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381.
The Ria Formosa lagoon, Portugal, receives organic matter from many natural and anthropogenic sources. This paper presents an overview of the contribution these sources made through the use of lipid biomarkers. Sixty-one surface sediment samples were collected and analysed for a range of lipids. Sewage materials were confined to regions within 2 km of discharge points; phytoplankton biomarkers (sterols and fatty acids) suggest production was greatest in the inner parts of the lagoon that also have greatest inorganic nutrient enrichment; terrestrial organic matter was present in relatively low concentrations as shown by both sterol and fatty alcohols; bacteria were widespread although the Sulphate Reducing Bacteria (SRBs, shown by the presence of 3-OH fatty acids) were located near but not adjacent to sewage discharge points. 相似文献
382.
The use of colloid-enhanced ultrafiltration for boron removal from water is investigated. Biodegradable surfactant, 1,4-sorbitol
oleate, was applied to obtain micelles and high molecular weight chitosan to reinforce their stability. Two kind of membranes
were compared: neat porous polysulfone membrane and charged porous sulfonated polysylfone membrane; both with similar average
pore diameter of 5 nm. The studies revealed that two key factors affect the boron rejection: presence of surfactant in the
colloidal mixture and a repulsion effect of sulfone groups on the membrane surface. Both have a positive effect on boron
removal. 相似文献
383.
Efforts are accelerating to protect and restore ecosystems globally. With trillions of dollars in ecosystem services at stake, no clear framework exists for developing or prioritizing approaches to restore coral reefs even as efforts and investment opportunities to do so grow worldwide. Restoration may buy time for climate change mitigation, but it lacks rigorous guidance to meet objectives of scalability and effectiveness. Lessons from restoration of terrestrial ecosystems can and should be rapidly adopted for coral reef restoration. We propose how the 10 golden rules of effective forest restoration can be translated to accelerate efforts to restore coral reefs based on established principles of resilience, management, and local stewardship. We summarize steps to undertake reef restoration as a management strategy in the context of the diverse ecosystem service values that coral reefs provide. Outlining a clear blueprint is timely as more stakeholders seek to undertake restoration as the UN Decade on Ecosystem Restoration begins. 相似文献
384.
Modeling porosity reductions caused by mineral fouling in continuous-wall permeable reactive barriers 总被引:1,自引:0,他引:1
A study was conducted to assess key factors to include when modeling porosity reductions caused by mineral fouling in permeable reactive barriers (PRBs) containing granular zero valent iron. The public domain codes MODFLOW and RT3D were used and a geochemical algorithm was developed for RT3D to simulate geochemical reactions occurring in PRBs. Results of simulations conducted with the model show that the largest porosity reductions occur between the entrance and mid-plane of the PRB as a result of precipitation of carbonate minerals and that smaller porosity reductions occur between the mid-plane and exit face due to precipitation of ferrous hydroxide. These findings are consistent with field and laboratory observations, as well as modeling predictions made by others. Parametric studies were conducted to identify the most important variables to include in a model evaluating porosity reduction. These studies showed that three minerals (CaCO3, FeCO3, and Fe(OH)2 (am)) account for more than 99% of the porosity reductions that were predicted. The porosity reduction is sensitive to influent concentrations of HCO3-, Ca2+, CO3(2-), and dissolved oxygen, the anaerobic iron corrosion rate, and the rates of CaCO3 and FeCO3 formation. The predictions also show that porosity reductions in PRBs can be spatially variable and mineral forming ions penetrate deeper into the PRB as a result of flow heterogeneities, which reflects the balance between the rate of mass transport and geochemical reaction rates. Level of aquifer heterogeneity and the contrast in hydraulic conductivity between the aquifer and PRB are the most important hydraulic variables affecting porosity reduction. Spatial continuity of aquifer hydraulic conductivity is less significant. 相似文献
385.
Jones JM 《Environmental pollution (Barking, Essex : 1987)》1987,48(2):131-144
Measurement of operationally defined chemical fractions in ombrotrophic peat samples provides information not obtained by total metal extractions. Examination of such sequential data permits interpretation of process dynamics. Results for copper, lead and zinc chemical fractionation of peat profiles from Ringinglow Bog, near Sheffield, Great Britain, are reported and discussed. Lead and zinc share similar patterns of partitioning. A considerable proportion of these records is in a form predisposed to transformation and mobilisation. In contrast, much of the copper is comparatively immobile, it being associated with the more chemically intractable fractions. The results suggest that peat copper deposition records may be used for reconstruction of pollution history. The use of lead and zinc records for these purposes is problematic. 相似文献
386.
