How to cite this article: Federica C, Marina A, Giulia R, Valentina B, Gianluca F, et al. Bioaccumulation of PCDD/Fs and PCBs in Ruditapes Philippinarum (Adams & Reeve, 1850) in Vallona Lagoon (Italy). Int J Environ Sci Nat Res. 2021; 27(1): 556203. DOI:10.19080/IJESNR.2021.27.556203
A Before-During-After environmental monitoring programme was scheduled to study possible alterations caused by the burial of an underground pipeline at the Vallona lagoon in the Northern Adriatic Sea. In this context, bioaccumulation of polychlorinated dibenzodioxins and furans (PCDDs/Fs), and polychlorinated biphenyls (PCBs) was assessed in Manila clams Ruditapes Philippinarum, from November 2005 to June 2015, to monitor possible impacts of the burial of the pipeline due to sediment resuspension. Principal Component Analysis (PCA) results highlighted the prevalent bioaccumulation of Hexa-CBs during works, whilst their concentrations were similar when comparing ante to post Philippinarumoperam-monitoring phases. In addition, presence of Tetra- and Penta-CBs also characterized some samples in the post Philippinarumoperam phase. On the contrary, the PCA applied to PCDDs/Fs showed a homogeneous situation between the three monitoring phases, except for relatively high bioaccumulation values of some congeners in two different samples collected before works. Generally, PCDDs/Fs showed a pattern of distribution of congeners typical of civil discharges, comparable with the overview of the area and mostly unrelated to the activities of burial of the pipeline.
Keywords: Biomonitoring; Adriatic sea; Po river delta; Clams; Before-during-after monitoring; Principal component analysis; Transitional water
Polychlorinated dibenzo-p-dioxins and furans (PCDDs/Fs), and polychlorinated biphenyls (PCBs), are well known persistent organic pollutants (POPs), very resistant to degradation with enhanced chronic toxicity . They can be considered as environmental indicators of anthropogenic activities, since they are always linked to activities including industrial, combustion and/or chemical processes [1-3]. PCDDs/Fs and PCBs are generally found in environment as mixtures and the pattern of distribution of congeners could identify the civil or industrial source of contamination .
The Vallona lagoon is a transitional area of about 1,150 ha located in the Po River delta that is the closure of the drainage basin of the largest and most important Italian watercourse. Moreover, Po River delta lagoons receive wastewaters from the most industrialized and densely inhabited regions of the northern Italy [4-6]. In the Vallona lagoon, Manila clam Ruditapes philipinarum has a great economic importance, since it has been widely used for bivalve farming, but it has been also used as biomonitor organism to monitor several contaminants [7-9].
During 2007-2008, a pipeline was buried in the middle of the lagoon to connect structures of the first offshore LNG terminal in
Italy to facilities on land . In view of this, an environmental monitoring programme was scheduled from 2005 to 2015, which consisted of three phases:
(iii)after the construction of the structures.
The aim of the monitoring programme was to assess possible impacts of the burial of the pipeline, and in this context, bioaccumulation of PCDDs/Fs and PCBs was assessed in R. philippinarum to monitor possible impacts in the Vallona Lagoon. Finally, this is the first study of PCDD/Fs biomonitoring, using Manila clams, in the Vallona Lagoon.
The study area was the Vallona lagoon, NE Italy (Figure 1). Manila clams (R. philippinarum) were collected by manual rake at four sites: two closer (L022 and L023) and two farther (L016 and L017) from the pipeline. Specimens were gathered in November 2005, February, April and July 2006 (anteoperam phase), November 2006, February 2007, June and November 2008 (in
opera phase), November 2010, June and November 2011, June and
November 2012, May and November 2013, June and November
2014, June and November 2015 (post Philippinarumoperam phase).
After collection, about thirty clams per sample were measured
and opened in laboratory; soft tissue were pooled (three pools of
ten clams per sample), weighted, homogenized and maintained at
-20°C until analysis.
Analysis of PCBs
Sample was extracted in an ultrasonic bath with a mixture
of n-hexane: dichloromethane 70:30 v/v. The clean-up of the
extract was performed adding concentrated sulphuric acid and
then eluting the organic phase through a Florisil cartridge with
n-hexane. The recovered fraction, containing PCB 209 as internal
standard, was analysed on a dual column Gas Chromatography
coupled with Electron Capture Detector. PCB congeners analysed
were the following: 28, 31, 35, 52, 77, 81, 101, 105, 110, 118, 126,
128, 138, 153, 156, 169, and 180.
Limit of quantitation of the method was 0.1 ng/g d.w.
Limit of quantitation of the method was 0.1ng/g d.w.
