Influence of Freshwater Sediment Characteristics on Persistence of Fecal Indicator Bacteria     

Laurence Haller  Essoêfli Amedegnato  John Poté  Walter Wildi 《Water, air, and soil pollution》2009,203(1-4):217-227

Extended persistence of enteric bacteria in coastal sediments and potential remobilization of pathogens during natural turbulence or human activities may induce an increased risk of human infections. In this study, the effect of sediment characteristics such as particle grain size and nutrient and organic matter contents on the survival of fecal indicator bacteria (FIB) including total coliforms, Escherichia coli, and Enterococcus was investigated. The experimentation was carried out for 50 days in microcosms containing lake water and different contaminated freshwater sediments in continuous-flow and batch conditions. Results of this study revealed: (1) extended FIB survival in sediments up to 50 days, (2) higher growth and lower decay rates of FIB in sediments with high levels of organic matter and nutrients and small (mainly silt) grain size, and (3) longer survival of Enterococcus sp. compared to E. coli and total coliforms. FIB survival in sediments and possible resuspension are of considerable significance for the understanding of permanent microbial pollution in water column and therefore human risk during recreational activities.  相似文献   

Amphoteric Surfactants for PAH and Lead Polluted-Soil Treatment Using Flotation     

Mouton  Julia  Mercier  Guy  Blais  Jean-François 《Water, air, and soil pollution》2009,199(1-4):381-387

Water, Air, & Soil Pollution - Nineteen soil samples (SE Spain) with very different chemical physical properties and developed over different parent materials were contaminated by adding...  相似文献   

Effect of nitrogen fertilization on nitrogen dynamics in oilseed rape using 15N‐labeling field experiment     

Julie Gombert  Frédérik Le Dily  Jérémy Lothier  Philippe Etienne  Laurence Rossato  Jean‐Michel Allirand  Alexandra Jullien  Alexandre Savin  Alain Ourry 《植物养料与土壤学杂志》2010,173(6):875-884

In order to optimize nitrogen (N) fertilization and to reduce the environmental impact of oilseed rape without decreasing yield, a clearer understanding of N dynamics inside the plant is crucial. The present investigation therefore aimed to study the effects of different N‐application rates on the dynamics of N uptake, partitioning, and remobilization. The experiment was conducted on winter oilseed rape (Brassica napus L. cv. Capitol) under three levels of N input (0, 100, and 200 kg N ha^–1) from stem elongation to maturity using ¹⁵N‐labeling technique to distinguish between N uptake and N retranslocation in the plant. Nitrogen fertilization affected the time‐course of N uptake and also the allocation of N taken up from flowering to maturity. Most pod N came from N remobilization, and leaves accounted for the largest source of remobilized N regardless the N‐application rate. However, the contribution of leaves to the remobilized N pool increased with the N dose whereas the one of taproot decreased. Stems were the main sink for remobilized N from stem elongation to flowering. Leaves remained longer on N200 than on N0 and N100 plants, and N concentration in fallen leaves increased with the N treatment and in N100 plants along an axial gradient from the basal to the upper leaves. Overall, these results show that the timing of N supply is more crucial than the N amount to attain a high N efficiency.  相似文献   

Determination of specific gravity of green Pinus taeda samples by near infrared spectroscopy: comparison of pre-processing methods using multivariate figures of merit     

Christian R. Mora  Laurence R. Schimleck 《Wood Science and Technology》2009,43(5-6):441-456

Near infrared diffuse reflectance was used for the determination of specific gravity in green Pinus taeda L. wood samples representing simulated increment cores obtained at breast height and merchantable green logs. The effects of using three pre-processing methods (second derivative, multiplicative scatter correction, and orthogonal signal correction) to reduce the scatter observed in the original spectra were evaluated. The effectiveness of each method was assessed in terms of the average predictive ability of the models and in terms of multivariate figures of merit derived from net analyte signal theory. Specific gravity was successfully modeled using green wood samples. No differences in predictive ability among models were found, although more parsimonious regressions were obtained using transformed spectra. The incorporation of figures of merit for the characterization of calibration models proved to be a valuable tool for understanding the effects of the pre-processing alternatives on the final results.  相似文献   

Specific gravity responses of slash and loblolly pine following mid-rotation fertilization     

Kimberly R. Love-Myers  Alexander Clark III  Laurence R. Schimleck  Eric J. Jokela  Richard F. Daniels 《Forest Ecology and Management》2009

