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 μg g⁻¹, dry, fresh and lipid weight, respectively) and UCM (931 ± 560, 399 ± 288 and 1567 ± 802 μg 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 (1750 vs. 1083 ± 4.6 mm 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 25.4 Å) with melting points ranging from −19.8 to 28 °C. The uptake efficiency is inversely correlated to melting points and increased from 75% for n-C₂₅ to above 90% for n-C_14–15 and isoprenoids.     

Reevaluation of ENCORE: support for the eutrophication threshold model for coral reefs

The results from the multimillion dollar Enrichment of Nutrients on Coral Reefs Experiment (ENCORE) on One Tree Island Reef (OTIR) suggest that increased nutrient loads to coral reefs will have little or no effect on the algal growth rates and, hence, on the associated effects that increased algal growth might have on the functioning and stability of coral reefs. However, a comparison of the concentrations of nutrients within the OTIR lagoon with the proposed nutrient threshold concentrations (NTC) for coral reefs suggests that all sites, including the control sites, were saturated with nutrients during ENCORE, and, hence, one would not expect to get any differences between treatments in the algal-growth related measurements. Thus, ENCORE results provide strong support for the proposed NTCs and support the ecological principle that algal productivity and, consequently, the functioning of coral reefs are sensitive to small changes in the background concentrations of nutrients. The principal conclusion of ENCORE, namely that the addition of nutrients did not cause the "pristine" OTIR to convert from coral communities to algal dominated reefs, is contrary to the fact that there was prolific macroalgal growth on the walls and crests of the experimental microatolls by the end of ENCORE.     

Integrated biomonitoring of air quality with plants and lichens: a case study on ambient ozone from central Italy

A biennial integrated survey, based on the use of vascular plants for the bioindication of the effects of tropospheric ozone together with the use of automatic analysers of ozone, as well as the mapping of lichen biodiversity was performed in the area of Castelfiorentino (Tuscany, central Italy). Photochemically produced ozone proved to be a fundamental presence during the warm season, with maximum hourly means reaching 114 ppb, exceeding the information threshold as fixed by EU: the use of supersensitive tobacco Bel-W3 confirmed the opportunity of carrying out detailed cost-effective monitoring surveys. The potential for didactical and educational implications of this methodology are appealing. Critical levels set up for the protection of vegetation have exceeded considerably. The comparison of biomass productivity in sensitive and resistant individuals (NC-S and NC-R white clover clones, in the framework of an European network) provided evidence that ambient ozone levels are associated with relevant reduction (up to 30%) in the performance of sensitive material; effects on flowering were also pronounced. The economic assessment of such an impact deserves attention. Mapping of epiphytic lichen biodiversity – which has been used to monitor air quality worldwide – was not related to ozone geographical distribution as depicted by tobacco response.     

Assessment of pesticide contamination in three Mississippi Delta oxbow lakes using Hyalella azteca

Three oxbow lakes in northwestern Mississippi, USA, an area of intensive agriculture, were assessed for biological impairment from historic and current-use pesticide contamination using the amphipod, Hyalella azteca. Surface water and sediment samples from three sites in each lake were collected from Deep Hollow, Beasley, and Thighman Lakes from September 2000 to February 2001. Samples were analyzed for 17 historic and current-use pesticides and selected metabolites. Ten-day H. azteca survival and growth (as length and dry weight) were measured to determine the degree of biological impairment. Maximum number of detectable pesticides in surface water from Deep Hollow, Beasley and Thighman Lakes was 10, 11, and 17, respectively. Maximum number of detectable pesticides in lake sediments was 17, 17, and 15, respectively. Bioassay results indicated no observable survival effects on H. azteca exposed to surface water or sediment from any lake examined and no growth impairment in animals exposed to lake sediments. However, growth was significantly impaired in surface water exposures from Deep Hollow Lake (2 sites) and Beasley Lake (1 site). Statistically significant relationships between growth impairment (length) and cyanazine, methyl parathion, λ-cyhalothrin, chlorfenapyr, and pp′DDE surface water concentrations in Deep Hollow Lake as well as trifluralin, atrazine, and methyl parathion in Beasley Lake were observed. Although pesticide frequency and concentrations were typically greater in sediment than surface water, bioassay results indicated decreased availability of these pesticides in sediment due to the presence of clay and organic carbon. Growth impairment observed in surface water exposures was likely due to complex interaction of pesticide mixtures that were present.     

