The study analyses the efficiency of pollutant removal by three small wastewater treatment plants located in the rural areas of the Lublin province. The first of them is a household plant having a soil-plant bed with Salix viminalis. The second is a BATEX-B5-type household plant with a filter drain. The third one is a small treatment plant with Phragmites australis. Investigations carried out in 2001 revealed that the plants did not always meet the expectations as the effluents were not adequately clean and contained wastes, mostly bionic compounds, in concentrations exceeding the relevant standards. It is suggested that the development and modernisation of the plants might improve the effects of pollutant removal.

The efficiency of sewage treatment in the ground bed under the subsurface sewage disposal field was tested in laboratory conditions using synthetic sewage. The ground bed was composed of dusty sand. The experiment determined the following indicators: suspended solids, BOD₅, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, phosphates and pH. In the sewage filtered through the ground bed a considerable increase in the concentration of nitrate nitrogen was observed. The values of other indicators of the treated sewage were within the standard range.

Based on the data from the state monitoring system of Poland, the concentrations of nitrogen and phosphorus in the waters of the Ner river and its tributaries were determined for the years 1992–1997. The total and unit loads were calculated and compared with those of other tributaries of the Warta river. The variability of results over six years was analysed in relation to the data about land use, soil type, weather conditions and the characteristics of point-pollution sources in the catchment area.

One of the processes preparing sewage sludge for agricultural utilisation is its biological processing using Eisenia fetida. The process is best applied to the sewage sludge composted with plant matter or other organic components. It allows a rapid and efficient change in compost properties, making it possible to obtain useful fertilisers, so-called vermicomposts. The investigations aimed to determine the effect of the levels of selected heavy metals in tannery composts and vermicomposts on the concentrations of these metals in the earthworm body and crop biomass. It was found that the copper, zinc, cadmium and chromium contents of the earthworm biomass depended on their contents of the substratum. The levels of heavy metals in the crops varied according to plant species, being as a rule lower in the vermicompost treatments than in the mineral or farmyard manure treatments. The plants stored the absorbed chromium primarily in their root systems. The excessive chromium content of vermicomposts did not cause its excessive accumulation in the crop biomass.

Słowa kluczowe: chrom, osady ściekowe, ekstrakcja sekwencyjna

The effect of soil pollution levels on the yielding of maize was investigated to determine whether this species can be used for remediating soils contaminated with cadmium, lead, nickel, copper and zinc. The yields of tops and roots significantly depended on the concentration of heavy metals in soil. The metal contents of maize plants were in the following range (mg ∙ kg^-1 d.m. of soil): Cd – 0.32–19.21; Pb – 0.84–11.09; Ni – 0.70–165.13; Cu – 2.04–30.46; Zn – 36.04–1084.11. The heavy metals studied can be arranged in an order according to the decreasing values of their utilisation (%) by maize. The order is as follows: Zn, Cd, Cu, Ni and Pb, which indicates that maize utilised zinc to the greatest, and lead to the smallest extent. The results of the studies show that maize is suitable for the phytoextraction of heavy metals from soil.

Phytosociological data from 25 transects of rural forest parks located in the West Masurian District were used to determine changes in the structure and species composition of various layer of the tree stand and underwood. The pattern of changes in the undergrowth was defined on the basis of the physical and chemical properties of soil. The form of the stand and the underwood layer tended to become similiar to that occurring in nature. The parks have not been maintained for a long time and the undergrowth layer showed differences according to the clay fraction and humus contens of soil, light conditions and available nitrogen and phosporus.

Many Polish cities have central heating systems which consist of a main heat-generating plant and underground pipelines distributing heat to customers. Heating networks heat the ground, thus promoting the development of plant communities of atypical thermal and humidity characteristics. The study presents changes occurring over 2000–2002 in the floristic composition of lawns situated above heating pipelines in Kraków. In the most heated areas two different plant communities appear during a year and there are also periods with no vegetation. In summer, when air and ground temperatures are high and soil humidity is low, thermophilous species of foreign origin predominate; these are small love-grass (Eragrostis minor) and large crabgrass (Digitaria sanguinalis). In autumn and winter, when water is not a limiting factor, a community consists mainly of common chickweeds (Stellaria media) and annual meadow grass (Poa annua). The most prevalent species in both communities are annual species which wait out the unfavourable conditions in the form of seeds. On the largest part of lawn area above heating pipelines the heating effect is quite week and contributes mainly to the prolongation of the vegetation period and the acceleration of phenological phases.

Modern weather prediction is based on the data from the networks of automatic meteorological stations combined with the observations from meteorological satellites. When the measurement series are broken, the accuracy of a weather forecast is lowered. The research was aimed to develop a new technology of supplementing by means of artificial neural networks the incomplete series of air temperature measurements made by automatic meteorological stations. The temperature data were obtained from hourly measurements performed in 1984 at the Wrocław Swojec meteorological station located in Lower Silesia. Three perceptrons with a single hidden layer were developed and applied to complete 3-, 6- and 12-hour registration breaks. The results showed that neural networks may provide a useful tool for supplementing broken air temperature measurement series.

Many agronomic and environmental models require the input of daily meteorological data. When long series of historic data are lacking, necessary data can be simulated by mathematical models called data generators. There are several well-known generators of daily series of meteorological data for a single geographical point with a known climatic profile, however, there is still demand for generating data simultaneously for several points with spatial relationships being taken into account. The model presented in this work produces possible daily sequences of precipitation, maximum and minimum air temperature and sunshine for several sites, taking into consideration correlations between them. The model was validated using the data form the Wrocław, Leszno and Kłodzko meteorological stations. Various statistical tests were carried out to detect significant differences in the means, dispersions and correlations for the observed and generated data. The comparisons showed a high consistence of the data and a good effectiveness of the method.

Insolation, air humidity at 1 pm, precipitation, the number of days with rain, 10-day air temperature and wind speed in Wielkopolska were studied based on the records from the meteorological stations of Piła, Poznań, Koło, Leszno and Kalisz for the years 1980–1998. Analysis included also the bioclimatic conditions of the region, such as the grade of thermal ardourness, wind power and the cooling potential of the air (H). It was found that the weather conditions of Wielkopolska are comfortable, particularly during the period of increased tourist activity, that is from the end of June to the end of August. The increased insolation in May and the high (as compared to other regions of Poland) air temperature are expected to extend the holiday period in the countryside.