The use of biomimetic tools for water quality monitoring: passive samplers versus sentinel organisms.

To evaluate the performance of artificial and biological integrative sampling strategies, dissolved concentrations of polychlorinated biphenyl (PCBs) and metals (Cu and Mn) were measured with passive sampler devices (PSD) enclosing hydrophobic and chelating phases, and Asiatic clams were transplanted to a polluted area in the Rio de la Plata. Water concentrations based on PSD were compared with spot water samples collected at 0, 15, 32, and 63 days of exposition. PCBs and metals displayed linear accumulation kinetics both in PSDs and bivalves, but with different slopes. PCBs slopes were 2-27 times higher in bivalves (0.3-7.9 vs. 0.1-2.6 ng g-1 d-1 in PSDs) reflecting active filtration and uptake from particles, colloids, and dissolved phase, whereas metal slopes were 2.5-11 times lower in bivalves (0.04-0.18 vs. 0.10-2.00 µg g-1 d-1 in PSDs) suggesting metal bioregulation. Truly dissolved PCB concentrations from PSD (4.0-6.9 ng.l-1) represented average 13±4 % of PCB concentrations from filtered spot water samples reflecting the operational discrimination of the PSD diffusion membrane on competing dissolved and colloidal organic phases. In contrast, PSD dissolved Cu concentrations (2.3-8.2 µg l-1) were equivalent to the spot water values (3.2-3.8 µg l-1) suggesting that Cu speciation was adequately integrated by passive sampling. On the other hand, PSD-dissolved Mn concentrations (49±38 µg l-1) were higher (p<0.05) than those from spot water samples (7±11µg l-1) possibly due to phase changes of Mn distribution related to variable redox conditions in the water. Results evidenced that the PSDs are efficient accumulators of metals and organic compounds from the truly dissolved fraction.

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.

Behavior of dioxin like PCBs and PBDEs during early diagenesis of organic matter in settling material and bottom sediments from the sewage impacted Buenos Aires' coastal area, Argentina.

Settling particles (SPs) and sediments collected in the Buenos Aires sewer area were analyzed for dioxin like polychlorinated biphenyls (dlPCBs) and polybrominated diphenyl ethers (PBDEs) to follow early diagenetic changes during transport and deposition of organic matter. SP showed a temporal trend of higher total organic carbon (TOC) and fresher dlPCBs and PBDEs signatures during warm-rainy months related to more efficient washout of residues. TOC-normalized sediment trap concentrations suggest a diagenetic magnification of dlPCBs during cold-dry months due to enhanced decomposition of TOC, whereas most labile PBDEs appear to follow TOC decay. The diagenetic behavior of individual congeners along seasonal changes (cold/warm) and during deposition (bottom sediment/SP) shows the selective preservation of heavier, more persistent congeners with a positive relationship with sediment half-lives. The 3-4 times diagenetic magnification of heavier congeners observed in bottom sediments would be a prevailing long-term pathway for dlPCBs and PBDEs bioaccumulation in detritus feeding organisms.

Trace metals in settling particles from the sewage impacted Buenos Aires coastal area in the Río de la Plata estuary, Argentina.

Sediment traps deployed in Buenos Aires sewage outfall area collected a substantial amount of material (average mass flux 22 ± 12 g cm (2) year(-1)) with very high metal concentrations, mostly in the range of hazardous exposition for organisms (Zn: 138-671, Cu: 41-273, Cr: 44-255 and Pb: 26-260 µg g(-1)). The combination of high mass fluxes and concentrations results in huge metal fluxes (0.005-0.7 to 3.6-31 g m(-2) day(-1) for minor elements and Fe, respectively). Metal concentrations were correlated to the total mass flux and total organic carbon but with different trends for redox-sensitive Fe and Mn (negative) and anthropogenic elements (positive). This reflects the key role of organic discharges promoting anoxia with Fe and Mn evasion, and also contributing toxic metals.

High-resolution multivariate analysis of the hydrochemical signature of water corridors in the upper Río de la Plata estuary, Argentina.

