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Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily--and this limits our ability to predict how soils will respond to climate change. Recent analytical and experimental advances have demonstrated that molecular structure alone does not control SOM stability: in fact, environmental and biological controls predominate. Here we propose ways to include this understanding in a new generation of experiments and soil carbon models, thereby improving predictions of the SOM response to global warming., Understanding soil biogeochemistry is essential to the stewardship of ecosystem services provided by soils, such as soil fertility (for food, fibre and fuel production), water quality, resistance to erosion and [...]

Long-term effects of forest dieback on soil organic matter (SOM) pools in an unmanaged high-elevation Norway spruce [Picea abies (L.) H. Karst.] forest were investigated by comparing three dieback sites with three adjacent sites with healthy spruce. The aim was to assess the long-term biogeochemical impact of a major disturbance in unmanaged forest ecosystems due to potential modification of their soil organic carbon (OC) pool. The spruces at the dieback sites had been killed by a bark beetle (Ips typographus) infestation 25 yr ago. Total OC stocks in the topsoil of all sites were determined; different OC pools were quantified by density/particle-size fractionation and [sup.13]C cross polarization magic angle spinning nuclear magnetic resonance (CPMAS NMR) spectroscopy. Additionally, the aboveground and belowground plant-derived OC input was quantified and the OC species were analyzed. The forest floor at the dieback sites showed significantly lower OC stocks, storing

University researchers from Germany examined the composition of total organic carbon from municipal solid waste samples using nuclear magnetic resonance spectroscopy and studies its behavior when composted in a landfill.

A new PCR primer system that targets a wide range of polycyclic aromatic hydrocarbon ring-hydroxylating dioxygenase ([PAH-RHD.[alpha]]) gene of both Gram-positive and Gram-negative bacteria was developed and used to study their abundance and diversity in two different soils in response to phenanthrene spiking. The results obtained from the analysis of amplicons confirmed the specificity of the newly developed primer system and revealed a soil type-dependent response of [PAH-RHD.sub.[alpha]] gene-carrying soil bacteria to phenanthrene spiking.

Various studies are conducted to determine the relationship that exists between the plant carbon resources and nitrogen content and the ectomycorrhizal fungal (EMF) diversity observed in the old-growth beech forest. The diversity of the species is shown to remain completely unaffected by the disruption of the carbon supply.

Considers the macromolecular organic composition of plant and microbial residues as inputs to soil organic matter (SOM). Factors for controlling humidification processes in soils; Emphasis on the organic chemical composition of the parent material for SOM formation; Identification of changes occurring during biodegradation of plant litter in soils; Amount, proportion and distribution of plant residues in soil.

On-line solid phase extraction with C-18 cartridges provided a reliable method for the extraction of polycyclic aromatic hydrocarbons (PAHs) from soil column effluents. The on-line extraction was compared to the common off-line extraction of effluent fractions with respect to the mass recoveries of an internal standard. The effluent was obtained from a water unsaturated soil column under steady state water flow conditions. The column was packed with an artificially anthracene-contaminated soil material. Our results showed superior and more reproducible PAH trapping when the on-line extraction was used. The PAH mass recoveries were unaffected by the range of dissolved organic carbon (DOC) concentrations covered in the experiment. This held true overa range of pHs and water unsaturated conditions of the C-18 material. By using the on-line extraction procedure, losses of PAHs due to sorption to the surfaces of collection vessels were avoided. The combination with a fraction collector allowed for the extraction of very small simple volumes. Thus, the method is suitable for an unbiased evaluation of PAH mobility in soil column experiments. [ABSTRACT FROM AUTHOR]