3.6 CHEMICAL CONTAMINATION OF SOIL

3.6.1 Soil Contamination Monitoring System

As in previous years, the monitoring of chemical contamination of soil in Prague reflected the needs of different city districts and the City of Prague. In 1995, sampling sites were located in the following districts and areas: Prague 1, Prague 14, Prague 15, Bechovice, Dablice, Dolni Chabry, Chuchle, Letnany, Reporyje, Zlicin, Slivenec and Draska Gully. In addition, monitoring continued on sites regularly monitored in the framework of the Information System on Prague Environment since 1981.

The analyses focussed on determining contents of heavy metals and, with some selected samples, also of nonpolar extractable substances (NES), polychlorinated biphenyls (PCB), chlorinated organic pesticides, chlorinated hydrocarbons and polycyclic aromatic hydrocarbons (PAHC).

As to analyses of samples taken on farming land, their results were evaluated using the criteria and limits set forth in Decree No. 13/1993 of the Law Gazette, on the protection of agricultural land fund. Insofar as other land is concerned, the analyses were evaluated using the limits laid down in the Methodological Directive of the Ministry of Agriculture of the Czech Republic, on standards and criteria applying to contaminated soil and polluted groundwater sanitizations in accordance with Act No. 17/1988 of the Law Gazette (Environmental Act).

Regularly monitored sites. Significant changes were observed at the following sites: Husova, Karlovo Square, 14. rijna Square, Smetanovo Quay and Delnicka Str., Rohan Isle or Kolbenovo Square, where increased levels of contamination by heavy metals, well above the background concentrations, were identified. The contamination remains concentrated in the central part of the city. The values have not shown any dramatic change over the whole monitoring period.

Slivenec Waste Dump, Draska Gully. The monitoring ordered by the Environmental Department of the Municipality of Prague. The experimental site established on the Slivenec Waste Dump shows relatively high variations of values and increased contamination (particularly zinc, cadmium, and also lead, copper and mercury). The variations are probably attributable to an uneven thickness of top deposits; on slopes, erosional processes sometimes expose waste materials. In some places, high contents of NES, PAHC and PCB were identified. It seems that the top cover of the waste dump (practically without any vegetation cover whatsoever) is sufficient. The materials are not contaminated by either heavy metals or organic substances. The absent vegetation cover is probably due to unsuitable materials (from the viewpoint of their physical and mechanical properties), namely soil excavated from building foundation pits, having been used for the top cover. Foul-smelling waste dump gas was found all over the site. Fields in the vicinity of the Draska Gully do not show any significant contamination by heavy metals or organic substances. However, their concentrations are somewhat higher on the gully slopes. The site merits a more detailed survey.

Prague 1. Based on analyses of samples taken on selected sites, the first district of Prague is substantially more contaminated by heavy metals and organic substances than other districts of Prague. This applies in particular to parks, open areas and playgrounds. High concentrations of heavy metals and organic substances were found in samples from Vrchlického Parks (close to the terminal), Vaclavské Square, Na Frantisku (street alley), Parizska, the playground near Karluv Bridge and other places. The soil in Fratiskanska Garden and the green area in the backyard of the Old Town Hall both received very unfavourable ratings.

Prague 14 (Kyje). The sites under observation did not show any significant contamination with heavy metals or nonpolar extractable substances. However, local contamination cannot be ruled out. Organic substances, monitored on four selected sites only, suggest local contamination which merits a more detailed survey (especially of sites of business or industrial activities).

Prague 15 (Horni Mecholupy). No significant contamination by heavy metals or non-polar extractable substances was observed. It is, however, possible that the situation may be worse along heavy-traffic roads, on sites where industrial and commercial activities are taking place, or there where contaminated materials (e.g. waste sludge) have been used for levelling purposes. Owing to the absence of any monitoring of organic substances, the sites in Prague 15 cannot be assessed from this viewpoint.

Bechovice. No significant contamination by heavy metals or non-polar extractable substances was observed. A locally increased level of contamination was registered in a small park off Ceskobrodska, a slightly higher concentration of heavy metals near the Bechovice 2 kindergarten, and higher contents of organic substances on a field near the SSZ gravel-coating plant.

Dablice. Save for the premises of PREFA, an ex-state-owned company, the section of Dablicka Str. near the Martinsky Creek, and the premises of the U Parkanu Elementary School, the area does not have any high concentrations of contaminants. It must be appreciated that, in spite of being located next to a huge landfill, the area is not contaminated by heavy metals and organic substances.

Dolni Chabry. No significant contamination by heavy metals or non-polar extractable substances was observed. However, there are some local increased concentrations.

