Giuseppe Bonanno

Trace element accumulation and distribution in the organs of Phragmites australis (common reed) and biomonitoring applications.

The concentrations of trace elements were studied in roots, rhizomes, stems, and leaves of Phragmites australis stands (common reeds), and in the corresponding samples of water and sediment from the mouth of the Imera Meridionale River (Sicily, Italy), an area affected by massive urbanization and intensive agriculture. The elements considered were Ag, Al, As, B, Ba, Be, Co, Fe, Mo, Pd, Pt, Rh, Sb, Se, Sr, Tl, and V. Concentrations in belowground organs were usually higher than aboveground tissues, and the general decreasing trend of element content was root>rhizome>leaf>stem. Trace element mobility was generally higher within the organs than in sediment to plant. Regarding Al, Fe, and V, the phytotoxic levels in roots and the low plant/root mobility, may indicate that roots are inherently tolerant to these metals, and act as filters to prevent toxic distribution in the plant. The high uptake of Pd and Rh showed that emissions of catalytic converters are one of the main health hazards of the study area. P. australis showed a direct response to the environmental conditions, and its application as a biomonitor should be considered.

Comparative performance of trace element bioaccumulation and biomonitoring in the plant species Typha domingensis, Phragmites australis and Arundo donax.

Toxic levels of trace elements in the environment have been reported worldwide over the last few decades, and their increasing concentrations are of the utmost concern because of the adverse effects on human life and ecosystems. Several plant species are able to accumulate trace elements, and may be used for monitoring and remediation of polluted sites. This study compared the capacity of trace element bioaccumulation in three wetland plants distributed worldwide: Typha domingensis, Phragmites australis and Arundo donax. The aims were to identify which species show better potential for removal and monitoring of these elements: Al, As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn. Results showed that all species may be used as biomonitors of trace element contamination in sediment, but only P. australis and A. donax showed also a correlation with water. Overall, T. domingensis and P. australis showed a greater capacity of bioaccumulation as well as a greater efficiency of element removal than A. donax. In particular, T. domingensis and P. australis may be used for Hg phytostabilization, the former acted also as a hyperaccumulator for Hg phytoextraction and as a promising species for As phytostabilization. In contaminated wetlands, the presence of T. domingensis and P. australis may increase the general retention of trace elements, thus, their introduction is recommended for possible actions of phytoremediation and biomonitoring.

Arundo donax as a potential biomonitor of trace element contamination in water and sediment

Environmental monitoring through living organisms is an effective technique of human impact assessment, based on reliable and cost-effective biological tools of control. In this study, roots, stems and leaves of the worldwide distributed macrophyte Arundo donax (giant reed) were tested as potential biomonitors of trace element contamination in water and sediment. In particular, the concentrations of the following elements were analyzed: Al, As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn. A two-year sampling was conducted in an urban watercourse of Catania (Sicily, Italy), affected by municipal and industrial discharges of wastewaters. Results showed that the amount of concentrations in plant tissues is significantly dependent on the kind of organ and element. Trace element concentrations decreased according to the pattern of root>leaf>stem, implying that roots acted as the main centers of bioaccumulation, and stems as transit organs as a consequence of the general high translocation from roots to leaves. Overall, A. donax showed a significant capacity of bioaccumulation in agreement with ecologically similar macrophytes. Positive correlations were found between trace concentrations in plant organs and sediment (Al, Cr, Mn, Ni, Zn), and water (Cu, Ni, Zn). The results of this study suggested that A. donax acts as an ecological indicator of environmental conditions, thus, its application may prove a useful tool during monitoring campaigns of wetlands.

