E. Speranza

Risk ranking of multiple-POPs in detritivorous fish from the Río de la Plata

To evaluate the bioaccumulation and the risk associated to consumption of lipid-rich detritivorous fish, a comprehensive set of organic pollutants (n=213) including polychlorinated biphenyls (PCBs), dioxin like PCBs (dlPCBs), chlorinated pesticides (CHLPs), chlorobenzenes (CBzs), polybrominated diphenyl ethers (PBDEs), polychlorinated dibenzo dioxins and furans (PCDD/F), resolved (ALI) and unresolved aliphatic hydrocarbons (UCM) and linear alkyl benzenes (LABs) were analyzed in Sábalo fish (Prochilodus lineatus) collected in the polluted Metropolitan Buenos Aires coast and in migrating specimens. Fatty fish muscles (lipids: 74±9.3% dry weight) contained homogeneous (24-51% variability) and very high-concentrations of organic pollutants ranging from 60 to 1,300 μg g(-1) fresh weight (fw) ALI+UCM; 10-40 μg g(-1) fw LABs and PCBs; 0.1-1 μg g(-1) fw dlPCBs, DDTs, chlordanes, CBzs and PBDEs; 0.01-0.1 μg g(-1) fw mirex, endosulfans, aldrin, dieldrin, endrin and 0.07-0.2 ng g(-1) PCDD/F. Total toxicity equivalents (TEQs) ranged from 60 to 395 pg g(-1) fw (34±17 and 213±124 pg g(-1) TEQs for PCDD/F and dlPCBs respectively). These are among the highest concentrations reported for fish and point out the remarkable ability of Sábalo to feed on anthropogenic organic-enriched particles and tolerate a high pollutant load. Contaminant signatures show partial alteration with still abundant lower molecular weight components indicating that fish feeds directly in the outfalls. Consumption limits based on reference doses ranged from 0.1 (PCBs) to >1,2000 g d(-1) (endosulfan) allowing a comprehensive risk-based ranking of contaminants in this long-range migrating, detritivorous fish.

Migratory behaviour of a dominant detritivorous fish Prochilodus lineatus evaluated by multivariate biochemical and pollutant data

This paper studies the migration pathways and ranges of a dominant detritivorous fish Prochilodus lineatus along pollution gradients in the Río de la Plata basin using multivariate analysis of biochemical and pollutant data. Biochemical composition (water, ash, lipids, proteins, carbohydrates, neutral lipids classes and fatty acids), aliphatic hydrocarbons (ALI), polychlorinated biphenyls (PCB), linear alkylbenzenes (LAB) and organochlorine pesticides (OClP) were determined in muscle samples of P. lineatus collected in Metropolitan Buenos Aires, the lower Paraná River (Paraná: 200-1000 km from Buenos Aires) and the middle Paraná and Paraguay Rivers (North: 1000-1400 km north). Biochemical variables and pollutants exhibited large variability [Lipids 1.1-89.5% wet mass; ALI 1.4-413; LABs not detectable (n.d.)-115.2; PCBs n.d.-27.9; OClPs n.d.-11.8 µg g(-1) dry mass], due to the contrast of Buenos Aires with North fish. Fish from Buenos Aires were fatty (lipids 24.7 ± 12.3% wet mass), enriched in 18 carbon fatty acids and severely contaminated (ALI 152.4 ± 72.3; LABs 65.1 ± 26.4; PCBs 15.2 ± 6.8; OClPs 1.8 ± 1.9 µg g(-1) dry mass mean ±S.D.). In contrast, fish from North were lean (4.1 ± 3.1% wet mass), enriched in long chain (>20 carbons) polyunsaturated fatty acids, with average one to two orders of magnitude lower pollutant levels (ALI 41.2 ± 51.9; PCBs 2.2 ± 3.5; LABs 8.8 ± 21.1; OClPs 0.67 ± 0.75 µg g(-1) dry mass mean ±S.D.). Paraná showed intermediate values in all variables, denoting the mixing of different fish stocks. Based on principal component analysis, 14 outliers from 60 North and Paraná samples (representing 26 from 108 individual fish) were identified as pertaining to the Buenos Aires group with very similar lipid and pollutant levels. Data suggest that P. lineatus migrates a highly variable distance, exceeding 800-1000 km in multiple spatial and temporal overlapping ranges. Chemometric analysis of biochemical and pollutant data effectively discriminates fish according to the chemical signature acquired by detritus feeding in pristine and contaminated urban or industrial areas.

