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1

Development of toxin-producing cyanobacteria during the water level manipulation in a shallow heavily modified lake

Solis M., Pawlik-Skowrońska B., Kalinowska R.

Oceanological and Hydrobiological Studies

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2015

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Vol. 44, No. 2

223--235

EN

The development of cyanobacteria and microcystin variation was studied during two years in response to periodical water-level regulation in modified Lake Tomaszne. Before the water entrance from a canal, the biomass of toxigenic cyanobacteria was 0.001-0.33 mg dm-3, the microcystin concentration was below 1 μg dm-3, and three variants of microcystins were detected. After the water entrance from the canal, the biomass of cyanobacteria increased to 1.3-7.1 mg dm-3 with the dominants Aphanizomenon gracile and Dolichospermum planctonicum. After the water discharge from the lake, Planktothrix agardhii reached the highest biomass (2.3-6.6 mg dm-3). During the mass development of toxigenic cyanobacteria, the total microcystin concentrations were mostly higher than 5 μg dm-3 and the number of MC variants increased. Both Pl. agardhii and D. planktonicum accounted for microcystin production. The higher NH4-N concentrations supplied with water from the canal supported the biomass increase of Nostocales, whereas Pl. agardhii mass development was due to the low light intensity and high TP concentrations. Our study revealed that the use of nutrient-rich waters for the water management in the hydromorphologically modified lake supported the persistent development of cyanobacteria species leading to increased amounts of MC and a higher number of their structural variants

2

Simultaneous accumulation of anatoxin-a and microcystins in three fish species indigenous to lakes affected by cyanobacterial blooms

Pawlik-Skowrońska B., Toporowska M., Rechulicz J.

Oceanological and Hydrobiological Studies

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2012

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Vol. 41, No. 4

53-65

EN

A four-year study carried out in a lake with perennial water blooms caused by toxigenic Planktothrix agardhii (Oscillatoriales) and Anabaena lemmermanii, Anabaena flos-aquae, Anabaena spp. and Aphanizomenon issatchenkoi (Nostocales) revealed that the lake-dwelling fish were threatened by simultaneous exposure to intracellular and extracellular microcystins (MCs) as well as anatoxin-a (ANTX). Higher contents of anatoxin-a and microcystins were found in livers than in fish muscles. This is the first report on ANTX accumulation in the common fish, indigenous to European freshwaters during perennial cyanobacterial blooms. Generally, the omnivorous roach (Rutilus rutilus) and Prussian carp (Carassius gibelio) accumulated higher amounts of MCs in their tissues compared to mostly predacious perch (Perca fluviatilis), and similar amounts of ANTX. The long-lasting presence of MCs exceeding the safe levels for consumption was found in fish muscles. ANTX accumulation in fish muscles (up to 30 ng g-1 FW) suggests the probability of its transfer in a food chain.

3

Blooms of toxin-producing Cyanobacteria - a real threat in small dam reservoirs at the beginning of their operation

Pawlik-Skowrońska B., Toporowska M.

Oceanological and Hydrobiological Studies

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2011

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Vol. 40, No.4

30-37

EN

Large and harmful cyanobacterial blooms appeared in two newly-built artificial reservoirs shortly after being filled with water. Taxonomic composition of cyanobacterial communities was highly variable in both water bodies and fast species replacement was observed. In the first year of the operation of the smaller Konstantynów Reservoir, the mass development of Anabaena flos-aquae and Planktolyngbya limnetica (48.7 and 53.6% of the cyanobacterial abundance) occurred in summer, while in autumn the dominance of Planktothrix agardhii (99.9%, 14.95 × 106 ind. dm-3 ) was noted. The surface scum developed in summer consisted of An. flos-aquae that contained high amounts of anatoxin-a (1412.4 μg AN-a dm-3 of scum) and smaller amounts of microcystins (10 μg eq. MC-LR dm-3 of scum). In the larger Kraśnik Reservoir, Aphanizomenon flos-aquae occurred in high abundance in spring and summer, however, it was replaced created thick surface scum. Simultaneously, a hazardous increase in the total concentration of microcystins (from 13.6 to 788.5 μg eq. MC-LR dm-3 of water with scum) and anatoxin-a (from 0.03 to 43.6 μg dm-3) was observed.

