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341.
342.
Advanced oxidation technologies such as ozonation have been proposed to improve removal efficiency of micropollutants during wastewater treatment. In a meta-analysis of peer-reviewed literature, we found no ecotoxicological effects of wastewater ozonation on invertebrates (n = 82), but significant adverse effects on bacteria (n = 24) and fish (n = 5). As information on functional endpoints or trophic interactions is lacking, we applied a bioassay relating to leaf litter decomposition to fill this gap. Leaf discs exposed to ozone-treated wastewater with a high (1.04 mg O3 (mg DOC)−1, n = 49) ozone concentration were significantly preferred by an aquatic detritivore, Gammarus fossarum, over discs conditioned in wastewater not treated with ozone. This effect might have been mediated by reduced bacterial and elevated fungal biomass, and appears to be the first demonstration of wastewater ozonation impacts on invertebrates and an associated ecosystem process. In accordance with the food-choice trials, chemical analyses revealed significantly decreased concentrations of organic micropollutants in wastewater treated with ozone at high concentrations. Thus, food-choice trials as applied here hold promise to assess environmental effects of advanced oxidation technologies in wastewater treatment and appear to be a valuable complement to the ecotoxicological toolbox in general. 相似文献
343.
Kobayashi J Kinoshita K Mizukawa K Sakurai T Imaizumi Y Takada H Suzuki N 《Chemosphere》2011,82(5):745-750
To evaluate the dietary uptake of polychlorinated biphenyls (PCBs) from live food, we investigated the dietary uptake and depuration kinetics of PCBs in a marine benthic fish (marbled sole, Pseudopleuronectes yokohamae) by using as food live sandworms (Perinereis nuntia) that were laboratory-exposed to field-collected PCB-contaminated sediment. Marbled sole were fed the PCB-contaminated sandworms for 28 d and then uncontaminated sandworms for 56 d. The assimilation efficiencies (AEs) of 84 PCB congeners via the gastrointestinal tract (GIT) to the muscle of the fish ranged from 0.21 to 0.78; whole-body AEs would be lower than those of muscle because of the lower PCB concentrations, on a lipid basis. The AEs determined in this study were lower than those in other studies that used PCB-spiked commercial pelletized food. The lower AEs found in this study might be attributable to differences in the food administered (live sandworms vs. commercial pellet food), possibly because of low digestibility of sandworm lipids by marbled sole. In addition, the AEs in this study tended to increase with increasing log octanol-water partition coefficients (KOW) up to about seven, although AEs in the other studies using commercial pelletized food did not increase with increasing log KOW. This result suggests the co-transport of highly hydrophobic PCB congeners along with lipids and fatty acids from the digested sandworms into the GIT epithelium cells. The growth-corrected half-lives of 26 PCB congeners in the muscle of fish ranged from 20 to 107 d. 相似文献
344.
The key stocks and flows of phosphorus (P) through food consumption in Beijing and Tianjin, two megacities in northern China, were explored using a material flow analysis (MFA) approach to construct a static model of P metabolism. A total of 4498 t P has accumulated with 72% of P flow imported through food consumption eventually remaining in Beijing in 2008. Around 64% of the total inflow of P (2670 t) remained in Tianjin in 2008. P in the uncollected sewage from both urban and rural residents and the effluents from sewage treatment plants has significant negative effects on water quality. An average of 55% the P flow remained in the sewage sludge through urban food consumption. The key problems in P metabolism and management in megacities are identified based on the quantitative analysis of P cycling through food consumption. Relevant solutions for improving P recycling efficiency are also discussed. It is important to link P flows with environmental regulations and to establish a strong coordination between urban and rural areas for nutrient recycling to attain sustainable development of megacities. 相似文献
345.
Harvests of crops, their trade and consumption, soil erosion, fertilization and recycling of organic waste generate fluxes of phosphorus in and out of the soil that continuously change the worldwide spatial distribution of total phosphorus in arable soils. Furthermore, due to variability in the properties of the virgin soils and the different histories of agricultural practices, on a planetary scale, the distribution of total soil phosphorus is very heterogeneous. There are two key relationships that determine how this distribution and its change over time affect crop yields. One is the relationship between total soil phosphorus and bioavailable soil phosphorus and the second is the relationship between bioavailable soil phosphorus and yields. Both of these depend on environmental variables such as soil properties and climate. We propose a model in which these relationships are described probabilistically and integrated with the dynamic feedbacks of P cycling in the human ecosystem. The model we propose is a first step towards evaluating the large-scale effects of different nutrient management scenarios. One application of particular interest is to evaluate the vulnerability of different regions to an increased scarcity in P mineral fertilizers. Another is to evaluate different regions’ deficiency in total soil phosphorus compared with the level at which they could sustain their maximum potential yield without external mineral inputs of phosphorus but solely by recycling organic matter to close the nutrient cycle. 相似文献
346.