Cellular evaluation of the toxicity of combustion derived particulate matter: influence of particle grinding and washing on cellular response

There is increasing interest in continual monitoring of air for the presence of inhalation health hazards, such as particulate matter, produced through combustion of fossil fuels. Currently there are no means to rapidly evaluate the relative toxicity of materials or to reliably predict potential health impact due to the complexity of the composition, size, and physical properties of particulate matter. This research evaluates the feasibility of utilizing cell cultures as the biological recognition element of an inhalation health monitoring system. The response of rat lung type II epithelial (RLE-6TN) cells to a variety of combustion derived particulates and their components has been evaluated. The focus of the current work is an evaluation of how particles are delivered to a cellular sensing array and to what degree does washing or grinding of the particles impacts the cellular response. There were significant differences in the response of these lung cells to PM's of varying sources. Mechanical grinding or washing was found to alter the toxicity of some of these particulates; however these effects were strongly dependent on the fuel source. Washing reduced toxicity of oil PM's, but had little effect on those from diesel or coal. Mechanical grinding could significantly increase the toxicity of coal PM's, but not for oil or diesel.     

Adsorption of natural organic matter from waters by iron coated pumice

Natural pumice particles were used as granular support media and coated with iron oxides to investigate their adsorptive natural organic matter (NOM) removal from waters. The impacts of natural pumice source, particle size fraction, pumice dose, pumice surface chemistry and specific surface area, and NOM source on the ultimate extent and rate of NOM removal were studied. All adsorption isotherm experiments were conducted employing the variable-dose completely mixed batch reactor bottle-point method. Iron oxide coating overwhelmed the surface electrical properties of the underlying pumice particles. Surface areas as high as 20.6m(2)g(-1) were achieved after iron coating of pumice samples, which are above than those of iron coated sand samples reported in the literature. For all particle size fractions, iron coating of natural pumices significantly increased their NOM uptakes both on an adsorbent mass- and surface area-basis. The smallest size fractions (<63 microm) of coated pumices generally exhibited the highest NOM uptakes. A strong linear correlation between the iron contents of coated pumices and their Freundlich affinity parameters (K(F)) indicated that the enhanced NOM uptake is due to iron oxides bound on pumice surfaces. Iron oxide coated pumice surfaces preferentially removed high UV-absorbing fractions of NOM, with UV absorbance reductions up to 90%. Control experiments indicated that iron oxide species bound on pumice surfaces are stable, and potential iron release to the solution is not a concern at pH values of typical natural waters. Based on high NOM adsorption capacities, iron oxide coated pumice may be a promising novel adsorbent in removing NOM from waters. Furthermore, due to preferential removal of high UV-absorbing NOM fractions, iron oxide coated pumice may also be effective in controlling the formation of disinfection by-products in drinking water treatment.     

Pteris umbrosa R. Br. as an arsenic hyperaccumulator: accumulation, partitioning and comparison with the established As hyperaccumulator Pteris vittata

The capacity of the Australian native fern Pteris umbrosa to function as an arsenic (As) hyperaccumulator (shoot:soil As concentration >1) was examined by growing plants under glasshouse conditions in an inert medium supplemented with As. Arsenic preferentially accumulated in the fronds, a trait of a hyperaccumulator. The As concentration of fronds decreased with age, being particularly high in the croziers and low in the senesced fronds. Below ground, rhizomes accumulated more As than adventitious roots. Uptake from a range of solution concentrations followed Michaelis Menten kinetics up to a soil solution As concentration of 400mgl(-1). The K(m) for As uptake by roots suggested the operation of a low-affinity carrier. The predicted Nernst membrane potential indicated that uptake was against the electrochemical gradient of As. At 600mgl(-1), the rate of As uptake increased and phytotoxic effects were indicated by a significant decline in biomass. Arsenic uptake and translocation in P. umbrosa and Pteris vittata were similar at low exposure to As. At higher exposure, As uptake and translocation by P. vittata increased more than in P. umbrosa. The growth rate of both ferns was similar, whereas the biomass distribution was not, with P. vittata having a much larger root mass. This suggests that As uptake by P. umbrosa roots was very efficient and may be improved by stimulating root growth to enhance its potential.     

