River Lambro Research Articles

Acque che scorrono, storie che rimangono: il fiume Lambro come archivio della memoria collettiva

Abstract Flowing Waters, Lasting Stories: the Lambro River as an Archive of Collective Memory The Lambro River has profoundly shaped Lombardy’s landscape and local communities throughout history. This paper aims to investigate the connection between the river and the identity of these communities by analyzing how changes in landscape have been reflected in both tangible and intangible cultural expressions. Studying this heritage offers insights into how the Lambro has been perceived and integrated into the local community’s identity over time, becoming a fundamental element of their sense of belonging. To achieve this objective, this research uses art, literature, and music, which not only portray the region but also provide valuable insights in the evolution of collective identities across generations.

Fringe renewal. Enhancing urban and peri-urban fragile areas

This doctoral design-driven research investigates the spatial renewal and urban regeneration of four areas of the case study Eastern fringe of Milan. Each design experimentation focuses on peculiar topics related to urban fringes' renewal which were selected due to the specificities of each area within the broader urban fringe, which is strongly characterized by the presence of different infrastructures – the Lambro river, the railways and the A51 highway ‘Autostrada Tangenziale Est'. Design approaches illustrated in the following visual essays are based on surveys and datasets; they test design strategies through specific toolkits aimed at enhancing spatial relations and urban quality and reacting to climate change through mitigation and adaptation actions.

The last 50 years of organic contamination of a highly anthropized tributary of the Po River (Italy)

We examined the temporal profiles of many organic micropollutants analysed in a sediment core sampled from a highly anthropized tributary of the Po River, the Lambro River. Analysed for extractable organic halogens (EOX), total petroleum hydrocarbons (C10–C40TPH), polycyclic aromatic hydrocarbons (PAHs), common legacy pollutants (DDTs, PCBs), halogenated flame retardants (PBDEs, DBDPE, TBBPA-bis, TCBPA, TBBPA, HBCDs), organotins (TBT, TPhT), antimicrobials (TCS, TCC), fragrances (AHTN, HHCB) and phthalates (DMP, DEP, DnBP, BBP, DEHP, DnOP), the dated sediment core revealed the historical record of 50 years of chemical contamination discharged into the Lambro and thereby the Po River. In this regard, the peak levels of PCBs and DDTs found in Lambro sediments were also identified in other sediment cores collected from the Po River prodelta in the Adriatic Sea, thus hundreds of kilometres downstream (Combi et al., 2020). The highest risk to aquatic organisms was associated with decades of high levels of C10–C40 TPH, PBDEs, PCBs, PAHs, DDTs, EOX, TCC, AHTN and DEHP, which in different periods of the contamination history, showed exceedances of guideline/threshold values. C10–C40 TPH and TCC, for example, were very high in the 1960s, whereas PCBs, DDTs, and PBDEs, peaked from the 1980s onward. The corresponding sums of PEC quotients ranged between 0.48 and 28.63, with a mean value (±SD) for the entire recording period of 10.62 ± 9.83. Environmental legislations and improved wastewater treatments were the main drivers of the recent downward trends observed for most of the chemicals investigated. Floods in turn resulted in macroscopic yet temporary improvements in the chemical quality of the tributary, conveying contaminated sediments into the Po River.

Analysis of the 16S rRNA gene for the characterization of the bacterial community of the Lambro river (Italy)

Characterization of the microbial community of a river can provide various indications, such as its general state of health or the presence of contamination. Furthermore, the study of Bacteroidetes, which have a high degree of host specificity, can provide information on the species involved in any fecal contamination. The analysis of the 16S rRNA was used to characterize the bacterial community of the Lambro river (Italy) through. The results, which were obtained by analyzing water from 15 sampling points, show a reduction in the complexity of the bacterial community as the river enters a densely populated region. The cause could be a source of chemical or physical contamination that carries out a positive selection toward some bacterial species and negative toward others. In addition, a notable increase in the percentage of Bacteroidetes was reported, especially when the river enters regions characterized by high agricultural and livestock activity, such as cattle and pig farming. However, in the samples taken from this area, no Bacteroidetes ascribable to these two species or to the other species considered (i.e., human, dog, and cat) were found. Surprisingly, suspected bacterial contamination of swine origin was identified in a sparsely populated region characterized by small family farms. Finally, the efficient treatment of urban wastewater was confirmed as no markers of fecal pollution of human origin were identified.

