Detecting and characterising sources of persistent organic pollutants (PAHs and PCBs) in surface sediments of an industrialized area (harbour of Trieste, northern Adriatic Sea)

In the period 1957-77 a part of 100-200 tons of mercury as industrial waste was discharged into a 10 km2 lagoon (“Pialassa Baiona”) connected to the Ravenna harbor and the Northern Adriatic Sea (Italy). Extremely high levels of Hg (up to 160 µg/g) were found in surface sediments, but the maximum values (up to 1114 µg/g) were detected in subsurface layers, down to 80 cm, close to the industrial source, and values of 1-2 µg/g were recorded in the fore-harbor, outside the lagoon. The calculation of total Hg budget in sediments gave 38 tons of Hg being stored within a contaminated area of 15 km2. The redistribution of polluted sediments would seem to be due mainly to the tidal action; more than 80% of the total Hg discharged is confined in 10% of the area, i.e. in the southern ponds close to the input point. The time necessary for a restoration of the area was estimated by using different approaches of accumulation rate calculations (210Pb, Hg peak). It appears that 40-50 years would be needed to clean the surface sediments of the Ravenna lagoon from the mercury contamination. We suggest that remedial plans should be focused on the southern ponds.

Download Full-text

Trends of Nitrogen and Phosphorus in Surface Sediments of the Lagoons of the Northern Adriatic Sea as a Study Case

Water ◽

10.3390/w13202914 ◽

2021 ◽

Vol 13 (20) ◽

pp. 2914

Author(s):

Adriano Sfriso ◽

Alessandro Buosi ◽

Yari Tomio ◽

Abdul-Salam Juhmani ◽

Michele Mistri ◽

...

Keyword(s):

Surface Sediments ◽

Adriatic Sea ◽

Organic Phosphorus ◽

Anthropogenic Impacts ◽

Venice Lagoon ◽

Nutrient Concentrations ◽

Nitrogen And Phosphorus ◽

Northern Adriatic Sea ◽

Northern Adriatic ◽

Po Delta

The analysis of nutrient concentrations in surface sediments is a reliable tool for assessing the trophic status of a water body. Nitrogen and phosphorus concentrations are strongly related to the sediment characteristics but are mainly driven by anthropogenic impacts. The results of the determination of total nitrogen and total inorganic and organic phosphorus in surface sediments of the lagoons and ponds of the northwestern Adriatic Sea (Marano-Grado, Venice, Po Delta, Comacchio Valleys, Pialassa della Baiona) show the merit of this approach. Indeed, when previous data are available, the ratio between the actual and background values can provide useful information on the trophic changes that have occurred in the most recent times, and the results can also explain the conditions present in less studied environments. In this context, numerous studies performed in the Venice lagoon since the second half of the 20th century during different environmental scenarios provide mean concentration ranges and propose the main causes of changes. The results of single datasets available for the other lagoons fall into scenarios that occurred in the Venice lagoon. At present, the most eutrophic basins are Pialassa della Baiona, the Po Delta lagoons and ponds and the Comacchio valleys due to industrial effluents, fish farming and clam harvesting, respectively, whereas the Venice lagoon is now experiencing environmental recovery.

Download Full-text