76 research outputs found

    Feasibility of recovered toner powder as an integral pigment in concrete

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    Colour is an important property in many construction materials with pigments, coatings and paints being used primarily for aesthetic, safety and restoration purposes. However, the use of integral pigments in materials like mortar and concrete can significantly increase material costs. Recovered toner powder (RTP) from printer and photocopier cartridges has the potential to be a low cost, sustainable alternative pigment. The aim of this research was to examine the feasibility of using cyan, yellow, magenta and black RTP to create a range of colour options for mortar and concrete, and thereafter assess the colour stability in outdoor, indoor, UV and wet/dry conditions using the colour change parameter (ΔE). The work showed that the RTP as a pigment could be blended to make a range of primary and secondary colours had good colour stability in all environments with minimal impact on selected properties of hardened concrete

    Does vegetation affect the methane oxidation efficiency of passive biosystems?

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    Abstract: It is often reported in the technical literature that the presence of vegetation improves the methane oxidation efficiency of biosystems; however, the phenomena involved and biosystem performance results are still poorly documented, particularly in the field. This triggered a study to assess the importance of vegetation in methane oxidation efficiency (MOE). In this study, 4 large scale columns, each filled with sand, topsoil and a mixture of compost and topsoil were tested under controlled conditions in the laboratory and partially controlled conditions in the field. Four series of laboratory tests and two series of field tests were performed. 4 different plant covers were tested for each series: Trifolium repens L. (White clover), Phleum pratense L. (Timothy grass), a mixture of both, and bare soil as the control biosystem. The study results indicated that up to a loading equal to 100 g CH4/m2/d, the type of plant cover did not influence the oxidation rates, and the MOE was quite high (⩾95%) in all columns. Beyond this point, the oxidation rate continued to increase, reaching 253 and 179 g CH4/m2/d in laboratory and field tests respectively. In the end, the bare soil achieved as high or higher MOEs than vegetated biosystems. Despite the fact that the findings of this study cannot be generalized to other types of biosystems and plants and that the vegetation types tested were not fully grown, it was shown that for the short-term tests performed and the types of substrates and plants used herein, vegetation does not seem to be a key factor for enhancing biosystem performance. This key conclusion does not corroborate the conclusion of the relatively few studies published in the technical literature assessing the importance of vegetation in MOE

    Plant Diversity Surpasses Plant Functional Groups and Plant Productivity as Driver of Soil Biota in the Long Term

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    One of the most significant consequences of contemporary global change is the rapid decline of biodiversity in many ecosystems. Knowledge of the consequences of biodiversity loss in terrestrial ecosystems is largely restricted to single ecosystem functions. Impacts of key plant functional groups on soil biota are considered to be more important than those of plant diversity; however, current knowledge mainly relies on short-term experiments.We studied changes in the impacts of plant diversity and presence of key functional groups on soil biota by investigating the performance of soil microorganisms and soil fauna two, four and six years after the establishment of model grasslands. The results indicate that temporal changes of plant community effects depend on the trophic affiliation of soil animals: plant diversity effects on decomposers only occurred after six years, changed little in herbivores, but occurred in predators after two years. The results suggest that plant diversity, in terms of species and functional group richness, is the most important plant community property affecting soil biota, exceeding the relevance of plant above- and belowground productivity and the presence of key plant functional groups, i.e. grasses and legumes, with the relevance of the latter decreasing in time.Plant diversity effects on biota are not only due to the presence of key plant functional groups or plant productivity highlighting the importance of diverse and high-quality plant derived resources, and supporting the validity of the singular hypothesis for soil biota. Our results demonstrate that in the long term plant diversity essentially drives the performance of soil biota questioning the paradigm that belowground communities are not affected by plant diversity and reinforcing the importance of biodiversity for ecosystem functioning
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