Relatively little is currently known about the spatiotemporal variability of land surface conditions during the North American monsoon, in particular for regions of complex topography. As a result, the role played by land-atmosphere interactions in generating convective rainfall over steep terrain and sustaining monsoon conditions is still poorly understood. In this study, the variation of hydrometeorological conditions along a large-scale topographic transect in northwestern Mexico is described. The transect field experiment consisted of daily sampling at 30 sites selected to represent variations in elevation and ecosystem distribution. Simultaneous soil and atmospheric variables were measured during a 2-week period in early August 2004. Transect observations were supplemented by a network of continuous sampling sites used to analyze the regional hydrometeorological conditions prior to and during the field experiment. Results reveal the strong control exerted by topography on the spatial and temporal variability in soil moisture, with distinct landscape regions experiencing different hydrologic regimes. Reduced variations at the plot and transect scale during a drydown period indicate that homogenization of hydrologic conditions occurred over the landscape. Furthermore, atmospheric variables are clearly linked to surface conditions, indicating that heating and moistening of the boundary layer closely follow spatial and temporal changes in hydrologic properties. Land-atmosphere interactions at the basin scale (ϳ100 km 2 ), obtained via a technique accounting for topographic variability, further reveal the role played by the land surface in sustaining high atmospheric moisture conditions, with implications toward rainfall generation during the North American monsoon.

Soil moisture distributions are expected to be closely tied to ecosystem processes in water-limited environments of the southwest United States. Nevertheless, few studies have addressed how soil moisture varies across grassland to forest transitions frequently observed in semiarid mountain settings. In this study, we quantify the vegetation controls on surface soil moisture by sampling a range of different ecosystems present in the Valles Caldera, New Mexico. Soil and atmospheric variables were measured during a 2-week field campaign conducted in late July to early August 2005 during the North American monsoon. Field observations were supplemented by a network of continuous instruments used to assess conditions prior to and after the sampling campaign. Results reveal that soil moisture responds directly to summer precipitation events and is mediated by plant interception, which differs across the grassland-forest continuum. The nature of the spatial and temporal variations in soil moisture changes across the different sampled ecosystems: wetlands, riparian forests, grasslands, ponderosa, deciduous and mixed conifer forests. In particular, statistical analyses of soil moisture distributions indicate that distinct regimes (e.g. probability density functions) exist along the semiarid vegetation gradient, which may not be revealed through simple metrics such as the ecosystem average. Ecosystem differences are further elucidated through comparison of the spatial variations in each vegetation type, indicating higher variability in wetland and grassland sites.

Water impact: MET biofilters outperform gravel biofilters in wastewater treatment and will reduce the surface for CW, selecting certain genera of bacteria reported to be electroactive.

We studied the influence of six edaphic biostimulants/biofertilizers (BSs) manufactured by the pH-stat method from different sewage sludge (SS): SS1 (an anaerobic mature sludge, one year old), SS2 (an aerobic young sludge, without maturation) and SS3 (an aerobic mature sludge, four months old), not previously autoclaved (A) and autoclaved (B), by analysing their effects on soil biological properties. Soil enzymatic activities were measured at 1, 3, 5, 7, 15, 30 and 60 days of the incubation period, whereas the 16S rDNA-DGGE profiles were determined at 0, 5 and 60 days. The enzymatic activities were significantly stimulated. The highest stimulation was found in the B2 treatment followed by B3, A2, A3, B1 and A1 treatments. Increasing the number of lower molecular weight proteins in the BS enhances the stimulation of soil enzymatic activities. The application of BS caused at 5 days of the incubation period temporal variations in the soil bacterial community structure.