A realistic approach for the assessment of plastic contamination and its ecotoxicological consequences: A case study in the metropolitan city of Milan (N. Italy)

The study of the contamination of plastic mixtures sampled in natural environments is currently focused on their qualitative and quantitative assessment, while the evaluation of their effects on organisms is normally performed by experiments carried out at exposure conditions (size, shape, polymers) often far from the environmental ones. To improve the ecological realism, the aim of this study was to collect different plastic mixtures in 9 sampling stations located in 7 watercourses within the metropolitan city of Milan, one of the most anthropized and industrialized European areas, to evaluate both their qualitative and quantitative characteristics and, at the same time, to assess their ecotoxicological effects by exposing for 7 days some specimens of the freshwater bivalve Dreissena polymorpha to the mixtures collected in the sampling sites. The plastic characterization was performed by a Fourier-Transform Infrared spectrometer coupled with an optical microscope (μFT-IR), after several stages aimed to sample cleaning, separation of plastics and visual sorting. The possible effects caused by the plastic mixtures were carried out by the measurements of a biomarker suite to evaluate many cellular and molecular endpoints in mussel tissues. The main results showed a widespread and heterogeneous contamination of plastics in the entire metropolitan area, with contamination peaks found above all in the only two rivers of natural origin (Olona River and Lambro River) where comparable or higher values were reached than plastic concentrations measured in several European rivers. Despite this worrying contamination, the ecotoxicological data obtained after the exposures to the plastic mixtures collected in the selected water bodies showed only a mild effect on oxidative stress and on the variation of some antioxidant enzymes.

Presence of carbepenemase-producing Enterobacteriaceae in the River Lambro basin, Italy: might sediment represent an important resistance reservoir?

In the last years, the rapid spread in anthropized ecosystems of pathogens which are resistant to carbapenem antibiotics has raised great concern. In this study, KPC-producing Klebsiella pneumoniae was found in the River Lambro in June 2019, whereas KPC-producing Klebsiella oxytoca and Citrobacter braakii were identified in untreated wastewaters. Susceptibility profiles indicated resistance to imipenem, ertapenem and meropenem. Different carbapenamase genes (blaKPC, blaNDM, blaVIM, blaOXA-48) were also found in the River Lambro, although not associated to living bacteria. The presence of a wide set of carbapenemase genes and resistant pathogens show that river sediments could act as a reservoir of antibiotic resistance potentially threatening human health.

Vertical profiles of trace elements in a sediment core from the Lambro River (northern Italy): Historical trends and pollutant transport to the Adriatic Sea

River sediments generally act as a sink for trace elements but, when resuspended, they contribute to long-term downstream transport of contamination, which may finally reach the marine environment. This study analyzed these processes in a complex aquatic system that includes a contaminated tributary, the Lambro River (Northern Italy) and its recipient and main Italian watercourse, the Po River, with the prodelta in the Adriatic Sea. The study was conducted from a historical perspective which, covering the last 50 years, examined the main driving events such as the inputs of contaminants, the construction of WWTPs and the evolution of environmental legislation. The time trend of trace element contamination was analyzed in a sediment core collected in the Lambro River and dated 1962–2011. The highest enrichments were found for Hg, Zn, Cu, Pb and Cd, which showed similar trends, with EF maxima in the '60s–'90s (172, 56, 40, 28 and 21, respectively), following industrial and urban development, and a general decreasing pattern after the late ‘90s. Only in the 2000s the ecological risk associated with metal contamination showed mean PEC Quotients stably below 1. The results of a literature survey on sedimentary trace elements in the Po River and the prodelta for the last 50 years were then compared to the Lambro sediment core. A significant contribution to Cu, Zn, Pb, Hg and Cd contamination was proved to derive from Lambro sediment transport. In the prodelta, increasing Ni and Cr concentrations were also evidenced, likely as a result of enhanced soil erosion in the Po basin. This study highlights the key role of WWTPs, of lower-impact industrial processes and of environmental legislation in reducing contaminant inputs. It also emphasizes the active contribution of riverine sediment-bound contamination to long-distance marine sediment quality.