4

Winter versus summer blooming of phytoplankton in a shallow lake: effect of hypertrophic conditions

Toporowska M., Pawlik-Skowrońska B., Krupa D., Kornijów R.

Polish Journal of Ecology

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2010

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Vol. 58, nr 1

3-12

EN

The comparison of species richness, abundance and diversity of phytoplankton blooms, which developed both in winter and summer seasons as an effect of lake hypertrophy, was the aim of this study. In the ice-covered lake (0.30 mg PO[4]-P L[^-1], 1.35 mg NH[4]-N L[^-1]; TSI[SD] = 64; TSI[chl] = 93), the algal bloom, responsible for high concentration of dissolved oxygen in water, consisted mainly of the centric diatom Stephanodiscus minutulus (3.9 x 10[^7] ind. L[^-1]) accompanied by Limnothrix redekei (Cyanobacteria), Koliella longiseta (Chlorophyceae), > 1.1 x 10[^6] ind. L[^-1] each, as well as Mallomonas sp. (Chrysophyceae) and Monoraphidium komarkovae (Chlorophyceae), >5.0 x 10[^5] ind. L[^-1] each. The toxic cyanobacterium Planktothrix agardhii of extremely long trichomes (up to 0.93 mm) and potentially toxic dinoflagellate Peridinium aciculiferum f. inerme occurred also in high numbers (1.9 x 10[^5] ind. L[^-1] and 7.7 x 10[^4] ind. L[^-1], respectively). In summer (0.05 mg PO[4]-P L[^-1]; 0.42 mg NH[4]-N L[^-1]; TSI[SD] = 78; TSI[chl] = 102), the phytoplankton bloom consisted of P. agardhii (average total abundance 49.4 x 10[^6] ind. L[^-1]) and ten other taxa of Cyanobacteria, Bacillariophyceae, Chlorophyceae and Cryptophyceae (average total abundance 17.9 x 10[^6] ind. L[^-1]). The total phytoplankton abundance was 1.5 times higher in summer than in winter and the total biomass of the most abundant species was approximately 4 times higher in warm (139.8 mg L[^-1]) than in cold season (32.5 mg L[^-1]). The values of the Shannon-Weaver diversity index were very low, however, over 2 times higher in summer (0.60) than in winter (0.31). The obtained results revealed that in the hypertrophic lake the very high nutrient concentrations (especially NH[4]-N and PO[4]-P), found both in winter and summer, were responsible for year-long mass development of phytoplankton. The winter phytoplankton was composed mainly of very small centric diatoms, whereas summer blooms were created by filamentous cyanobacteria (mainly Oscillatoriales; 98%).

5

Sedimentary imprint of cyanobacterial blooms : a new tool for insight into recent history of lakes

Pawlik-Skowrońska B., Kornijów R., Pirszel J.

Polish Journal of Ecology

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2010

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Vol. 58, nr 4

663-670

EN

Recent history of numerous lakes is, among others, a consequence of anthropogenic activity that led to water eutrophication and excessive phytoplankton development. In nutrient-rich lakes both biomass of cyanobacteria and cyanotoxins, that may have a substantial impact on aquatic biocenoses, are present not only in water column but also in the bottom sediments. This study demonstrates vertical distribution of microcystins (MC) traces in sediments of two eutrophic lakes - one phytoplankton/macrophyte-dominated and the other phytoplankton-dominated. The sediments (1-40/50 cm depth) were sampled from central part of lakes and content of MC traces was determined by means of GC-MS in 1cm core slices. In the sediment profile (1-40 cm depth) of the phytoplankton/macrophyte-dominated lake the MC contents ranged from 0.011 in deep layer (35 cm) to 0.910 [mu]g equival. MC-LR g[^-1] d.w. in the surface layer (1 cm) and indicated gradual increase in eutrophication . connected with mass development of cyanobacteria over time. In phytoplanktondominated lake, MC contents (0.0-0.335 [mu]g equival. MC-LR g[^-1] d.w.) oscillated through the core (1-50 cm depth) and were relatively similar in older, deeper (20-50 cm) and younger (1-20 cm) layers what suggests long-lasting but variable intensity of cyanobacteria mass development. The obtained results indicate that traces of microcystins persist and are detectable for several dozens years not only in surface but also in deep sediment layers of lakes affected by former cyanobacterial blooms. They seem to be a reliable tool to follow eutrophication and its consequence - excessive development of cyanobacteria in the past time.

