Introduction and background Primary producers play critical structural and functional roles in aquatic ecosystems; therefore, it is imperative that the potential risks of toxicants to aquatic plants are adequately assessed in the risk assessment of chemicals. The standard required macrophyte test species is the floating (non-sediment-rooted) duckweed Lemna spp. This macrophyte species might not be representative of all floating, rooted, emergent, and submerged macrophyte species because of differences in the duration and mode of exposure; sensitivity to the specific toxic mode of action of the chemical; and species-specific traits (e.g., duckweed's very short generation time). Discussion and perspectives These topics were addressed during the workshop entitled “Aquatic Macrophyte Risk Assessment for Pesticides” (AMRAP) where a risk assessment scheme for aquatic macrophytes was proposed. Four working groups evolved from this workshop and were charged with the task of developing Tier 1 and higher-tier aquatic macrophyte risk assessment procedures. Subsequently, a SETAC Advisory Group, the Macrophyte Ecotoxicology Group (AMEG) was formed as an umbrella organization for various macrophyte working groups. The purpose of AMEG is to provide scientifically based guidance in all aspects of aquatic macrophyte testing in the laboratory and field, including prospective as well as retrospective risk assessments for chemicals. As AMEG expands, it will begin to address new topics including bioremediation and sustainable management of aquatic macrophytes in the context of ecosystem services.

Introduction In the present work, we explored the kinetics of dichlorvos (2,2-dichlorvinyl dimethyl phosphate, DDVP) decay through UV-A light-induced TiO₂ photocatalysis at pH 4 and 9, and the formation of degradation intermediates and final products under specific experimental conditions. Experimental observations and theoretical considerations allowed us to suggest the degradation mechanism of DDVP by the UV/TiO₂ process in aqueous solution. Methods The irradiation experiments were carried out in a photoreactor using a 228-W medium-pressure Hg vapor lamp. The concentration of DDVP, phosphate ion and formaldehyde as reaction intermediate, are determined spectrophotometrically. Chloride ion concentration was measured potentiometrically. Results The photocatalytic degradation rate of dichlorvos (DDVP) under UV irradiation (360-380 nm) was optimized with respect to the flow rate of O₂ gas sparged into the solution and photocatalyst concentration for a constant dichlorvos concentration (1.66×10⁻⁴ M) at pH 4. Kinetic data were obtained at pH 4 and pH 9 for dichlorvos and the inorganic species released through its photo-induced degradation. The proposed mechanism which assumes the formation of some toxic intermediates resistant to mineralization is supported by theoretical calculations and the observed inorganic mass balances. Conclusions The calculated pseudo-first-order rate constants were dependent on the dissolved oxygen level at low O₂ flow rate, but somewhat independent on the initial pH. The decrease of pH during the irradiation suggests the formation of organic acids. The presence of organic intermediates was confirmed also by TOC measurements. A plausible reaction mechanism of DDVP degradation through the UV-A/TiO₂ process was proposed.

Background, aim and scope The climatic characteristic is a major parameter affecting on the distribution variation of organic pollutants such as polycyclic aromatic hydrocarbons (PAHs). The Tumen River is located in Northeastern of China. The winter era lasts for more than 5 months in a year, and the river water was frozen and covered by ice phase. Coal combustion is an essential heating source in the Tumen River Basin. The objective of this research is to study ice phase effect on the seasonal variation of PAHs in the Tumen River environment. Materials and methods Samples were collected from 13 sites along the River in March, July, October, and December of 2008. In addition, the ice sample, under ice water and air particulate were also collected in winter. The samples were analyzed for 16 PAHs (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, beazo[a]anthene, chrysene, beazo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno(1,2,3-cd)pyrene, dibenz(a,h)anthracene, and benzo(ghi)perylene). The compounds were extracted from the water samples and solid samples using LLE and Soxhlet extraction technique, respectively, and it is determined by gas chromatography-mass spectrometry. Results and discussion Among 16 PAHs, fluorene, phenanthrene, and pyrene were found to be present in high concentrations and at high detection frequencies. The total concentration of PAHs in the water, particulate, sediment and ice phase ranged from 35.1-1.05 × 10³ ng L⁻¹, 25.4-817 ng L⁻¹, 117-562 ng g⁻¹and 62.8-136 ng g⁻¹, respectively. The levels of PAHs were generally higher in spring than other seasons. The ice phase in winter acts like a major reservoir of the pollutants and it is major contributor on the seasonal variation of PAHs in Tumen River. The PAHs found in water, particulate, and sediment in the Tumen River were possibly derived from similar pollution sources a proposition based on the compositions and isomer ratios of PAHs. Conclusions The distribution of PAHs was showed clear seasonal variation in the Tumen River environment, the ice phase and air pollution look like an important factor affecting on the seasonal variation. Recommendations and perspectives The ice phase as an important factor affecting on the seasonal variation of PAHs in Tumen River environment. Further studies regarding the effects of air pollution on the river and the mechanisms of migration and transformation of them in the environment are currently being conducted in our laboratory.