Characterization of plastics and their ecotoxicological effects in the Lambro River (N. Italy)

This study had the dual objective of both the qualitative and quantitative assessment of plastic mixtures sampled in 5 different sites located along the Lambro River (northern Italy), and the contemporarily determination of the ecotoxicological effects of the same mixtures sampled, through 21-day laboratory exposures of the freshwater bivalve Dreissena polymorpha. The monitoring survey was carried out by a Fourier Transform Infrared Microscope System, while the ecotoxicological assessment was performed by the mussel mortality, a biomarker suite and the proteomics. The main results of the monitoring have highlighted some critical points, related to the concentration of plastics detected at Milan and, especially at the southernmost sampling station, where a daily flow of more than 6 million plastic debris has been estimated, ending directly into the Po River, the main Italian river. The ecotoxicological analysis highlighted how the toxicity is not exclusively due to the plastic concentration, but that the different characteristics of the polymers probably become more important. Furthermore, we observed an extensive mortality of bivalves exposed to the sampled mixtures in the two southernmost sampling stations, while the battery of biomarkers and the results of proteomics have highlighted how the sampled plastic mixtures caused an imbalance in the redox state, already indicated as a classic effect due to plastic exposure, but also an impact on energy stock and on some fundamental cellular pathways always linked to energy metabolism.

Urban flood resilience, a discursive-institutional analysis of planning practices in the Metropolitan City of Milan

Flood risk is increasing all over the globe due to urbanization and the effects of climate change. Water managers and urban planners try to cope with flood risk by enhancing urban flood resilience. Three main discourses of resilience are engineering, ecological, and socio-ecological resilience. Whereas the discourse of engineering resilience emphasizes the use of flood protection infrastructures, the discourses of ecological and socio-ecological resilience advocate river restoration and spatial strategies to reduce flood risk. In this paper, we investigate which resilience discourse is dominant in the Lambro river basin (Metropolitan City of Milan), and how this discourse has been translated into institutions (rules-in-use) and outcomes, such as flood protection infrastructures or building regulations. Our discursive-institutional analysis is informed by the (politicized) Institutional Analysis and Development (IAD) framework, which highlights the role of discursive, institutional, and contextual factors in explaining the outcomes of strategic interactions within action arenas. It is shown that whereas bottom-up initiatives try to foster socio-ecological resilience, the engineering resilience discourse still dominates within the Lambro river basin because national policies and funds are geared towards hard infrastructure measures.

Embryo/larval toxicity and transcriptional effects in zebrafish (Danio rerio) exposed to endocrine active riverbed sediments.

Sediment toxicity plays a fundamental role in the health of inland fish communities; however, the assessment of the hazard potential of contaminated sediments is not a common objective in environmental diagnostics or remediation. This study examined the potential of transcriptional endpoints investigated in zebrafish (Danio rerio) exposed to riverbed sediments in ecotoxicity testing. Embryo-larval 10-day tests were conducted on sediment samples collected from five sites (one upstream and four downstream of the city of Milan) along a polluted tributary of the Po River, the Lambro River. Sediment chemistry showed a progressive downstream deterioration in river quality, so that the final sampling site showed up to eight times higher concentrations of, for example, triclosan, galaxolide, PAH, PCB, BPA, Ni, and Pb, compared with the uppermost site. The embryo/larval tests showed widespread toxicity although the middle river sections evidenced worse effects, as evidenced by delayed embryo development, hatching rate, larval survival, and growth. At the mRNA transcript level, the genes encoding biotransformation enzymes (cyp1a, gst, ugt) showed increasing upregulations after exposure to sediment from further downstream sites. The genes involved in antioxidant responses (sod, gpx) suggested that more critical conditions may be present at downstream sites, but even upstream of Milan there seemed to be some level of oxidative stress. Indirect evidences of potential apoptotic activity (bcl2/bax < 1) in turn suggested the possibility of genotoxic effects. The genes encoding for estrogen receptors (erα, erβ1, erβ2) showed exposure to (xeno)estrogens with a progressive increase after exposure to sediments from downstream sites, paralleled by a corresponding downregulation of the ar gene, likely related to antiandrogenic compounds. Multiple levels of thyroid disruption were also evident particularly in downstream zebrafish, as for thyroid growth (nkx2.1), hormone synthesis and transport (tg, ttr, d2), and signal transduction (trα, trβ). The inhibition of the igf2 gene reasonably reflected larval growth inhibitions. Although none of the sediment chemicals could singly explain fish responses, principal component analysis suggested a good correlation between gene transcripts and the overall trend of contamination. Thus, the combined impacts from known and unknown covarying chemicals were proposed as the most probable explanation of fish responses. In summary, transcriptional endpoints applied to zebrafish embryo/larval test can provide sensitive, comprehensive, and timeliness information which may greatly enable the assessment of the hazard potential of sediments to fish, complementing morphological endpoints and being potentially predictive of longer studies.

