Wyniki wyszukiwania - Biblioteka Nauki

1

Occurrence and distribution of bacteria decomposing organic phosphorus compounds in the surface seawater layers

100%

Mudryk Z.

Oceanological Studies

|

1998

|

tom Vol. 27, No. 3

45-55

EN

The ability of neustonic and planktonic bacteria inhabiting the Gdańsk Deep to decompose organie forms of phosphorus was studied. It was found that bacteria hydrolysed phytin and DNA most actively, while only smali percentage of bacterial strains studied was able to depolymerize glycero-phosphate. Significant differences in the intensity of minerahzation of organie phosphorus compounds between ncustonic and planktonic bacteria were observed. This process was characterised by consid-erable diel fluctuations. It was also found that in the microlayer, the activity of alkaline phosphatase was higher than of acid phosphatase.

2

Short-term changes in the hydrochemical constituents in the water column of the Gdańsk Deep (Baltic Sea) in spring. Part 2. Modelling of diel changes in nutrient concentrations in the euphotic layer

100%

Falkowska L.

Oceanologia

|

1998

|

tom No. 40 (2)

105-115

EN

The paper deals with the diel fluctuations of nutrient concentrations and oxygen in the euphotic layer of the Gdansk Deep in spring in the years 1989-1996. Using non-linear regression, these diel variations were modelled under a variety of typically spring density stratifications: in the absence of thermal layering, in the presence of a distinct thermocline and during thermocline formation. The diel cycle of nutrients in the euphotic layer showed two maxima and two minima, probably due to variability in photosynthetic intensity.

3

Anomalies in the physical and chemical structure of the Gdańsk Deep caused by groundwater seepage

100%

Falkowska L.

Oceanologia

|

1998

|

tom No. 40 (2)

71-82

EN

Seepage of freshwater into the near-bottom layer (ca 100m depth) of the Gdansk Deep was reported during short-term studies on the variations of concentration of chemical compounds and the stratification of this basin. As a result, the salinity fell to below 1 PSU and the temperature rose from 5 to ca 7.5oC in this layer; further consequences were changes in the chemical and hydrological stratification throughout the water column. Directly above the area of seepage there was a zone of powerful turbulent convection where the temperature-salinity Rayleigh number was of the order of 10^16. Large quantities of suspended matter and poorly oxygenated deep waters were carried by the convection current from below the halocline up to the sea surface. This seepage of groundwaters is probably a continual and not an intermittent phenomenon.

4

Short-term changes in the hydrochemical constituents in the water column of the Gdańsk Deep (Baltic Sea) in spring. Part 1. Nutrient and oxygen concentrations in relation to the density stratification

88%

Falkowska L. , Burska D. , Bolałek J.

Oceanologia

|

1998

|

tom No. 40 (2)

83-104

EN

Both the seasonal thermocline in the uppermost layer of the sea and the halocline in the near-bottom layer were found to constrain transport of chemical compounds to the productive layer of the Gdansk Deep. The occasional disappearance of the halocline resulted on the one hand in the flow of nitrogen and phosphorus compounds through the intermediate layer towards the surface, and on the other in a considerable improvement in oxygen conditions in the near-bottom layer, this usually being either poorly oxygenated or anoxic. A statistically significant negative correlation between nitrate and oxygen concentrations was found in the isohaline layer. The N:P ratio was usually low during the day but increased at night. During spring this ratio increased in the euphotic layer. The large number of high N:P ratios may attest to the shortage of phosphates and to the change in the limiting factor - from nitrogen compounds in early spring to phosphates in late spring.

5

Parameterisation of a population model for Acartia spp. in the southern Baltic Sea. Part 2. Egg production

88%

Dzierzbicka-Głowacka L. , Lemieszek A. , Żmijewska M. I.

Oceanologia

|

2009

|

tom No. 51 (2)

185-201

EN

The paper describes the modelling of egg production in Acartia spp. under changing environmental conditions in the southern Baltic Sea (Gdańsk Deep). The hypothesis (Sekiguchi et al. 1980) that the food-saturated rate of egg matter production is equivalent to specific growth rate of copepods is applied. The average number of eggs produced per day by one Acartia female is obtained as a function of growth rate, i.e. by multiplying exp gN3-1 from the growth rate of the nauplius stage equation by Wfemale / Wegg. The copepod model, reduced to a zero-dimensional population model calibrated for Acartia spp. under the environmental conditions typical of the southern Baltic Sea, was used to determine the effects of temperature and food concentration on the growth rate of each of the model stages (see Part 1 - Dzierzbicka-Głowacka et al. 2009 - this issue). In this part, egg production as a function of the above parameters is evaluated. The rate of reproduction during the seasons in the upper layer of the Gdańsk Deep is also determined.

