Metal accumulation in a biological indicator (Ulva rigida) from the lagoon of Venice (Italy)

Abstract

Ulva rigida (C. Agardht) was collected from the Palude della Rosa (lagoon of Venice), a particular area characterized by a salinity gradient, from December 1991 to June 1993. Metal contents (Al, Mn, Fe, Cu, Zn, Cr, Co, Ni, Cd, and Pb) were determined by atomic absorption spectrophotometry and statistically analysed for differences between months and sampling sites. The mean seasonal variability is very significant (p < 0.001) for all studied metals. Seasonal trends are comparable for groups of metals according to possible functional similarities. A significant positive correlation was calculated for the pairs Fe-Al and Fe-Pb. Mechanisms regulating metal uptake are discussed, particularly the role of Fe and its linear relationship with Al. Metal concentrations in relation to salinity also were studied. Larger amounts of Fe, Zn, and Cd accumulated in correspondence of lower salinity, may be owing to both higher metal activity and burden of bioavailable metals in freshwater flowing into the Palude. Calculation of concentration factor (CF) indicates that U. rigida specifically accumulates Fe. CF linearly correlates with dissolved metal concentrations, suggesting that U. rigida is a good bioindicator of metal bioavailability, although seasonal active accumulation occurs in some cases (Mn). Metal concentrations determined in this macroalga support the conclusion that the studied area is rich in bioavailable Fe and poor in toxic metals. In any case, a great affinity for Al in U. rigida may be proposed.

The accumulation of metal (Co, Cr, Cu, Mn and Zn) in freshwater Ulva (Chlorophyta) and its habitat

“…Furthermore, the results from an experimental study indicated that Cu accumulation by U. reticulata at salinity of 20 psu was three times higher than that at 35 psu (Mamboya et al 2009). Similar results were published for two cosmopolitan Ulva species, where the accumulation of Zn and Cd in U. rigida and Cr and Zn in U. lactuca increased along with the decreasing salinity (Favero et al 1996). In the experimental studies it was observed that reducing the salinity of the medium increases the amount of Cu ions accumulated by Ulva reticulata thalli (Mamboya et al 2009).…”

Freshwater Ulva (Chlorophyta) as a bioaccumulator of selected heavy metals (Cd, Ni and Pb) and alkaline earth metals (Ca and Mg)

“…Also, for U. compressa from the Gulf of Aden, the order of metal concentrations was: Ni > Pb > Cd (Al-Shwafi and Rushdi, 2008). The order of heavy metal concentrations, for marine species such as U. rigida from the Lagoon Venice or U. compressa (Favero et al, 1996), correlated closely with the order observed for freshwater Ulva. Moreover, Cd had the lowest concentrations for both thalli from marine and freshwater Ulva species.…”

“…the following trend: Ni > Pb > Cd (Favero et al, 1996). Also, for U. compressa from the Gulf of Aden, the order of metal concentrations was: Ni > Pb > Cd (Al-Shwafi and Rushdi, 2008).…”

Harmful Elements in Estuarine and Coastal Systems

“…Bragato et al (2006) monitored growth dynamics, nutrient and heavy metal accumulation in the two dominating macrophytes Phragmites australis and Bolboschoenus maritimus, but they found that the heavy metal concentration in water and soil was not correlated to the plant content. Favero et al (1996) investigated the metal accumulation of Ulva rigida and reported that this specie specifically accumulates Fe. Caliceti et al (2002) measured the concentrations of heavy metals (Fe, Zn, Cu, Cd, Ni, Pb, Cr, As) in seven seaweeds of environmental and commercial relevance.…”