Analysis of PCDD and PCDF
Sample added with a mixture of n-hexane:acetone 50:50
was extracted in Soxhlet for 24 hours. The organic extract was
cleaned up adding concentrated acid sulphuric. The organic layer
recovered was fractioned on a silica gel column and then on a basic
alumina column. Instrumental analyses were performed by High
Resolution Gas Chromatography coupled with High Resolution
Mass Detector. PCDD/Fs congeners analysed were the following:
2,3,7,8 Tetra CDD, 1,2,3,7,8 Penta CDD, 1,2,3,4,7,8 Hexa CDD,
1,2,3,6,7,8 Hexa CDD, 1,2,3,7,8,9 Hexa CDD, 1,2,3,4,7,8,9 Hepta
CDD, Octa CDD, 2,3,7,8 Tetra CDF, 1,2,3,4,6,7,8, 1,2,3,7,8 Penta CDF,
1,2,3,4,7,8 Hexa CDF, 1,2,3,6,7,8 Hexa CFD, 1,2,3,7,8,9 Hexa CDF,
2,3,4,7,8,9 Hexa CDF, 1,2,3,4,6,7,8 Hepta CDF, 1,2,3,4,7,8,9 Hepta
CDF, Octa CDF.
Limit of quantitation of the method for the different
compounds ranged between 0.05-1 pg/g w.w.
Principal component analysis (PCA) was applied on PCBs
(grouped by Tri-, Tetra-, Penta-, Hexa- and HeptaCBs) andPCDD/
Fs (grouped by Tetra-, Penta-, Hexa-, Hepta-, Octa- CDD/Fs)
analysed in clams to elucidate bioaccumulation pattern. Statistical
processing was performed by using Software R studio .
Levels of PCDD/Fs found in Manila clams depicted higher
values mostly in the anteoperam phase (Figure 2), whilst PCBs
bioaccumulation, mostly Hexa-CB, resulted higher at the end
of in opera phase (Figure 3 & 4). However, PCBs concentrations
returned quite similar to anteoperam conditions at the end of the
post Philippinarumoperam phase.
The distribution of the PCDD/Fs concentrations (Figure 3a)
according to the first and second components accounted for 59.4%
and 12.9% of the total variance, whilst PCBs levels accounted for
49.8% and 29.5% (Figure 3b). PCDD/Fs results of PCA display
quite a good overlapping between clams sampled during ante
and post Philippinarumoperam phases, even if some samples of the first phase
well differed from their group for Hexa-CDDs and Octa-CDDs.
Moreover, post Philippinarumoperam samples differed from all the other groups.
In addition, PCBs results of PCA are homogeneous in
anteoperam phase without peculiar groups of characterizing
congeners. Indeed, some in opera samples well differed for Hexa-
CBs. Finally, most of the post operam opera samples overlapped those
from anteoperam. Only two groups of post Philippinarumoperam samples well
differed, being the first characterized by Penta-CBs and the former
PCDD/Fs and PCBs concentrations in Manila clams R.
philippinarum sampled during the BDA monitoring for a pipeline
construction in the Vallona lagoon showed quite low levels when
compared with other transitional areas with medium to low
pollution impact [12-14]. Moreover, TEQ values were always
lower than 8pg/g w.w. that is the European limit in molluscs
for human consumption (Reg. EC 1881/2006). However, the
biomonitoring results displayed higher PCB levels, especially
Hexa-CBs and Penta-CBs, during the end of the post Philippinarumoperam
phase, which persisted for a period after the burying of the
pipeline, until they finally come back similar to the anteoperam
conditions. On the contrary, PCDD/Fs showed higher levels before
the pipeline burying, whilst in the other two phases no substantial
bioaccumulation phenomena were found. Generally, a profile of
OCDD and light furans predominated all over the study, which is
mainly related to civil combustion [1,3].
The Vallona lagoon is a complex ecosystem influenced
by the Po River, which drains huge amounts of nutrients and
contaminants from intensely cultivated, and highly industrialized
inland areas of the Northern Italy . The human influence also
consists of local contamination, although in a smaller quota . In
this context, biomonitoring of PCDD/Fs and PCBs in the Vallona
lagoon highlighted the effects of pipeline burial in increasing some
PCB congeners at the end of the working phase, probably linked
to the use of working machines. However, a pattern of distribution
of PCDDs/Fs congeners typical of civil discharges, also occurred
before and after works, and they are generally comparable with
the overview of the area and mostly unrelated to the activities of
burial of the pipeline.
The environmental monitoring activities are necessary to
assess the main possible impacts associated with human activities,
such as the burial of a pipeline in very sensitive and complex
ecosystems as coastal lagoons. The adopted monitoring strategy is
confirmed to be successful when coupled with statistical analyses
that emphasize each monitoring phases, such as PCA analyses.
Indeed, they allowed to detect the fingerprints of contaminations
and to compare before during and after monitoring phases at the
Pipeline works slightly influenced PCDDs/Fs and PCBs levels in
Manila clams from the Vallona lagoon, and they quite disappeared
after a very short period, displaying a general anthropic influence
from other contamination sources in the area .