Samples of fish were collected by beach seine throughout the shallow waters of the large Peel-Harvey estuarine system (south-western Australia) in the wet (June to November) and dry periods (December to May) between August 1979 and July 1981. The number of species, density and biomass declined with distance from the estuary mouth and rose with increasing temperature and salinity. Both classification and ordination distinguished the faunal composition of the saline reaches of the rivers from that of the narrow Entrance Channel and two large basins (Peel Inlet and Harvey Estuary). Classification also separated the fauna of the riverine group into wet- and dry-period components, and divided samples taken in the Entrance Channel from those in the basins. Differences between the faunal composition of the Peel Inlet and its tributary rivers were related to differences in salinity regime. The riverine fauna was subjected to much more variable and lower minimum salinities. Species characteristic of the rivers included teleosts such as Atherinosoma wallacei and Amniataba caudavittatus, which are estuarine sensu stricto in southwestern Australia, the semi-anadromous Nematalosa vlaminghi and juveniles of the marine Mugil cephalus. The species diagnostic of the wet periods in the rivers were the estuarine species A. wallacei and Favonigobius suppositus, while the dry periods were characterised by the marine species Atherinomorus ogilbyi and Sillago schomburgkii. Marine species also characterised the Entrance Channel (Favonigobius lateralis, Sillago bassensis), whereas the indicators in Peel Inlet and Harvey Estuary were Hyporhamphus regularis and Apogon rueppellii, both of which can pass through the whole of their life cycle in estuarine as well as marine environments. 相似文献
The Fusaro Lagoon is a shallow lagoon, located in SW Italy, largely influenced in the last decades by several anthropic impacts. The study examined the pollution status of the lagoon, during year 2011–2012 at nine sampling stations with the aim to find out proper measurements of water lagoon restoration. Concentrations of heavy metals (HMs) (aluminium [Al], barium [Ba], cadmium [Cd], copper [Cu], iron [Fe], manganese [Mn], vanadium [V] and zinc [Zn]) were examined in water, sediments and specimens of the ascidian Ciona intestinalis sp. A. Low levels of dissolved oxygen concentration were detected at many stations, with mean values of 5.2–6.4 mg L?1. The redox potential of surface waters was also low, ?2.7 to 50.7 mV. Sediments possessed high organic matter content, 17.7–29.4 %. In sediments, the mean Zn level, 251.4 mg kg?1, was about sixfold higher than that recorded in year 2000 (38.5 mg kg?1) and considerably higher than that recorded in 2007 (191 mg kg?1). The mean levels of Cd were outstandingly high, with a mean value of 70.5 mg kg?1, about 30- and 50-fold higher than those determined in 2000 and 2007, respectively. Cadmium (Cd), Cu and nickel (Ni) appeared in excess with respect to most current guidelines, reaching significant pollution levels. C. intestinalis sp. A was detected only at few stations, with metals accumulated preferentially in the body in respect to the tunic, from 1.2 times for Zn (178 mg kg?1) to 4.0 times for V (304 mg kg?1). Data suggests the necessity of an immediate action of eco-compatible interventions for environmental restoration. 相似文献
Twenty eight short sediment cores, collected along six transects in two areas influenced by the frontal system formed by the Po River, were analysed for Th and Cs in order to improve our knowledge on short time scale sediment deposition, accumulation and mixing. Sedimentological and mineralogical parameters were also analysed._ The decreasing Cs activities and C/N values in surface sediments indicate a decreasing input of terrestrial material during the study period. Furthermore, low excess thorium activities and inventories at some sites, together with low sedimentary organic matter concentrations in the southern area, suggest that the productivity in summer 1997 was lower than in 1996. Temporal and spatial shifts of the front exert a strong influence on short time scale deposition of particulate matter in the northern area, while the front position is more stable in the southern area, influencing both seasonal and interannual deposition._ The comparison between apparent seasonal and pluri-annual accumulation rates suggests, for the northern area, a sedimentation pattern characterized by temporal deposition of material on to the sea floor, with periodical resuspension. The net apparent accumulation is 0.1-0.4 r g r cm r yr. The same occurs for the southern area, where values are higher, probably due to the longer persistence of the frontal system in the same area over the years. Here, both seasonal and pluri-annual deposition showed the same pattern, but seasonal values were two to three times higher with a net apparent accumulation rate of 0.3-0.8 r g r cm r yr. Organic carbon and nitrogen concentrations are generally less than 1.3 and 0.2% d.w., with lower values in the southern area. By contrast, mass fluxes showed higher values in the southern area, while the rate of removal over a pluri-annual time scale is generally high. 相似文献
Supported Fe2O3/WO3 nanocomposites were fabricated by an original vapor phase approach, involving the chemical vapor deposition (CVD) of Fe2O3 on Ti sheets and the subsequent radio frequency (RF)-sputtering of WO3. Particular attention was dedicated to the control of the W/Fe ratio, in order to tailor the composition of the resulting materials. The target systems were analyzed by the joint use of complementary techniques, that is, X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDXS), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and optical absorption spectroscopy. The results showed the uniform decoration of α-Fe2O3 (hematite) globular particles by tiny WO3 aggregates, whose content could be controlled by modulations of the sole sputtering time. The photocatalytic degradation of phenol in the liquid phase was selected as a test reaction for a preliminary investigation of the system behavior in wastewater treatment applications. The system activity under both UV and Vis light illumination may open doors for further material optimization in view of real-world end-uses.
