Effect of Organic Manures on the Growth of Cymbopogon citratus and Chrysopogon zizanioides for the Phytoremediation of Chromite-Asbestos Mine Waste: A Pot Scale Experiment

Our plain-English summary of Effect of Organic Manures on the Growth of Cymbopogon citratus and Chrysopogon zizanioides for the Phytoremediation of Chromite-Asbestos Mine Waste: A Pot Scale Experiment, by A. Kumar, S.K. Maiti (International Journal of Phytoremediation, 2015).

The study

• Authors: A. Kumar, S.K. Maiti
• Journal: International Journal of Phytoremediation
• Published: 2015;17(1-6):437-47
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The abandoned chromite-asbestos mines are located in the Roro hills, West Singhbhum, Jharkhand, India, where mining operation ceased in 1983, and since then these mines are causing environmental pollution. The present study was planned to phytoremediate these metalloid and metal contaminated mine waste by using two aromatic grasses, Cymbopogon citratus and Chrysopogon zizanioides by applying different proportions of amendments (chicken manure, farmyard manure and garden soil). Mine waste has neutral pH, low electrical conductivity and organic carbon with higher concentration of total metals (Cr and Ni) as compared to soil. Application of manures resulted significant improvements of mine waste characteristics and plant growth, reduction in the availability of total extractable toxic metals (Cr, Ni) and increase in Mn, Zn and Cu concentration in the substrate. The maximum growth and biomass production for C. citratus and C. zizanioides were found in T-IV combination comprising of mine waste (90%), chicken manure (2.5%), farmyard manure (2.5%) and garden soil (5%). Addition of T-IV combination also resulted in low Cr and Ni accumulation in roots and reduction in translocation to shoots. Study indicates that C. citratus and C. zizanioides can be used for phytostabilization of abandoned chromite-asbestos mine waste with amendments.

In plain English

This pot experiment studied plants, not people. Waste came from abandoned chromite-asbestos mines in Jharkhand, India, closed in 1983. From August 2012, they grew two grasses, Cymbopogon citratus and Chrysopogon zizanioides, for about five months. Waste was used alone or in four mixtures, two with chicken and farmyard manure and two also with garden soil, in three pots per treatment per grass. The waste had high total chromium (2555 mg/kg) and nickel (1160 mg/kg); only 0.07% of the chromium and 0.038% of the nickel was plant available. Manure raised organic carbon and nutrients. A mix of 90% waste, 2.5% chicken manure, 2.5% farmyard manure and 5% garden soil gave the most growth. C. citratus grew more than C. zizanioides in every treatment. Plants on unamended waste showed dead and yellowed tissue. Amendment lowered shoot chromium and nickel, the authors reported, though plant-available chromium and nickel were higher in the mixtures than in unamended waste. The authors concluded that both grasses can be used to stabilize this waste when it is amended. Asbestos fibers and health outcomes were not measured.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Open-pot plant growth experiment (randomized block design, three replicates per treatment and plant type); not a study of people
• Who was studied: Mine waste from the foothills of the abandoned chromite-asbestos mines of the Roro hills, Chaibasa, West Singhbhum, Jharkhand, India (mining ceased 1983). Two grasses, Cymbopogon citratus and Chrysopogon zizanioides, were transplanted into pots in August 2012 and grown for about 5 months.
• Exposure: Grasses were grown in 100% mine waste (control) or in amended waste. The treatments were T-I (95% waste, 2.5% chicken manure, 2.5% farmyard manure), T-II (90%, 5%, 5%), T-III (95%, 1.25%, 1.25%, 2.5% garden soil) and T-IV (90%, 2.5%, 2.5%, 5% garden soil). Metals measured were Cr, Ni, Mn, Zn, Co, Cu, Pb and Cd. No asbestos fiber type or fiber content was reported.
• Main results:
  • Unamended mine waste had total Cr of 2555 mg/kg and total Ni of 1160 mg/kg. Of the total Cr, 0.07% was plant available; of the total Ni, 0.038% was plant available.
  • Amendments increased organic carbon from 0.11% in unamended waste to 1.96% in the T-II treatment
  • Manures and garden soil reduced total Cr and Ni in the substrate (total Cr 2554.58 mg/kg in control vs 2330.66 mg/kg in T-IV; Table 4), while Mn, Zn, Cu and Pb increased
  • Plant-available (DTPA-extractable) metals were higher in the mixtures than in unamended waste. Per Table 4, Cr was 1.79 mg/kg in the control vs 1.98 mg/kg in T-IV, and Ni was 0.45 vs 0.59 mg/kg. The authors attributed the Ni increase to the manures.
  • The T-IV mixture produced more biomass than any other treatment for the grasses
  • Biomass was low in T-II, the treatment with the most manure
  • C. citratus had higher total biomass than C. zizanioides in all treatments
  • Both grasses grown on unamended waste showed necrosis and chlorosis
  • In C. citratus, T-IV gave high biomass with low metal accumulation in roots and shoots. The authors reported that Cr and Ni in shoots fell after amendment.
• The authors' conclusion: The authors concluded that C. citratus and C. zizanioides can be used for phytostabilization of the chromite-asbestos mine waste with amendments. They called the two grasses, in their words, 'excellent grass species' for phytoremediation of this waste.

Topics

Medical terms in this study, explained in our Lexicon: Translocation.

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