Man-made plutonium radioisotopes in the salt lakes of the Crimean peninsula

Investigations of ^(239+240)Pu and ^(238)Pu in the surface layer(0–5 cm) of bottom sediment in the Crimean 10 salt lakes from 4 geographical groups were carried out for the first time. The ^(239+240)Pu varied widely between regional geographical groups of lakes as well as within groups too and ranged from 11±4 to 451±43 mBq^(239+240)Pu/kg. The highest levels of ^(239+240)Pu—419±27, 443±24 and 451±43 mBq/kg were observed in the Yevpatoriya(Lake Kyzyl-Yar), the Tarkhankut(Dzharylhach) and the Kerch group(Tobechik), respectively. The lowest values of ^(239+240)Pu were identified in three lakes of the Perekop group and were 20±12, 24±6 and 48±6 mBq/kg. In all lakes ^(238)Pu was an order of magnitude lower than 239+240 Pu and varied from 4.8±2.6 to 30.7±5.5 mBq/kg. The ^(238)Pu activity was decay-corrected to 1986. The characteristic ratio of the ^(238)Pu/239+240 Pu activities in the sediment and percentage of the Chernobyl-derived Pu was calculated. The largest percentages of the Chernobyl-derived Pu were observed in the Evpatoriya group(Lake SasykSivash)—16.2%±8.26%, the Tarkhankut group(Dzharylhach)—8.4%±2.10% and the Kerch group(Aktash)—10.5%±5.56%. The study of the depth distribution of plutonium in the Lake Kyzyl-Yar bottom sediment core(0–25 cm) was fulfilled. It was shown that 239+240 Pu was high enough in all studied layers of bottom sediment, but the highest activity ratio ^(238)Pu/239+240 Pu(0.062±0.020) was found in the deepest layer of 15–20.5 cm and the percentage of Chernobyl-derived Pu was estimated at 6.8%±2.85% in this layer.

The vertical structure of the vegetative canopy of the brown algae Cystoseira(Black Sea)

In the coastal ecosystems of the Black Sea,macrophytobenthos and,in particular,the association of Cystoseira crinite,C.barbara,Cladostephus verticillatus,and Corallina mediterranea,with its thick vegetative canopy(VC),is the key contributor to primary production(PP).Though the vertical structure of the canopy,formed by the algal association,is of principal importance to the PP level,this subject has been long-neglected by researchers.The goal of our work was to compare vertical structures of the vegetative canopy of Cystoseira brown algae under diverse hydrodynamical conditions of the Crimean Peninsula coast.Samples were collected using the 50 cm×50 cm counting frame at eight stations positioned in shallow(55-60 cm deep)sites of Sevastopol Bay(Crimean Peninsula).Dry weight biomass of the VC was determined for all algae assemblage and for each algal species individually,per horizontal surface unit,at each height(Z).The study shows that:1)the VC is characterized by unimodal vertical distribution of biomass,with maximum estimate in the lower part,where the biomass increases to 85%of the total biomass;2)a series of single-peaked curves reliably describes the unimodal distribution of the biomass;thalli of different age groups are found along the canopy profile;and 3)algae found in epiphytic synusia prefer inhabiting the upper part of the VC.The role of environmental factors(seawater turbulence and solar radiation)is discussed in reference to the formation of the vertical structure,made up of the associations of the brown algae Cystoseira.

Neutron Activation Analyses Used to Study Elemental Accumulation in Some Marine Macrophytes (Mediterranean Sea Coast of Egypt)

The concentrations of Na, Mg, Al, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se Br, Rb, Sr, Zr, Mo, Ag, Sb, I, Cs, Ba, La, Sm, Eu, Tb, Yb, Hf, Ta, W, Au, Th and U in 6 types of marine macrophytes (algae and seagrass): Gelidium pusillum (Stackhouse) Le Jolis, Ulva intestinalis Linnaeus, Amphiroa rigida J.V. Lamouroux, Hypnea sp., Cystoseira sp. and Posidonia oceanica (L.) Delile (seagrass) collected from 3 stations along the Mediterranean Sea coast of Egypt were determined using instrumental neutron activation analysis. The contents of elements in marine macrophytes indicated that they accumulated elements at different levels depending on their type of species (brown, red, green and seagrass) and the ambient water conditions. However, the concentrations of Cr, Co, Ni, Se, Zr, Mo, Ag, Cs, La, Sm, Eu, Yb, Hf, Ta, Au and U were very similar in all samples. In general the levels of classically investigated elements, particularly Mn, Fe, Co, Ni and Zn determined in the macrophytes in the present study are lower or within the wide range of values previously reported for species of these genera sampled along the Egyptian Mediterranean coast.

Cladophora mats in a Crimean hypersaline lake:structure,dynamics,and inhabiting animals

Filamentous green algae play an important functional role in element cycling and productivity in the diff erent water bodies. In hypersaline lakes and lagoons of the Crimea, filamentous green algae are present and form bottom and floating mats that occupy large areas with high biomass, up to 4–5 kg(wet biomass)/m2. Cladophora spp. dominated in those mats. Five species of filamentous green algae(Chlorophyta) in Lake Chersonesskoye: C ladophora vadorum(Aresch.) Kütz., C. siwaschensis C. Meyer, C. echinus(Biasol.) Kütz., Ulothrix implexa(Kütz.) Kütz., Rhizoclonium tortuosum(Dillw.) Kütz., and seagrass(Angiospermae) R uppia cirrhosa(Petagna) Grande were found. Cladophora spp. and R. cirrhosa were found in the lake throughout the year, other types of algae were encountered episodically. In most cases the biomass of bottom mat exceeded that of the floating mat. In general, the total biomass of the bottom and floating mats in the lake areas at depths up to 30 cm was in a stable range of values from 100 to 290 mg(dry weight)/cm2. Animal and infusorian average abundance in mats reach high values: infusorians—up to 15 000 000 ind./m2, Cletocamptus retrogressus(Copepoda, Harpacticoida)—up to 730 000 ind./m2, Eucypris mareotica(Ostracoda)—up to 91 000 ind./m2 and Chironomidae larvae(Insecta, Diptera)—up to 140 ind./m2. Those values were much higher than in the plankton.

How can saline and hypersaline lakes contribute to aquaculture development?A review

A considerable part of the world's population is currently experiencing a severe scarcity of freshwater and nutrition. Inland aquaculture has the fastest growth in fresh waters, and this contributes to the eutrophication of freshwater bodies. The increase in freshwater aquaculture impacts on the increasing demand for fresh water. A way to overcome this is to develop aquaculture in saline lakes. This article discusses how saline and hypersaline lakes may contribute to overcome this problem and gives a list of fish and shrimp species that can be cultivated in saline lakes. Successful development of aquaculture depends on a healthy cultured stock of commercial fish and shrimps. A sustainable healthy stock of fish and shrimps can be only maintained using live food for the cultured fish larvae, fry and fingerlings. As well as Artemia spp. there are many other crustacean species with the potential for growing in hypersaline waters. At least 26 copepod species around the world can live at a salinity above 100 g/L with 12 species at a salinity higher than 200 g/L, and these all have excellent nutritional value. There is a high potential to use eukaryotic organisms of diff erent taxa in saline/hypersaline aquaculture for food, agri-aquaculture, diff erent industries and as food supplements.