Temporal trends of polycyclic aromatic hydrocarbons (PAHs) in Dreissena polymorpha specimens from Lake Maggiore (Northern Italy)

The Lake Maggiore (Northern Italy) has been recognized as an aquatic environment heavily contaminated by persistent organic pollutants, mainly organochlorine compounds, but to date limited information is available regarding another class of widespread and hazardous pollutants, such as the polycyclic aromatic hydrocarbons (PAHs). The aim of this study was to investigate seasonal and temporal trends of 18 PAHs accumulated in native Dreissena polymorpha specimens during a 5-year biomonitoring program, as well as to identify the possible PAH emission sources by using isomeric diagnostic ratios. Zebra mussels were sampled both in their pre- (May) and post-reproductive (September) stage over the 2008–2012 period in eight sampling stations covering the whole lake shoreline. PAH concentrations were measured through gas chromatography coupled to mass spectrometry. A notable PAH contamination following an increasing temporal trend was noticed in bivalves from all the sampling stations, with the benzo(α)anthracene as the predominant compound. An overall increase in PAH levels was found in the post-reproductive surveys, indicating a marked seasonality of this contamination probably due to the increase in touristic activity during spring–summer months.     

Evaluation of several priority pollutants in zebra mussels (Dreissena polymorpha) in the largest Italian subalpine lakes

Zebra mussel (Dreissena polymorpha) has been used for the biomonitoring of several POPs (PCBs, DDTs, HCB and HCHs) in the largest Italian subalpine great lakes (Lake Maggiore, Garda, Como, Iseo and Lugano). Samplings were carried out in April 2003 at 15 locations selected according to industrial and anthropic levels of lakes. Results have pointed out high DDT levels in D. polymorpha specimens from Lake Maggiore (700-1400 ng/g lipids, 5-9 times higher than those measured in mussels of other Italian lakes), due to a contamination from a chemical plant located on one of the main lake inlet that occurred in 1996. On the contrary, PCB levels (400-2509 ng/g lipids) highlighted an overall pollution, with some sporadic peaks of contamination. Data showed a moderate increase trend compared to those found in a previous monitoring campaign carried out in 1996. Future monitoring is needed in order to confirm this tendency.     

Screening of POP pollution by AChE and EROD activities in Zebra mussels from the Italian Great Lakes

The increase of ethoxyresorufin dealkylation (EROD) and the inhibition of acetylcholinesterase (AChE) as biomarkers have been commonly used in vertebrates for the persistent organic pollutants (POPs) biomonitoring of aquatic environments, but very few studies have been performed for invertebrates. Previous researches demonstrated the interference due to some chemicals on EROD and AChE activities of the freshwater bivalve Zebra mussel (Dreissena polymorpha) in laboratory and field studies, showing its possible use for the screening of POP effects. We investigated the contamination of the Italian sub-alpine great lakes (Maggiore, Lugano, Como, Iseo, Garda) by the biomarker approach on Zebra mussel specimens collected at 17 sampling sites with different morphometric characteristics and anthropization levels. Results showed a homogeneous contamination of AChE inhibitors in Lake Garda, Maggiore, Como and Iseo with values ranging from 0.5 to 3 nmol/min/mg proteins and with an average inhibition of about 66% to controls. The planar compounds pollution, able to activate the EROD activity, seems higher in some sampling stations of Lake Garda, Como and Iseo (2-4 pmol/min/mg proteins) than that measured in Lake Lugano (1.5-3 pmol/min/mg proteins). On the contrary, the enzyme activity in Lake Maggiore showed an interesting opposite effect of AhR-binding compounds and trace metals. Finally, the possible use of Zebra mussel specimens maintained at laboratory conditions as controls against the selection of the less polluted sampling site is discussed.     

