Quality assessment of bed sediments of the Po River (Italy).
Comprehensive and contemporary evaluations of physical, chemical and toxicological endpoints have been performed on bed sediments of the Po River, the major Italian watercourse. Two extensive sampling campaigns were conducted in summer and winter low-flow conditions. Composite sediment samples were collected from ten reaches of the main river: the first was located in the upper region (ambient control), and the others downstream of the confluences of nine principal tributaries. The two sampling programs were paralleled by contemporary investigations on the macroinvertebrate community. The particle-size composition along the Po River showed a relatively uniform distribution of fine sand, a progressive downstream decrease of coarse sands and a corresponding increase of fine materials. The levels of polychlorinated biphenyls (PCB), polycyclic aromatic hydrocarbons (PAH), extractable organo halides (EOX), Cd, Cr, Cu, Hg, Ni, Pb and Zn were determined in sediment fine particles (< 63 microm), and showed marked changes across the ten river reaches. Their longitudinal trends, as those of organic carbon and total nitrogen, were very similar and largely independent of the survey season. Sediment quality benchmarks were used to evaluate sediment chemistry, and, although the overall level of contamination was from moderate to low, the reaches located downstream of the tributaries Dora Riparia, Dora Baltea, Lambro and Oglio were considered to be at risk. Sediments were tested for toxicity on Oncorhynchus mykiss, Ceriodaphnia dubia, Raphidocelis subcapitata and Vibrio fischeri. The toxicity tests were conducted both with sediment extracts and whole samples. Sediment extracts showed toxic potentials that were consistent with the spatial distribution of contaminants. Whole-sediment toxicity showed moderate/low effects which also included false positives and negatives. Alterations of the macroinvertebrate community were found for many kilometers downstream of Dora Riparia, and with a seasonal dependence, also in other reaches of the Italian river. Principal component analysis (PCA) was used to describe the longitudinal and temporal changes of the Po River, and allowed the selection of the most useful and discriminating indicators.
Viganò
Luigi
L
Istituto di Ricerca Sulle Acque, CNR, 20047 Brugherio, Milan, Italy. vigano@irsa.rm.cnr.it
Arillo
Attilio
A
Buffagni
Andrea
A
Camusso
Marina
M
Ciannarella
Ruggero
R
Crosa
Giuseppe
G
Falugi
Carla
C
Galassi
Silvana
S
Guzzella
Licia
L
Lopez
Antonio
A
Mingazzini
Marina
M
Pagnotta
Romano
R
Patrolecco
Luisa
L
Tartari
Gianni
G
Valsecchi
Sara
S
D000818:Animals; D000460:Chlorophyta; D033361:Cladocera; D004784:Environmental Monitoring; D004785:Environmental Pollutants; D019015:Geologic Sediments / Q000737:chemistry*; D007558:Italy; D019216:Metals, Heavy / Q000009:adverse effects / Q000032:analysis*; D017686:Oncorhynchus mykiss; D011078:Polychlorinated Biphenyls / Q000009:adverse effects / Q000032:analysis*; D011084:Polycyclic Aromatic Hydrocarbons / Q000009:adverse effects / Q000032:analysis*; D018570:Risk Assessment; D018675:Toxicity Tests; D014733:Vibrio
D004785:Environmental Pollutants; D019216:Metals, Heavy; D011084:Polycyclic Aromatic Hydrocarbons; D011078:Polychlorinated Biphenyls