Landfill covers are critical to waste containment, yet field performance of specific cover designs has not been well documented and seldom been compared in side-by-side testing. A study was conducted to assess the ability of landfill final covers to control percolation into underlying waste. Conventional covers employing resistive barriers as well as alternative covers relying on water-storage ...

Substantial tracts of land in the southwestern and western U.S. are undergoing or will require ERA. Toxicity bioassays employed in baseline ERAs are, for the most part. representative of mesic systems, and highly standardized test species (e.g., lettuce, earthworm) are generally not relevant to arid system toxicity testing. Conversely, relevant test species are often poorly characterized with r...

introduction various factors like climatic conditions, vegetation, soil properties, topography, time, plant residue quality and crop management strategies affect the decomposition rate of organic carbon (oc) and its residence time in soil. plant residue management concerns nutrients recycling, carbon recycling in ecosystems and the increasing co2 concentration in the atmosphere. plant residue d...

Since about 30 % of the land surface are covered with arid and desert conditions of soil, bright grounds and their aerosol emissions are of essential importance for the investigation of general aerosol impact in climate. Therefore retrievals of aerosol properties from spaceborne platforms need to include retrieval approaches, working over this conditions. An approach to retrieve aerosol propert...

Climatological background Life in the semiarid Sahel belt of tropical North Africa strongly depends on the availability of water and has been repeatedly affected by shifts to more arid climate. The most recent drought occurred in the early 1970’s and 1980’s, with partial recovery during the late 1990’s. High resolution fluvial sediments off Senegal offer the opportunity to study the history of ...

In arid and semiarid regions most of the solar radiation penetrates through the canopy and reaches the ground, and hence the turbulent exchange coefficient under canopy Cs becomes important. The use of a constant Cs that is only appropriate for thick canopies is found to be primarily responsible for the excessive warm bias of around 10 K in monthly mean ground temperature over these regions in ...

We integrate climatic niche models and dated phylogenies to characterize the evolution of climatic niches in Oenothera sections Anogra and Kleinia (Onagraceae), and from that we make inferences on diversification in relation to climate. The evolution of climatic tolerances in Anogra + Kleinia has been heterogeneous, across phylogenetic groups and across different dimensions of climate. All the ...

The temporal dynamics of vegetation biomass are of key importance for evaluating the sustainability of arid and semiarid ecosystems. In these ecosystems, biomass and soil moisture are coupled stochastic variables externally driven, mainly, by the rainfall dynamics. Based on long-term field observations in northwestern (NW) China, we test a recently developed analytical scheme for the descriptio...