Phytoplankton and water quality characterization: experiences from the Swedish large lakes Mälaren, Hjälmaren, Vättern and Vänern

Phytoplankton and environmental variables have been monitored in the large Swedish lakes M?laren, Hj?lmaren, V?ttern and V?nern since the 1960s. Measures to reduce phosphorus input and industrial waste products were taken during the 1970s. The phosphorus loading was then reduced by 90-95% resulting in a halving of the phosphorus concentrations in the most affected basins. The phytoplankton community reacted rapidly with decreased biomasses of cyanobacteria in summer as well as decreased biomasses of spring diatoms and cryptophycean flagellates. Other reactions were a contracted period of water-bloom, an increased taxon richness, an increased evenness in the biomass over the growth season, and a change in the species size structure within the phytoplankton community. Furthermore, the species richness in the large lakes is compared in relation to lake characteristics. A presentation of the occurrence of toxic cyanobacteria in the lakes is also given. Maximum-minimum values of 13-0.1 micrograms microcystin L-1 are established in connection with water-blooms in Hj?lmaren and M?laren. The use of phytoplankton as a monitoring variable to detect water-quality changes is outlined and assessment criteria are presented.     

Cobalt-based alumina pillared zirconium phosphate catalysts for the selective catalytic reduction of NO by propane

A series of cobalt containing alumina pillared zirconium phosphate materials have been prepared by ion exchange or by impregnation, and fully characterised. The catalytic behaviour of these materials in the selective catalytic reduction of NO by propane, in excess of oxygen, at temperatures ranging between 350 and 550 degrees C, has been also evaluated. A maximum NO conversion close to 14% is obtained on Co-impregnated catalysts heated at 600 degrees C. The NO reduction seems to be related to the presence of Co3+, thus the calcination temperature of samples influences the resulting activity much more than the cobalt content.     

A model for estimating the potential biomagnification of chemicals in a generic food web: Preliminary development

GOAL, SCOPE AND BACKGROUND: Bioaccumulation and biomagnification of organic pollutants have been increasingly assessed and modeled during the last years. Due to the complexity of these processes and the large variability of food webs, setting generic assessments for these parameters is really difficult. Equilibrium models, based on a compound's lipophylicity, are the main tool in regulatory proposals, such as for identifying Persistent, Bioaccumulative and Toxic Substances (PBTs), although a refinement has been claimed by the scientific community. Toxicokinetic studies offer an alternative for these estimations, where biomagnification is modeled as a succession of bioaccumulation processes, each one regulated by toxicokinetic parameters. METHODS: A review of kinetic models covering species belonging to different trophic levels and with different ecological behavior has been conducted. The results were employed for setting a conceptual model for estimating the biomagnification potential in a generic food web, which was mathematically implemented through system dynamic models developed under data sheet software. Crystal Ball was then employed for allowing Monte Carlo based probabilistic calculations. Bioaccumulation laboratory assays have been performed to estimate toxicokinetic parameters in mussels (Mytilus edulis) with two PAHs (chrysene and benzo[a]pyrene). The contamination was delivered via food. The exposure period lasted more than one month followed then by a depuration phase. The contaminant content was determined on an individual basis on five replicates. RESULTS AND DISCUSSION:. The reviewed information suggested the development of a tiered conceptual biomagnification model, starting with a simplified food chain which can be refined to more realistic and complex models in successive levels. CONCLUSIONS: The mathematical implementation of the conceptual model offers tools for estimating the potential for bioaccumulation and biomagnification of chemicals under very different conditions. The versatility of the model can be used for both comparative estimations and for validating the model. RECOMMENDATIONS AND PERSPECTIVES: Since bioaccumulation and biomagnification processes are crucial elements for a proper risk assessment of chemicals, their estimation by mathematical models has been widely tested. However, inregulatory assessments, too simplistic models are still being used quite often. The biomagnification model presented in this study should be amore accurate alternative to these models. In comparison to other previously published biomagnification models, the present one covers the time variation of bioaccumulation using just a few toxicokinetic parameters.     

Fe(III) promoted LAS (linear alkylbenzenesulfonate) removal from waters

The mechanisms of the interactions between Fe(III) aquacomplexes and surfactants were investigated; three alkylbenzenzsulfonates, two surfactants (octylbenzenesulfonate (OBS) and dodecylbenzenesulfonate (DBS)), and a shorter derivative (ethylbenzenesulfonate (EBS)) were studied. The results with OBS show evidence for three different ways in which Fe(III) interferes with the surfactant: the widely described flocculation process, complexation of Fe(OH)2+ (aquacomplexes) by the surfactant, and a redox reaction. The formation of a weak complex is maximum for a ratio of three between the monomeric aquacomplex [FeOH(H2O)5]2+ and OBS. In the presence of oxygen, an intramolecular redox reaction occurs inside the complex. The interaction between commercial DBS and Fe(III) was also investigated. Immediate precipitation occurred, mainly involving derivatives of higher molecular weights that are contained in the DBS samples. The constituents with the shortest alkyl chain were not affected by the presence of Fe(III) as it was also observed with EBS.     

