12,835 research outputs found
Surveillance of adenoviruses and noroviruses in European recreational waters
No full textExposure to human pathogenic viruses in recreational waters has been shown to cause disease outbreaks. In the context of Article 14 of the revised European Bathing Waters Directive 2006/7/EC (rBWD, CEU, 2006) a Europe-wide surveillance study was carried out to determine the frequency of occurrence of two human enteric viruses in recreational waters. Adenoviruses were selected based on their near-universal shedding and environmental survival, and noroviruses (NoV) selected as being the most prevalent gastroenteritis agent worldwide. Concentration of marine and freshwater samples was done by adsorption/elution followed by molecular detection by (RT)-PCR. Out of 1410 samples, 553 (39.2%) were positive for one or more of the target viruses. Adenoviruses, detected in 36.4% of samples, were more prevalent than noroviruses (9.4%), with 3.5% GI and 6.2% GII, some samples being positive for both GI and GII. Of 513 human adenovirus-positive samples, 63 (12.3%) were also norovirus-positive, whereas 69 (7.7%) norovirus-positive samples were adenovirus-negative. More freshwater samples than marine water samples were virus-positive. Out of a small selection of samples tested for adenovirus infectivity, approximately one-quarter were positive. Sixty percent of 132 nested-PCR adenovirus-positive samples analysed by quantitative PCR gave a mean value of over 3000 genome copies per L of water. The simultaneous detection of infectious adenovirus and of adenovirus and NoV by (RT)PCR suggests that the presence of infectious viruses in recreational waters may constitute a public health risk upon exposure. These studies support the case for considering adenoviruses as an indicator of bathing water quality
Geochemistry of As-, F- and B-bearing waters in and around San Antonio de los Cobres, Argentina, and implications for drinking and irrigation water quality
No full textSpring, stream and tap waters from in and around San Antonio de los Cobres, Salta, Argentina, were sampled to characterize their geochemical signatures, and to determine whether they pose a threat to human health and crops. The spring waters are typical of geothermal areas world-wide, in that they are Na-Cl waters with high concentrations of Astot, As(III), Li, B, HCO3, F and SiO2 (up to 9.49, 8.92, 13.1, 56.6, 1250, 7.30 and 57.2 mg L-1, respectively), and result from mixing of deep Na-Cl brines and meteoric HCO3-rich waters. Springs close to the town of San Antonio have higher concentrations of all elements, and are generally cooler, than springs in the Baños de Agua Caliente. Spring water chemistry is a result of mixing of deep Na-Cl brines and meteoric HCO3 waters. Stream waters are also Na-Cl type, and receive large inputs of all elements from the springs near San Antonio, but concentrations decrease downstream through the town of San Antonio due to mineral precipitation. The spring that is used as a drinking water source, and other springs in the area, have As, F and B concentrations in excess of WHO and Argentinian drinking water guidelines. Evaluation of the waters for irrigation purposes suggests that their high salinities and B concentrations may adversely affect crops. The waters may be improved for drinking and irrigation by dilution with cleaner meteoric waters, mineral precipitation or by use of commercial filters. Such recommendations could also be followed by other settlements that draw drinking and irrigation waters from geothermal sources
Taxonomy of the fouling cheilostome bryozoans, Schizoporella unicornis, (Johnston) and Schizoporella errata (Waters)
No full textFigure 1. (A–D) Images of Wood's Pliocene specimen from the Coralline Crag, Suffolk (NHM B1675) described in Busk (1859). (A) Group of autozooids at growing edge of colony within small bivalve shell. (B) Autozooids exhibiting deep V-shaped sinus. (C) Frontal shield with paired avicularia and deep V-shaped sinus. (D) Detail of primary orifice and sinus. (E, F) Lectotype of Schizoporella unicornis [NHM 1847.16.174 (a)] bleached portion. (E) Group of autozooids at the distal edge of colony with adventitious avicularia, paired, single or absent. (F) Ovicellate autozooids showing radially aligned scalloped grooves. Scale bars: 500 µm (A); 250 µm (B); 100 µm (C, E); 50 µm (D,F).Published as part of Tompsett, Scott, Porter, Joanne S. & Taylor, Paul D., 2009, Taxonomy of the fouling cheilostome bryozoans Schizoporella unicornis (Johnston) and Schizoporella errata (Waters), pp. 2227-2243 in Journal of Natural History 43 (35-36) on page 2231, DOI: 10.1080/00222930903090140, http://zenodo.org/record/521715
Geochemical and Isotopic Composition of Natural Waters in the Central Main Ethiopian Rift: emphasis on the study of source and genesis of fluoride
No full textIn the Main Ethiopian Rift (MER), the supply of drinking water principally relies on groundwater wells,
springs (including some hot springs), and rivers, and is characterized by a significant problem of
fluoride (F¯) contamination. New analyses reveal that the F− geochemical anomaly is sometimes
associated with hazardous content of other potentially toxic elements such as As, B, Mo, U, Al, Fe, and
Mn. The F¯ content exceeds the permissible limit for drinking prescribed by the World Health
Organization (WHO; 1.5 mg/L) in many important wells (up to 20 mg/L), with even more extreme F
concentration in hot springs and alkaline lakes (up to 97 mg/L and 384 mg/L respectively) and is
causing prevalent endemic fluorosis disease in the region.
