Е. А. Пасичная, Л. О. Горбатюк, М. О. Платонов, О. О. Годлевська

Институт гидробиологии НАН Украины

ФОТОСИНТЕЗ И ДЫХАНИЕ NAJAS GUADALUPENSIS (SPRENG.) MAGNUS ПРИ КОМБИНИРОВАННОМ ВОЗДЕЙСТВИИ ИОНОВ МЕДИ (II) И МАРГАНЦА (II) ВОДНОЙ СРЕДЫ

Установлены закономерности отдельного и совместного влияния ионов меди (ІІ) и марганца (ІІ) в концентрациях, которые соответствуют их уровням в природных водах, на фотосинтез и дыхание погруженных макрофитов Najas guadalupensis (Spreng.) Magnus. Показано уменьшение токсического воздействия смеси ионов меди и марганца в концентрации 2–5 мкг/дм3 Cu2+ и 20–50 мкг/дм3 Mn2+ на газообменные процессы Najas guadalupensis по сравнению с влиянием отдельных ионов металлов вследствие их антагонизма при аккумуляции растениями. При комбинированном воздействии значительных концентраций ионов меди и марганца (10–20 мкг/дм3 Cu2+ і 100–200 мкг/дм3 Mn2+) увеличивается их токсичность для фотосинтеза и дыхания Najas guadalupensis, что обусловлено накоплением значительного количества металлов в растениях. Высокая чувствительность газообменных процессов Najas guadalupensis к влиянию Cu2+ і Mn2+ дает возможность рекомендовать применение данного вида макрофитов как тест-объекта, а фотосинтез и дыхание – как тест-функций при биотестировании вод, загрязненных тяжелыми металлами.

Ключевые слова: погруженные макрофиты, водная среда, медь, марганець, фотосинтез, дыхание, аккумуляция

O. O. Pasichna, L. O. Gorbatyuk, M. O. Platonov, O. O. Godlevska

Institute of Hidrobiology of NAS of Ukraine

PHOTOSYNTHESIS AND RESPIRATION OF NAJAS GUADALUPENSIS (SPRENG.) MAGNUS UNDER COMBINED INFLUENCE OF COPPER (ІІ) AND MANGANESE (ІІ) IONS OF THE AQUATIC

The regularities of the separate and combined influence of copper (II) and manganese (II) ions at concentrations that correspond to their levels in natural habitats on photosynthesis and respiration of the submersed macrophyte Najas guadalupensis (Spreng.) Magnus have been established. In the study of combined influence of copper and manganese ions on Najas guadalupensis these ions were added to the aquatic environment in such combinations of their concentrations: 0,5 μg/dm3 Cu2+ + 5 μg/dm3 Mn2+; 2 μg/dm3 Cu2+ + 20 μg/dm3 Mn2+; 5 μg/dm3 Cu2+ + 50 μg/dm3 Mn2+; 10 μg/dm3 Cu2+ + 100 μg/dm3 Mn2+; 20 μg/dm3 Cu2+ + 200 μg/dm3 Mn2+. The analysis of the impact of copper and manganese ions on gas exchange functions of Najas guadalupensis has demonstrated that both individual and combined additions of 0.5 μg/dm3 Cu2+and 5 μg/dm3 Mn2+ in 14 days of experiment leads to the increased intensity of photosynthesis of Najas guadalupensis compared with the control data. In this case, under the action of 0,5 μg/dm3 Cu2+ + 5 μg/dm3 Mn2+ the intensity of photosynthesis of Najas guadalupensis has increased by 55.7% as compared with the control. Such an increase is more pronounced than at the individual exposure of 0,5 μg/dm3 Cu2+ (23.9% compared with the control) and 5 μg/dm3 Mn2+ (15.5%) and due to the increase of accumulation of copper and manganese ions from their mixture. It is obvious that with small amounts of these metals in the water environment their absorption by Najas guadalupensis is conditioned by the fact that Cu2+ and Mn2+ are necessary for the plants to function properly. Reduction of toxic impact of Cu2+ and Mn2+ mixture in concentrations 2-5 μg/dm3 Cu2+ and 20-50 μg/dm3 Mn2+ on gas exchange functions of Najas guadalupensis as compared to the effect of their individual ions in these concentrations is showed. It is caused by antagonism of copper and manganese ions in the process of their accumulation by the plants that may be associated with similar radius size of divalent forms of copper and manganese ions. It further leads to competitive activity of ions when they are accumulated by plants. It was established that the combined effect of certain concentrations of copper and manganese ions (10-20 μg/dm3 Cu2+ and 100-200 μg/dm3 Mn2+) leads tо an increase of their toxic impact to photosynthesis and respiration of Najas guadalupensis. In this case, the combined addition of copper and manganese ions to the aquatic environment also leads to a significant increase of their accumulation by Najas guadalupensis, perhaps due to the disruption in the cellular ions transport because of damage in the structure of cell membranes caused by long-term effect of high concentrations of Cu2+ and Mn2+. Thus, with combined addition of the ions in the above mentioned concentrations, the amount of copper in Najas guadalupensis reaches 49-81 μg Cu / (g of dry weight) and that of manganese – 958-1500 μg Mn / (g of dry weight). The intensity of photosynthesis of Najas guadalupensis decreases when the concentration of Cu2+ in water environment is 2-20 μg/dm3 and Mn2+– 100-200 μg/dm3, as well as under the combined influence of the ions in concentrations of 5 μg/dm3 Cu2+ + 50 μg/dm3 Mn2+, 10 μg/dm3 Cu2+ + 100 μg/dm3 Mn2+ and 20 μg/dm3 Cu2+ + 200 μg/dm3 Mn2+. The intensity of respiration of Najas guadalupensis decreases significantly as a result of individual action 10-20 μg/dm3 Cu2+ and 200 μg/dm3 Mn2+ and under the joint influence of 10 μg/dm3 Cu2+ + 100 μg/dm3 Mn2+ and 20 μg/dm3 Cu2+ + 200 μg/dm3 Mn2+. Thus, the results of the research demonstrate that the intensity of photosynthesis of Najas guadalupensis gets reduced at lower concentrations of copper and manganese ions in the water environment in comparison to the intensity of respiration. Individual action of 2-5 μg/dm3 Cu2+ and combined influence of 5 μg/dm3 Cu2+ + 50 μg/dm3 Mn2+ leads to the decrease of the intensity of photosynthesis of Najas guadalupensis together with the activation of respiration – adaptive process aimed at normalizing energy supply of plant organism. The high sensitivity of gas exchange processes of Najas guadalupensis to the influence of Cu2+and Mn2+ makes it possible to recommend the use of this species as an object for testing and photosynthesis and respiration for biotesting of water contaminated with heavy metals.

Keywords: submersed macrophytes, aquatic environment, habitat, copper, manganese, photosynthesis, respiration, accumulation