Levels of heavy metals in wetland and marine vascular plants and their biomonitoring potential: A comparative assessment

The present study investigated the levels of As, Cd, Cr, Cu, Hg, Mn, Ni, Pb and Zn in the seagrasses Posidonia oceanica and Cymodocea nodosa, and in the wetland macrophytes Phragmites australis, Arundo donax, Typha domingensis, Apium nodiflorum, and Nasturtium officinale. Results showed that the bioaccumulation capacity from sediments, translocation, total levels in plant tissues, and bioindication of metals in sediments, are generally species-specific. In particular, the patterns of metals in the aquatic plants studied were overall independent of ecology (coasts vs wetlands), biomass, anatomy (rhizomatous vs non rhizomatous plants), and life form (hemicrytophytes vs hydrophytes). However, marine phanerogams and wetland macrophytes shared some characteristics such as high levels of heavy metals in their below-ground organs, similar capacity of element translocation in the rhizosphere, compartmentalization of metals in the different plant organs, and potential as bioindicators of Cu, Mn and Zn levels in the substratum. In particular, the present findings indicate that, despite ecological and morphological similarities, different plant species tend to respond differently to exposure to heavy metals. Furthermore, this seems to result from the species individual ability to accumulate and detoxify the various metals rather than being attributed to differences in their ecological and morpho-anatomical characteristics.

Heavy metal content in ash of energy crops growing in sewage-contaminated natural wetlands: potential applications in agriculture and forestry?

One of the greatest current challenges is to find cost-effective and eco-friendly solutions to the ever increasing needs of modern society. Some plant species are suitable for a multitude of biotechnological applications such as bioenergy production and phytoremediation. A sustainable practice is to use energy crops to clean up polluted lands or to treat wastewater in constructed wetlands without claiming further arable land for biofuel production. However, the disposal of combustion by-products may add significant costs to the whole process, especially when it deals with toxic waste. This study aimed to investigate the possibility of recycling ash from energy biomass as a fertilizer for agriculture and forestry. In particular, the concentrations of Cd, Cr, Cu, Mn, Pb and Zn were analyzed in the plant tissues and corresponding ash of the grasses Phragmites australis and Arundo donax, collected in an urban stream affected by domestic sewage. Results showed that the metal concentration in ash is 1.5-3 times as high as the values in plant tissues. However, metal enriched ash showed much lower element concentrations than the legal limits for ash reutilization in agriculture and forestry. This study found that biomass ash from constructed wetlands may be considered as a potential fertilizer rather than hazardous waste. Energy from biomass can be a really sustainable and clean option not only through the reduction of greenhouse gas emissions, but also through ash recycling for beneficial purposes, thus minimizing the negative impacts of disposal.

Application of two quality indices as monitoring and management tools of rivers. Case study: the Imera Meridionale river, Italy.

On the basis of the European Water Framework Directive (2000/60), the water resources of the member states of the European Community should reach good quality standards by 2015. Although such regulations illustrate the basic points for a comprehensive and effective policy of water monitoring and management, no practical tools are provided to face and solve the issues concerning freshwater ecosystems such as rivers. The Italian government has developed a set of regulations as adoption of the European Directive but failed to indicate feasible procedures for river monitoring and management. On a local scale, Sicilian authorities have implemented monitoring networks of watersheds, aiming at describing the general conditions of rivers. However, such monitoring programs have provided a relatively fragmentary picture of the ecological conditions of the rivers. In this study, the integrated use of environmental quality indices is proposed as a methodology able to provide a practical approach to river monitoring and management. As a case study, the Imera Meridionale River, Sicily’s largest river, was chosen. The water quality index developed by the U.S. National Sanitation Foundation and the floristic quality index based on the Wilhelm method were applied. The former enabled us to describe the water quality according to a spatial–temporal gradient, whereas the latter focused on the ecological quality of riparian vegetation. This study proposes a holistic view of river ecosystems by considering biotic and abiotic factors in agreement with the current European regulations. How the combined use of such indices can guide sustainable management efforts is also discussed.