Cellular alterations in different organs of European sea bass Dicentrarchus labrax (L.) exposed to cadmium

Specimens of farmed European sea bass (Dicentrarchus labrax L., 1758) were exposed to different cadmium (Cd) concentrations (4.47, 5.63, 7.08 and 8.91 mg l(-1)) for 24 and 48 h. The effects of Cd on numbers of some cell types and structures (i.e., chloride cells, CCs; macrophage aggregates, MAs; rodlet cells, RCs) and on structure and ultrastructure of the main organs (gill, liver, intestine, kidney) were studied with routine process for light and transmission electron microscopy. Following cadmium exposure, the numbers of branchial CCs as well as intestinal and renal RCs increased significantly within 24h. Increase in metal concentration did not affect the magnitude of the numerical increment of the aforementioned cells. Moreover, in treated fish (24 and 48 h) the numbers of MAs in both head kidney and spleen were significantly higher than in control conspecifics, whilst the global area of MAs was less influenced by the acute treatment. In exposed sea bass, all the examined organs exhibited cellular modifications which appeared time- and dose-dependent. The gills showed telangectasia, lamellar fusion, oedema, epithelial lifting and leukocyte infiltration. In the liver, kidney and intestine acute cell swelling and vacuolization were common. Ultrastructurally the alterations observed frequently in hepatocytes, tubular epithelial cells and enterocytes included presence of numerous myelinoid bodies, damaged mitochondria, dilatation of endoplasmic reticulum, high number of lysosomes and autophagolysosomes. In intestinal and kidney tubular epithelia of treated fish, rodlet cells displayed some anomalies like dilatation of nuclear envelope, cytoplasmic vacuolization, presence of myelinoid bodies, rodlets degeneration and extensive discharge activity.     

The historical record of PCB and PCDD/F deposition at Greifensee, a lake of the Swiss plateau, between 1848 and 1999

Dated sediment cores provide an excellent way to investigate the historical input of persistent organic pollutants into the environment and to identify possible sources of pollution. The vertical distribution of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/F) and polychlorinated biphenyls (PCB) was investigated in a sediment core from Greifensee to elucidate the historical trends of PCDD/F and PCB inputs between 1848 and 1999. Concentrations of PCB and PCDD/F increased by more than one order of magnitude between 1930 and 1960. PCB and PCDD/F concentrations were 5700 ng/kg dry weight (dw) and 160 ng/kg dw, respectively, in sediments originating from the late 1930s and reached a maximum of 130,000 ng/kg dw and 2400 ng/kg dw, respectively, in the early 1960s. From 1960 on, concentrations decreased to the 1930s level by the mid 1980s. A remarkable shift in the PCDD/F pattern was observed after the early 1940s. Before 1940, the PCDD/F pattern was PCDF dominated (ratio of PCDD to PCDF=0.41+/-0.11), while the PCDD started to be the major species after the early 1940s (ratio of PCDD to PCDF=1.46+/-0.38). The temporal trends of PCB and PCDD/F correlate surprisingly well with each other. This might be due to the coincidence of two factors. The introduction of PCB on the market in the 1930s resulted in emissions due to the widespread use of these industrial chemicals. In the same time period, waste incineration became an increasingly popular way to get rid of garbage, boosting the PCDD/F emissions significantly. The rapid decline of PCDD/F and PCB concentrations in the sediment starting in the early 1960s reflects the result of better emission control techniques in thermal processes and the improvement of waste water treatment in the catchment of Greifensee.