Major world river-estuaries integrate the hydrochemical characteristics of the basin with specific signatures which are maintained until complete mixing or discharge to the sea. The chemical signature of distinct water masses and the anthropogenic impact in the Upper Río de la Plata estuary (RLP) were evaluated by high-resolution continuous monitoring (i.e. every 200 m) of conductivity, turbidity, pH, temperature, chlorophyll a and coloured dissolved organic matter (CDOM), discrete analysis of suspended particulate matter (SPM) grain size composition combined with multivariate analysis (K-means clustering, Principal Component Analysis). The characteristic signatures of main RLP tributaries such as the Paraná River, yielding higher conductivity, CDOM, turbidity and coarser SPM, and the Uruguay River, with clearer, more eutrophic waters enriched in very fine SPM, were maintained 60 km seaward from the estuary head. Across the river, three water corridors with distinct signatures and variable widths (3-20 km) were identified reflecting the transition from Paraná to Uruguay River waters. Multivariate techniques also allowed the identification of a polluted coastal corridor (higher conductivity and CDOM and lower turbidity) impacted by wastewater discharges from the metropolitan Buenos Aires and La Plata cities extending 100 km seaward. The combined strategy of high-resolution monitoring, discrete sampling and multivariate techniques was a useful tool to identify water masses, corridors of flow and anthropogenic sources in a heavily urbanized estuary.

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.

Biochemical composition of a dominant detritivorous fish Prochilodus lineatus along pollution gradients in the Paraná-Río de la Plata Basin.

The biochemical composition of muscle, liver and stomach contents of a detritivorous fish Prochilodus lineatus was analysed and compared to settling particles and sediments along pollution gradients over 1500 km of the Río de la Plata Basin to evaluate the effects of anthropogenic discharges in a detritus food chain. The stomach contents of P. lineatus collected in the polluted Metropolitan Buenos Aires coast were enriched in proteins, carbohydrates and lipids, similar to settling particulates collected in the sewer area, and two to five times higher than underlying sediments, supporting the interpretation that P. lineatus feeds on unconsolidated organic flocs freshly decanted from mixed industrial and sewage outfalls. Fish from Buenos Aires had consistently higher standard length (L(S)) and mass (M(T)) slopes (b = 3.5), condition indexes (K = 3.01 +/- 0.47, mean +/-s.d.) and muscle fat content (fat = 23.8 +/- 13.8% wet mass, mean +/-s.d.) relative to northern fish (b = 2.7, K = 2.22 +/- 0.39, fat = 3.4 +/- 3.2% wet mass, respectively), suggesting that sewage-derived organic matter was an enriched diet, which allowed an enhanced body mass gain and fat accumulation compared to organic-poor vegetal detritus in the north Paraná area. Buenos Aires fish also showed higher hepato-somatic indices (mean +/-s.d. I(H) 1.41 +/- 0.49 v. 0.70 +/- 0.32, respectively), which correlated with their two to three orders of magnitude higher hydrocarbon and polychlorinated biphenyl (PCB) loads, suggesting an enhanced detoxifying metabolism. The northward migration of fatty P. lineatus was evidenced by the presence of clear outliers in the L(S) and M(T) relationship, K and fat content along the Paraná River.

Vertical fluxes and accumulation of trace metals in superficial sediments of the Río de la Plata estuary, Argentina.

Superficial sediments and settling material collected in Buenos Aires coastal area were analyzed to evaluate the accumulation and sources of trace metals. Residual elements showed homogeneous sedimentary concentrations (Fe: 23,846 +/- 4,367; Ni: 10 +/- 2.7; Mn: 706 +/- 314 µg g(-1)) whereas anthropogenic metals presented exponentially decreasing offshore gradients (Zn: 98 +/- 69; Cr: 28 +/- 21; Cu: 19 +/- 15; Pb: 18 +/- 13 µg g(-1)). Anthropogenic impact was evaluated through metal-Fe relationships, Fe-normalized enrichment factors and sediment quality guidelines. The slopes of metal-Fe regressions from background sites were comparable to upper crust metal ratios, excepted Cr which is impoverished, and Mn which is diagenetically enriched. Metal-Fe relationships also hold for most 2.5 km offshore sites but with higher slopes denoting human influence, and are completely lost in 1-2.5 km sediments and trap material which plot over the regressions and exceed sediment quality guidelines.

Bioaccumulation of anthropogenic contaminants by detritivorous fish in the Río de la Plata estuary: 2-Polychlorinated biphenyls.

