Simultaneous partial nitrification, anammox and denitrification (SNAD) process was developed in a sequential batch reactor (SBR) and the influence of hydraulic retention time (HRT) on the SNAD process was investigated. Around 96% NH(4)(+)-N removal and 87% COD removal were observed at 9 d HRT. Marginal decreases in the removal efficiencies were observed when the HRT was reduced to 3d or the loa...

Agriculture and livestock production systems are two major emitters of greenhouse gases. Methane with a GWP (global warming potential) of 21, and nitrous oxide (N2O) with a GWP of 300, are largely emitted from animal production agriculture, where livestock production is based on pasture and feed grains. The principal biological processes involved in N2O emissions are nitrification and denitrifi...

In the early 1980s, nitrogen (N) deposition was first postulated as a cause of N saturation and spruce mortality across the northeastern US. In 1988, a series of high elevation spruce-fir forest N addition plots were established on Mt. Ascutney (southeastern) Vermont to test this hypothesis. The paired plots each received, in addition to ambient N deposition, 15.7 kg N ha-' (low N addition), 31...

utilization patterns (Dilly, 2001), the microbial community structure (e.g., proportions of bacteria to fungi) The barometric process separation (BaPS) and 15N dilution tech(Klein, 1977) and abiotic factors such as soil moisture– niques were used to determine gross nitrification rates on the same soil cores from an old grassland soil. The BaPS-technique separates temperature relationships (Klei...

Molecular approaches have revealed considerable diversity and uncultured novelty in natural prokaryotic populations, but not direct links between the new genotypes detected and ecosystem processes. Here we describe the influence of the structure of communities of ammonia-oxidizing bacteria on nitrogen cycling in microcosms containing natural and managed grasslands and amended with artificial sh...

Cell-specific ammonia oxidation rate (AOR) has been suggested to be an indicator of the performance of nitrification reactors and to be used as an operational parameter previously. However, published AOR values change by orders of magnitude and studies investigating full-scale nitrification reactors are limited. Therefore, this study aimed at quantifying ammonia-oxidizing bacteria (AOB) and est...

We studied controls on nitrification in an undisturbed water-limited ecosystem by inhibiting autotrophic nitrifying bacteria in soils with varying levels of vegetative cover. The activity of nitrifying bacteria was disrupted using nitrapyrin, 2-chloro-6-(trichloromethyl)-pyridine, under field conditions in three microenvironments (underneath shrubs, next to grasses and in bare soil). Ammonia-ox...

Nitrification was studied with microsensors and fluorescence in situ hybridization (FISH) in sandy sediment of a small lowland stream. Comparative measurements were performed in both intact field sediment (‘natural sediment’) and sediment from the same site after processing for a laboratory incubation experiment (‘manipulated sediment’). In natural sediment, the nitrification activity and abund...

In order to elucidate and quantify nitrogen transformations occurring during aerobic treatment of pig slurry, two laboratory experiments were carried out with contrasting levels of aeration, high level (experiment 1) and low level (experiment 2) of aeration. During these experiments, after reaching steadystate conditions, a single pulse of NO3 -N tracer was added directly to the reactor. When n...