DDT is still a problem in developed countries: the heavy pollution of Lake Maggiore

The Zebra mussel (Dreissena polymorpha), one of the most widely used bioindicators of persistent organic pollutants, trace metals and radionuclides in several worldwide freshwater ecosystems, has been used to monitor DDT contamination trends in Lake Maggiore since 1996, caused by industrial effluents on a tributary of the River Toce, one of the major affluents of the lake. Dreissena specimens were collected at two sampling sites, one within the Baveno Bay, where the River Toce flows, and the other outside (Villa Taranto). Total DDT levels (3119.6 ng/g lipids at Baveno and 1351.2 ng/g lipids at Villa Taranto) in the soft tissues of the Zebra mussel decreased at both stations by about 30-50% in the first year after the closure of the chemical plant reaching an almost steady-state condition. The high concentrations measured in Zebra mussel specimens of Baveno Bay in 2000 (1947 ng/g lipids) and the percentage of pp'DDE in comparison with total DDT concentration, which showed a slight increase in the last years, clearly indicate that a contamination source is still present, deriving probably from the lacustrine sediments and the River Toce. Data show that the environmental risk is very high within the Baveno Bay and the recovery time should be longer than in the other parts of the lake, where DDT levels in Dreissena are presently two times higher than those measured in the other Italian subalpine lakes.     

Present status of POP contamination in Lake Maggiore (Italy)

In the last decade, Lake Maggiore has been subject to heavy DDT contamination due to a chemical plant located near the main influent of the Baveno Bay. The freshwater bivalve zebra mussel (D. polymorpha) was used as a bioindicator of several POPs (DDTs, PCBs, HCB, HCHs) to follow their concentration trend after a heavy flood in autumn 2000. Sampling of mollusc specimens were carried out monthly from April 2001 to October 2002 at two different stations in and outside the bay. Results showed worsening of DDT pollution due to the transport of insecticide from contaminated sediments and soils still present in the closed chemical plant site. Levels of about 4.5 microg/g lipids in soft tissues of specimens from the most contaminated site and 2.0 microg/g lipids outside it were found, which are twice those measured before the flood. HCHs and HCB values were always very low, but it was noticed since winter 2001-2002 a sharp increase of PCB pollution, with values of about 3-4 microg/g lipids, not due to the 2000 flood, but probably to improper discharge or release of contaminated sediments from numerous dams located in the watershed. Concentrations of total dioxin-like PCBs reached dangerous levels for the water community. Fish consumption may be a risk for human health especially for resident population, bearing in mind that fish usually have a higher POP concentration than zebra mussel.     

pp´DDT and pp´DDE Accumulation in a Food Chain of Lake Maggiore (Northern Italy): Testing Steady-State Condition

- DOI: http://dx.doi.org/10.1065/espr2006.01.010 Background, Aims and Scope Although pp'DDT usage was strongly limited or banned in most parts of the world during the last three or four decades, the parent compound, its homologues and their metabolites still occur at levels which might pose a risk for many ecosystem components. A case of DDT pollution of industrial origin was discovered in 1996 in Lake Maggiore, the second largest (212 km2) and deepest (370 m) lake in Italy, causing concern for wildlife and human health. The extensive monitoring of many biotic and abiotic compartments which followed from 1998 in order to assess the pollution level and its trend in time, provided a great availability of data referring to DDT contamination of the different fish species of the lake. In this study, the recent contamination levels in selected fish species were compared to those measured in 1998 to evaluate the temporal pollution trend of the lake and its natural recovery, given that no remediation measures were carried out on the contaminated soils and sediments in this time span. Moreover, a modelling approach to test the equilibrium condition between water and pelagic fish species was used. Analytical results of pp'DDT and pp'DDE concentrations in lake water were used as input data in the bioenergetic model by Connolly & Pedersen (1988) to calculate concentrations in two fish species and to compare the predicted and the measured contamination. Methods Sampling and analytical determination of DDT homologues in lake water: Five water sampling campaigns were carried out from May 2002 to February 2004 in three sampling sites of Lake Maggiore. Suspended and dissolved pollutants were determined separately. Quantitative DDT homologue analyses were performed by HRGC coupled with ECD detection by the external standard method. Single water extracts were put together in correspondence with the stratification zones of the water column inferred on the basis of the temperature profile to improve analytical sensitivity. Selection of fish data: Concentrations of DDT and DDE in fishes were selected from recent literature (CIPAIS 2003, 2004). Bioaccumulation model: The bioenergetic model proposed by Connolly & Pedersen (1988) was used to assess the bioaccumulation of pp'DDT and pp'DDE of Alosa fallax (landlocked shad) and Coregonus spp. (whitefish), selected among the different species as representative of a secondary consumer level. Results and Discussion The average concentrations of pp'DDT and pp'DDE in water to be used as input data in the bioenergetic model were obtained considering all the concentrations measured at the three sampling stations in the epylimnion where the fish species considered in this study spend most of their life. The resulting values were 0.05 and 0.16 ng/L for pp'DDT and pp'DDE, respectively. Average measured pp'DDT and pp'DDE concentrations in landlocked shad were 0.81 +/- 0.39 and 1.69 +/- 0.71 mg/kg lipids, respectively, and were 0.29 +/- 0.12 and 1.06 +/- 0.41 mg/kg lipids for the whitefish. Calculated and measured values turned out to be in quite good agreement for pp'DDT, while measured pp'DDE concentrations were higher than expected on the basis of the bioenergetic model in both species. Probably metabolic transformations of pp'DDT accumulated in fish tissues in the past are responsible for the observed differences between calculated and expected pp'DDE concentrations in fish. Conclusions Pelagic fishes of Lake Maggiore seem to maintain the DDT accumulated during their life time and the most efficient mechanism responsible for the fish population recoveries is probably their generation changes; for this reason, equilibrium models cannot be used until negligible pp'DDT concentrations are reached in fish tissues. Recommendations and Outlook The limit proposed for pp'DDT in water by the EU Directive 2000/60, which will come in force in 2008, is 0.2 ng/L, four times higher than the average concentration measured in Lake Maggiore waters. Nevertheless, concentrations measured in Lake Maggiore fish were very close and sometimes exceeded the Maximum residue limits (MRLs) settled by the Italian legislation for foods (0.1 mg/kg w.w. for fish containing 5–20% lipid). It seems, therefore, that the 'environmental quality standard' of 0.2 ng/L cannot guarantee the suitability of fish for human consumption.     

