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311.
Characteristic levels of metal ions in post dredged sediment and dredged sediments materials of a municipal creek in the Niger
Delta show that significant concentrations of heavy metals are found to be accumulated more on the surface (0–15cm depth)
of the dredged material as compared to the sub surface (15–30cm) and post dredged sediments. The distribution patterns were
in the following order Fe > Mn > Zn > Cu > Pb > Ni > Cd and Fe > Mn > Zn > Pb > Cu > Ni > Cd for the post dredged sediment
and dredged sediment materials respectively. The levels of the various metals were far below the EPA screening levels for
open water disposal, consequently total levels of heavy metal found in these sediments pose no problem by open-water or upland
disposal 相似文献
312.
313.
Pollution in the marine protected area of North Sporades Islands was investigated in July 1997. Salinity, temperature, dissolved oxygen, dissolved inorganic nutrients, organic carbon, hydrocarbons as well as dissolved and particulate trace metals were determined at 15 offshore and coastal stations. Dissolved organic carbon and inorganic nutrient concentrations indicate the mesotrophic character of the investigated waters. The dissolved forms of nitrogen were slightly higher at coastal stations. Dissolved and particulate Cu, Zn and Ni, were higher in coastal stations, whereas concentrations of Pb were generally low and likely of atmospheric origin. Dissolved/Dispersed petroleum hydrocarbons (DDPH) were close to detection limits at all stations. Temperature and salinity vertical profiles, nutrient and trace metal concentrations revealed the presence of a slight influence of the Black Sea water coming from Dardanelles straits. 相似文献
314.
Ryo?ShojiEmail author Takanori?Miyazaki Takashi?Niinou Mikio?Kato Hiroshi?Ishii 《Journal of Material Cycles and Waste Management》2004,6(2):142-146
We have successfully prepared a bead-type adsorbent from two materials with different adsorption characteristics. Heavy metals were removed by greatly swollen egg shell membrane-conjugated chitosan beads. The egg shell membrane accumulated and removed precious metal ions from a dilute aqueous solution with a high affinity in a short contact time. Experiments suggested that chitosan beads could take up gold ions with great capacity and selectivity by conjugation with egg shell membrane. Under certain conditions, the selective removal of gold and copper in a mixture of gold and copper ions by egg shell membrane-conjugated chitosan beads was 100% and 2%, respectively. Egg shell membrane-conjugated chitosan beads can be seen as a promising material to recover gold in wastewater from various industries, such as electroplating. 相似文献
315.
Monitoring environmental pollution in Erzurum by chemical analysis of Scots pine (Pinus sylvestris L.) needles 总被引:3,自引:0,他引:3
Pollution distribution maps of copper (Cu), zinc (Zn) and lead (Pb) for Erzurum province were developed on the basis of chemical analysis of Scots pine (Pinus sylvestris L.) needles collected from randomly selected sampling points during 2 years. The maps show deposition zones for the studied elements and could help in identification of sources and directions of air pollution dispersion. This study indicated that vegetation in Erzurum was greatly endangered by sulphur dioxide (SO(2)), whereas Zn does not pose an immediate threat to vegetation in most of the country's territory. However, in the city center, main and secondary road agglomeration, very high pollution with Pb and Cu could limit growth. Higher levels of SO(2) measured in some areas of Erzurum might be harmful for human and animal health. Results of this study indicated that Scots pine needles were not contaminated by Zn. 相似文献
316.
