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Size-fractionated chlorophyll a and phycocyanin temporal variations in a highly eutrophic lake and its isolated karstic springs

Tsola S. L., Renta C., Macingo S. C., Karayanni H.

Oceanological and Hydrobiological Studies

2018

Vol. 47, No. 2

118--127

Monthly variations of size-fractionated chlorophyll a and phycocyanin were studied in Lake Pamvotis between August 2016 and January 2017. Sampling was conducted at two sampling sites: in the main lake (Site 1: Lake) and in an adjacent man-made water ski lake with karstic springs (Site 2: Springs). Samples were fractionated into three size classes: 0.2–2 μm (pico), 2–20 μm (nano) and 20–180 μm (micro). According to chlorophyll a values, eutrophic to hypereutrophic conditions prevail at Site 1 and oligotrophic to mesotrophic conditions – at Site 2. Similarly, Site 1 was distinguished by higher concentration of phycocyanin compared to Site 2. Fractionated chlorophyll a showed monthly variations at Site 1 with alternations in the dominance between the two larger fractions. The maximum of the 0.2–2 μm fraction was observed in October but it contributed less to the total chlorophyll a content than nano- or microphytoplankton. Its contribution was higher at Site 2, reaching occasionally ~ 40% of the bulk chlorophyll a. However, nanophytoplankton was the fraction found to respond faster when disturbances occurred. At Site 1, phycocyanin correlated well with total chlorophyll a as well as with the micro- and nanophytoplankton fractions, indicating that cyanobacteria represent an important component of the large-sized phytoplankton in Lake Pamvotis.

Zmiany masy i objętości bulw ziemniaka w wyniku absorpcji wody

Sobol Z.

Inżynieria Rolnicza

2006

R. 10, nr 11(86)

437-445

W pracy wykonano ocenę dynamiki zmian masy i objętości bulw ziemniaka w wyniku absorpcji wody. Do badań przyjęto cztery odmiany ziemniaka tj. Drop, Ibis, Irga i Salto oraz trzy frakcje wielkościowe bulw tj. >60 mm, 50-60 mm i 40-50 mm. Badania wykonano na bulwach nie obranych i obranych po ośmiomiesięcznym okresie przechowywania. Czas absorpcji wynosił 3,5 h, a częstotliwość pomiaru 0,5 h. Przyrost masy bulw obranych w ciągu 3,5 h absorpcji wody wyniósł średnio około 9%, a przyrost objętości ponad 10,5%. Zmiany masy i objętości bulw nie obranych nie przekraczały 0,5%. Wykazano istotną zmianę absorpcji wody przez bulwy dla badanych odmian i frakcji wielkościowych. Przebieg zmian przyrostu masy i objętości od czasu absorpcji wyrażono równaniami nieliniowymi przy pomocy estymacji metodą najmniejszych kwadratów.

The work shows analysis of change dynamics for potato tuber weight and volume due to water absorption. Four potato varieties were used in tests: Drop, Ibis, Irga and Salto, and three tuber size fractions: >60 mm, 50-60 mm and 40-50 mm. The tests were carried out for unpeeled and peeled tubers after eight months of storage. Absorption time was 3.5 h, and measurement frequency: 0.5 h. At the average, peeled tuber weight gain after 3.5 h of water absorption was approximately 9%, and volume gain exceeded 10.5%. Changes in unpeeled tuber weight and volume did not exceed 0.5%. The analysis proved significant change in water absorption by tubers for tested varieties and size fractions. The relation between changes in weight and volume gain and absorption time was expressed by non-linear equations using the least squares method estimation.