Background, aim, and scope Polysaccharides are renewable resources representing an important class of polymeric materials of biotechnological interest, offering a wide variety of potentially useful products to mankind. Exopolysaccharides (EPSs) of microbial origin with a novel functionality, reproducible physico-chemical properties, stable cost and supply, became a better alternative to polysaccharides of algal origin. EPSs are believed to protect bacterial cells from desiccation, heavy metals or other environmental stresses, including hostimmune responses, and to produce biofilms, thus enhancing the cells chances of colonising special ecological niches. One of the most important stress factor is salt stress for microorganisms. The present investigation is aimed to determine correlation between salt resistance and EPS production by three cyanobacterial isolates (Synechocystis sp. BASO444, Synechocystis sp. BASO507 and Synechocystis sp. BASO511). It is also aimed to investigate the effect of salt concentrations on EPS production by cyanobacteria and effect of salt on monosaccharide composition of EPS. Materials and methods Cyanobacterial isolates were identified by 16 S rRNA analysis. Its salt (NaCl) tolerance and association with exopolysaccharides (EPSs) production in three cyanobacterial isolates were investigated. Also, EPS was analysed by HPLC for monomer characterization. Results Increased EPS production was associated with NaCl tolerance. The most tolerant isolate, Synechocystis sp. BASO444, secreted the most EPS (500 mg/L). EPS production by Synechocystis sp. BASO444, Synechocystis sp. BASO507 and Synechocystis sp. BASO511 was investigated following exposure to 0.2 and 0.4 M NaCl. Also, flasks containing medium without NaCl were inoculated in the same manner to serve as controls. The monosaccharide compositions of EPS produced by the three isolates following exposure to 0.2 M NaCl were analysed by HPLC. Control EPS of BASO444 was composed of glucose (97%) and galacturonic acid (3%). The composition of BASO511 (control) was glucose (95%), xylose (4.80%), arabinose (0.13%), glucuronic acid (0.03%) and galacturonic acid (0.04%). However, the composition of BASO507 (control) was glucose (0.98%), xylose (98.00%), arabinose (1.00%), glucuronic acid (0.01%) and galacturonic acid (0.01%). In the presence of 0.2 M NaCl, EPS compositions and ratios of three cyanobacterial isolates changed. Discussion Although hyperproduction of EPS in response to starvation, antiviral activity, thickening agent and cosmetic industry for product formulations has been reported for cyanobacteria, the effect of NaCl on EPS production in cyanobacteria is not a popular area of study. There are no clear reports correlating EPS production and NaCl tolerance. The gap in the data about the effect of NaCl on cyanobacterial EPS production was filled by this investigation, and the results of our study have important implications in both the industrial and environmental arenas. Conclusions Our results indicate that 1) exposure to elevated concentrations of NaCl affects the composition of EPS produced by Synechocystis sp. BASO444, Synechocystis sp. BASO507 and Synechocystis sp. BASO511, and 2) there is a correlation between NaCl tolerance and EPS production in some cyanobacteria. Recommendations and perspectives Differences in the monosaccharide composition and ratios of EPS may promote NaCl tolerance in these microorganisms. As well, these alternative composition polysaccharides may be important for industrial applications.