Coupled solar photo-Fenton and biological treatment for the degradation of diuron and linuron herbicides at pilot scale

A coupled solar photo-Fenton (chemical) and biological treatment has been used to remove biorecalcitrant diuron (42 mg l(-1)) and linuron (75 mg l(-1)) herbicides from water at pilot plant scale. The chemical process has been carried out in a 82 l solar pilot plant made up by four compound parabolic collector units, and it was followed by a biological treatment performed in a 40 l sequencing batch reactor. Two Fe(II) doses (2 and 5 mg l(-1)) and sequential additions of H2O2 (20 mg l(-1)) have been used to chemically degrade the initially polluted effluent. Next, biodegradability at different oxidation states has been assessed by means of BOD/COD ratio. A reagent dose of Fe=5 mg l(-1) and H2O2=100 mg l(-1) has been required to obtain a biodegradable effluent after 100 min of irradiation time. Finally, the organic content of the photo-treated solution has been completely assimilated by a biomass consortium in the sequencing batch reactor using a total suspended solids concentration of 0.2 g l(-1) and a hydraulic retention time of 24h. Comparison between the data obtained at pilot plant scale (specially the one corresponding to the chemical step) and previously published data from a similar system performing at laboratory scale, has been carried out.     

Discriminating the pH toxicity to Poecilia reticulata Peters, 1859 in the Dunas Lake (Camaçari, BA, Brazil)

Toxic potential of the pH reduction to fingerlings of Poecilia reticulata, through acute toxicity bioassays, as well as the influence of increased pH on the toxicity were assessed. Acid lake samples (Dunas Lake) were collected during 19 months, and assessed with following treatments: water at local pH (+/-3.0) and samples with modified pH to 3.5, 3.8, 4.0, 4.3, 4.6, 5.0, 5.5, 6.0, and 6.5. Culture water samples with pH reduced to 3.0 were also assessed. Newborn P. reticulata were exposed during 96h, and dead/immobile organisms were counted at various time intervals during exposure (short intervals in the beginning and long towards the end). Mean results of LT(50) and confidence intervals from the Dunas Lake and control water with reduced pH were 1.36 (+/-0.48)h, and 1.03 (+/-0.50)h, respectively, with no statistical difference. Samples with increased pH showed a significant reduction in toxicity, with no toxicity detected at pH 6.0 and higher. Relationship between pH and lethal toxicity for fingerlings of P. reticulata demonstrated that pH exerted a strong effect on the survival of this species at the Dunas Lake, explaining about 80% of the toxicity observed.     

Antioxidant enzyme activities as affected by trivalent and hexavalent chromium species in Fontinalis antipyretica Hedw

The detoxification mechanisms of the aquatic moss, Fontinalis antipyretica Hedw., exposed to Cr was analyzed. In addition, the influence of Cr salts (as Cr nitrate, chloride and potassium bichromate) on these mechanisms has also been studied. The activity of antioxidant enzymes superoxide dismutase (SOD, EC 1.15.1.1.), catalase (EC 1.11.1.6.), ascorbate peroxidase (APX, EC 1.11.1.11.), guaiacol peroxidase (GPX, EC 1.11.1.7.) and glutathione reductase (GR, EC 1.6.4.2.) increased in plants treated with Cr concentrations ranging from 6.25x10(-5) to 6.25mM when given as Cr(NO(3))(3). Antioxidant enzymes responded to the other two salts CrCl(3) and K(2)Cr(2)O(7) only with Cr concentrations higher than 6.25x10(-2)mM. Glutathione level and GSSG/GSH ratio also responded to Cr exposure but no dose-effect relationship could be observed. Moreover, two unknown thiol compounds were observed in mosses exposed to the highest Cr concentrations. Effects on chlorophyll contents and chlorophyll a/b ratios were also shown even at low Cr concentrations. Our results indicated that environmentally realistic concentrations of Cr could lead to impairment of the cellular activity towards F. antipyretica and that Cr(III), when present as a nitrate salt, was as harmful as Cr(VI).     