A unified framework for the assessment of multiple source urban flash flood hazard: the case study of Monza, Italy

ABSTRACTThis paper aims to analyze the flood hazard in the city of Monza, which periodically suffers from overflows from both the river Lambro and the urban drainage system during wet weather conditions. A unified Urban Flash Flood Model of Monza is therefore developed to capture both sources of hazard. The model is first validated by comparing the results of simulations with historical data related to the area of Monza, then is exploited to obtain maximum flood depth and velocity maps for three different return periods. Overall, the results show the different nature of the flood-related hazard and the sewer-related hazard: the former is concentrated across the rivers whereas the latter spreads patchy over the territory. Furthermore, the former features much larger water levels and flow velocities, which result in more serious hazard to citizens.

Dynamic integrated water quality modelling: A case study of the Lambro River, northern Italy

In this paper an integrated modelling approach is presented and applied to a 26km stretch of the Lambro River downstream of the Merone Wastewater Treatment Plant in northern Italy. The sub-models used (ASM1 for the treatment plant and RWQM1 for the river) have been implemented in the WEST® simulator. Hydraulics and quality processes of the Lambro River have been modelled with a 'tanks in series' approach. The purpose of this study is to model the effect on river water quality of an insufficient treatment capacity of the WWTP. The plant was constantly operating at its maximum hydraulic capacity, leading to a daily bypass of dry weather wastewater, which imposed a marked diurnal cycle on pollutant concentrations in the river. The assessment of the actual WWTP upgrade has confirmed its beneficial effect on the river water quality.

Risk assessment of a mixture of emerging contaminants in surface water in a highly urbanized area in Italy.

A complex mixture of emerging contaminants (ECs) occurs in the environment, with potential effects for aquatic organisms and human health. This study assessed the environmental risk of a mixture of ECs detected in the most urbanized and industrialized area of Italy. Water samples were collected in the Lambro river basin to the north and south of Milan, and were analyzed by liquid chromatography tandem mass spectrometry. The Environmental Risk Assessment (ERA) was performed calculating the Risk Quotients (RQs) for each EC as the ratio of Measured Concentrations (MECs) and Predicted No Effect Concentrations. The ERA was also conducted for the whole mixture of ECs by considering the RQs of the components. The results confirmed that ECs are ubiquitous in urbanized areas. The ERA for the single pollutants identified a panel of substances of environmental concern (estrogens, amoxicillin, clarythromycin, triclosan and nicotine). The ERA for the mixture indicated a potential cumulative risk for the substances that individually could be considered safe, highlighting the importance of taking the whole mixture of ECs into account for the ERA. This information may help establish EU regulations for ECs and environmental quality standards for regulatory purposes.

Phosphorus content in a deep river sediment core as a tracer of long-term (1962–2011) anthropogenic impacts: A lesson from the Milan metropolitan area

Reconstructions of past fluvial contamination through the analysis of deep sediment cores are rarely reported in literature. We examined the phosphorus fractions in a deep (2.6 m) sediment core of the Lambro River downstream of the highly anthropized Milan metropolitan area and upstream of the Po river the main Italian watercourse. The core covered the period 1962–2011. Total phosphorus concentrations resulted typical of a strongly impacted environment (4788 mg P kg DW−1 on average) with the highest concentrations related to the 1960s (7639 mg P kg DW−1) reflecting the period of maximum demographic growth. Afterwards, phosphorus concentrations decreased thanks to the infrastructural and legislative initiatives carried out in the 1980s and the 1990s to reduce the impact of urban point sources. Subsequently, total phosphorus concentrations stabilized on values around 3000 mg P kg DW−1 and did not diminish further, even after the second phase of infrastructural interventions carried out in the second half of the 2000s. This was related to the increasing relative impact of the combined sewer overflows in the sewage system and to the strong phosphorus enrichment of the basin. Most of the phosphorus was in inorganic forms (86% of the total) that have been identified as the final target of the domestic effluent inputs. The contribution of organic phosphorus was lower but constant over the period 1962–2011. It likely originated from the agricultural areas located south of the city of Milan. In conclusion, this study underlines how past interventions have been effective in reducing urban point sources but it also highlights the current difficulties related to the growing importance of other sources influenced by the surface runoff (i.e., combined sewer overflows and agriculture). The study also emphasizes a general phosphorus enrichment of the Lambro River basin and its impact on the Po River and the Adriatic Sea.

