# DPSIR Model Applied to the Remediation of Contaminated Sites. A Case Study: Mar Piccolo of Taranto
## 7 Impacts  
### Contaminants Mobility  
It is extremely important to understand the mobility and availability of pollutants in environmental matrices. [PERSON] et al. [58] investigated the effects of sediment resuspension on the fate of PCBs. Sediments and water were collected nearby the most contaminated site in the Mar Piccolo basin. PCBs in sediments after resuspension increased by 15%. Instead, after resuspension, PCBs in the dissolved phase increased from 0.82 to 4.82 ng/L and from 0.22 to 202.21 ng/L in the particulate one. In addition, the dissolved phase in water was found enriched in light-to-mid-weight compounds, and, conversely, the particulate phase was enriched in heavier congeners after the resuspension. A correlation was found with the dissolved organic carbon (DOC) that increased from 1.31 to 8.55 mg/L, likely influencing the fate of metals and PCBs in the dissolved and particulate phases. The Italian research center of Taranto investigated the role of granulometry, bioavailability, and mobility of pollutants [31]. They considered two stations in the Arsenal area for sediment sampling:  
The granulometry of Station 1 was represented by: 6.2% gravel, mostly made of biological material, 20% sand, 74% mudstone (silt and clay);  
The granulometry of Station 2 was represented by: 7% gravel, 15% sand, 78% mudstone. \begin{table}
\begin{tabular}{c c} \hline \hline
**Litter Typology** & **Total** \\ \hline Car and truck & 90 \\ Parts of car & 34 \\ Motorcycle & 13 \\ Battery & 20 \\ Tire & 234 \\ Bicycle & 5 \\ Wreck with hull & 91 \\ Wreck with motor & 13 \\ Industrial propeller/fan & 3 \\ Drum and large barrel & 14 \\ Medium and small barrel/tin & 25 \\ Fishing net and rope & n.d. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Typology and quantity of mega-litter observed at three critical areas in the Mar Piccolo [57]. It is evident that the high percentage of fine and extremely fine fractions in sediments of the Mar Piccolo leads to a higher possibility to connect with pollutants [59]. Concerning PCBs, Station 2 was found to be more contaminated than Station 1. In fact, the sum of PCB \(\sum\) 28 in Station 1 was equal to 1986 ng/g d.w. and 3278 ng/g d.w. in Station 2. In both cases, however, values exceeded the ICRAM threshold limit, equal to 190 \(\mu\)g/Kg d.w. (sum of PCB 28, 52, 77, 81, 95, 99,101, 105, 110, 118, 126, 128, 138, 146, 149, 151, 153, 156, 169, 170, 177, 180, 183, 187). Even in this case, it is interesting to quantify PCBs contained in the mudstone fraction. In particular, 43% and 52% of PCBs were detected in the fraction <63 \(\upmu\)m, respectively, in Station 1 and 2. Values of As, Cu, Pb, Zn, and Hg in both stations exceeded ISPRA threshold limits (as 20 mg/Kg d.w.; Hg 0.8 mg/Kg d.w.; Pb 50 mg/Kg d.w.; Cu 45 mg/Kg d.w.; Zn 110 mg/Kg d.w.). Table 3 shows the amount of metals detected in all sediment and the mudstone fraction (<63 \(\upmu\)m). They also carried out a speciation analysis by using the method of [PERSON] et al. [60], according to which the suspended sediment samples are subjected to a sequential extraction procedure designed to partition the particulate trace metals into five fractions: (F1) exchangeable; (F2) bound to carbonates; (F3) bound to Fe/Mn oxides; (F4) bound to organic matter; F5) residual. No evident differences were noted in the distribution percentage of geochemical fractions between the two stations. Figure 14 shows that more than 80% of Cu is linked to the organic matter (F4), and only a small amount is associated with residual. Cr, V, and Ni are found mainly in the residual fraction (about 70%), and a small amount is connected to iron oxides and Mn and a smaller quantity to organic matter. Lead is found essentially bound to iron and manganese oxides (about 60%) and organic matter (about 25%). The small quantity of lead in the residual fraction confirmed the anthropic origin. Zinc shows a similar behavior of Pb and, according to [PERSON] and [PERSON] [61], it decreases with sulfides increasing in sediments.