The Response of Hydrophytes to Environmental Pollution with Heavy Metals

The effects of Cu²⁺, Cd²⁺, and Ni²⁺ at low and high concentrations (0.025 and 0.25 mg/ml) on the accumulation capacity, the state of the pigment complex, and photosynthesis rate have been studied in model experiments with three floating hydrophytes (Hydrocharis morsus-ranae L., Lemna gibba L., and Potamogeton natans L.) and four submerged hydrophytes (Elodea canadensis Michx., Lemna trisulka L., Ceratophyllum demersum L., and Potamogeton lucens L.). Copper and cadmium are especially toxic at the concentrations studied. The effect of Cu²⁺ was the strongest in hydatophytes, and the effect of Cd²⁺, in pleustophytes. It is hypothesized that the differences between hydrophytes with respect to accumulation of metals and decrease in photosynthesis rate may cause predominant elimination of submerged species. Therefore, changes in the species structure of hydrophyte communities may be expected in waters polluted with metals.     

Influence of exogenous urea on photosynthetic pigments, 14CO2 uptake, and urease activity in Elodea densa—environmental implications

This paper analyzes the effect of exogenous urea in increased concentration gradient (0, 100, 500 and 1,000 mg L^?1) on photosynthetic pigments (measured spectrophotometrically), uptake of ¹⁴CO₂ (using radioisotope), and urease activity (by measuring ammonia with Nessler’s reagent) in leaves of Elodea densa Planch. We have observed that low concentration of urea (100 mg L^?1) stimulates the accumulation of photosynthetic pigments and intensifies photosynthesis in E. densa, whereas high concentration (1,000 mg L^?1) suppresses these processes. Urease activity increased by approximately 2.7 and 8 fold when exogenous urea concentrations were 100 and 500 mg L^?1, respectively. However, exogenous urea in high concentration (1,000 mg L^?1) decreased urease activity by 1.5 fold compared to the control. The necessity of mitigating urea and other nitrogen-containing compounds (NH₃ from urea) in water bodies has been discussed with emphasis on the potential for phytoremediation of urea using common water weed viz. E. densa.     

Experimental Study on the Effects of Population Density of Bloodsucking Mosquito (Aedes communis Deg.) Larvae on Their Biological Characteristics

Results of laboratory experiments on the effects of population density of Aedes communis Deg. larvae on their growth, survival, and sex ratio are presented. At the highest density, larval mortality increased by factors of 1.5 and 2.2, the duration of preimaginal development increased significantly, and the weight of pupae was 11 and 14.7% smaller than in low-density populations. The sex ratio was the same in both cases. The absolute numbers and the biomass of insects per cultivation vessel were greater in high-density populations.     

Dynamics of the composition of the fauna of mosquitoes (Diptera,Culicidae) in parks of Yekaterinburg

The species composition, some zoogeographical parameters, the seasonal dynamics of species diversity, and alternation of active dominant species of bloodsucking mosquitoes have been compared in two green zones of Yekaterinburg, Russia, differing in size and origin: the Southwestern Park Forest and the 50th Anniversary of Komsomol Park. Changes in the abundance and occurrence frequency of mosquitoes during two consecutive years have been studied in the park forest. Phenological parameters of mosquitoes in the natural and artificial green zones of the megalopolis are considered in connection with other parameters of biology and distribution of species.     

Effects of copper(II) ions and copper oxide nanoparticles on <Emphasis Type="Italic">Elodea densa</Emphasis> Planch.

Effects of copper ions and copper oxide nanoparticles on lipid peroxidation rate, activities of anti-oxidant enzymes (superoxide dismutase, catalase, and peroxidase), and photosynthesis have been studied in experiments with Elodea densa Planch. The results show that nanoparticles are more actively accumulated by plants. Both copper ions and nanoparticles activate lipid peroxidation (to 120 and 180% of the control level, respectively). Catalase and superoxide dismutase activities in plants treated with nanoparticles increase by a factor of 1.5–2.0. Copper ions suppress photosynthesis at a concentration of 0.5 mg/l, whereas nanoparticles produce such an effect only at 1.0 mg/l. The observed effects of different forms of copper on E. densa are discussed in a comparative aspect.     

Factors of Carbon and Nitrogen Contents in the Fine Roots of Plants in the Middle Urals

Russian Journal of Ecology - Abstract—Some factors influencing C and N contents in fine plant roots were studied in the Middle Urals. They included ecological (edaphic) features of habitats;...