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51.
Environmental Chemistry Letters - Pollution of waste and natural waters by antibiotics is a major health issue that induces the development of resistant pathogens. Pollutant may be removed by...  相似文献   
52.
Environmental Science and Pollution Research - Selenite and selenate are two main selenium (Se) forms absorbed by plants. The comparative effects of selenite and/or selenate on Se uptake and...  相似文献   
53.
The TiO2/SiO2 composite was prepared by means of the SiO2-particle-entrapment method. The FTIR data showed the presence of Si–O–Ti stretching vibration band at 970 cm−1 in the TiO2/SiO2 composite, suggesting a reaction between TiO2 and silica on the TiO2 particle surface during the silicagel formation around the TiO2 particles. The photocatalytic efficiency of TiO2 immobilized in silicagel was compared with that of the conventional TiO2 Degussa P25 catalyst. For this purpose, the degradation of indigo carmin (IC) dye was used as model molecule in the tests. The effect of operational parameters such as catalyst loading and dye concentration on the photocatalytic degradation of the model dye was investigated. The rate of degradation increased with increasing catalyst loading, and when the concentration of the dye decreases.  相似文献   
54.
If measures to reduce the industrial discharge of PM10 shall be planned with high accuracy, a first step must be to estimate the contribution of single industrial facilities to the overall PM10 burden as accurately as possible. In northern Duisburg as an example, an area where iron and steel producing industry is concentrated, PM10 was measured at 4 sampling sites very close to an industrial complex of blast furnaces, a sinter plant, oxygen steel works and a coke oven plant for 9 months in 2006. At two sites metals in PM10 were determined. The results, together with analytical data of urban background sites in the region and data of wind direction and wind speed were used for an estimation of the contribution of single plants to the PM10 burden. A careful analysis of the data showed, that the data of PM10, calcium, iron and zinc measured at two sites close to the industrial area and information about the urban background aerosol were sufficient to calculate the PM10 contribution of the main single plants. The data could be compared with those of modelling.  相似文献   
55.
Animal wastewater lagoons nearby concentrated animal feeding operations (CAFOs) represent the latest tendency in global animal farming, severely impacting the magnitude of greenhouse gas emissions, including nitrous oxide (N2O). We hypothesized that lagoon wastewater could be supersaturated with N2O as part of incomplete microbial nitrification/denitrification processes, thereby regulating the N2O partitioning in the gaseous phase. The objectives of this study were: (i) to investigate the magnitude of dissolved N2O concentrations in the lagoon; and (ii) to determine the extent to which supersaturation of N2O occurs in wastewater lagoons. Dissolved N2O concentrations in the wastewater samples were high, ranging from 0.4 to 40.5 μg N2O mL−1. Calculated dissolved N2O concentrations from the experimentally measured partition coefficients were much greater than those typically expected in aquatic systems (<∼0.6 μg N2O mL−1). Knowledge of the factors controlling the magnitude of N2O supersaturation could potentially bridge mass balance differences between in situ measurements and global N2O models.  相似文献   
56.
Concentrated animal feeding operations around the globe generate large amounts of nitrous oxide (N2O) in the surrounding atmosphere. Liquid animal waste systems have received little attention with respect to N2O emissions. We hypothesized that the solution chemistry of animal waste aqueous suspensions would promote conditions that lead to N2O supersaturation at the liquid/air interface. The concentration of dissolved N2O in poultry litter (PL) aqueous suspensions at 25 °C was 0.36 μg N2O mL−1, at least an order of magnitude greater than that measured in water in equilibrium with ambient air, suggesting N2O supersaturation. There was a nonlinear increase in the N2O Henry constants of PL from 2810 atm/mole fraction at 35 °C to 17 300 atm/mole fraction at 41 °C. The extremely high N2O Henry constants were partially ascribed to N2O complexation with aromatic moieties. Complexed N2O structures were unstable at temperatures > 35 °C, supplying the headspace with additional free N2O concentrations.  相似文献   
57.
