| Abstract [eng] |
Gediminas Petrėnas Experimental study of cadmium - indicating freshwater diatoms SUMMARY The study is carried out with an understanding of the importance of biological monitoring, biological observation has many advantages, and is considered a valuable tool for both ecological and human health care. The development and application of biological monitoring provide a better knowledge of the effects of chemicals on living organisms, while at the same time ensuring better protection of public health and the environment. Therefore, this study is useful in recognizing the lack of data and indices in terms of water pollution of flints as biological indicators for wider application. The aim is to determine the effect of heavy metal - cadmium on fitoperiphitonic diatoms, assessing the tolerance and somatic changes of their different species. During the main activity study: 1) to grow colonies of diatoms in a selected, natural place of the river and transfer them to experimental containers prepared in the laboratory, 2) an experiment in containers with different concentrations of cadmium is carried out for six weeks, observing changes and deformations in the species composition of diatoms. The main result of the study is the description of the reaction of diatom species to cadmium concentrations in water qualitatively and quantitatively. In the study we found that as cadmium concentrations rise, the diversity of species decreases (r2 = 0.7; p < 0.01). In the cadmium-free control sample, there were 68 species, with a corresponding change in cadmium concentrations reducing the number of species, from 59 species at a cadmium concentration of 0,01 mg/l to 52 at 0,1 mg/l. We found two types of deformations: Frustule deformations and raphe deformations (at a higher cadmium concentration, their frequency increases - 0.1mg/l cadmium deformations 146 times more than in the control sample, and at 0.04mg/l – 111 times and at 0.01mg/l – 71 times more than in the control sample). The most common deformations were shown by diatoms of the genus Navicula. In the experiment, 14 percent of the species were identified that showed a reliable correlation (p<0.05) with cadmium concentrations, so the most susceptible species to cadmium considered to be: Navicula lanceloata (rs = -0.842), Navicula rostellata (rs = -0.699), Craticula acomodata (rs = -0.415), and the most insensitive ones – Achnanthidium sp. (rs = 0.432), Fragilaria sp. (rs = 0.453), Sinedra sp. (rs = 0.496). We have classified these species of diatoms as cadmium-indictments, the regression models drawn up accordingly indicate the abundance of cadmium in contaminated artificial ecosystems. The methodological experience and results of this test will contribute to further research in determining indicator values of diatoms, and it will be possible to apply biological indicators for the control of cadmium pollution from the dischargers of treatment plants. Possible perspective in an environmental protection, application of an environmental pollution control. |
