Effect of NaCl road salt on the ionic composition of soils and Aesculus hippocastanum L. foliage and leaf damage intensity.

We investigated the accumulation of sodium chloride in roadside soils and common horse chestnut Aesculus hippocastanum L. under urban conditions to evaluate changes in soil and leaf ionic content and their relationship with foliar damage, considering the visual assessment of trees of the same health status. A total of 15 field sites were assessed in late June 2016. The analysis included soil granulometric composition, pH, electrical conductivity, and the content of Cl-, Na+, K+, Ca2+, and Mg2+ ions in soil and foliage samples. The results showed increased salinity and alkalization of roadside soils together with the decreased magnesium content. Foliage samples manifested significantly higher concentrations of Na+ and Cl-. A wide range of Cl- content was noted in leaves (2.0-11.8% d.w.) regardless of their damage index. On the contrary, leaf damage was strongly correlated with increasing Na+ concentrations and decreasing K+ and Mg2+. A severe imbalance of nutrients, and therefore poor urban tree vitality, can be attributed to the excessive accumulation of de-icing salt. However, further research would be needed to clarify the discrepancy between the extent of leaf damage and chloride content.

The potential of the Phytotoxkit microbiotest for hazard evaluation of sediments in eutrophic freshwater ecosystems.

The applicability of the Phytotoxkit microbiotest for toxicity assessment of sediments in eutrophic freshwater ecosystems was evaluated. Sediments were collected from Turawa dam reservoir (southwestern Poland) which, for years, has been subjected to a marked nutrient enrichment and heavy metal contamination. The test plant species were exposed to whole sediments, solid phases of sediments, and pore waters. Phytotoxicity was estimated on the basis of seed germination and root elongation measurements, combined into an overall germination index (GI). For pore waters, the majority of GI values were not statistically different from the controls, which was consistent with chemical data. For solid phases and whole sediments, GI values showed diversified effects ranging from growth stimulation to growth inhibition. The results obtained vary depending on the plant species and the type of sediment samples. Generally, tests with solid phases of sediments showed phytostimulation, suggesting that higher amount of nutrients adsorbed on organic matter-rich sediments might conceal the inhibitory impact of heavy metals (Cd, Cr, Cu, Mn, Ni, Pb, and Zn). However, this beneficial impact is indicative of a significant nutrient load and, with respect to aquatic ecosystems, its potential resuspention that might accelerate the reservoir eutrophication. Under appropriate conditions heavy metals exerted stronger negative impact on plants. Tests with whole sediments had a higher acidity (pH 5.85) and showed adverse effects, though plant responses vary from inhibition (Lepidium sativum) to stimulation (Sorghum saccharatum). The study demonstrated variability in toxicity of contaminated nutrient-rich sediments as well as effectiveness and usefulness of the Phytotoxkit microbiotest as a practical and reliable tool for evaluation of the hazard of eutrophic ecosystems to higher plants.

Comparison of the Phytotoxkit microbiotest and chemical variables for toxicity evaluation of sediments.

The main objective of the research was to evaluate the suitability of the Phytotoxkit microbiotest as a tool for hazard assessment of sediments. The concentrations of oil derivatives, polycyclic aromatic hydrocarbons (PAHs), and heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn) were determined in sediment samples collected from the urban canal in Opole (Poland), in order to obtain a general insight of the level of sediment contamination. Phytotoxicity of sediments was estimated on the basis of seed germination and root elongation measurements, combined into an overall germination index (GI). The results revealed spatial and vertical differentiation in sediment contamination. A good correlation was obtained between organic matter content and the concentrations of particular sediment pollutants. Values of correlation coefficients at P < 0.05 ranged from 0.3246 for oil derivatives to 0.8929 for PAHs. Phytotoxicity tests, carried out on the monocotyl Sorghum saccharatum and the dicotyls Sinapis alba and Lepidium sativum, showed different responses of the three plant species to sediment samples ranging from growth inhibition to growth stimulation. The GI values revealed the following increasing order of plant sensitivity to contaminated sediments: L. sativum < S. alba < S. saccharatum. The study demonstrated that the Phytotoxkit microbiotest was effective in identifying toxic samples. However, sediment organic matter content and grain-size distribution had a significant impact on both sediment contamination and higher plantresponses to contaminated samples. The implication of these findings are discussed.

Effect of deicing salts on urban soils and health status of roadside trees in the Opole region.

This article reports on a study whose aim was to evaluate the impact of snow removal salts on urban soil properties and the health of roadside trees. The evaluation was done by chemical analyses of soil samples and plant matter combined with toxicity testing, performed with a Protoxkit F, a protozoan microbiotest. Samples were collected at 45 locations on three main roads in the town of Opole (Poland). The roads differed in the snow removal technology and amount of chemical substances (mostly NaCl) used on them during the winter. The study showed that when soil was exposed to a high level of NaCl, it tended to be more alkaline and also exhibited increased content of Na(+) and Cl(-). The toxic effects of the soil extract on protozoa appeared at 26.0 mg Na(+)/100 g soil dry mass (s.d.m.) and 12.0 mg Cl(-)/100 g s.d.m., whereas salt injury symptoms (chlorosis and necrosis of the edge of leaf blades) appeared at 13.2 mg Na(+)/100 g s.d.m. and 3.9 mg Cl(-)/100 g s.d.m., becoming more severe at 26.0 mg Na(+)/100 g s.d.m. and 12.0 mg Cl(-)/100 g s.d.m. because of extensive necrosis and defoliation. The lysimetric experiment, which was used to test soil samples collected from the city park area, indicated that salt plays a significant role in the pollution of soil in urban areas, with the least toxic salt being CaCl(2).