Costus speciosus (Koen ex. Retz.) Sm.: a suitable plant species for remediation of crude oil and mercury-contaminated soil.

The aim of this study was to evaluate the efficiency of Costus speciosus (Koen ex. Retz.) Sm. in the degradation of crude oil and reduction of mercury (Hg) from the contaminated soil in pot experiments in the net house for 180 days. C. speciosus was transplanted in soil containing 19150 mg kg-1 crude oil and 3.2 mg kg-1 Hg. The study includes the evaluation of plant biomass, height, root length, total petroleum hydrocarbon (TPH) degradation, and Hg reduction in soil, TPH, and Hg accumulation in plants grown in fertilized and unfertilized pots, chlorophyll production, and rhizospheric most probable number (MPN) at 60-day interval. The average biomass production and heights of C. speciosus in contaminated treatments were significantly (p < 0.05) lower compared to the unvegetated control. Plants grown in contaminated soil showed relatively reduced root surface area compared to the uncontaminated treatments. TPH degradation in planted fertilized, unplanted, and planted unfertilized pot was 63%, 0.8%, and 38%, respectively. However, compared to unvegetated treatments, TPH degradation was significantly higher (p < 0.05) in vegetated treatments. A comparison of fertilized and unfertilized soils showed that TPH accumulation in plant roots and shoots was relatively higher in fertilized soils. Hg degradation in soil was significantly (p < 0.05) more in planted treatment compared to unplanted treatments. The fertilized soil showed relatively more Hg degradation in soil and its accumulation in roots and shoots of plants in comparison to unfertilized soil. MPN in treatments with plants was significantly greater (p < 0.05) than without plants. The plant's ability to produce biomass, chlorophyll, break down crude oil, reduce Hg levels in soil, and accumulate TPH and Hg in roots and shoots of the plant all point to the possibility of using this plant to remove TPH and Hg from soil.

Field note: phytoremediation of petroleum sludge contaminated field using sedge species, Cyperus rotundus (Linn.) and Cyperus brevifolius (Rottb.) Hassk.

The aim of this study was to degrade total petroleum hydrocarbon (TPH) in a petroleum sludge contaminated site (initial TPH concentration of 65,000-75,000 mg kg(-1)) with two native sedge species namely Cyperus rotundus (Linn.) and Cyperus brevifolius (Rottb.) Hassk. Fertilized and unfertilized treatments were maintained separately to record the influence of fertilizer in TPH degradation. The average biomass production (twenty plants from each treatment) of C. rotundus was 345.5 g and that of C. brevifolius was 250.6 g in fertilized soil during 360 days. Decrease in soil TPH concentration was higher in fertilized soil (75% for C. rotundus and 64% for C. brevifolius) than in unfertilized soil (36% for C. rotundus and 32% for C. brevifolius). In unvegetated treatments, decrease in soil TPH concentration in fertilized (12%) and unfertilized soil (8%) can be attributed to natural attenuation and microbial degradation. TPH accumulation in roots and shoots was significantly higher in fertilized soil in comparison to unfertilized soils (p < 0.05). Most probable number (MPN) in planted treatments was significantly higher than in unplanted treatments (p < 0.05).

Phytoremediation of crude oil contaminated soil using nut grass, Cyperus rotundus.

The aim of this study was to evaluate the efficacy of Cyperus rotundus (nut grass), that could be effective in phytoremediation of crude oil contaminated soil. A net house experiment was conducted with different concentrations (2.05, 4.08, 6.1, 8.15 and 10.2%) of crude oil-contaminated soil for 180 days. Plant growth, biomass, total oil and grease (TOG) degradation and microbial numbers were analyzed at different intervals i.e. 60,120 and 180 days in different percentages of crude oil contaminated soil. In presence of crude oil, plant biomass and heights reduced up to 26 and 21.9% respectively. Concerning TOG content in soil, C. rotundus could decrease up to 50.01, 46.1, 42.6, 38.8 and 32.6% in treatment I, II, III, IV and V respectively in vegetated pots during 180 days. In case of unvegetated pots, the reductions of TOG were 4.4, 5.6, 6.6, 7.6 and 9.6% in treatment A, B, C, D and E respectively. However, there was significant degradation (P = 0.05) of TOG in vegetated pots in comparison to unvegetated pots thereby proving the efficacy of this plant species for use in phytoremediation.