03. Геолого-географічний факультет
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Перегляд 03. Геолого-географічний факультет за Автор "Ahmad, Muna"
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Документ Morphological deformities of benthic foraminiferal tests in response to pollution by heavy metals: implications for pollution monitoring(1998) Yanko-Hombach, Valentyna V.; Ahmad, Muna; Kaminski, Michael; Янко-Хомбах, Валентина Венедиктовна; Янко-Хомбах, Валентина Венедиктівна; Камински, Майкл; Камінскі, МайклLive foraminiferal assemblages were studied along the Mediterranean coast of northern Israel. Two hundred seventeen benthic foraminiferal species were identified, 30% of which (65 species from 20 calcareous families and one agglutinated family) exhibited 11 distinct types of morphological deformities of their tests. These include: wrong coiling, aberrant chamber shape and size, poor development of the last whorl, twisted chamber arrangement, additional chambers, protuberances, multiple apertures, irregular keel, twinning, lateral asymmetry, and lack of sculpture. Morphological deformities are independent of latitude, taxonomic position, mode of life and feeding strategy of foraminifera. In small numbers (up to 1% of total live population) they can occur within the range of natural variability of a given species in given environmental conditions. However, several species display an increase in the proportion of deformed foraminifera in live assemblages that can be caused by low salinity (e.g., for Adelosina cliarensis) or by an increase in concentrations of heavy metals within the sediment. For example, an increase in deformed Amphistegina lobifera indicates an increase in Cd, Cibicides advenum - Cr, Pseudotriloculina subgranulata - Ti concentrations in sediments. The highest concentrations of Cd are attributed to coarse carbonate substrates adjacent to hard grounds, while Cr and Ti have a strong affinity to muddy- clay substrates enriched with organic matter. Test deformities of benthic foraminifera appear to be sensitive in situ monitors of marine pollution by heavy metals. However, the biochemical and crystallographic mechanisms controlling the development of test deformities remain to be studied by culture experiments under controlled conditions.