The temporal variability and bioaccumulation dynamics of individual PCBs were studied in a detritivorous fish (Sábalo: Prochilodus lineatus) collected from 1999 to 2005 in the polluted Buenos Aires coastal area. Fish muscles contain high concentrations of total PCBs (11+/-7.2, 4.6+/-3.4 or 19+/-13 microg g(-1), dry, fresh and lipid weight, respectively) reflecting chronic bioaccumulation from sewage-industrial particulates. On a temporal basis, lipid normalized PCBs concentrations peaked by the end of 2001-2002 coincident with the rainiest period over the last four decades and shortly after PCB prohibition in the country, reflecting massive discharges to the coastal ecosystem. PCB composition in fish muscles show a prevailing contribution of hexachlorobiphenyls (35+/-4.2%), followed by hepta (23+/-3.0%), penta (20+/-3.6%), tri-tetra (16+/-4.8%) and minor proportions of octa-decachlorobiphenyls (5.7+/-3.1%) similar to an Aroclor 1242-1254-1260 1:2:4 mixture. During 2001-2002 maxima fish showed an enrichment in tri-tetrachlorobiphenyls ( approximately 1242-1254-1260 1:1:1 mixture) denoting a fresher signature. Fish/settling material lipid-organic carbon accumulation factors (BSAFs: 2.4-46, average: 21+/-10) plotted against kow showed a parabolic trend (BSAFs=-0.38 log kow2 + 5.16 log kow -15.85; R2=0.46) maximizing at hexa, hepta and octachlorobiphenyl 203 with reduced bioaccumulation of a few hepta (170, 191) and most octa-decachlorobihenyls suggesting limited intestinal absorption.

Bioaccumulation of anthropogenic contaminants by detritivorous fish in the Río de la Plata estuary: 1-aliphatic hydrocarbons.

The temporal variability and bioaccumulation dynamics of C(12-25)n-alkanes, isoprenoids and unresolved aliphatic hydrocarbons (UCM) were studied in a detritivorous fish (Sábalo: Prochilodus lineatus) collected from 1999 to 2005 in the sewage impacted Buenos Aires coastal area. Fish muscles contain huge amounts of n-C(12-25) (165+/-93, 70+/-48 or 280+/-134 microg g(-1), dry, fresh and lipid weight, respectively) and UCM (931+/-560, 399+/-288 and 1,567+/-802 microg g(-1)) reflecting the chronic bioaccumulation of fossil fuels from sewage particulates. On a temporal basis, lipid normalized aliphatic concentrations peaked by the end of 2001-2002 during the rainiest period over the last four decades (1,750 vs. 1,083+/-4.6mm in 1999, 2004 and 2005), reflecting an enhanced exposition due to massive anthropogenic fluxes from Metropolitan Buenos Aires in wet years. The hydrocarbon composition in fish muscles is enriched in n-C(15-17) and isoprenoids relative to a fresh crude oil and settling particulates, with fresher signatures during the 2001-2002 maxima. Fish/settling material bioaccumulation factors (BAFs: 0.4-6.4 dry weight or 0.07-0.94 lipid-organic carbon) plotted against K(ow) showed a parabolic pattern maximizing at n-C(14-18) and isoprenoids. The optimal bioaccumulation window corresponds to highly hydrophobic (log K(ow): 7.2-9.9), intermediate-size C(14-18)n-alkanes and C(15-20) isoprenoids (MW: 198-282; length: 17.9 to 25.4A) with melting points ranging from -19.8 to 28 degrees C. The uptake efficiency is inversely correlated to melting points and increased from 75% for n-C(25) to above 90% for n-C(14-15) and isoprenoids.

Rb-Cs ratio as an indicator of fish diet in lakes of the Patagonia, Argentina.

The ratios of Rb to Cs contents were studied in five fish species from seven lakes located in the Patagonia Andean Range, Argentina in order to trace fish diet. The species studied were native velvet catfish (Diplomistes viedmensis) and creole perch (Percichthys trucha), and exotic brown trout (Salmo trutta), rainbow trout (Oncorhynchus mykiss), and brook trout (Salvenilus fontinalis). Rainbow trout specimens from two farms were also studied, as well as fish food items and native mussels (Diplodon chilensis). Rb and Cs concentrations were determined by instrumental neutron activation analysis. A positive correlation of Cs concentration in the muscle of velvet catfish with fish length was observed, probably associated with the long biological half-life of this element in this species, whereas the Rb concentration remained constant, hence inhibiting the use of Rb-Cs ratios as a tracer in this case. Seasonal variations observed for rainbow trout and Cs concentration background bias in one of the lakes studied are also a limiting factor to the use of Rb-Cs ratios as a diet tracer. Rb-Cs ratios allowed clear differentiation of rainbow trout raised in farms from the natural specimens that lived in the same environment, in agreement with Rb-Cs ratios determined in both diets. Rb-Cs ratios in rainbow trout showed significant differences between Rivadavia and Futalaufquen lakes compared to Moreno and Nahuel Huapi lakes, which could be associated with a higher participation of plankton in the diet in the first case. No relevant variations in Rb-Cs ratios of brown trout were observed, probably because of the similarity in the diet.

