Obscured Binary Quasar Cores in SDSS J104807.74+005543.5?

We report the discovery of a possible close binary system of quasars in SDSS J1048+0055. The [OIII]4959,5007 emission lines are clearly double-peaked, and two discrete radio sources with a projected physical separation of ~20 pc are found in the VLBA milliarcsec resolution image at 8.4 GHz. Each of the [O III]4959,5007 doublets and Hbeta can be well modelled by two Gaussians and the line ratio, [O III]5007/Hbeta ~7, is typical of Seyfert 2 galaxies. No broad component of Hbeta was detected and its [O III]5007 luminosity, L_[OIII] ~ 9.2 times 10^42 erg s^-1, is comparable to luminous quasars and is a few ten times more luminous than typical Seyfert galaxies. One natural interpretation is that SDSS J1048+0055 contains two close quasar-like nuclei and the BLR around them are obscured. Other possible models are also discussed. We suggest that double-peaked narrow emission line profile may be an effective way of selecting candidates of binary black holes with intermediate separation

Impacts of Extreme Precipitation Events on Performance of Conservation Practices

Climate-induced changes in the volume and erosive power of precipitation is the most important effect of global climate change on soil erosion and surface runoff (Nearing, 2001). Greater frequency and intensity of extreme weather events have been observed in the last decades due to the climate change (Milly et al., 2002; SWCS, 2003). One of the direct consequences of those extreme events on agricultural land is the acceleration of topsoil loss, which leads to soil degradation and pollutant transport from the field. A linearly increase of the amount of daily precipitation by 5% or 10% could increase soil erosion by 10.7% and 35.6%, respectively (Savabi et al., 1993). In addition, the risk of gully erosion and stream channel erosion are also increased during the extreme events. Consequently, a more severe and lasting damage to soil and water resources can be caused from these forms of erosion, which require more intensive and costly conservation treatments (SWCS, 2003)

Effectiveness of variable-width buffer design for sediment reduction

Vegetative buffer strips are vegetated areas (usually strips) between fields and waterbodies that can mitigate the effects of agricultural activities by acting as a physical barrier to sediment and nutrients being carried to streams, and thereby have been widely used as a best management practice (BMP). Buffers can slow surface water flow and allow greater water infiltration, trapping the sediment entering from cultivated areas. In addition, research has documented the ability of buffers to removing pollutants from surface runoff and/or shallow groundwater (Lin et al., 2007; Ryder and Fares, 2008). For example, nitrogen can be removed by plant uptake or by microorganism denitrification within buffers (Lowrance and Hubbard, 2001)