6

Metal resistance of soil algae (Chlorophyta) occurring in post-flotation Zn/Pb and Cu-tailing ponds

Kalinowska R., Pawlik-Skowrońska B.

Polish Journal of Ecology

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2008

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Vol. 56, nr 3

415-430

EN

Algae as pioneer organisms are important in extreme environments. We isolated several green algae (Chlorophyta) from Zn/Pb- and Cu-enriched ground samples of post-flotation tailing ponds, containing 17200-18400 mg Zn kg[^-1], 3017-6566 mg Pb kg[^-1] or 1420 mg Cu kg[^-1]. The algae with different morphologies belonged to following classes: Chlorophyceae and Trebouxiophyceae. Their Zn-, Pb- and Cu- resistance in comparison with soil green algae (Chlorophyceae) isolated from the unpolluted control soil was evaluated under laboratory conditions on the basis of 96h-EC[50] (effective metal concentration which causes 50% inhibition of algal growth after 96 h exposure). Among isolated algae Dictyococcus cf. varians Gerneck em. Starr from the Zn/Pb-tailing pond was highly resistant both to lead (EC[50] 48 [my]M) and zinc (EC[50] 126 [my]M), but sensitive to copper (EC[50] 2 [my]M). Stichococcus minor Nageli and Chlamydomonas boldii Ettl from the Cu-tailing pond were resistant to copper (EC[50] 17.8 [my]M and 10 [my]M, respectively). Simultaneously, S. minor revealed co-resistance to Zn (EC[50] 251 [my]M), while C. boldii to Pb (EC[50] 38.9 [my]M). Geminella terricola J.B. Petersen (Chlorophyceae), isolated from the unpolluted control soil, revealed high sensitivity to the three metals (Zn-EC[50] 44.6 [my]M; Pb-EC[50] 10.2 [my]M and Cu-EC[50] 6.4 [my]M). Simultaneously, G. terricola accumulated intracellularly higher amounts of Zn (7.1 amol [my]m[^-3]) and Cu (5.5 amol [my]m[^-3]) than all the algae from the polluted ground samples (Zn: 1.2-6.4 amol [my]m[^-3] and Cu: 0.4-2.7 amol [my]m[^-3]). It also accumulated high amounts of Pb (6.0 amol [my]m[^-3]), but two-fold lower than D. cf. varians. Using cytochemical staining of metals dark pink Pb-rhodizonate complexes were detected in thick cell walls of the Pb/Zn-resistant D. cf. varians and in thick mucilage layers of the Cu/Pb-resistant C. boldii. However, in the Pb-sensitive S. minor Pb-complexes were detected inside deformed cells. Pink-orange Zn-dithizone complexes were mainly distributed inside the cells of the Zn-resistant D. cf. varians. The results obtained suggest that thick cell walls or envelopes may be partly responsible for the higher Pb-resistance of some studied algae. However, in the case of micro-nutrients like Zn or Cu other resistance mechanisms (biochemical / physiological) may be involved. It seems that algal species or ecotypes living in the grounds of metal post-flotation tailing ponds have been adapted to heavy metals present in their habitats and may be useful for remediation of such degraded environments.

7

Heavy metal accumulation, resistance and Physiological status of some epigeic and epiphytic lichens inhabiting Zn and Pb polluted areas

Pawlik-Skowrońska B., Wójciak H., Skowroński T.