Mass balance of emerging contaminants in the water cycle of a highly urbanized and industrialized area of Italy.

The occurrence of several classes of emerging contaminants (ECs) was assessed in the River Lambro basin, one of the most urbanized and industrialized areas of Italy. The study aims were to identify the main sources of ECs, quantify their amounts circulating in the water cycle, and study their fate in the aquatic environment. More than 80 ECs were selected among pharmaceuticals (PHARM), personal care products (PCPs), disinfectants (DIS), illicit drugs (IDs), perfluorinated compounds (PERF), alkylphenols and bisphenol A (Alk-BPA), and anthropogenic markers (AM). Specific analytical methods were developed for quantitative analysis based on solid phase extraction and liquid chromatography tandem mass spectrometry. ECs were measured in rivers upstream and downstream of the main city (Milan), and in untreated and treated wastewater from Milan to assess the contribution to river contamination, and in superficial and deep groundwater in the city area to study the relationship between river and groundwater contamination. Samples were collected in a two-year monitoring campaign. Almost all ECs were ubiquitous in untreated wastewater, at concentrations up to the μg/L range, and the most abundant classes were PHARM and AM. Removals during different wastewater treatment processes were studied and the most stable substances were PHARM, PCPs and PERF. The mass loads increased for all the classes of ECs along the River Lambro basin. A mass balance was done in the river basin and allowed to identify the main sources of contamination, which were domestic, from treated or untreated wastewater, for PHARM, PCPs and IDs, mainly industrial for PERF, and both industrial and domestic for Alk-BPA. The study of AM helped to identify direct discharges of untreated wastewater. A substantial contribution of surface water to groundwater contamination was observed. This study improves the knowledge on occurrence, sources and fate of multiple classes of ECs in a highly urbanized area providing useful information to help the establishment of EU regulations for ECs.

Combined Use of Caffeine and Turbidity to Evaluate the Impact of CSOs on River Water Quality

Several studies have demonstrated that the most effective way to control eutrophication is to reduce phosphorus input at the scale. Water quality monitoring programs need to separately evaluate the different polluting sources to provide a suitable estimate of their relative contributions and thus accurately prioritize possible restoration actions. Urban area cases, where a portion of untreated wastewater is often discharged directly into receiving surface waters by combined sewer overflows (CSOs) during rain events, remain unsolved. In this context, an urban watershed located in Northern Italy with 60 CSOs has been chosen as a case study, and four rainy events have been hourly monitored. The proposed monitoring program consists of the combined use of caffeine and turbidity to estimate the volume and phosphorus load spilled into the river from the CSOs, respectively. Caffeine proved to be a suitable molecule to quantify the volume of wastewater discharged into water bodies, based on a per capita caffeine load of 10.8 mg inhab−1 d−1, estimated in the present work. This research showed that, on average, more than half of the total phosphorus loads transported by the river is due to the CSO discharges (56.5%). The knowledge of the prevailing responsibility of the CSO discharges for the Lambro River quality allows prioritizing effective restoration actions.

Viromes As Genetic Reservoir for the Microbial Communities in Aquatic Environments: A Focus on Antimicrobial-Resistance Genes.

Despite studies of viromes isolated from aquatic environments are becoming increasingly frequent, most of them are limited to the characterization of viral taxonomy. Bacterial reads in viromes are abundant but the extent to which this genetic material is playing a role in the ecology of aquatic microbiology remains unclear. To this aim, we developed of a useful approach for the characterization of viral and microbial communities of aquatic environments with a particular focus on the identification of microbial genes harbored in the viromes. Virus-like particles were isolated from water samples collected across the Lambro River, from the spring to the high urbanized Milan area. The derived viromes were analyzed by shotgun metagenomic sequencing looking for the presence, relative abundance of bacterial genes with particular focus on those genes involved in antimicrobial resistance mechanisms. Antibiotic and heavy metal resistance genes have been identified in all virome samples together with a high abundance of reads assigned to cellular processes and signaling. Virome data compared to those identified in the microbiome isolated from the same sample revealed differences in terms of functional categories and their relative abundance. To verify the role of aquatic viral population in bacterial gene transfer, water-based mesocosms were perturbed or not perturbed with a low dose of tetracycline. The results obtained by qPCR assays revealed variation in abundance of tet genes in the virome and microbiome highlighting a relevant role of viral populations in microbial gene mobilization.