Background, aim, and scope Nanomaterials have been used increasingly in industrial production and daily life, but their human exposure may cause health risks. The interactions of nanomaterial with functional biomolecules are often applied as a precondition for its cytotoxicity and organ toxicity where various proteins have been investigated in the past years. In the present study, nano-TiO₂ was selected as the representative of nanomaterials and lysozyme as a representative for enzymes. By investigating their interaction by various instrumentations, the objective is to identify the action sites and types, estimate the effect on the enzyme structure and activity, and reveal the toxicity mechanism of nanomaterial. Materials and methods Laboratory-scale experiments were carried out to investigate the interactions of nano-TiO₂ with lysozyme. The interaction of nano-TiO₂ particles with lysozyme has been studied in the analogous physiological media in detail by UV spectrometry, fluorophotometry, circular dichroism (CD), scanning electron microscope, ζ-potential, and laser particle size. Results The interaction accorded with the Langmuir isothermal adsorption and the saturation number of lysozyme is determined to be 580 per nano-TiO₂ particle (60 nm of size) with 4.7 × 10⁶ M⁻¹ of the stability constant in the physiological media. The acidity and ion strength of the media obviously affected the binding of lysozyme. The warping and deformation of the lysozyme bridging were demonstrated by the conversion of its spatial structure from α-helix into a β-sheet, measured by CD. In the presence of nano-TiO₂, the bacteriolysis activity of lysozyme was subjected to an obvious inhibition. Discussion The two-step binding model of lysozyme was proposed, in which lysozyme was adsorbed on nano-TiO₂ particle surface by electrostatic interaction and then the hydrogen bond (N-H···O and O-H···O) formed between nano-TiO₂ particle and polar side groups of lysozyme. The adsorption of lysozyme obeyed the Langmuir isothermal model. The binding of lysozyme is dependent on the acidity and ion strength of the media. The bigger TiO₂ aggregate was formed in the presence of lysozyme where lysozyme may bridge between nano-TiO₂ particles. The coexistence of nano-TiO₂ particles resulted in the transition of lysozyme conformation from an α-helix into a β-sheet and a substantial inactivation of lysozyme. The β-sheet can induce the formation of amyloid fibrils, a process which plays a major role in pathology. Conclusions Lysozyme was adsorbed on the nano-TiO₂ particle surface via electrostatic attraction and hydrogen bonds, and they also bridged among global nano-TiO₂ particles to form the colloidal particles. As a reasonable deduction of this study, nano-TiO₂ might have some toxic impacts on biomolecules. Our data suggest that careful attention be paid to the interaction of protein and nanomaterials. This could contribute to nanomaterial toxicity assessment. Recommendations and perspectives Our results strongly suggest that nano-TiO₂ has an obvious impact on biomolecules. Our data suggest that more attention should be paid to the potential toxicity of nano-TiO₂ on biomolecules. Further research into the toxicity of nanosized particles needs to be carried out prior to their cell toxicity and tissue toxicity. These investigations might serve as the basis for determining the toxicity and application of nanomaterials.

Background, aim, and scope Due to the active production and transport of crude oil in the Arabian Gulf region, the Arabian Gulf coasts are routinely polluted with oil. Therefore, such coasts have been subject of studies aiming at assessing the roles of indigenous microbial consortia in cleaning these environments. In the present study, epilithic microbial communities along Kuwait coasts were studied for their oil degradation potential. Materials and methods Gravel particles coated with deep green biofilms were collected from four coastal sites in autumn, winter, and spring. Phototrophs in these consortia were determined in terms of their chlorophyll a contents and identified by their morphological characteristics. Total bacteria were counted microscopically and cultivable bacteria by the dilution plating method on nutrient agar as well as on inorganic medium containing oil as a sole source of carbon and energy. The bacterial community structures were also characterized and compared by denaturing gradient gel electrophoresis (DGGE). Results Epilithic biomass samples from the four sites in the three seasons were rich in diatoms and picocyanobacteria as well as total bacteria. Direct counting gave bacterial numbers per square centimeter gravel surface of 2 to 6 × 10⁷ cells depending on the sampling site and season. Cultivable bacterial numbers on nutrient agar and crude oil as a sole source of carbon were 3 × 10³ to 8 × 10⁴ and 1 × 10³ to 7 × 10³ cells/cm² gravel surface, respectively. The DGGE profiles of epilithon biomass samples revealed major 16S rDNA bands that matched bands of pure oil-utilizing bacterial isolates. Discussion The microbial communities showed a degree of consistency in all sites and seasons. Conclusions The microbial consortia coating gravel particles are potentially suitable tools for self-cleaning of oily Gulf coasts. They are rich in oil-utilizing bacteria whose activities are probably enhanced by oxygen produced by the phototrophic partners in the consortia. Recommendations and perspectives The combination of conventional microbiological analysis with molecular approaches gives an enhanced idea about natural microbial communities especially those with environmental application potential.

