Mobilization of natural nitrate (NO3-) deposits in the subsoil by irrigation water in arid and semiarid regions has the potential to produce large groundwater NO3-concentrations. The use of isotopes to distinguish between natural and anthropogenic NO3- sources in these settings could be complicated by the wide range in delta15N values of natural NO3-. An approximately 10 000 year record of pale...

This paper documents the successful application of explosive compaction technology for the densification of granular soils using case history data from a number of sites. The data include densification projects in urban areas, for dam foundations and for offshore structures. The paper provides general background information on the theory of explosive compaction of soils, design considerations, ...

Plant carbon (C) and nitrogen (N) stoichiometry play an important role in the maintenance of ecosystem structure and function. To decipher the influence of changing environment on plant C and N stoichiometry at the subcontinental scale, we studied the shoot and root C and N stoichiometry in two widely distributed and dominant genera along a 2,200-km climatic gradient in China's grasslands. Rela...

This study evaluated the effects of young poplar plantations on understory plant diversity in the Dongting Lake wetlands, China. Poplar plantations resulted in a higher species number and Shannon's diversity. Species compositions were different between areas with poplar and reed populations: a lower ratio of hygrophytes but a higher ratio of mesophytes, and a higher ratio of heliophytes but a l...

The average ionic strength of 20 West Australian soils was found to be 0·0048. The effects of three electrolytes (deionized water, CaCl2 and KN03), three ionic strengths (0'03. 0·005 and soil ionic strength at field capacity, Is) and two soil liquid ratios (1:5 and 1:10) on the pH of 15 soils were investigated. pH measurements in solutions of ionic strength 0·005 differed the least from measure...

Although most models suggest continental Antarctica was covered by ice during the Last Glacial Maximum (LGM) it has been speculated that endemic species of soil invertebrates could have survived the Pleistocene at high elevation habitats protruding above the ice sheets. We analyzed a series of soil samples from different elevations at three locations along the Beardmore Glacier in the Transanta...

Concentrations and isotopic compositions of lead in the total and mobile (acid-soluble and carbonatebound) forms were determined in remote and roadside Chestnut soils in the dry steppe region of Low Volga, Russia. As a reference to evaluate the level of modern soil contamination with lead, we used ancient soil buried under a Bronze Age kurgan about 4500 years ago. In comparison with buried soil...

Grasslands have a long history of invasion by exotic annuals, which may alter microbial communities and nutrient cycling through changes in litter quality and biomass turnover rates. We compared plant community composition, soil chemical and microbial community composition, potential soil respiration and nitrogen (N) turnover rates between invaded and restored plots in inland and coastal grassl...

While it is well established that plants associating with arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi cycle carbon (C) and nutrients in distinct ways, we have a limited understanding of whether varying abundance of ECM and AM plants in a stand can provide integrative proxies for key biogeochemical processes. We explored linkages between the relative abundance of AM and ECM trees...

It is widely accepted that nitrogen limits primary production in temperate forests, although co-limitation by N and P has also been suggested, and on some soils Ca and base cations are in short supply. I conducted a meta-analysis to assess the strength of existing experimental evidence for limitation of primary production by N, P, and Ca in hardwood forests of the northeastern United States and...