Polycyclic aromatic hydrocarbons, black carbon, and molecular markers in soils of Switzerland

Polycyclic aromatic hydrocarbons (PAH) were analysed in 23 soil samples (0–10 cm layer) from the Swiss soil monitoring network (NABO) together with total organic carbon (TOC) and black carbon (BC) concentration, as well as some PAH source diagnostic ratios and molecular markers. The concentrations of the sum of 16 EPA priority PAHs ranged from 50 to 619 μg/kg dw. Concentrations increased from arable, permanent and pasture grassland, forest, to urban soils and were 21–89% lower than median numbers reported in the literature for similar Swiss and European soils. NABO soils contained BC in concentrations from 0.4 to 1.8 mg/g dw, except for two sites with markedly higher levels. These numbers corresponded to 1–6% of TOC and were comparable to the limited published BC data in soil and sediments obtained with comparable analytical methods. The various PAH ratios and molecular markers pointed to a domination of pyrogenically formed PAHs in Swiss soils. In concert, the gathered data suggest the following major findings: (1) gas phase PAHs (naphthalene to fluorene) were long-range transported, cold-condensated at higher altitudes, and approaching equilibrium with soil organic matter (OM); (2) (partially) particle-bound PAHs (phenanthrene to benzo[ghi]perylene) were mostly deposited regionally in urban areas, and not equilibrated with soil OM; (3) Diesel combustion appeared to be a major emission source of PAH and BC in urban areas; and (4) wood combustion might have contributed significantly to PAH burdens in some soils of remote/alpine (forest) sites.     

Genotoxicity detected in wild mice living in a highly polluted wetland area in south western Spain

A field study was carried out in the south of the Iberian Peninsula in an industrial area in the neighbourhood of Huelva city, SW Spain, and in a natural area (Do?ana National Park) for comparison, to estimate the genetic risk induced by environmental pollution in wild mice. Genotoxic effects in a sentinel organism, the Algerian mice (Mus spretus) free living in the industrial area were compared with animals of the same species living in the natural protected area. The single cell gel electrophoresis, or Comet assay, was performed as a genotoxicity test in peripheral blood of mice. Our results clearly show that mice free living in the contaminated area bear a high burden of genetic damage as compared with control individuals. The results suggest that the assessing of genotoxicity levels by the Comet assay in wild mice can be used as a valuable test in pollution monitoring and environmental conservation.     

Levels of perfluorochemicals in water samples from Catalonia,Spain: is drinking water a significant contribution to human exposure?

Background, aim, and scope  In recent years, due to a high persistence, biomagnification in food webs, presence in remote regions, and potential toxicity, perfluorochemicals (PFCs) have generated a considerable interest. The present study was aimed to determine the levels of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and other PFCs in drinking water (tap and bottled) and river water samples from Tarragona Province (Catalonia, Spain). Materials and methods  Municipal drinking (tap) water samples were collected from the four most populated towns in the Tarragona Province, whereas samples of bottled waters were purchased from supermarkets. River water samples were collected from the Ebro (two samples), Cortiella, and Francolí Rivers. After pretreatment, PFC analyses were performed by HPLC-MS. Quantification was done using the internal standard method, with recoveries between 68% and 118%. Results  In tap water, PFOS and PFOA levels ranged between 0.39 and 0.87 ng/L (0.78 and 1.74 pmol/L) and between 0.32 and 6.28 ng/L (0.77 and 15.2 pmol/L), respectively. PFHpA, PFHxS, and PFNA were also other detected PFCs. PFC levels were notably lower in bottled water, where PFOS could not be detected in any sample. Moreover, PFHpA, PFHxS, PFOA, PFNA, PFOS, PFOSA, and PFDA could be detected in the river water samples. PFOS and PFOA concentrations were between <0.24 and 5.88 ng/L (<0.48 and 11.8 pmol/L) and between <0.22 and 24.9 ng/L (<0.53 and 60.1 pmol/L), respectively. Discussion  Assuming a human water consumption of 2 L per day, the daily intake of PFOS and PFOA by the population of the area under evaluation was calculated (0.78–1.74 and 12.6 ng, respectively). It was found that drinking water might be a source of exposure to PFCs as important as the dietary intake of these pollutants. Conclusions  The contribution of drinking water (tap and bottled) to the human daily intake of various PFCs has been compared for the first time with data from dietary intake of these PFCs. It was noted that in certain cases, drinking water can be a source of exposure to PFCs as important as the dietary intake of these pollutants although the current concentrations were similar or lower than those reported in the literature for surface water samples from a number of regions and countries. Recommendations and perspectives  Further studies should be carried out in order to increase the knowledge of the role of drinking water in human exposure to PFCs.