Wyniki wyszukiwania - BazTech

1

Seasonal changes in particulate organic matter (POM) concentrations and properties measured from deep areas of the Baltic Sea

Winogradow Aleksandra, Mackiewicz Anna, Pempkowiak Janusz

Oceanologia

|

2019

|

No. 61 (4)

505--521

EN

In seawater particulate organic matter (POM) serves as a food source for heterotrophic bacteria and zooplankton and is a source of dissolved organic compounds and nutrients. POM plays a critical role in transporting carbon to marine sediments where a fraction of it is buried in subsurface sediments and thus avoids conversion to carbon dioxide on shorter time scales. Distribution and properties of POM were investigated in the Baltic Proper from 2013 to 2015. Particulate organic carbon (POC) was used to investigate POM sources and dynamics. Stable carbon isotopes (δ13C), elemental composition (C, N), chlorophyll a and POM contribution to suspended particulate matter (SPM) were also measured and interpreted. The water column exhibited concentrations ranging from 0.2 mg POC/l (deep water layer — DWL, cold season — CS) to 1.7 mg POC/l (surface water layer — SWL, warm season — WS). POM represented 0.15 to 0.45 of SPM during respective cold and warm seasons. Stable carbon isotopes (δ13CPOC) ranged from -22.5‰ (WS) to -28.0‰ (CS), while the POC/Chl a ratio ranged from 180 g/g (SWL-WS) to 300 g/g (DWL-CS). Seasonal changes were attributed to high primary production in the SWL during the WS, which represented a major POM source. Continuous mineralization/sedimentation through-out the water column constituted a major POM sink.

2

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

Maciejewska A., Pempkowiak J.

Oceanologia

|

2014

|

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.

3

Acoustic experiment on diel fish behaviour cycle performed in the Gotland Deep

Orlowski A.

Hydroacoustics

|

2003

|

Vol. 6

19--30

EN

This paper describes the results of 24 h acoustic experiment based on three-dimensional measurements of the S; distribution of herring and sprat in the southern Baltic in October 2001. The experiment was based on a continuous (24h day) integration offish echoes using an EY500 echo sounder from a vessel with a constant speed of 8 knots, moving along the sides of a square equal to 4 n.mi., localized inside the specified area. Duration of the experiment was limited by deterioration of the weather conditions but nearly 300 ESDU samples were collected. These are correlated with values of coincident environmental factors: time, depth, water temperature, salinity and oxygen levels; estimated on the basis of survey data. Fish behaviour vs environmental factors is described by different macrosounding visualizations, statistical, and mathematical models. The purpose of the paper is to compare results of the experiment to the average characteristics of fish behaviour in the same basin, based on autumn studies over the period 1995-2001. General analysis was provided for the selected area of the Polish EEZ (south Gotland Deep), characterized by the greatest depth movements of fish diel migration. The most significant differences were found between fish migration pattern and diel stability of the acoustic response between these situations, specially during the sunset period.

4

Chlorins in sediments of the Gotland Deep (Baltic Sea)

Kowalewska G., Winterhalter B., Talbot H. M., Maxwell J. R., Konat J.

Oceanologia

|

1999

|

No. 41 (1)

81-97

EN

The distributions of chlorin components as well as chlorophylls c and β-carotene in postglacial sediments (down to ca 5 m depth), collected from the Gotland Deep in July 1997, have been determined. The major pigments were similar to those identified in recent (0–10 cm) sediment extracts of the Gdansk Deep. High amounts of well preserved chlorins, including intact chlorophyll a, provide evidence for high primary production in the past, anoxic sedimentation and favourable postdepositional conditions. In addition, the results reveal several extremely rapid changes in the Baltic environment over the last 8000 years caused by different physico-chemical conditions and subsequent changes in phytoplankton occurrence, biomass and algal species.