Saiki MK 《Environmental pollution (Barking, Essex : 1987)》1987,47(3):171-186
Analysis of mosquitofish, Gambusia affinis, has proven useful for monitoring contaminant levels in aquatic biota; however, the small size of this species often requires the compositing of several fish to provide sufficient biomass for selenium analysis. Such composites have usually been obtained without considering the length and sex of the individual fish. The present study found significant differences in mean lengths and sex ratios of mosquitofish sampled with small-mesh dip nets from five sites close to each other in the San Joaquin Valley, California. To test the effect of these different sample characteristics, fish from each site were divided by sex into five size classes (<20, 20-30, 31-45, 46-60, and >60mm total length) before analysis for total selenium. Altogether, fish from the San Luis Drain and Kesterson Ponds 2 and 7 contained 65-360 microg g(-1) selenium (dry weight basis), or about 28- to 300-fold more than concentrations in fish of the same length and sex from the Volta Wasteway and Volta Pond 26. Except for females 31-45 mm long from the San Luis Drain that had higher concentrations than either smaller or larger females, selenium concentrations did not differ significantly among size classes. Although concentrations differed between sexes in samples from the San Luis Drain, Kesterson Pond 2, and Volta Pond 26, neither males nor females consistently had the higher concentrations. In the San Luis Drain, 20-30 and 31-45 mm long females had higher concentrations than did males of the same size classes; in Kesterson Pond 2 and Volta Pond 26, however, 20-30 mm long males had higher concentrations than did females of the same size class. Although no consistent patterns were observed, the occasional differences in selenium concentrations in fish of different length and sex indicate that these variables should be considered when surveys and monitoring studies are designed. 相似文献
387.
Vivian CM 《Environmental pollution (Barking, Essex : 1987)》1987,46(2):105-118
Sediments from the Burbo Bight, Liverpool Bay, were analysed for their total carbohydrate (TCH) and organic carbon (TOC) contents, and the TCH:TOC ratio (when the TCH is expressed as a percentage of the TOC) was used to give an indication of the amount of sewage-derived organic matter in the sediments. The %TCH values found ranged from 17-68 with an average of 40, indicating that sewage-derived organic matter constituted a significant fraction of the organic matter in the sediment. This appears likely to have been derived mainly from the Mersey Estuary outflow and the sewage sludge dumped in Liverpool Bay, but these two sources cannot be distinguished using this technique. It is suggested that further studies are required on the carbohydrates in sewage sludge and coastal sediments to satisfactorily establish this technique. 相似文献
388.
Heavy metal concentrations in the liver of three duck species: influence of species and sex 总被引:1,自引:0,他引:1
To investigate interspecific and intersex differences in heavy metal levels, we analysed concentrations of cadmium, cobalt, chromium, copper, lead, mercury, manganese, nickel and zinc in the livers of male and female black duck (Anas rubripes), mallard (A. platyrhynchos) and greater scaup (Aythya marila) collected in Raritan Bay, New Jersey in December 1980 and January 1981. Certain metal levels varied significantly by species and sex. In all species, Zn and Cu had the highest concentrations, and Cd, Co, and Hg were lowest in all three species. Scaup had significantly higher levels of Cu than black ducks and mallards, and mallards had significantly higher levels of Mn and Zn than black duck and scaup. Overall, eight of nine metal levels were higher in male than female black duck. In scaup, females had significantly higher levels of Pb and Mn than males. In black ducks, males had significantly higher levels of Cu, Mn and Zn than females. The sample of mallard was too small to test intersex differences. 相似文献
389.
Zinc adsorption equilibria were measured in soils differing in pH but with similar textures and total zinc concentrations, using adsorption isotherm and isotopic exchange techniques. The results suggested that the equilibrium between solution and exchangeable zinc was strongly pH dependent and the active zinc species in adsorption was single charged (e.g. Zn(OH)(+)). The size of the exchangeable zinc pool was not strongly pH dependent. Similar results were obtained when zinc was added to the soils, either as Zn(NO(3))(2) or in sewage sludge. 相似文献
390.
Sawidis T Breuste J Mitrovic M Pavlovic P Tsigaridas K 《Environmental pollution (Barking, Essex : 1987)》2011,159(12):3560-3570
Concentrations of four heavy metals were determined in tree leaves and bark collected from polluted and non-polluted areas of three European cities (Salzburg, Belgrade and Thessaloniki) for a comparative study. Platanus orientalis L. and Pinus nigra Arn., widespread in urban northern and southern Europe, were tested for their suitability for air quality biomonitoring. Leaves and barks were collected uniformly of an initial quantity of about 30 g of each sample. Analysis was accomplished by electrothermal atomic absorption spectrometry after total digestion. Site-dependent variations were found with the highest concentration level measured in Belgrade, followed by Thessaloniki and Salzburg. A higher accumulation of heavy metals was found in bark compared to leaves. Pine tree bark, accumulating higher concentrations of trace metals compared to plane tree bark, shows a higher efficiency as bioindicator for urban pollution. Both indicator species are suitable for comparative studies on bioindication of urban air pollution. 相似文献