Utilization of the seagrass Posidonia oceanica to evaluate the spatial dispersion of metal contamination

Our plain-English summary of Utilization of the seagrass Posidonia oceanica to evaluate the spatial dispersion of metal contamination, by C. Lafabrie, G. Pergent, C. Pergent-Martini (The Science of the Total Environment, 2009).

The study

• Authors: C. Lafabrie, G. Pergent, C. Pergent-Martini
• Journal: The Science of the Total Environment
• Published: 2009;407(7):2440-6
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Metal concentrations have been measured in blades of the endemic Mediterranean seagrass Posidonia oceanica, along transects from three different contaminant point sources (the former asbestos mine of Canari - Corsica, France; the chemical plant of Solvay/Rosignano - Livorno, Italy; and the industrial harbour of Porto-Torres - Sardinia, Italy). The aim of this study was to evaluate the spatial extent of the impact of these sources in terms of metal contamination. The results showed that metal contamination from the former mine of Canari (cobalt - Co, chromium - Cr and nickel - Ni) extends at least 5 km to the north and south. The impact of this mine, which closed in 1965, seems to be lingering still. Mercury (Hg) contamination in the Livorno location was difficult to evaluate due to the presence of others potential sources of mercury in the area (e.g. industrialized city of Livorno, natural cinnabar deposits, intense tectonic activity of the area). At any rate, mercury concentration decreased strongly with distance from the plant. Lead (Pb) contamination at the Porto-Torres harbour was very low and disappeared with distance from the harbour. However, as the Porto-Torres harbour does not appear as a substantial point source of Pb contamination and because of the ubiquitous characteristic of the Pb element, it is difficult to draw any general conclusions concerning this element. The results presented in this study demonstrated the usefulness of the seagrass P. oceanica as a tool for the evaluation of the spatial extent of metal contaminations from point sources and could, therefore, contribute to on-going efforts to manage coastal environments.

In plain English

This was an environmental field study, not a study of human health or asbestos fibers. The authors measured cobalt, chromium, nickel, mercury and lead in leaf blades of the Mediterranean seagrass Posidonia oceanica at 12 sites along transects from three pollution sources: a former asbestos mine at Canari, Corsica, closed in 1965; a chemical plant at Rosignano near Livorno, Italy; and the industrial harbour of Porto-Torres, Sardinia. Samples were collected in summer 2004 or 2005. Near the mine, cobalt, chromium and nickel were highest at a site south of the mine rather than directly in front of it, and decreased with distance on both sides. Cobalt and nickel at the transect ends stayed above the lowest levels reported elsewhere. Mercury was highest nearest the Rosignano plant and fell with distance, but other mercury sources made the plant's share hard to judge. Lead at Porto-Torres was low. The authors concluded that the mine's impact seems to linger, extending at least 5 km north and south. They also concluded that the seagrass is a useful tool for mapping some metal contamination, though sampling sites were few.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Environmental field study (short communication) measuring metal concentrations in seagrass along transects from three point sources
• Who was studied: Leaf blades of the seagrass Posidonia oceanica at 12 sites in the north-western Mediterranean: 5 at Canari (Corsica, France), 3 at Livorno (Tuscany, Italy), 4 at Porto-Torres (Sardinia, Italy). At each site, 21 shoots were collected by divers at about 10 m depth and pooled into three replicates of 7 shoots. Samples were taken in summer 2004 at Canari and Porto-Torres and in summer 2005 at Livorno.
• Exposure: Metals (cobalt, chromium, nickel, mercury, lead) from three point sources: a former asbestos mine at Canari, a chlor-alkali chemical plant at Rosignano, and an industrial harbour at Porto-Torres. Asbestos fibers themselves were not measured. Citing earlier work, the article states the mine discharged serpentinite rubble into the sea from 1948 to 1965.
• Main results:
  • At Canari, the highest cobalt, chromium and nickel concentrations were at site C2, south of the mine (site C3 is directly in front of it). Values at C2 were cobalt 14.4 plus or minus 1.4, chromium 1.2 plus or minus 0.1, and nickel 128.3 plus or minus 13.9 micrograms per gram dry weight. Concentrations decreased with distance on both sides of C2.
  • At Canari, cobalt differed between sites C2 and C4 (P=0.040) and between C2 and C5 (P=0.081). The authors tested at both the 0.05 and 0.10 levels.
  • At Canari, nickel differed between sites C2 and C4 (P=0.047) and between C2 and C5 (P=0.035).
  • At Canari, chromium differed between sites C2 and C5 (P=0.019).
  • At Canari, cobalt and nickel at both ends of the transect had not fallen to background levels, judged against the lowest values reported in the literature for this seagrass.
  • At Canari, chromium at the transect ends fell towards background levels.
  • The authors interpreted the Canari results as showing the former mine's impact seems to linger, with metal contamination extending at least 5 km north and south of the mine.
  • At Livorno, mercury was highest at site L1, nearest the chemical plant, at 0.21 plus or minus 0.00 micrograms per gram dry weight. It decreased with distance.
  • At Livorno, mercury differed between sites L1 and L3 (P=0.051).
  • At Porto-Torres, lead was highest at site P2, at 2.7 plus or minus 0.3 micrograms per gram dry weight, with a difference between sites P2 and P3 (P=0.047). The authors described lead contamination there as very low.
• The authors' conclusion: The authors concluded that, despite some difficulties and a small number of sampling sites, the seagrass Posidonia oceanica is a useful tool for evaluating the spatial extent of some metal contamination from point sources.
• Limitations the authors state:
  • The number of sampling sites along each transect was small.
  • Other possible mercury sources in the Livorno-Rosignano area (the industrial city of Livorno, natural cinnabar deposits, tectonic activity) made it difficult to attribute mercury contamination solely to the plant.
  • At Porto-Torres the transect could only be placed north-west of the harbour, because no seagrass was found to the east. The authors said general conclusions about lead could not be drawn.

Topics

Medical terms in this study, explained in our Lexicon: Endemic.

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