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291.
Claudia J. K. Engelmann Andy D. Ward Ann D. Christy E. Scott Bair 《Journal of the American Water Resources Association》2002,38(1):289-300
ABSTRACT: The purpose of this study was to evaluate the Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) watershed management system. BASINS data were used with the NPSM model to predict discharge and sediment concentrations at the outlet of a 103 km2 Ohio watershed. It was concluded that the NPSM model should always be calibrated but only a few of the parameters provided with BASINS needed to be calibrated. For a three‐year study period, there was a 2 percent underestimation of discharge using area weighted precipitation values and a 25 percent overestimation using the single station data in BASINS. A comparison of observed and predicted monthly discharge resulted in an r2 of 0.86 with area‐weighted precipitation and an r2 of 0.74 with the single station data. Calibrating the model to substantially improve sediment predictions was unsuccessful and we concluded that a calibration period of one year was too short. For the three‐year study period, the r2 for sediment was 0.36 with a slope of 0.37 and an intercept of 18.8 mg/l. The mean observed and predicted sediment concentrations were 27.1 mg/l and 22.6 mg/l, respectively. 相似文献
292.
Cerda IA Paulina Carabajal A Salgado L Coria RA Reguero MA Tambussi CP Moly JJ 《Die Naturwissenschaften》2012,99(1):83-87
Sauropoda is one of the most diverse and geographically widespread clades of herbivorous dinosaurs, and until now, their remains
have now been recovered from all continental landmasses except Antarctica. We report the first record of a sauropod dinosaur
from Antarctica, represented by an incomplete caudal vertebra from the Late Cretaceous of James Ross Island. The size and
morphology of the specimen allows its identification as a lithostrotian titanosaur. Our finding indicates that advanced titanosaurs
achieved a global distribution at least by the Late Cretaceous. 相似文献
293.
Dirk Gericke Jiri Nekovar Claudia Hörold 《Journal of environmental science and health. Part. B》2013,48(7):639-647
According to the EU directive 91/414/EEC potential environmental concentrations of pesticides have to be assessed with environmental fate models. For the calculation of pesticide concentrations it is necessary to provide an application date which has to match the specific Biologische Bundesanstalt, Bundesamt, Chemische Industrie (BBCH) stage at which the pesticide shall be applied. If these application dates are not available for a specific stage, crop and country they must be estimated, which adds an additional uncertainty to the predicted concentrations. In the present study, we therefore evaluate to which extent application dates can be derived from phenological data. For this analysis phenological data, converted to BBCH stages, of two field crops provided by the German Weather Service (DWD) were analyzed. We found a linear correlation between BBCH stages and the respective appearance dates, which can be used for interpolation of appearance dates of specific BBCH stages. Remarkably, when comparing BBCH stages from Germany and the Czech Republic almost identical correlations of appearance dates and BBCH stages were found. In the next step, soil and climate data from Joint Research Centre (JRC) were analyzed together with phenological data in order to evaluate if BBCH stages can be estimated for countries with other climate or soil conditions. This analysis revealed that temperature, global radiation and evaporation were the parameters with the strongest impact. These parameters were used for estimating appearance dates of BBCH stages for other countries. Exemplarily, appearance dates for maize BBCH were calculated for Italy. Estimated and observed appearance dates showed a high concordance (on average six days difference). Finally, the political of impact a variation of a few days on calculated pesticide concentration was analyzed. Exemplarily, the pesticide fate model FOCUS PEARL was used to estimate pesticide groundwater concentrations. When calculating concentrations for application dates varying by ± two weeks, concentrations in groundwater usually varied very little. The highest variation was found for application at BBCH 30 in maize (6.6 % variation over all scenarios). These results showed that the uncertainty included in the estimation of appearance dates of BBCH stages for other countries has a relatively small effect on the results of PEARL and consequentially on the decision of the pesticide risk assessment by changing only the application date. 相似文献
294.
295.
