Determination of heavy metal and mineral nutrient levels in an endangered endemic: centaurea kilaea; implications on conservation

Abstract

Centaurea kilaea Boiss. (Syn: Acosta kilaea (Boiss.) Holub) is a perennial endemic plant native to the Black Seacoast of northwestern Turkiye, and is listed among the endangered species in the Red DataBook of Plants ofTurkey. C. kilaea has undergroun stolons, stem is oblique or upright, 40-80cm long and richly branched at the top.Leaves may be lyrate or pinnatisect, with dense white or gray hairs. Flowers are purple and they bloom in June –August. Achenes can be 1.3-4.4 mm long, 0.3-2.0 mm wide, and pappus 1.5-4.5 mm long. They show a widedistribution in sand dunes at altitudes of 1-20 m starting from the sea coast, and can be seen as far as severalhundred meters inland.C. kilaea, like other endemic plants, is a plant that has adapted to the special ecological and physical characteristicsof the regions where it grows. One of the ways to better understand the distribution of this plant is to profile themineral element and heavy metal levels of the soil where it grows and to compare the levels of the same elementsin different organs of the plant with the levels in the soil. Based on this idea, the root, stem and leaf parts from 6different samples and 2 different C. kilaea populations were dried and the level of 15 different elements (Al, B,Ca, Cd, Cr, Co, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Zn) in these organs was measured with ICP-OES (InductivelyCoupled Plasma – Optical Emission Spectroscopy). The measurements were compared with the soil samples takenfrom the same regions and the accumulation and tolerance level of the plant was evaluated.When we examine the soil values, levels of Na, Co and K elements were quite low; Cd, Mn, Pb and Ni elementswere within the lower limit; and B, Ca, Cr and Cu elements are at normal values. It has also been observed thatMg and Zn levels are at the upper limits and Al element is found in excess in the soil samples.For plant parts, Al, B, Ca, Cd, Co, Fe, Mg, Mn, Na, Ni, Pb and Zn contents of all plant parts from both locationswere within the normal limits. Cr and Cu levels were found to be higher than expected and accumulated in leafand root samples. K levels were under normal values in soil samples where as greatly elevated in plant parts asexpected. Al levels were found to be higher in soil samples however the amount of Al in plant parts were found tobe within the normal limits. Exceptionally low levels of Cd and Pd in soil samples is interpreted as favourable interms of environmental pollution.When all findings were taken into consideration, C. kilaea can be regarded as being in a delicate balance with itsenvirons and must be under constant monitoring for deteriorating environmental conditions.However, it was observed that the amounts of mineral elements and heavy metals in the soil samples taken fromKilyos were higher than the soil samples taken from Şile.Keywords: Endangered plants, plant ecology, mineral nutrition, heavy metal stress