Adjusting the effect of seasonal variability in the bioassessment of streams

Bioassessment tools should distinguish between the effects of anthropogenic degradation in communities and natural temporal changes. The present study tests the influence of natural seasonal variability on macroinvertebrate stream communities assessed by a predictive model (PORTRIV) and a multimetric index (IPtI) calibrated for spring. The scores of PORTRIV decreased significantly between spring and autumn, and between spring and winter (ca. 37 to 53 %, respectively), while those of IPtI did not change significantly between seasons. For non-reference samples, the results of the predictive model also indicate no significant differences. A correction factor (CF) was calculated to adjust the existing differences in the model assessments between seasons, based on the percentage of variation of reference site scores from spring to autumn and winter. After the application of the CF to the OE50 scores of spring reference samples, the differences were no longer significant. Independent reference validation sites confirmed this tendency. This method has the advantage of avoiding large efforts required for the construction of databases from other seasons and the development of new models to allow the assessment of streams in seasons other than spring. Further tests with models developed in regions with more marked seasonal changes should be done to confirm its wider applicability.     

DNA damage as a biomarker of genotoxic contamination in Mytilus galloprovincialis from the south coast of Portugal

DNA damage was evaluated in the haemolymph of Mytilus galloprovincialis from nine sites along the south coast of Portugal using the comet assay. DNA damage was low, in the same range of sites considered to suffer low impact from genotoxic contaminants. Even so, differences between sites, seasons and genders were found. Highest values were in mussels from the main estuaries and the fishery harbour, reflecting higher genotoxin levels, whereas the lowest values can be used as a baseline for future work. Non-contaminant related factors (e.g. temperature and oxygen) were also shown to influence DNA damage. Between seasons, highest values were in summer related not only to the increase of tourism in this region (～10-fold), but also to temperature. Between genders, males were found to be more sensitive. The condition index was also generally higher in summer. Lipid peroxidation, another damage biomarker, was measured in gills to assess if there is any association between the responses of both biomarkers and if they are similarly affected by the same environmental conditions. LPO like DNA damage was higher in summer. This work confirms that DNA damage is a sensitive biomarker to discriminate genotoxic contamination, even in areas considered to suffer low impact from genotoxins.     

Optical fiber based methodology for assessment of thiocyanate in seawater

A new methodology for the assessment of thiocyanate (SCN(-)) is proposed based on optical fiber (OF) detection coupled to a liquid chromatography system (LC). The developed methodology showed an adequate performance for the analysis of SCN(-) comparable to a high performance liquid chromatography with UV detector (HPLC-UV) methodology: a detection limit of 3 μg L(-1), a linear range from 4 to 400 μg L(-1), and an analytical time of less than 6 min. The OF based methodology was of compact design and easy operation. This simple system has the potential to be used as a sensing approach for SCN(-) in seawater.     

Phytoplankton and water quality in a Mediterranean drinking-water reservoir (Marathonas Reservoir, Greece)

Phytoplankton and water quality of Marathonas drinking-water Reservoir were examined for the first time. During the study period (July-September 2007), phytoplankton composition was indicative of eutrophic conditions although phytoplankton biovolume was low (max. 2.7 mm3 l?1). Phytoplankton was dominated by cyanobacteria and diatoms, whereas desmids and dinoflagellates contributed with lower biovolume values. Changing flushing rate in the reservoir (up to 0.7% of reservoir's water volume per day) driven by water withdrawal and occurring in pulses for a period of 15-25 days was associated with phytoplankton dynamics. Under flushing pulses: (1) biovolume was low and (2) both 'good' quality species and the tolerant to flushing 'nuisance' cyanobacterium Microcystis aeruginosa dominated. According to the Water Framework Directive, the metrics of phytoplankton biovolume and cyanobacterial percentage (%) contribution indicated a moderate ecological water quality. In addition, the total biovolume of cyanobacteria as well as the dominance of the known toxin-producing M. aeruginosa in the reservoir's phytoplankton indicated a potential hazard for human health according to the World Health Organization.     

Design and laboratory testing of a new flow-through directional passive air sampler for ambient particulate matter

A new type of directional passive air sampler (DPAS) is described for collecting particulate matter (PM) in ambient air. The prototype sampler has a non-rotating circular sampling tray that is divided into covered angular channels, whose ends are open to winds from sectors covering the surrounding 360°. Wind-blown PM from different directions enters relevant wind-facing channels, and is retained there in collecting pools containing various sampling media. Information on source direction and type can be obtained by examining the distribution of PM between channels. Wind tunnel tests show that external wind velocities are at least halved over an extended area of the collecting pools, encouraging PM to settle from the air stream. Internal and external wind velocities are well-correlated over an external velocity range of 2.0-10.0 m s?1, which suggests it may be possible to relate collected amounts of PM simply to ambient concentrations and wind velocities. Measurements of internal wind velocities in different channels show that velocities decrease from the upwind channel round to the downwind channel, so that the sampler effectively resolves wind directions. Computational fluid dynamics (CFD) analyses were performed on a computer-generated model of the sampler for a range of external wind velocities; the results of these analyses were consistent with those from the wind tunnel. Further wind tunnel tests were undertaken using different artificial particulates in order to assess the collection performance of the sampler in practice. These tests confirmed that the sampler can resolve the directions of sources, by collecting particulates preferentially in source-facing channels.     