Lipid classes and fatty acids composition of the roe of wild Silurus glanis from subalpine freshwater

The fat content and the fatty acid composition of the roe of European catfish (Silurus glanis) wild specimens captured in the Lambro river basin (Como, Northern Italy) were investigated in order to assess their nutritional value. Total extracted lipid values on roe weight were 5.8–6.3%. Phospholipids (40.2–43.6%) and triacylglycerols (31.8–34.7%) were the most represented lipid classes. Relevant amount of cholesteryl esters (14.3–15.6%) were also detected. The main fatty acids were palmitic, oleic and cis-4,7,10,13,16,19-docosahexaenoic acid (DHA). Total saturated fatty acids were 28.1–30.9%, monounsaturated fatty acids were 28.2–30.6%, and polyunsaturated fatty acids (PUFAs) were 26.7–29.1%. The good found content of phospholipids and ω3-polyunsaturated fatty acids encourage further investigation for the exploitation of Silurus glanis roe in food products and/or supplements.

Medium- and Long-Term Effects of Estrogenic Contaminants on the Middle River Po Fish Community as Reconstructed from a Sediment Core.

Recent studies showed that endocrine active compounds (EDs) capable to induce fish gonadal histopathologies, plasma vitellogenin and thyroid disruption, are transported by the River Lambro to the River Po, potentially affecting the fish community of the main Italian river. To assess whether fish relative abundance, composition and health were impaired by the River Lambro, a 3-year survey was undertaken in the main river. Results showed that the tributary supports in the River Po a denser fish community (+43%), with a higher total biomass (+35%). The survey also showed niche- and sensitivity-dependent effects, so that three benthopelagic species (bleak, topmouth gudgeon, and bitterling) were, for example, more abundant downstream from the tributary (up to 3.4×), but their sizes were significantly smaller. The present fish community was then compared with that described 30 years before in the same area of the Po River. This comparison highlighted that some fish species have disappeared and many have severely declined. To better evaluate this contrast, a sediment core of the Lambro tributary was analysed for the time trends of natural estrogens (E1, E2, E3), bisphenol A and alkylphenols. The results showed that during the last 50 years the River Lambro has been exposed to high estrogenic activities (16.1 ± 9.3 ng E2 equivalents/g), which inevitably affected also the River Po. In addition, at the time of the previous survey, six species of the main river had skewed sex ratios toward all-female populations, providing evidence that EDs and particularly (xeno)estrogens were already affecting the long-term viability of fish populations. Estrogens thus can be ascribed among the causal factors of fish qualitative and quantitative decline of the River Po, although long-term effects have been likely mitigated by nonconfinement of fish populations and nutrient enrichment.

Exposing native cyprinid (Barbus plebejus) juveniles to river sediments leads to gonadal alterations, genotoxic effects and thyroid disruption

Juveniles (50 days post hatch) of a native cyprinid fish (Barbus plebejus) were exposed for 7 months to sediments from the River Lambro, a polluted tributary impairing the quality of the River Po for tens of kilometers from their confluence. Sediments were collected upstream of the city of Milan and downstream at the closure of the drainage basin of the River Lambro. Chemical analyses revealed the presence of a complex mixture of bioavailable endocrine-active chemicals, with higher exposure levels in the downstream section of the tributary. Mainly characterized by brominated flame retardants, alkylphenols, polychlorinated biphenyls, and minor co-occurring personal care products and natural hormones, the sediment contamination induced reproductive disorders, as well as other forms of endocrine disruption and toxicity. In particular, exposed male barbel exhibited higher biliary PAH-like metabolites, overexpression of the cyp1a gene, vitellogenin production in all specimens, the presence of oocytes (up to 22% intersex), degenerative alterations in their testis, liver fat vacuolization, a marked depression of total thyroxine (T4) and triiodothyronine (T3) plasma levels, and genotoxic damages determined as hepatic DNA adducts. These results clearly demonstrate that Lambro sediments alone are responsible for recognizable changes in the structure and function of the reproductive and, in general, the endocrine system of a native fish species. In the real environment, exposure to waterborne and food-web sources of chemicals are responsible for additional toxic loads, and the present findings thus provide evidence for a causal role of this tributary in the severe decline observed in barbel in recent decades and raise concern that the fish community of the River Po is exposed to endocrine-mediated health effects along tens of kilometres of its course.