Seasonal and inter-annual variability of water quality in the Uruguay River, Argentina

Abstract Water quality of the Uruguay River was evaluated with multi-parametric (temperature, turbidity, conductivity, pH, dissolved oxygen) and sediment trap data (particle flux, total organic carbon and nitrogen contents) and correlated to precipitation, river discharge and El Niño Southern Oscillation (ENSO) indices for the period 2006–2011. Hydro-meteorological parameters averaged 24–85% variability with coincident precipitation (200–400 mm month-1), discharge (7000–28 000 m3 s-1) and turbidity peaks (50–80 NTU) in the austral spring, and absolute maxima during the El Niño 2009 episode. Spectral analysis of discharge and sea-surface temperature anomaly (SSTA) showed consistent variance maxima at approx. 3 and 1.5 years. Deseasonalized discharge was significantly correlated to SSTA. During river floods, pH decreased (from 7.5 to 6.6) and particle dynamics peaked (turbidity: 15–80 NTU; vertical fluxes: 20–200 g m-2 d-1; total solid load: <1000 to 100 000 t d-1),whereas TOC remained stable (3.2 ± 0.8%) and C/N ratios increased (10–12) due to the higher contribution of terrestrial detritus.

Fatty acid alterations in the detritivorous Prochilodus lineatus promoted by opportunistic feeding on sewage discharges in the Río de la Plata estuary

Muscle fatty acid profiles and PCB contents of the detritivorous species Prochilodus lineatus and its diet (stomach contents, settling particles and sediments) were analysed from reference and polluted areas of the Paraná-Rio de la Plata basin, to evaluate the alterations produced by opportunistic feeding on sewage discharges. Overall muscle fatty acid composition was dominated by saturated and monounsaturated 16 and 18 carbon (18 C-FA) components with reduced long-chain polyunsaturated fatty acids (LC-PUFA). Compared to sediments, settling particles and stomach contents were enriched in lipids and had a similar fatty acid composition. Opportunistic feeding on sewage detritus at Buenos Aires resulted in enhanced PCB and triglyceride accumulation, with higher proportions of 18 C-FA and lower proportions of 16:1 and LC-PUFA compared to fish from northern pristine reaches of the basin. Mid-Paraná showed intermediate values reflecting mixing of the North stock with migrating Buenos Aires P. lineatus identified by their lipid and contaminant profile. According to multivariate analyses, this geographical variation of fatty acid composition was strongly influenced by PCB concentration. Prochilodus lineatus assimilates the energy subsidy of sewage inputs through enhanced lipogenesis with dominant 18 C-FA and significant amounts of valuable LC-PUFA. This lipid alteration facilitates the bioaccumulation of PCBs which in turn may reinforce the adipogenic effect of sewage feeding.

Long-Term (1970–2017) Temporal Trends of Polychlorinated Biphenyls in Fish, Settling Material, and Sediments from Populated and Remote Sites in Río de la Plata Estuary, Argentina

Temporal trends of polychlorinated biphenyls (PCBs) were studied for detritivorous fish (1996-2017) and settling material (2002-2017) from polluted Buenos Aires coast and for a dated sediment core (1970-2013) from the outer Río de la Plata estuary. In spite of contrasting concentrations [5.3 ± 6.3 μg·g-1 dry weight (dw) for fish, 48 ± 26 ng·g-1 dw for settling material, and 1.5 ± 0.7 ng·g-1 dw for core], all three revealed exponentially decreasing trends over time (97%, 83%, and 83%, respectively). Time trends showed peak maxima coincident with Argentinas period of maximum PCB usage in 1973-1980 (80 cm depth in the core) and pulse discharges related to PCB banning in 2001-2002 (fish) with a lighter signature enriched in less persistent tri- and tetrachlorobiphenyls. The log-linear PCB time trends compare well with the predicted decrease for a high emission scenario from global emission data; the best fit was observed for the less impacted sediment core (-2%·year-1 versus -3%·year-1 for emission scenario). Steeper slopes are observed for the more polluted settling material (-5%·year-1) and especially for fish, in which the background decline trend tripled after the 2001 PCB pulse (from -7%·year-1 to -21%·year-1). These PCB time trends in related environmental compartments from contrasted sites provide rare evidence for evaluating the effectiveness of control measures in southern South America.