Morphological abnormalities in frogs from a rice-growing region in NSW, Australia, with investigations into pesticide exposure

Three frog species (Limnodynastes tasmaniensis, Limnodynastes fletcheri and Litoria raniformis) were surveyed in rice bays of the Coleambally Irrigation Area (CIA), NSW, Australia, during the rice-growing seasons of 2005/2006 and 2006/2007. A total external morphological abnormality index of 7.0% was observed in frogs of the CIA (n?=?1,209). The types and frequencies of abnormalities were typical of reports from agricultural areas with ectrodactyly being the most common aberration. A relatively low abnormality index of 1.2% was observed in L. raniformis (n?=?87) compared to indices of 7.1% and 8.2% observed in L. fletcheri (n?=?694) and L. tasmaniensis (n?=?428), respectively. No conclusive evidence was found of unnaturally high rates of intersex, gonadal maldevelopment or unbalanced sex ratios in any species. Rice bay surface waters differed significantly in mean pesticide concentrations of atrazine and metolachlor on farms growing rice and corn compared to farms with rice as the sole crop. However, the similar abnormality indices observed in recent metamorphs emerging from these two farm types provided no evidence to suggest a link between larval exposure to the measured pesticides and developmental malformations.     

Evaluation of toxic metal (Hg, Cd, Pb), polychlorinated biphenyl (PCBs), and pesticide (DDTs) levels in aromatic herbs collected in selected areas of Southern Italy

This study provides, for the first time, data regarding levels of toxic metals (Hg, Cd, and Pb) and organochlorine compounds (PCBs and DDTs) in various aromatic herbs as rosemary (Rosmarinus officinalis), sage (Salvia officinalis), laurel (Laurus nobilis), oregano (Origanum vulgare), and spearmint (Mentha viridis) collected in some towns of the Southern Italy with different anthropogenic and population pressure. Metal and organochlorine compound concentrations were determined using atomic absorption spectrophotometer and gas-chromatography mass spectrometer (GC/MS), respectively. Pb emerged as the most abundant element, followed by Cd and Hg, while between organochlorine compounds, PCB concentrations were higher than those of DDTs. The pollutant concentrations were found to vary depending on the different herbs. The highest Pb levels were observed in rosemary (1.66 μg g^?1 dry weight) and sage (1.41 μg g^?1 dry weight), this latter showing also the highest Cd concentrations (0.75 μg g^?1 dry weight). For PCBs, the major concentrations were found in rosemary (2.75 ng g^?1 dry weight) and oregano (2.39 ng g^?1 dry weight). The principal component analysis applied in order to evaluate possible similarities and/or differences in the contamination levels among sampling sites indicated differences area-specific contamination.     

Photocatalytic degradation of acetaminophen in modified TiO2 under visible irradiation

This study investigated the photocatalytic degradation of acetaminophen (ACT) in synthetic titanium dioxide (TiO₂) solution under a visible light (λ >440 nm). The TiO₂ photocatalyst used in this study was synthesized via sol–gel method and doped with potassium aluminum sulfate (KAl(SO₄)₂) and sodium aluminate (NaAlO₂). The influence of some parameters on the degradation of acetaminophen was examined, such as initial pH, photocatalyst dosage, and initial ACT concentration. The optimal operational conditions were also determined. Results showed that synthetic TiO₂ catalysts presented mainly as anatase phase and no rutile phase was observed. The results of photocatalytic degradation showed that LED alone degraded negligible amount of ACT but with the presence of TiO₂/KAl(SO₄)₂, 95 % removal of 0.10-mM acetaminophen in 540-min irradiation time was achieved. The synthetic TiO₂/KAl(SO₄)₂ presented better photocatalytic degradation of acetaminophen than commercially available Degussa P-25. The weak crystallinity of synthesized TiO₂/NaAlO₂ photocatalyst showed low photocatalytic degradation than TiO₂/KAl(SO₄)₂. The optimal operational conditions were obtained in pH 6.9 with a dose of 1.0 g/L TiO₂/KAl(SO₄)₂ at 30 °C. Kinetic study illustrated that photocatalytic degradation of acetaminophen fits well in the pseudo-first order model. Competitive reactions from intermediates affected the degradation rate of ACT, and were more obvious as the initial ACT concentration increased.