Clean water is a rapidly diminishing resource on our planet, which is major problem since we depend on it for survival. As a result of our rapidly growing population, the types and amounts of contaminants that we put into the aquatic environment are staggering – from heavy metals and fertilizers to pesticides, pharmaceuticals, and personal care products. The need for economically feasible and efficient methods of water remediation is critical as these contaminants can cause a myriad of health problems, not only in humans, but organisms that make up our entire food chain. Phytoremediation, the use of plants to remove contaminants from the environment, is an emerging technology with amazing potential. (Alkorta et al. 2004)
Azolla, an aquatic floating fern, (Fig. 1) is one of the many plant species with the ability to hyperaccumulate contaminants from its environment, making it an ideal candidate for phytoremediation systems (Sood et al. 2012). There are three species native to the United States: Azolla filiculoides, A. mexicana, and A. caroliniana (Fig. 2). Gaining a better understanding of what contaminants the ferns can remediate and how they are affected by certain contaminants will ultimately lead to these plants being used successfully in remediation sites.
Figure 1. Azolla caroliniana
Research conducted on Azolla here at DWFI is two-fold.
First, we expand on how the fern remediates the heavy metal lead from solution and investigate how the fern and its cyanobacteria symbiont are impacted by Pb sequestration (Fig. 3). A series of bench scale tests have been performed testing differences in Pb accumulation under different conditions as well as by different species. A paper on some of the current results from some of our studies is currenly under review at the moment, and we will be excited to share, pending successful submission!
Figure 2. Geographical distribution in North America of A. A. caroliniana, B. A. mexicana, and C. A. filiculoides. Maps were generated by USDA PLANTS (2012). Colored sections represents presence or absence of the species recorded in at least one location within each state or province.
Second, multiple studies are being conducted on the use of Azolla for the remediation of emerging organic contaminants – pharmaceuticals and personal care products (PPCPs). A variety of analytical approaches are being engaged to measure the removal of SDS, ibuprofen, fluoxetine, and 17b-estradiol from aqueous solution by Azolla.
Figure 3. A simplified diagram of metal sequestration in a terrestrial plant.
Azolla has been shown to be successful at remediating contaminants from both industrial waste sites as well as wastewater (Bharti and Banerjee, 2012; Rai 2007), two major sources of environmental contamination. The research happening here at DFWI with Azolla will expand on its capabilities and suggests ways in which to achieve the highest level of remediation of select contaminants. Numerous sites, including mine effluents, agricultural lagoons, and settling pools at wastewater treatment plants would be ideal for remediation by Azolla. It is our hope that the research happening here will aid in the future of cleaner water.
Alkorta, I., Hernández-Allica, J., Becerril, J. M., Amezaga, I., Albizu, I., & Garbisu, C. (2004). Recent findings on the phytoremediation of soils contaminated with environmentally toxic heavy metals and metalloids such as zinc, cadmium, lead, and arsenic. Reviews in Environmental Science and Biotechnology, 3(1), 71-90.
Bharti, S., & Kumar Banerjee, T. (2012). Phytoremediation of the coalmine effluent. Ecotoxicology and environmental safety, 81, 36-42.
Rai, P. K. (2007). Wastewater management through biomass of Azolla pinnata: An eco-sustainable approach. AMBIO: A Journal of the Human Environment, 36(5), 426-428.
Sood, A., Uniyal, P. L., Prasanna, R., & Ahluwalia, A. S. (2012). Phytoremediation potential of aquatic macrophyte, Azolla. Ambio, 41(2), 122-137.