Airborne PCDD/F profiles in rural and urban areas of Buenos Aires Province, Argentina.

Passive air samplers were deployed in 18 rural and urban locations in the densely populated Buenos Aires district to investigate airborne polychlorinated dibenzo-p-dioxin and polychlorinated-dibenzofuran (PCDD/Fs) profiles, sources and spatial patterns. Atmospheric concentrations reported as total toxic equivalents (TEQs), 2378-substituted (∑17PCDD/F) and 4-8 homologous groups (∑4-8PCDD/F) were highly variable and significantly correlated to urban scale. The rural average (3.0±2.7fgTEQm-3) was thirty times less than metropolitan values (90±51fgTEQm-3), with urban cluster (5.4±4.0fgTEQm-3) and urbanized area (33±50fgTEQm-3) in an intermediate position. A rural outlier exhibited the highest TEQ values (295-296fgTEQm-3) suggesting a local source. Principal component analyses (PCA) performed for ∑17PCDD/F and ∑4-8PCDD/F to identify source contributions showed more significant results for homologue groups compared to 17 congeners (83 and 45% of total variability explained, respectively) pointing to dominant diesel emissions enriched in TeCDF in rural areas, and open burning and industrial sources characterized by TeCDD, PeCDD contributing most in urbanized and metropolitan areas. Homologue group PCA also performed better clustering samples according to sources and TEQ concentrations. The PCDD/Fs profile of the rural outlier dominated by HxCDF and HpCDD/F showed a typical municipal incineration signature confirming the presence of local source.

Oil spill in the Rio de la Plata estuary, Argentina: 2-hydrocarbon disappearance rates in sediments and soils.

The 6-month assessment of the oil spill impact in the Rio de la Plata described in the preceding paper [Colombo, J.C., Barreda, A., Bilos, C., Cappelletti, N., Demichelis, S., Lombardi, P., Migoya, M.C., Skorupka, C., Suarez, G., 2004. Oil spill in the Rio de la Plata estuary, Argentina: 1 - biogeochemical assessment of waters, sediments, soils and biota. Environmental Pollution] was followed by a 13- and 42-month campaigns to evaluate the progress of hydrocarbon decay. Average sediment hydrocarbon concentrations in each sampling include high variability (85-260%) due to contrasting site conditions, but reflect a significant overall decrease after 3 years of the spill: 17 +/- 27, 18 +/- 39 to 0.54 +/- 1.4 microg g(-1) for aliphatics; 0.44 +/- 0.49, 0.99 +/- 1.6 to 0.04 +/- 0.03 microg g(-1) for aromatics at 6, 13 and 42 months, respectively. Average soil hydrocarbon levels are 100-1000 times higher and less variable (61-169%) than sediment values, but display a clear attenuation: 3678 +/- 2369, 1880 +/- 1141 to 6.0 +/- 10 microg g(-1) for aliphatics and 38 +/- 26, 49 +/- 32 to 0.06 +/- 0.04 microg g(-1) for aromatics. Hydrocarbon concentrations modeled to first-order rate equations yield average rate constants of total loss (biotic+abiotic) twice as higher in soils (k = 0.18-0.19 month(-1)) relative to sediments (0.08-0.10 month(-1)). Individual aliphatic rate constants decrease with increasing molecular weight from 0.21 +/- 0.07 month(-1) for isoprenoids and n-C27, similar to hopanes (0.10 +/- 0.05 month(-1)). Aromatics disappearance rates were more homogeneous with higher values for methylated relative to unsubstituted species (0.17 +/- 0.05 vs. 0.12 +/- 0.05 months(-1)). Continued hydrocarbon inputs, either from biogenic (algal n-C15,17; vascular plant n-C27,29) or combustion related sources (fluoranthene and pyrene), appear to contribute to reduced disappearance rate. According to the different loss rates, hydrocarbons showed clear compositional changes from 6-13 to 42 months. Aliphatics disappearance rates and compositional changes support an essentially microbiologically-mediated recovery of coastal sediments to pre-spill conditions in a 3-4 year period. The lower rates and more subtle compositional changes deduced for aromatic components, suggest a stronger incidence of physical removal processes.

