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Common Contaminants (common + contaminant)
Selected AbstractsStress synergy between drought and a common environmental contaminant: studies with the collembolan Folsomia candidaGLOBAL CHANGE BIOLOGY, Issue 4 2001Rikke Hřjer Summary The term global change is used predominantly in connection with the global temperature increase and associated changes in weather patterns over the next century. In a broader sense it also covers other anthropogenic impacts on the environment such as habitat fragmentation and pollution. The individual effects of each of these stress types have been extensively studied in the biota. However, organisms will frequently encounter these stress types in combination rather than alone and there is little information available on the effects of stress combinations. Here an examination is made of the interaction between realistic levels of summer drought and a common contaminant of agricultural soil (4-nonylphenol, NP), on a widespread soil invertebrate, the collembolan Folsomia candida. These stress factors were tested individually and in combination using a full factorial design. This approach revealed the existence of highly significant Bliss type synergistic interaction between the two stress types. Thus, exposure to NP significantly reduced the drought tolerance of this organism and, reciprocally, the toxicity of NP (LC50) during realistic summer drought was more than doubled in comparison to the value obtained under optimal soil moisture conditions. Furthermore, it is shown that NP has a detrimental effect on the physiological mechanisms underlying this animal's drought tolerance, thus providing some explanation for the mechanisms involved in the synergy. It is argued that this type of synergy is unlikely to be confined to this particular combination of stresses and thus there is a need to study the interactions between dominant natural stresses and pollution. The most important implication of these results is that some of the effects of global climate changes can be predicted to be most severe in polluted areas. [source] PRODUCTION OF PHYTOCHELATINS AND GLUTATHIONE BY MARINE PHYTOPLANKTON IN RESPONSE TO METAL STRESS,JOURNAL OF PHYCOLOGY, Issue 5 2006Silvia K. Kawakami Phytoplankton deal with metal toxicity using a variety of biochemical strategies. One of the strategies involves glutathione (GSH) and phytochelatins (PCs), which are metal-binding thiol peptides produced by eukaryotes and these compounds have been related to several intracellular functions, including metal detoxification, homeostasis, metal resistance and protection against oxidative stress. This paper assesses our state of knowledge on the production of PCs and GSH by marine phytoplankton in laboratory and field conditions and the possible applications of PCs for environmental purposes. Good relationships have been observed between metal exposure and PC production in phytoplankton in the laboratory with Cd, Pb, and Zn showing the greatest efficacy, thereby indicating that PCs have a potential for application as a biomarker. Fewer studies on PC distributions in particulate material have been undertaken in the field. These studies show that free Cu has a strong relationship with the levels of PC in the particulate material. The reason for this could be because Cu is a common contaminant in coastal waters. However it could also be due to the lack of measurements of other metals and their speciation. GSH shows a more complex relationship to metal levels both in the laboratory and in the field. This is most likely due to its multifunctionality. However, there is evidence that phytoplankton act as an important source of dissolved GSH in marine waters, which may form part of the strong organic ligands that control metal speciation, and hence metal toxicity. [source] Control of Penicillium roqueforti (Thom) infection in cultures of Drosophila melanogaster (Meigen) (Diptera: Drosophilidae)AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 2 2008Clare E Holleley Abstract, Microbial contamination of artificial insect food media can jeopardise the viability, productivity and survival of many insect cultures, including Drosophila melanogaster. Here we investigated and improved upon control methods for one common contaminant, Penicillium roqueforti. We found that the combined effect of methyl p -hydroxybenzoate (23.7 mM), propionic acid (67.5 mM) and sorbic acid (8.9 mM) (PSNPS treatment) was the most effective of the four candidate treatments, at inhibiting the growth of P. roqueforti. PSNPS treatment inhibited 100% of visible P. roqueforti growth for 21 days (a complete D. melanogaster life cycle) and thus reduced the risk of transmitting infection to the next generation. Although the PSNPS treatment negatively affected the two D. melanogaster fitness components, survivorship (number of adults) and biomass (live weight), it did not prevent successful reproduction and is suitable for short-term treatment of P. roqueforti infections. [source] Simultaneous Quantitative Determination of Cadmium, Lead, and Copper on Carbon-Ink Screen-Printed Electrodes by Differential Pulse Anodic Stripping Voltammetry and Partial Least Squares RegressionELECTROANALYSIS, Issue 23 2008Michael Cauchi Abstract Water is a vital commodity for every living entity on the planet. However, water resources are threatened by various sources of contamination from pesticides, hydrocarbons and heavy metals. This has resulted in the development of concepts and technologies to create a basis for provision of safe and high quality drinking water. This paper focuses on the simultaneous quantitative determination of three common contaminants, the heavy metals cadmium, lead and copper. Multivariate calibration was applied to voltammograms acquired on in-house printed