Evaluation of high local groundwater inflow to a rock tunnel by characterization of geological features

High local groundwater flow into rock tunnels is a technical and environmental problem for underground constructions. Geological features such as fault zones, open fractures and dykes can be the source of very high local inflows. However, prediction of possible groundwater inflow from these features using analytical and numerical tools often failed due to given hydrogeological assumptions and simplification of these heterogeneous media. In fact, the characteristics of geological features are not often detected by normal exploratory methods and missed from geological models. In order to identify factors that affect inflows from the geological features, a detailed investigation has been carried out at a tunnel excavated to supply potable water to the city of Semnan in Iran. The tunnel passes through formations of Cambrian age with thin and thickly laminated limestone, sandstone, shale and siltstone, which thrust on tuff Formation of Tertiary age by a main thrust fault. It was found out that:

(1)

High local inflows (from 20 up to 750 l/s) come from five geological features and much of tunnel is dry or has less inflow.

(2)

Maximum inflow occurs in an open fracture with amount of 750 l/s.

(3)

Faults have different hydraulic effect; they may act as conduits, barriers or combined conduit-barrier systems.

(4)

Dykes are generally barriers along which a large volume of water can be stored.

(5)

Evaluation of high local groundwater inflow to rock tunnels based on characterization of geological features is more reliable compared to available analytical and empirical estimation.

     

Charcoal addition to soils in NE England: a carbon sink with environmental co-benefits?

Interest in the application of biochar (charcoal produced during the pyrolysis of biomass) to agricultural land is increasing across the world, recognised as a potential way to capture and store atmospheric carbon. Its interest is heightened by its potential co-benefits for soil quality and fertility. The majority of research has however been undertaken in tropical rather than temperate regions. This study assessed the potential for lump-wood charcoal addition (as a substitute for biochar) to soil types which are typically under arable and forest land-use in North East England. The study was undertaken over a 28 week period and found:

i)

No significant difference in net ecosystem respiration (NER) between soils containing charcoal and those without, other than in week 1 of the trial.

ii)

A significantly higher dissolved organic carbon (DOC) flux from soils containing large amounts of charcoal than from those untreated, when planted with ryegrass.

iii)

That when increased respiration or DOC loss did occur, neither was sufficiently large to alter the carbon sink benefits of charcoal application.

iv)

That charcoal incorporation resulted in a significantly lower nitrate flux in soil leachate from mineral soils.

v)

That charcoal incorporation caused significant increases in soil pH, from 6.98 to 7.22 on bare arable soils when 87,500 kg charcoal/ha was applied.

Consideration of both the carbon sink and environmental benefits observed here suggests that charcoal application to temperate soils typical of North East England should be considered as a method of carbon sequestration. Before large scale land application is encouraged, further large scale trials should be undertaken to confirm the positive results of this research.     

Upgrading system-oriented ecotoxicological research

In the 1990s the Dutch government expressed the need to investigate the impacts of diffuse pollution at (sub)-ecosystem levels. The resulting Netherlands Stimulation Programme on System-oriented Ecotoxicological Research (SSEO programme) ran from 1998 to 2006. Its primary objective was to assess the impacts of low- to medium-level, diffuse, multiple contaminations on ecosystems. The research results were intended as underpinning for policies on environmental, conservation and nature issues. Research was carried out at three sites that were selected because of their importance for nature management and the presence of diffuse contamination. These sites were: a river meadow/floodplain area (Afferdensche en Deestsche Waarden), an estuarine reed-land area (Biesbosch) and an area of lowland peat soils that had been contaminated with urban waste in past centuries (De Ronde Venen).This introductory paper describes the set-up of the programme, the types of diffuse contamination, the interactions between pollutants and other stress factors, the various methodologies used to integrate the effects on (sub)ecosystem level, and the consequences for formulating policies for and the management of these types of locations.The results of the programme are diverse and complicated and show how difficult it is to draw firm, unambiguous, generic conclusions about the effects at the ‘total’ ecosystem level. It is however, possible to draw conclusions about effects on major components of ecosystems:

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The distribution of contaminants, both from a spatial, chemical and ecotoxicological point of view, plays a decisive role in actual effect levels. Even when total contaminant loads are high, such as in estuarine and floodplain areas, bioavailability may be so low that the actual effects are limited. The irregular, heterogeneous, spatial distribution of contaminants in the soil further complicates effect studies, impact assessments and monitoring.

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Various stress factors, other than contaminants, both natural and anthropogenic, also play a role. The negative effect of the repeated inundation of floodplain areas, for instance, greatly interferes with the impact of contaminants in the lower soil layers.

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A major problem is to find a method to extrapolate the observations from individual and population levels to the ecosystem level. In addition to traditional food-chain models and similar approaches, the potential of other, not yet extensively explored, ecosystem interaction mechanisms is discussed.

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Finally, the results have to be interpreted from a policy point of view, both for national soil policies and for implementing the EU Soil Strategy regulations.

     

Nanomaterials for environmental studies: Classification, reference material issues, and strategies for physico-chemical characterisation

NanoImpactNet is a European Commission Framework Programme 7 (FP7) funded project that provides a forum for the discussion of current opinions on nanomaterials in relation to human and environmental issues. In September 2008, in Zurich, a NanoImpactNet environmental workshop focused on three key questions:

1.

What properties should be characterised for nanomaterials used in environmental and ecotoxicology studies?

2.

What reference materials should be developed for use in environmental and ecotoxicological studies?

3.

Is it possible to group different nanomaterials into categories for consideration in environmental studies?

Such questions have been, at least partially, addressed by other projects/workshops especially in relation to human health effects. Such projects provide a useful basis on which this workshop was based, but in this particular case these questions were reformulated in order to focus specifically on environmental studies. The workshop participants, through a series of discussion and reflection sessions, generated the conclusions listed below.The physicochemical characterisation information identified as important for environmental studies included measures of aggregation/agglomeration/dispersability, size, dissolution (solubility), surface area, surface charge, surface chemistry/composition, with the assumption that chemical composition would already be known.There is a need to have test materials for ecotoxicology, and several substances are potentially useful, including TiO₂ nanoparticles, polystyrene beads labelled with fluorescent dyes, and silver nanoparticles. Some of these test materials could then be developed into certified reference materials over time.No clear consensus was reached regarding the classification of nanomaterials into categories to aid environmental studies, except that a chemistry-based classification system was a reasonable starting point, with some modifications. It was suggested, that additional work may be required to derive criteria that can be used to generate such categories, that would also include aspects of the material structure and physical behaviour.     

Microclimatic coupling as a solution to improve building energy simulation in an urban context

To streamline the design of the energy efficient buildings, appropriate tools are needed to assess their energy performance taking into account the microclimatic context.Numerical simulation seems to be the most suitable issue, but none tool is dedicate to the direct evaluation of the microclimate influence on the building energy consumption. A complete solution could be to use both CFD and thermoradiative simulation tools complementary with the coupling technique perspective. This paper presents both a developed CFD-thermoradiative coupled simulation tool and a typical application on an urban fragment.The results lead to two kind of observations:

•

Integration of the thermal model of a building in the microclimatic simulation platform enable a quantitative evaluation of the building energy demand regarding different urban design scenarii (e.g. mineralized vs vegetated).

•

Different physical phenomena do not contribute as much in the energy balance and it is important to compute precisely each one to obtain the small scale microclimatic influence.