Polish Journal of Ecology

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2008

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Vol. 56, nr 2

195-207

EN

Heavy metal accumulation, physiological status and resistance against Zn and Pb were compared in lichens occurring in metalpolluted (Silesian Upland, S. Poland) and unpolluted (forest complex, NE Poland) areas. Sandy soil near Zn/Pb ore mine had significantly lower (5.35-times) metal content than dolomite-containing ground of mine tailing dump in polluted area (S. Poland). Metal contents in native lichens sampled from those sites followed the same pattern. Total Zn, Pb, Cd and Cu contents in native lichens recorded in two sites of Zn/Pb mining area varied broadly and were considerably higher than in lichens from a control unpolluted site. Independently of the sampling site, epiphytic lichens of higher surface to biovolume ratio (i.e. Candelariella Mull. Arg., Lepraria Ach.) accumulated much more metals (6.05 - 9.57 mg g[^-1] DW) than lichens of a lower ratio (e.g. 0.25 mg g[^-1]DW in Peltigera didactyla (With.) J.R.Laundon or 0.29 mg g[^-1] DW in some Cladonia Hill ex Browne). In general, the studied lichens accumulated metals in the following order: Zn>Pb>Cd=Cu, that was in agreement with the metal content in soils. However, Cladonia furcata (Huds.) Schrad. from tailing dump contained 2-fold more Pb than Zn. Internal Zn and Pb contents (non-exchangeable fraction) in the studied lichens ranged broadly from 17 to 90% of the total metal content. Phaeophytinisation quotients (PhQ), total chlorophyll contents and chl a/b ratios in the native lichens from polluted sites ranged 0.84 - 1.44; 0.514 - 4.858 mg g[^-1] DW and 2.09 - 5.56, respectively. Experimental exposure of selected species (Hypogymnia physodes (L.) Nyl., Hypocenomyce scalaris (Ach.) Choisy, Lepraria elobata Tonsberg, L. incana (L.) Ach., sampled from the both polluted and unpolluted sites, to high doses of Zn[^2+] and Pb[^2+] (0.36 or 0.72 mmol g[^-1] DW) revealed higher resistance of lichens from the Zn/Pb-polluted sites than con-specific lichens from the unpolluted one. The resistance of epiphytic species from the polluted area to high doses of Zn[^2+] and Pb[^2+] increased as follows: H. physodes

8

Replacement of chroococcales and nostocales by oscillatoriales caused a significant increase in microcystin concentrations in a dam reservoir

Grabowska M., Pawlik-Skowrońska B.

Oceanological and Hydrobiological Studies

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2008

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Vol. 37, No.4

23-33

EN

A two-year study on cyanobacterial development and the dynamics of intracellular microcystins was carried out in a shallow dam reservoir. Potentially toxic cyanobacteria (Microcystis wesenbergii, M. aeruginosa, Woronichinia naegeliana, Anabaena spp., Planktothrix agardhii) were observed to be the main component (70-94% total biomass) of the phytoplankton community, in which species composition was unstable and was very different between the 2005 and 2006 summer seasons. Generally, total phytoplankton, cyanobacterial biomass and total microcystin (MC) concentrations in the reservoir were much higher in 2006 than in 2005. The highest MC concentration (173.8 žg MC-LR equivalent dm-3) was seen in 2006 during P. agardhii (Oscillatoriales) domination (max. fresh biomass 50.3 mg dm-3; above 91% of phytoplankton biomass). Positive correlations between microcystin concentrations and cyanobacterial biomass suggest that populations of Nostocales and Oscillatoriales in 2005 and Oscillatoriales (P. agardhii) in 2006 may have been the main producers of MCs in the reservoir. The strong increase in P. agardhii biomass concomitant with a decrease in the total biomass of Chroococcales and Nostocales was responsible for the increase in MC concentration in the Siemianówka dam reservoir.

9

Epiphytic algae on Stratiotes aloides L., Potamogeton lucens L., Ceratophyllum demersum L. and Chara spp. in a macrophyte-dominated lake

Toporowska M., Pawlik-Skowrońska B., Wojtal A.Z.

Oceanological and Hydrobiological Studies

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2008

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Vol. 37, No.2

51-63

EN

Epiphytic algae occurring on submerged macrophytes were investigated as part of a study on the ecological status of a shallow macrophyte-dominated lake, Lake Skomielno, which has been used for recreation and fishery. Relatively high variability in biomass (DM) and chlorophyll a contents in epiphyton on particular plants was noted. Generally, the biomass of epiphytic algae was much higher in spring and autumn than in summer. In total, 335 taxa were found on the studied macrophytes with representatives of the Chlorophyta (143 taxa) and Heterokontophyta class Bacillariophyceae (131 taxa) dominating. The species composition of epiphytic algae was related to host plant and seasons, the highest species richness was observed on Stratiotes aloides in spring and on Potamogeton lucens in autumn. The Jaccard similarity index revealed differentiation of diatom communities between the macrophytes. Our data suggest that in the studied lake S. aloides and P. lucens can provide better habitat conditions for higher numbers of epiphytic taxa, abundances and epiphyton standing crop than Ceratophyllum demersum and Chara spp. can. The dominance of diatom species (e.g. seudostaurosira brevistriata (Grun.) Williams & Round, Achnanthidium minutissimum (Kütz.) Czarnecki, and Cocconeis placentula Ehrenb.) that are known as bioindicators of slightly alkaline, sufficiently oxygen-saturated and meso-eutrophic waters corresponds well with the physico-chemical parameters of Lake Skomielno.