87 % of the groundwater wells, 38 % of rivers and 100 % of hot springs and lakes show F¯ content
above 1.5 mg/L. The groundwater and surface water from the highlands, typically characterized by low
Total Dissolved Solids (TDS) and Ca2+ (Mg2+)-HCO3¯ hydrochemical facies, do not show high F¯
content. The subsequent interaction of these waters with the various rocks of the rift valley induces a
general increase of the TDS and a variation of the chemical signature towards Na+-HCO3¯
compositions, with a parallel enrichment of F¯. The interacting matrixes are mainly rhyolites consisting
of volcanic glass and only rare F-bearing accessory minerals (such as alkali amphibole).
Comparing the abundance and the composition of the glassy groundmass with other mineral phases, it
appears that the former stores most of the total F¯ budget. This glassy material is extremely reactive,
and its weathering products (i.e. fluvio/volcano-lacustrine sediments) further concentrate the fluoride.
The interaction of these “weathered/reworked” volcanic products with water and carbon dioxide at high
pH causes the release of fluoride into the interacting water. This mainly occurs by a process of baseexchange
softening with the neo-formed clay minerals (i.e. Ca-Mg uptake by the aquifer matrix, with
release of Na+ into the groundwater). This is plausibly the main enrichment mechanism that explains
the high F¯ content of the local groundwater, as evidenced by positive correlation between F¯, pH, and
Na+, and inverse correlation between F¯ and Ca2+ (Mg2+). Saturation indices (SI) were calculated (using
PHREEQC-2) for the different water groups, highlighting that the studied waters are undersaturated in
fluorite. In these conditions, fluoride can not precipitate as CaF2, and so F¯ mobilizes freely without
forming other complexes.
On the other hand, 35 % of the 23 investigated groundwater wells and 70 % of the 12 hot springs (and
deep geothermal wells) show Arsenic concentration above the recommended limit of 10μg/L (WHO
2006). The average concentration of Arsenic is 0.9μg/L in rivers, 39μg/L in hot springs, 236μg/L in
deep geothermal wells, 21.4μg/L in groundwater wells, 77μg/L in lakes, whereas maximum
concentrations reach up to 3μg/L, 156μg/L, 278μg/L, 157μg/L and 405 μg/L respectively. Arsenic in
groundwater wells shows positive correlations with Na+ (R2=0.63) and HCO3
− (R2=0.70) as well as with
other trace elements such as Mo (R2=0.79), U (R2=0.70), V (R2=0.68) whereas no correlations are
observed with Fe and Mn. PHREEQC speciation modelling indicates that Fe and Al oxides and
hydroxides are stable in the water systems, suggesting that Fe and Al mineral phases are potential
adsorbents and thus influence the mobility of As. The oxidizing, high pH condition combined with Na+-
HCO3¯ hydrochemical facies (competing effect of HCO3
− for adsorption sites) of the MER waters play
an important role in the mobilization of arsenic.
Chemical analyses of leachates from MER rhyolitic rocks and their weathered and reworked fluviolacustrine
sediments were performed in order to evaluate their contribution as a source of the mentioned
geochemical anomalies. The leachates were obtained from a one-year leaching experiment on powdered
rocks and sediments mixed with distilled water (10g:50ml). The sediment leachates contain as much as
7.6 mg/L of F¯, 220 μg/L of As, 181 μg/L of Mo, 64 μg/L of U and 254 μg/L of V suggesting that the
local sediments represent the main source and reservoir of toxic elements. Laboratory column
experiment was also conducted in volcanic ash sample using synthetic rain water flushing, and the result
showed that significant amount of F¯ were leached out over the duration of the experiments.
