Accumulation of heavy metals and antioxidant responses in Pinus sylvestris L. needles in polluted and non-polluted sites

Abstract

The purpose of this study was to determine the concentrations of heavy metals (cadmium, iron, manganese, lead and zinc) in current-year, 1-year old and 2-year old needles of Pinus sylvestris L. Trees were from three heavily polluted (immediate vicinity of zinc smelter, iron smelter and power plant) and three relatively clean sites (nature reserve, ecologically clean site and unprotected natural forest community) in southern Poland. Analysis also concerned the antioxidant response and contents of protein, proline, total glutathione, non-protein thiols and activity of guaiacol peroxidase (GPX) in the needles. Generally, in pine needles from the polluted sites, the concentrations of the metals were higher and increased with the age of needles, and in most cases, antioxidant responses also were elevated. The highest levels of Cd, Pb and Zn were found in 2-year old pine needles collected near the polluted zinc smelter (respectively: 6.15, 256.49, 393.5 mg kg −1 ), Fe in 2-year old pine needles in the vicinity of the iron smelter (206.82 mg kg −1 ) and Mn in 2-year old needles at the ecologically clean site (180.32 mg kg −1 ). Positive correlations were found between Fe, Mn and Pb and the content of proteins and NPTs, between Cd and non-protein –SH groups, and between Zn and proline levels. The activity of GPX increased under the influence of Mn, while glutathione levels tended to decrease as Mn levels rose. The data obtained show that the levels of protein and non-protein –SH groups may be useful in biological monitoring, and that these ecophysiological parameters seem to be good evidence of elevated oxidative stress caused by heavy metals.