6

Parameterisation of a zero-dimensional pelagic detritus model, Gdańsk Deep, Baltic Sea

63%

Kuliński K. , Maciejewska A. , Dzierzbicka-Głowacka L. , Pempkowiak J.

|

tom Tom 13

187-206

EN

This paper presents a zero-dimensional particulate detritus model (Figure 1) and a comprehensive description of parameterisation processes that influence the non-living organic matter (detritus) concentration in the whole water column. Mathematically, the particulate pelagic detritus concentration can be described as a variable dependent on the number of its sources and sinks. Temporal supplies in the pelagic detritus concentration are affected by the natural mortality of phytoplankton and zooplankton as well as by the faecal pellets that enter the detritus pool. On the other hand, sedimentation, grazing of detritus by zooplankton and mineralization of pelagic detritus act as sinks that reduce the detritus concentration in the water column. The aim of this model study was to calibrate the detritus model under the environmental conditions typical of the Gdańsk Deep in the southern Baltic Sea.

PL

Przedmiotem badań jest parametryzacja zero wymiarowego Modelu Detrytusu Pelagicznego (PDM). Stężenie detrytusu pelagicznego w wodzie morskiej jest determinowane równowagą ustaloną pomiędzy źródłami i ubytkami martwej, zawieszonej materii organicznej. Do źródeł zalicza się: śmiertelność fito- i zooplanktonu oraz odchody zooplanktonu. Wśród ubytków detrytusu wyróżnić można natomiast sedymentację, wyżeranie przez zooplankton oraz rozkład biochemiczny. Przedstawione badania opisują oddziaływanie temperatury, stężenia związków biogenicznych, nasłonecznienia oraz biomasy fito- i zooplanktonu na stężenie detrytusu pelagicznego w wodzie morskiej. Parametryzacja przeprowadzona została w typowych dla południowego rejonu Morza Bałtyckiego zakresach zmiennych. Detrytus pelagiczny razem z fito- i zooplanktonem są komponentami niezbędnymi do opisania zmienności stężeń zawieszonego węgla organicznego (POC) będącego istotnym składnikiem obiegu węgla w środowisku morskim. Prawidłowa parametryzacja PDM stanowi zatem podstawę dla numerycznego opisu aktualnej i przyszłej zmienności stężeń POC w wodzie Morza Bałtyckiego.

7

DOC and POC in the water column of the southern Baltic. Part I, Evaluation of factors influencing sources, distribution and concentration dynamics of organic matter

51%

Maciejewska A. , Pempkowiak J.

|

tom No. 56 (3)

523--548

EN

Organic substances are important components of the marine environment as they determine the properties of seawater and the key biogeochemical processes taking place in it. Organic carbon (OC) is a measure of organic matter. For practical purposes, OC is divided into dissolved organic carbon (DOC) and particulate organic carbon (POC). Both DOC and POC play a major role in the carbon cycle, especially in shelf seas like the Baltic, where their concentrations are substantial. In a three-year study (2009-2011) seawater samples for DOC and POC measurements were collected from stations located in the Gdańsk Deep, the Gotland Deep and the Bornholm Deep. The accuracy and precision of analysis were satisfactory; the recovery was better than 95%, and the relative standard deviation was 4% (n = 5). Concentrations of chlorophyll a, phaeopigment a, salinity, pH and temperature were also measured in the same samples. These parameters were selected as proxies of processes contributing to DOC and POC abundance. The aim of the study was to address questions regarding the vertical, horizontal and seasonal dynamics of both DOC and POC in the Baltic Sea and the factors influencing carbon concentrations. In general, the highest concentrations of both DOC and POC were recorded in the surface water layer (DOC ~4.7 mg dm-3, POC ~0.6 mg dm-3) as a consequence of intensive phytoplankton activity, and in the halocline layer (DOC ~5.1 mg dm-3, POC ~0.4 mg dm-3). The lowest DOC and POC concentrations were measured in the sub-halocline water layer, where the values did not exceed 3.5 mg dm-3 (DOC) and 0.1 mg dm-3 (POC). Seasonally, the highest DOC and POC concentrations were measured during the growing season: surface DOC ~5.0 mg dm-3; sub-halocline DOC ~4.1 mg dm-3 and surface POC ~0.9 mg dm-3, sub-halocline POC ~0.2 mg dm-3. The ANOVA Kruskal-Wallis test results indicate statistically significant differences among the three study sites regarding average concentrations, and concentrations in particular water layers and seasons. It shows that concentrations of DOC and POC differ in sub-basins of the Baltic Sea. The differences were attributed to the varying distances from river mouths to study sites or the different starting times and/or durations of the spring algal blooms. Statistically significant dependences were found between both DOC and POC concentrations and Chl a (phytoplankton biomass), pH (phytoplankton photosynthetic rate), pheo (zooplankton sloppy feeding), salinity (river run-off and North Sea water inflows) and water temperature (season). This was taken as proof that these factors influence DOC and POC in the study areas.