Oil spill in the Rio de la Plata estuary, Argentina: 1. Biogeochemical assessment of waters, sediments, soils and biota.

Aliphatic (ALI) and aromatic (ARO) hydrocarbon concentrations, composition and sources were evaluated in waters, sediments, soils and biota to assess the impact of approximately 1000 tons of oil spilled in Rio de la Plata coastal waters. Total ALI levels ranged from 0.4-262 microg/l in waters, 0.01-87 microg/g in sediments, 5-39 microg/g in bivalves, 12-323 microg/g in macrophytes to 948-5187 microg/g in soils. ARO varied from non-detected 10 microg/l, 0.01-1.3 mug/g, 1.0-16 microg/g, 0.5-6.9 microg/g to 22-67 microg/g, respectively. Offshore (1, 5, 15 km) waters and sediments were little affected and contained low background hydrocarbon levels reflecting an effective wind-driven transport of the slick to the coast. Six months after the spill, coastal waters, sediments, soils and biota still presented very high levels exceeding baseline concentrations by 1-3 orders of magnitude. UCM/resolved aliphatic ratio showed a clear trend of increasing decay: coastal waters (3.3) < macrophytes (6.7) < soils (9.4) < offshore sediments (13) < coastal sediments (17) < clams (52). All environmental compartments consistently indicated that the most impacted area was the central sector close to Magdalena city, specially low-energy stream embouchures and bays which acted as efficient oil traps. The evaluation of hydrocarbon composition by principal component analysis indicated the predominance of biogenic (algae, vascular plant cuticular waxes), background anthropic, pyrogenic and diagenetic hydrocarbons, offshore and in non-impacted coastal sites. In contrast, polluted stations presented petrogenic signatures characterized by the abundance of isoprenoids, low molecular weight n-alkanes and methylated aromatics in different stages of alteration. The petrogenic/biogenic ratio ( n-C23) and petrogenic/pyrogenic relationship (methylated/unsubstitued PAH) discriminated the samples according to the different degree of impact. The following paper present the results of the study of the progress of hydrocarbon disappearance in sediments and soils 13 and 42 months after the spill.

Vertical fluxes and accumulation of PCBs in coastal sediments of the Río de la Plata estuary, Argentina.

Settling particles and underlying sediments collected at 1, 2.5 and 4 km along offshore transects in the urbanized sector of the Río de la Plata were analyzed to evaluate the sources and accumulation of PCBs. Total PCB concentrations range from <0.1 to 100 ng g(-1) and include variability associated to North-South and offshore gradients reflecting the impact of coastal discharges. Highest concentrations were recorded in the industrialized Central area close to Buenos Aires (61+/-37 ng g(-1) at 1 km) relative to cleaner northern stations (3.6+/-2.2 ng g(-1)) and southward sites (37+/-2.8 ng g(-1)), affected by transport of particulate PCBs by coastal currents. Sediment traps deployed in the Central area revealed large depositional fluxes of total matter (361+/-124 gm(-2)day(-1)) and PCBs (26+/-19 microg m(-2)day(-1)) and high sedimentation rates (5.0+/-1.7 cm yr(-1)). Uniform PCB concentrations (66-89 ng g(-1)) down to 20 cm in sediment cores suggest continued PCB discharges during the last 4 years. PCB composition was dominated by hexa (43+/-6.4%), hepta (23+/-5.1%) and pentachlorobiphenyls (21+/-5.5%) with lower proportions tri-tetra (7.4+/-5.4%) and higher chlorinated congeners (5.1+/-3.3%). A consistent weathering pattern with loss of 3-5 chlorobiphenyls and enrichment in higher chlorinated PCBs corresponding to a shift from a 1:1 to a 1:3 1254:1260 Aroclor mixture, was observed offshore. A principal component analysis performed with the relative contribution of PCB congener classes confirmed the offshore weathering pattern indicating that transformer oils containing Aroclor 1254-1260 are the most probable sources. Sediment inventories, sediment trap fluxes and Fugacity II calculations indicate an accumulation approximately 500-800 kg PCB in superficial sediments of this coastal environment.