Investigations of occupational and environmental risk caused by the use of agrochemicals have received considerable interest over the last decades. And yet, in developing countries, the lack of staff and analytical equipment as well the costs of chemical analyses make it difficult, if not impossible, to monitor pesticide contamination and residues in humans, air, water, and soils. A new and simple method is presented here for estimation of pesticide deposition in humans and soil after application. The estimate is derived on the basis of water mass balance measured in a given number of high absorbent papers under low evaporative conditions and unsaturated atmosphere. The method is presented as a suitable, rapid, low cost screening tool, complementary to toxicological tests, to assess occupational and environmental exposure caused by knapsack sprayers, where there is a lack of analytical instruments. This new method, called the “weight method”, was tested to obtain drift deposition on the neighbouring field and the clothes of the applicator after spraying water with a knapsack sprayer in one of the largest areas of potato production in Colombia. The results were confirmed by experimental data using a tracer and the same set up used for the weight method. The weight method was able to explain 86% of the airborne drift and deposition variance. 相似文献
296.
Pharmaceutically active compounds (PhACs) are commonly found in wastewater influent. However, little research has focused on determining their impact on fundamental processes in wastewater treatment such as nitrogen removal. In this study, focus was placed on 4 commonly occurring PhACs (ketoprofen, naproxen, carbamazepine and gemfibrozil). Their effect was ascertained in the ammonia oxidizing bacterium (AOB), Nitrosomonaseuropaea in terms of membrane integrity and nitrite production. These PhACs were shown to inhibit nitrite production at concentrations of 1 and 10 μM while no effect was observed at 0.1 μM. The maximum observed nitrification inhibition was 25%, 29%, 22% and 26% for ketoprofen, naproxen, carbamazepine and gemfibrozil, respectively. A decrease in the live/dead ratio ranging from 10% to 16% suggests that these PhACs affect membrane integrity in N.europaea. The difference in nitrite production between PhACs treated cells and non PhAC treated controls was still significant following washing suggesting that inhibition is irreversible. Finally, nitrite production when adjusted to the live fraction of cells was also found to decrease suggesting that PhACs inhibited the activity of surviving cells. These results suggest that the presence of PhACs may affect AOB activity and may impact nitrogen removal, a key function in wastewater treatment. Follow up studies with additional AOB and in mixed culture are needed to further confirm these results. 相似文献
297.
This study presents the microbiological characterization of the anaerobic sludge used in a two-stage anaerobic reactor for the treatment of organic fraction of urban solid waste (OFUSW). This treatment is one alternative for reducing solid waste in landfills at the same time producing a biogas (CH(4) and CO(2)) and an effluent that can be used as biofertilizer. The system was inoculated with sludge from a wastewater treatment plant (WWTP) (Río Frío Plant in Bucaramanga-Colombia) and a methanogenic anaerobic digester for the treatment of pig manure (Mesa de los Santos in Santander). Bacterial populations were evaluated by counting groups related to oxygen sensitivity, while metabolic groups were determined by most probable number (MPN) technique. Specific methanogenic activity (SMA) for acetate, formate, methanol and ethanol substrates was also determined. In the acidogenic reactor (R1), volatile fatty acids (VFA) reached values of 25,000 mg L(-1) and a concentration of CO(2) of 90%. In this reactor, the fermentative population was predominant (10(5)-10(6)MPN mL(-1)). The acetogenic population was (10(5)MPN mL(-1)) and the sulphate-reducing population was (10(4)-10(5)MPN mL(-1)). In the methanogenic reactor (R2), levels of CH(4) (70%) were higher than CO(2) (25%), whereas the VFA values were lower than 4000 mg L(-1). Substrate competition between sulphate-reducing (10(4)-10(5)MPN mL(-1)) and methanogenic bacteria (10(5)MPN mL(-1)) was not detected. From the SMA results obtained, acetoclastic (2.39 g COD-CH(4)g(-1)VSS(-1)day(-1)) and hydrogenophilic (0.94 g COD-CH(4)g(-1)VSS(-1)day(-1)) transformations as possible metabolic pathways used by methanogenic bacteria is suggested from the SMA results obtained. Methanotrix sp., Methanosarcina sp., Methanoccocus sp. and Methanobacterium sp. were identified. 相似文献
298.
