A comparison of two techniques for studying sediment desorption kinetics of hydrophobic pollutants

A comparison of two techniques (gaseous purge and vial desorption) for studying the kinetics of desorption of hydrophobic pollutants from natural sediments was conducted using identical, pre-equilibrated pollutant-sediment suspensions. Desorption profiles for the two techniques [for Lindane, Aldrin, 2,2'-dichlorobiphenyl (2,2'-DCB), 4,4'-dichlorobiphenyl (4,4'-DCB), and 2,2',6,6'-tetrachlorobiphenyl (TCB)] were then compared, based on the distribution of pollutant mass between the labile (fast) and non-labile (slow) desorption phases and the release rate constants for each phase of release. The vial desorption technique shows many practical advantages over the gaseous purge technique, including its more realistic mixing conditions, the use of an independent sample for each data point (as opposed to a calculation of a cumulative mass purged at each time point), the fact that the vials constitute a closed system and are therefore less subject to ambient contamination, and the relatively low demands of time and money for the vial technique. No consistent trends in labile rate constants or in pollutant distribution between the labile and non-labile phase were observed between the two techniques. A comparison of kinetic parameters shows much faster non-labile rate constants for the gaseous purge technique, attributed to the violent, continuous agitation employed, which likely disrupted sediment aggregates and oxidized the natural organic matter associated with the sediment. Non-labile rate constants have implications for the long-term fate of compounds adsorbed to repetitively disturbed sediments. This study suggests that the traditionally less popular vial desorption technique may yield more realistic non-labile desorption rate constants.     

Bioremediation of kerosene I: A case study in liquid media

The ability of different local isolates in addition to some isolates from Germany to degrade kerosene in liquid medium was studied. The results showed that the percent of kerosene degradation varied among the different organisms and that 59–94% of kerosene was degraded after 21 d. Two local isolates (Pseudomonas sp. AP and Pseudomonas sp. CK) and one German isolate (Gordonia sp. DM) were selected for this study. The addition of wheat bran, as co-substrate, stimulated the kerosene degradation by the two local strains, while glucose inhibited the degradation rate using the three organisms with different rates. Ammonium nitrate and urea was the best nitrogen sources. The use of superphosphate (as phosphorus source) in the presence of urea stimulates the degradation rate. It was also observed that the addition of 1% surfactants, like Triton X-100, Igepal, Tergitol, or Tween 20 and 80 enhanced the kerosene degradation. The degradation percent lied between 94% and 98%. The ability of the tested organisms to degrade kerosene concentration from 2% to 8% was evaluated. It was found that the three organisms degraded about 65–85% from 8% kerosene after 21 d. The use of rice straw-immobilized cells reduced the time of degradation and enhanced the degradation ability of the organisms. The sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed the presence of a common protein band when the tested organisms were grown on kerosene.     

Seasonal variations of selected herbicides and related metabolites in water, sediment, seaweed and clams in the Sacca di Goro coastal lagoon (Northern Adriatic)

This study assesses the status of Sacca di Goro coastal lagoon (Northern Adriatic, Italy) with respect to watershed pollution. Because 80% of its watershed is devoted to agriculture, plant protection products and their metabolites were found in the water column, sediments (the upper 0-15 cm layer), macroalgae (Ulva rigida) and clams (Tapes philippinarum). Five seasonal sampling campaigns were performed from May 2004 to April 2005 and concentrations measured in five stations in the lagoon and six in the watershed. Relatively high concentrations of the s-triazine - terbuthylazine -, urea herbicides - diuron - and alachlor were detected through the year mainly at stations directly influenced by the Po di Volano inflow. The concentrations of products in use follow a clear seasonal pattern with spring peaks. This pattern is also visible in the sediments as well as in biota. Among metabolites, hydroxylated compounds prevailed, often with concentrations greater than those of the parent compounds. For the most part of the year, the concentrations in biota were close to detection limits, with concentration peaks in spring.     

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.     

Estrogenic activity removal of 17beta-estradiol by ozonation and identification of by-products

This work investigated the degradation of a natural estrogen (17beta-estradiol) and the removal of estrogenic activity by the ozonation process in three different pHs (3, 7 and 11). A recombinant yeast assay (YES assay) was employed to determine estrogenic activity of the ozonized samples and of the by-products formed during the ozonation. Ozonation was very efficient for the removal of 17beta-estradiol in aqueous solutions. High removals (>99%) were achieved with low ozone dosages in the three different pHs. Several by-products were formed during the ozonation of 17beta-estradiol. However, only a few compounds could be identified and confirmed. Different by-products are formed at different pHs, which is probably due to different chemical pathways and different oxidants (O(3) and OH radical). The by-products formed at pH 11 were 10epsilon-17beta-dihydroxy-1, 4-estradieno-3-one (DEO) and 2-hydroxyestradiol, which were not formed in pH 3. Only testosterone could be observed in pH 3, whereas at pH 7 all three by-products were found. At pH 7 and 11 the applied ozone dosages were not enough to remove all the estrogenicity from samples, even though the 17beta-estradiol residual concentration for these two pHs was lower than at pH 3. Higher estrogenicity was detected at pH 11. An explanation to this fact may be that oxidation via OH radical forms more by-products with estrogenic activity. Probably, the formation of 2-hydroxyestradiol at pHs 7 and 11 is contributing to the residual estrogenicity of samples ozonized at these pHs. In this work, complete removal of estrogenic activity was only obtained at pH 3.     

