Heavy metals when present in amounts equal to the geochemical background do not interfere with the soil metabolism, which is associated with the growth and development of soil microorganisms as well as the processes of synthesis and re-synthesis, governed by intra-and extracellular enzymes. In the said concentrations, heavy metals do not cause undesirable changes in the development of plants. On the contrary, such elements as copper and zinc are essential constituents of physiological processes in all living organisms, including microorganisms and plants. Some soils suffer from zinc and copper deficits, which is why they are enriched with fertilizers containing copper or zinc to satisfy the nutritional requirements of crops. Cadmium is different in that its essential role in the proper functioning of living organisms has not been proven yet. In Poland, soils contaminated with heavy metals, including cadmium, copper and zinc, occur only locally. The purpose of this study has been to discuss the characteristics of these elements in terms of the chemical properties and the role in the natural environment, the effect they produce on plants when present in excessive concentrations in soil and the response of soil microbes and enzymes to such contaminants. Crops cultivated on soil with an elevated content of heavy metals typically present inhibited growth, reduced transpiration, chlorosis of leaves, limited germination of seeds and deformations of the root system. The effect induced by heavy metals is more pronounced in the early development of plants. Mobility and plant availability of heavy metals depend on a series of factors, for example the soil pH, content of organic matter, grainsize composition of soil, content of iron and manganese oxides, soil sorption capacity and the type of metal. Higher bioavailability of heavy metals is observed in soils with a low content of humic acids. As the soil pH increases (within 6.5-7.5), metals, especially zinc and-to a lesser degree-copper become less toxic to plants.

The aim of our study was to estimate the participation of prostaglandin E 2 (PGE 2 ) in the contractile activity of inflamed porcine uterus. On day 3 of the oestrous cycle, 50 ml of saline or 50 ml of Escherichia coli suspension, containing 10 9 colony-forming units/ml, was injected into each uterine horn in the control or experimental group, respectively. Seven days later the uteri were collected. Endometritis developed in all bacteria-inoculated gilts. Endometrium/myometrium and myometrium strips were incubated with PGE 2 alone or together with PGE 2 receptor (EP) subtypes (EP 2 , EP 4 , EP 1 and EP 3 ) blockers: AH 6809 (BEP 2 ), ONO-AE 2 (BEP 4 ), ONO-AE 3 -240 (BEP 1 ) and SC19220 (BEP 3 ), respectively. In the control group, PGE 2 (10 -8 and 10 -7 M) increased the intensity of contractions in endometrium/myometrium, and at the higher dose in myometrium. PGE 2 (10 -8 M) decreased the contraction intensity of the strips from inflamed uteri. After the use of BEP 2 , PGE 2 (10 -7 M) increased the values of this indicator in endometrium/myometrium and myometrium from the control gilts. In these animals, PGE 2 (10 -8 M) in the presence of BEP 4 reduced the contraction intensity in endometrium/myometrium. In the bacterial group, PGE 2 (10 -8 M) in the presence of BEP 2 and BEP 4 enhanced the intensity of contractions in myometrium. Similar reaction was evoked by PGE 2 (10 -7 M) in endometrium/myometrium of the inflamed uteri in the presence of BEP 4 . The intensity of contractions in myometrium from the inflamed uteri significantly decreased after the use of BEP 1 and PGE 2 (10 -7 M). PGE 2 (10 -7 M) administered after BEP 3 , significantly decreased the intensity of contractions in myometrium of the control gilts. These results show that PGE 2 decreases the contraction intensity of inflamed porcine uteri. Further studies are needed to closely determine the role of PGE 2 and other prostanoids in the contractile activity of inflamed uterine tissue.

The use of fungicides in crop protection still effectively eliminates fungal pathogens of plants. However, fungicides may dissipate to various elements of the environment and cause irreversible changes. Considering this problem, the aim of the presented study was to evaluate changes in soil biological activity in response to contamination with azoxystrobin. The study was carried out in the laboratory on samples of sandy loam with a pH of 7.0 in 1 Mol KCl dm . Soil samples were treated with azoxystrobin in one of four doses: 0.075 (dose recommended by the manufacturer), 2.250, 11.25 and 22.50 mg kg −1 soil DM (dry matter of soil). The control soil sample did not contain fungicide. Bacteria were identified based on 16S rRNA gene sequencing, and fungi were identified by internal transcribed spacer (ITS) region sequencing. The study revealed that increased doses of azoxystrobin inhibited the growth of organotrophic bacteria, actinomycetes and fungi. The fungicide also caused changes in microbial biodiversity. The lowest values of the colony development (CD) index were recorded for fungi and the ecophysiological (EP) index for organotrophic bacteria. Azoxystrobin had an inhibitory effect on the activity of dehydrogenases, catalase, urease, acid phosphatase and alkaline phosphatase. Dehydrogenases were found to be most resistant to the effects of the fungicide, while alkaline phosphatase in the soil recovered the balance in the shortest time. Four species of bacteria from the genus Bacillus and two species of fungi from the genus Aphanoascus were isolated from the soil contaminated with the highest dose of azoxystrobin (22.50 mg kg −1).

The aim of this study was to determine the effect of three active substances, diflufenican, mesosulfuron-methyl and iodosulfuron-methyl-sodium, applied in combination, on soil microbial counts, the structure of soil microbial communities, activity of soil enzymes and their resistance to the tested product, the biochemical indicator of soil fertility, and spring wheat yield. Soil samples with the granulometric composition of sandy loam with pHKCl 7.0 were used in a pot experiment. The herbicide was applied to soil at seven doses: 0.057 (dose recommended by the manufacturer), 1.140, 2.280, 4.560, 9.120, 18.240 and 36.480 mg kg−1 soil DM. Uncontaminated soil served as the control treatment. It was found that a mixture of the tested active substances increased the counts of total oligotrophic bacteria and spore-forming oligotrophic bacteria, organotrophic bacteria and actinomycetes, decreased the counts of Azotobacter and fungi, and modified the structure of soil microbial communities. The highest values of the colony development (CD) index and the ecophysiological (EP) index were observed in fungi and organotrophic bacteria, respectively. The herbicide applied in the recommended dose stimulated the activity of catalase, urease and acid phosphatase, but it had no effect on the activity of dehydrogenases, alkaline phosphatase, arylsulfatase and β-glucosidase. The highest dose of the analyzed substances (36.480 mg kg−1) significantly inhibited the activity of dehydrogenases, acid phosphatase, alkaline phosphatase and arylsulfatase. The values of the biochemical soil fertility indicator (BA21) decreased in response to high doses of the herbicide. Urease was most resistant and dehydrogenases were least resistant to soil contamination with a mixture of diflufenican + mesosulfuron-methyl + iodosulfuron-methyl-sodium. The analyzed herbicide had an adverse influence on spring wheat yield, and doses of 18.240 and 36.480 mg kg−1 led to eventual death of plants.