10

Relationship between Cyanobacterial bloom composition and anatoxin-a and microcystin occurrence in the eutrophic dam reservoir (SE Poland)

Pawlik-Skowrońska B., Skowroński T., Pirszel J., Adamczyk A.

Polish Journal of Ecology

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2004

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Vol. 52, nr 4

479-490

EN

Long-lasting cyanobacterial blooms were observed over summer periods 2001-2003 in the highly eutrophic dam reservoir (Zemborzycki Reservoir near Lublin, SE Poland) loaded with nitrogen and phosphorus by the river Bystrzyca. Chloriphyll a content and water transparence reached in summer periods 2002-2003 average values 115-129 [mi]g l^-1 and 0.5 m, respectively. The blooms consisted of eight taxa of Cyanobacteria occurring in different proportions: Aphanizomenon flos-aquae, Anabaena circinalis, Anabaena spiroides, Anabaena flos-aquae, Planktothrix agardhii, Microcystis aeruginosa, Microcystis viridis, Microcystis wesenbergii. At decreased average water temperature and increased concentration of dissolved ammonium-nitrogen in summer 2003, compared with two earlier years, a replacement of dominant Aph. flos-aquae to P. agardhii was observed. The total abundance of potential microcystin producers was positively correlated with the content of these hepatotoxins in the reservoir water. First time in Poland, mass occurrence of Anabaena strains producing anatoxin-a was observed. Anatoxin-a concentration in the reservoir water was positively correlated with total abundance of 3 taxa of Anabaena. It was no such correlation with Aph. flos-aquae.

11

Biosorpcja i usuwanie Cd, Cu, |Pb oraz Zn z roztworów wodnych przez sorbenty uzyskane z grzyba pleśniowego Rhizopus nigricans i odpadowej biomasy drożdży Saccharomyces uvarum

Pawlik-Skowrońska B., Pirszel J., Skowroński T.

Archiwum Ochrony Środowiska

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2000

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Vol. 26, no. 1

39--53

PL

Badano i porównywano pojemność kationowymienną oaz sorpcję Cd, Cu, Pb i Zn przez biosorbenty uzyskane z grzyba pleśniowego Rhizopus nigricans oraz odpadowej biomasy drożdży z przemysłu fermentacyjnego Sccharomyces uvarum. Pojemność kationowymienną biomas grzybowych wyznaczano metodą miareczkowania potencjometrycznego, natomiast sorpcję metali ciężkich badano przy użyciu metody radiometrycznej (Cd i Zn) oraz atomowej spektroskopii absorpcyjnej (Cu i Pb). Stwierdzono, że sorbent z R. nigricans charakteryzuje się ok. 2,5-krotnie większą pojemnością kationowymienną (633 ueq/g s.m.) niż sorbent z S. Uvarum (247 ueq/g s.m.) wiąże proporcjonalnie większe ilości badanych metali (0,51 mmola Pb/g s.m. ; 0,27 mmola Zn/g s.m.; 0,23 mmola Cu/g s.m. ; 0,19 mmola Cd/g s.m.) oraz ma lepsze właściwości mechaniczne. Wielkość sorpcji Cd, Cu, Pb i Zn była zależna od Ph roztworu metali. Sorpcja Cd i Zn na obu sorbentach wzrastała wraz ze wzrostem pH w zakresie 4 - 7, sorpcja Pb osiągała podobne maksymalne wartości w zakresie pH 5 - 7, a zmniejszała się o ok. 50% przy pH 4, natomiast sorpcja Cu osiągała najwyższe wartości w zakresie pH 6 - 7. Stwierdzono, że ok. 17-krotny nadmiar kationów Ca(2+) i Mg(2+) powodował nieznaczne zmniejszenie sorpcji Cd, Cu i ZXn przez oba sorbenty, natomiast obniżał sorpcję Pb przez S. uvarum (o 25%). Obecność ortofosforanów nie powodowała zmian w wielkości sorpcji Cd, Cu i Zn, natomiast chlorki wpływały na obniżenie o 26% sorpcji kadmu przez badane sorbenty. Jednoczesna obecność obu tych ligandów nieorganicznych niwelowała do pewnego stopnia hamujący wpływ chlorków. Sorbent z R. nigricans zastosowany jako złoże w kolumnie efektywnie usuwał kadm z roztworu o stężeniu 1 mM Cd.

