Ecosystem Chain Research Articles

Ways of migration of ecotoxicants in agro-ecosystems

The fundamental property of ecosystems is the ability to accumulate and contain substances that come to them. The study of problems, in particular the impact of ecotoxicants on agroecosystems, is extremely important for understanding the environmental hazard for the environment biota and humans. Purpose of the research is to consider ways of migrating ecotoxicants with agroecosystems and to offer a unified model of their movement, which can be used to develop measures for preventing or minimizing negative environmental impacts. Paper presents the scheme of ecotoxicants migration by agroecosystems. The main attention is paid to the mathematical assessment of the accumulation of ecotoxicants by plants due to the intake of substances by the endocrine and root paths. In addition, in irrigated agriculture, the need to take into account also the share of ecotoxicants that pass into plants from contaminated irrigation water is shown. Migration of ecotoxicants by agro ecosystems is a rather complicated process, which depends on the physical and chemical properties of substances, soil, water, air and biotic factors. The chamber models method can be used to evaluate the migration of ecotoxicants by ecosystem. It is used to describe the migration of substances by chains of ecosystems, which are conventionally divided into boxes, and the transition between boxes is determined by the coefficients of transition. It is assumed that the substance content in each box is uniform, and between them there is a statistical equilibrium, as well as transition factors are constant for chamber models method. The chamber method is a simple and adequate mathematical description of migration processes in ecosystems of varying complexity. The possibility of forecasting the migration capacity of ecotoxicants by agroecosystems is demonstrated on the basis of the use of chamber model using transition coefficients. We suggest the approach, based on the results of experimental research, which provides an opportunity to assess adequately the ecological hazard of ecotoxicants and develop tools for preventing their negative effects.

Надходження і міграція важких металів наземними та водними екосистемами

Introduction. Potential risks of heavy metals releases into the environment from a wide variety of sources pose a threat to the entire biosphere, including humans, since they are considers as a safe ecotoxicants. The problem of complex research the effects of heavy metals influence on the biota of ecosystems and human health, which has certain achievements, and the unification of their migration paths by chains of ecosystems, including trophic ones, has acquired particular urgency. The purpose of the study is to unify the possible ways of heavy metals migration by terrestrial and aquatic ecosystems in order to justify models of forecasting their displacement that can be used to develop measures to prevent and minimize negative environmental impacts. Materials and methods of research. An important complex indicator that can be used to characterize the migration of ecotoxicants, including heavy metals in ecosystems, is the conversion factor. To estimate the migration of these metals by ground and water ecosystems, chamber models method is used in which chains of ecosystems and their links are divided into chambers, the migration of substances between which is determined by the transition coefficients, and the process itself is described by a system of differential equations based on the laws of kinetics of the first order. Results of the research and their discussion. The laws of the migration of toxic substances by chains of ecosystems and their links are paramount importance in ecology. In the grouping of organisms (biocenosis), there are usually several parallel supply chains, between which interconnection is possible, which ensures the integrity and dynamism of the biocenosis. In case of terrestrial ecosystems, in particular agrocenoses, the entry of substances (heavy metals) into plants occurs due to surface adsorption of leaves and stalks, as well as root-system absorption. The biota plays an extremely important role (hydrofauna and hydroflora), when distributing heavy metals in reservoirs. The principle of migration of heavy metals that come from the atmosphere, surface runoff, groundwater, etc. in rivers is both, the number of them, and the physical and chemical properties of these metals and water, the possibility of formation of bottom sediments, etc. Those who got into marine (ocean) ecosystems are airborne relatively evenly distributed among the main components - water and marine biota (plants, animals and microorganisms), and those that got into the river runoff concentrate, first of all, in the places of their drainage on areas of continental felf. Heavy metals migration by ecosystem chains is a rather complicated process, which depends on many factors. These include, in particular, the physical and chemical properties of the substances themselves and of the soil, water, air, etc., the effects of abiotic (temperature, humidity, etc.) and biotic (soil and aquatic microorganisms and other organisms that can accumulate or transform pesticides) factors, the way of substances entering the body , inclusion in metabolism and much more. To evaluate the migration of heavy metals in the ecosystem, the chamber models method can be applied. It is using to describe the migration of substances along the chains of ecosystems and their links, which are divided into cells, and the transition between the cameras is determined by the conversion factor. For chamber models it is assumed that the concentration of matter in each room is uniform, and between them there is a static stable equilibrium, and also there are conversion factors. It is shown that the chamber models is a simple and adequate mathematical way of describing migration processes in ecosystems of varying complexity. It can be used, including for estimation of migration processes of heavy metals in biocenoses. Conclusions. Given the need to reduce the environmental burden on the environment, problem of unification the natural and man-made sources of heavy metals and the study of migration processes of these environmental pollutants in ecosystems is an extremely urgent problem. An algorithm based on the chamber model method based on the determination of the transfer coefficients of these metals between the chamber chains (links) of the ecosystem is offered to predict the migration of heavy metals in ecosystems. The migration situation of heavy metals in each cell using the laws of kinetics of the first order is described system of differential equations. The presented approach, based on the results of experimental (laboratory and field) studies, is possible for an adequate assessment of the hazard of heavy metals and the development of specific measures to reduce their influence on the ecosystem.

Biodiversity Loss by Riverbank Erosion: A Study on the two Char Unions in Bangladesh

This study has explored the biodiversity loss of Lesraganj and Sutalari char unions through field survey, field observation technique and using BBS data. Bank erosion has destroyed the “habitat” of flora and fauna by disturbing the whole ecosystem chain of the study site. Many fruit varieties were available in mainland among which Jam, Amloki, Jalpai, Dalim, Chalta, Sharifa, and Latkan were not seen in the Charland. All types of homestead palm varieties have been lost while only banana is extensively practiced in the Charland. The mainland was rich in herbs and shrubs, but bank erosion has extinct them completely. The char dwellers are not capable to introduce any aesthetic varieties in the char homesteads and no aquatic vegetation could survive. The many mainland timbering yielding varieties are not found in the Charland except Eucalyptus and Babla while the mainland natural medicinal species cannot survive in the newly formed Charland. The mainland common mammalian fauna and birds are not found in the Charland due to the habitat damage. The mainland was rich in reptiles and amphibian species most of which have become very rare in the degraded char environment.

Feeding, development, and growth of juvenile perch perca fluviatilis in mesocosms in the presence of filter-feeding zebra mussel Dreissena polymorpha pallas

6360 specimens/m 2 , and the biomass was 3.73 kg/m 2 (Perova, 2004). At the same time, the maximum abun� dance of zebra mussel in Lake Erie (United States) reached 700000 specimens/m 2 (Primak, 2002). An abrupt increase in the abundance of zebra mussel in water bodies can lead to changes in the trophic chains of ecosystems. Even a lower abundance of zebra mus� sel leads to the poor food supply of zooplankton; to changes in the structural and functional relationships in bacterial, phytoplankton, zooplankton, and benthic communities; and to changes in the food supply for fish and in the fish productivity of the water body. The rapid invasion of the zebra mussel in Europe and the United States stimulated intensive investigations into the potential effect that this organism may have on the resident components of water biotopes (Dgebuadze,