The task of adapting cities to the impacts of climate change is of great importance—urban areas are hotspots of high risk given their concentrations of population and infrastructure; their key roles for larger economic, political and social processes; and their inherent instabilities and vulnerabilities. Yet, the discourse on urban climate change adaptation has only recently gained momentum in the political and scientific arena. This paper reviews the recent climate change adaptation strategies of nine selected cities and analyzes them in terms of overall vision and goals, baseline information used, direct and indirect impacts, proposed structural and non-structural measures, and involvement of formal and informal actors. Against this background, adaptation strategies and challenges in two Vietnamese cities are analyzed in detail, namely Ho Chi Minh City and Can Tho. The paper thereby combines a review of formalized city-scale adaptation strategies with an empirical analysis of actual adaptation measures and constraints at household level. By means of this interlinked and comparative analysis approach, the paper explores the achievements, as well as the shortcomings, in current adaptation approaches, and generates core issues and key questions for future initiatives in the four sub-categories of: (1) knowledge, perspectives, uncertainties and key threats; (2) characteristics of concrete adaptation measures and processes; (3) interactions and conflicts between different strategies and measures; (4) limits of adaptation and tipping points. In conclusion, the paper calls for new forms of adaptive urban governance that go beyond the conventional notions of urban (adaptation) planning. The proposed concept underlines the need for a paradigm shift to move from the dominant focus on the adjustment of physical structures towards the improvement of planning tools and governance processes and structures themselves. It addresses in particular the necessity to link different temporal and spatial scales in adaptation strategies, to acknowledge and to mediate between different types of knowledge (expert and local knowledge), and to achieve improved integration of different types of measures, tools and norm systems (in particular between formal and informal approaches).  相似文献   
58.
Biodegradability of a polyacrylate superabsorbent in agricultural soil   总被引:1,自引:0,他引:1  
Superabsorbent polymers (SAP) are used, inter alia, as soil amendment to increase the water holding capacity of soils. Biodegradability of soil conditioners has become a desired key characteristic to protect soil and groundwater resources. The present study characterized the biodegradability of one acrylate based SAP in four agricultural soils and at three temperatures. Mineralisation was measured as the 13CO2 efflux from 13C-labelled SAP in soil incubations. The SAP was either single-labelled in the carboxyl C-atom or triple-labelled including additionally the two C-atoms interlinked in the SAP backbone. The dual labelling allowed estimating the degradation of the polyacrylate main chain. The 13CO2 efflux from samples was measured using an automated system including wavelength-scanned cavity ring-down spectroscopy. Based on single-labelled SAP, the mean degradation after 24 weeks varied between 0.45 % in loamy sand and 0.82 % in loam. However, the differences between degradation rates in different soils were not significant due to a large intra-replicate variability. Similarly, mean degradation did not differ significantly between effective temperature regimes of 20° and 30 °C after 12 weeks. Results from the triple-labelled SAP were lower as compared to their single-labelled variant. Detailed results suggest that the polyacrylate main chain degraded in the soils, if at all, at rates of 0.12–0.24 % per 6 months.  相似文献   
59.
Since cotton today is machine picked, the mere process of ginning creates a significant amount of trash and dust. A large cotton gin in Fresno operating at 23 bales per hour uses two rotating filters to control this material. Total emissions from the facility are in the order of 50 pounds per hour, or about one-half the emissions from a typical gin using cyclones as control equipment.  相似文献   
60.
L. Dagorn  P. Bach  E. Josse 《Marine Biology》2000,136(2):361-371
 The horizontal and vertical movements of large bigeye tuna (Thunnus obesus Lowe, 1839; 25 to 50 kg) captured in the south Pacific Ocean (French Polynesia) were determined using pressure-sensitive ultrasonic transmitters. Bigeye tuna swam within the first 100 m below the surface during the night-time and at depths between 400 and 500 m during the daytime. The fish exhibited clear relationships with the sound scattering layer (SSL). They followed its vertical movements at dawn and dusk, and were probably foraging on the organisms of the SSL. Bigeye tuna did, however, make regular rapid upward vertical excursions into the warm surface layer, most probably in order to regulate body temperature and, perhaps, to compensate for an accumulated oxygen debt (i.e. to metabolize lactate). The characteristics of these dives differ from those reported from previous studies on smaller bigeye tuna (∼12 kg) near the main Hawaiian Islands. During the daytime, the large fish in French Polynesia made upward excursions approximately only every 2.5 h, whereas smaller fish in Hawaiian waters made upward excursions approximately every hour. Our data are the first observations on the role of body size in the vertical behavior of bigeye tuna. Received: 9 September 1998 / Accepted: 25 November 1999  相似文献   
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