Needle pigment responses of Pinus massoniana L. to soils polluted with the heavy metals Zn, Pb and Cu

The effects of high Cu, Pb, and Zn concentrations on pigments of Pinus massoniana L. (PML) growing near the Dabaoshan Pb-Zn polymetallic mine were evaluated. A total of 19 samples of PML needles and 15 samples of soil were collected near the mine and at a nearby background site to compare heavy metal (HM; Zn, Cu, Pb) accumulations. A 2D scatter plot was used to study the relationships between the pigments and each metal element. PML needles collected from the mining area had a significantly higher content of Pb (24.5 mg/kg) and Cu (26.1 mg/kg) than needles collected from the background site (Pb: 2.8 mg/kg, Cu: 6.7 mg/kg). The HM concentrations in the needles were positively correlated with the pigment contents (chlorophyll a, chlorophyll b and carotenoids) . This suggests that PML can adapt to HM stress and even promote growth within a certain range. In contrast, when the HM content in needles reached very high values (Cu: 50 mg/kg, Pb: 60 mg/kg, and Zn: 110 mg/kg), the normal physiological and biochemical functions were hindered. PML is highly resistant to HM pollution, making it a candidate for reforestation and restoration of Pb and other HMs in mine areas.