Background, aim, and scope For many years, highly concentrated wastewater generated from the pulp and paper industry has become the focus of much concern worldwide. The objectives of this study were to determine the treatment efficiency of the alkaline peroxide mechanical pulp (APMP) process wastewater using a sequencing batch reactor (SBR) and analyze the microbial dynamics of the wastewater treatment system using the random amplified polymorphic DNA (RAPD) method. Materials and methods An SBR was applied to the treatment of APMP pulp and paper process wastewater. The wastewater characteristics and many physicochemical operator indicators in the wastewater treatment process were analyzed and determined according to standard methods. Microbial 16 S rDNA in active sludge was extracted, amplified, and analyzed using the RAPD method for the microbial dynamics of the wastewater treatment system. Results and discussion Ten kinds of natural organic compounds of plants such as monoterpene were detected in the APMP pulp and paper process wastewater. With an influent chemical oxygen demand (COD) that varied in the range of 685.7 to 907.5 mg/L, the corresponding effluent COD was 176.5 to 266.1 mg/L and the removal efficiency was 70.3% to 79.8%. An optimal strain (S308: CAGGGGTGGA) was selected to study the population dynamics and diversity of the bacterial community. The RAPD-polymerase chain reaction (PCR) fingerprints showed very high polymorphism of the genetic bands (78-100%). Four groups of species were clustered using the unweighted pair group method with arithmetic (UPGMA) analysis, and the genetic distance was close between the species within each group. The Shannon-Weaver index was high and varied over time with the COD removal. Conclusions The RAPD-PCR technique can be used to study microbial dynamics, which was shown to vary over time with the removal efficiency of SBR treating APMP pulp and paper process wastewater.

Background, aim and scope For reliable environmental risk assessment of pollutants, knowledge on the effects at different levels of biological organisation is needed. During the early days of biomarker research in environmental studies approximately two decades ago, biochemical biomarkers were considered as the most promising tool for such purposes. Among these, three enzymes have often been studied: catalase (CAT), glutathione S-transferase (GST) and cholinesterase (ChE). However, despite their intensive research, their measurements in invertebrates have not been commonly applied in environmental risk assessment (ERA) or for regulatory purposes. Main features In the present review, we summarise our past experiences in biochemical biomarker research in two crustacean species: water flea Daphnia magna and terrestrial isopod Porcellio scaber. This is to orientate their use and to provide recommendations for the use of novel biomarkers in environmental studies, such as proteomic or genomic responses. Results and discussion We assessed the intrinsic properties of biochemical biomarkers CAT, GST and ChE in the D. magna and the isopod P. scaber. It was found that they are not in agreement with the expectations that were previously given for their use in environmental studies. To advance their use in environmental risk assessment, we suggest that based on their properties, their role should be more specifically defined. ERA includes several distinct steps, among them hazard identification, effect assessment and finally risk characterisation, each of which requires a different type of toxicity data. We recommend that the use of biochemical markers is most appropriate for hazard identification because this is a procedure whose purpose is to characterise the potential hazard of the substance in question and is more flexible in terms of using different tools. Furthermore, our results imply that biochemical markers are not always more sensitive than whole-organism responses, as was anticipated. Their sensitivity depends on the mode of action, duration of exposure and test species. Therefore, we suggest that combining both a battery of biomarkers from different levels of biological organisation and an array of biomarkers within a single level could identify hazard adequately. Conclusions The lesson learnt from biochemical biomarkers in environmental studies utilizing crustacean model species is that, for successful application of each group of biomarkers, their intrinsic properties are needed to be known before an (eco)toxicity study is designed. We suggest that a substantial body of experience obtained with biochemical biomarkers should be exploited to new emerging biomarkers in environmental studies in order to facilitate their application. Recommendations and perspectives The future of biomarkers lies in a combination of traditional biochemical and new-generation biomarkers. The latter are not only a potential replacement for existing biomarkers but will also provide new knowledge which might encourage renewed research and development of traditional biomarkers. For research purposes, complete ecotoxicity information should include contributions from molecular fingerprint of an organism, as well as whole organism, population and ecosystem responses. Still, the type of biomarkers used for routine purposes will depend on their reproducibility, their ease of use, robustness, affordability of the methodology and the type of chemicals, organisms and ecosystem of interest.