Comparative analysis of element concentrations and translocation in three wetland congener plants: Typha domingensis, Typha latifolia and Typha angustifolia

This study analyzed the concentrations and distributions of Al, As, Cd, Cr, Cu, Hg, Mn, Ni, Pb and Zn in three different cattail species growing spontaneously in a natural wetland subject to municipal wastewater and metal contamination. The cattail species included Typha domingensis, T. latifolia and T. angustifolia. Results showed that all Typha species have similar element concentrations in roots, rhizomes and leaves, and similar element mobility from sediments to roots and from roots to leaves. This study corroborated three patterns of Typha species growing in metal contaminated environments: high tolerance to toxic conditions, bulk element concentrations in roots, and restricted element translocation from roots to leaves. This study showed that three different Typha species respond similarly to metal inputs under the same polluting field conditions. Given their similar metal content and similar biomass size, our results suggest that T. domingensis, T. latifolia and T. angustifolia may have comparable capacity of phytoremediation. High element uptake and large biomass make Typha species some of the best species for phytoremediation of metal contaminated environments.

Ricinus communis as an Element Biomonitor of Atmospheric Pollution in Urban Areas

Leaves and fruits of Ricinus communis (castor oil plant) were studied as potential biomonitors of atmospheric pollution in urban areas. The concentrations of Al, As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn were analyzed in samples collected in the city of Catania (Italy) and compared with a pristine area. This study showed that the fruits of R. communis act as better biomonitors of element concentrations in the atmosphere as compared to the leaves. In particular, this pattern was evident for Cu, Pb, and Zn, typical atmospheric pollutants. Fruits proved especially sensitive to Pb accumulation; thus, all products derived from them, such as castor oil and biofuels, should be obtained in places where the exposure to Pb is low to avoid potential contamination. The plant R. communis seems a promising species as a biomonitor of atmospheric pollution, and given its wide distribution, may be used for large-scale networks of biomonitoring.

Trace elements in Mediterranean seagrasses and macroalgae. A review

This review investigates the current state of knowledge on the levels of the main essential and non-essential trace elements in Mediterranean vascular plants and macroalgae. The research focuses also on the so far known effects of high element concentrations on these marine organisms. The possible use of plants and algae as bioindicators of marine pollution is discussed as well. The presence of trace elements is overall well known in all five Mediterranean vascular plants, whereas current studies investigated element concentrations in only c. 5.0% of all native Mediterranean macroalgae. Although seagrasses and macroalgae can generally accumulate and tolerate high concentrations of trace elements, phytotoxic levels are still not clearly identified for both groups of organisms. Moreover, although the high accumulation of trace elements in seagrasses and macroalgae is considered as a significant risk for the associated food webs, the real magnitude of this risk has not been adequately investigated yet. The current research provides enough scientific evidence that seagrasses and macroalgae may act as effective bioindicators, especially the former for trace elements in sediments, and the latter in seawater. The combined use of seagrasses and macroalgae as bioindicators still lacks validated protocols, whose application should be strongly encouraged to biomonitor exhaustively the presence of trace elements in the abiotic and biotic components of coastal ecosystems.

Trace element biomonitoring using mosses in urban areas affected by mud volcanoes around Mt. Etna. The case of the Salinelle, Italy.

Trace element impact was assessed using mosses in a densely inhabited area affected by mud volcanoes. Such volcanoes, locally called Salinelle, are phenomena that occur around Mt. Etna (Sicily, Italy) and are interpreted as the surface outflow of a hydrothermal system located below Mt. Etna, releasing sedimentary fluids (hydrocarbons and NaCl brines) along with magmatic gases (mainly CO2 and He). To date, scarce data are available about the presence of trace elements, and no biomonitoring campaigns are reported about the cumulative effects of such emissions. In this study, concentrations of Al, As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, V, and Zn were detected in the moss Bryum argenteum, in soil and water. Results showed that the trace element contribution of the Salinelle to the general pollution was significant for Al, Mn, Ni, and Zn. The comparison of trace concentrations in mosses from Salinelle and Etna showed that the mud volcanoes release a greater amount of Al and Mn, whereas similar values of Ni were found. Natural emissions of trace elements could be hazardous in human settlements, in particular, the Salinelle seem to play an important role in environmental pollution.