Landfills have been identified as potential sources of heavy metal pollution of the environment. The municipal solid waste Łubna landfill is one of the largest landfills in Poland. Its impact on heavy metal pollution (Cd, Pb, Zn, Cu, and Cr) of groundwater, soil and plants has been thoroughly evaluated. Elevated levels of contamination have not been recorded in the vicinity of the landfill. The concentrations of heavy metals in soil from the vicinity of the landfill were similar to the geochemical background levels for the forest and farming soils of central Poland. The concentrations of heavy metals in European goldenrod (Solidago virgaurea L.) and grasses (Poaceae) did not exceed the baseline concentrations and did not indicate environmental pollution by heavy metals. The levels of the metal concentration in groundwater did not exceed the standards established for water intended for consumption.
The present and future air contamination by mercury is and will continue to be a serious risk for human health. This publication presents a review of the literature dealing with the issues related to air contamination by mercury and its transformations as well as its natural and anthropogenic emissions. The assessment of mercury emissions into the air poses serious methodological problems. It is particularly difficult to distinguish between natural and anthropogenic emissions and re-emissions from lands and oceans, including past emissions. At present, the largest emission sources include fuel combustion, mainly that of coal, and “artisanal and small-scale gold mining” (ASGM). The distinctly highest emissions can be found in South and South-East Asia, accounting for 45% of the global emissions. The emissions of natural origin and re-emissions are estimated at 45–66% of the global emissions, with the largest part of emissions originating in the oceans. Forecasts on the future emission levels are not unambiguous; however, most forecasts do not provide for reductions in emissions. Ninety-five percent of mercury occurring in the air is Hg0—GEM, and its residence time in the air is estimated at 6 to 18 months. The residence times of its HgII—GOM and that in Hgp—TPM are estimated at hours and days. The highest mercury concentrations in the air can be found in the areas of mercury mines and those of ASGM. Since 1980 when it reached its maximum, the global background mercury concentration in the air has remained at a relatively constant level.
Soil contamination caused by the NaCl used to de-ice slippery roads in winter is now recognized as one of the major causes of nutrient disorders and death in urban trees. It is believed that polyisoprenoids may have a specific role in the adaptation of plants to adverse conditions and habitats; it is further believed that in the cell, they may exhibit a protective effect in response to biotic and abiotic stress. The aim of this study was to evaluate the effect of salt stress on the content of prenol lipids in the leaves of Crimean linden (Tilia 'Euchlora'). The Cl content in the slightly damaged ("healthy") leaves averaged 0.96%, while that in the heavily damaged ("sick") leaves averaged 2.02%. The leaves of control trees contained on average 0.57% Cl. The Na contents in the healthy and damaged leaves were 208 mg/kg and 1038 mg/kg, respectively, and the Na content in the control areas was 63 mg/kg. A mixture of polyprenols consisting of four compounds, prenol-9, prenol-10, prenol-11 and prenol-12, was identified in the leaves of Crimean linden. This mixture was dominated by prenol-10 (2.16-6.90 mg/g). The polyprenol content was highest in the leaves of "healthy" trees (approximately 13.31 mg/g), was lower in the case of "sick" trees (approximately 9.18 mg/g), and was the lowest in the control trees (mean 4.71 mg/g). No changes were observed in the composition of the mixture of polyprenols under these conditions. The results suggest that polyprenols may affect the accumulation of Cl in leaves. This phenomenon is evidenced by the high content of prenols in the leaves of trees considered "healthy" but growing under conditions of increased soil salinity and the lower content of prenols in the leaves of the "sick" and control trees. It is advisable to further investigate the role of prenol lipids in the leaves of trees subjected to salt stress.
The study was focused on assessing the presence of arabinogalactan proteins (AGPs) and pectins within the cell walls as well as prenyl lipids, sodium and chlorine content in leaves of Tilia x euchlora trees. The leaves that were analyzed were collected from trees with and without signs of damage that were all growing in the same salt stress conditions. The reason for undertaking these investigations was the observations over many years that indicated that there are trees that present a healthy appearance and trees that have visible symptoms of decay in the same habitat. Leaf samples were collected from trees growing in the median strip between roadways that have been intensively salted during the winter season for many years. The sodium content was determined using atomic spectrophotometry, chloride using potentiometric titration and poly-isoprenoids using HPLC/UV. AGPs and pectins were determined using immunohistochemistry methods. The immunohistochemical analysis showed that rhamnogalacturonans I (RG-I) and homogalacturonans were differentially distributed in leaves from healthy trees in contrast to leaves from injured trees. In the case of AGPs, the most visible difference was the presence of the JIM16 epitope. Chemical analyses of sodium and chloride showed that in the leaves from injured trees, the level of these ions was higher than in the leaves from healthy trees. Based on chromatographic analysis, four poly-isoprenoid alcohols were identified in the leaves of T. x euchlora. The levels of these lipids were higher in the leaves from healthy trees. The results suggest that the differences that were detected in the apoplast and symplasm may be part of the defensive strategy of T. x euchlora trees to salt stress, which rely on changes in the chemical composition of the cell wall with respect to the pectic and AGP epitopes and an increased synthesis of prenyl lipids.
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