Chuchle. The results suggest that company premises - Vodni Stavby (Water Structures) in Mala Chuchle - where samples were taken are highly contaminated by both heavy metals and organic substances. Agricultural land contains neither heavy metals nor non-polar extractable substances. PAHC concentrations are slightly above the permissible contamination limit. Free-range sampling sites and important nature elements do not show any significant contamination.

Letnany. Except for the playground at the Malkovského Kindergarten, no significant pollution by heavy metals was observed. Agricultural land (east of Beranovych) is contaminated with heavy metals. Additional contamination may be expected on sites where industrial and commercial activities are taking place, such as AVIA Letnany, Letnany Sugar Factory etc., where no samples have yet been taken.

Reporyje. A heavily contaminated spot was found at the railway bridge. The following sites show slightly increased concentrations of heavy metals and organic substances: the small park in the village square, sites along Smichovska and Ve Vyrech, agricultural land in Zadni Kopanina.

Zlicin. The results indicate that the topsoil on sampling sites does not contain any higher quantities of heavy metals. On the other hand, concentrations of organic substances exceed the permissible limit. The concentrations justify a more detailed survey (public parks at the pond in Sobin, the small park near U lipy and U Cekala). Nevertheless, the sampling sites seem to be substantially less contaminated than those in other administrative districts of Prague.

Selected results of the monitoring of contaminants (leaching with 2M nitric acid)

Source: PUDIS

Contents of lead, zinc and cadmium between 1981 and 1995 in samples taken in Karlovo Square, Prosek and Sarka

Source: PUDIS, IMIP

Soil contamination monitoring in city districts and on regularly monitored sites

Source: PUDIS

3.6.2 Geochemical Mapping of the Prague Agglomeration

Since 1994, the Czech Geological Institute has been working on a project of geochemical mapping of the Prague Agglomeration, which is funded by the Ministry of the Environment of the Czech Republic. Its objective is to determine the distribution of major contaminants, such as heavy metals and organic compounds of carbon, in topsoils in the territory of the city. The results have been experimentally assessed by the National Health Institute from the viewpoint of health threats the contamination poses to the population.

The systematic sampling of soils in the territory of the Prague Agglomeration was carried out using a regular sampling grid with a density of one aggregate sample (4 samples taken from depths down to 20 centimetres) per square kilometre. The samples were analyzed for more than 20 elements (in particular heavy metals); in addition, the contents of polyaromatic hydrocarbons (PAHC) and polychlorinated biphenyls (PBC) were determined as well. The results were processed at GIS and plotted into single-element maps.

Samples of dust were taken at several busy crossroads in Prague, which have been analyzed for their contents of platinum and platinum-group metals the concentrations of which, based on experience of other European cities, keep increasing and correlate with higher concentrations of lead.

The assessment of the degree of risk posed by each element is also based on the knowledge of their forms of occurrence in soil. All the elements surveyed, except copper, occur mainly in association with iron and manganese oxides. Save for nickel and cobalt, the degree of risk from the viewpoint of their chemical association is fairly high.

Organic compounds of carbon were analyzed using samples taken on the same sites as those analyzed for the contents of trace elements. At the moment, analyses of PAHC comprising fifteen components are available; the information presented in the maps is an aggregate PAHC value. Contents of PCB will be available later. Health limits applying to concentrations of trace elements and other contaminants in urban soil have not yet been set in a binding manner. Using the above data, the National Health Institute will prepare supporting documentation the purpose of which will be to assess how the population is affected by selected contaminants present in urban soil.

Preliminary findings suggest that increased concentrations of the contaminants under survey are found in the central part of the agglomeration. Principal sources of the contaminants include heating systems burning fossil fuels and automobile traffic. Some of the contaminants (mercury) seem to be attributable to industrial leakages.

Geochemical mapping of the Prague Agglomeration Arsenic, Cadmium

Source: CGU

Geochemical mapping of the Prague Agglomeration Lead, Mercury

Source: CGU

Geochemical mapping of the Prague Agglomeration Copper, Zinc

Source: CGU

Geochemical mapping of the Prague Agglomeration pH, PAHC

Source: CGU

3.7 ENVIRONMENTAL BIOMONITORING

3.7.1Regular Monitoring of the Living Component on Selected Sites

To enable assessments of the ongoing changes of the environment in Prague, the living component is also monitored. As a matter of fact, data pertaining to lower animal species is often indicative of adverse consequences of environmental deterioration with respect to humans. The changes that are identified demonstrate the aggregate impact of all factors which are often monitored separately. Within the Information System on Prague Environment, the biomonitoring programme is conducted by the Czech Association of Nature Conservationists on the following six natural model sites, generally in five-year cycles:

In 1995, two nearby areas were surveyed, namely Pitkovické Valley and Uhrineves Warren. Typical features of the former include a higher number of stand types and a more varied terrain configuration. As a result, the number of plant and animal species is higher as well. Anthropogenic impacts are represented by industrial, agrochemical, traffic and residential pollution transferred through the atmosphere. Another negative phenomenon is the existence of a huge waste dumping site off Uhrineves, the operation of which, however, has been terminated. The situation of Pitkovické Valley may deteriorate as a result of the construction of either of two alternative highway routes in the vicinity. Streams flowing through the area are polluted as well.

