BACKGROUND, AIMS AND SCOPE: Research and development has its own benefits and inconveniences. One of the inconveniences is the generation of enormous quantity of diverse toxic and hazardous wastes and its eventual contamination to soil and groundwater resources. Ethidium bromide (EtBr) is one of the commonly used substances in molecular biology experiments. It is highly mutagenic and moderately toxic substance used in DNA-staining during electrophoresis. Interest in phytoremediation as a method to solve chemical contamination has been growing rapidly in recent years. The technology has been utilized to clean up soil and groundwater from heavy metals and other toxic organic compounds in many countries like the United States, Russia, and most of European countries. Phytoremediation requires somewhat limited resources and very useful in treating wide variety of environmental contaminants. This study aimed to assess the potential of selected tropical plants as phytoremediators of EtBr. MATERIALS AND METHODS: This study used tomato (Solanum lycopersicum), mustard (Brassica alba), vetivergrass (Vetiveria zizanioedes), cogongrass (Imperata cylindrica), carabaograss (Paspalum conjugatum), and talahib (Saccharum spontaneum) to remove EtBr from laboratory wastes. The six tropical plants were planted in individual plastic bags containing soil and 10% EtBr-stained agarose gel. The plants were allowed to establish and grow in soil for 30 days. Ethidium bromide content of the test plants and the soil were analyzed before and after soil treatment. Ethidium bromide contents of the plants and soils were analyzed using an UV VIS spectrophotometer. RESULTS: Results showed a highly significant (p≤0.001) difference in the ability of the tropical plants to absorb EtBr from soils. Mustard registered the highest absorption of EtBr (1.4±0.12 μg kg⁻¹) followed by tomato and vetivergrass with average uptake of 1.0±0.23 and 0.7±0.17 μg kg⁻¹ EtBr, respectively. Cogongrass, talahib, and carabaograss had the least amount of EtBr absorbed (0.2±0.6 μg kg⁻¹). Ethidium bromide content of soil planted to mustard was reduced by 10.7%. This was followed by tomato with an average reduction of 8.1%. Only 5.6% reduction was obtained from soils planted to vetivergrass. Soils planted to cogongrass, talahib, and carabaograss had the least reduction of 1.52% from its initial EtBr content. DISCUSSION: In this study, mustard, tomato, and vetivergrass have shown their ability to absorb EtBr from contaminated soil keeping them from expanding their reach into the environment and preventing further contamination. Its downside, however, is that living creatures including humans, fish, and birds, must be prevented from eating the plants that utilized these substances. Nonetheless, it is still easier to isolate, cut down, and remove plants growing on the surface of the contaminated matrices, than to use strong acids and permanganates to chemically neutralize a dangerous process that can further contaminate the environment and pose additional risks to humans. Though this alternative method does not totally eliminate eventual environmental contamination, it is by far produces extremely insignificant amount of by-products compared with the existing processes and technologies. CONCLUSIONS: Mustard had the highest potential as phytoremediator of EtBr in soil. However, the absorption capabilities of the other test plants may also be considered in terms of period of maturity and productivity. RECOMMENDATIONS AND PERSPECTIVES: It is recommended that a more detailed and complete investigation of the phytoremediation properties of the different plants tested should be conducted in actual field experiments. Plants should be exposed until they reach maturity to establish their maximum response to the toxicity and mutagenecity of EtBr and their maximum absorbing capabilities. Different plant parts should be analyzed individually to determine the movement and translocation of EtBr from soil to the tissues of plants. Since this study has established that some plants can thrive and dwell in EtBr-treated soil, an increased amount of EtBr application should be explored in future studies. It is suggested therefore that a larger, more comprehensive exploration of phytoremediation application in the management of toxic and hazardous wastes emanating from biotechnology research activities should be considered especially on the use of vetivergrass, a very promising tropical perennial grass.

Proliferation of fly ash (FA) deposits and its toxicity have become a global concern, which contaminate the ecosystems of our Earth. In this regard, identification of potential plant species for FA deposits’ restoration is the main concern. Keeping this view in mind, the present study was conducted to identify potential plant species naturally growing on FA deposits for the restoration purposes. Six intensive surveys were made during 2010–2014 to collect naturally growing plant species during different seasons from two FA deposits in Unchahar of Raebareli district, Uttar Pradesh, India. The plant species having potential for FA deposits’ restoration were identified on the basis of their ecological importance, dominance at the study sites and socio-economic importance for rural livelihoods. Typha latifolia L., Cynodon dactylon (L.) Pers., Saccharum spontaneum L., Saccharum bengalense Retz. (syn. Saccharum munja), Prosopis juliflora (Sw.) DC., Ipomoea carnea Jacq. and Acacia nelotica L. are identified as potential plant species for FA deposits’ restoration. Furthermore, the characteristics of naturally colonized species can be used for the phytorestoration during a revegetation plan of new FA deposits for multiple benefits.

Two examples of the creation of naturalized areas in the littoral zone of the Three Gorges Reservoir in the urban core of Chongqing City, China, are described. The areas were created for the purpose of restoring ecological functions and services. Plants were selected based on surveys of natural wetland vegetation in the region, and experiments were conducted to discover the capacity of species of interest to survive the sometimes extreme hydrological regimes at the sites. Novel methods were developed to stabilize the plants against the rigors of extreme summer floods and constant swash, notably zigzag berms of rocks wrapped in iron mesh. The areas include native reeds, grasses, shrubs, and trees. Plant communities in the areas are zoned according to flooding stress, and their structure is less stable at lower elevations that are subjected to greater stress. The tall grass Saccharum spontaneum (widespread in Southern Asia) and the tree Pterocarya stenoptera (native to Southwest China) are notable for their utility at these sites in the center of a large city. Communities of tall reeds and grasses have become so dense and stable that they now provide the ecosystem services of capturing river sediments and resisting erosion of the river banks. It is recommended that extensive greening of the riparian zones in urban areas of the Three Gorges Reservoir be conducted for the purpose of providing ecosystem services, based in part on the experiences described here.