Effect of Water Table Level on Metal Mobility at Different Depths in Wetland Soils of the Scheldt Estuary (Belgium)

Water, Air, & Soil Pollution - Many management strategies to improve the health of Chesapeake Bay focus on reducing losses of sediments and nutrients from agricultural land. Plot-scale studies...     

The impact of climate change on the yield and quality of Saaz hops in the Czech Republic

The impact of climate change on the production and quality of hops Humulus lupulus will depend on future weather conditions in the growing season. Our simulations suggest that hops will be particularly vulnerable to a change in climate. Even with the modest warming so far experienced yields have stagnated and quality declined. Recorded observations show an increase in air temperature which is associated with an earlier onset of hop phenological phases and a shortening of the vegetation period. Simulations using future climate predict a decline in both yields, of up to 7–10%, and α-acid content, of up to 13–32%, the latter a major determinant of quality. The concentration of hop cultivation in a comparatively small region in the Czech Republic makes it more vulnerable than if the crop were grown in more areas with different climates. Thus climate change may gradually lead to changes in the regionalization of hop production. Policy assistance may be necessary for the adaptation of the Czech hop growing industry to changed climatic conditions.     

Electrical measurement of tree root absorbing surfaces by the earth impedance method: 2. Verification based on allometric relationships and root severing experiments

We validated, by means of allometric relationships and root severing experiments, the modified earth impedance method developed for measuring absorbing root surfaces. For the allometric studies, a series of 350 small and large trees of six broadleaf and coniferous species in several experimental sites was examined. We found a good linear ln-ln fit between absorbing root surface area and basal area (or stem cross-sectional area at the root collar in seedlings) over a range of stem diameters from 0.5-55 cm. The absorbing root surface area also changed consistently with crown projected area and the root-accessed area (territory) of the tree. At the whole-tree level, absorbing root surface area reached about 70 times that of basal area and 40% of crown projected area, or roughly 1/3 of the root-accessed area in Norway spruce (in this species, the ratio was relatively larger in small trees and smaller in large trees). The absorbing root surfaces of mechanically severed parts of Norway spruce root systems changed in about the same proportions as the geometrically determined parts of the severed root systems. These results are promising and support field applications of the method in biological and ecological studies.     

Rates of forest floor decomposition and soil forming processes as indicators of forest ecosystem functioning on a polluted dredged sediment landfill

Results of intensive monitoring of forest floor decomposition rates and soil forming processes after afforestation of a calcareous upland dredged sediment landfill with an oxidised surface soil are presented. Nutrient status of the sediment substrate favours tree growth and allows for afforestation and thus an integration in the landscape. Soil processes on the landfill resulted in small differences between the surface and the subsurface soil layer, although higher soil organic carbon and Cd concentrations in the surface soil were observed. So far, tree species had a minor impact on soil processes. Relative to the uncontaminated covered part of the site and to general references, forest floor decomposition was found to be relatively fast for sycamore maple and pedunculate oak. Despite the pollution status of the dredged sediment landfill, the sediment substrate was favourable for forest floor decomposition. This might indicate that the soil nutrition status and the high carbonate status override the negative impact of soil pollution with metals and other pollutants. Application of a covering layer composed of uncontaminated soil material resulted in lower Cd concentrations in earthworms, but concentrations were still higher than for references. We conclude from the observations that polluted but fertile soils allow for afforestation and for regular forest floor decomposition with normal or slightly elevated metal concentrations. Only long-term observations of such new forests will lead to a correct site-specific assessment of the actual ecological risks, but after 16 years of landfilling and 12 years of afforestation no adverse effects were observed.     

Susceptibility of humic acids from soils with various contents of metals to microbial utilization and transformation

Humic acids (HAs) from a pseudogley soil with various metal contents were added as supplemental sources of nutrients, or as the sole sources of carbon or nitrogen, to aerobic cultures of complex microbial populations indigenous to the same individual soils. Depending on nutrient conditions in the individual cultures and origin of HAs, between 44% and 67% of the added HAs were utilized. The lowest utilization rate was obtained for HAs from soil heavily contaminated with Mg. The overall carbon mineralization in the microbial cultures was significantly reduced in the presence of HAs. Simultaneously, the formation of microbial biomass was enhanced up to 261%. Variovorax (Alcaligenes) paradoxus, Pseudomonas fluorescens, and a yeast Cryptococcus sp. have been identified as the dominant microbial species utilizing HAs. The individual HA preparations re-isolated from the microbial cultures exhibited distinct changes in elemental and structural characteristics. Diminished contents of ash and alterations in infra-red absorptions indicated a splitting of organic and mineral components in HAs exposed to microbial activities.     

