GOAL, SCOPE AND BACKGROUND: Over the last decade Greece has become a leading country in the EU as concerns the cage farming of seabream and seabass. A strong debate has risen, however, about the environmental impacts of aquacultures in the coastal areas. The present paper deals with this problem and it is based on measurements of physico-chemical parameters in the water column, particulate matter and sediments in the area of Astakos Gulf, a coastal embayment in western Greece where three big fish farms are currently operating. METHODS: Water samples were collected by using Hydro-Bios sampling bottles, whereas a prototype sediment trap was installed under a fish cage for the collection of particulate matter. Temperature, dissolved oxygen, pH and salinity were measured in situ using portable equipment. Nutrients were determined by standard spectrophotometric methods. Trace metals were determined by Atomic Absorption Spectrometry. Dissolved organic carbon was determined by a Shimadzu 5000A carbon analyzer, whereas organic carbon in sediments was determined titrimetrically. RESULTS AND DISCUSSION: No clear eutrophication incidents have been identified, although the water column near the fish farms was enriched in nutrients and organic carbon. A sludge 'blanket' covers considerable parts of the seabed and is enriched in colloidal organic carbon and trace metals (Cd, Cu, Fe and Zn) that come from unused fish food. The biodegradation of this sludge leads to the development of anoxic conditions followed by the formation of undesirable gases, precipitation or remobilization of metals and the extinction of benthic fauna. CONCLUSION: The operation of fish farms at the coastal area of Astakos Gulf, and probably in similar Mediterranean gulfs, affects the marine environment, particularly in the vicinity of the cages. The most significant influence concerns the near-bottom water layer. The environmental impacts depend on the amount of food given to fishes, the mode of feeding, the fish density in cages, the annual production and the years of unit operation. The hydrology and the geomorphology of the area are also critical factors for its environmental quality. RECOMMENDATION AND OUTLOOK: The success of the fish-farming sector in the Mediterranean is accompanied by environmental and, in some extents, by social and marketing problems. These problems, derived from the rapid development of fish farming, can be solved only through an integrated management, using methods such as environmental impact assessment, risk assessment, economic evaluation, vulnerability assessments, resource accounting, cost-benefit analysis and outcome-based monitoring. 相似文献
EuroBionet, the 'European Network for the Assessment of Air Quality by the Use of Bioindicator Plants', is an EU-funded cooperative project currently consisting of public authorities and scientific institutes from 12 cities in 8 countries. In 2000, the bioindicator plants tobacco (Nicotiana tabacum Bel W3), poplar (Populus nigra 'Brandaris'), spiderwort (Tradescantia sp. clone 4430), Italian rye grass (Lolium multiflorum italicum) and curly kale (Brassica oleracea acephala) were exposed to ambient air at 90 monitoring sites according to standardised methods. Visible injuries and growth parameters were assessed and the accumulation of toxic substances in leaves determined. The exposure of tobacco resulted in a gradient with low levels of ozone-induced foliar injury in N and NW Europe, and medium to high values in the southern and central regions. The results of heavy metal and sulphur analyses in rye grass samples generally showed low to very low sulphur and low to medium heavy metal concentrations in leaves. In some cities, however, local hot spots of heavy metal contamination were detected. Analyses of the PAH contents in curly kale leaves gave low to medium values, with locally elevated levels at traffic-exposed sites. 相似文献
Objective: The lower extremity of the occupant represents the most frequently injured body region in motor vehicle crashes. Knee airbags (KABs) have been implemented as a potential countermeasure to reduce lower extremity injuries. Despite the increasing prevalence of KABs in vehicles, the biomechanical interaction of the human lower extremity with the KAB has not been well characterized. This study uses computational models of the human body and KABs to explore how KAB design may influence the impact response of the occupant's lower extremities.
Methods: The analysis was conducted using a 50th percentile male occupant human body model with deployed KABs in a simplified vehicle interior. The 2 common KAB design types, bottom-deploy KAB (BKAB) and rear-deploy KAB (RKAB), were both included. A state-of-the-art airbag modeling technique, the corpuscular particle method, was adopted to represent the deployment dynamics of the unfolding airbags. Validation of the environment model was performed based on previously reported test results. The kinematic responses of the occupant lower extremities were compared under both KAB designs, 2 seating configurations (in-position and out-of-position), and 3 loading conditions (static, frontal, and oblique impacts). A linear statistical model was used to assess factor significance considering the impact responses of the occupant lower extremities.
Results: The presence of a KAB had a significant influence on the lower extremity kinematics compared to no KAB (P <.05) by providing early restraint and distributing contact force on the legs during airbag deployment. For in-position occupants, the KAB generally tended to decrease tibia loadings. The RKAB led to greater lateral motion of the legs compared to the BKAB, resulting in higher lateral displacement at the knee joint and abduction angle change (51.2 ± 21.7 mm and 15° ± 6.0°) over the dynamic loading conditions. Change in the seating position led to a significant difference in occupant kinematic and kinetic parameters (P <.05). For the out-of-position (forward-seated) occupant, the earlier contact between the lower extremity and the deploying KAB resulted in 28.4° ± 5.8° greater abduction, regardless of crash scenarios. Both KAB types reduced the axial force in the femur relative to no KAB. Overall, the out-of-position occupant sustained a raised axial force and bending moment of the tibia by 0.8 ± 0.2 kN and 21.1 ± 8.7 Nm regardless of restraint use.
Conclusions: The current study provided a preliminary computational examination on KAB designs based on a limited set of configurations in an idealized vehicle interior. Results suggested that the BKAB tended to provide more coverage and less leg abduction compared to the RKAB in oblique impact and/or the selected out-of-position scenario. An out-of-position occupant was associated with larger abduction and lower extremity loads over all occupant configurations. Further investigations are recommended to obtain a full understanding of the KAB performance in a more realistic vehicle environment. 相似文献
Two biological aerated filters (BAF) were setup for ammonia removal treatment of the circulation water in a marine aquaculture. One
of the BAFs was bioaugmented with a heterotrophic nitrifying bacterium, Lutimonas sp. H10, where the ammonia removal was not
improved and the massive inoculation was even followed by a nitrification breakdown from day 9 to 18. The nitrification was remained
stable in control BAF operated under the same conditions. Fluorescent in situ hybridization (FISH) with rRNA-targeted probes and
cultivable method revealed that Lutimonas sp. H10 almost disappeared from the bioaugomented BAF within 3 d, and this was mainly
due to the infection of a specific phage as revealed by flask experiment, plaque assay and transmission electron observation. Analyses
of 16S rRNA gene libraries showed that bacterial groups from two reactors evolved di erently and an overgrowth of protozoa was
observed in the bioaugmented BAF. Therefore, phage infection and poor biofilm forming ability of the inoculated strain are the main
reasons for bioaugmentation failure. In addition, grazing by protozoa of the bacteria might be the reason for the nitrification breakdown
in bioaugmented BAF during day 9–18. 相似文献