carbon-ink screen-printed electrodes by the highly sensitive electrochemical method of differential pulse anodic stripping voltammetry (DPASV). The statistically inspired modification of partial least squares (SIMPLS) algorithm was employed to effect the multivariate calibration. The application of data pretreatment techniques involving range-scaling, mean-centering, weighting of variables and the effects of peak realignment are also investigated. It was found that peak realignment in conjunction with weighting and SIMPLS led to the better overall root mean square error of prediction (RMSEP) value. This work represents significant progress in the development of multivariate calibration tools in conjunction with analytical techniques for water quality determination. It is the first time that multivariate calibration has been performed on DPASV voltammograms acquired on carbon-ink screen-printed electrodes. [source] Photodegradation of common environmental pharmaceuticals and estrogens in river waterENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2005Angela Yu-Chen Lin Abstract Photodegradation rates of five pharmaceuticals (gemfibrozil, ibuprofen, ketoprofen, naproxen, and propranolol) and of four estrogens (estriol, estrone [E1], 17,-estradiol [E2], and 17,-ethinylestradiol [EE2]), which are common contaminants in the aquatic environment, were measured in both purified and river water at environmentally relevant concentrations (1,2 ,g/L) and different oxygen concentrations. Solutions were irradiated with a xenon arc lamp (765 W/m2; 290 nm < , < 700 nm) and analyzed using a high-performance liquid chromatography-tandem mass spectrometry method with electrospray ionization for pharmaceuticals and atmospheric pressure photoionization for estrogens. In river water, half-lives were 4.1 h for ketoprofen, 1.1 min for propranolol, 1.4 h for naproxen, 2 to 3 h for estrogens, and 15 h for gemfibrozil and ibuprofen. In air-saturated purified water, rates generally were slower except for that of ketoprofen, which reacted with a half-life of 2.5 min. Naproxen, propranolol, and E1 reacted with half-lives of 1.9, 4.4, and 4.7 h, respectively. The EE2, estriol, E2, gemfibrozil, and ibuprofen reacted with half-lives of 28.4, 38.2, 41.7, 91.4, and 205 h, respectively. The presence of oxygen doubled the direct photolysis rates of naproxen and propranolol. In nonautoclaved river water, 80% of E2 rapidly biotransformed to E1 within less than 20 min, whereas all other compounds remained stable over 22 h. [source] Responses of biofilms to combined nutrient and metal exposureENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2002Núria Ivorra Abstract Numerous studies have reported marked sensitivities of diatom species to phosphate and organic pollution but have ignored interactions with other common contaminants. The aim of the present study was to investigate the single and joint effects of increased phosphate and metal (cadmium, zinc) concentrations on benthic diatom communities. Microalgal biofilms from a relatively unpolluted stream were exposed in the laboratory to Zn, Cd, and P, separately and in combination, in concentrations found at a polluted stream in the same catchment. The Zn concentration reduced algal growth in biofilms more than the Cd concentration. Phosphate compensated for the single effect of each metal but not for their combined effects. Diatom community changes were evaluated using water quality indices based on the empirical sensitivities of taxa to nutrients (TDI) and organic pollution (%PTV). Phosphate exposure resulted in an increase of the eutrophy rank and presumed pollution-tolerant taxa. In contrast, exposure to Zn, Zn + Cd, and Zn + Cd + P caused a marked reduction of the TDI and %PTV community values. The successional trends in the laboratory matched the observed differences in microphyte communities in the reference and polluted river stations. However, the autoecology of the species present also revealed that the resulting composition of diatom communities cannot be attributed solely to the direct toxic effects of metal and nutrients and their interaction. Observed changes in the relative abundance of species are also determined by their growth form and microdistribution in biofilms. [source] Methodology and model for performance and cost comparison of innovative treatment technologies at wood preserving sitesREMEDIATION, Issue 1 2001Mark L. Evans Wood preserving facilities have used a variety of compounds, including pentachlorophenol (PCP), creosote, and certain metals, to extend the useful life of wood products. Past operations and waste management practices resulted in soil and water contamination at a portion of the more than 700 wood preserving sites in the United States (EPA, 1997). Many of these sites are currently being addressed under federal, state, or voluntary cleanup programs. The U.S. Environmental Protection Agency (EPA) National Risk Management Research Laboratory (NRMRL) has responded to the need for information aimed at facilitating remediation of wood preserving sites by conducting treatability studies, issuing guidance, and preparing reports. This article presents a practical methodology and computer model for screening the performances and comparing the costs of seven innovative technologies that could be used for the treatment of contaminated soils at user-specified wood preserving sites. The model incorporates a technology screening function and a cost-estimating function developed from literature searches and vendor information solicited for this study. This article also provides background information on the derivation of various assumptions and default values used in the model, common contaminants at wood preserving sites, and recent trends in the cleanup of such sites. © 2001 John Wiley & Sons, Inc. [source] | ||||||||||