EN

The cation-exchange capacity and biosorption of Cd, Cu, Pb and Zn by sorbents prepared from mould fungus Rhizopus nigricans and waste yeast bomas of Saccharomyces uvarum were determined and compared. The cation-exchange capacities of fungal biomasses, were determined by means of potentiometric titration. Heavy metal sorption was measured using both radiometric method (Cd, Zn) and ASA (Pb, Cu). It was found that the biosorbent of R. nigricans possesses ca. 2.5-fold higher cation-exchange capacity (633 ueq/g dry wt.) than the sorbent of S. Uvarum (247 ueq/g dry wt.), can bind proportionally higher amounts of heavy metals )0,51 mmole Pb/g dry wt.; 0,27 mmole Zn/g dry wt.; 0,23 mmole Cu/g dry wt.; 0,19 mmole Cd/g dry wt.) and has better mechanical properties. The sorption of Cd, Cu, Zn and Pb by both fungal sorbents was pH-dependent. Cd and Zm sorption increased with the pH increase within the range 4 - 7. Pb sorption was highest within the pH range 5 - and decreased significantly (by 50%) at pH 4, while Cu sorption was highest within the pH range 6 - 7. The excess of Ca and Mg in heavy metal mixture did not cause any essential decrease of Cd, Cu and Zn sorption, however, the Pb sorption by S.uvarum decreased by 25%. The presence of orthophosphate did not decrease the Cd, Cu and Zn sorption, but chlorides caused a decrease of Cd sorption by 26%. The presence of phosphates in the heavy metal mixture containing chlorides caused higher metal sorption than in solution containing chlorides only. The sorbent of R. nigricans used as a bed in column removed efficiently cadmium from aqueous solution of the concentration 1 mM Cd.

12

The sorption and removal of heavy metals by algal biomasses

Pawlik-Skowrońska B., Pirszel J., Skowroński T.

Oceanological Studies

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1998

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Vol. 27, No. 1

91-103

EN

Metal sorption capacity of Chlorella kessleri and two strains of cyanobacteria (Aphanocapsa sp., Anabaena flos-aquae) was studied. It was found that among studied organisms, dead cells of C. kessleri were the most effective sorbents of Pb, Cu, Cd and Zn. They displayed the highest cation-exchange (Cd2+/H+) capacity and bound much more Cd and Zn at pH 7 than at pH 4. The optimum pH for sorption of Pb and Cu was 6. At pH 6, dead cells of C.kessleri could bind maximally about 37 mg Cd, 38 mg Zn, 21 mg Cu and 70 mg Pb per g of dry weight. Generally, algal dead cells (0.3 g dry wt dm^3) removed 50-70% of the metal ions from 0.01 mM solutions. A surplus of calcium and magnesium caused a slight decrease of Pb, Cu, Cd and Zn sorption.

13

The impact of some organotins on the unicellular cyanobacterium Synechocystis aquatilis

Pawlik-Skowrońska B., Kaczorowska R., Skowroński T.

Oceanological Studies

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1998

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Vol. 27, No. 1

79-90

EN

The impact of some organotin compounds (10-200 mg dm^3) on the planktonic cyanobacterium Synechocystis aquatilis was studied. The following order of toxicity of organotins tested to the cyanobacterium culture was found: DBTCl TPTAclTBTCl? TPTCl TMTCl. Chlorophyll a content in the culture seemed to be more susceptible to organotins than cyanobacterial growth. The inhibition of both parameters increased significantly with the increase of compound doses, time of exposure and decrease of initial culture density. After 96 h exposure, the chlorophyll a content in the cyanobacte-rium cultures of the initial density 56 mg dry wt dm^3 was reduced for 200 mg dm^3 of DBTCl, TBTCl and TPTCl by 70%, 50% and 20% respectively, while in the cultures of the lowest initial density (10 mg dry wt dm-3) by 90%, 75% and 50%, as compared to the organotin free controls.