Cow excrements enhance the occurrence of tetracycline resistance genes in soil regardless of their oxytetracycline content

Fertilizing soils with animal excrements from farms with common antibiotic use represents a risk of disseminating antibiotic resistance genes into the environment. In the case of tetracycline antibiotics, it is not clear, however, whether the presence of antibiotic residues further enhances the gene occurrence in manured soils. We established a microcosm experiment in which 3 farm soils that had no recent history of fertilization with animal excrements were amended on a weekly basis (9 times) with excrements from either an oxytetracycline-treated or an untreated cow. Throughout the study, the concentration of oxytetracycline in excrements from the treated cow was above 500 μg g⁻¹ dw, whereas no oxytetracycline was detected in excrements from the healthy cow. Both excrements contained tetracycline resistance (TC-r) genes tet(L), tet(M), tet(V), tet(Z), tet(Q) and tet(W). The excrements from the treated cow also contained the tet(B) gene, and a higher abundance of tet(Z), tet(Q) and tet(W). Three weeks after the last excrement addition, the individual TC-r genes differed in their persistence in soil: tet(Q) and tet(B) were not detectable while tet(L), tet(M), tet(Z) and tet(W) were found in all 3 soils. There were, however, no significant differences in the total number, nor in the abundance, of TC-r genes between soil samples amended with each excrement type. The oxytetracycline-rich and the oxytetracycline-free excrement therefore contributed equally to the increase of tetracycline resistome in soil. Our results indicate that other mechanisms than OTC-selection pressure may be involved in the maintenance of TC-r genes in manured soils.     

Objective exposure to road traffic noise,noise annoyance and self-rated poor health – framing the relationship between noise and health as a matter of multiple stressors and resources in urban neighbourhoods

Borrowing from concepts of socio-environmental epidemiology and psychology, we conceived self-rated health as a function of multiple physical and psychosocial stressors and resources at the residential neighbourhood and individual level. In this model of multiple stressors, objective exposure to road traffic noise was specified as a physical stressor whose effect on health may be mediated and modified by residents’ subjective response to noise (serious noise annoyance). Self-reported hearing disability, recreational coping in green areas and residential neighbourhood satisfaction were examined as additional psychosocial stressors or resources, independently of socio-demographic and -economic factors. Results from our empirical analysis based on two studies and multivariable logistic regressions might support the idea that environmental planning should overcome sectoral boundaries and adopt an integrative approach including objective exposures, residents’ subjective responses, and perceived resources.     

Integrated Freshwater Solutions — A New Zealand Application of Mediated Modeling

Mediated Modeling (MM) refers to “model building with stakeholders,” enabling collaborative learning and decision support. This article presents results from the Integrated Freshwater Solutions (IFS — www.ifs.org.nz ) action research project in the Manawatū River watershed, New Zealand. Water quality in the watershed often rates poorly, with the key issues being sedimentation, eutrophication, and habitat destruction. IFS is to develop and test MM to support collaborative and adaptive freshwater management. The project team was presented with the opportunity to collaborate with the Manawatū River Leaders' Forum (MRLF), an initiative driven by the Regional Council to improve water quality. This article describes the process of MM and how it was adapted to meet the needs of MRLF stakeholders. This highlights some important conditions for collaborative and adaptive capacity building. The MM/MRLF stakeholders, represented: industry, farming, local and regional authorities, environmental groups, and indigenous Māori iwi/hapū (tribe/sub‐tribe). This article describes how MM assisted early in the collaborative process to develop the following: (1) a shared and more integrated understanding of causes and effects and (2) a sense of the order of magnitude of the problems and the impact proposed solutions might have. It also describes how the context of politics, time, and resource constraints played an important role reverting to a more traditional planning approach part way through the process.     

Transport and Immobilization of 2,4,6 15N-Trinitrotoluene in Soil Microcosms Subjected to Long Term Incubation Under Aerobic Conditions

¹⁵N-labeling and solid-state ¹³C and ¹⁵N nuclear magnetic resonance (NMR) spectroscopy was applied to study the immobilization of 2,4,6 trinitrotoluene (TNT) into soil organic matter (SOM). Uncontaminated soil from the Ap horizon of a Luvisol was mixed with ¹⁵N-TNT (enrichment: 99 atm%) and laid over an unspiked layer of the same material. The latter covered soil from the Bt horizon. The microcosms were aerobically incubated under laboratory conditions for up to 11 months. After 1 week, within the total microcosm approximately 90% of the added ¹⁵N (¹⁵N_add) were recovered, mostly in the top layer (87%). After 11 months, this amount decreased to 71%, indicating losses due to denitration or transamination. Within two months, half of ¹⁵N_add had been immobilized in the residues not extractable with organic solvents and water. The amount of the sequestered ¹⁵N_add remained fairly constant until the end of the experiment pointing towards a high stability of TNT-SOM associates. Solid-state ¹⁵N NMR revealed their formation by covalent binding, most tentatively as amides. Complete reduction of TNT to triaminotoluene (TAT) was not prerequisite. The most pronounced downwards movement of ¹⁵N-TNT occurred during the first two months. The major part of it, however, experienced quick immobilization, leaving approximately 10% of ¹⁵N_add recovered in the leachate at the end of the experiment. Calculations indicated contributions of inorganic ¹⁵N_add. Approximately 25% of its organic ¹⁵N_add originated from condensed N, suggesting that in soils the transport of partly reduced TNT is in close association with the organic matter of the soil solution to which they are covalently bound.     

