نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه زیستشناسی، دانشکده علوم، دانشگاه پیام نور، تهران- ایران
2 گروه زیستشناسی، دانشکده علوم، دانشگاه فرهنگیان، اصفهان- ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
The present study was devoted to investigate the concentration of lead (Pb) in the tailings of Tang-e Douzan lead–zinc mine then determine the growth factors and the lead accumulation in metallicolous and non-metallicolous populations of Marrubium cuneatum in 2018 at the university of Isfahan. The both plant populations were transferred to hydroponic mediums and after proper vegetative growth, they were exposed different treatments of lead for 14 days. The results showed the highest Pb concentration in the tailings of mine (1968 mg/kg) was more than 72-fold the global average and by increasing lead concentration, the growth factors decreased, but this reduction in growth was always greater in the non-metallicolous population, so that at the 200 mg/L treatment of lead, relative water content and shoot weight loss of the metallicolous population was 66.8 and 32.2%, respectively but they were 58.9 and 84.9% in non-metallicolous population in comparison with their control. With increasing the concentration of Pb in the medium, the accumulation of Pb in the roots and shoots of both populations are enhanced and lead accumulation was constantly more in the metallicolous population. The highest concentration levels of Pb were in the roots and shoots of the metallicolous population (15.2 and 0.9 mg per plant) which were 3.1- and 3.6-fold accumulation Pb in the non metallicolous population. The accumulation of lead in the roots was 15-folds more than the one in the shoots in both populations. The metallicolous population had an efficient antioxidant system which can grow with more accumulation of Pb and enhance the ratio of shoot to root, therefore, it can be used for phytoremediation.
کلیدواژهها [English]
A comparison of lead accumulation and growth factors of metallicolous and non- metallicolous populations of Marrubium cuneatum in hydroponic conditions
EXTENDED ABSTRACT
Heavy metal contamination is increasing with the enhancements in the exploitation of mines, industrial activities, sewage sludge and wastewaters, Pb-containing dyes, burning of solid and liquid waste and using pesticides and agricultural fertilizers. Phytoremediation is cost effective and efficient mechanisms for removing heavy metals from contaminated soils. The present study was devoted to investigate the concentration of lead (Pb) in the tailings around the Tang-e Douzan lead–zinc mine then determine the growth factors, relative water content and the lead accumulation of the metallicolous population (M) of Marrubium cuneatum (NM) collected from the vicinity of this mine in comparison with the non- metallicolous population.
To determine lead (Pb), soil and plant samples were collected from four different sites around plants (M. cuneatum) growing in the Tang-e Douzan mining area in this study and the concentration of types of lead (Pb), total, exchangeable and the water-soluble lead was determined by the use of acid digestion and different solvents. Seeds of M. cuneatum were collected around the Tang-e Douzan mine (M) and at Morghab spring (NM). The sterilized seeds were placed in 750 mg/L gibberellic acid solution for 24 hours and then exposed to 4 °C for 20 days for acceleration and synchronization of seed germination. Then they were sown on Perlite wetted with distilled water. The seedlings were grown in a greenhouse with a 16 h photoperiod (light intensity 200 μEm−2 s −1), day/night temperature of 25/20 °C, and regularly watered with one-fourth-strength modified Hoagland’s solution. After 45 days plants of uniform size of the both plant populations were transferred to hydroponic mediums and after proper vegetative growth, they were exposed to 0, 10, 50, 100, 200 mg/L treatments of lead for 14 days.
The results showed which Pb concentration in tailings around the mine was more than 72-fold the global average and by increasing lead concentration, the growth, relative water content of both populations significantly decreased, but this reduction in growth was always greater in the non-metallicolous population, so that at the 200 mg/L treatment, the fresh weight of shoots decreased to %84.9 and % 32.2, in the non-metallicolous and metallicolous population in comparison with their control, respectively. With increasing the concentration of Pb in the medium, the accumulation of Pb in the roots and shoots of both populations are enhanced and lead accumulation was constantly more in the metallicolous population. The accumulation of lead in the roots was more than 15-folds shoots in both populations. Translocation factor Pb did not significantly change in the metallicolous population with increasing Pb exposure.
It had an efficient antioxidant system which can grow with more accumulation Pb and ratio of shoot to root increased which is not apparent in one. Based on the potential of the metallicolous population grows in high lead-contaminated soils, it can be used for phytoremediation.