Bioaccumulation of dioxin-like PCBs and PBDEs by detritus-feeding fish in the Rio de la Plata estuary, Argentina.

A comparative analysis of bioaccumulation behavior of dioxin-like polychlorinated biphenyls (dlPCBs) and polybrominated biphenyl ethers (PBDEs) was conducted involving simultaneous measurements in settling particles and a detritivorous fish (Sabalo, Prochilodus linneatus) collected in the sewage impacted Buenos Aires coastal area. Focalization of dlPCBs and PBDEs along the detritus food chain is reflected by a 30-40-fold increase of dry weight PBDE and dlPCB concentrations from settling particles to fish (1.8 ± 1.0 to 58 ± 31 and 6.8 ± 3.9 to 281 ± 155 ng g(-1) dry weight (dw), respectively). In this transference, dlPCB congeners presented more conservative patterns than those of PBDEs, basically due to debromination of BDE 99 and 153 to BDE 47 in fish. Lipid/organic carbon-based biota-sediment accumulation factors (BSAFs) ranged between 5 and 20 (7.3 ± 3.0 and 16 ± 8.0 for PBDEs and dlPCBs). Congener-specific BSAF of dlPCBs suggested a lower bioavailability of more planar non-ortho-PCB versus mono-ortho-PCB suggesting higher affinity to organic matter. BSAFs of PBDEs differed markedly among bromine homolog groups, supporting the biotransformation-formation from higher brominated to lighter congeners. The log BSAFs-log K OW relationship of dlPCBs and PBDEs presented a parabolic pattern maximizing at log K OW 6-7, but PBDE curve differs reflecting biotransformation processes.

Biodegradation of aliphatic and aromatic hydrocarbons by natural soil microflora and pure cultures of imperfect and lignolitic fungi.

The biodegradation of aliphatic and aromatic hydrocarbons by natural soil microflora and seven fungi species, including imperfect strains and higher level lignolitic species, is compared in a 90-day laboratory experiment using a natural, not-fertilized soil contaminated with 10% crude oil. The natural microbial soil assemblage isolated from an urban forest area was unable to significantly degrade crude oil, whereas pure fungi cultures effectively reduced the residues by 26-35% in 90 days. Normal alkanes were almost completely degraded in the first 15 days, whereas aromatic compounds (phenanthrene and methylphenanthrenes) exhibited slower kinetics. Aspergillus terreus and Fusarium solani, isolated from oil-polluted areas, produced the more efficient attack of aliphatic and aromatic hydrocarbons, respectively. Overall, imperfect fungi isolated from polluted soils showed a somewhat higher efficiency, but the performance of unadapted, indigenous, lignolitic fungi was comparable, and all three species, Pleurotus ostreatus, Trametes villosus and Coriolopsis rigida, effectively degraded aliphatic and aromatic components. The simultaneous, multivariate analysis of 22 parameters allowed the elucidation of a clear reactivity trend of the oil components during biodegradation: lower molecular weight n-alkanes > phenanthrene > 3-2-methylphenanthrenes > intermediate chain length n-alkanes > longer chain length n-alkanes > isoprenoids approximately 9-1-methylphenanthrenes. Irrespective of the individual degrading capacities, all fungi species tested seem to follow this decomposition sequence.

Trace metals in suspended particles, sediments and Asiatic clams (Corbicula fluminea) of the Río de la Plata Estuary, Argentina.

