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41.
Changes in stream water quality due to logging of the boreal forest in the Montmorency Forest,Québec
Yohann Tremblay Alain N. Rousseau André P. Plamondon Denis Lévesque Marcel Prévost 《水文研究》2009,23(5):764-776
Summer stream water quality was monitored before and following the logging of 50% of the boreal forest within three small watersheds (<50 ha) nested in the ‘Ruisseau des Eaux‐Volées’ Experimental Watershed, Montmorency Forest (Québec, Canada). Logging was conducted in winter, on snow cover according to recommended best management practices (BMPs) to minimize soil disturbance and protect advance growth. A 20‐m forest buffer was maintained along perennial streams. In watershed 7·2, cut‐blocks were located near the stream network and logging was partially allowed within the riparian buffer zone. In watersheds 7·5 and 7·7, logging occurred farther away from the stream network. Observations were also made for watershed 7·3 that collected the runoff from watersheds 7·2 and 7·5, and watershed 7·6, the uproad portion of watershed 7·7. The control watershed 0·2 was contiguous to the impacted watersheds and remained undisturbed. Following clearcutting, changes in summer daily maximum and minimum stream temperatures remained within ± 1 °C while changes in diurnal variation did not decrease by more than 0·5 °C. Concentrations of NO3? greatly increased by up to 6000% and concentrations of K+ increased by up to 300% during the second summer after logging. Smaller increases were observed for Fetotal (up to 71%), specific conductance (up to 26%), and Mg2+ (up to 19%). Post‐logging pH decreased slightly by no more than 7% while PO43? concentration remained relatively constant. Suspended sediment concentrations appeared to increase during post‐logging, but there was not enough pre‐logging data to statistically confirm this result. Logging of moderate intensity and respecting established BMPs may account for the limited changes of water quality parameters and the low exceedances of the criteria for the protection of aquatic life. The proximity of the cutover to the stream network and logging within the riparian zone did not appear to affect water quality. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
42.
The AltiKa altimeter onboard SARAL is a joint CNES/ISRO mission launched in February 2013 that has the same 35 days repeat orbit of the previous European altimeters, Envisat, and ERS-1/2. SARAL/AltiKa is thus a unique opportunity to extend the repeat observations of this orbit that have been surveyed since 1991. However, the altimeter operates in Ka-band, which is higher than the previous frequencies, and offers new paths of investigation. The penetration depth is theoretically reduced from around 10 m in Ku-band to less than 1 m in Ka-band, such that the volume echo originates from the near subsurface. Second, the sharper antenna aperture leads to a narrower leading edge that reduces the impact of the ratio between surface and volume echoes of the height retrieval. Indeed, the spatial and temporal observations of AltiKa at cross-over points and along-track indicate that the impact of backscatter changes on the height decreasesfrom 0.3 m/dB for the Ku-band to only 0.05 m/dB for the Ka-band. Therefore, the height measurement is stable over time. Moreover, the volume echo in the Ka-band results from the near subsurface layer and is mostly controlled by ice grain size, unlike the Ku-band. 相似文献
43.
Adnand Bitri Jean-Pierre Brun Denis Gapais Florence Cagnard Charles Gumiaux Jean Chantraine Guillaume Martelet Catherine Truffert 《Comptes Rendus Geoscience》2010,342(6):448-452
We present results and interpretation of a 72 km long deep seismic reflection profile acquired across the internal zone of the Hercynian belt of South Brittany. The profile is of excellent quality, most of the crust being highly reflective. The “ARMOR 2 South” profile, is correlated with the “ARMOR 2 North” profile that was published in 2003. Correlation of the main subsurface reflections with surface geological and structural data provides important information about the crustal structure that resulted from thickening during Late Devonian and regional-scale extension during Late Carboniferous. In particular, seismics image shows a very high reflectivity zone, lying flat over more than 40 km at about 10–12 km depth. This zone is interpreted as a major zone of ductile crustal thinning. 相似文献
44.
