Influence of Compact Clay Layer on the Seepage Performance of the Municipal Solid Waste Landfills

The pollutants in the municipal solid waste landfill leachate result in severe damage to the environment of the groundwater and the soil beneath the municipal solid waste landfill. The liner systems with a low leakage performance are commonlly adopted under the municipal solid waste landfills to stop the contaminants of the leachate from polluting the environment. Even there are the rigorous demands in related specifications for the design of the liner system in the landfill. Pollution of the groundwater and the soil beneath the landfill still occurred in a large number of rubbish landfills because of the seepage. To investigate the influence of the compact clay layer (CCL) on the seepage performance of the liner systems, parametric analyses are conducted to study the influence of the thickness of CCL and the hydraulic conductivity of CCL on the leakage performance of the liner system. In conclusion, some suggestions for the design of the municipal solid waste landfills are proposed based on the analyses results.

Ctenocheloides almeidai sp. nov., a new ghost shrimp from Brazil (Decapoda, Ctenochelidae)

A second species of the ctenochelid genus Ctenocheloides Anker, 2010 is described based on a single female specimen collected on a rocky reef in front of Maceió, Alagoas, northeastern Brazil. Ctenocheloides almeidai sp. nov. represents the first record of Ctenocheloides in the Atlantic Ocean. The new species differs from C. attenboroughi Anker, 2010, the type species from Madagascar, in the number of teeth in the crista dentata of the third maxilliped, the proportions and ar-mature of the major and minor chelipeds, and several other characters. The microhabitats of C. almeidai sp. nov. and C. attenboroughi are remarkably similar: both species inhabit burrows made in rock crevices cemented by compact clay-like silt, at very shallow depths (1–1.5 m). A key to the western Atlantic species of the family Ctenochelidae is provided.

Iron bands, fragipans and duripans in the northeastern plateaus of Brazil — properties and genesis

Iron bands, fragipans and duripans are common in yellow low-activity clay soils developed from the Barreiras Group in coastal plateaus of northeastern Brazil. Such indurated horizons are found in depressions of the plateaus where sugar cane growth is greatly reduced. Little research has being done on the nature of their bonding agents and their genesis. Research carried out in arid zones has frequently attributed duripan consistency to amorphous silica; however, duripans in northeast Brazil occur under higher rainfall (1500–2000 mm). The objective of this work was to study the nature and distribution of soil features in a plateau to better understand the processes associated with soil hardening. Two transects, across a small and a large depression, were investigated using field soil characterisation, micromorphological techniques, and mineralogical and geochemical analyses.The formation of the indurated horizons studied is due to two sequential processes: development of aquic conditions and incipient podzolization. Such processes have affected the upper part of a thin (<0.6 m in small depressions) or thick (>0.6 m in large depressions) compact clay horizon, showing horizontal plans likely inherited from the sediment. Onset of aquatic conditions formed the first fragipans overlying iron bands. Later, aquic conditions are combined with incipient podzolization to produce bleached loose horizons overlying duripans and iron bands. As the bonding agents in the duripans are organo-metallic complexes, these duripans appear to be very different from those described in arid environments. Key words: Low activity clay Ultisols, Barreiras Group, iron bands, fragipans and duripans, organo-metallic complexes