Suspended particulate matter (SPM), sandy sediments and Asiatic clams were collected at seven sites along 150 km of the Río de la Plata coast to assess the magnitude of trace metal pollution in the area. Metal concentrations in SPM (Cu: 7.4-109; Cr: 75-408; Mn: 525-1341 microg(-1)), sediments (Cr: 16-27; Zn: 26-99; Mn: 221-489 microg(-1)) and bivalves (Cd: 0.5-1.9; Ni: 1.3-6.4; Cr: 1.3-11; Mn: 15-81; Cu: 28-89; Zn: 118-316 microg g(-1)) are comparable to those reported for other moderately polluted world rivers. Cu levels in Asiatic clams are among the highest, similar to those reported for heavily polluted sites. SPM Cu and Cr concentrations displayed a clear geographical trend with values increasing with proximity to major urban centers. Sediments showed a less clear pattern possibly due to their coarse nature (>98% sand) and higher proportion of mineral-associated residual metals. The clams showed a complex pattern due to the variability introduced by size-related factors and the natural dynamics of SPM in the estuary. Cr and Mn showed an apparent reverse industrial trend with higher concentrations in clams collected at distant stations near the turbidity maximum zone, possibly reflecting enhanced particle retention. Cu, Cd and Ni showed no clear geographical pattern, whereas Zn increased in the clams collected in the most industrialized area. A significant relationship with clam size was observed for Cu (positive) and Zn (negative) suggesting different physiological requirements for both metals with age. A principal component analysis confirmed these geographical and size-related trends.

Environmental toxicity assessment in the Paraná river delta (Argentina): simultaneous evaluation of selected pollutants and mortality rates of Corbicula fluminea (Bivalvia) early juveniles.

Water and sediment samples were collected in the lower Paraná delta at four sites with different levels of exposure to pollution to evaluate the anthropogenic impact through chemical analyses and mortality bioassays. Individual polychlorinated biphenyls, chlorinated pesticides, aliphatic hydrocarbons, polycyclic aromatic hydrocarbons, and heavy metals were measured in waters, porewaters and sediments. The same three phases were also subjected to toxicity assays with straight-hinged juveniles of Corbicula fluminea. Concentrations of several pollutants were above levels recommended for the protection of aquatic life: in waters, Zn, Cu and Cr were 1.6-4.9 times higher, whereas in the sediments Cr was 1.8-3.6, and benzo(a)pyrene was 2.8-5.6 times higher. Pollutant concentrations followed a clear geographic pattern with highest values in the densely populated area of the Reconquista and Luján rivers, lower levels in the San Antonio, and lowest loadings in the remote Paraná de las Palmas. This gradient was adequately matched by the pattern of mortality rates of C. fluminea early juveniles, which were highest in the Reconquista-Luján (40-93%) and lowest (and not significantly different from the control) in the Paraná (3.3-23%). Mortality rates also increased from surface waters (3.3-53%), to porewaters (12-73%), to sediments (23-93%). Although toxicity was probably mainly due to dissolved contaminants, agreement between chemical and biological evidence of pollution was best for the sediment compartment, whereas porewater and surface water showed a higher degree of variability.

Sources, distribution and variability of airborne trace metals in La Plata City area, Argentina.

Airborne particulate trace metals have been measured bimonthly during day and night hours in four permanent stations located in residential, industrial and commercial sectors of La Plata City region, to characterize the sources and variability of atmospheric inputs. Airborne trace metal regional averages (Pb 64 +/- 62, Cu 30 +/- 27, Mn 26 +/- 20, Zn 273 +/- 227, Fe 1183 +/- 838, Ca 5343 +/- 3614, Mg 1472 +/- 967, Cr 4.3 +/- 2.4, Ni 3.2 +/- 3.5 and Cd 0.41 +/- 0.42 ng/m3) are comparable to the values reported for not grossly polluted cities and below the general trend described for urban particulates. Two- and three-way analysis of variance and variance components tests (P < 0.05) were performed to assess the contribution of the diurnal (day vs. night), spatial (inter-station) and temporal (inter-month) components of variability. Trace metal concentrations followed the behavior of total suspended particles with higher concentrations during the day and at the Downtown station and lower at the Residential site. In general, spatial and temporal variations prevailed over diurnal differences. Spatial differences were clearly most significant for Pb, which presented higher values at the Downtown site reflecting the importance of motor exhaust inputs. In contrast, diurnal differences were more important for Mn due to increased dust resuspension during day hours. A seasonal trend with concentrations usually increasing during winter months and decreasing in spring-summer was also detected. Enrichment factors (EF) were calculated to evaluate anthropogenic versus natural element sources. High EF (21-376) were obtained for Pb, Zn, Cd and Cu reflecting the importance of anthropic inputs. The comparison with EF calculated for high-emitting vehicle particle emissions indicated that motor exhausts are the most important source of these elements in La Plata region. In contrast, the EF calculated for Mn, Cr, Ni, Ca and Mg were low (1.3-7.5) suggesting chiefly natural sources, i.e. soil-derived dusts.