二次指数平滑法的成都市餐厨垃圾产量预测 总被引:4,自引:0,他引:4
餐厨垃圾的产生量直接影响其处理规模,指数平滑法是对于缺乏基础数据的模型预测的一种有效方法。本文以2001~2009年成都市餐厨垃圾产量数据为基础,运用二次指数平滑预测法对成都市餐厨垃圾产量进行预测,预测结果显示2010年成都市餐厨垃圾产量将达到514.96 t/d。 相似文献
347.
The radiological status of the Greek marine environment, prior to the Chernobyl accident, was characterized mainly by the fallout from nuclear weapon tests. However, the release of radioactivity into the environment from the accident in the Chernobyl Nuclear Power Plant and its deposition in the Greek marine environment resulted in an increase of the 137Cs activity concentration by approximately one order of magnitude. In addition, the direct transport of radiocaesium into the North Aegean Sea has been further influenced by the late impact of the Chernobyl accident on the Greek marine environment, related to the transfer of 137Cs, mainly through the Dnieper but also the Danube rivers, to the Black Sea and further to the North Aegean Sea through the Straits of Dardanelles. The aim of this work is to provide a present day picture of the geographic variation of the concentration of 137Cs in the surface layer of the Greek marine environment and hence, to evaluate the annual committed effective dose delivered to humans through the ingestion pathway from marine sources. 相似文献
348.
The environmental assessment of long-term nuclear waste management requires data to estimate food chain transfers for radionuclides in various environmental settings. For key elements such as iodine (I) and chlorine (Cl), there is a paucity of transfer factor data, particularly outside of agricultural food chains. This study dealt with transfers of I, Cl and 28 other elements to foods that would be typical of boreal hunter/gatherer lifestyles, as well as being common foods for modern recreational and subsistence hunters. Food/substrate concentration ratios (CRs) and related transfer factors for eight species of widely distributed fish, whitetail deer (Odocoileus virginianus), Canada geese (Branta canadensis) and wild blueberries (Vaccinium myrtilloides) were measured and compared to the literature. Limited data were obtained for caribou (Rangifer tarandus), elk (Cervus elaphus) and moose (Alces americanus). Freshwater sediment Kd values and CRs for a ubiquitous freshwater macrophyte were also obtained. The CRs for I in fish were 29 L kg−1 in edible muscle (fillets) of large-bodied species and 85 L kg−1 for whole, small-bodied fish. The log CRs for fish and macrophytes were correlated across elements. For several elements, the Kds for sediments in deep water were ∼4-fold higher than for littoral samples. The elemental transfers to wild animals for some elements were notably different than the literature indicates for domestic animals. It is argued that the transfer data obtained using indigenous elements from real environmental settings, as opposed to contaminant elements in experimental or impacted environments, are especially relevant to assessment of long-term impacts. 相似文献
349.
Sven Kullander 《Ambio》2010,39(3):249-256
Humankind is currently faced with the huge challenge of securing a sustainable energy supply and biofuels constitute one of
the major options. However, the commercially traded edible crops are barely sufficient to meet food demand of the present
world population. Certain regions, for example EU-27, do not even have a sufficient indigenous crop production. Of this follows
that motor biofuels based on edible crops should be avoided. To replace more than some percent of the fossil motor fuels,
non-edible biomass—rest products and wastes—should instead be considered for conversion to biofuels. In this way, about 10%
of the current fossil fuels can be replaced. Feeding a world population expected to grow by some 50% during the next 50 years
will be a major challenge. For environmental reasons it seems that agricultural land cannot be expanded very much, maybe not
at all. The solution to the increasing food demand seems therefore to be using the present crop production more efficiently
and increasing output from present agricultural land, maintaining biodiversity and climate stability within reasonable limits.
In the future, agriculture will need more energy and more water irrigation. Food production is, however, already very energy
demanding, requiring several times more externally provided energy than the energy content of the food itself. A sufficient
energy supply will be a key issue for the future farming! 相似文献
350.
A database of global agricultural primary production has been constructed and used to estimate its energy content. The portion
of crops available for food and biofuel after postharvest losses was evaluated. The basic conditions for agriculture and plant
growth were studied, to ensure sustainable scenarios regarding use of residues. The available energy contents for the world
and EU27 was found to be 7,200–9,300 and 430 TWh, respectively, to be compared with food requirements of 7,100 and 530 TWh.
Clearly, very little, or nothing, remains for biofuel from agricultural primary crops. However, by using residues and bioorganic
waste, it was found that biofuel production could theoretically replace one-fourth of the global consumption of fossil fuels
for transport. The expansion potential for global agriculture is limited by availability of land, water, and energy. A future
decrease in supply of fossil energy and ongoing land degradation will thus cause difficulties for increased biofuel production
from agriculture. 相似文献