irena ciglenecki - Academia.edu (original) (raw)

Papers by irena ciglenecki

Estuarine, Coastal and Shelf Science

Science of The Total Environment

Estuarine, Coastal and Shelf Science, 2021

Seasonal blooms of the invasive ctenophore Mnemiopsis leidyi have been recorded throughout the Ad... more Seasonal blooms of the invasive ctenophore Mnemiopsis leidyi have been recorded throughout the Adriatic Sea, affecting the ecosystem and its pelagic resources. Gelatinous organisms such as M. leidyi release significant quantities of excreta as labile and surface active dissolved organic carbon (DOC) that supports the microbial activity. The effects of M. leidyi's presence on heterotrophic prokaryotes (HP), cyanobacteria (CB) and heterotrophic nanoflagellates (HNF) were investigated at five locations in the coastal waters of Rovinj-Rovigno (northern Adriatic) during intensive blooms in September 2019. Additionally, circulation in the study area was examined using available current measurements and a hydrodynamic model. In September, low-pass filtered currents near the surface were mostly directed toward S-SE reaching 25 cm/s, indicating the presence of the Istrian Coastal Countercurrent (ICCC). Ctenophores displayed a patchy spatial distribution from 0.05 to 100 M. leidyi individuals per m 3. When ctenophore density in the swarms surpassed 1 individual per m 3 , the change in the abundances of microbial groups became evident. The lowest microbial densities and lowest concentrations of dissolved and particulate organic carbon (DOC and POC) and surface-active substances occurred in the absence of M. leidyi, while the highest were within the swarms. We hypothesise that HP utilises the available DOC enhancing the remineralisation of organic matter. Finally, greater availability of HNF's prey (HP and CB) leads to an increase in their abundance. This study illustrates how the release of surface-active DOC during intensive M. leidyi's blooms can stimulate the microbial loop. The current system with the ICCC prevailing in September enables the spreading of M. leidyi from its hypothetic origin in an open sea gyre towards the coast. Bora wind episodes may initiate and favour this type of circulation. In these conditions, M. leidyi agglomerates in large numbers along the coast, enabling the accumulation of organic matter and altering the abundance of pico-and nanoplankton.

Hrvatske vode u zaštiti okoliša i prirode, 7. hrvatska konferencija o vodama, 2019

&lt;p&gt;Lake Rogoznica (also known as "Dragon's Eye") ... more &lt;p&gt;Lake Rogoznica (also known as "Dragon's Eye") is a karstic, marine lake on the Gradina peninsula located at the Adriatic coast at 43&amp;#176; 32' N and 15&amp;#176; 58' E. Most of the time the lake is stratified, with an upper oxic layer, an anoxic bottom layer, and a chemocline in between. Every few years the stratification suddenly breaks down and the entire water column becomes mixed, anoxic, and euxinic, with HS&lt;sup&gt;-&lt;/sup&gt; presence throughout the water column. This leads to mass mortality of aerobic populations in the lake, which require long periods of time without mixing to recover. Rogoznica residents confirmed that the sudden overturning of layers had been occurring even before continuous research began in 1992, but also that it used to happen less frequently. In the last 30 years, five such events of complete anoxia have been recorded: in September 1997, October 2011, October 2016, October 2020, and October 2021. As the sudden mixing now occurs year after year, the lake's ecosystem does not have nearly enough time to recover. Previous work has indicated that the main trigger for the abrupt mixing is a sudden drop in surface temperature caused by an overpassing low-pressure system. Nevertheless, the process of overturning and sudden release of bottom-layer sulfides is a very delicate one, and determining other biological, physical, and chemical triggers is an important question that remains to be answered. Another key question is whether the increase in the overturn frequency is solely a part of the natural life cycle of the lake, a result of the changing climate with more extreme weather events, or a more direct consequence of human activities in the area.&lt;/p&gt;&lt;p&gt;Comparison of the most recent water level measurements from June 2021 with those from 2013 indicate that the tidal signal in the lake requires a somewhat different analytical approach than the standard ocean tidal analysis procedure. Moreover, measurements at the boundaries of the lake show that the water entering the lake from the karst at high tide is not only colder but also has a lower salinity. Additionally, in this work we present new insights into the physicochemical properties of the lake's water column (&amp;#963;&lt;sub&gt;T&lt;/sub&gt;-stratification, dissolved oxygen concentration) and the direct influence of atmospheric wet deposition on the lake's surface layer.&lt;/p&gt;

