Salvador González-Carcedo

Oribatid mite (Acari) community structure in steppic habitats of Burgos Province, central northern Spain

This work is a study of the communities of oribatid mites in steppic areas of Burgos Province, central northern Spain, in relation to different habitat types belonging to natural or disturbed ecosystems. The primary objective was to find the relationship between anthropogenic use of land and several diversity indices. Parameters such as abundance, species richness, real diversity (H′) and equitability (J′) of the mite communities were calculated in 20 soil plots, sampled in spring and autumn 2000, belonging to the predominant habitat types of this area: (1) cultivated lands, (2) abandoned crop lands, (3) grasslands/pastures, and (4) natural oak forests or a pine plantation. The most widespread species in the area as well as the most abundant taxa overall are documented, together with the faunistic checklist of oribatid mites identified in the study. The results show a general decline in the composition of the oribatid community, in terms of species diversity and abundance, from non‐disturbed soils to cultivated lands. The number of species (richness) was usually higher in forest soils than in disturbed ecosystems, in which the most degraded soils showed the lowest number of species. The community analysis shows the differences due to habitat type and ubiquitous bioindicator species.

Soil Enzymology in the Recycling of Organic Wastes and Environmental Restoration

The bibliography on soil enzymes is extensive as showed by books and many review chapters devoted to the subject. The assays of soil enzymes are generally simple, accurate, sensitive and relatively rapid and for this reasons they have been extensively used to determine the effects of contaminants, changes in management practices and effects of environmental factors and plant cover on soil metabolism. However, the present enzyme assays determine potential rather than real enzyme activities due to the optimal conditions of the assays and they do not discriminate the contribution of extracellular stabilised enzymes from that of intracellular enzyme activities. The determination of the latter is important to evaluate the answer of soil microorganisms to any effect on soil. Methods based on fumigation of soil with chloroform or with the physiological response of soil microorganisms to glucose addition to soil present drawbacks. Presently, enzyme activities are still used to evaluate the response of soil metabolism to any effect not only in arable soils but also in forest soils. However, not always the past bibliography and the limits of the present enzyme assays are considered. A few innovative studies have been carried out. Measurements of enzyme activities have been combined with those on microbial diversity evaluated by molecular techniques. Both synthesis and persistence of phosphomonoesterases have been quantified in studies based on the stimulation of microbial growth by adding easily degradable organic compounds to soil. Metcalfe et al. (Appl Environ Microbiol 68:5042–5050, 2002) covered all events from gene presence, through gene expression and up to the detection of target enzyme in soil. The addition of sludge to a pasture soil increased chitinase activity and the number of actinobacteria but selected actinobacterium-like chitinase sequences. P. Nannipieri (&) L. Landi L. Giagnoni G. Renella Dipartimento di Scienza delle Produzioni Vegetali, del Suolo e Ambiente Agroforestale, University of Firenze, P.le delle Cascine 28, 50144, Florence, Italy e-mail: paolo.nannipieri@unifi.it C. Trasar-Cepeda et al. (eds.), Soil Enzymology in the Recycling of Organic Wastes and Environmental Restoration, Environmental Science and Engineering, DOI: 10.1007/978-3-642-21162-1_1, Springer-Verlag Berlin Heidelberg 2012 1 Enzyme assays distinguishing the contribution of extracellular stabilised enzymes from that of intracellular enzyme activities are needed. Future research should increase the number of enzyme activities which can be determined in soil. For example, an accurate assay for determining nuclease activity in soil is not available. It is important to set up accurate methods for extracting intracellular and stabilised extracellular proteins, which are largely prevailing, so as to be able to carry out the proteomic approach in soil. The understanding of microbial synthesis of proteins (functional proteomic) as affected by different environmental conditions can increase our knowledge on the synthesis of enzymes in soil whereas the characterization of proteins protected against microbial degradation by their interactions with surface-reactive particles or their inclusion within humic component (structural proteomic) can give insights on the stabilization of organic N, including enzymes, in soil. The set up of suitable techniques is needed to visualise the location of stabilised enzymes in soil sections by both scanning electron microscopy and transmission electron microscopy. Acid phosphatase activity has been detected in small (7 9 20 nm) fragments of microbial membranes, roots, mycorrhizae, etc. of soil but not in naturally-electron dense soil components (minerals) and in soil components reacting with OsO4 (humus) and this does not permit to localize extracellular enzymes or proteins stabilized by clay minerals or humic materials (Ladd and Butler, Aust J Soil Res 4:41–54, 1966).

Heavy-metal extraction from sewage sludge using phosphorous-based salts: optimization process with Na2H2P2O7

ABSTRACT Land application is one of the important disposal alternatives for sewage sludge, but availability of potential toxic metals often restricts its uses. Three phosphorous-based salts (Na2H2P2O7, K4P2O7, KH2PO4) were studied as potential metal extractants. The conclusions of the research were that greater extractive efficiency is achieved through a 30-min process of vertical shaking with disodium diacid pyrophosphate – Na2H2P2O7 – at a concentration of 0.2 M at pH 2. Alternatively, the optimized process with oscillating shaking equipment would require 60 min. In both cases the average of set of extracted metals is around 50%. A second extraction process with potassium pyrophosphate – K4P2O7 at pH 6 achieved the reduction of further total amounts of metal, upper 65% with respect to the initial content. In this way the sludge could be used in land applications, with restrictions on each soil, according to the limit values specified in the future regulations.