Dana Komínková

Impact of urban drainage on metal distribution in sediments of urban streams

The concentrations of total and extractable heavy metals (Cu, Zn, Pb, Cd, Cr and Ni) and other sediment properties were determined in sediments of three urban streams in Prague. The mean sediment concentrations (in mg kg(-1) (dry weight)) ranged within 0.2-3.2 (Cd), 20.2-61.7 (Cr), 16.3-135.2 (Cu), 17.8-42.5 (Ni), 20.2-114.8 (Pb) and 79.4-446.3 (Zn). The chemical distribution of metals, determined in four chemical sediment fractions of the sediment, indicates an increase of the distribution of Cu and Zn in more easily available fractions in sediments affected by combined sewer overflows. The highest percentages of Cd and Zn are in the most labile acid-soluble fraction (38-64% and 15-43% respectively), whereas Pb is bound mainly to reducible fraction.

Environmental Impact Assessment and Application – Part 1

Environmental impact assessment (EIA) is one of the main legislative tools established to minimize an anthropogenic impact on the environment. EIA can be defined as “a process by which information about the environmental effects of a project is collected, both by the developer and from other sources, and taken into account by the relevant decision-making body before a decision is given on whether the development should go ahead.” Any EIA consists of three key stages. The first stage (preliminary assessment) involves the identification and collection of relevant information, which is called screening. During this step the decision is made on whether an EIA is required for the project. If an EIA is required, then the second stage starts. The second stage, called scoping identifies what constitutes relevant information to be identified and assessed with respect to key impacts of the proposed development. The results from scoping process are reported to the relevant decision-makers in an ‘environmental impact statement’ (EIS). The final stage comprises the review of the EIS and its adequacy as a basis for the competent/approving authority to make the decision on ‘development conditions’.

Fatty Acids in Anopheline Mosquito Larvae and Their Habitats

ABSTRACT: Larvae of the three important Central American malaria vectors, Anopheles albimanus, An. vestitipennis, and An. darlingi, are found in distinctly different habitats broadly defined by hydrology and aquatic vegetation, but little is known about the actual food quality and quantity of these habitats. Polyunsaturated fatty acids (PUFA) are of special interest, because mosquitoes require 20:5&ohgr;3 (EPA), 20:4&ohgr;6 (ARA), and 22:6&ohgr;3 (DHA) and without an adequate supply of these PUFAs they are not able to complete their life cycle. We collected samples of larvae and their corresponding habitats and analyzed their fatty acid (FA) composition to reveal if there are any species-specific and habitat-specific differences in FA composition, and if habitat FA differences can be linked to differences in the mosquito FA pattern and, ultimately, mosquito performance. We also assessed how FA of wild larvae compare to the laboratory-reared larvae. Habitats were generally low in essential PUFAs and there were no significant differences among the FA composition of habitat samples. There were significant differences in FA composition of larvae. An. darlingi contained significantly higher amounts of FA, specifically a higher content of &ohgr;-6 PUFA, represented mainly by the linoleic acid (18:2&ohgr;-6). Large differences were found between field-collected and laboratory-reared An. vestitipennis larvae, especially in the content of PUFAs. The laboratory-reared larvae contained significantly more of the total FA, &ohgr;3 PUFA, and MUFA. The laboratory-reared larvae contained three to five times more essential PUFAs, EPA, and DHA. However, there were no differences in the total dry weight of the 4th instar larvae between the wild vs laboratory-reared larvae. Total FA in both larvae and habitats of An. albimanus and An. darlingi were positively correlated with the concentration of particulate organic carbon and nitrogen (POC, PON) in their respective habitats, but no such correlation was found for An. vestitipennis. PUFA are a good indicator of nutritional quality, although factors controlling the success of anopheline development from larval habitats are likely to be more complex and would include the presence of predators, pathogens, and toxins as interacting factors.

Assessment of metal pollution in the Lambro Creek (Italy)

This study assessed the effect of metal pollution in the Lambro Creek (Southern Italy). Water, sediment and biota were collected at six sampling sites (June) for metal concentration assessment (Cr, Cu, Ni, Pb and Zn). Sequential extraction was performed to determine the distribution of metals in different geochemical sediment fractions. The influence of pH and leaching time on the release of metals from sediment to the water column was investigated via remobilization tests. A battery of toxicity tests (Vibrio fischeri, Raphidocelis subcapitata, Phaeodactylum tricornutum, and Daphnia magna) with multi-endpoints (bioluminescence, growth inhibition, and immobilization) was used to determine the overall toxicity in sediment water extracts. The results showed that metals did not exceed the probable effect concentration levels, with Cr concentration exceeding the threshold effect concentration level at all sampling points except for the one closer to the source of the creek, suggesting potential negative effect on the biota. Considering the cumulative criterion unit, sediment contamination was moderate at all sampling sites, except for L3 and L5 where biota was exposed to a very high risk. With respect to sequential analysis, the most readily available fraction of metal can be generalised as Ni > Cr > Cu > Zn > Pb. For better understanding the fate of metals in the water-sediment environment, their biogeochemical cycles should also be investigated in small creeks including both fresh (watercourse) and saltwater (river mouth) sediments.

