Оцінка здатності зелених нитчастих водоростей до очистки води від важких металів

Анотація

ASSESSMENT OF ABILITY OF GREEN FILAMENTOUS ALGAE TO WATER PURIFICATION FROM HEAVY METALS

O. O. Pasichna, O. O. Godlevska

The rapid pace of urbanization, industrialization, excessive use of fertilizers and pesticides has led to pollution of land and water resources by heavy metals. Unlike most organic matter, metals cannot be transformed and degraded, so they accumulate in water, soil, bottom sediments and living organisms. Thus, pollution with heavy metals of the environment is a serious problem. In such conditions, there is a need to find efficient, affordable and cheap methods for purification the aquatic environment from excess of heavy metals. Traditionally, physic-chemical and biological methods are used in the treatment of sewage, mainly using active sludge, which does not lead to the achievement of stable residual concentrations of pollutants. In connection with this, for the purification of such waters, different systems are used, using both individual hydrobionts and their groups. Therefore it is necessary to identify those types of hydrophytes common in reservoirs, which have the ability to accumulate a significant amount of metals and also are resistant to metal action, so can be used for water purification from these toxicants.

The aim of this work was to study the accumulation of heavy metals (on the example of ions of copper and manganese) by green filamentous algae, which are common in reservoirs of Ukraine, and also to establish a correlation between the content of metals in plant organisms and their concentration in water in order to identify those species that effectively accumulate the metals from aquatic environment and reduce their concentration in water, thus purifying it.

The objects of our research were green filamentous algae Cladophora glomerata (L.) Kütz. and Oedogonium cardiacum (Hass.) Wittr. For study of accumulation of the metals (copper and manganese ions) by algae, copper (II) ions (CuSO₄×5H₂O) at concentration of 0.5, 2, 5, 10 and 20 mg/dm³ and manganese (II) ions (MnSO₄×5H₂O) - 5, 20, 50, 100 and 200 mg/dm³ were added to the aquatic environment separately and together. Experimental studies were 14 days. Determination of the metals content in algae was carried out using atomic adsorption spectrophotometer. The amount of accumulated metals in algae was calculated in micrograms per 1 g of dry weight.

The results of our investigations indicate on accumulation of large amounts of copper and manganese by green filamentous algae Cladophora glomerata and Oedogonium cardiacum. With increasing concentrations of Cu^{2 +} and Mn^{2 +} in an aquatic environment, there is almost proportional increase the content of both metals in algae.

In general, filamentous algae accumulate more metals than submerged higher aquatic plants, in particular Elodea canadensis Michx. and Ceratophyllum demersum L. It is known that the cellular shells of algae consist mainly of polysaccharides and are not a serious obstacle for the penetration of metals to the membrane. Due to its biochemical composition and high adsorption capacity, a large amount of the metals is accumulated around the membranes, and subsequently - inside the cells. The vacuoles of filamentous algae are large in size and, due to this, fulfill the spatial function and increase the relative assimilation surface of the cells by 4-5 times.

For removing metals from much contaminated water, the aquatic plants species with the ability to accumulate large quantities of metals and significant resistance to their action are recommended, because the rapid death of plant organisms leads to secondary pollution of water. This is especially important for sewage, in which the concentrations of metals ions reach significant values. As a result of our studies, it has been shown that along with the ability to accumulate significant amount of the metals, filamentous algae Cladophora glomerata and Oedogonium cardiacum. are sufficiently resistant to their action, so they can be recommended for removal of metals from aquatic environment with a significant level of contamination, in particular, for the purification of sewage.

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