Use of zebra mussel (Dreissena polymorpha) to assess trace metal contamination in the largest Italian subalpine lakes.

Trace metal (Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn) contamination was evaluated in zebra mussels from the lakes Maggiore, Lugano, Como, Iseo and Garda, which are located in the most highly populated and industrialised area in Italy. Zebra mussels from Lake Maggiore contained the highest concentrations (3.44, 1.51, 4.97, 0.158, 5.87, 346 microg g(-1) for Cd, Co, Cr, Hg, Pb, Zn, respectively) of all metals analysed except Cu and Ni. The lowest levels of most metals were in animals from Garda and Lugano (0.78 and 0.60 microg g(-1) for Cd, 2.87 and 2.03 microg g(-1) for Cr, 0.065 and 0.049 microg g(-1) for Hg, 12.1 and 11.9 microg g(-1) for Ni, 1.96 and 2.46 microg g(-1) for Pb, 158 and 163 microg g(-1) for Zn). The most contaminated sites and possible local sources of metals were identified for each lake, and the lakes classified into quality classes concerning metal pollution.     

Seasonal fluctuations of DDTs and PCBs in zooplankton and fish of Lake Maggiore (Northern Italy)

Concentrations of DDTs and PCBs were determined in the zooplankton and in three different fish species (shad, whitefish and roach) collected seasonally during 2009 and 2010 in three sites in Lake Maggiore, a south-alpine lake that has been contaminated by DDT since 1996. As previously observed in 2008, even during 2009 DDTs concentrations were higher in zooplankton than in fish, probably due to the very unstable situation of the lake still influenced by local inputs. The situation changed in 2010, when all DDT compounds increased in fish to levels much higher than those measured in zooplankton. Biomagnification was statistically demonstrated for pp′DDE in all the three fish species, indicating a probable signal of recovery of the lake.Although with respect to total PCBs we observed that the contamination levels varied across time periods and across fish species, biomagnification was evident from zooplankton to fish both in 2009 and in 2010. As concern individual PCBs, biomagnification from zooplankton to all three fish species was significant for PCB 153 and PCB 138.     

