A Review of the Performance of Woody and Herbaceous Ornamental Plants for Phytoremediation in Urban Areas
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Review Article ii FF o o r r e e s s t t doi: 10.3832/ifor3242-013 Biogeosciences and Forestry vol. 13, pp. 139-151 A review of the performance of woody and herbaceous ornamental plants for phytoremediation in urban areas Maurizio Capuana Urban and periurban areas are often contaminated by several pollutants. Phy- toremediation is considered to be an effective and eco-friendly strategy for the restoration of these contaminated lands. For this purpose, the exploitation of ornamental plants could be an additional option, due to their positive im- pact on the landscape. In this paper, we reviewed a selection of species which have been proposed for utilization in phytoremediation. Several tree species have been introduced in the past into urban environments for parks, gardens and avenues, with a selection studied for their capacity to absorb, tolerate, and translocate contaminants. Shrubby and herbaceous species are also com- monly exploited for their ornamental features and are now studied for phy- toremediation purposes. The responses of several effective species to the presence of heavy metals or dangerous organic compounds in the growth sub- strate are examined in this paper. Keywords: Environment, Heavy Metals, Landscape, Organics, Pollution Introduction lead is commonly found near roads and as- hold or translocate specific contaminants; Environmental pollution is an increasing sociated with zinc and cadmium (Garcia & moreover, these ornamentals pose little global problem. Contaminants vary de- Millan 1998); excessive copper is frequent- threat to food chain contamination, and pending upon their source and the type of ly detected in soils used for a long period can be appreciated by the resident popula- ecosystem involved. Urban areas can be af- as agricultural land, especially vineyards tions for their positive impact on land- fected by several organic and inorganic (Bretzel & Calderisi 2006), and chromium is scape. contaminants, which negatively impact a residual of some industrial activities (Za- In the more circumscribed field of flower- soils, water and the atmosphere (Biasioli et yad & Terry 2003). Organic pollutants can beds and urban green plantations, special al. 2006). The study of the effect of con- also injure urban soils by direct contamina- mixtures of topsoil are commonly used and tamination by pollutants on these urban tion, or after initial emission into the at- rules have to be followed with regards to environments and potential solutions to mosphere followed by transport in both the presence of contaminants (Huinink the problems associated with soil contami- gaseous and particulate forms, and subse- 1998). Risks are higher in allotments, since nation and rehabilitation dates to the last quent accumulation in soils after dry and contaminants could be transferred to the few decades (Tiller 1992). wet atmospheric deposition (Cachada et al. food chain (Scheyer 2000, Khalid et al. Urban and periurban soils are often pol- 2012). Urban soils may also be very differ- 2017). Attention has to be paid to parks, luted as consequence of human activities. ent to more natural soils, due to lower or- playgrounds, kindergartens and urban ar- Brownfield sites, mainly located in periur- ganic fraction, water drainage and aera- eas where people come into close contact ban sites, reflect industrial heritage and are tion, different pH value, microorganism with soil (Abrahams 2002, Chiesura 2004, probably the most common scenarios content and the presence of anthropic ma- De Miguel et al. 2006, Lee et al. 2006, Ljung where urban and periurban contaminated terial. These features can change the per- et al. 2006a, Ljung et al. 2006b). In these soils are found (Sleegers 2010). In general, formance of these soils with respect to pol- areas, selected ornamental plants may play heavy metals are the major contaminants: lutants (Tiller 1992, Schleu et al. 1998). As an important role in reducing the presence stated by Cunningham & Berti (1993) “new of pollutants, while at the same time giving technologies are needed to address nu- a pleasant temporary decoration. Botanists Institute of Biosciences and Bioresources, merous contaminants, especially those have elaborated several definitions of or- National Research Council, v. Madonna del Pi- that are neither volatile nor mobile in soil namental plants; these can be defined as ano 10, I-50019 Sesto Fiorentino, FI (Italy) solution”. Plants have been proposed to plants that have highly ornamental fea- mitigate the dangerous effects of pollu- tures such as ornamental flowers, fruits or @ Maurizio Capuana tants, with phytoremediation recognized foliage (Li & Zhou 2005). Nevertheless, we ([email protected]) as a promising technology for the recovery must also consider that the ornamental of contaminated environments (Salt et al. value of a plant may vary according to the Received: Sep 18, 2019 - Accepted: Feb 07, 1995). Phytoremediation could be success- different tastes and traditions of