- DOI: http://dx.doi.org/10.1065/espr2006.01.014
Background, Aims and Scope Triazole-derivatives are potent antifungal agents used as systemic agricultural fungicides and against fungal diseases in
humans and domestic animals. They act by inhibiting the cytochrome P-450 conversion of lanosterol to ergosterol, thus resulting
in faulty fungal cell wall synthesis. Some data have been published about the teratogenic activity of triazoles on rodent
embryos: Hypoplasias, abnormal shape, agenesis of the branchial arches, for example, were reported as typical induced malformations.
Unfortunately, no data are available on the embryotoxicity of these compounds in amphibians, despite the increasing concern
among the scientific community about the phenomenon of global amphibian population declines. The aim of the present work is
to evaluate the embryo-lethal and teratogenic potentials of Triadimefon (FON), a triazolederivative widely used as an antimycotic
in agriculture, by the test FETAX (Frog Embryos Teratogenic Assay, Xenopus) with particular attention being paid to the analysis
of branchial arch malformations.
Methods Xenopus laevis embryos were exposed continuously from stage 9 to increasing concentrations of FON and analyzed at stage 47
for mortality and teratogenicity (group I) to determine the median lethal (LC50) and teratogenic (TC50) concentrations. Another
two pools of larvae were exposed to FON for a 2 hour period at early gastrula (Group II) or neurula (Group III) stages to
verify which period of development is the most sensitive to FON. The malformations observed were further investigated by histological
section and cartilage staining with Alcian blue.
Results and Discussion The assay has estimated LC50 and TC50 values of 63.8 μM and 2.73 μM, respectively; the resulting TI (Teratogenic Index =
LC50/TC50) value of 23.4 has underlined the very high teratogenic risk associated with this compound. Neurulation was more
sensitive to FON exposure than gastrulation, since the TC50 estimated values for group III (neurula exposed) specimens was
7.6 times lower than those of group II (gastrula exposed). Interestingly, for each group analyzed, 100% of malformed embryos
showed alterations at branchial arch derived cartilages: Anterior cartilages were reduced, missing, fused or incorrectly positioned
while gill cartilages were altered only in the most severely affected specimens. In some cases these malformations were associated
with hyperpigmentation. Our results support the hypothesis that FON can interfere with Neural Crest Cell (NCC) migration,
since craniofacial components and melanophores are derived from neural crest material.
Conclusion In conclusion, our data show Triadimefon to be a potent teratogen able to induce specific craniofacial malformation in Xenopus
laevis embryos, probably interfering with the NCC migration into the branchial mesenchyme. These results are also interesting
for ecotoxicological reasons as FON, as well as other pesticides, are likely to be present in water systems near agricultural
or urban areas which may serve as habitats for developing amphibians and fishes.
Recommendation and Outlook Our results are in agreement with the data obtained on in vitro cultured rat embryos suggesting that the FON mechanism of
action involves strongly conserved molecules. The choice of Xenopus laevis as the model organism allows us to extend the toxicological
and teratological observations to a molecular level, in order to search for novel genes regulated by FON exposure. 相似文献