Wood quality attributes were examined in six stands of slash pine (Pinus elliottii Engelm. var. elliottii) and loblolly pine (P. taeda L.) in the lower Coastal Plain of Georgia and Florida. Several plots comprised each stand, and each plot was divided so that it received three fertilizer treatments: a control treatment with herbaceous weed control at planting and brush control at mid-rotation only (control); 45 kg ha⁻¹ N + 56 kg ha⁻¹ P + herbaceous weed control at planting and 224 kg ha⁻¹ N + 45 kg ha⁻¹ P + brush control at mid-rotation (fertilizer with N at planting); and 56 kg ha⁻¹ P + herbaceous weed control at planting and 224 kg ha⁻¹ N + 45 kg ha⁻¹ P + brush control at mid-rotation (fertilizer without N at planting). Ring width, ring earlywood specific gravity (SG), ring latewood SG, whole ring SG, and ring percent latewood were measured on each of seven trees. Of these measurements, this study focused mainly on the properties related to SG. Examination of the rings showed that latewood SG was significantly lower in trees treated with fertilizers with and without N at planting in the two to three years following fertilization, but that latewood SG gradually returned to a level similar to the control. Fertilizer without N at planting may also have had a brief negative effect on earlywood SG following mid-rotation fertilization, but it was not as clear or lasting as the effect on latewood SG. Additionally, although slash and loblolly pine appear to differ in the developmental patterns of these SG properties, there were no significant differences in how these patterns interacted with treatment. This study demonstrated that fertilization treatments have similar short-term effects on the SG of slash and loblolly pines, particularly in latewood, but the trees will return to a SG pattern consistent with unfertilized trees within two or three years.  相似文献   

Sterile insect technique and <Emphasis Type="Italic">Wolbachia</Emphasis> symbiosis as potential tools for the control of the invasive species <Emphasis Type="Italic">Drosophila suzukii</Emphasis>     

Katerina Nikolouli  Hervé Colinet  David Renault  Thomas Enriquez  Laurence Mouton  Patricia Gibert  Fabiana Sassu  Carlos Cáceres  Christian Stauffer  Rui Pereira  Kostas Bourtzis 《Journal of pest science》2018,91(2):489-503

Drosophila suzukii, a vinegar fly originated from Southeast Asia, has recently invaded western countries, and it has been recognized as an important threat of a wide variety of several commercial soft fruits. This review summarizes the current information about the biology and dispersal of D. suzukii and discusses the current status and prospects of control methods for the management of this pest. We highlight current knowledge and ongoing research on innovative environmental-friendly control methods with emphasis on the sterile insect technique (SIT) and the incompatible insect technique (IIT). SIT has been successfully used for the containment, suppression or even eradication of populations of insect pests. IIT has been proposed as a stand-alone tool or in conjunction with SIT for insect pest control. The principles of SIT and IIT are reviewed, and the potential value of each approach in the management of D. suzukii is analyzed. We thoroughly address the challenges of SIT and IIT, and we propose the use of SIT as a component of an area-wide integrated pest management approach to suppress D. suzukii populations. As a contingency plan, we suggest a promising alternative avenue through the combination of these two techniques, SIT/IIT, which has been developed and is currently being tested in open-field trials against Aedes mosquito populations. All the potential limiting factors that may render these methods ineffective, as well as the requirements that need to be fulfilled before their application, are discussed.  相似文献   

Polycyclic Aromatic Hydrocarbon Oxidation from Concentrates Issued from an Attrition Process of Polluted Soil Using the Fenton Reagent and Permanganate     

Malika Bendouz  Justine Dionne  Lan Huong Tran  Lucie Coudert  Guy Mercier  Jean-François Blais 《Water, air, and soil pollution》2017,228(3):115

This study was conducted to determine the optimal conditions for PAH degradation from highly contaminated attrition sludge (PAC) using a Fenton process or successive permanganate (KMnO₄) oxidation and Fenton processes. The following parameters were studied to optimize the Fenton oxidation process: the amounts of reactants based on the stoichiometric oxidant demand (SOD), the reactant addition protocol and number of doses, and the solid/liquid ratio (S/L). The results showed that the following conditions were optimum: TS?=?30%, 7.5 times SOD, H₂O₂/Fe²⁺ ratio?=?10, and added five times during 60 min, which allowed the degradation of 43% of total 27 PAHs from the PAC. Successive Fenton and KMnO₄ oxidation processes were also tested. PAH degradation using a sequential Fenton process followed by KMnO₄ oxidation (or KMnO₄ followed by Fenton) was higher than for the use of Fenton or KMnO₄ treatment alone. Up to 71% of the total 27 PAHs were degraded when using a combination of both processes. It appeared that the sequential treatment is a viable method for the significant degradation of 27 PAHs from PAC (t value?>?2.77).  相似文献   