Concentrations,distributions, sources,and risk assessment of organochlorine pesticides in surface water of the East Lake,China

East Lake resides in the urban area of Wuhan City and is the largest urban lake in China. The concentrations of 16 organochlorine pesticides (OCPs) were analyzed in 108 surface water samples collected from the East Lake. The total concentrations of OCPs ranged from not detected to 120 ng L^?1 with predominance of δ-HCH, heptachlor, and α-HCH. The mean values of HCHs and DDTs were 7.40 and 5.70 ng L^?1, respectively, accounting for 40 and 31 % of the total OCPs. For the five lakelets in East Lake, Houhu Lake exhibited the highest concentrations of HCHs, DDTs, and total OCPs, which has been used actively for fisheries and surrounded by suburban rural areas and farmlands. Historical lindane or technical HCH input was probably the source of HCH, while technical DDTs might be the source of DDT in the East Lake. The ratio between heptachlor and its metabolic products indicated recent input of heptachlor. Although the combining ecological risks for all aquatic species in the East Lake calculated by species sensitivity distribution reached approximately 10^?5, the OCPs in the East Lake had slight effects on aquatic organisms. The carcinogenic risks and non-carcinogenic hazard indices of DDTs and HCHs indicated that water in the East Lake was not suitable as water sources for human. However, the results indicated the water quality was safe for people to swim in the urban lake.     

Contamination by polybrominated diphenyl ethers of sediments from the Lake Maggiore basin (Italy and Switzerland)

Polybrominated diphenyl ethers (PBDEs) are characterized by chemical properties and toxicological profiles similar to other POPs (persistent organic pollutants) included in the EU Priority Pollutant List (2455/01/CE). However, limited data have been available for these compounds thus far for Italian freshwater abiotic matrices. Lake Maggiore basin, a heavily industrialized and densely populated area, was selected for studying PBDE contamination in Italy. PBDEs and OCs (organochlorine compounds) in the basin were quantified by analysing both sediment cores collected in 2005 from the lake and grab samples from the main tributaries and the emissary. Fourteen PBDEs, from tri-BDE to hepta-BDE congeners and BDE209, were compared with some organochlorine POPs (PCBs and DDTs) characterizing Lake Maggiore basin contamination. Analyses of tri-to hepta-BDEs, PCBs and DDTs were undertaken by GC-MS/MS, while BDE-209 was analysed by GC/ECD. Results showed a dominant presence of BDE-209 (>95% of SigmaBDE) and limited amounts of BDE-47, BDE-99, BDE-100, BDE-153 and BDE-154. Lake core profiles highlighted a decreasing trend in PCB concentrations starting from the year 2000, while PBDEs showed greater concentrations after the beginning of the 1990s (up to 30 ng g(-1)d.w.). Among the tributaries, the Bardello and Boesio rivers were the most PBDE-contaminated (up to 290 ng g(-1)d.w.).     

Evaluation of spatial distribution and accumulation of novel brominated flame retardants,HBCD and PBDEs in an Italian subalpine lake using zebra mussel (Dreissena polymorpha)

Because of the reduction in the use of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD), novel brominated flame retardants (NBFRs), including 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), decabromodiphenyl ethane (DBDPE), hexabromobenzene (HBB), and pentabromoethylbenzene (PBEB), started to be marketed as alternatives to the banned formulations. In this study, the spatial distribution and accumulation of NBFRs, PBDEs, and HBCD in the biota have been investigated in the littoral compartment of a large and deep subalpine lake (Lake Maggiore, Northern Italy), using zebra mussel Dreissena polymorpha and roach (Rutilus rutilus) as bioindicators. To our knowledge, this is the first study reporting the contamination of NBFRs in the freshwater invertebrate D. polymorpha. Contamination of zebra mussel due to PBEB, HBB, and BTBPE was low, ranging from 0.9 to 2.9 ng/g lipid weight, from 1.1 to 2.9 ng/g l.w., and from 3.5 to 9.5 ng/g l.w., respectively. PBEB and BTBPE in roach were always below the detection limit, while the contamination of HBB ranged from < limits of detection (LOD) to 1.74 ng/g l.w., indicating a weak contamination. DBDPE was < LOD in all the considered biological samples. Finally, HBCD was detected in all organic tissues with mean concentrations up to 74.4 ng/g l.w. PBDE results, supported by principal component analysis elaboration, suggested a possible contamination due to the congeners composing the penta- and deca-BDE technical formulations, which are present in the Lake Maggiore basin. The biomagnification factor values showed that tetra- and penta-BDE biomagnified, while octa-, nona-, and deca-BDE were still bioavailable and detectable in the fish muscles, but they do not biomagnified. Considering the other BFRs, only HBCD showed a moderate biomagnification potential.     