Trace Metals in the Bed Sediment of Small Urban Streams

Trace metals (TMs) are still a serious problem in urban streams because of their toxicity and continuing signifi- cant levels in the aquatic environment, especially in bed sediments. Concentrations of Cd, Cr, Cu, Ni, Pb and Zn were monitored in the sediments of several small streams in the Prague area. These streams differ in the main source of pollu- tion (combined sewer overflow - CSO, storm water drain - SWD, or waste water treatment plant - WWTP). The potential TMs hazard was assessed by several indexes, and the dependence of TMs concentrations on various sediment material characteristics was evaluated. The bioavailability of TMs was also assessed by comparing the binding strength of metals in the sediment and their concentrations in aquatic organisms in these creeks. Of the metals studied, Cd is the most avail- able from sediments, but the other metals were also easily released from the sediment to the liquid phase. There were also differences in TMs bioavailability from sediments of creeks with different main pollution source, and was higher in creeks impacted by WWTP and SWD.

Influence of potassium concentration gradient on stable caesium uptake by Calla palustris

The effect of potassium (K) concentration gradient on stable caesium (Cs) uptake by Calla palustris was studied under hydroponic conditions after eight-day exposure in a greenhouse experiment. The plants were exposed to two different concentrations of Cs (provided as 0.5 and 1 mM CsCl) and five different concentrations of K (provided as K2SO4 in 0.5, 1, 2, 5, and 10 mM). The results indicate negative dependence of Cs uptake on K concentrations for both Cs treatments. The application of K reduced the transfer of stable Cs from water to plant by about 44-72% for 0.5 mM CsCl and 56-74% for 1 mM CsCl. The highest efficiency of Cs removal from water was observed for plants in K+ deficient solutions (plants starving), with an efficiency 8.0% for plants cultivated in 0.5 mM CsCl and 9.4% for plants in 1 mM CsCl. An increasing concentration of K also supported translocation of Cs from roots to leaves. Higher translocation was observed for the treatments with lower level of Cs, where the concentration of Cs in leaves became higher than that in roots. The Cs uptake and translocations were affected not only by the external concentration of K, but also the external concentration of stable Cs. A high concentration of K in the environment protects the food chain from Cs uptake by plants, but lowers the efficiency of phytoremediation techniques.

The sediment of the Hostivar Reservoir (Prague, Czech Republic) as a memory of 45 years of pollution

Purpose The purpose of this paper is to evaluate the historical pollution of the Hostivar Reservoir (largest reservoir in Prague) sediment by metals, polyaromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB) and identify the trends in pollution of aquatic environment. Design/methodology/approach Core samples, 140 cm long, recording the 45-year history of the reservoir, were separated to 5 cm width subsamples (approximately 1.5 years of sedimentation) and analyzed for metals (Cd, Pb, Cu, Zn, Cr, Ni, Al), PAH and PCB. Following methods were used: US EPA 3051 for metals, US EPA 505 and US EPA 8082 A for PCB, and ISO 18287:2006 for PAH. Findings Most of the contaminants had the highest concentration at the beginning of the existence of the reservoir, suggesting that the contamination results from construction activities. Significant decrease of Pb occurred in the second half of the 1990s. It was caused by termination of the addition of lead as a detonation suppressant to the gasoline. Most concentrations of PAHs, PCBs and metals, except copper do not present eco-toxicological risk. Practical implications The results show the volume of priority pollutants removed from the reservoir by sediment extraction, and point risk to the terrestrial environment due to application of the sediment in the construction of a noise protecting wall. Originality/value The paper presents unique data about historical contamination of the largest reservoir in Prague, the capital of Czech Republic. It shows how the watershed and the construction phase of the dam cause a pollution of the reservoir sediment and possible environmental risk for aquatic biota.

Stable cesium (133Cs) uptake by Calla palustris from different substrates

The uptake of stable cesium (133Cs) by Calla palustris was evaluated from four different substrates: water, soil, keramzit (a clay granule) and water with the addition of a potassium compound, after an eight days exposure to a solution of 0.5mM cesium chloride. Stable cesium was used because it is commonly supposed that its uptake by plants is the same of that of radiocesium (137Cs). The plants were differentiated in their parts (roots, healthy leaves, dead leaves and flowers) and analyzed with ICP-MS. The lowest average concentration of absorbed Cs was found in plants exposed in soil (0.7mg/kg, S.D.=96.8), while the highest in plants exposed in water (147mg/kg, S.D.=51.7). During the experiment the water planted plants removed 31.6% of provided Cs while those planted in soil removed only 0.06%. The addition of potassium to water was tested because of the competition effect that arises between these two elements: this effect was confirmed with the result that the average uptake in the presence of potassium was lower (41mg/kg in exposed plants, S.D.=76.1). The uptake was also lower in the solid-based substrates (soil and keramzit), because of the known tendency of Cs to bind with soil particles, thus becoming less available to plants. There was no evidence that the different parts of the plant showed different uptake effectiveness, or that the health of the plant (evaluated with a qualitative method) had any effect on the uptake of Cs.

Changes of toxic metals bioavailability in urban creeks as a potential environmental hazard

The impact of different urban drainage structures (combine sewer overflow, stormwater drain and waste water treatment plant) on fate of toxic metals in urban creeks was studied on three creeks in the Prague area. The results show that bioavailability of toxic metals is affected by the type of urban drainage and environmental conditions. The bioavailability is significantly influenced by a type of urban drainage, while combine sewer overflows cause decrease of biological availability, storm water drains and a waste water treatment plant cause increase of bioavailability of toxic metals.