Diviner Lunar Radiometer observations of cold traps in the Moon's south polar region     

Paige DA  Siegler MA  Zhang JA  Hayne PO  Foote EJ  Bennett KA  Vasavada AR  Greenhagen BT  Schofield JT  McCleese DJ  Foote MC  DeJong E  Bills BG  Hartford W  Murray BC  Allen CC  Snook K  Soderblom LA  Calcutt S  Taylor FW  Bowles NE  Bandfield JL  Elphic R  Ghent R  Glotch TD  Wyatt MB  Lucey PG 《Science (New York, N.Y.)》2010,330(6003):479-482

Diviner Lunar Radiometer Experiment surface-temperature maps reveal the existence of widespread surface and near-surface cryogenic regions that extend beyond the boundaries of persistent shadow. The Lunar Crater Observation and Sensing Satellite (LCROSS) struck one of the coldest of these regions, where subsurface temperatures are estimated to be 38 kelvin. Large areas of the lunar polar regions are currently cold enough to cold-trap water ice as well as a range of both more volatile and less volatile species. The diverse mixture of water and high-volatility compounds detected in the LCROSS ejecta plume is strong evidence for the impact delivery and cold-trapping of volatiles derived from primitive outer solar system bodies.  相似文献   

Kernel regression methods for the prediction of wood properties of Pinus taeda using near infrared spectroscopy     

Christian R. Mora  Laurence R. Schimleck 《Wood Science and Technology》2010,44(4):561-578

Near infrared diffuse reflectance spectra collected in 10-mm sections were used for the estimation of air-dry density (AD), microfibril angle (MFA), stiffness (MOE), tracheid coarseness (COARS), and tracheid wall thickness (WTHICK) in wood radial strip samples obtained at breast height (1.4 m) from 60 Pinus taeda trees. Calibration models were developed using traditional partial least squares (PLS) and kernel regression. The kernel methods included radial basis functions-partial least squares (RBF-PLS) and least-squares support vector machines (LS-SVM). RBF-PLS and LS-SVM models outperformed PLS-CV calibrations in terms of fit statistics. MFA and MOE, two properties that exhibited nonlinearity, showed the most significant improvements compared to PLS. In terms of predictive ability RBF-PLS performed better than PLS for the prediction of MFA, MOE, and COARS. LS-SVM showed better prediction statistics in all cases, except for WTHICK that gave similar statistics compared to PLS and was superior to RBF-PLS. By adding statistically significant factors to the PLS regressions, it was possible to capture some of the nonlinear features of the data and improve the predictive ability of the PLS models.  相似文献   

Is spawning stock biomass a robust proxy for reproductive potential?          下载免费PDF全文

Laurence T Kell  Richard D M Nash  Mark Dickey‐Collas  Iago Mosqueira  Cody Szuwalski 《Fish and Fisheries》2016,17(3):596-616

Reference points based on fishing mortality (F) and spawning stock biomass (SSB) are a requirement of many fisheries management frameworks. SSB is assumed to be a proxy for stock reproductive potential (SRP). Limit reference points based on SSB are used to indicate the level of biomass below which productivity is affected. SSB fails to account for changes in fecundity, egg viability and sex ratio, and it has been argued that total egg production (TEP) provides a better reflection of SRP. We explore how accounting for TEP impacts limit reference points and evidence for a relationship between stock and recruit. Time series of SSB and TEP are compared for three North Sea stocks: cod (Gadus morhua), herring (Clupea harengus) and plaice (Pleuronectes platessa). Dynamics based on TEP are different from those based on SSB for cod and plaice, but the stock–recruit relationships were not ‘improved’ using TEP. Shifts in productivity (spawner per recruit) occur in all three time series and SSB underestimated uncertainty. Yet again, it was shown that assumptions of stationarity about fish population productivity are incorrect. We argue that the use of TEP does improve the realism in our understanding of stock dynamics, and demographically, more complex management strategy evaluation is required to develop management procedures that are robust to uncertainty and integrate F and the demographic health of a stock. Empirical feedback control systems based on fisheries independent indices including surveys of eggs, larvae, recruits, juveniles or spawning adults should be evaluated and compared to traditional approaches.  相似文献