Zvornik 10th ISE Satellite Student Regional Symposium on Electrochemistry BOOK OF ABSTRACTS, 2021

The appearance of mucilages in the Adriatic as well as more frequently in other coastal waters ar... more The appearance of mucilages in the Adriatic as well as more frequently in other coastal waters around Europe are basis of many laboratory and field studies with the aim of finding out the origin and causes of this phenomenon. A novel definition consider mucilage aggregate like an anomalous accumulation of organic matter produced by several marine organisms depending on the peculiar climatic conditions which are known to support the mucilage formation1. Namely, conditions such as hot springs and summers, following mild winters with reduced rates of marine current and wave motion resulting in anoxic conditions along the water column was observed during the last appearance of the mucilages in the Adriatic Sea2. In the field studies diatoms are found to be the major producers of mucilagionus material. Diatoms are known to produce copius amounts of colloidal mucus and other exopolymeric material3. This colloidal mucus by processes of aggregation, coagulation and flocculation are transfer...

Environmental Research, 2021

Surface active substances (SAS) have a potential to form films at different interfaces, consequen... more Surface active substances (SAS) have a potential to form films at different interfaces, consequently influencing the interfacial properties of atmospheric particulate matter (PM). They can be derived from both human activities and natural processes, and can be found in an indoor and outdoor environment. This paper's fundamental question is possible role of the SAS in stabilizing respiratory aerosols in the closed space. In that context, we discuss results of preliminary measurements of the SAS and dissolved organic carbon (DOC) concentrations in the water-soluble fractions of PM2.5 and PM10 that were sampled simultaneous in primary school inside and outside of the building. The concentrations of SAS were determined using highly sensitive electrochemical measurements. It was observed that SAS and DOC concentrations have been enhanced indoor in both PM fractions. Consistent with these results, a discussion arises on the possibility that SAS could play a crucial role in respiratory droplet dispersion as stabilizers, especially in a closed space. At the same time, we assume that they could prolong lifetime of respiratory aerosols and as well viability of some (possible SARS-CoV-2) virus inside of the droplets.

Croatian Science Foundation MARRES project (MARine lake (Rogoznica) as a model for EcoSy... more Croatian Science Foundation MARRES project (MARine lake (Rogoznica) as a model for EcoSystem functioning in a changing environment) aims to investigate the unique environment (slow exchange of seawater with the sea; atmospheric input is the only source of freshwater) of the marine lake which is an example of highly stratified (permanent anoxia bellow 9 m depth), and by climate changes affected marine system in the middle of the eastern Adriatic coast (43.53° N, 15.95° E). The area of the lake is characterized by the extensive tourism and mariculture, and the low impact of local industrial activities. It is also affected by the combined influence of long-range transport of air masses and local emissions (open-fire events).An important part of the project is focused on the exchange and interaction between atmosphere, water column and sediment by measuring the atmospheric input (wet and dry deposition) of sulphur compounds, organic carbon, trace metals and radionuclides (Be-7, Pb-210).This work for the first time will present the current state of the measurements of radioactivity in the Rogoznica lake area, including samples of aerosol particulate matter, PM2.5 < 2.5 um, rainwater and lake water column. Namely, the concentrations of Be-7 and Pb-210 in PM2.5 are measured to determine and correlate the dynamics of particle transport, meteorological information, especially origin of air masses and seasonal variation of PM2.5. While presence of Be-7 indicates the recent wet or dry deposition from the upper parts of the atmosphere, Pb-210 may be used as a tracer for continental air masses. Therefore, it can also indicate the influence of the pollution induced by human activity. Regarding that, special attention will be paid to compare results before and during the Covid-19 lockdown periods.So far, preliminary results do not show significant difference in PM2.5 masses and measured radionuclide activity concentrations for the lockdown period. Be-7 and Pb-210 were regularly detected in aerosols collected on a glass fiber filters during a one-week sampling periods with the air flow rate of 2.3 m3/h. Their activity concentrations are determined by gamma spectrometry using High Purity Germanium detectors. The results are found to be correlated with PM2.5 masses, ranging from 2.9 to 12.2 Bq/m3 for Be-7 and from 0.5 to 2.5 Bq/m3 for Pb-210. First analyses show that the highest values can be related to the long-range transport of air masses and to the recorded near open-fire event. As expected, Be-7 is also detected in almost every rainwater sample (event), with the activity concentration up to 5.6 Bq/L, while low activities of Pb-210 are detected only sporadically. Related to that, Be-7 is detected in lake water column as well, but only in the surface layer and in samples collected during, or immediately after the rain events. Dynamics and seasonal variation of radionuclide activity concentrations in here studied samples will be discussed, and the relationships with some meteorological parameters (temperature, wind speed, relative humidity, precipitation level) as well as local and long-range transport and physico-chemical conditions in the lake water column will be established.