Claudia Dreller 《Behavioral ecology and sociobiology》1998,43(3):191-196
Every recruitment system in social insects requires some individuals that serve as scouts, foragers that search independently
for food sources. It is not well understood which factors influence whether an individual becomes a scout or a recruit, nor
how the division of labor between the two forager groups is regulated. It is shown here for honeybees (Apis mellifera), using two different molecular techniques, that there is a genetically based difference in the probability that individuals
will scout independently for food. In contrast to earlier suggestions, experimental tests showed that the age of a bee does
not seem to influence its probability of becoming a scout or a recruit. Furthermore, scout bees do not search opportunistically
for either pollen or nectar but, rather, individuals have preferences that are genetically based. These findings are discussed
in the framework of foraging regulation by specialization in honeybees and the adaptive significance of polyandry.
Received: 23 October 1997 / Accepted after revision: 10 April 1998 相似文献
299.
Transformation of diclofenac by the indigenous microflora of river sediments and identification of a major intermediate 总被引:1,自引:0,他引:1
Diclofenac is a non-steroidal anti-inflammatory drug, which tends to be relatively persistent in the environment. Now, a fixed-bed column bioreactor filled with sediment from the creek Münzbach (Freiberg/Saxony) under aerobic conditions showed rapid removal of diclofenac in a concentration range of 3-35 microM without previous adaptation. The conversion of higher concentrations up to 260 microM was accompanied by conspicuously decreased turnover rates indicating a toxic effect of this drug or its resulting metabolic burden on the indigenous microflora. A major metabolite occurred transiently and was identified by NMR and MS to be the p-benzoquinone imine of 5-hydroxydiclofenac. Abiotic adsorption to the biofilm was shown to determine the further fate of this reactive product of 5-hydroxydiclofenac (aut-)oxidation. The apparent lack of a degradative potential for this compound as well as the failure to detect an enrichment of diclofenac-depleting microbial activity both indicate a cometabolic nature of diclofenac transformation. 4'-Hydroxy-diclofenac, the favoured transformation product of eucaryotic diclofenac metabolism, could not be identified. The ability to convert diclofenac was shown to be widespread among biofilms from different river sediments, but measured rates obviously do not correlate with the total microbial activity. In addition, application of sediments from locations exposed to communal waste water effluents did not indicate any form of adaptation measured as an increased specific diclofenac depletion rate. 相似文献
300.
Monica Wäber Claudia Dietl Jutta Köhler Ludwig Peichl 《Environmental Sciences Europe》1998,10(5):276-280
The combination of biomonitoring with standardized grass cultures and deposition monitoring of antimony (Sb), lead (Pb) and 12 polycyclic aromatic hydrocarbon compounds (PAH) was carried out in the conurbation of Munich, Germany in 1993 and resumed at the German-Czech border in 1995. Results from different location types in different areas and years seem to be comparable for Sb and PAH, because relevant background data fit in the same range. Biomonitoring reveals a seasonal course of PAH accumulation. Mean PAH contents are found to be significantly higher in grass cultures at locations along heavily traveled roads, compared to sites in living areas or in a rural background. The traffic related PAH bioaccumulation of both regions fits in the same range, although traffic composition is different and traffic density is ten times smaller at the German-Czech border. Correlation of Pb and Sb bioaccumulation in grass vs. deposition suggested abrasions of brake linings and tires to be one possible emission source. This might be the explanation for the mean contents of Pb and Sb in grass cultures at traffic locations in Munich exceeding those in living or rural areas. Deposition (Bergerhoff method) indicates analogous pollution dynamics in association with traffic. Pb bioaccumulation and deposition along the main roads at the German-Czech border show wider ranges compared to Munich. On the whole, Pb and Sb values at border traffic are found to be lower than those in Munich two years previously. 相似文献