J.C. Colombo

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.

Trace metals in suspended particles, sediments and Asiatic clams (Corbicula fluminea) of the Rio 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.

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.

Lipid biogeochemistry in the Laurentian Trough: I—fatty acids, sterols and aliphatic hydrocarbons in rapidly settling particles

Sinking particles intercepted at 150 m depth in May and July at landward (L) and seaward (S) sites in the Laurentian Trough contained 540–2910 μg g−1 of fatty acids (FA), 54–990 μg g−1 of sterols and 101–184 μg g−1 of aliphatic hydrocarbons. The vertical fluxes averaged 7.2, 3.1 and 0.8 mg m−2 d−1, respectively. FA fluxes (greater at site L) and concentrations (higher at S and during July) reflected the terrestrial-marine gradient and the seasonal patterns of primary production in the estuary. Unresolved anthropogenic hydrocarbons (UCM) displayed an opposite trend. The sources and behaviour of individual lipid biomarkers were evaluated by multivariate techniques. FA 16:0 and 16:1, heneicosahexaene and 24-methylcholest-5-en-3β-ol were the most consistent tracers of an early diatom bloom sampled at the seaward site. FA 14:0 and 15:0, squalene and 24-methylcholesta-5,22E-dien-3β-ol also traced this event but were less specific. The summer increase of primary production was reflected by cholestanol, 24-methylenecholesterol, 24-norcholesta-5,22E-dien-3β-ol, 24-ethylcholesta-5,22E-dien-3β-ol and dinosterol. Zooplanktonic pristane, unsaturated FA, cholesterol and cholesta-5,22E-dien-3β-ol, were abundant in all the traps. At the landward site, cholesterol and cholesta-5,22E-dien-3β-ol covaried with dinosterol, suggesting a dinoflagellate contribution as well. These samples were very heterogeneous and showed variable inputs from higher plants (stigmastanol, FA 24:0, 26:0, long-chain n-alkanes), petrogenic hydrocarbons (n-alkanes, UCM) and plankton (unsaturated FA, cholesterol), reflecting the combined contribution from the Upper St. Lawrence Estuary, Saguenay Fjord and a periodic upwelling.

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.

Bioaccumulation of Polychlorinated Biphenyls and Chlorinated Pesticides by the Asiatic Clam Corbicula fluminea; Its Use as Sentinel Organism in the Rio de La Plata Estuary, Argentina

Individual PCBs and chlorinated pesticides (CHLPs) were determined in water, suspended particles (SPM), sediments, and Asiatic clams to study their bioaccumulation kinetics and evaluate the usefulness of the clams as sentinel organisms. Bioaccumulation depended on the routes of uptake and bioavailability determined by compound hydrophobicity. CHLPs were mainly present in the dissolved phase, showed a positive correlation between the bivalve-water BAFs and K ow s and reached steady-state levels before 70 days in a caging experience. These facts reflect an efficient water-gill partitioning process. In contrast, PCBs were only detected in the SPM, showed essentially K ow independent bivalve-sediment and bivalve-SPM BAFs with the lowest values for super-hydrophobic heptachlorobiphenyls 174, 180, and 170, and did not reach steady-state levels during a 140-day exposure period. This suggests that the uptake was hindered by their stronger affinity for SPM and the interference of steric factors during intestine absorption. Corbicula fluminea are reliable sentinel organisms and showed clear geographical trends along 150 km of the Rio de La Plata coast : a progressive decrease of PCB levels and more degraded patterns dominated by recalcitrant congeners, i.e., 153, were observed with increasing distance from the major La Plata-Buenos Aires urban center. A size-related trend overlapped with this spatial gradient : older clams usually showed higher levels and a more degraded PCB signature. CHLPs showed less clear geographical trends due to the presence of multiple sources. CHLP patterns showed a strong dominance of chlordane-related compounds, particularly trans-chlordane which was 2-5 times more abundant than the cis isomer. On a temporal scale, from 1986 to 1993, Asiatic clams presented sustained PCB levels but showed a significant decrease of chlordane and DDT, which suggests reduced inputs in recent years.

Lipid biogeochemistry in the Laurentian Trough—II. Changes in composition of fatty acids, sterols and aliphatic hydrocarbons during early diagenesis

Abstract Interfacial sediments of the 300-m deep Laurentian Trough contained 3.2–11, 1.2–6.2, 0.4–2.4, 0.2–0.5 mg g −1 OC of fatty acids, unresolved hydrocarbons (UCM), sterols, and resolved aliphatic hydrocarbons, respectively, reflecting a 46–93% loss relative to settling particles intercepted at 150 m depth. A further 22–66% lipid loss was observed between 0–3 and 35 cm depth in the sediments. Lipid accumulation efficiencies in the top 3 cm sediment inventory averaged 21 ± 29% of water column fluxes, and indicated a clear reactivity trend: pheopigments > sterols > fatty acids ≈ total lipids > resolved hydrocarbons > UCM. However, within each lipid class, marine-derived components were as highly reactive as pheopigments, whereas terrestrial compounds behaved akin to the UCM. Extremely labile marine lipids that were enriched in settling particles, such as pristane, 24-methylcholesta-5, 22E-dien-3β-ol, and heneicosahexaene, were quickly lost near the sediment-water interface. Only moderately reactive components (16:0, 16:1 fatty acids, squalene) and the more stable 22:0 and 24:0 acids, fichtelite and UCM persisted deep enough to preserve the geographical trends observed for rapidly settling particles, i.e. predominance of terrestrial and petrogenic compounds at a landward site and prevalence of marine lipids at a station located 120 km further seaward. The preferential decay of marine components continued with depth in the cores, resulting in similar residual lipid patterns at 35 cm depth. However, each site could still be discriminated clearly by its fatty acid and hydrocarbon composition. In situ sedimentary processes, such as the vertical distribution of bacteria and the production of coprostanol, were also recorded in the lipid composition of these deep coastal sediments.

Persistent Organic Pollutants (POPs) in Eastern and Western South American Countries

Persistent organic pollutants (POPs) are a global issue. The recently signed Stockholm POP convention requires information from signatory countries regarding sources and environmental levels. In eastern and western South American countries, this information is not always easily accessible, and therefore an effort toward collection of updated information is required. This review attempts to fulfill these requirements by analyzing the existing information regarding environmental levels of POPs in eight countries of South America.

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.

Sources, distribution and variability of airborne particles and hydrocarbons in La Plata area, Argentina

Abstract Total suspended particles (TSP), particulate- (ALIp) and semi-volatile aliphatic hydrocarbons (ALIsv) were measured in air sampled during the day and night over 7–8 months in industrial, commercial and residential sectors of La Plata, Argentina. TSP, ALIp and ALIsv ranges were 23–219 μg/m3, 11–447 and 12–719 ng/m3, respectively. Maximum values were recorded at a downtown site whereas the residential station showed lower levels. Concentrations were usually higher during the day and during fall and winter. Two- and three-way ANOVA were performed to evaluate the day-night, inter-station, and inter-month variability. The amount of total variability accounted by these factors was 14, 25 and 23% (p