The current knowledge in aerosol science is still incapable to give a real and quantitative asses... more The current knowledge in aerosol science is still incapable to give a real and quantitative assessment of their actual impact on global climate and health. This problem arises from the fact that, until today, there is insufficient knowledge regarding aerosol sources, mechanisms of formation, aerosol properties and chemical composition. In this study, atomic force microscopy (AFM) was applied for characterization/imaging of water soluble fraction of marine aerosols. Obtained results were discussed in terms of water soluble organic matter results obtained by high temperature catalytic oxidation (HTCO) and electrochemistry. Each technique characterized different chemical components of marine aerosols and provided complementary information.

Acta Adriatica: International Journal of Marine Sciences, 2013

The calanoid copepod Acartia italica is the only metazoan plankton species surviving and reaching... more The calanoid copepod Acartia italica is the only metazoan plankton species surviving and reaching high abundance in the middle Adriatic saline coastal Lake Rogoznica. Seasonal variations in the abundance of nauplii, copepodites, adults and their faecal pellets were assessed in the period January 2000 to December 2004. Development and behaviour of A. italica were regulated by thermohaline conditions, biology (phytoplankton, bacteria, ciliates), and chemistry (organic matter, dissolved oxygen, reduced sulphur species) of the lake. The diatom Chaetoceros curvisetus could provide important food for A. italica adult specimens; however, great diatom abundances could reduce copepod reproductive ability. This study show that top-down control which characterized the lake ecosystem before the disastrous anoxia event in 1997 were re-established again.

In anoxic sediments solubility and thus toxicity of mercury is controlled by its interaction with... more In anoxic sediments solubility and thus toxicity of mercury is controlled by its interaction with sulfur and carbon cycles. The main objective of this work was to investigate speciation of mercury and sulfur in solid and dissolved phases of contaminated coastal sediments in order to elucidate interactions between theses cycles. The study was performed in the Kastela bay (located in the central part of the Eastern Adriatic coast) polluted by mercury originating from a chlor-alkali plant. The solid phase was analysed for total Hg, MeHg (methylmercury), AVS (Acid Volatile Sulfides), CRS (Chromium Reducible Sulfur), organic carbon and carbonate. The total Hg (20-60 mg/kg) and MeHg (20-50  g/kg) concentrations in a sediment core collected in October 2001 were about 100 and 10 times, respectively, higher than typically for uncontaminated marine sediments. The sediment was anoxic, rich in organic matter (50-60 g/kg) and characterised with high level of AVS already in the surface layer. Re...

Science of The Total Environment, 2020

The paper presents a unique time series of organic matter content (dissolved organic carbon, DOC,... more The paper presents a unique time series of organic matter content (dissolved organic carbon, DOC, and its surface active fraction, SAS) collected in the northern Adriatic along the Po-Rovinj transect between 1998 and 2017. The data were collected on a monthly or a bimonthly basis. Seasonal variance of organic matter content does not exceed 30% of the total variance, while the DOC and the SAS trends are significantly negative and positive, respectively, over the whole transect. The organic matter content, however, exhibits pronounced interannual and decadal changes, with periods of high and low carbon content and evident changes in reactivity regarding to the SAS type content. The changes indicate altering episodes between eutrophication and oligotrophication, embedded to the overall oligotrophication trend in the considered period. Both series were correlated to the potential local and regional yearlyaveraged drivers in both atmosphere and sea. For the DOC, the largest correlations (significant at 99%) are obtained with the Po River discharges, at the phase lag of-1 to-2 years. For the SAS, the largest correlations (significant at 99%) are obtained with the Adriatic-Ionian Bimodal Oscillating System index (BiOS index), at the phase lag of-3 to-4 years. Correlations between the organic matter content and the hemispheric or the regional patterns (North Atlantic Oscillation, East Atlantic/West Russia, East Atlantic, Scandinavian, and Mediterranean Oscillation) are much lower and only sparsely correlated at some phase lags. The same was found for the other local drivers (precipitation and net heat flux). Our previously considered to shape the biogeochemical properties of such shallow coastal regions highly impacted by the freshwater load.