This showed that these elements were originally present in the glassy portion of the MER rhyolitic
rocks, were progressively concentrated in weathered and redeposited products. It further confirms that
the pyroclastic materials are the major source and reservoir of many of the chemical elements (e.g. F¯,
As). Therefore, together with the renowned F¯ problem, the possible presence of geochemical
anomalies in As, B, Mo, V, U, Al, Fe, and Mn have to be taken into consideration in water quality issues
and future works has to investigate their possible health impact on the population of MER and other
sectors of the east African rift.
The stable δ18O, δD and radiogenic (87Sr/86Sr) isotopic composition of waters and representative
volcanic rocks (Ignimbrite and basalt) were carried out during this study. Different ranges of isotopic
values were recorded for different water groups: 10 hot spring samples show δ18O value with in the range of (-3.36‰ – 3.69‰) and δD (-0.95‰ – 24.23‰) (VSMOW), 12 groundwater wells δ18O (-
3.99‰ – 5.14‰) and δD (-19.69‰ – 32.27‰) in contrast to the 5 Lakes δ18O (3.98‰ – 7.92‰) and δD
(26.19‰ – 45.71‰). The 2 deep geothermal wells and 1 of the 2 river samples are depleted in stable
isotopic values. 87Sr/86Sr values range from 0.7045 to 0.7076 in the hot springs, and the two deep
geothermal wells have 0.7043 and 0.7054 values. These signatures are typical of water interacted with
mantle derived materials (with a minor crustal contamination), similar to the rocks widely covering the
study area. The Sr isotope values of the basalt and ignimbrite samples are 0.7063 and 0.7071
respectively. Generally, the result shows that there exists a complex surface water and groundwater
interactions that is reflected on a diversity of the stable and Sr isotopic signature in waters.
The preliminary results of the study has showed that there is a need for future extended works on the
geochemistry of solid samples (rocks, sediments and soils) as well as in waters that investigate all the
spectrum of chemical elements that are potentially detrimental to human health and environment.
Furthermore, from water resource point of view, the following works must focus on a comprehensive
study of various isotopes and geochemical data to constrain groundwater age dating, water-rock
interaction and flow path and thus help to model and systematize the hydrologic cycles in the basin
Evaluation of a Smectite Adsorption-Based Electrostatic System to Decontaminate F− Rich Thermal Waters
No full textSeveral studies have shown the presence of fluoride levels much higher than the 1.5 mg/L threshold concentration recommended by WHO in the spring waters and wells of the Ethiopian Rift Valley. Available defluoridation techniques can be costly, present complicated technical aspects, and show limited effectiveness. Therefore, it is necessary to devise innovative, sustainable, and effective solutions. This study proposes an alternative method of intervention to the known techniques for removing fluoride from water, particularly suitable for smaller rural communities. In particular, in this work, the possibility to use electromagnetic fields as a physical method for removing the excess fluoride was investigated. The study was carried out by developing a multiphysics model used for studying and envisaging the design of a device. In this framework, the combination of this approach with the use of highly reactive smectite clay was numerically studied. The results obtained, although preliminary, indicate that the proposed system could significantly impoverish the waters of the Rift Valley from fluoride, with the consequence of obtaining a resource suitable for human consumption, in particular for rural communities. However, further theoretical investigations and experimental phases will be necessary to achieve the desired results
Biogeography of Wood-Boring Crustaceans (Isopoda: Limnoriidae) Established in European Coastal Waters
No full textMarine wood-borers of the Limnoriidae cause great destruction to wooden structures exposed in the marine environment. In this study we collated occurrence data obtained from field surveys, spanning over a period of 10 years, and from an extensive literature review. We aimed to determine which wood-boring limnoriid species are established in European coastal waters; to map their past and recent distribution in Europe in order to infer species range extension or contraction; to determine species environmental requirements using climatic envelopes. Of the six species of wood-boring Limnoria previously reported occurring in Europe, only Limnoria lignorum, L. quadripunctata and L. tripunctata are established in European coastal waters. L. carinata and L. tuberculata have uncertain established status, whereas L. borealis is not established in European waters. The species with the widest distribution in Europe is Limnoria lignorum, which is also the most tolerant species to a range of salinities. L. quadripunctata and L. tripunctata appear to be stenohaline. However, the present study shows that both L. quadripunctata and L. tripunctata are more widespread in Europe than previous reports suggested. Both species have been found occurring in Europe since they were described, and their increased distribution is probably the results of a range expansion. On the other hand L. lignorum appears to be retreating poleward with ocean warming. In certain areas (e.g. southern England, and southern Portugal), limnoriids appear to be very abundant and their activity is rivalling that of teredinids. Therefore, it is important to monitor the distribution and destructive activity of these organisms in Europe