Additive und synergistische Kombinationswirkungen von Xenobiotika in subtoxischen Konzentrationen auf menschliche Fibroblasten

The toxic combination effects of xenobiotics of different substance classes were investigated in human fibroblasts. Subtoxic concentrations of 4-chloroaniline enhanced the toxicity of 2,4-dichlorophenoxyacetic acid (2,4-D, dimethylammonium salt) in an additive manner. A mixture of 4-chloroaniline, dicofol and 4-chlorophenol increased the toxicity of 2,4-D synergistically. The concentrations of the components used in the mixture were one third of their ?no observed effect concentrations” (NOEC). The combination of 4-chloroaniline, dicofol and 4-chlorophenol (without 2,4-D) at subtoxic concentrations also showed synergistic effects. The great differences in the lipophilicity of the combined substances might be the cause of the synergistic action.     

Modeling carbon sequestration under zero-tillage at the regional scale. II. The influence of crop rotation and soil type

For policy decisions with respect to CO₂-mitigation measures in the agricultural sector, national and regional estimations of the efficiency of such measures are required. The conversion of ploughed cropland to zero-tillage is discussed as an option to reduce CO₂ emissions and promises at the same time effective soil and water conservation. Based on the upscaling of simulation results with the soil and land resources information system SLISYS-BW, estimations of CO₂-mitigation rates in relation to crop rotations and soil type have been made for the state of Baden-Württemberg (Germany). The results indicate considerable differences in the CO₂-mitigation rates between crop rotations ranging from 0.48 to 0.03 Mg C ha⁻¹ a⁻¹ for winter cereals–spring cereals–rape rotations and winter cereals–spring cereals–corn silage rotations, respectively. The efficiency of the crop rotations is strongly related to the total carbon input and in particular the amount of crop residues. Among the considered soil types, highest CO₂-mitigation rates are associated with Cumulic Anthrosols (0.62 Mg C ha⁻¹ a⁻¹) and the lowest with Gleysols (−0.01 Mg C ha⁻¹ a⁻¹). An agricultural extensification scenario with conventional plowing but conversion of the presently applied intensive crop rotations to a clover–clover–winter cereals rotation indicated a CO₂-mitigation potential of 466 Gg C a⁻¹. However, the present high market prices for cereals and increasing demand for energy production from biomass encourages an intensification of the agricultural production and an excessive removal of biomass which in future will seriously reduce the potential for carbon sequestration on cropland.     

The effect of fire on soil organic matter--a review

The extent of the soil organic carbon pool doubles that present in the atmosphere and is about two to three times greater than that accumulated in living organisms in all Earth's terrestrial ecosystems. In such a scenario, one of the several ecological and environmental impacts of fires is that biomass burning is a significant source of greenhouse gases responsible for global warming. Nevertheless, the oxidation of biomass is usually incomplete and a range of pyrolysis compounds and particulate organic matter (OM) in aerosols are produced simultaneously to the thermal modification of pre-existing C forms in soil. These changes lead to the evolution of the OM to "pyromorphic humus", composed by rearranged macromolecular substances of weak colloidal properties and an enhanced resistance against chemical and biological degradation. Hence the occurrence of fires in both undisturbed and agricultural ecosystems may produce long-lasting effects on soils' OM composition and dynamics. Due to the large extent of the C pool in soils, small deviations in the different C forms may also have a significant effect in the global C balance and consequently on climate change. This paper reviews the effect of forest fires on the quantity and quality of soils' OM. It is focused mainly on the most stable pool of soil C; i.e., that having a large residence time, composed of free lipids, colloidal fractions, including humic acids (HA) and fulvic acids (FA), and other resilient forms. The main transformations exerted by fire on soil humus include the accumulation of new particulate C forms highly resistant to oxidation and biological degradation including the so-called "black carbon" (BC). Controversial environmental implications of such processes, specifically in the stabilisation of C in soil and their bearing on the global C cycle are discussed.     

Comparison of selected aerobic and anaerobic procedures for MSW treatment

This paper considers selected efficiency rates and process data of aerobic and anaerobic procedures for the treatment of municipal solid waste and residual waste. Data are exclusively related to mechanical-biological treatment (MBT) procedures for generating waste appropriate for landfilling. The following aspects are regarded: general framework conditions for the application of MBT, efficiency of decomposition and of stabilisation, air and water emissions and energy balances. The presented data can be used for more efficient planning. In comparison to aerobic processes, anaerobic digestion can be ecologically advantageous, particularly with regard to exhaust emissions and energy balances. On the other hand, the wastewater emissions and the wastewater treatment required must be regarded as disadvantageous. Due to the relatively short period of operational history of most anaerobic processes for mechanical-biological waste treatment and thus limited experiences, operational reliability of anaerobic processes is slightly lower. Extensive biological stability of the treated waste for low-emission disposal cannot be reached by anaerobic digestion alone, but only in combination with additional aerobic post-treatment. In connection with the utilisation of renewable energies and the rising relevancy of climate protection, it can be affirmed that anaerobic digestion for the treatment of municipal solid waste has a high potential for further development.     

Emotion as mediators of the relations between perceived supervisor support and psychological hardiness on employee cynicism

In this study we explore whether emotion experienced at work mediates the relationships between perceived supervisor support, psychological hardiness, and employee cynicism. Data were collected from employees working at a medical technology company located in Switzerland. Mediational analyses showed that employees' positive and negative emotions experienced amidst an organizational crisis fully accounted for the relations between perceived supervisor support and cynicism and psychological hardiness and cynicism. Practical implications and directions for future research are discussed. Copyright © 2006 John Wiley & Sons, Ltd.