Philip J. Wallis Michael B. Ward Jamie Pittock Karen Hussey Howard Bamsey Amandine Denis Steven J. Kenway Carey W. King Shahbaz Mushtaq Monique L. Retamal Brian R. Spies 《Climatic change》2014,125(2):209-220
A variety of proposed activities to mitigate greenhouse gas emissions will impact on scarce water resources, which are coming under increasing pressure in many countries due to population growth and shifting weather patterns. However, the integrated analysis of water and carbon impacts has been given limited attention in greenhouse mitigation planning. In this Australian case study, we analyse a suite of 74 mitigation measures ranked as highest priority by one influential analysis, and we find that they have highly variable consequences for water quantity. We find: (1) The largest impacts result from land-based sequestration, which has the potential to intercept large quantities of water and reduce catchment yields, estimated to exceed 100 Mm3/MtCO2-e of carbon mitigated (100,000 l per tonne CO2-e). (2) Moderate impacts result from some renewable power options, including solar thermal power with a water cost estimated at nearly 4 Mm3/MtCO2-e. However, the water impacts of solar thermal power facilities could be reduced by designing them to use existing power-related water supplies or to use air or salt-water cooling. (3) Wind power, biogas, solar photovoltaics, energy efficiency and operational improvements to existing power sources can reduce water demand through offsetting the water used to cool thermal power generation, with minor savings estimated at 2 Mm3/MtCO2-e and amounting to nearly 100 Mm3 of water saved in Australia per annum in 2020. This integrated analysis significantly changes the attractiveness of some mitigation options, compared to the case where water impacts are not considered. 相似文献
45.
N. Peyraube R. Lastennet A. Denis P. Malaurent J. D. Villanueva 《Environmental Earth Sciences》2014,72(10):4207-4215
Saturation index with respect to calcite (SIc) and equilibrium CO2 partial pressure are important parameters to study groundwater in limestone aquifers. Aside from their use in time series, CO2 and SIc are used to estimate the baseline of CO2 in the vadose zone. The objective of this paper is to present conceptual examples on the use of the CO2–SIc relationship to have new information from usual parameters. Case study was considered as an example of use from Cussac site, a limestone aquifer in southwest of France. The result showed that CO2 baseline in unsaturated zone is found close to 25,000 ± 1,000 ppm. 相似文献
46.
Jun-Hui Fan Denis Bastieri Jiang-He Yang Yi Liu Tong-Xu Hua Yu-Hai Yuan De-Xiang Wu 《中国天文和天体物理学报》2014,(9)
We selected 457 blazars(193 flat spectrum radio quasars, 61 lowsynchrotron peaked blazars, 69 intermediate-synchrotron peaked blazars and 134high-synchrotron peaked blazars) from the second Fermi-LAT catalog(2FGL) of γ-ray sources, which have X-ray observations. We calculated the lower limits for their Doppler factors, δγ, and compared the lower limits with the available Doppler factors and the apparent superluminal velocities in the literature. 相似文献
47.
The osmotic coefficients of FeCl3 at 25 °C from 0.15 to 1.7 m [Rumyantsev et al., Z. Phys. Chem., 218, 1089-1127, 2004] have been used to determine the Pitzer parameters (β(0), β(1) and C?) for FeCl3. Since the differences in the Pitzer coefficients of rare earths in NaCl and NaClO4 are small, the values of Fe(ClO4)3 have been estimated using the differences between La(ClO4)3 and LaCl3. The Pitzer coefficients for FeCl3 combined with enthalpy and heat capacity data for the rare earths can be used to estimate the activity coefficients of Fe3+ in NaCl over a wide range of temperatures (0 to 50 °C) and ionic strength (0 to 6 m).The activity coefficients of Fe3+ in NaCl and NaClO4 solutions have been used to determine the activity coefficients of Fe(OH)2+ in these solutions from the measured first hydrolysis constants of Fe3+ [Byrne et al., Mar. Chem., 97, 34-48, 2005]. The activity coefficients of , Fe(OH)3 and from 0 to 50 °C have also been determined from the solubility measurements of Fe(III) in NaCl solutions [Liu and Millero, Geochim. Cosmochim Acta, 63, 3487-3497, 1999]. These activity coefficients have been fitted to the Pitzer equations. These results can be used to estimate the speciation of Fe(III) with OH− in natural waters with high concentrations of NaCl from 0 to 50 °C. 相似文献
48.
Young Nathan L. Lemieux Jean-Michel Locat Pascal Demers Denis Delottier Hugo Mony Laura 《Hydrogeology Journal》2022,30(4):1337-1344
Hydrogeology Journal - An extensive network of multilevel vibrating-wire piezometers (VWP) was recently created to monitor the spatial and temporal variation of pore pressure (and hydraulic head)... 相似文献
49.