Use of psychrophilic xylanases provides insight into the xylanase functionality in bread making

The bread-improving potential of three psychrophilic xylanases from Pseudoalteromonas haloplanktis TAH3A (XPH), Flavobacterium sp. MSY-2 (rXFH), and unknown bacterial origin (rXyn8) was compared to that of the mesophilic xylanases from Bacillus subtilis (XBS) and Aspergillus aculeatus (XAA). XPH, rXFH, and rXyn8 increased specific bread volumes up to 28%, 18%, and 18%, respectively, while XBS and XAA gave increases of 23% and 12%, respectively. This could be related to their substrate hydrolysis behavior. Xylanases with a high capacity to solubilize water-unextractable arabinoxylan (WU-AX) during mixing, such as XBS and XPH, increased bread volume more than xylanases that mainly solubilized WU-AX during fermentation, such as rXFH, rXyn8, and XAA. Irrespective of their intrinsic bread-improving potential, the dosages needed to increase bread volume to a similar extent were much lower for psychrophilic than for mesophilic xylanases. The xylanase efficiency mainly depended on the enzyme's temperature activity profile and its inhibition sensitivity.     

Colonization factors of Campylobacter jejuni in the chicken gut

ABSTRACT: Campylobacter contaminated broiler chicken meat is an important source of foodborne gastroenteritis and poses a serious health burden in industrialized countries. Broiler chickens are commonly regarded as a natural host for this zoonotic pathogen and infected birds carry a very high C. jejuni load in their gastrointestinal tract, especially the ceca. This eventually results in contaminated carcasses during processing. Current intervention methods fail to reduce the colonization of broiler chicks by C. jejuni due to an incomplete understanding on the interaction between C. jejuni and its avian host. Clearly, C. jejuni developed several survival and colonization mechanisms which are responsible for its highly adapted nature to the chicken host. But how these mechanisms interact with one another, leading to persistent, high-level cecal colonization remains largely obscure. A plethora of mutagenesis studies in the past few years resulted in the identification of several of the genes and proteins of C. jejuni involved in different aspects of the cellular response of this bacterium in the chicken gut. In this review, a thorough, up-to-date overview will be given of the survival mechanisms and colonization factors of C. jejuni identified to date. These factors may contribute to our understanding on how C. jejuni survival and colonization in chicks is mediated, as well as provide potential targets for effective subunit vaccine development.     

Solid fraction of separated digestate as soil improver: implications for soil fertility and carbon sequestration

Journal of Soils and Sediments - This study investigated the C and N mineralisation potential of solid fractions (SFs) from co-digestated pig manure after P-stripping (P-POOR SF) in comparison with...     

Cruciferous plants' use as biofumigants in potato against wireworms

In Slovenia, only tefluthrin is registered for controlling wireworms. In order to investigate the potential alternatives for controlling wireworms in potato, the field experiment was conducted in the period from 2011 (year 1) to 2012 (year 2). As alternatives, different Brassica crops (year 1: rapeseed, oilseed radish and white mustard; year 2: rapeseed, oilseed radish, oilseed rape, kale and white mustard) were tested (fresh foliage was incorporated into the soil by ploughing) for their biofumigant effect. Results of our investigation showed that in both years the potato yield was affected by measures of pest control; however, none of the tested biofumigant plants proved to be a potentially promising candidate in wireworm control. The rapid release of volatiles after plant chopping before and during incorporation into the soil could be the reason of inefficacy in our experiment. In our study, most wireworm damage occurred on biggest potato tubers. Moreover, edge effect of the field played an important role in our experiment in year 1. Treatment (chemical or biological) of wireworms only at the edge part of the field could offer a cost-effective, time-saving and environmentally more friendly way of controlling studied pest organism.     

Induction of seroconversion and persistence of Salmonella Typhimurium in pigs are strain dependent

Foodborne salmonellosis is one of the most important bacterial zoonotic diseases worldwide. Salmonella Typhimurium is the serovar most frequently isolated from persistently infected slaughter pigs in Europe. Salmonella Typhimurium pathogenesis is host species specific. In addition, differences in in vitro behaviour of Salmonella Typhimurium strains have also been described, which may be reflected by a different course of infection within a host species. We compared the course of a Salmonella Typhimurium infection in pigs, using two Salmonella Typhimurium strains that were able to interfere with MHC II expression on porcine macrophages to a different extent in vitro. After experimental inoculation, blood and faecal samples from all pigs were collected at regular time points. At 40 days post inoculation (pi), animals were euthanized and tissue samples were bacteriologically analysed. The proportion of serologically positive piglets at 33 days pi was significantly higher in pigs that were inoculated with the strain that did not downregulate MHC II expression in vitro. Furthermore, this strain was less frequently shed and isolated in lower numbers from tonsils and ileocaecal lymph nodes than the strain that was able to markedly downregulate MHC II expression in vitro. We thus found that the delayed onset of seroconversion after oral inoculation of piglets with a particular Salmonella Typhimurium strain coincided with higher faecal shedding and increased persistence. Strain specific differences in Salmonella pathogenesis might thus have repercussions on the serological detection of Salmonella Typhimurium infections in pigs.