Muniz P Danulat E Yannicelli B García-Alonso J Medina G Bícego MC 《Environment international》2004,29(8):1019-1028
As part of the first environmental assessment within Montevideo Harbour, in summer and winter of 1998, sediments samples were collected at eight locations to determine the spatial distribution of anthropogenic pollutants. Muddy sediments with high organic matter content dominate the study area. Heavy metal levels indicated that sediments were highly polluted with Zn (overall mean: 312+/-102 microg g(-1) dry sediment), Pb (85+/-31), Cu (89+/-25), Cr (162+/-62), and Hg (0.63+/-0.3) and moderately with Ni (30+/-2) and Ag (1.2+/-0.4). Depending on location and season, aliphatic hydrocarbons reached from 21 to 120 microg g(-1), while the unresolved complex mixture represented up to 76% of the total aliphatic fraction. Total PAH concentrations ranged from 1.56 to 90.44 microg g(-1); except at one location, petroleum derivatives were identified as main local source. The results pointed out that almost all the harbour area presented some substances that can cause adverse biological effects, especially in the inner region where all metals are above PEL levels. Principal components analysis confirmed that the inner harbour region is most severely affected by the pollutants and it was possible to differentiate three regions according to their environmental quality. 相似文献
317.
Environmental changes in Sepetiba Bay,SE Brazil 总被引:2,自引:0,他引:2
M.?M.?Molisani R.?V.?Marins W.?Machado H.?H.?M.?Paraquetti E.?D.?Bidone L.?D.?LacerdaEmail author 《Regional Environmental Change》2004,4(1):17-27
Sepetiba Bay is an example of an aquatic environment that has been severely impacted by human occupation and industrial activities in its basin. Some 400 industries including metallurgical, petrochemical and pyrometallurgical smelters, which emitted pollutants to air, soil and water, were established in Sepetiba Basin during the past 30 years. Apart from these point sources, changes in land use have also resulted in a large remobilization of pollutant deposition on Sepetiba Bay Basin. Studies have pointed out significant changes in sedimentation rates, concentrations of inorganic pollutants (Zn, Cd, Pb and Hg) and more recently, eutrophication, pointing to this area as an example of an impacted coastal zone. Notwithstanding local sources, Sepetiba Bay also suffers environmental impacts caused by diversion of river waters from adjacent basins, with some 30% of the total Hg flux to Sepetiba Bay and a 10-fold increase in water and sediment fluxes resulting from this. Decreasing environmental quality compromises both the large biodiversity and the potential economic uses of Sepetiba Bay, including fisheries and tourism. Monitoring of heavy metal levels in organisms (algae, mollusks, crustaceans and oysters) often shows concentrations well above the limits allowed following Brazilian legislation for food quality. Historical evolution of these concentrations suggests a worsening of the situation. Failure to monitor the effect of land-based activities, including those from other basins artificially associated with Sepetiba Bay has resulted in poor scenario construction and proper management planning. 相似文献
318.
319.
Heavy metals in fly ash from municipal solid waste incinerators are present in high concentrations. Therefore fly ash must be treated as a hazardous material. On the other hand, it may be a potential source of heavy metals. Zinc, lead, cadmium, and copper can be relatively easily removed during the thermal treatment of fly ash, e.g. in the form of chlorides. In return, wet extraction methods could provide promising results for these elements including chromium and nickel. The aim of this study was to investigate and compare thermal and hydrometallurgical treatment of municipal solid waste fly ash. Thermal treatment of fly ash was performed in a rotary reactor at temperatures between 950 and 1050 °C and in a muffle oven at temperatures from 500 to 1200 °C. The removal more than 90% was reached by easy volatile heavy metals such as cadmium and lead and also by copper, however at higher temperature in the muffle oven. The alkaline (sodium hydroxide) and acid (sulphuric acid) leaching of the fly ash was carried out while the influence of temperature, time, concentration, and liquid/solid ratio were investigated. The combination of alkaline-acidic leaching enhanced the removal of, namely, zinc, chromium and nickel. 相似文献
320.
《Journal of Manufacturing Processes》2014,16(1):86-92
The paper reviews the principles, benefits and limitations of the conventional short circuit transfer mode in GMA welding before describing the development and benefits of the controlled short circuit approach. Various options are described and an attempt is made to categorize the current commercial systems. 相似文献