Search results for "soil"

Retention of Molybdenum(VI) by Three Finnish Mineral Soils

1993

Retention of molybdate by three Finnish mineral soils from 10−4 and 10−5 M sodium molybdate solutions at room temperature was investigated at pH 2.3–7.5. In the adsorption experiments 0.02 M KCl wa...

Cover Picture: Design, Synthesis, and Miniemulsion Polymerization of New Phosphonate Surfmers and Application Studies of the Resulting Nanoparticles …

2012

High mitochondrial DNA sequence diversity in the parthenogenetic earthworm Dendrobaena octaedra

2010

Apomictic parthenogens are clonal organisms with limited genetic opportunity for increasing diversity beyond mutation. However, such species can be successful and have been shown to harbor more genetic diversity than might be expected. Here we surveyed diversity of the cytochrome oxidase subunit I gene from the mitochondrial genome of the earthworm Dendrobaena octaedra, an apomictic parthenogen. Diversity estimates made previously from allozyme markers for this species were high, but could have been affected by a detection bias, namely variable expression of alleles in the polyploid genome. We found similarly high mtDNA diversity over three localities in Finland, each represented by two sit…

Effects of temperature and moisture fluctuations on an experimental soil microarthropod community

2001

Summary We established an experiment in microcosms with coniferous forest humus and birch leaf litter for testing the effects of constant vs. diurnally fluctuating temperature and uniform vs. varying moisture, on the population densities and species richness of Collembola and Mestostigmata. These parameters and the vertical distribution of populations were analysed by layers (top, centre, bottom) at two samplings (weeks 10 and 27). The hypotheses were that populations of at least some species benefit from fluctuating microclimate, and that varying conditions permit more species to coexist than uniform conditions. At fluctuating temperature regime, four species and total Collembola were more…

Hydration and water holding properties of cross-linked lignite humic acids

2014

Abstract Lignite and lignite humic acids, which are used as soil amendments sometimes, are supposed to improve soil properties such as water holding capacity. The structure of those materials is composed of various organic molecules stabilized mostly by weak interactions. Therefore, excess of water causes only partial swelling, but most of the physical structure is destabilized. This accelerates the desiccation and hampers their application as natural hydrogel-like substances. In order to stabilize the structure of lignite humic acids and improve the water holding capacity, we applied formaldehyde cross-linking procedure based on covalent coupling of aromatic humic acids moieties. By combin…

Temporal and spatial fluctuations in moisture affect humus microfungal community structure in microcosms

2000

The effects of temporal and spatial fluctuations in moisture on the microfungal community were studied in birch litter plus pine humus microcosms over 6 months. Two treatments were used: a uniform treatment in which moisture was maintained at the original moisture content throughout the profile over the course of the experiment; and a fluctuating moisture treatment in which the moisture content of the whole microcosm fluctuated weekly around the original moisture content. At 6 months, fungal species richness was higher and diversity was lower under moisture fluctuations than under uniform moisture. The number of fungal isolates and proportional diversity was significantly higher in the bott…

Emissions and spatial variability of N2O, N2 and nitrous oxide mole fraction at the field scale, revealed with 15N isotopic techniques.

2006

Abstract The accurate measurement of nitrous oxide (N 2 O) and dinitrogen (N 2 ) during the denitrification process in soils is a challenge which will help to estimate the contribution of soil N 2 O emissions to global warming. Oxygen concentration, nitrate concentration and carbon availability are generally the main factors that control soil denitrification rate and the amount of N 2 O or N 2 emitted. The aim of this paper is to present a database of the N 2 O mole fraction measured at the field scale, and to test hypotheses concerning its regulation. A 15 N-nitrate tracer solution was added to 36 undisturbed soil cores on a 20 m×20 m cultivated field plot. Fluxes of CO 2 , N 2 O and N 2 f…

Isolation and characterisation of an isoproturon-mineralisingMethylopilasp. TES from French agricultural soil

2004

Using enrichment culture three isoproturon (IPU) mineralising bacterial isolates were isolated from a French agricultural soil mineralising up to 50% of the initially added 14C-ring labelled IPU within only eight days. These isolates showed similar metabolic (BIOLOG GN) and amplified rDNA restriction (ARDRA) profiles. Partial 16S rDNA sequencing revealed that they were identical and identified as Methylopila sp TES. This strain harbours a large plasmid (220 kb) putatively bearing essential IPU-degrading genes as demonstrated by a curing experiment. Methylopila sp. TES transformed IPU and its known metabolites to CO2 and biomass but did not degrade chlorotoluron, monolinuron, diuron and linu…

A new species of Pythium isolated from the Burgundy region in France.

1998

Pythium nodosum sp. nov. has been isolated from a soil sample taken in the Burgundy region in France. The fungus has spherical to variously shaped proliferating sporangia, smooth-walled oogonia which are crowded with different antheridial branches making a complicated knot around the former, and aplerotic oospores. Morphological and reproductive aspects of Pythium nodosum as well as the PCR of the internal transcribed spacer (ITS1) of the ribosomal nuclear DNA coupled with restriction fragment length polymorphism analysis are described here. The nucleotide sequences of ITS1 encoding 5.8S rRNA is also given.

Pythium ornacarpum: a new species with ornamented oogonia isolated from soil in France

1999

Pythium ornacarpum sp. nov. was isolated from a soil sample taken from Genlis in the Burgundy region of France. This species is unique because of its ornamented oogonia which are completely surrounded by antheridial filaments. The fungus is closely related to Pythium echinulatum Matthews. Morphological and reproductive aspects of this species as well as a study by PCR of the sequence of the internal transcribed spacer (ITS1) of the nuclear ribosomal gene and its comparison with related species are described here. The nucleotide sequence of the ITS1 region flaking the 5.8S rRNA of this species and other related species are also given here.