Bitumen is a black, thermoplastic, hydrocarbon material derived from the processing of crude oil. At ambient temperature, bitumen is solid and does not present any health/environmental risks. This is one of the main reasons that bitumen is widely used for road construction all over the world. But during manufacturing/modification according to its application, storage, transportation, and use of bitumen is heated giving off various hydrocarbons emissions. In recent years, there has been increasing interest in investigating the potential of bitumen emissions to cause health effects. This is mainly because of the reason that bitumen has small amount of poly-aromatic hydrocarbons, along with some other volatiles like benzene, toluene, etc., which are known to be carcinogenic in nature. Thus, assessment of the emission characteristics and health hazards of bitumen fumes may have far reaching industrial economic and public health implications. In this review, we will discuss about the emission characteristics from bitumen, asphalts, or road construction, which is mainly contributed by bitumen fumes. Sampling strategies and analytical methods employed are also described briefly.

Background, aim, and scope Lead, a major contaminant, is highly used in paint manufacturing due to its anticorrosive properties. Recent reports indicated high lead content among Indian paints used for commercial purposes. Painters are continuously exposed to these lead containing paints during painting of both commercial as well as residential buildings. Lead is well-known for its genotoxicty in occupational workers; however, in Indian painters the genotoxic effects of lead have not been reported to date. Therefore we aimed to study the genotoxic end points in painters due to their long-term exposure to these high lead-containing Indian paints. Materials and methods Study group selection was made after a questionnaire administration, which included questions about lifestyle and medical history to exclude exposure to the other potential sources of genotoxics. Blood and buccal cell samples were obtained from 30 male painters and from a similar number of age-matched controls of same location with no occupational exposure to lead. Blood lead levels (Pb-B) were measured in painters and controls. Micronucleus (MN) frequencies and nuclear changes, i.e., karyorrhexis, karyolysis, broken egg, and binucleated, were investigated in buccal epithelial cells. Results Painters had significantly (P < 0.01) greater lead levels in blood than the control group. MN frequencies and nuclear changes in buccal epithelial cells were also significantly (P < 0.01) elevated in painters as compared with control subjects. Regression analysis also revealed significant (P < 0.01) association of Pb-B with all the genotoxic endpoints in painters. Cytogenetic damage was significantly associated with Pb-B as no other co-founding factors (smoking, alcohols) showed significant difference between both groups. Discussion Lead is widely used in paints which may serve as potential source of exposure among painters due to their long-term engagement with paints. Our results clearly demonstrated genotoxicity among the exposed population as evident from increase micronucleus frequencies, frequent nuclear changes, and apoptosis. Many studies had previously related nuclear change events in buccal epithelial cells with the progression of different carcinomas. Furthermore in-depth investigations with larger sample size are needed to provide evidence to this effect. Conclusions Here, we report cytogenetic toxicity to the exposed population by the high lead containing paints from India for the first time. Frequent, high and unregulated use of lead in paints may cause genetic mutation and may accelerate cytogenetic damage which may further lead to different carcinomas in painters. These findings need to be considered and necessary steps should be taken to protect the occupational workers engaged with these high lead-containing paints. Recommendations The use of lead in paints is completely unregulated in India and routine surveillance of paints for lead content is still lacking. These paints are readily available in markets and are also used in other products (jewelry, miniblinds) which could be exported to other countries including United States and Europe. Serious consideration should be given to the inclusion of regulations and bans on the use of lead in paints. Moreover, attention should also be paid towards the use of various protective measures (face-masks, hand gloves, and separate clothes) by the workers as safe work practices during working periods.