Mercury accumulation in marine bivalves: influences of biodynamics and feeding niche

Differences in the accumulation of mercury (Hg) in five species of marine bivalves, including scallops Chlamys nobilis, clams Ruditapes philippinarum, oysters Saccostrea cucullata, green mussels Perna viridis, and black mussels Septifer virgatus, were investigated. The bivalves displayed different patterns of Hg accumulation in terms of the body concentrations of methylmercury (MeHg) and total Hg (THg), as well as the ratio of MeHg to THg. Parameters of the biodynamics of the accumulation of Hg(II) and MeHg could reflect the species-dependent Hg concentrations in the bivalves. With the exception of black mussels, we found a significant relationship between the efflux rates of Hg(II) and the THg concentrations in the bivalves. The interspecific variations in the MeHg to THg ratio were largely controlled by the relative difference between the elimination rates of Hg(II) and MeHg. Stable isotope (δ¹³C) analysis indicated that the five bivalve species had contrasting feeding niches, which may also affect the Hg accumulation.     

Levels and congener profiles of polybrominated diphenyl ethers (PBDEs) in Zebra mussels (D. polymorpha) from Lake Maggiore (Italy)

Several congeners of polybrominated diphenyl ethers (PBDEs) were monitored in 14 different sampling stations of Lake Maggiore, the second largest Italian lake in regard to surface, volume and average depth, using the sentinel-organism Zebra mussel (Dreissena polymorpha). Results revealed a moderate contamination with summation operatorPBDE levels (BDE-17, -28, -47, -66, -71, -85, -99, -100, -138, -153, -154, -183, -190 and -209) ranging from 40 to 447ngg(-1) lipid weight which are similar to those found in environments polluted by deposition or atmospheric transport. The general order of decreasing congener contribution to the total load was BDE-47>-99>-100>-209, which closely reflected patterns observed in mussels collected in freshwater ecosystems worldwide.     

Cadmium and zinc bioaccumulation and metallothionein response in two freshwater bivalves (Corbicula fluminea and Dreissena polymorpha) transplanted along a polymetallic gradient

This study was designed to compare the metallothionein (MT) response capacity of two freshwater bivalves, Corbicula fluminea and Dreissena polymorpha, along an environmental gradient of polymetallic pollution. The bivalves were transplanted into 4 stations in southwestern France, with a cadmium and zinc pollution gradient. MT and metal concentrations were measured in the soft bodies of the clams and mussels over 2.5 months. In the zebra mussels, variations in MT concentrations were strictly correlated to progressive Cd and Zn bioaccumulation. In contrast, the faster response in the clams appeared positively correlated to Cd accumulation only, with the activation of efficient detoxification mechanisms which limited Cd bioaccumulation and reduced Zn concentrations over time. Nevertheless, despite stronger metal accumulation factors in D. polymorpha, C. fluminea revealed higher sensitivity of MT response along the pollution gradient.     

DDT contamination in Lake Maggiore (N. Italy) and effects on zebra mussel spawning.

Zebra mussel (Dreissena polymorpha) is commonly used as contaminant bioindicator in Europe and North America. We used the zebra mussel to follow DDT pollution trends from 1996 to 1997 in Pallanza bay, Lake Maggiore, near the inlet of the River Toce, after a DDT-manufacturing plant discharging residues into a tributary of the River Toce had closed down. DDT contamination fell off sharply outside the bay, but tissue concentrations of the parent compound and residues remained high in molluscs sampled within the bay a year later. Molluscs collected in Pallanza bay in June 1997 released gametes earlier than those sampled at a nearby reference station. Histological studies showed that a significant percentage of these specimens showed marked oocyte degeneration suggesting that DDTs have endocrine-disrupting effects in this species.     