The surveys, analyses and assessments have been conducted for the following groups:

Like with Divoka Sarka and Prokopské Valley, a comparison with results of previous surveys and inventories indicates not just a deceleration of degradation processes, but also an improvement of bioindicators in most of the groups since 1990. Apart from the closing down of the landfill, the impacts of which seems to be local, the improvement is likely to be attributable to a general decline of extensive industrial production and increasing pressures to reduce industrial pollution and use of agricultural chemicals.

Although both areas can be viewed as relatively stabilized and showing signs of revitalization, the bioindicators in the Pitkovicky Creek valley are generally more favourable than those for the Uhrineves Warren.

Pitkovické Valley, Higher veinous plants

Source: CSOP

3.7.2 Monitoring of Occurrences of Borelias in Ticks

In 1995, the Public Health Office of the City of Prague continued to monitor the incidence of viruses causing Lyme boreliosis and tick-induced encephalitis in ticks living on long-term monitoring sites within city limits. The survey was conducted in cooperation with the National Health Institute and District Public Health Offices.

In 1995, the highest average percentages of ticks containing the virus causing Lyme boreliosis were observed in Stromovka (11.3%), Klanovice (11.2%) and Petrin Hill (11.0%). On the other hand, the lowest percentages were observed in Krc, Troja and Hostivar (8.0 %).

Compared to 1994, there was a marked increase of the above indicator in Stromovka, Petrin Hill, Klanovice, but also Vitkov, Troja, Dablice Forest and Hostivar (an average increase equal to at least a hundred percent).

All in all, it may be concluded that the virus causing Lyme boreliosis continues to be present in ticks living on green sites both in the centre and suburban parts of Prague, i.e. in recreational areas used by inhabitants of Prague. Compared to previous years, average percentages of ticks containing the virus causing Lyme boreliosis are higher and relatively homogeneous (8.0 to 11.3%).

3.8 AEROBIOLOGICAL MONITORING IN PRAGUE BETWEEN 1993 AND 1996

Approximately a third of all children in the Czech Republic suffer from an allergy. Allergies are often induced by airsuspended allergenic substances, also known as aeroallergenes, in particular pollen grains and spores of moulds. The pollen-induced allergies are difficult and costly to treat. As a rule, the treatment hinges on preventing the patient's contact with pollen allergenic substances as perfectly as possible. Therefore, it is the task of the Pollen Information Service (PIS) to provide timely and accurate information on the presence of pollen allergenic substances in the atmosphere to medical care personnel and patients alike, to issue warnings if the pollen concentration rises above the common average, and to forecast the course of the pollen season of which there are year-to-year variations.

The office of the Pollen Information Service in Prague was opened in March 1993. Until June 1995, it was housed in the polyclinic in Karlovo Square, but it has been moved to the National Health Institute in Srobarova for operational reasons.

In Prague and in the Czech Republic as well, the most important of spring airsuspended allergenic substances (among which tree pollens prevail) are birch (Betula) pollen and pollens of the entire Betulaceae family (so-called crossbred reactivity). In the summertime, grass (Poaceae) pollens take over. At that time, the concentration of mould spores (particularly the Cladosporium and Alternaria geni) is increasing as well. Typical for the autumn time is a prevalence of weed pollens, in particular wormwood (Artemisia). August also marks the peak of the season of mould spores the concentrations of which in the air exceed the aggregate concentration of all pollens by an order of magnitude.

The 1996 pollen season in Prague was very weak. Compared to previous years and due to a very late advent of spring and warm weather, it started much later than usual. The pollen season of hazelnut (Corylus) and alder (Alnus), which usually starts in the end of February or early in March at the latest, took place in April, together with the pollen season of birch (Betula) and ash (Fraxinus), which is an extremely unusual phenomenon. Birch and ash did not show any delay and the rest of the season was normal. Similarly, concentrations of pollens of most of the monitored plant species was significantly lower than in previous years.

Unfortunately, the monitoring station was out of operation during the anticipated peak season of wormwood /Artemisia); consequently, the representation of this allergenic substance in the air cannot be assessed properly for 1996.

Presence of pollens in the air, Prague 1993 - 1996 Betula, Artemisia, Poaceae

Source: PIS