-673

EN

The influence of the near-water wind field on the radiance of a marine shallow was studied on the basis of daily SeaWiFS ocean colour scanner data and QuickScat scatterometer wind data collected from 1999 to 2004 in the southern Caspian Sea, where the deep basin borders a vast shallow west of the shore of meridional extent. It was found that radiance distributions, clustered by wind rhumbs, exhibited different long-term mean patterns for winds of opposing directions: within the shallow's boundaries, the radiances were about twice as high for winds having an offshore component with reference to the onshore wind conditions. The zonal profile of radiance across the shallow resembled a closed loop whose upper and lower branches corresponded to the offshore and onshore winds respectively. The loop was the most pronounced at sites with 10-15 m of water for any wavelength of light, including the red region. On the basis of specific features of the study area, we attributed this pattern to sunlight backscattered from bottom sediments resuspended by bottom compensation currents induced by the offshore winds.

5

Otrzymywanie i właściwości kompozytowych cząstek proszków do inhalacji

Odziomek M., Sosnowski T. R., Gradoń L.

Inżynieria i Aparatura Chemiczna

|

2010

|

Nr 2

91-92

PL

Celem pracy było wytworzenie metodą suszenia rozpyłowego cząstek nośnika proszkowych leków do inhalacji, charakteryzujących się wielkością poniżej 5 urn oraz cechami powierzchniowymi, ułatwiającymi ich de-agregację. Wykazano, że dzięki sterowaniu warunkami procesu i składem roztworu poddawanego suszeniu (dodatek aminokwasu, białka, polimeru) można uzyskiwać cząstki o różnej morfologii. W niektórych przypadkach prowadzi to do korzystnego wzrostu udziału frakcji drobnocząstkowej w rozpylonym proszku.

EN

Work is focused on spray-drying production of drug-carrier particles suitable for inhalation (size below 5 um, low cohesivity). Particles with different morphology can be obtained with the adequate control of process parameters and the composition of sprayed solution (amino-acid, protein or polymer additives). It was shown that changes of particle morphology lead in some cases to a better powder resuspension in a dry powder inhaler.

6

Climate of long internal waves and resuspension on the coastal shelf

Bogucki D.J., Redekopp L.G.

Oceanologia

|

2008

|

No. 50 (1)

5-21

EN

Observations of the shelf environment rarely associate internal solitary waves (ISWs) with the impact of their passage. An experiment observed during the Coastal Mixing and Optics 1996 (CMO '96), a sequence of long internal waves on a coastal shelf is reported, including both mode-1 and mode-2 waves, together with evidence related to the interaction of propagating ISWs and the benthic boundary layer. The observed ISW dynamics is shown to present a repetitive pattern or "climate cycle". The ISW-associated benthic signature described here occurs frequently (at least once a day) in the CMO '96 coastal area and suggests that ISWs under calm, summer-like conditions may have a decisive influence on the fate of near-bottom pollutants or biological processes in shelf regions.

7

Balance and circulation of nutrients in a shallow coastal Lake Gardno (North Poland)

Trojanowski J., Trojanowski C.

Archiwum Ochrony Środowiska

|

2007

|

Vol. 33, no. 1

45-57

EN

In 2002 the circulation of nutrients and their balance was studied in a large, shallow, eutrophic Lake Gardno. It was determined that throughout a year 1516 Mg of total nitrogen and 155 Mg of total phosphorus reach the lake. Approximately 67% of nitrogen and 87% of phosphorus reaching the lake flows out of it, the rest remains in the lake. About 45% of the total loss of nitrogen results from denitrification, and about 53% from sedimentation. The greatest effect on the circulation of nutrients in Lake Gardno is exerted by the mixing of water caused by strong winds resulting in the upward movement of the surface layers of bottom sediments. This causes increased resuspension and sedimentation, which mask similar processes resulting from the outer load of nutrients and from autochtonie processes and products, which are one or two orders of a magnitude smaller.

PL

W 2002 roku w jeziorze Gardno badano krążenie substancji biogenicznych w profilu pionowym i horyzontalnym oraz oszacowano bilans tych składników. Eutroficzne jezioro Gardno leży w strefie przybrzeżnej Bałtyku i charakteryzuje się dużą powierzchnią oraz niewielką głębokością (średnio 1,6 m). Stwierdzono, że w ciągu roku do jeziora dostaje się 1516 Mg azotu ogólnego i 155 Mg fosforu ogólnego. Z tego 67% azotu i 87% fosforu wypływa z niego poprzez odpływ, a reszta pozostaje w jeziorze. Z pozostającego w jeziorze azotu 45% uwalnia się poprzez proces denitryftkacji, a 53% ulega sedymentacji. Największy wpływ na krążenie związków tych dwóch pierwiastków ma mieszanie się wody wywołane silnymi wiatrami. Przemieszczające się masy wody porywają wierzchnią warstwę osadów dennych i mieszają się z nią. Powoduje to zwiększenie resuspensji i sedymentacji, maskując podobne procesy wynikające z zewnętrznego ładunku substancji biogenicznych oraz procesów i produktów autochtonicznych, które co do wielkości są o jeden, dwa rzędy mniejsze.

8

Wpływ aranżacji przepływu powietrza na proces aerozolizacji leków

Sosnowski T. R., Gradoń L., Smolińska A.

Inżynieria i Aparatura Chemiczna

|

2006

|

Nr 5s

123-125

EN

Resuspension of powder by airflow was investigated experimentally and numerically (CFD). The aerosol emission efficiency and particle size distribution were measured as a function of airflow rate and flow arrangement in a vicinity of the powder layer. The pressure drop values for tested flow configurations were measured. The research results confirmed that aerodynamic conditions had a significant impact on the concentration and particle size distribution of the aerosol produced from powder. These factors determine potential applications of the given resuspension system in medical inhalers.

9

Zastosowanie metody lattice-Boltzmann do opisu struktury materiału zdeponowanego w filtrach włókninowych

Przekop R., Moskal A., Gradoń L.

Inżynieria i Aparatura Chemiczna

|

2003

|

Nr 1

31-32

EN

The cellular automata probabilistic model extended to the lattice- Boltzmann approach was used for description of the local structures of deposited particles forming clusters on the surface of a single fibre of the filter. The fractal dimension of deposited structure and its local porosity were calculated for the Peclet number ranging from 0.5 to 10. The possibility of resuspension was taken into account.

10

Oscylacyjny model cząstek aglomeratu proszkowego

Grzybowski K., Moskal A., Przekop R., Gradoń L.

Inżynieria i Aparatura Chemiczna

|

2003

|

Nr 1

10-11

EN

The structural stability of the powder layer depends on the relation between adhesive and separation forces acting on each particles of the powder structure. We proposed an oscillating model of particles interactions, which described this structure. It was used to write a computer program simulated particles resuspension from powder into fluid. Results of the simulation are presented.