High prevalence of infections and pathological changes in burbot (Lota lota) from a polluted lake (Lake Mjøsa,Norway)

The aim of the present study was to investigate whether exposure to high levels of persistent organic pollutants (POPs) affected a fish population in Lake Mjøsa. Lake Mjøsa is known to be contaminated by polybrominated diphenyl ethers (PBDEs), a subgroup of brominated flame retardants from local industrial activities. Fish from Lake Losna, a less contaminated lake located close to Lake Mjøsa, was used as reference (control).The sampling of burbot (Lota lota) was carried out between 2005 and 2008. Hepatic levels of POPs were analysed in burbot from the two lakes, and the fish were examined for bacterial- and parasite infection and histopathological changes. The levels of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), and PBDEs were about 10, 15 and 300 times higher in fish from Lake Mjøsa compared to fish from Lake Losna. Mycobacterium salmoniphilum was present in 7% and 35% of the fish from Lake Losna and Lake Mjøsa respectively. Significantly higher number of external and visceral macroscopic lesions, histopathological diffuse changes and granulomas were seen in fish from Lake Mjøsa compared to Lake Losna. Furthermore the parasite infection was higher and the hepatic lipid content was significantly lower in burbot from Lake Mjøsa. The results of the present study suggest that the high level of contamination in Lake Mjøsa could have a negative impact on the health status of wild fish inhabiting the lake.     

DDT polluted meltwater affects reproduction in the mussel Dreissena polymorpha

The zebra mussel Dreissena polymorpha was used to follow the recently reported DDT pollution of Lake Iseo (N. Italy). Histopathological analyses were performed on mussels sampled from March 2005 to April 2006, when high DDT levels were found, and results were compared to those from mussels sampled in 2001/2002, before the pollution event. During the 2005/2006 reproductive season, the first male gamete release happened one month later than the onset of spawning in females who showed a high number of specimens with degenerating oocytes, despite a regular pattern of gametogenesis. These results indicated a disrupting action of DDT on the mechanisms involved in sperm release, and a disturbance in the gametogenic phases of the ovary. Pathological pictures in the digestive gland of many mussels from both 2001/2002 and 2005/2006 have also been observed, but DDT pollution is unable to explain the presence of pathological fields in mussels during 2001/2002, for which a previously reported contamination seems to be the main cause. A possible role of DDT in skewing the sex ratio towards a predominance of females was also discussed, considering the high number of females sampled in 2005/2006.     

The role of zooplankton in DDT biomagnification in a pelagic food web of Lake Maggiore (Northern Italy)

Background  

In the present study, we report the analytical results of pp′DDT, pp′DDE and pp′DDD determination in lake water, plankton and zooplanktivorous fish of Lake Maggiore (Northern Italy), rather recently polluted by DDT of industrial origin, in order to understand the bottom-up pollution transfer among the abiotic and biotic components of the lake ecosystem.     

Sedimentary record of polycyclic aromatic hydrocarbons and DDTs in Dianchi Lake, an urban lake in Southwest China

Unique time trends of polycyclic aromatic hydrocarbons (PAHs) and dichlorodiphenyltrichloroethanes (DDTs) were found in a dated sediment core from Dianchi Lake (DC), an urban lake in Southwest China. The temporal trend of PAHs in DC was not only different from those in China's coastline and remote lakes of China, but also different from those in more developed countries. Identification of sources suggested that PAHs in DC originated primarily from domestic combustion of coal and biomass. However, a change of source from low- and moderate-temperature combustion to high-temperature combustion processes was observed. Different from those in China's coastline and some developed countries, the temporal trend of DDTs in DC mirrored the historical usage of DDTs in China, with erosion of soils and surface runoff from its drainage area the most likely routes of DDT introduction to the lake. Rapid urbanization and industrialization in its catchment, effective interception of point-source pollution, and changes in sources of energy during the last few decades have significantly influenced the vertical profiles of PAHs in DC.     

Preliminary investigation of a sensitive biomarker of organotin pollution in Chinese coastal aquatic environment and marine organisms

In nine batches of sea bivalves collected from Chinese coastal cities during the year of 2000 to 2002, a special sample named Mya arenaria was found to have strong ability of butyltin accumulation compared with the other sampled bivalves in the corresponding batches. Tributyltin compound was the predominant pollutant with the detection rate high up to 100%. Special high levels of g Sn/g were detected in some Mya arenaria samples. The results obtained showed that Mya arenaria was potentially a biomarker to indicate organotin pollution in coastal aquatic environment.