Ichthyoplankton assemblages associated with pink snapper (Pagrus auratus) spawning aggregations in coastal embayments of southwestern Australia
No full textPink snapper (Pagrus auratus) form spawning aggregations during the austral spring/summer in three adjacent, sheltered, coastal embayments in southwestern Australia (Cockburn Sound, Warnbro Sound and Owen Anchorage). Larval fishes were sampled in these embayments, as well as in the more exposed adjacent waters of Five Fathom Bank, to ascertain which teleost species utilised these areas for spawning concurrently with P. auratus. Obliquely towed bongo nets (500 μm mesh) were used to collect icthyoplankton in November 2007 over three days during the new moon period when spawning of P. auratus is known to peak. A total of 13 270 larvae from 30 teleost families was collected with an overall mean larval fish concentration of 1.91 m -3 (± s.e. 0.28). Larval fish assemblages were significantly different in each of the three embayments and Five Fathom Bank, reflecting the degree of shelter, water-circulation patterns and associated benthic habitats. The highest larval fish concentrations were recorded in Cockburn Sound (3.69 m -3 ± s.e. 0.05) and the lowest along Five Fathom Bank (0.16 m -3 ± s.e. 0.02). P. auratus larvae were only present in samples from the three embayments. The most abundant larvae were those of the Australian anchovy (Engraulis australis), which occurred predominantly in Cockburn Sound and, to a lesser extent, Owen Anchorage. The most ubiquitous larvae included the longspine dragonet (Callionymus goodladi) and leatherjackets (Monacanthidae). This study provides circumstantial evidence that eggs and larvae of P. auratus and other teleosts are retained in the sheltered waters of Cockburn and Warnbro Sounds during spring/summer
Combined continuous electrical tomography and very high resolution seismic surveys to assess continental and marine groundwater mixing
No full textSalt contamination in the coastlands surrounding Venice Lagoon (Italy) and Laizhou Bay (Shandong Province, China) is generally the result of the complex relationship between fresh, continental groundwaters, paleo-saltwaters in deep aquifers, marine waters, and the seawater encroachment upstream from the river mouths. Saltwater intrusion is also enhanced by the presence of ancient, sandy, buried paleo-channels that act as preferential pathways for groundwater flow and solute transport. The characterization of these hydro-geo-morphological features, considering both the architecture and the pore water quality, is an issue of paramount importance. In this work, after a short overview of the saltwater contamination occurrence that affects the coastlands of Venice Lagoon and Laizhou Bay, we report on the preliminary results of a Very High Resolution Seismic and Continuous Electrical Tomography test carried out in very shallow water (about 1 m) in the Venice Lagoon to test a technique suitable for the better understanding of the surficial-groundwater mixing process. The combined analysis of the two data sets highlights a correlation between lithostratigraphic discontinuities and heterogeneity in the fluid filling the subsurface. The promising results obtained in the Italian site support a prompt use of this integrated methodology on the Chinese study area too
Rhamnolipids as an alternative fungicide against plant pathogens.
No full textRhamnolipids are potent natural glycolipid biosurfactants often biosynthesized by Pseudomonas aeruginosa strains through the fermentation process. As biologically produced molecules, Rhamnolipids are generally reported to have less impact on the environment than conventional surfactants, are usually much better biodegradable and show less toxicity than synthetic surfactants. Rhamnolipids are consisted by one or two L-rhamnose molecules as the hydrophilic portion (Monorhamnolipids (Rha-C10? C10) and Dirhamnolipids (Rha-Rha-C10?C10)) and by a fatty acid moiety, saturaded or insaturated, with range between C8 and C12[1] as the hydrophobic portion. Many Rhamnolipids have been established as an effective source against Gram-negative, Gram-positive bacteria, fungi [1] and insects [2]. Pseudomonas sp. LPNMS 012 showed an antifungal activity on antagonism and antibiosis bioassay against Colletotrichum gloeosporioides (Figure A-B). Pseudomonas sp. LPNMS 012 was fermented for five days on PD medium, at 200 rpm and 28 ºC. After that, the culture medium was submitted to solid phase extraction at C18 resin and extracted with methanol. The crude extract generated was analyzed by High Performance Liquid Chromatography coupled with Tandem Mass Spectrometry (Acquity Xevo TQ-S, Waters) in both ESI+ and ESI- modes. The mass spectra (Figure C) displayed an arrangement of peaks appointed to Dirhamnolipid (Figure B) (m/z 673 [M+Na+]+ and m/z 649 [M-H+]-). The chromatogram also displayed a pattern of separation of Monorhamnolipids (527 m/z) and Dirhamnolipid (673 m/z) in ESI+ mode (Figure D)
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