each 2020 fully exploited in urban territories; in these country. contexts, many herbaceous and some The focus of our attention is the “origi- Citation: Capuana M (2020). A review of the woody species (including forest species) nal” soils, and the present article is aimed performance of woody and herbaceous are suitable for planting because of their primarily at suburban areas, which can be ornamental plants for phytoremediation in ornamental features and adaptability to in- even heavily contaminated, due to their urban areas. iForest 13: 139-151. – doi: habited areas. Furthermore, plants are use- past uses. If the plants chosen to be used 10.3832/ifor3242-013 [online 2020-04-14] ful sensors to identify environmental con- in remediation are tree species, several se- tamination and potential exposures to pol- lection criteria have to be taken into ac- Communicated by: Werther Guidi Nissim lutants (Henry et al. 2013). In fact, some of count (Conway & Vander Vecht 2015), in- these species show the capacity to absorb, cluding problems linked to climate change © SISEF https://iforest.sisef.org/ 139 iForest 13: 139-151 Capuana M - iForest 13: 139-151 y r t Fig. 1 - In vitro culture for s e the rapid mass propaga- r tion of plants to be o F exploited in phytoremedia- d tion: (a) multiclonal culture n a of Populus alba; (b) in vitro- s rooted plantlet of Salix e c alba. n e i c s o e g o i B – t s e r o F i (Roloff et al. 2009, Killi et al. 2018) and the plants (woody and herbaceous) must be Several tree species have been success- preferences expressed by the resident harvested and treated, since the content fully used in urban parks, gardens and av- populations (these inclinations are gener- of pollutants is an important concern. Sev- enues; for instance, in Europe pines, cy- ally for plantations with high level of biodi- eral solutions are available for this pur- presses, poplars, willows, birches, syca- versity – Carrus et al. 2015). Also, it is al- pose, including compacting, composting, mores and lindens are widely planted (Mil- ways advisable to consider all of the ac- biogas production and pyrolysis (Blaylock ler et al. 2015). Numerous recent studies tions related to the sustainability of planta- & Huang 2000, Nanda Kumar et al. 1995, demonstrated that some tree species have tions (Ferrini & Fini 2011) and the analysis of Garbisu & Alkorta 2001). The easiest proce- a good attitude to tolerate, absorb and re- costs for their periodic removal and dis- dure is incineration of biomass, with recov- move specific contaminants from the soil posal (Berndes et al. 2004, Lewandowski et ery of residual heavy metals. When orna- (reviewed by Mahar et al. 2016, Pajević et al. 2006, Compernolle et al. 2012, Saxena et mental flowers are used, cut flowers with al. 2016). Trees can enhance the aesthetic al. 2019, Wan et al. 2016). limited contaminants content can be even- quality of urban landscape (Chen et al. In this context, we might also consider tually sold. 2009), simultaneously providing other the possible use of tree planting for short- An overview is provided of the most ef- functions, such as improved air quality rotation coppicing, by which a profitable fective woody and herbaceous plants (tree (Mukherjee & Agrawal 2018), reduction of recovery of the used plants can be per- species, shrubs and herbaceous flowers) noise pollution (Pathak et al. 2011), mitiga- formed. For instance, willows may be ex- for the remediation of urban and suburban tion of waterlogging (Livesley et al. 2016) ploited for this purpose, since these spe- areas, through analysis of recent literature and reducing heat island effects (Scholz et cies display high ornamental value and are illustrating how these species react when al. 2018 – Fig. 1, Fig. 2). suitable for bioenergy production com- facing either inorganic (heavy metals) or A great variety of herbaceous and bined with potential for phytoremediation organic contaminants. This review is specif- shrubby species have been analysed for (Guidi et al. 2013, Guidi Nissim et al. 2014b). ically addressed to a selection of species phytoremediation purposes (reviewed by Therefore, the choice of species to be used suitable for exploitation in urban environ- Liu et al. 2018 – Fig. 3), but many still re- for phytoremediation includes considera- ments, due to their adaptability, ornamen- main to be studied. Furthermore, plants’ tion of criteria such as respect for biodiver- tal characteristics and appreciation by resi- association, with its huge possibilities of sity, easy harvesting management, by- dent populations; the proposed selection, combinations, offers interesting perspec- product utilisation and possible economic albeit large, is mainly focused on the spe- tives and is therefore discussed. returns. cies best suited to European and American The choice of ornamental woody and After their use for soil remediation, all environments. herbaceous plants for urban (and periur- Fig. 2 - Woody species for phytoremediation: (a) a poplar plantation in an urban site (outskirts of Flo- rence); (b) Betula pendula. 140 iForest 13: 139-151 Phytoremediation in urban areas y r Fig.