Bioremediation process on Brazil shoreline

GOAL, SCOPE AND BACKGROUND: Bioremediation technique can be considered a promising alternative to clean oil spills using microbial processes to reduce the concentration and/or the toxicity of pollutants. To understand the importance of this work we must know that there is only little research performed to date using bioremediation techniques to clean oil spills in tropical countries. So, the main objective of this work is to analyze the behavior of a laboratory's bioremediation test using nutrients on coastal sediments. METHODS: The bioremediation process is followed through geochemical analysis during the tests. This organic material is analyzed by medium pressure liquid chromatography (MPLC), gas chromatography/flame ionization detection (GC/FID) and gas chromatography/ mass spectrometry. By microbial counting, the number of total bacteria and degrading bacteria is determined during the experiments, in order to confirm the effectiveness of the bioremediation process. The seawater obtained throughout the bioremediation process is analyzed for nutrients grade (phosphate and ammonium ions) and also for its toxicity (Microtox tests) due the presence of hydrocarbons and fertilizer. RESULTS: The results from the geochemical analyses of the oil show a relative decrease in the saturated hydrocarbon fraction that is compensated by a relative enrichment on polar compounds. It's confirmed by the fingerprint evaluation where it is possible to see a complete reduction of the normal alkanes followed by isoprenoids. Seawater analysis done by toxicity and nutrients analysis, such as microbial counting (total and degrading bacteria), confirm the fertilizer effectiveness during the bioremediation process. DISCUSSION: Results from simulating test using NPK, a low-price plant fertilizer, suggest that it's able to stimulate the degradation process. Results from medium pressure liquid chromatography (MPLC), done at two different depths (surface and subsurface), show different behavior during the biodegradation process where the later is seen to be more susceptible to microbial attack. Data from bioremediation unit shows a bigger reduction of the saturated fraction, followed by some smaller reduction of aromatic fractions, compensated by a relative increase from polar compounds (NSO). n-C17/pristane, n-C18/ fitane and pristane/fitane rates show constant values for the unity control, different from bioremediation samples which have a significant reduction, especially on subsurface areas, where a strong fall in the rates, seen to be reduced to zero over twenty days, had occurred during the first ten days. However, sample surfaces are reduced to zero in thirty days of experiments, proving that biodegradation is better on subsurfaces. Gaseous chromatography/mass spectrometry (CG/MS) analysis shows constant values to cyclic biomarker rates and aromatic compounds, suggesting that the biodegradation process is not strong enough to reduce these composites. Microbial analysis shows a reduction on heterotrophic (total bacteria) number from control unit, probably because the bacteria uses the spill oil like carbon source and energy. However, the number increases on bioremediation unit, because it uses NPK like a biostimulator. The hydrocarbonoclastic number isn't enough on the first moment, but it's detected after 30 days and quantified in all units, showing big values especially in bioremediation. Toxicity tests confirm that NPK fertilizer does not intoxicate the shoreline during the application of the bioremediation technique. Some nutrient concentration shows high values of ammonium and phosphate per bioremediation unit, reducing by the end of the experiment. CONCLUSIONS: Results reached the goal, finding a proper nutrient (NPK fertilizer) to stimulate the biodegradation process, growing bacteria responsible for reducing impact-contaminated coast ambient by oil spills. Chemical analysis of oil shows a reduction in the saturated fraction with a relative enrichment in polar composites (NSO) and the aromatic fraction from oil remaining constant. Subsurface samples show more biodegradation than surface samples, probably because the first one has higher humidity. Linear alcanes are more biodegraded than isoprenoids, confirming the biodegradation susceptibility order. Saturated cyclic biomarkers and aromatic compounds show constant behavior maybe because the nutrients or time was not enough for microorganismic attack. Fertilizer does not demonstrate any toxic effects in local biota so that it does not compromise the technique applicability and the environment is not saturated by nutrients during the simulation, especially since the coastal environment is an open system affected daily by tides. Therefore, bioremediation tests can be classified as moderate, reaching level 5 in the classification scale by Peters & Moldowan (1993). RECOMMENDATIONS AND PERSPECTIVES: The use of marine environment by the petroleum industry on exploration, production and transportation operation, transform this oil to become the most important pollutant in the oceans. Bioremediation is an important technique used to clean spilled oil impacting on shorelines, accelerating the biodegradation process by using fertilizer growing the microorganisms responsible for decontaminating the environment. We recommend confirming the efficiency of NPK nutrient used on bioremediation simulating experiments on beaches, while monitoring the chemical changes long-term. NPK fertilizer can be used to stimulate the biodegradation process on shoreline impacted by spilled oil.     

Deficit analysis: service capacity assessment and planning in developing countries – case study in the Philippines

Current demand analysis methods do not formally cover the case of chronic deficits in quantity or quality of water and sanitation services. These services include drinking water supply (DWS), wastewater and sewage treatment (WST), and municipal solid waste management (MSW). Formal analysis of this case would, at minimum, define the deficit state and evaluate appropriate options for reducing it. This paper proposes for a formal analytical model for municipal sanitation systems (MSS) that operate with deficits in at least one of the constituent services of DWS, WST, or MSW. The model introduces definitions and notation for describing the deficit state for conducting demand analysis on municipal sanitation systems. This model of demand analysis for systems with chronic deficits will hereinafter be referred to as deficit analysis. A case study for Bacoor, Philippines is presented as an example.